Patent Publication Number: US-7912004-B2

Title: Generic access to the Iu interface

Description:
CLAIM OF BENEFIT TO PRIOR APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application 60/807,470, entitled “E-UMA Technology,” filed Jul. 14, 2006; U.S. Provisional Application 60/823,092, entitled “Generic Access to the Iu Interface,” filed Aug. 21, 2006; U.S. Provisional Application 60/862,564, entitled “E-UMA—Generic Access to the Iu Interface,” filed Oct. 23, 2006; and U.S. Provisional Application 60/949,826, entitled “Generic Access to the Iu Interface,” filed Jul. 13, 2007. The contents of each of these four provisional applications are hereby incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The field of invention relates generally to telecommunications. More particularly, this invention relates to a mechanism for extending Unlicensed Mobile Access (UMA) or Generic Access Network (GAN) to inter-work with a GSM core network using the Universal Mobile Telecommunication System (UMTS) Iu interface. 
     BACKGROUND OF THE INVENTION 
     Licensed wireless systems provide mobile wireless communications to individuals using wireless transceivers. Licensed wireless systems refer to public cellular telephone systems and/or Personal Communication Services (PCS) telephone systems. Wireless transceivers include cellular telephones, PCS telephones, wireless-enabled personal digital assistants, wireless modems, and the like. 
     Licensed wireless systems utilize wireless signal frequencies that are licensed from governments. Large fees are paid for access to these frequencies. Expensive base station (BS) equipment is used to support communications on licensed frequencies. Base stations are typically installed approximately a mile apart from one another (e.g., cellular towers in a cellular network). The wireless transport mechanisms and frequencies employed by typical licensed wireless systems limit both data transfer rates and range. As a result, the quality of service (voice quality and speed of data transfer) in licensed wireless systems is considerably inferior to the quality of service afforded by landline (wired) connections. Thus, the user of a licensed wireless system pays relatively high fees for relatively low quality service. 
     Landline (wired) connections are extensively deployed and generally perform at a lower cost with higher quality voice and higher speed data services. The problem with landline connections is that they constrain the mobility of a user. Traditionally, a physical connection to the landline was required. 
     In the past few years, the use of unlicensed wireless communication systems to facilitate mobile access to landline-based networks has seen rapid growth. For example, such unlicensed wireless systems may support wireless communication based on the IEEE 802.11a, b or g standards (WiFi), or the Bluetooth® standard. The mobility range associated with such systems is typically on the order of 100 meters or less. A typical unlicensed wireless communication system includes a base station comprising a wireless access point (AP) with a physical connection (e.g., coaxial, twisted pair, or optical cable) to a landline-based network. The AP has a RF transceiver to facilitate communication with a wireless handset that is operative within a modest distance of the AP, wherein the data transport rates supported by the WiFi and Bluetooth® standards are much higher than those supported by the aforementioned licensed wireless systems. Thus, this option provides higher quality services at a lower cost, but the services only extend a modest distance from the base station. 
     Currently, technology is being developed to integrate the use of licensed and unlicensed wireless systems in a seamless fashion, thus enabling a user to access, via a single handset, an unlicensed wireless system when within the range of such a system, while accessing a licensed wireless system when out of range of the unlicensed wireless system. 
     SUMMARY OF THE INVENTION 
     Some embodiments provide a method of registering a user equipment (UE) in a communication system that includes a licensed wireless communication system and a generic access network (GAN) that has a generic access network controller (GANC). The method sends a register request message from the UE to the GANC that indicates a GAN mode capability of A/Gb only for the UE. When the GANC has a GAN mode capability of A/Gb, the GANC registers the UE with the GAN. When the GANC has a GAN mode capability of Iu only, the GANC rejects the register request message. When the GANC has a GAN mode capability of both A/Gb and Iu, the GANC registers the UE based on a set of GANC mode selection rules that the GANC applies for registering UEs with the GAN. 
     Some embodiments provide a method of activating a packet transport channel (PTC) in a communication system that includes a first licensed wireless communication system and a second generic access network (GAN) that has a generic access network controller (GANC). The GANC is communicatively coupled to the first communication system through a universal mobile telecommunication system (UMTS) terrestrial radio access network (UTRAN) Iu interface. The method sends a GA-PSR activate PTC request message from the GANC to a user equipment (UE). The message comprises a terminal endpoint identifier (TEID) that the GANC assigns to the UE. 
     Some embodiments provide a communication system that includes a first licensed wireless communication system, a second generic access network (GAN) that includes a generic access network controller (GANC). The GANC is communicatively coupled to the first communication system through a universal mobile telecommunication system (UMTS) terrestrial radio access network (UTRAN) Iu interface. The communication system also includes a user equipment (UE). The GANC includes a UDP protocol layer and a GTP-U protocol layer over the UDP protocol layer of the GANC. The UE includes a UDP protocol layer and a GTP-U protocol layer over said UDP protocol layer of the UE. The UDP protocol layer of the GANC is communicatively coupled to the UDP protocol layer of the UE. The GTP-U protocol layer of the GANC is communicatively coupled to the GTP-U protocol layer of the UE. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The novel features of the invention are set forth in the appended claims. However, for purpose of explanation, several embodiments of the invention are set forth in the following figures. 
         FIG. 1  illustrates an integrated communication system (ICS) of some embodiments. 
         FIG. 2  illustrates several applications of an ICS in some embodiments. 
         FIG. 3  illustrates the overall A/Gb-mode GAN functional architecture of some embodiments. 
         FIG. 4  illustrates the overall Iu-mode GAN functional architecture of some embodiments. 
         FIG. 5  illustrates the basic elements of a Femtocell system architecture with Asynchronous Transfer Mode based Iu interfaces towards the core network in some embodiments. 
         FIG. 6  illustrates the basic elements of a Femtocell system architecture with an IP based Iu interface towards the core network in some embodiments. 
         FIG. 7  illustrates the CS domain control plane architecture of some embodiments. 
         FIG. 8  illustrates the CS domain control plane architecture of some embodiments. 
         FIG. 9  illustrates the CS domain control plane architecture of some embodiments. 
         FIG. 10  illustrates the UE CS domain control plane architecture of some embodiments. 
         FIG. 11  illustrates CS domain user plane protocol architecture of some embodiments. 
         FIG. 12  illustrates CS domain user plane protocol architecture of some embodiments. 
         FIG. 13  illustrates the UE CS domain user plane architecture of some embodiments. 
         FIG. 14  illustrates PS domain control plane architecture of some embodiments. 
         FIG. 15  illustrates PS domain control plane architecture of some embodiments. 
         FIG. 16  illustrates the UE PS domain control architecture of some embodiments. 
         FIG. 17  illustrates PS domain user plane protocol architecture of some embodiments. 
         FIG. 18  illustrates PS domain user plane protocol architecture of some embodiments. 
         FIG. 19  illustrates PS domain user plane protocol architecture of some embodiments. 
         FIG. 20  illustrates the UE PS domain user plane architecture of some embodiments. 
         FIG. 21  illustrates state diagram for generic access in the UE of some embodiments. 
         FIG. 22  illustrates GAN security mechanisms of some embodiments. 
         FIG. 23  illustrates discovery procedure of some embodiments. 
         FIG. 24  illustrates registration procedure of some embodiments. 
         FIG. 25  illustrates De-Registration initiated by the UE in some embodiments. 
         FIG. 26  illustrates De-Registration initiated by the GANC in some embodiments. 
         FIG. 27  illustrates registration Update Uplink of some embodiments. 
         FIG. 28  illustrates Registration Update Downlink of some embodiments. 
         FIG. 29  illustrates Keep Alive procedure of some embodiments. 
         FIG. 30  illustrates Cell Broadcast Information in some embodiments. 
         FIG. 31  illustrates GA-CSR Connection Establishment of some embodiments. 
         FIG. 32  illustrates GA-CSR Connection Release in some embodiments. 
         FIG. 33  illustrates Security Mode Control in some embodiments. 
         FIG. 34  illustrates core network to UE NAS signaling in some embodiments. 
         FIG. 35  illustrates UE to core network NAS signaling in some embodiments. 
         FIG. 36  illustrates Mobile Originated CS Call in some embodiments. 
         FIG. 37  illustrates Mobile Originated CS Call in some embodiments. 
         FIG. 38  illustrates Mobile Terminated CS Call in some embodiments. 
         FIG. 39  illustrates UE initiated CS Call clearing in some embodiments. 
         FIG. 40  illustrates CS Handover from GERAN to GAN in some embodiments. 
         FIG. 41  illustrates an alternative procedure performed during GERAN to GAN in some embodiments. 
         FIG. 42  illustrates CS Handover from UTRAN to GAN in some embodiments. 
         FIG. 43  illustrates an alternative procedure performed during UTRAN to GAN in these embodiments. 
         FIG. 44  illustrates CS Handover from GAN to GERAN in some embodiments. 
         FIG. 45  illustrates CS Handover from GAN to UTRAN in some embodiments. 
         FIG. 46  illustrates GA-PSR Connection Establishment of some embodiments. 
         FIG. 47  illustrates GA-PSR Connection Release in some embodiments. 
         FIG. 48  illustrates the message flow for PS security mode control in some embodiments. 
         FIG. 49  illustrates core network to user equipment PS NAS signaling in some embodiments. 
         FIG. 50  illustrates user equipment to core network NAS signaling in some embodiments. 
         FIG. 51  illustrates PTC initial activation in some embodiments. 
         FIG. 52  illustrates PTC Data Transfer in some embodiments. 
         FIG. 53  illustrates UE initiated PTC deactivation in some embodiments. 
         FIG. 54  illustrates UE initiated PTC re-activation in some embodiments. 
         FIG. 55  illustrates Network initiated PTC de-activation in some embodiments. 
         FIG. 56  illustrates Network initiated PTC re-activation in some embodiments. 
         FIG. 57  illustrates Implicit PTC deactivation in some embodiments. 
         FIG. 58  illustrates PDP Context Activation in some embodiments. 
         FIG. 59  illustrates Network Requested PDP Context Activation in some embodiments. 
         FIG. 60  illustrates UTRAN to GAN SRNS Relocation Preparation Phase in some embodiments. 
         FIG. 61  illustrates UTRAN to GAN SRNS Relocation Execution Phase in some embodiments. 
         FIG. 62  illustrates GAN to UTRAN SRNS Relocation Preparation Phase in some embodiments. 
         FIG. 63  illustrates GAN to UTRAN SRNS Relocation Execution Phase in some embodiments. 
         FIG. 64  illustrates the GAN architecture in support of the CS Domain control plane in some embodiments. 
         FIG. 65  illustrates the GAN protocol architecture in support of the CS domain user plane in some embodiments. 
         FIG. 66  illustrates the GAN architecture in support of the PS Domain Control Plane in some embodiments. 
         FIG. 67  illustrates the GAN architecture for the PS Domain User Plane in some embodiments. 
         FIG. 68  illustrates the GA-RC sublayer in the UE in some embodiments. 
         FIG. 69  illustrates successful (and unsuccessful) establishment of the GA-RRC Connection when initiated by the UE in some embodiments. 
         FIG. 70  illustrates successful establishment of the GA-RRC Connection when initiated by the network in some embodiments. 
         FIG. 71  shows release of the logical GA-RRC connection between the UE and the GANC in some embodiments. 
         FIG. 72  illustrates the message flow for security mode control in some embodiments. 
         FIG. 73  illustrates core network to UE NAS signaling of some embodiments. 
         FIG. 74  illustrates the UE to core network NAS signaling of some embodiments. 
         FIG. 75  illustrates mobile originated CS call procedure in some embodiments. 
         FIG. 76  illustrates an alternative procedure performed during a mobile originated CS call in some embodiments. 
         FIG. 77  illustrates mobile terminated CS call procedure in some embodiments. 
         FIG. 78  illustrates call clearing initiated by the UE in some embodiments. 
         FIG. 79  illustrates the CS Handover from GERAN to GAN procedure in some embodiments. 
         FIG. 80  illustrates an alternative procedure for CS handover from GERAN to GAN in some embodiments. 
         FIG. 81  illustrates the CS Handover from UTRAN to GAN procedure in some embodiments. 
         FIG. 82  illustrates an alternative procedure for CS handover from UTRAN to GAN using RRC protocol in some embodiments. 
         FIG. 83  illustrates the CS handover from GAN to GERAN procedure in some embodiments. 
         FIG. 84  illustrates the CS handover from GAN to UTRAN procedure in some embodiments. 
         FIG. 85  illustrates the Packet Transport Channel initial activation procedure of some embodiments. 
         FIG. 86  illustrates the transfer of GPRS user data packets via the GAN Packet Transport Channel in some embodiments. 
         FIG. 87  illustrates the scenario when the user equipment deactivates the Packet Transport Channel after the PTC Timer expires in some embodiments. 
         FIG. 88  illustrates the scenario when the user equipment initiates re-activation of the Packet Transport Channel in some embodiments. 
         FIG. 89  illustrates the scenario when the network initiates de-activation of the Packet Transport Channel in some embodiments. 
         FIG. 90  illustrates the scenario when the network initiates re-activation of the Packet Transport Channel in some embodiments. 
         FIG. 91  illustrates the successful user equipment initiated PDP Context Activation procedure in some embodiments. 
         FIG. 92  illustrates the successful Network-Requested PDP Context Activation procedure in some embodiments. 
         FIG. 93  illustrates the successful UE-initiated PDP Context Activation procedure in some embodiments. 
         FIG. 94  illustrates SRNS relocation procedure from UTRAN to GAN for a UE that is in PMM Connected state in some embodiments. 
         FIG. 95  conceptually illustrates a computer system with which some embodiments of the invention are implemented. 
         FIG. 96  illustrates the procedure for implicit PTC de-activation in some embodiments. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the following detailed description of the invention, numerous details, examples, and embodiments of the invention are set forth and described. However, it will be clear and apparent to one skilled in the art that the invention is not limited to the embodiments set forth and that the invention may be practiced without some of the specific details and examples discussed. 
     Throughout the following description, acronyms commonly used in the telecommunications industry for wireless services are utilized along with acronyms specific to the present invention. A table of acronyms used in this application is included in Section X. 
     Some embodiments provide a method of registering a user equipment (UE) in a communication system that includes a licensed wireless communication system and a generic access network (GAN) that has a generic access network controller (GANC). The method sends a register request message from the UE to the GANC that indicates a GAN mode capability of A/Gb only for the UE. When the GANC has a GAN mode capability of A/Gb, the GANC registers the UE with the GAN. When the GANC has a GAN mode capability of Iu only, the GANC rejects the register request message. When the GANC has a GAN mode capability of both A/Gb and Iu, the GANC registers the UE based on a set of GANC mode selection rules that the GANC applies for registering UEs with the GAN. 
     Some embodiments provide a method of activating a packet transport channel (PTC) in a communication system that includes a first licensed wireless communication system and a second generic access network (GAN) that has a generic access network controller (GANC). The GANC is communicatively coupled to the first communication system through a universal mobile telecommunication system (UMTS) terrestrial radio access network (UTRAN) Iu interface. The method sends a GA-PSR activate PTC request message from the GANC to a user equipment (UE). The message comprises a terminal endpoint identifier (TEID) that the GANC assigns to the UE. 
     Some embodiments provide a communication system that includes a first licensed wireless communication system, a second generic access network (GAN) that includes a generic access network controller (GANC). The GANC is communicatively coupled to the first communication system through a universal mobile telecommunication system (UMTS) terrestrial radio access network (UTRAN) Iu interface. The communication system also includes a user equipment (UE). The GANC includes a UDP protocol layer and a GTP-U protocol layer over the UDP protocol layer of the GANC. The UE includes a UDP protocol layer and a GTP-U protocol layer over said UDP protocol layer of the UE. The UDP protocol layer of the GANC is communicatively coupled to the UDP protocol layer of the UE. The GTP-U protocol layer of the GANC is communicatively coupled to the GTP-U protocol layer of the UE. 
     Several more detailed embodiments of the invention are described in sections below. Specifically, Section I describes the overall integrated communication system in which some embodiments are incorporated. The discussion in Section I is followed by a discussion of the functional entities of some embodiments in Section II. Next, Section III describes the control and user plane architecture of some embodiments. Section IV then describes the generic access network (GAN) security mechanism of some embodiments. 
     Next, Section V describes high level procedures such as discovery, registration, authentication, handover, etc. of some embodiments. Section VI then describes the configuration information of some embodiments. Next, identifiers used in GAN are presented in Section VII. An alternative embodiment that utilizes the same protocol for both voice and data services is disclosed in Section VIII. The discussion is followed by Section IX description of a computer system with which some embodiments of the invention are implemented. Finally, Section X lists the abbreviations used. 
     I. Overall System 
     A. Integrated Communication Systems (ICS) 
       FIG. 1  illustrates an integrated communication system (ICS) architecture  100  in accordance with some embodiments of the present invention. ICS architecture  100  enables user equipment (UE)  102  to access a voice and data network  165  via either a licensed air interface  106  or an ICS interface  110  through which components of a mobile core network  165  are alternatively accessed. In some embodiments, a communication session includes voice services, data services, or both. 
     The mobile core network  165  includes one or more Home Location Registers (HLRs)  150  and databases  145  for subscriber authentication and authorization. Once authorized, the UE  102  may access the voice and data services of the mobile core network  165 . In order to provide such services, the mobile core network  165  includes a mobile switching center (MSC)  160  for providing access to the voice services. Data services are provided for through a Serving GPRS (General Packet Radio Service) Support Node (SGSN)  155  in conjunction with a gateway such as the Gateway GPRS Support Node (GGSN)  157 . 
     The SGSN  155  is typically responsible for delivering data packets from and to the GGSN  157  and the user equipment within the geographical service area of the SGSN  155 . Additionally, the SGSN  155  may perform functionality such as mobility management, storing user profiles, and storing location information. However, the actual interface from the mobile core network  165  to various external data packet services networks (e.g., public Internet) is facilitated by the GGSN  157 . As the data packets originating from the user equipment typically are not structured in the format with which to access the external data networks, it is the role of the GGSN  157  to act as the gateway into such packet services networks. In this manner, the GGSN  157  provides addressing for data packets passing to and from the UE  102  and the external packet services networks (not shown). Moreover, as the user equipment of a licensed wireless network traverses multiple service regions and thus multiple SGSNs, it is the role of the GGSN  157  to provide a static gateway into the external data networks. 
     In the illustrated embodiment, components common to a UMTS Terrestrial Radio Access Network (UTRAN) based cellular network  185  are depicted that include multiple base stations referred to as Node Bs  180  (of which only one is shown for simplicity) that facilitate wireless communication services for various user equipment  102  via respective licensed radio links  106  (e.g., radio links employing radio frequencies within a licensed bandwidth). However, one of ordinary skill in the art will recognize that in some embodiments, the licensed wireless network may include other licensed wireless networks such as the GSM/EDGE Radio Access Network (GERAN). An example of a system using A and Gb interfaces to access GERAN is shown in  FIG. 3  below. 
     The licensed wireless channel  106  may comprise any licensed wireless service having a defined UTRAN or GERAN interface protocol (e.g., Iu-cs and Iu-ps interfaces for UTRAN or A and Gb interfaces for GERAN) for a voice/data network. The UTRAN  185  typically includes at least one Node B  180  and a Radio Network Controller (RNC)  175  for managing the set of Node Bs  180 . Typically, the multiple Node Bs  180  are configured in a cellular configuration (one per each cell) that covers a wide service area. 
     Each RNC  175  communicates with components of the core network  165  through a standard radio network controller interface such as the Iu-cs and Iu-ps interfaces depicted in  FIG. 1 . For example, a RNC  175  communicates with MSC  160  via the UTRAN Iu-cs interface for circuit switched voice services. Additionally, the RNC  175  communicates with SGSN  155  via the UTRAN Iu-ps interface for packet data services through GGSN  157 . Moreover, one of ordinary skill in the art will recognize that in some embodiments, other networks with other standard interfaces may apply. For example, the RNC  175  in a GERAN network is replaced with a Base Station Controller (BSC) that communicates voice to the MSC  160  via an A interface and the BSC communicates data to the SGSN via a Gb interface of the GERAN network. 
     In some embodiments of the ICS architecture, the user equipment  102  use the services of the mobile core network (CN)  165  via a second communication network facilitated by the ICS access interface  110  and a Generic Access Network Controller (GANC)  120  (also referred to as a Universal Network Controller or UNC). 
     In some embodiments, the voice and data services over the ICS access interface  110  are facilitated via an access point  114  communicatively coupled to a broadband IP network  116 . In some embodiments, the access point  114  is a generic wireless access point that connects the user equipment  102  to the ICS network through an unlicensed wireless network  118  created by the access point  114 . 
     The signaling from the UE  102  is passed over the ICS access interface  110  to the GANC  120 . After the GANC  120  performs authentication and authorization of the subscriber, the GANC  120  communicates with components of the mobile core network  165  using a radio network controller interface that is the same or similar to the radio network controller interface of the UTRAN described above, and includes a UTRAN Iu-cs interface for circuit switched voice services and a UTRAN Iu-ps interface for packet data services (e.g., GPRS). In this manner, the GANC  120  uses the same or similar interface to the mobile core network as a UTRAN Radio Network Subsystem (e.g., the Node B  180  and RNC  175 ). 
     In some embodiments, the GANC  120  communicates with other system components of the ICS system through one or more of several other interfaces, which are (1) “Up”, (2) “Wm”, (3) “D′/Gr′”, (4) “Gn′”, and (5) “S1”. The “Up” interface is the interface between the UE  102  and the GANC  120 . The “Wm” interface is a standardized interface between the GANC  120  and an Authorization, Authentication, and Accounting (AAA) Server  170  for authentication and authorization of the UE  102  into the ICS. The “D′/Gr′” interface is the standard interface between the AAA server  170  and the HLR  160 . Optionally, some embodiments use the “Gn′” interface which is a modified interface for direct communications with the data services gateway (e.g., GGSN) of the core licensed network. Some embodiments optionally include the “S1” interface. In these embodiments, the “S1” interface provides an authorization and authentication interface from the GANC  120  to an AAA  140  server. In some embodiments, the AAA server  140  that supports the “S1” interface and the AAA server  170  that supports Wm interface may be the same. More details of the “S1” interface are described in U.S. Patent application Ser. No. 11/349,025, entitled “Service Access Control Interface for an Unlicensed Wireless Communication System”, filed Feb. 6, 2006, now issued as U.S. Pat. No. 7,283,822. 
     In some embodiments, the UE  102  must register with the GANC  120  prior to accessing ICS services. Registration information of some embodiments includes a subscriber&#39;s International Mobile Subscriber Identity (IMSI), a Media Access Control (MAC) address, and a Service Set Identifier (SSID) of the serving access point as well as the cell identity from the GSM or UTRAN cell upon which the UE  102  is already camped. In some embodiments, the GANC  120  may pass this information to the AAA server  140  to authenticate the subscriber and determine the services (e.g., voice and data) available to the subscriber. If approved by the AAA  140  for access, the GANC  120  will permit the UE  102  to access voice and data services of the ICS system. 
     These voice and data services are seamlessly provided by the ICS to the UE  102  through the various interfaces described above. In some embodiments, when data services are requested by the UE  102 , the ICS uses the optional Gn′ interface for directly communicating with a GGSN  157 . The Gn′ interface allows the GANC  120  to avoid the overhead and latency associated with communicating with the SGSN  155  over the Iu-ps interface of the UTRAN or the Gb interface of the GSM core networks prior to reaching the GGSN  157 . 
     In some other embodiments, the access point  114  is a Femtocell access point (FAP). The FAP facilitates short-range licensed wireless communication sessions  118  that operate independent of the licensed communication session  106 . In case of the Femtocell, the user equipment  102  connects to the ICS network through the short-range licensed wireless network  118  created by the FAP  114 . Signals from the FAP are then transmitted over the broadband IP network  116 . 
     B. Applications of ICS 
     An ICS provides scalable and secure interfaces into the core service network of mobile communication systems.  FIG. 2  illustrates several applications of an ICS in some embodiments. As shown, homes, offices, hot spots, hotels, and other public and private places  205  are connected to one or more network controllers  210  (such as the GANC  120  shown in  FIG. 1 ) through the Internet  215 . The network controllers in turn connect to the mobile core network  220  (such as the core network  165  shown in  FIG. 1 ). 
       FIG. 2  also shows several user equipments. These user equipments are just examples of user equipments that can be used for each application. Although in most examples only one of each type of user equipments is shown, one of ordinary skill in the art would realize that other type of user equipments can be used in these examples without deviating from the teachings of the invention. Also, although only of each type of access points, user equipment, or network controllers are shown, many such access points, user equipments, or network controllers may be employed in  FIG. 2 . For instance, an access point may be connected to several user equipment, a network controller may be connected to several access points, and several network controllers may be connected to the core network. The following sub-sections provide several examples of services that can be provided by an ICS. 
     1. Wi-Fi 
     A Wi-Fi access point  230  enables a dual-mode cellular/Wi-Fi UEs  260 - 265  to receive high-performance, low-cost mobile services when in range of a home, office, or public Wi-Fi network. With dual-mode UEs, subscribers can roam and handover between licensed wireless communication system and Wi-Fi access and receive a consistent set of services as they transition between networks. 
     2. Femtocells 
     A Femtocell enables user equipments, such as standard mobile stations  270  and wireless enabled computers  275  shown, to receive low cost services using a short-range licensed wireless communication sessions through a FAP  235 . 
     3. Terminal Adaptors 
     Terminal adaptors  240  allow incorporating fixed-terminal devices such as telephones  245 , Faxes  250 , and other equipments that are not wireless enabled within the ICS. As long as the subscriber is concerned, the service behaves as a standard analog fixed telephone line. The service is delivered in a manner similar to other fixed line VoIP services, where a UE is connected to the subscriber&#39;s existing broadband (e.g., Internet) service. 
     4. WiMAX 
     Some licensed wireless communication system operators are investigating deployment of WiMAX networks in parallel with their existing cellular networks. A dual mode cellular/WiMAX UE  290  enables a subscriber to seamlessly transition between a cellular network and such a WiMAX network. 
     5. SoftMobiles 
     Connecting laptops  280  to broadband access at hotels and Wi-Fi hot spots has become popular, particularly for international business travelers. In addition, many travelers are beginning to utilize their laptops and broadband connections for the purpose of voice communications. Rather than using mobile phones to make calls and pay significant roaming fees, they utilize SoftMobiles (or SoftPhones) and VoIP services when making long distance calls. 
     To use a SoftMobile service, a subscriber would place a USB memory stick  285  with an embedded SIM into a USB port of their laptop  280 . A SoftMobile client would automatically launch and connect over IP to the mobile service provider. From that point on, the subscriber would be able to make and receive mobile calls as if she was in her home calling area. 
     Several examples of Integrated Communication Systems (ICS) are given in the following sub-sections. A person of ordinary skill in the art would realize that the teachings in these examples can be readily combined. For instance, an ICS can be an IP based system and have an A/Gb interface towards the core network while another ICS can have a similar IP based system with an Iu interface towards the core network. 
     C. Integrated Systems with A/GB and/or Iu Interfaces Towards the Core Network 
       FIG. 3  illustrates the A/Gb-mode Generic Access Network (GAN) functional architecture of some embodiments. The GAN includes one or more Generic Access Network Controllers (GANC)  310  and one or more generic IP access networks  315 . One or more UEs  305  (one is shown for simplicity) can connect to a GANC  310  through a generic IP access network  315 . The GANC  310  has the capability to appear to the core network  325  as a GSM/EDGE Radio Access Network (GERAN) Base Station Controller (BSC). The GANC  310  includes a Security Gateway (SEGW)  320  that terminates secure remote access tunnels from the UE  305 , providing mutual authentication, encryption and data integrity for signaling, voice and data traffic. 
     The generic IP access network  315  provides connectivity between the UE  305  and the GANC  310 . The IP transport connection extends from the GANC  310  to the UE  305 . A single interface, the Up interface, is defined between the GANC  310  and the UE  305 . 
     The GAN co-exists with the GERAN and maintains the interconnections with the Core Network (CN)  325  via the standardized interfaces defined for GERAN. These standardized interfaces include the A interface to Mobile Switching Center (MSC)  330  for circuit switched services, Gb interface to Serving GPRS Support Node (SGSN)  335  for packet switched services, Lb interface to Serving Mobile Location Center (SMLC)  350  for supporting location services, and an interface to Cell Broadcast Center (CBC)  355  for supporting cell broadcast services. The transaction control (e.g. Connection Management, CC, and Session Management, SM) and user services are provided by the core network (e.g. MSC/VLR and the SGSN/GGSN). 
     As shown, the SEGW  320  is connected to a AAA server  340  over the Wm interface. The AAA server  340  is used to authenticate the UE  305  when it sets up a secure tunnel. Some embodiments require only a subset of the Wm functionalities for the GAN application. In these embodiments, as a minimum the GANC-SEGW shall support the Wm authentication procedures. 
       FIG. 4  illustrates the Iu-mode Generic Access Network (GAN) functional architecture of some embodiments. The GAN includes one or more Generic Access Network Controllers (GANC)  410  and one or more generic IP access networks  415 . One or more UEs  405  (one is shown for simplicity) can be connected to a GANC  410  through a generic IP access network  415 . In comparison with the GANC  310 , the GANC  410  has the capability to appear to the core network  425  as a UMTS Terrestrial Radio Access Network (UTRAN) Radio Network Controller (RNC). In some embodiments, the GANC has the expanded capability of supporting both the Iu and A/Gb interfaces to concurrently support both Iu-mode and A/Gb-mode UEs. Similar to the GANC  310 , the GANC  410  includes a Security Gateway (SEGW)  420  that terminates secure remote access tunnels from the UE  405 , providing mutual authentication, encryption and data integrity for signaling, voice and data traffic. 
     The generic IP access network  415  provides connectivity between the UE  405  and the GANC  410 . The IP transport connection extends from the GANC  410  to the UE  405 . A single interface, the Up interface, is defined between the GANC  410  and the UE  405 . Functionality is added to this interface, over the UP interface shown in  FIG. 3  to support the Iu-mode GAN service. 
     The GAN co-exists with the UTRAN and maintains the interconnections with the Core Network (CN)  425  and via the standardized interfaces defined for UTRAN. These standardized interfaces include the Iu-cs interface to Mobile Switching Center (MSC)  430  for circuit switched services, Iu-ps interface to Serving GPRS Support Node (SGSN)  435  for packet switched services, Iu-pc interface to Serving Mobile Location Center (SMLC)  450  for supporting location services, and Iu-bc interface to Cell Broadcast Center (CBC)  455  for supporting cell broadcast services. The transaction control (e.g. Connection Management, CC, and Session Management, SM) and user services are provided by the core network (e.g. MSC/VLR and the SGSN/GGSN). 
     As shown, the SEGW  420  is connected to a AAA server  440  over the Wm interface. The AAA server  440  is used to authenticate the UE  405  when it sets up a secure tunnel. Some embodiments require only a subset of the Wm functionalities for the Iu mode GAN application. In these embodiments, as a minimum the GANC-SEGW shall support the Wm authentication procedures. 
     D. ATM and IP Based Architectures 
     In some embodiments, the system uses Asynchronous Transfer Mode (ATM) based Iu (Iu-cs and Iu-ps) interfaces towards the CN. In some embodiments, the system architecture can also support an IP based Iu (Iu-cs and Iu-ps) interface towards the CN. The following two sub-sections describe examples of these architectures for Femtocell. 
     A person of ordinary skill in the art would realize that the same examples can be readily applied to other types of ICS. For instance, these examples can be used when the ICS access interface  110  (shown in  FIG. 1 ) uses unlicensed frequencies (instead of Femtocell&#39;s licensed frequencies), the access point  114  is a generic WiFi access point (instead of a FAP), etc. Also, a person of ordinary skill in the art would realize that the same examples can be readily implemented using A/Gb interfaces (described above) instead of Iu interfaces. 
       FIG. 5  illustrates the basic elements of a Femtocell system architecture with Asynchronous Transfer Mode (ATM) based Iu (Iu-cs and Iu-ps) interfaces towards the CN in some embodiments. These elements include the user equipment (UE)  505 , the FAP  510 , and the Generic Access Network Controller (GANC)  515 , and the Access Point Management SYSTEM (AMS)  570 . 
     For simplicity, only one UE and one FAP are shown. However, each GANC can support multiple FAPs and each FAP in turn can support multiple UEs. As shown, the GANC  515  includes an IP Network Controller (INC)  525 , a GANC Security Gateway (SeGW)  530 , a GANC Signaling Gateway  535 , a GANC Media Gateway (MGW)  540 , an ATM Gateway ( 545 ). Elements of the Femtocell are described further below. 
       FIG. 6  illustrates the basic elements of a Femtocell system architecture with an IP based Iu (Iu-cs and Iu-ps) interface towards the CN in some embodiments. For simplicity, only one UE and one FAP are shown. However, each GANC can support multiple FAPs and each FAP in turn can support multiple UEs. This option eliminates the need for the GANC Signaling gateway  535  and also the ATM gateway  545 . Optionally for IP based Iu interface, the GANC Media Gateway  540  can also be eliminated if the R4 MGW  605  in the CN can support termination of voice data i.e. RTP frames as defined in “IETF RFC 3267—Real-Time Transport Protocol (RTP) Payload Format and File Storage Format for the Adaptive Multi-Rate (AMR) and Adaptive Multi-Rate Wideband (AMR-WB) Audio Codecs”, “RFC 3267”. 
     Also shown in  FIGS. 5 and 6  are components of the licensed wireless communication systems. These components are 3G MSC  550 , 3G SGSN  555 , and other Core Network System (shown together)  565 . The 3G MSC  550  provides a standard Iu-cs interface towards the GANC. Another alternative for the MSC is shown in  FIG. 6 . As shown, the MSC  650  is split up into a MSS (MSC Server)  675  for Iu-cs based signaling and MGW  680  for the bearer path. R4 MSC  650  is a release 4 version of a 3G MSC with a different architecture i.e. R4 MSC is split into MSS for control traffic and a MGW for handling the bearer. A similar MSC can be used for the ATM architecture of  FIG. 5 . Both architectures shown in  FIGS. 5 and 6  are also adaptable to use any future versions of the MSC. 
     The 3G SGSN  555  provides packet services (PS) via the standard Iu-ps interface. The SGSN connects to the INC  525  for signaling and to the SeGW  530  for PS data. The AAA server  560  communicates with the SeGW  530  and supports the EAP-AKA and EAP-SIM procedures used in IKEv2 over the Wm interface and includes a MAP interface to the HLR/AuC. In some embodiments, this system also supports the enhanced service access control functions over the S1 interface. 
     II. Functional Entities 
     A. User Equipment 
     The UE  405  contains the functions that are required to access the Iu-mode GAN. In some embodiments, the UE additionally contains that are required to access the A/Gb-mode GAN. In some embodiments, the User Equipment (UE)  305  is a dual mode (e.g., GSM and unlicensed radios) handset device with capability to switch between the two modes. The user equipment can support either Bluetooth® or IEEE 802.11 protocols. In some embodiments, the UE supports an IP interface to the access point. In these embodiments, the IP connection from the GANC extends all the way to the UE. In some other embodiments, the User Equipment (UE)  305  is a standard 3G handset device operating over licensed spectrum of the provider. 
     In some embodiments, the user equipment includes a cellular telephone, smart phone, personal digital assistant, or computer equipped with a subscriber identity mobile (SIM) card for communicating over the licensed or unlicensed wireless networks. Moreover, in some embodiments the computer equipped with the SIM card communicates through a wired communication network. 
     Alternatively, in some embodiments the user equipment includes a fixed wireless device providing a set of terminal adapter functions for connecting Integrated Services Digital Network (ISDN), Session Initiation Protocol (SIP), or Plain Old Telephone Service (POTS) terminals to the ICS. Application of the present invention to this type of device enables the wireless service provider to offer the so-called landline replacement service to users, even for user locations not sufficiently covered by the licensed wireless network. Moreover, some embodiments of the terminal adapters are fixed wired devices for connecting ISDN, SIP, or POTS terminals to a different communication network (e.g., IP network) though alternate embodiments of the terminal adapters provide wireless equivalent functionality for connecting through unlicensed or licensed wireless networks. 
     B. Generic Access Network Controller (GANC) 
     The core network  425  interacts with the GANC  410  as though it was an RNC. The generic IP access network  415  provides connectivity between the GANC  410  and the UE  405 . The GANC  410  entity inter-works between the Iu interfaces and a generic IP access network, using the control plane and user plane functionalities. The control plane functionality is utilized for call control signaling and the user plane functionality is utilized for information transfer (e.g., voice or data). In some embodiments, the GANC has the extended capability to also inter-work with GERAN A/Gb interfaces. 
     Some embodiments of the above mentioned devices, such as the user equipment, FAP, or GANC, include electronic components, such as microprocessors and memory (not shown), that store computer program instructions for executing wireless protocols for managing voice and data services in a machine-readable or computer-readable medium as further described below in the section labeled “Computer System”. Examples of machine-readable media or computer-readable media include, but are not limited to magnetic media such as hard disks, memory modules, magnetic tape, optical media such as CD-ROMS and holographic devices, magneto-optical media such as optical disks, and hardware devices that are specially configured to store and execute program code, such as application specific integrated circuits (ASICs), programmable logic devices (PLDs), ROM, and RAM devices. Examples of computer programs or computer code include machine code, such as produced by a compiler, and files containing higher-level code that are executed by a computer, an electronic component, or a microprocessor using an interpreter. 
     III. Control and User Plane Architecture 
     In some embodiments, the Iu interface includes support for both Asynchronous Transfer Mode (ATM) and IP-based signaling and user data transport mechanisms. The following sections describe the control and user plane architectures for the Circuit Switched (CS) domain and Packet Switched (PS) domain of some embodiments. 
     A. Circuit Switched (CS) Domain 
     1. CS Domain—Control Plane 
       FIG. 7  illustrates the GAN architecture in support of the CS Domain control plane in some embodiments. The figure shows different protocol layers for the UE  705 , Generic IP Network  710 , GANC  715 , and MSC  720 .  FIG. 7  also shows the two interfaces Up  725  and Iu-cs  730 . The main features of the GAN CS domain control plane architecture are as follows. The underlying Access Layers  735  and Transport IP layer  740  provide the generic IP connectivity between the UE  705  and the GANC  715 . The IPSec layer  745  provides encryption and data integrity between the UE  705  and GANC  715 . The Remote IP layer  750  is the ‘inner’ IP layer for IPSec tunnel mode and is used by the UE  705  to be addressed by the GANC  715 . The Remote IP layer  750  is configured during the IPSec connection establishment. 
     In some embodiments, a single TCP connection is used to provide reliable transport for both the GA-RC and GA-CSR signaling between the UE  705  and GANC  715 . The TCP connection is managed by GA-RC and is transported using the Remote IP layer. Non-Access Stratum (NAS) protocols, such as MM  760  and above, are carried transparently between the UE  705  and MSC  720 . The Generic Access Resource Control (GA-RC) protocol manages the Up session, including the GAN discovery and registration procedures. The GA-RC protocol (described in clause 8.1.4 of “Generic access to the A/Gb interface; Stage 2”, 3GPP TS 43.318 standard) is extended to include support for the selection of either A/Gb mode or Iu mode GAN. 
     The Generic Access Circuit Switched Resource (GA-CSR) protocol supports UMTS-specific requirements as well as GERAN-specific requirements. The GANC  715  terminates the GA-CSR protocol and inter-works it to the RANAP 755 protocol over the Iu-cs  730  interface. In some embodiments, the Iu-cs signaling transport layers  765  are per “UTRAN Iu interface signalling transport”, 3GPP TS 25.412 standard, hereinafter “3GPP TS 25.412”. 
     a) Alternative Architectures for Cs Domain—Control Plane 
     The embodiment shown in  FIG. 7  is just one alternative for implementing the CS domain control plane architecture in which a UE  705  and a Generic IP Network  710  are used to connect a subscriber using the UE to the MSC  720  through the GANC  715 . A person of ordinary skill in the art would realize that the teachings of the invention can be applied for other user equipment and access points (such as the ones described in  FIG. 2 ). 
     For instance,  FIG. 8  illustrates the CS domain control plane architecture of some embodiments. As shown, the GANC and MSC in  FIG. 8  are similar to the GANC and MSC shown in  FIG. 7 . In  FIG. 8 , the local node in which the subscriber is located is represented as a black box (referred to as Local Node  805 ). Different embodiments utilize different equipments in order to connect a subscriber located in the Local Node  805  with the MSC  720  through the GANC  715 . For instance, in the embodiment shown in  FIG. 7 , a UE  705  and a Generic IP Network are used  710 .  FIG. 9  illustrates another embodiment in which a UE  905 , a Femtocell access point (FAP)  910 , and a Generic IP Network  915  are used to connect the Local Node  805  with the MSC  720  through the GANC  715 . 
     As shown, the protocol layers of the GANC  880 - 885  are communicatively coupled (shown with arrows  845 - 850  respectively) with their corresponding layers in the Generic IP Network  915 . Similarly, the GANC layers  855 - 875  are communicatively coupled (shown with arrows  820 - 840  respectively) with their corresponding layers in the FAP  910 . Also the MM layer  890  and CC/CS/SMS layers  895  of the MSC  720  are transparently connected (shown with arrows  810 - 815  respectively) to their corresponding layers in the UE  905 . Using this technique, the FAP similar to the FAP  235  shown in  FIG. 2  can be utilized to connect a UE (such as UEs  270 - 275 ) to the wireless core network  220  through a network controller  210 . A person of ordinary skill in the art would be able to apply the technique shown in  FIGS. 8 and 9  to communicatively couple any user equipment, access points, terminal adaptors, SoftMobiles, etc. (such as the ones shown in  FIG. 2 ) to an integrated communication system (ICS) that uses a multi-layer CS domain control architecture as shown in  FIG. 7 . 
     b) CS Domain—Control Plane—UE Architecture 
       FIG. 10  illustrates the UE architecture for the CS domain control plane. As shown, the architecture includes support for GERAN, UTRAN, and both A/Gb mode GAN and Iu mode GAN. The main features of the UE CS Domain Control Plane architecture shown in  FIG. 10  are as follows. The GERAN RR-SAP interface  1015  to the GSM-MM layer  1005  is preserved identically for both GERAN and A/Gb-mode GAN access. Likewise, the UTRAN RR-SAP interface  1020  to the GSM-MM layer  1005  is preserved identically for both UTRAN and Iu-mode GAN access. An access mode switch  1010  is provided to switch between GERAN/UTRAN, A/GB-mode GAN and Iu-mode GAN modes. GA-CSR/GA-RC  1025  peers directly with the UTRAN RRC  1030  and GERAN RRC  1035  layers to provide coordination for roving and handover. As shown in  FIG. 10 , GA-CSR/GA-RC  1025 , UTRAN RRC  1030 , and GERAN RRC  1035  interface through a set of service access interfaces (SAPs)  1040 . 
     2. CS Domain—User Plane 
       FIG. 11  illustrates the GAN protocol architecture in support of the CS domain user plane in some embodiments. The figure shows different protocol layers for the UE  1105 , Generic IP Network  1110 , GANC  1115 , and MSC  1120 .  FIG. 11  also shows the two interfaces Up  1125  and Iu-cs  1130 . The main features of the GAN CS domain user plane architecture are as follows. The underlying Access Layers  1135  and Transport IP layer  1140  provide the generic connectivity between the UE  1105  and the GANC  1115 . The IPSec layer  1145  provides encryption and data integrity. The CS user plane data transport over the Up interface  1125  is the same as the CS user plane for A/Gb-mode GAN (i.e., using the Real Time Protocol, RTP, per IETF RFC 3267. The GANC  1115  interworks the CS domain user plane between RTP/UDP and the Iu User Plane (Iu-UP) protocol on the Iu-cs interface  1130 . In some embodiments, the Iu-cs Data transport layers  1165  are per 3GPP TS 25.414 standard. 
     A person of ordinary skill in the art would realize that other user equipments, access point, terminal adaptor, SoftMobiles, etc. can be connected to the core network through a GANC. For instance,  FIG. 12  illustrates the CS domain, user plane protocol architecture of a UE  1205 , a Femtocell access point (FAP)  1210 , and Generic IP Network  1215 . Using the technique described in conjunction with  FIGS. 8 and 9 , a person of ordinary skill in the art would be able to replace the UE  1105  and Generic IP Network  1110  shown in  FIG. 11  with the UE  1205 , FAP  1210 , and Generic IP Network  1215  to connect the Femtocell UE  1205  to the core network through the GANC. Similarly, other types of UE, access points, terminal adaptors, SoftMobiles, etc. can be connected to the core network through the GANC. 
     b) CS Domain—User Plane—UE Architecture 
       FIG. 13  illustrates the UE architecture for the CS domain user plane in some embodiments. As shown, the architecture includes support for both A/Gb mode and Iu mode GAN  1305 , as well as GERAN  1310 , and UTRAN  1315 . The RFC 3267 AMR Processing layer  1320  is utilized for connecting the GAN RTP/UDP/IP layers  1325  to the AMR Audio Processing layer  1330  through the CS User Plane Routing Service layer  1335 , which routes CS user plane data to and from the selected access network; i.e., GERAN, UTRAN, or GAN. The RFC 3267 AMR Processing layer  1320  is not used when connecting to the CS Data Processing layer  1340 ; i.e., in the case of circuit switched data, as opposed to circuit switched voice. 
     B. Packet Switched (PS) Domain 
     1. PS Domain—Control Plane 
       FIG. 14  illustrates the GAN architecture in support of the PS Domain Control plane. The figure shows different protocol layers for the UE  1405 , Generic IP Network  1410 , GANC  1415 , SGSN  1420 .  FIG. 14  also shows the two interfaces Up  1425  and Iu-ps  1430 . The main features of the GAN PS domain control plane architecture shown in  FIG. 14  are as follows. The underlying Access Layers  1435  and Transport IP layer  1440  provide the generic connectivity between the UE  1405  and the GANC  1415 . The IPSec layer  1445  provides encryption and data integrity. TCP  1450  provides reliable transport for the GA-PSR between UE  1405  and GANC  1415 . The GA-RC manages the IP connection, including the GAN registration procedures. The Generic Access Packet Switched Resource (GA-PSR) protocol supports UMTS-specific requirements. 
     The GANC  1415  terminates the GA-PSR protocol and inter-works it to the RANAP protocol  1455  over the Iu-ps interface  1430 . NAS protocols  1460 , such as for GMM, SM and SMS, are carried transparently between the UE  1405  and SGSN  1420 . In some embodiments, the Iu-ps signaling transport layers  1465  are per 3GPP TS 25.412. 
     A person of ordinary skill in the art would realize that other user equipments, access point, terminal adaptor, SoftMobiles, etc. can be connected to the core network through a GANC. For instance,  FIG. 15  illustrates the PS domain, control plane protocol architecture of a UE  1505 , a Femtocell access point (FAP)  1510 , and Generic IP Network  1515 . Using the technique described in conjunction with  FIGS. 8 and 9 , a person of ordinary skill in the art would be able to replace the UE  1405  and Generic IP Network  1410  shown in  FIG. 11  with the UE  1505 , FAP  1510 , and Generic IP Network  1515  to connect the Femtocell UE  1505  to the core network through the GANC. Similarly, other types of UE, access points, terminal adaptors, SoftMobiles, etc. can be connected to the core network through the GANC. 
     c) PS Domain—Control Plane—UE Architecture 
       FIG. 16  illustrates the UE architecture for the PS domain control plane in some embodiments. As shown, the architecture includes support for both A/Gb mode and Iu mode GAN, as well as GERAN and UTRAN. The main features of the UE PS Domain Control Plane architecture shown in  FIG. 16  are as follows. The GERAN GRR-SAP interface  1615  and GERAN GMMRR-SAP interface  1617  to the GMM layer  1605  is preserved identically for both GERAN and A/Gb-mode GAN access. Likewise, the UTRAN RABMAS-SAP interface  1620  and UTRAN GMMAS-SAP interface  1622  to the GMM layer  1605  is preserved identically for both UTRAN and Iu-mode GAN access. An access mode switch  1610  is provided to switch between GERAN/UTRAN, A/GB-mode GAN and Iu-mode GAN modes. GA-PSR/GA-RC  1625  peers directly with the UTRAN RRC  1630  and GERAN RRC  1635  layers to provide coordination for roving and handover. As shown in  FIG. 16 , GA-PSR/GA-RC  1625 , UTRAN RRC  1630 , and GERAN RRC  1635  interface through a set of service access interfaces (SAPs)  1640 . 
     2. PS Domain—User Plane 
       FIG. 17  illustrates the GAN architecture for the PS Domain User Plane in some embodiments. The figure shows different protocol layers for the UE  1705 , Generic IP Network  1710 , GANC  1715 , SGSN  1720 .  FIG. 17  also shows the two interfaces Up  1725  and Iu-ps  1730 . The main features of the GAN PS domain user plane architecture shown in  FIG. 17  are as follows. The underlying Access Layers  1735  and Transport IP layer  1740  provide the generic connectivity between the UE  1705  and the GANC  1715 . The IPSec layer  1745  provides encryption and data integrity. 
     GA-PSR is extended to include support for the GTP-U G-PDU message format to transport PS User Data (e.g., IP packets), rather than LLC PDUs as in A/Gb mode GAN. As shown in  FIG. 17 , user data in GTP-U G-PDU messages may be carried transparently between the UE  1705  and core network through the SGSN to the GGSN. In some embodiments, the Iu-ps data transport lower layers  1765  are per 3GPP TS 25.414 standard. 
       FIG. 18  illustrates an alternative GAN PS domain user plane configuration which is supported by the Up interface procedures of some embodiments. In this configuration, the GANC  1815  terminates the Up interface GTP-U tunnel with the UE  1805  and also terminates the separate Iu-ps GTP-U tunnel to the SGSN  1820 . The GANC  1815  relays the PS user data between the Up interface GTP-U tunnel and the associated Iu-ps interface GTP-U tunnel to allow the PS user data to flow between the UE and the SGSN. 
     This configuration minimizes the number of active GTP-U “paths” presented to the core network; i.e., the SGSN may be limited in the number of RNCs with which it can concurrently exchange PS user data (e.g., today, there can be no more than 4096 RNCs in a given PLMN). It may not be able to support—without a software upgrade, for example—concurrent communication with hundreds of thousands of UEs as would be required if the GTP-U tunnels were from UE to SGSN. Terminating the Iu-ps GTP-U tunnels on the GANC avoids this potential SGSN limitation. In some embodiments, the Iu-ps data transport lower layers  1865  are per 3GPP TS 25.414 standard. 
     A person of ordinary skill in the art would realize that other user equipments, access point, terminal adaptor, SoftMobiles, etc. can be connected to the core network through a GANC. For instance,  FIG. 19  illustrates the PS domain, user plane protocol architecture of a UE  1905 , a Femtocell access point (FAP)  1910 , and Generic IP Network  1915 . Using the technique described in conjunction with  FIGS. 8 and 9 , a person of ordinary skill in the art would be able to replace the UE  1805  and Generic IP Network  1810  shown in  FIG. 11  with the UE  1905 , FAP  1910 , and Generic IP Network  1915  to connect the Femtocell UE  1905  to the core network through the GANC. Similarly, other types of UE, access points, terminal adaptors, SoftMobiles, etc. can be connected to the core network through the GANC. 
     a) PS Domain—User Plane—UE Architecture 
       FIG. 20  illustrates the UE architecture for the PS domain user plane in some embodiments. As shown, the architecture includes support for both A/Gb mode and Iu mode GAN  2005 , as well as GERAN  2010 , and UTRAN  2015 . An access mode switch  2020  is provided to switch between GERAN/UTRAN, A/GB-mode GAN and Iu-mode GAN modes. 
     C. GA-RC (Generic Access Resource Control) 
     The GA-RC protocol provides a resource management layer, with the following functions. Discovery and registration with GANC, registration update with GANC, application level keep-alive with GANC; and support for identification of the AP being used for GAN access. 
     1. States of the GA-RC Sub-Layer 
       FIG. 21  illustrates the state diagram for generic access in the UE in some embodiments. As shown, the GA-RC sub-layer in the UE can be in one of two states: GA-RC-DEREGISTERED  2105  or GA-RC-REGISTERED  2110 . The following outcomes are possible when switching (shown by arrow  2112 ) the serving RR to Iu-mode GAN: (1) Transition to GA-CSR-IDLE  2115  and GA-PSR-IDLE  2120  (i.e., if the UE is idle during the transition), (2) Transition to GA-CSR-CONNECTED  2125  and GA-PSR-IDLE  2130  (i.e., due to CS handover or relocation), (3) Transition to GA-CSR-IDLE  2115  and GA-PSR-CONNECTED  2130  (i.e., due to PS handover or relocation), (4) Transition to GA-CSR-CONNECTED  2125  and GA-PSR-CONNECTED  2130  (i.e., due to dual transfer mode handover or CS+PS relocation). The switch of the serving RR from GAN to GERAN/UTRAN RRC (shown by arrow  2135 ) may occur when the UE is in any combination of the GA-CSR and GA-PSR states. 
     In the GA-RC-DEREGISTERED state  2105 , the UE may be in a GAN coverage area; however, the UE has not registered successfully with the GANC. The UE may initiate the GAN Registration procedure when in the GA-RC-DEREGISTERED state  2105 . The UE returns to GA-RC-DEREGISTERED state  2105  on loss of TCP or IPSec connection or on execution of the GAN De-registration procedure. 
     In the GA-RC-REGISTERED state  2110 , the UE is registered with the Serving GANC. The UE has an IPSec tunnel and a TCP connection established to the Serving GANC through which the UE may exchange GA-RC, GA-CSR, and GA-PSR signaling messages with the GANC. 
     While the UE remains in the GA-RC-REGISTERED state  2110  it performs application level keep-alive with the GANC. In the GA-RC-REGISTERED state  2110 , the UE may be in either UTRAN/GERAN mode or GAN mode. The UE may either (1) be camped on GERAN or UTRAN and idle, (2) be active in GERAN or UTRAN (e.g., a GSM RR or a UTRAN RRC connection may be established), (3) have “roved in” to GAN mode, or (4) have recently “roved out” of GAN mode (e.g., due to handover from GAN). 
     D. GA-CSR (Generic Access Circuit Switched Resources) 
     The GA-CSR protocol provides a circuit switched services resource management layer which supports the following functions: (1) setup of transport channels for CS traffic between the UE and GANC, (2) CS handover support between UTRAN/GERAN and GAN, (3) direct transfer of NAS messages between the UE and the core network, and (4) other functions such as CS paging and security configuration. 
     1. States of the GA-CSR Sub-Layer 
     The GA-CSR sub-layer in the UE can be in two states, GA-CSR-IDLE or GA-CSR-CONNECTED as illustrated in  FIG. 21 . The UE enters the GA-CSR-IDLE state  2115  when the UE switches the serving RR entity to GAN. This switch may occur only when the GA-RC is in the GA-RC-REGISTERED state  2110 . 
     The UE moves from the GA-CSR-IDLE state  2115  to the GA-CSR-CONNECTED state  2125  when the GA-CSR connection is established and returns to GA-CSR-IDLE state  2115  when the GA-CSR connection is released. Upon GA-CSR connection release, an indication that no dedicated CS resources exist is passed to the upper layers. The UE may also enter the GA-CSR-CONNECTED state  2125  while in the GA-RC-REGISTERED state  2110  in GERAN/UTRAN mode when Handover to GAN is being performed. In the same way, the UE enters the GA-RC-REGISTERED state  2110  in GERAN/UTRAN mode from the GA-CSR-CONNECTED state  2125  when Handover from GAN is successfully executed. 
     E. GA-PSR (Generic Access Packet Switched Resources) 
     The GA-PSR protocol provides a packet switched services resource management layer which supports the following functions: (1) setup of transport channels for PS traffic between the UE and network, (2) PS relocation/handover support between UTRAN/GERAN and GAN, (3) direct transfer of NAS messages between the UE and the PS core network, (4) transfer of GPRS user plane data, and (5) other functions such as PS paging and security configuration. 
     1. States of the GA-PSR Sub-Layer 
     The GA-PSR sub-layer in the UE can be in two states, GA-PSR-IDLE or GA-PSR-CONNECTED as illustrated in  FIG. 21 . The UE enters the GA-PSR-IDLE state  2120  when the UE switches the serving RR entity to GAN. This switch may occur only when the GA-RC is in the GA-RC-REGISTERED state  2110 . The UE moves from the GA-PSR-IDLE state  2120  to the GA-PSR-CONNECTED state  2130  when the GA-PSR connection is established and returns to GA-PSR-IDLE state  2120  when the GA-PSR connection is released. Upon GA-PSR connection release, an indication that no dedicated resources exist is passed to the upper layers. 
     The UE may also enter the GA-PSR-CONNECTED state  2130  while in the GA-RC-REGISTERED state  2110  in GERAN/UTRAN mode when Handover to GAN is being performed. In the same way, the UE enters the GA-RC-REGISTERED state  2110  in GERAN/UTRAN mode from the GA-PSR-CONNECTED state  2130  when Handover from GAN is successfully executed. The GA-PSR Packet Transport Channel (GA-PSR PTC) provides the association between the UE and GANC for the transport of GPRS user data over the Up interface. It is described in PS NAS Signaling Procedures in sub-section V.P, below. 
     IV. Gan Security Mechanisms 
     GAN supports security mechanisms at different levels and interfaces as depicted in  FIG. 22 . The security mechanisms  2205  over the Up interface protect control plane and user plane traffic flows between the UE  2210  and the GANC  2215  from unauthorized use, data manipulation and eavesdropping; i.e., authentication, encryption and data integrity mechanisms are supported. 
     Network access security  2220  includes the mechanisms defined in “3G Security; Security Architecture”, 3GPP TS 33.102 standard. Mutual authentication of the subscriber and the core network (CN)  2225  occurs between the MSC/VLR or SGSN and the UE and is transparent to the GANC. However, there is a cryptographic binding between the UE-CN authentication and the UE-GANC authentication to prevent man-in-the-middle attacks. 
     Additional application level security mechanisms  2230  may be employed in the PS domain to secure the end-to-end communication between the UE  2210  and the application server  2235 . For example, in some embodiments the UE  2210  may run the HTTP protocol over an SSL session for secure web access. 
     All control plane and user plane traffic sent between the UE  2210  and the GANC  2215  over the Up interface is protected by an IPSec tunnel between the UE  2210  and GANC-SEGW, that provides mutual authentication (using USIM credentials), encryption and data integrity using the same mechanisms as specified in “3G security; Wireless Local Area Network (WLAN) interworking security”, 3GPP TS 33.234. 
     As described above (in relation to  FIGS. 9 ,  12 ,  15 , and  19 ), some embodiments utilize a Femtocell access point (FAP) to communicatively couple a user equipment UE to the GANC via a Generic IP Network. As shown in  FIG. 9 , the FAP architecture for the CS control plane has an IPSec layer  920 . Similarly the FAP architectures for the CS user plane, PS control plane, and PS user plane architectures also include IPSec (or IPSec ESP) layers ( 1220 ,  1520 , and  1920  respectively). As shown in  FIGS. 9 ,  12 ,  15 , and  19 , these IPSec layers are over the transport IP layer and Remote IP layers of the GANC and are communicatively coupled to their corresponding GANC IPSec layers, thereby providing a secured link between the GANC and the FAP. 
     V. High-Level Procedures 
     A. Mode Selection in Multi-Mode Terminals 
     A Generic Access capable UE can support any IP access technology in addition to the UTRAN and possibly GERAN radio interfaces. The UE can be either in the GERAN/UTRAN mode or in GAN mode of operation. The UE can be configured to operate in one of the two modes (i.e., GERAN/UTRAN or GAN) at any given time. There may be a preferred mode of operation that can be configured by the subscriber or by the service provider through various mechanisms, e.g. device management. 
     On power up, the UE always starts in GERAN/UTRAN mode and executes the normal power-up sequence. The UE in some embodiments executes the power-up sequence as specified in “Non-Access-Stratum functions related to Mobile Station (MS) in idle mode”, 3GPP TS 23.122 standard. Following this, the UE may switch into GAN mode based on mode selection preference determined by user preferences or operator configuration. 
     The various preferences for the UE that are possible are as follows: GERAN/UTRAN-only, GERAN/UTRAN-preferred, GAN-preferred, and GAN-only. In GERAN/UTRAN-only, the UE RR entity remains in GERAN/UTRAN mode and does not switch to GAN mode. In GERAN/UTRAN-preferred, the UE RR entity is in GERAN/UTRAN mode as long as there is a PLMN available and not forbidden through GERAN/UTRAN. If no allowable PLMN is available through GERAN/UTRAN, and UE has successfully registered with a GAN over the generic IP access network, then the UE switches to GAN mode. When a PLMN becomes available over GERAN/UTRAN and the PLMN is not forbidden, or the UE has de-registered or lost connectivity with the GAN over the generic IP access network, the UE returns to GERAN/UTRAN mode. 
     In GAN-preferred, when the UE has successfully registered with the GAN over the generic IP access network, the UE switches to GAN mode and stays in this mode as long as the GAN is available. When the UE deregisters, or otherwise loses connectivity with the GAN over the generic IP access network, the UE switches to GERAN/UTRAN mode. 
     In GAN-only, the UE switches to GAN mode (after initial power up sequence in GERAN/UTRAN mode to obtain cellular network information, but excluding MM and GMM procedures with GERAN/UTRAN core network) and does not switch to GERAN/UTRAN mode. During the initial power up sequence in GERAN/UTRAN mode the UE shall ignore all paging messages received through the GERAN/UTRAN network. 
     B. PLMN Selection 
     In some embodiments, there are no changes from the PLMN selection procedures in the NAS layers (MM and above) in the UE, with the exception that in GAN mode the “in VPLMN background scan” is disabled. A GANC can only be connected to one PLMN. The PLMN selection in the NAS layers does not lead to a change of mode between GERAN/UTRAN mode and GAN mode. For a specific instance of PLMN selection, only PLMNs available via GAN or only PLMNs available via GERAN/UTRAN are provided to the NAS layer (i.e., no combination of the PLMNs available via GERAN/UTRAN and GAN). 
     In the case of a GAN capable UE, some embodiments require a GANC selection process as part of the process of establishing the connectivity between the UE and the GANC. This takes place when, during GAN registration, a GAN capable UE may have a choice among two or more GANC-PLMN pairs indicated by the Default GANC (i.e., in the GA-RC REGISTER REDIRECT message). The GANC selection process takes place while the UE is still in GERAN/UTRAN mode, and before the UE roves into GAN mode. If the current selected PLMN is available via GAN, it shall be selected. If not, the selection of GANC is implementation specific. 
     If the UE does not have any stored information related to the Serving GANC for the cell or AP to which the UE is currently connected, the UE attempts to register with the Default GANC (always located in the HPLMN) stored in UE. The UE includes an indication, identifying the GANC as the Default GANC in the GA-RC REGISTER REQUEST message. 
     When a UE attempts to register on the Default GANC including an indication that it is in automatic PLMN selection mode one of the followings happens. If the Default GANC decides to serve the UE, the Default GANC responds with a GA-RC REGISTER ACCEPT message. When the Default GANC decides to redirect the UE to another GANC within the HPLMN, the Default GANC responds with a GA-RC REGISTER REDIRECT message, not including a list of PLMN identities. 
     When the Default GANC decides to redirect the UE to a PLMN that is not the HPLMN, the Default GANC responds with a GA-RC REGISTER REDIRECT message and includes a list of PLMNs that may provide GAN service to the UE in its current location. The list contains one or more PLMN identities along with the identities of their associated GANC and SEGW nodes (either in IP address or FQDN format). Following the GANC selection process, the GA-RC entity in the UE attempts to register on the associated GANC. 
     If at any time the user wishes to perform manual PLMN selection or a “User reselection” irrespective of whether the UE is in manual or automatic PLMN selection mode, the UE sends a GA-RC REGISTER REQUEST message to the Default GANC, including an indication that it is in manual PLMN selection mode. The Default GANC is not allowed to accept the registration and responds with a GA-RC REGISTER REDIRECT message and includes a list of PLMNs that may provide GAN service to the UE in its current location. 
     When the UE includes the identity of the current serving GSM network in the GA-RC REGISTER REQUEST message, the Default GANC uses this to identify the list of PLMNs to send to the UE in the response message. 
     After successful registration with a serving GANC, the UE does not store the PLMN list. The UE does not use the PLMN list, provided to the UE during the registration procedure, for background scanning. A UE cannot use GA in a VPLMN unless the HPLMN supports and authorizes GA. 
     C. Re-selection between GERAN/UTRAN and GAN Modes 
     1. Rove-in (from GERAN/UTRAN Mode to GAN Mode) 
     This procedure is applicable only when GAN service is available, a UE is not in NC2 mode (applicable if the UE is in GERAN mode and as defined in “Radio subsystem link control”, 3GPP TS 45.008 standard) and has a UE preference for GAN-only, GAN-preferred or, if no allowable PLMN is available through GERAN/UTRAN, for GERAN/UTRAN-preferred. 
     Following successful GAN registration, the access mode in the UE is switched to GAN mode. The GA-CSR entity in the UE provides the NAS-related system information received in the GAN Registration Procedure to the NAS layers. The NAS considers the GANC-allocated cell identity as the current serving cell. 
     While in GAN mode, GERAN-RR and UTRAN RRC entities are detached from the RR-SAP in the UE. As a result the entities do not: (1) inform NAS about any GERAN/UTRAN cell re-selection and/or the change of system information of the current camping cell, (2) inform NAS about any newly found PLMN over GERAN or UTRAN, and (3) act on any paging request message received over GERAN or UTRAN. 
     2. Rove-out (from GAN Mode to GERAN/UTRAN Mode) 
     This procedure is applicable when the UE detaches from the generic IP access network, and its mode selection is GAN-preferred or GERAN/UTRAN-preferred. When the UE detaches from the generic IP access network, depending on prevailing circumstances the UE may be able to deregister first with the GANC. 
     For the GAN-preferred and GERAN/UTRAN-preferred mode selections, the UE detaches the GA-CSR entity from the RR-SAP and re-attaches the GERAN-RR or UTRAN RRC entity to the RR-SAP and restores normal GERAN-RR or UTRAN RRC functionality. For the GAN-only mode selection, GA-CSR remains attached to the NAS and the UE stays in GAN mode (i.e., in “No Service” condition). 
     D. GAN Registration Related Procedures 
     1. Discovery and Registration for Generic Access 
     The Discovery and Registration procedures are applicable only if the UE preference is operating in GAN-only, GAN-preferred or, if no allowable PLMN is available through GERAN/UTRAN, in GERAN/UTRAN-preferred mode. 
     Once the UE has established a connection to the generic IP access network, the UE determines the appropriate GANC-SEGW to connect to, by completing the Discovery Procedure to the Provisioning GANC in the HPLMN of the UE. The Provisioning GANC provides the address of the Default GANC in the HPLMN of the UE, to which the UE can register. 
     The UE attempts to register on the Default GANC provided by the Provisioning GANC during the Discovery procedure, by completing the Registration Procedure. The Default GANC may accept the Registration; redirect the UE to another GANC; or reject the Registration. 
     a) Security Gateway Identification 
     The USIM of the UE contains the FQDN (or IP address) of the Provisioning GANC and the associated SEGW or the UE derives this information based on information in the USIM. When the UE does not have any information about other GANCs and associated SEGW stored, then the UE completes the Discovery procedure towards the Provisioning GANC. As part of the Registration Procedure, the Default GANC can indicate whether this GANC and SEGW address or the address of a GANC that the UE is being redirected to, may be stored by the UE. 
     The UE can also store Serving GANC information for Serving GANCs with which the UE was able to complete a successful registration procedure. The default GANC is in control of whether the UE is allowed to store Serving GANC information. When there is no GERAN/UTRAN coverage in the AP location, the stored Serving GANC information is associated with the AP-ID. When there is GERAN/UTRAN coverage in the AP location, the stored Serving GANC information is associated with the GSM CGI or LAI or UTRAN CI. The stored Serving GANC information is: (1) serving SEGW FQDN or IP address following successful registration, (2) serving GANC FQDN or IP address following successful registration, and (3) optionally, Serving GANC TCP port following successful registration and if returned from the network. Different embodiments store different number of such entries in the UE is implementation specific. Only the last successfully registered GANC association is stored when the Default GANC indicates that the UE is allowed to store these addresses. A UE may preferentially join a generic IP access network point of attachment whose association with a Serving GANC has been stored in memory. 
     On connecting to the generic IP access network, when the UE has a stored Serving GANC for the AP-ID or the GERAN/UTRAN cell, the UE attempts to register with the associated Serving GANC in its memory. The GANC may still reject the UE for any reason even though it may have served the UE before. The UE deletes from its stored list the address of the Serving GANC on receiving a registration reject or if the registration fails for any other reason (e.g., not receiving any response). 
     If the UE does not receive a response to the Registration Request sent to the Serving GANC (and which is not the Default GANC), the UE re-attempt to register with the Default GANC. If the UE does not receive a response to the registration request sent to the Default GANC, it attempts the discovery procedure with the Provisioning GANC to obtain a new Default GANC. 
     In the case when a UE is attempting to register or discover a GANC after failing to register on a GANC, the UE provides in the Registration or Discovery procedure an indication that the UE has attempted to register on another GANC, the failure reason, and the GANC and SEGW addresses of the failed registration. When the UE connects to a generic IP access network, for which the UE does not have a stored Serving GANC in it&#39;s memory, the UE attempt to register with the Default GANC. 
     b) GANC Capabilities 
     GANC specific information is transferred to the UE on successful registration. 
     c) UE Capabilities 
     GAN specific capabilities of the UE are transferred to the GANC during registration. 
     d) Required GAN Services 
     The UE may request which GAN services it requires from the GANC as part of the Registration procedures. 
     e) GAN Mode Selection 
     The UE (i.e., with Iu-mode GAN support) transfers its GAN Mode Support information to the GANC during Discovery and Registration procedures; i.e., in the GAN Classmark IE. GAN Mode Support options are A/Gb mode supported, Iu mode supported, or both modes supported. When no GAN Mode Support information is received, the GANC assumes that the UE supports A/Gb mode operation only. 
     The provisioning GANC may use the received GAN Mode Support information to assign the UE to an appropriate default GANC (e.g., if separate A/Gb mode and Iu-mode GANCs are deployed in the network) or to an appropriate TCP port on the default GANC (e.g., if separate TCP ports are used for A/Gb mode and Iu-mode GAN service). The Iu-mode capable GANC also indicates the GAN mode to use for the current session in the GAN Mode Indicator IE; this allows the UE to determine the Iu-mode capability of the Home PLMN. 
     Table 1 enumerates the discovery handling for the various combinations of UE and Home PLMN GAN mode capabilities. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 GAN Mode Selection procedures associated with GAN Discovery 
               
            
           
           
               
               
            
               
                 UE GAN Mode 
                 Home PLMN GAN Mode Capabilities 
               
            
           
           
               
               
               
               
            
               
                 Capabilities 
                 A/Gb only 
                 Iu only 
                 Both 
               
               
                   
               
               
                 A/Gb only 
                 GANC: Handle as 
                 GANC: No GAN 
                 GANC: No GAN 
               
               
                   
                 normal A/Gb mode 
                 Mode Support 
                 Mode Support 
               
               
                   
                 discovery 
                 information provided 
                 information provided 
               
               
                   
                 UE: Proceed with 
                 or A/Gb mode (only) 
                 or A/Gb mode (only) 
               
               
                   
                 A/Gb mode 
                 indicated by UE, 
                 indicated by UE, 
               
               
                   
                 registration 
                 therefore Reject 
                 therefore handle as 
               
               
                   
                   
                 (Unspecified) 
                 normal A/Gb mode 
               
               
                   
                   
                 UE: Retry on next 
                 discovery. Assign UE 
               
               
                   
                   
                 power-on 
                 to A/Gb-capable 
               
               
                   
                   
                   
                 GANC. 
               
               
                   
                   
                   
                 UE: Proceed with 
               
               
                   
                   
                   
                 A/Gb mode 
               
               
                   
                   
                   
                 registration 
               
               
                 Iu only 
                 GANC: Handle as 
                 GANC: Iu Mode 
                 GANC: Iu Mode 
               
               
                   
                 normal A/Gb mode 
                 Support (only) 
                 Support (only) 
               
               
                   
                 discovery 
                 indicated by UE, 
                 indicated by UE, 
               
               
                   
                 UE: No GAN Mode 
                 therefore accept and 
                 therefore accept and 
               
               
                   
                 Selection provided by 
                 send GAN Mode 
                 send GAN Mode 
               
               
                   
                 GANC, therefore abort 
                 Indicator = Iu 
                 Indicator = Iu. Assign 
               
               
                   
                 GAN operation and 
                 UE: Proceed with Iu 
                 UE to Iu-capable 
               
               
                   
                 retry on next power-on 
                 mode registration 
                 GANC. 
               
               
                   
                   
                   
                 UE: Proceed with Iu 
               
               
                   
                   
                   
                 mode registration 
               
               
                 Both 
                 GANC: Handle as 
                 GANC: Support for 
                 GANC: Support for 
               
               
                   
                 normal A/Gb 
                 both modes indicated 
                 both modes indicated 
               
               
                   
                 discovery 
                 by UE, therefore 
                 by UE, therefore 
               
               
                   
                 UE: No GAN Mode 
                 accept and send GAN 
                 accept and send GAN 
               
               
                   
                 Selection provided by 
                 Mode Indicator = Iu 
                 Mode Indicator = Iu. 
               
               
                   
                 GANC, therefore 
                 UE: Proceed with Iu 
                 Assign UE to Iu- 
               
               
                   
                 proceed with Iu mode 
                 mode registration 
                 capable GANC. 
               
               
                   
                 registration (Note 1) 
                   
                 UE: Proceed with Iu 
               
               
                   
                   
                   
                 mode registration 
               
               
                   
               
               
                 Note: 
               
               
                 As described in Table 2 below, the result of Iu mode registration of a A/Gb-capable UE on a A/Gb-capable GANC is that the UE is placed in A/Gb mode. 
               
            
           
         
       
     
     In some embodiments, the default or serving GANC uses the received GAN Mode Support information to redirect the UE to a different GANC or a different TCP port on the current GANC. The Iu-mode capable GANC also indicates the GAN mode to use for the current session in the GAN Mode Indicator IE. 
     Table 2 enumerates the registration handling for the various combinations of UE and Home PLMN GAN mode capabilities. 
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 GAN Mode Selection procedures associated with GAN Registration 
               
            
           
           
               
               
            
               
                 UE GAN Mode 
                 Default/Serving GANC GAN Mode Capabilities 
               
            
           
           
               
               
               
               
            
               
                 Capabilities 
                 A/Gb only 
                 Iu only 
                 Both 
               
               
                   
               
               
                 A/Gb only 
                 GANC: Handle as 
                 GANC: No GAN 
                 GANC: No GAN 
               
               
                   
                 normal A/Gb mode 
                 Mode Support 
                 Mode Support 
               
               
                   
                 registration 
                 information provided 
                 information provided 
               
               
                   
                 UE: Proceed per A/Gb 
                 or A/Gb mode (only) 
                 or A/Gb mode (only) 
               
               
                   
                 mode GAN procedures 
                 indicated by UE, 
                 indicated by UE, 
               
               
                   
                   
                 therefore Reject 
                 therefore handle as 
               
               
                   
                   
                 (Invalid GANC) 
                 normal A/Gb mode 
               
               
                   
                   
                 UE: Attempt 
                 registration. If 
               
               
                   
                   
                 registration with 
                 required, redirect UE 
               
               
                   
                   
                 Default GANC or re- 
                 to A/Gb-capable 
               
               
                   
                   
                 discovery (per A/Gb 
                 GANC. 
               
               
                   
                   
                 mode GAN 
                 UE: Proceed per A/Gb 
               
               
                   
                   
                 procedures) 
                 mode GAN procedures 
               
               
                 Iu only 
                 GANC: Handle as 
                 GANC: Iu Mode 
                 GANC: Iu Mode 
               
               
                   
                 normal A/Gb mode 
                 Support (only) 
                 Support (only) 
               
               
                   
                 registration 
                 indicated by UE, 
                 indicated by UE, 
               
               
                   
                 UE: No GAN Mode 
                 therefore accept and 
                 therefore accept and 
               
               
                   
                 Selection provided by 
                 send GAN Mode 
                 send GAN Mode 
               
               
                   
                 GANC, therefore 
                 Indicator = Iu 
                 Indicator = Iu. 
               
               
                   
                 Deregister and treat as 
                 UE: Proceed per Iu 
                 UE: Proceed per Iu 
               
               
                   
                 register reject (Invalid 
                 mode GAN procedures 
                 mode GAN procedures 
               
               
                   
                 GANC) 
               
               
                 Both 
                 GANC: Handle as 
                 GANC: Support for 
                 GANC: Support for 
               
               
                   
                 normal A/Gb 
                 both modes indicated 
                 both modes indicated 
               
               
                   
                 registration 
                 by UE, therefore 
                 by UE, therefore 
               
               
                   
                 UE: No GAN Mode 
                 accept and send GAN 
                 accept and send GAN 
               
               
                   
                 Selection provided by 
                 Mode Indicator = Iu 
                 Mode Indicator = Iu or 
               
               
                   
                 GANC, therefore 
                 UE: Proceed per Iu 
                 A/Gb (see Note 1 
               
               
                   
                 proceed per A/Gb 
                 mode GAN procedures 
                 below). If required, 
               
               
                   
                 mode GAN procedures 
                   
                 redirect UE to Iu or 
               
               
                   
                   
                   
                 A/Gb-capable GANC. 
               
               
                   
                   
                   
                 UE: Proceed per Iu or 
               
               
                   
                   
                   
                 A/Gb mode GAN 
               
               
                   
                   
                   
                 procedures 
               
               
                   
               
               
                 Note 1: 
               
               
                 The GANC&#39;s choice of Iu-mode versus A/Gb-mode may be based on other information received in the GAN registration message from the UE, information stored in the GANC, and on operator (i.e., service provider) policy; e.g., if the GSM RR/UTRAN RRC State IE indicates that the UE is in GERAN Dedicated mode, the UE location is an area without UTRAN coverage and the operator wants to minimize inter-RAT handovers, the GANC may direct the UE to use A/Gb mode. 
               
            
           
         
       
     
     f) Discovery Procedure 
     When a UE supporting GAN first attempts to connect to a GAN, the UE needs to identify the Default GANC. Each GAN capable UE can be configured with the FQDN (or IP address) of the Provisioning GANC and the associated SEGW or the UE can derive this FQDN based on information in the USIM (see “Numbering, addressing and identification”, 3GPP TS 23.003 standard). The UE first connects to a Provisioning GANC-SEGW and GANC in the HPLMN of the UE, by establishing a secure IPSec tunnel and a TCP connection using the provisioned or derived addresses. The UE obtains the FQDN or IP address of the Default GANC in the HPLMN and the associated SEGW, through the Discovery procedure. 
     If no GERAN/UTRAN coverage is available when a UE connects to the GANC for GAN service, then the GANC cannot necessarily determine the location of the UE for the purposes of assigning the UE to the correct serving GANC (e.g., to enable handover and location-based services). The GANC permits the operator to determine the service policy in this case; e.g., the operator could provide service to the user with certain limitations (possibly with a user interface indication on the UE). When the UE initiates the Discovery/Registration procedures and no GERAN/UTRAN coverage is available, the GANC may have insufficient information to correctly route subsequent emergency calls. 
       FIG. 23  illustrates the Discovery procedure in some embodiments. The figure shows different messages exchanges between the UE  2305 , DNS  2310 , the provisioning GANC  2315 , the security gateway SEGW  2320  associated with the provisioning GANC  2315 , and the DNS server  2325  associated with the provisioning GANC  2315 . In the description below it is assumed that the UE  2305  has a mode selection of GAN-only or GAN-preferred or GERAN/UTRAN-preferred and that the UE has already connected to the generic IP access network. Different embodiments deem different signal levels as sufficient for triggering the GAN Discovery and Registration procedures. The following steps are taken during Discovery procedure in some embodiments. 
     As shown in  FIG. 23 , when the UE  2305  has a provisioned or derived FQDN of the Provisioning SEGW, the UE performs (in Step 1) a DNS query (via the generic IP access network interface) to resolve the FQDN to an IP address. When the UE has a provisioned IP address for the Provisioning SEGW, the DNS step is omitted. Next, the DNS Server  2310  returns (in Step 2) a response including the IP Address of the Provisioning SEGW  2320 . 
     As shown, the UE  2305  establishes (in Step 3) a secure tunnel to the Provisioning SEGW  2320 . When the UE  2305  has a provisioned or derived FQDN of the Provisioning GANC  2315 , the UE  2305  performs (in Step 4) a DNS query (via the secure tunnel) to the DNS server  2325  associated with the provisioning GANC  2315  to resolve the FQDN to an IP address. When the UE  2305  has a provisioned IP address for the Provisioning GANC, the DNS step will be omitted. The DNS Server  2325  returns (in Step 5) a response including the IP Address of the Provisioning GANC  2315 . 
     The UE  2305  sets up a TCP connection to a well-defined port on the Provisioning GANC  2315 . It then queries (in Step 6) the Provisioning GANC  2315  for the Default GANC, using GA-RC DISCOVERY REQUEST. The message contains: (1) Cell Info: Either current camping UTRAN/GERAN cell ID or the last LAI where the UE successfully registered, along with an indicator stating which one it is, (2) Generic IP access network attachment point information: AP-ID, as defined in Identifiers in GAN, sub-section VII, below, (3) UE Identity: IMSI, and (4) GAN Classmark: Including indications of A/Gb Mode supported and Iu Mode supported. 
     Next, the Provisioning GANC  2315  returns (in Step 7) the GA-RC DISCOVERY ACCEPT message, using the information provided by the UE (e.g. the cell ID), to provide the FQDN or IP address of the Default GANC and its associated Default SEGW. This is done so the UE is directed to a “local” Default GANC in the HPLMN to optimize network performance. The GANC Port that the UE must use for registration may be included. The GAN Mode Indicator may be included as described in GAN Mode Section, sub-section above. 
     When the Provisioning GANC  2315  cannot accept the GA-RC DISCOVERY REQUEST message, it returns (in Step 8) a GA-RC DISCOVERY REJECT message indicating the reject cause. The secure IPSec tunnel to the Provisioning SEGW  2320  is released (in Step 9). It is possible to reuse the same IPSec tunnel for GAN Registration procedures. In this case the IPSec tunnel is not released. 
     g) Registration Procedure—Normal Case 
     Following the Discovery procedure the UE establishes a secure tunnel with the security gateway of the Default GANC, provided by the Provisioning GANC in the Discovery procedure, and attempts to register with the Default GANC. The Default GANC may become the Serving GANC for that connection by accepting the registration, or the Default GANC may redirect a UE performing registration to a different Serving GANC. 
     GANC redirection may be based on information provided by the UE during the Registration procedure, operator chosen policy or network load balancing. The GAN Registration procedure serves the following functions: (1) Ensures the UE is registered to the appropriate GANC entity; i.e., with use of the redirection process, (2) Informs the GANC that the UE is now connected through a generic IP access network and is available at a particular IP address. The GANC maintains the registration context for the purposes of (for example) mobile-terminated calling, (3) Provides the UE with the operating parameters associated with the GAN service. The “System Information” message content that is applicable to the GAN cell is delivered to the UE during the GAN registration process. This enables the UE to switch to GAN mode, and following the Registration procedure trigger NAS procedures with the core network (such as Location/Routing Area Update, mobile originated calls, mobile terminated calls, etc.), and (4) Enables the UE to request which GAN services are required. 
       FIG. 24  illustrates Registration procedure in some embodiments. The figure shows different messages exchanges between the UE  2405 , DNS  2410 , the provisioning GANC  2415 , the security gateway SEGW  2420  associated with the provisioning GANC  2415 , and the DNS server  2425  associated with the provisioning GANC  2415 . The following steps are done during Registration procedure. 
     As shown in  FIG. 24 , when the UE  2405  was provided the FQDN of the Default or Serving SEGW, the UE performs (in Step 1) a DNS query (via the generic IP access network interface) to resolve the FQDN to an IP address. When the UE has a provisioned IP address for the SEGW, the DNS step is omitted. The DNS Server  2410  returns (in Step 2) a response. 
     As shown, the UE  2405  sets up (in Step 3) a secure IPSec tunnel to the SEGW  2420 . This step may be omitted if an IPSec tunnel is being reused from an earlier Discovery or Registration. When the UE  2405  was provided the FQDN of the Default or Serving GANC, the UE then performs (in Step 4) a DNS query (via the secure tunnel) to resolve the FQDN to an IP address. When the UE has an IP address for the GANC, the DNS step is omitted. Next, the DNS Server  2425  returns (in Step 5) a response. 
     The UE  2405  then sets up a TCP connection to a TCP port on the GANC. The TCP port can either be a well-known port or one that has been earlier received from the network during Discovery or Registration. The UE  2405  attempts (in Step 6) to register on the GANC by transmitting the GA-RC REGISTER REQUEST. The message includes: (1) Cell Info: Either current camping UTRAN/GERAN cell ID, or last LAI where the UE successfully registered, along with an indicator stating which one it is, (2) Generic IP access network attachment point information: AP-ID, as defined in Identifier in GAN, Section VII, below, (3) UE Identity: IMSI, (4) UE Capability Information, (5) GAN Services Required, (6) GAN Classmark: Including indications of A/Gb Mode supported, Iu Mode supported. 
     When the GANC  2415  accepts the registration attempt, the GANC  2415  responds (in Step 7) with a GA-RC REGISTER ACCEPT. In this case the TCP connection and the secure IPSec tunnel are not released and are maintained as long as the UE is registered to this GANC. 
     The GA-RC REGISTER ACCEPT message includes (1) GAN Capability Information and (2) GAN specific system information which includes (a) GAN Mode Indicator: A/Gb Mode GAN or Iu Mode GAN, (b) Cell description of the GAN cell, (c) Location-area identification comprising the mobile country code, mobile network code, and location area code corresponding to the GAN cell, (d) Cell identity identifying the cell within the location area corresponding to the GAN cell, and (e) Applicable system timer values (e.g., for the application-level keep alive message transmission interval, see Keep Alive sub-section, below) 
     Alternatively, the GANC  2415  may reject the request. In this case, the GANC  2415  responds (in Step 8) with a GA-RC REGISTER REJECT indicating the reject cause. The TCP connection and the secure IPSec tunnel are then released. 
     Alternatively, if the GANC  2415  decides to redirect the UE to (another) Serving GANC, the GANC  2415  responds (in Step 9) with a GA-RC REGISTER REDIRECT providing the FQDN or IP address of the target Serving GANC and the associated SEGW, and the GAN Mode Indicator if the GANC requires that a particular mode be used with the Serving GANC (e.g., if the GANC knows that the Serving GANC supports only A/Gb mode GAN). In this case the TCP connection is released and the secure IPSec tunnel is optionally released (in Step 10) depending on if the network indicates that the same IPSec tunnel can be reused for the next registration. The GA-RC REGISTER REDIRECT message may contain: (1) a single Serving SEGW and GANC address or (2) a list of PLMN identities and associated Serving SEGW and GANC addresses. The message also may contain an Indication of whether GANC address(es) can be stored in the UE for future use. 
     a) Registration Procedure—Abnormal Cases 
     When the Serving GANC rejects the Register request and does not provide redirection to another Serving GANC, the UE re-attempts Registration to the Default GANC including a cause that indicates the failed registration attempt and the Serving GANC and SEGW with which the Register request failed. The UE also deletes all stored information about this Serving GANC. 
     When the Default GANC rejects a Registration Request and is unable to provide redirection to suitable Serving GANC, the UE may re-attempt the Discovery procedure to the Provisioning GANC (including a cause indicating the failed registration attempt and the Default GANC provided in the last Discovery procedure). The UE also deletes all stored information about the Default GANC. 
     2. De-Registration 
       FIG. 25  illustrates De-Registration initiated by the UE  2505  in some embodiments. The GA-RC De-Registration procedure allows the UE  2505  to explicitly inform the GANC  2510  that it is leaving GAN mode (e.g., when it detaches from the generic IP access network), by sending (in Step 1) a GA-RC DEREGISTER message to the GANC  2510 , allowing the GANC  2510  to free resources that it assigned to the UE  2505 . The GANC  2510  also supports “implicit GAN de-registration”, when the TCP connection to the UE is abruptly lost. 
       FIG. 26  illustrates De-Registration initiated by the GANC  2610  in some embodiments. As shown, the GANC  2610  can autonomously release the UE registration context, and send (in Step 1) a GA-RC DEREGISTER message to the UE  2605 . Alternatively, the GANC  2610  can implicitly deregister the UE  2605  by closing the TCP connection with the UE. At power-down the GA-RC sublayer of the UE ensures that the UE explicitly detaches from the network, where possible, before completing the GA-RC De-Registration procedure. 
     3. Registration Update 
       FIG. 27  illustrates Registration Update in some embodiments. The GA-RC Registration Update procedure allows the UE  2705  to update information in the GANC  2710  regarding changes to the identity of the overlapping GERAN cell or changes to the generic IP access network point of attachment. As shown, the UE  2705  sends (in Step 1) a GA-RC REGISTER UPDATE UPLINK message to the GANC  2710  carrying the updated information. This may result in the UE  2705  being redirected to another serving GANC, or being denied service; e.g., due to operator policy. 
     When the UE  2705  detects UTRAN/GERAN coverage after reporting no coverage during GAN registration, the UE sends the GA-RC REGISTER UPDATE UPLINK to the GANC with the updated information. Whenever the generic IP access network point of attachment changes, the UE sends a GA-RC REGISTER UPDATE UPLINK to the GANC with the updated generic IP access network point of attachment information. When the UE requires to update the GANC with a new list of GAN Services required, then the UE sends GA-RC REGISTER UPDATE UPLINK message to the GANC including the new GAN Services Required list. 
     The GANC  2710  may optionally send (in Step 2) the GA-RC REGISTER REDIRECT when it decides to redirect the UE based on updated information. The GANC  2710  may also optionally deregister the UE  2705  on receiving an update by sending (in Step 3) GA-RC DEREGISTER to the UE. 
       FIG. 28  illustrates Registration Update Downlink procedure in some embodiments. The GAN Registration Update procedure also allows the GANC  2810  to update the GAN system information in the UE  2805 , if needed, by sending (in Step 1) a GA-RC REGISTER UPDATE DOWNLINK message to the UE carrying the updated information. 
     4. Keep Alive 
       FIG. 29  illustrates the Keep Alive process in some embodiments. The Keep Alive process is a mechanism between the peer GA-RC entities to indicate that the UE is still registered to the GANC. Using periodic transmissions (in Step 1) of the GA-RC KEEP ALIVE message the UE  2805  in turn determines that the GANC  2810  is still available using the currently established lower layer connection. 
     5. Cell Broadcast Information 
       FIG. 30  illustrates the Cell Broadcast Information mechanism of some embodiments. The Cell Broadcast Information is a mechanism between the peer GA-RC entities, allowing the GANC to pass the UE information relating to the Cell Broadcast Services. The UE  3005  includes GAN Service Required information in the GA-RC REGISTER REQUEST and GA-RC REGISTER UPDATE UPLINK messages passed to the GANC, indicating that the UE requires the Cell Broadcast Service. The GANC  3010  then passes (in Step 1) the required information to the UE  1105  in the GA-RC CELL BROADCAST INFO message. 
     E. Authentication 
     The Up interface supports the ability to authenticate the UE with the GANC (for the purposes of establishing the secure tunnel) using GSM or UMTS credentials. Authentication between UE and GANC is performed using EAP-SIM or EAP-AKA within IKEv2. 
     F. Encryption and Integrity Protection 
     All control and user plane traffic over the Up interface is sent through the pair of IPSec ESP tunnel mode security associations (one for each direction) that are established during the establishment of the IKEv2 security association. Encryption and integrity protection are via the negotiated cryptographic algorithms, based on core network policy, enforced by the GANC-SEGW. 
     G. GA-CSR Connection handling 
     The Iu-mode GAN GA-CSR connection is a logical connection between the UE and the GANC for the CS domain. A GA-CSR connection is established when the upper layers in the UE request the establishment of a CS domain signaling connection and the UE is in GA-CSR-IDLE state; i.e., no GA-CSR connection exists. When a successful response is received from the network, GA-CSR replies to the upper layer that the CS domain signaling connection is established and the UE has entered the equivalent of the RRC connected mode (i.e., the GA-CSR-CONNECTED state). 
     1. GA-CSR Connection Establishment 
       FIG. 31  illustrates successful and unsuccessful establishment of the GA-CSR Connection in some embodiments. As shown, the UE  3105  initiates GA-CSR connection establishment by sending (in Step 1) the GA-CSR REQUEST message to the GANC  3110 . This message contains the Establishment Cause indicating the reason for GA-CSR connection establishment. 
     When GANC determines that the connection request can be accepted, the GANC  3110  signals the acceptance of the connection request to the UE  3105  by sending (in Step 2) the GA-CSR REQUEST ACCEPT and the UE enters the GA-CSR-CONNECTED state. On the other hand, when the GANC determines that the GA-CSR connection request has to be rejected, the GANC  3110  sends (in Step 3) a GA-CSR REQUEST REJECT to the UE  3105  indicating the reject cause, completing the procedure. 
     2. GA-CSR Connection Release 
       FIG. 32  illustrates release of the logical GA-CSR connection between the UE and the GANC in some embodiments. As shown, the MSC  3215  indicates to the GANC  3210  to release the CS resources allocated to the UE, by sending (in Step 1) the RANAP Iu Release Command message to the GANC  3210 . 
     Next, the GANC  3210  confirms (in Step 2) resource release to MSC  3215  using the Iu Release Complete message. The GANC  3210  then commands (in Step 3) the UE  3205  to release resources, using the GA-CSR RELEASE message. Finally, the UE  3205  confirms (in Step 4) resource release to the GANC using the GA-CSR RELEASE COMPLETE message and the GA-CSR state in the UE changes to GA-CSR-IDLE. 
     H. CS Security Mode Control 
       FIG. 33  illustrates the message flow for security mode control in some embodiments. As shown, the MSC  3315  sends (in Step 1) the RANAP Security Mode Command message to GANC  3310 . This message contains the integrity key (IK) and allowed algorithms, and optionally the encryption key (CK) and allowed algorithms. 
     Next, the GANC  3310  sends (in Step 2) the GA-CSR SECURITY MODE COMMAND message to the UE  3305 . This message indicates the integrity protection and encryption settings (i.e., that are applicable after relocation to UTRAN), and a random number. The UE stores the information for possible future use after a relocation to UTRAN. 
     Next, the UE  3305  computes a MAC based on the random number, the UE IMSI and the integrity key calculated by the UE. The MAC or “message authentication code” allows the GANC to verify that the UE has been able to calculate the same integrity key value as the GANC received from the MSC, thereby preventing certain “man-in-the-middle” security attacks. The UE  3305  then sends (in Step 3) the GA-CSR SECURITY MODE COMPLETE message to the GANC  3310  to signal its selected algorithm and the computed MAC. 
     The GANC  3310  then verifies the MAC using the random number, the UE IMSI and the integrity key provided by the MSC in Step 1. When the GANC verifies the MAC to be correct (i.e., the GANC-calculated MAC is the same as the UE-calculated MAC) it sends (in Step 4) the Security Mode Complete message to the MSC  3315 . The MAC proves that the identity that is authenticated to the GANC is the same as the identity authenticated to the core network. 
     I. CS NAS Signaling Procedures 
     After GA-CSR connection establishment, NAS signaling may be transferred from MSC-to-UE and from UE-to-MSC. 
     1. MSC-to-UE NAS Signaling 
       FIG. 34  illustrates MSC-to-UE NAS signaling in some embodiments. As shown, for MSC-to-UE NAS signaling, the MSC  3415  sends (in Step 1) a NAS PDU to the GANC via the RANAP Direct Transfer message. The GANC  3410  encapsulates the NAS PDU within a GA-CSR DL DIRECT TRANSFER message and forwards (in Step 2) the message to the UE  3405  via the existing TCP connection. 
     2. UE-to-MSC NAS Signaling 
       FIG. 35  illustrates UE-to-MSC NAS signaling in some embodiments. As shown, the UE  3505  receives a request from the NAS layer to transfer an uplink NAS PDU. Assuming that the required signaling connection already exists, the UE  3505  encapsulates the NAS PDU within a GA-CSR UL DIRECT TRANSFER message and sends (in Step 1) the message to the GANC  3510 . The GANC  3510  relays (in Step 2) the received message to the MSC  3515  via the RANAP Direct Transfer message. 
     J. Mobile Originated CS Call 
     1. GANC Terminates Iu UP Protocol 
       FIG. 36  illustrates steps performed during a mobile originated CS call in some embodiments. The procedure assumes that the UE is in GAN mode; i.e., it has successfully registered with the GANC and GA-CSR is the serving RR entity for CS services in the UE. It also assumes that no GA-CSR signaling connection exists between the UE and GANC (i.e., GA-CSR-IDLE state). As shown, the GA-CSR Connection Establishment procedure is performed (in Step 1). In some embodiments, this procedure is performed as described in GA-CSR Connection Establishment sub-section, above. Next, the UE  3605  sends the CM Service Request message to the GANC  3610  within the GA-CSR UL DIRECT TRANSFER message. 
     Next, the GANC  3610  establishes an SCCP connection to the MSC  3615  and forwards (in Step 3) the NAS PDU (i.e., the CM Service Request message) to the MSC  3615  using the RANAP Initial UE Message. The message includes the Domain Indicator set to value ‘CS domain’. Subsequent NAS messages between the UE and MSC will be sent between GANC and MSC using the RANAP Direct Transfer message. 
     The MSC  3615  may optionally authenticate (in Step 4) the UE using standard UTRAN authentication procedures. The MSC  3615  may optionally initiate (in Step 5) the Security Mode Control procedure described in CS Security Mode Control sub-section, above. The UE  3605  sends (in Step 6) the Setup message providing details on the call to the MSC and its bearer capability and supported codecs. This message is contained within the GA-CSR UL DIRECT TRANSFER between the UE and the GANC. The GANC forwards the Setup message to the MSC. 
     Next, the MSC  3615  indicates (in Step 7) it has received the call setup and it will accept no additional call-establishment information using the Call Proceeding message to the GANC. The GANC forwards (in Step 7) this message to the UE in the GA-CSR DL DIRECT TRANSFER message. 
     The MSC  3615  requests (in Step 8) the GANC  3610  to assign call resources using the RANAP RAB Assignment Request message. The MSC  3615  includes the RAB-ID, the CN Transport Layer Address and the CN Iu Transport Association for user data, and an indication that Iu UP support mode is required, among other parameters. 
     The GANC  3610  then sends (in Step 9) the GA-CSR ACTIVATE CHANNEL message to the UE  3605  including bearer path setup information such as: (1) Channel mode, (2) 
     Multi-rate codec configuration, (3) UDP port &amp; the IP address for the uplink RTP stream, and (4) 
     Voice sample size. 
     Next, the UE  3605  sends (in Step 10) the GA-CSR ACTIVATE CHANNEL ACK to the GANC  3610  indicating the UDP port for the downlink RTP stream. Since Iu UP support mode is indicated by the MSC in step 8, the GANC  3610  sends (in Step 11) the Iu UP INITIALIZATION packet to the MSC. 
     In response, the MSC responds (in Step 12) with the Iu UP INITIALISATION ACK packet. The GANC  3610  signals (in Step 13) the completion of the RAB establishment to the UE  3605  with the GA-CSR ACTIVATE CHANNEL COMPLETE message. Alternatively, Steps 11 and 12 may occur before Step 9. 
     The GANC  3610  signals to the MSC  3615  that the RAB has been established by sending (in Step 14) a RANAP RAB Assignment Response message. The MSC  3615  signals to the UE  3505 , with the Alerting message, that the called party is ringing. The message is transferred (in Step 15) to the GANC  3610  and GANC forwards (in Step 15) the message to the UE  3605  in the GA-CSR DL DIRECT TRANSFER. When the UE has not connected the audio path to the user, it generates ring back to the calling party. Otherwise, the network-generated ring back will be returned to the calling party. 
     Next, the MSC  3615  signals that the called party has answered, via the Connect message. The message is transferred (in Step 16) to the GANC  3610  and GANC forwards (in Step 16) the message to the UE in the GA-CSR DL DIRECT TRANSFER. The UE connects the user to the audio path. If the UE is generating ring back, it stops and connects the user to the audio path. 
     The UE  3605  then sends (in Step 17) the Connect Ack message in response, and the two parties are connected for the voice call. This message is contained within the GA-CSR UL DIRECT TRANSFER between the UE and the GANC. The GANC forwards the Connect Ack message to the MSC. At this time, bi-directional voice traffic flows (in Step 18) between the UE  3605  and MSC  3615  through the GANC  3610 . 
     2. UE Terminates Iu UP Protocol 
     Some embodiments utilize an alternative procedure for a mobile originated CS call.  FIG. 37  illustrates steps performed during a mobile originated CS call in these embodiments. The procedure assumes that the UE is in GAN mode; i.e., it has successfully registered with the GANC and GA-CSR is the serving RR entity for CS services in the UE. It also assumes that no GA-CSR signaling connection exists between the UE and GANC (i.e., GA-CSR-IDLE state). Steps 1 to 8 are performed the same as described for steps 1 to 8 shown in  FIG. 36  above and are not repeated for simplicity. 
     Since Iu UP support mode is indicated by the MSC in step 8 (as described in reference with  FIG. 36 ), the GANC indicates (in Step 9) that Iu UP support mode is required in the GA-CSR ACTIVATE CHANNEL message, and the UE  3705  sends (in Step 10) the Iu UP INITIALIZATION packet to the MSC  3715 . In response, the MSC  3715  responds (in Step 11) with the Iu UP INITIALISATION ACK packet. Next, the UE  3705  sends (in Step 12) the GA-CSR ACTIVATE CHANNEL ACK to the GANC  3710 . 
     The GANC  3710  signals to the MSC  3715  that the RAB has been established by sending (in Step 13) a RANAP RAB Assignment Response message. The GANC  3710  also sends (in Step 14) a GA-CSR ACTIVATE CHANNEL COMPLETE message to the UE  3705 . Steps 15 to 18 are performed the same as described for steps 15 to 18 shown in  FIG. 36  above and are not repeated for simplicity. 
     K. Mobile Terminated CS Call 
       FIG. 38  illustrates steps performed during a mobile terminated CS call in some embodiments. The description of the procedure assumes that the UE is in GAN mode; i.e., it has successfully registered with the GANC and GA-CSR is the serving RR entity for CS services in the UE. It also assumes that no GA-CSR signaling connection exists between the UE and GANC (i.e., the UE is in the GA-CSR-IDLE state). When a mobile-terminated call arrives at the MSC  3815 , as shown in  FIG. 38 , the MSC  3815  sends (in Step 1) a RANAP Paging message to the GANC  3810  identified through the last Location Update received by it and includes the TMSI if available. The IMSI of the mobile being paged is always included in the request. 
     Next, the GANC  3810  identifies the UE registration context using the IMSI provided by the MSC  3815 . It then pages (in Step 2) the UE  3805  using the GA-CSR PAGING REQUEST message. The message includes the TMSI, if available in the request from the MSC; else it includes only the IMSI of the UE. 
     The UE  3805  responds with a GA-CSR PAGING RESPONSE. The UE transitions to the GA-CSR CONNECTED state. The GANC  3810  establishes an SCCP connection to the MSC  3815 . The GANC  3810  then forwards (in Step 4) the paging response to the MSC  3815  using the RANAP Initial UE Message. Subsequent NAS messages between the UE and core network will be sent between GANC and MSC using the RANAP Direct Transfer message. 
     The MSC  3815  may optionally authenticate (in Step 5) the UE  3805  using standard UTRAN authentication procedures. The MSC may optionally update (in Step 6) the security configuration in the UE, via the GANC, as described in CS Security Mode Control sub-section above. 
     The MSC  3815  then initiates (in Step 7) call setup using the Setup message sent to the UE via GANC. GANC forwards (in Step 7) this message to the UE  3805  in the GA-CSR DL DIRECT TRANSFER message. 
     Next, the UE  3805  responds with Call Confirmed using the GA-CSR UL DIRECT TRANSFER after checking it&#39;s compatibility with the bearer service requested in the Setup and modifying the bearer service as needed. When the Setup included the signal information element, the UE alerts the user using the indicated signal, otherwise the UE alerts the user after the successful configuration of the user plane. The GANC  3810  forwards (in Step 8) the Call Confirmed message to the MSC  3815 . 
     Next, the MSC  3815  initiates the assignment procedure with the GANC  3810 , which triggers (in Step 9) the setup of the RTP stream (voice bearer channel) between the GANC and UE, same as steps 8-14 in the mobile originated CS call scenario described above. 
     The UE  3805  then signals (in Step 10) that it is alerting the user, via the Alerting message contained in the GA-CSR UL DIRECT TRANSFER. The GANC forwards (in Step 10) the Alerting message to the MSC. The MSC sends a corresponding alerting message to the calling party. 
     The UE  3805  then signals (in Step 11) that the called party has answered, via the Connect message contained in the GA-CSR UL DIRECT TRANSFER. The GANC  3810  forwards (in Step 11) the Connect message to the MSC  3815 . The MSC sends a corresponding Connect message to the calling party and through connects the audio. The UE connects the user to the audio path. 
     Next, the MSC  3815  acknowledges (in Step 12) via the Connect Ack message to the GANC  3810 . GANC forwards (in Step 12) this message to the UE  3805  in the GA-CSR DL DIRECT TRANSFER. The two parties on the call are connected on the audio path. At this time, bi-directional voice traffic flows (in Step 13) between the UE and MSC through the GANC. 
     L. CS Call Clearing 
       FIG. 39  illustrates call clearing initiated by the UE in some embodiments. As shown, the UE  3905  sends (in Step 1) the Disconnect message to the MSC  3915  to release the call. This message is contained in the GA-CSR UL DIRECT TRANSFER message between UE  3905  and GANC  3910 . The GANC  3910  forwards (in Step 1) the Disconnect message to the MSC (i.e., using the RANAP Direct Transfer message). 
     Next, the MSC  3915  responds (in Step 2) with a Release message to the GANC. The GANC forwards (in Step 2) this message to the UE  3905  using the GA-CSR DL DIRECT TRANSFER message. The UE  3905  responds (in Step 3) with the Release Complete message. This message is contained within the GA-CSR UL DIRECT TRANSFER message between UE and GANC. The GANC forwards (in Step 3) the Disconnect message to the MSC. The MSC triggers (in Step 4) the release of connection as described in GA-CSR connection release sub-section, above. 
     M. CS Handover 
     1. CS Handover from GERAN to GAN 
     a) GANC Terminates Iu UP Protocol 
       FIG. 40  illustrates CS handover from GERAN to GAN in some embodiments. The description of the GERAN to GAN handover procedure assumes the following: (1) the UE is on an active call on the GERAN, (2) the UE mode selection is GAN-preferred, or if GERAN/UTRAN-preferred, the RxLev from the current serving cell drops below a defined threshold. In some embodiments, this threshold can be specified as a fixed value, or provided by the GERAN BSS to the UE in dedicated mode, (3) the UE has successfully registered with a GANC, allowing the UE to obtain GAN system information, and (4) the GERAN provides information on neighboring 3G cells such that one of the cells in the 3G neighbor list matches the 3G cell information associated with the GANC, as provided in the AS-related component of the system information obtained from the GANC. As shown, the UE  4005  begins to include GAN cell information in the Measurement Report message to the GERAN BSC  4015 . The UE  4005  reports the highest signal level for the GAN cell. This is not the actual measured signal level on GAN, rather an artificial value (e.g., RxLev=63), allowing the UE to indicate preference for the GAN. 
     Based on UE measurement reports and other internal algorithms, the GERAN BSC  4015  decides to handover to the GAN cell. The BSC  4015  starts the handover preparation by sending (in Step 2) a Handover Required message to the MSC  4020 , identifying the target 3G RNC (GANC). 
     The MSC  4020  requests (in Step 3) the target GANC  4010  to allocate resources for the handover using the Relocation Request message. The UE is identified by the included IMSI parameter. 
     Since Iu UP support mode is indicated, the GANC  4010  sends (in Step 4) the Iu UP INITIALISATION packet to the MSC. The MSC responds (in Step 5) with the Iu UP INITIALISATION ACK packet. 
     The GANC  4010  builds a Handover to UTRAN Command message and sends it (in Step 6) to the MSC  4020  through the Relocation Request Acknowledge message. The MSC forwards (in Step 7) the Handover to UTRAN Command message to the GERAN BSC  4015  in the BSSMAP Handover Command message, completing the handover preparation. 
     Next, the GERAN BSC  4015  sends (in Step 8) the Intersystem to UTRAN Handover Command message, containing the Handover to UTRAN Command message, to the UE  4005  to initiate handover to GAN. The UE does not switch its audio path from GERAN to GAN until handover completion (i.e., until it sends the GA-CSR HANDOVER COMPLETE message) to keep the audio interruption short. 
     The UE  4005  accesses (in Step 9) the GANC  4010  using the GA-CSR HANDOVER ACCESS message, and provides the entire Intersystem to UTRAN Handover Command message received from GERAN. The GANC  4010  sends (in Step 10) the GA-CSR ACTIVATE CHANNEL message to the UE  4005  including bearer path setup information such as: (1) Channel mode, (2) Multi-rate codec configuration, (3) UDP port &amp; the IP address for the uplink RTP stream, and (4) Voice sample size. 
     Next, the UE  4005  sends (in Step 11) the GA-CSR ACTIVATE CHANNEL ACK to the GANC  4010  indicating the UDP port for the downlink RTP stream. The GANC  4010  signals (in Step 11) the completion of the RAB establishment to the UE  4005  with the GA-CSR ACTIVATE CHANNEL COMPLETE message. 
     The UE  4005  transmits (in Step 13) the GA-CSR HANDOVER COMPLETE message to indicate the completion of the handover procedure at its end. It switches the user from the GERAN user plane to the GAN user plane. The GANC  4010  indicates (in Step 14) to the MSC  4020  that it has detected the UE, using Relocation Detect message. The CN can optionally now switch the user plane from the source GERAN to the target GAN. 
     Bi-directional voice traffic is now (in Step 15) flowing between the UE  4005  and MSC  4020 , via GANC  4010 . The target GANC  4010  indicates (in Step 16) the handover is complete, using the Relocation Complete message. If it had not done so before, the CN now switches the user plane from source GERAN to target GAN. 
     The CN tears down (in Step 17) the connection to the source GERAN, using Clear Command message. Finally, the source GERAN  4015  confirms (in Step 18) the release of GERAN resources allocated for this call, using Clear Complete message. 
     b) UE Terminates Iu UP Protocol 
     Some embodiments utilize an alternative procedure for CS handover from GERAN to GAN.  FIG. 41  illustrates steps performed during GERAN to GAN in these embodiments. The description of the GERAN to GAN handover procedure assumes the following: (1) the UE is on an active call on the GERAN, (2) the UE mode selection is GAN-preferred, or if GERAN/UTRAN-preferred, the RxLev from the current serving cell drops below a defined threshold. In some embodiments, this threshold can be specified as a fixed value, or provided by the GERAN BSS to the UE in dedicated mode, (3) the UE has successfully registered with a GANC, allowing the UE to obtain GAN system information, and (4) the GERAN provides information on neighboring 3G cells such that one of the cells in the 3G neighbor list matches the 3G cell information associated with the GANC, as provided in the AS-related component of the system information obtained from the GANC. Steps 1 to 3 are performed the same as described for steps 1 to 3 shown in  FIG. 40  above and are not repeated for simplicity. 
     The GANC  4110  sends (in Step 4) the GA-CSR ACTIVATE CHANNEL message to the UE  4105  including bearer path setup information such as: (1) Channel mode, (2) Multi-rate codec configuration, (3) UDP port &amp; the IP address for the uplink RTP stream, (4) 
     Voice sample size, and an indication that Iu UP support mode is required. In some embodiments, the GANC  4110  includes the Radio Access Bearer (RAB) parameters, and the Iu UP parameters (e.g., Iu UP mode, where support mode is used for AMR voice calls). 
     Since Iu UP support mode is indicated, the UE  4110  sends (in Step 5) the Iu UP INITIALISATION packet to the IP address and UDP port indicated in the GA-CSR ACTIVATE CHANNEL message. 
     The MSC  4115  responds (in Step 6) with the Iu UP INITIALISATION ACK packet. The MSC  4115  sends the message to the source IP address and UDP port number of the received INITIALISATION packet. The UE  4105  sends (in Step 7) the GA-CSR ACTIVATE CHANNEL ACK to the GANC  4110 . The GANC  4110  builds a Handover to UTRAN Command message and sends (in Step 8) it to the CN  4115  through the Relocation Request Acknowledge message. 
     The GANC  4110  signals (in Step 9) the completion of the RAB establishment to the UE  4105  with the GA-CSR ACTIVATE CHANNEL COMPLETE message. An end-to-end audio path now exists between the UE  4105  and the MSC  4115 . The MSC  4115  forwards (in Step 10) the Handover to UTRAN Command message to the GERAN BSC  4120  in the BSSMAP Handover Command message, completing the handover preparation. 
     The GERAN BSC  4120  sends (in Step 11) the Intersystem to UTRAN Handover Command message, containing the Handover to UTRAN Command message, to the UE to initiate handover to GAN. The UE does not switch its audio path from GERAN to GAN until handover completion (i.e., until it sends the GA-CSR HANDOVER COMPLETE message) to keep the audio interruption short. 
     The UE accesses the GANC  4110  using (in Step 12) the GA-CSR HANDOVER ACCESS message, and provides the entire Intersystem to UTRAN Handover Command message received from GERAN. The GANC  4110  indicates (in Step 13) to the MSC  4115  that it has detected the UE, using Relocation Detect message. The MSC  4115  can optionally now switch the user plane from the source GERAN to the target GAN. Bi-directional voice traffic is now flowing (in Step 14) between the UE and MSC  4115 , via GANC  4110 . 
     The UE transmits (in Step 15) the GA-CSR HANDOVER COMPLETE message to indicate the completion of the handover procedure at its end. It switches the user from the GERAN user plane to the GAN user plane. 
     The target GANC  4110  indicates (in Step 16) the handover is complete, using the Relocation Complete message. If it had not done so before, the MSC  4115  now switches the user plane from source GERAN to target GAN. 
     Finally, the MSC  4115  tears (in Step 17) down the connection to the source GERAN, using Clear Command message. The source GERAN confirms (in Step 18) the release of GERAN resources allocated for this call, using Clear Complete message. 
     2. CS Handover from UTRAN to GAN 
     a) GANC Terminates Iu UP Packet 
       FIG. 42  illustrates CS handover from UTRAN to GAN in some embodiments. The description of the UTRAN to GAN Handover procedure assumes the following: (1) the UE is on an active call on the UTRAN, (2) the UE has been ordered by the RNC to make inter-frequency measurements (i.e., if the GAN cell has been allocated a different frequency value than is used in the UTRAN), (a) if the UE is in GAN preferred mode with an Event  2 A configured, the UE handles parameters associated with the Event  2 A in a GAN specific manner (as described in “Radio Resource Control (RRC) protocol specification”, 3GPP TS 25.331 standard, hereinafter “3GPP TS 25.331”) for the reporting of the EGAN, (b) when the UE is in GERAN/UTRAN preferred mode and an event  2 A has been configured for the GAN cell, the UE shall only send a measurement about the GAN cell, when this event is triggered and no UTRAN cells from the neighbor cell list of the UE satisfy the triggering condition of this Event (as described in 3GPP TS 25.331), (3) the UTRAN provides information on neighboring cells such that one of the cells in the neighbor list matches the cell associated with the GANC, as provided in the AS-related component of the system information obtained from GANC. 
     As shown in  FIG. 42 , the UE  4205  begins to include information about a GAN cell in the Measurement Report message sent (in Step 1) to the RNC  4215 . The UE  4205  reports the highest signal level for the GAN cell. This is not the actual measured signal level on the GAN, rather an artificial value allowing the UE  4205  to indicate preference for the GAN. 
     Based on UE measurement reports and other internal algorithms, the RNC  4215  decides to initiate handover to the GAN cell. The RNC  4215  starts the preparation phase of the Relocation procedure by sending (in Step 2) a Relocation Required message to the MSC, identifying the target (GAN) cell. 
     Next, steps 3 to 5 shown in  FIG. 42  are performed as described for steps 3-5 for GERAN to GAN Handover sub-section, above. The target GANC  4210  acknowledges (in Step 6) the handover request message, using Relocation Request Acknowledge message, indicating it can support the requested handover, and including a Physical Channel Reconfiguration message that indicates the radio channel to which the UE should be directed. 
     Next, the MSC  4220  sends (in Step 7) the Relocation Command message to the RNC  4215 , completing the relocation preparation. The RNC  4215  sends (in Step 8) the PHYSICAL CHANNEL RECONFIGURATION message to the UE  4205  to initiate handover to GAN. The UE does not switch its audio path from UTRAN to GAN until handover completion (i.e., until it sends the GA-CSR HANDOVER COMPLETE message) to keep the audio interruption short. 
     Next, Steps 9-16 shown in  FIG. 42  are performed similar to Steps 9-16 for GERAN to GAN Handover described above. Next, the MSC  4220  tears down (in Step 17) the connection to the source RNC, using Iu Release Command. Finally, the source RNC  4215  confirms (in Step 18) the release of UTRAN resources allocated for this call, using Iu Release Complete. 
     b) UE Terminates Iu UP Packet 
     Some embodiments utilize an alternative procedure for CS handover from UTRAN to GAN.  FIG. 43  illustrates steps performed during UTRAN to GAN in these embodiments. As shown, the UE begins to include (in Step 1) information about a GAN cell in the Measurement Report message sent to the RNC  4320 . The UE reports the highest signal level for the GAN cell. This is not the actual measured signal level on the GAN, rather an artificial value allowing the UE to indicate preference for the GAN. 
     Based on UE measurement reports and other internal algorithms, the RNC  4320  decides to initiate handover to the GAN cell. The RNC  4320  starts the preparation phase of the Relocation procedure by sending (in Step 2) a Relocation Required message to the MSC  4315 , identifying the target GAN cell. 
     The MSC  4315  requests (in Step 3) the target GANC  4310  to allocate resources for the handover using the Relocation Request message. The UE  4305  is identified by the included IMSI parameter. 
     The GANC  4310  sends (in Step 4) the GA-CSR ACTIVATE CHANNEL message to the UE  4305  including bearer path setup information received in the Relocation Request message, such as: (1) UDP port &amp; the IP address for the uplink RTP stream, (2) Radio Access Bearer (RAB) parameters, and (3) Iu UP parameters (e.g., Iu UP mode, where support mode is used for AMR voice calls). 
     Since Iu UP support mode is indicated, the UE  4305  sends (in Step 5) the Iu UP INITIALISATION packet to the IP address and UDP port indicated in the GA-CSR ACTIVATE CHANNEL message. This message is routed to the core network  4315  (e.g., the R4 media gateway). 
     The MSC  4315  responds (in Step 6) with the Iu UP INITIALISATION ACK packet. The MSC  4315  sends the message to the source IP address and UDP port number of the received INITIALISATION packet. The UE  4305  sends (in Step 7) the GA-CSR ACTIVATE CHANNEL ACK to the GANC  4310 . 
     The target GANC  4310  acknowledges (in Step 8) the handover request message, using Relocation Request Acknowledge message, indicating it can support the requested handover, and including a Physical Channel Reconfiguration message that indicates the radio channel to which the UE  4305  should be directed. 
     The GANC  4310  signals (in Step 9) the completion of the RAB establishment to the UE  4305  with the GA-CSR ACTIVATE CHANNEL COMPLETE message. An end-to-end audio path now exists between the UE  4305  and the MSC  4315 . The MSC  4315  sends (in Step 10) the Relocation Command message to the RNC  4320 , completing the relocation preparation. 
     The RNC  4320  sends (in Step 11) the PHYSICAL CHANNEL RECONFIGURATION message to the UE to initiate handover to GAN. The UE does not switch its audio path from UTRAN to GAN until handover completion (i.e., until it sends the GA-CSR HANDOVER COMPLETE message) to keep the audio interruption short. The UE accesses (in Step 12) the GANC  4310  using the GA-CSR HANDOVER ACCESS message, and provides the entire PHYSICAL CHANNEL RECONFIGURATION message received from RNC  4320 . 
     The GANC  4310  indicates (in Step 13) to the MSC  4315  that it has detected the UE, using Relocation Detect message. The MSC  4315  can optionally now switch the user plane from the source RNC  4320  to the target GANC  4310 . Bi-directional voice traffic is now flowing (in Step 14) between the UE and MSC  4315 , via GANC  4310 . 
     The UE transmits (in Step 15) the GA-CSR HANDOVER COMPLETE to indicate the completion of the handover procedure from its perspective. It switches the user from the UTRAN user plane to the GAN user plane. The target GANC  4310  indicates (in Step 16) the handover is complete, using the Relocation Complete message. If it has not done so before, the CN  4315  now switches the user plane from source RNC  4320  to target GANC  4310 . 
     Finally, the MSC  4315  tears (in Step 17) down the connection to the source RNC  4320 , using Iu Release Command. The source RNC  4320  confirms (in Step 18) the release of UTRAN resources allocated for this call, using Iu Release Complete. 
     3. CS Handover from GAN to GERAN 
       FIG. 44  illustrates the procedure to handover from GAN to GERAN in some embodiments. The procedure description in this sub-clause assumes the following: (1) the UE is on an active call in GAN Iu-mode, and (2) the GERAN becomes available and (a) the UE mode selection is GERAN/UTRAN-preferred, or (b) the UE mode selection is GAN-preferred and the UE begins to leave GAN coverage, based on its local measurements, received RTCP reports, as well as any uplink quality indications received from the GANC. The handover from GAN to GERAN procedure is always triggered by the UE. As shown in  FIG. 44 , the following steps are performed during handover from GAN to GERAN. 
     The GANC  4410  may send (in Step 1) a GA-CSR UPLINK QUALITY INDICATION when there is a problem with the uplink quality for the ongoing call. Uplink Quality Indication is information sent by the GANC to the UE indicating the crossing of an uplink quality threshold in the uplink direction. Whenever the UE receives an indication of bad quality, it should start the handover procedure, as described in the next step. Alternatively, UE can use its local measurements or received RTCP reports, to decide to initiate the handover procedure. 
     As shown, the UE  4405  sends (in Step 2) the GA-CSR HANDOVER INFORMATION message to the GANC  4410  indicating the Channel Mode and a list of target GERAN cells, identified by CGI, in order of preference (e.g. ranked by C 1  path loss parameter) for handover, and includes the received signal strength for each identified GERAN cell. This list is the most recent information available from the GSM RR subsystem. In addition, the GA-CSR HANDOVER INFORMATION message may include a list of target UTRAN cells ranked in order of preference for handover, and the received signal strength for each identified UTRAN cell. 
     If the Serving GANC selects a target GERAN cell, the handover to GERAN procedure is performed. The Serving GANC  4410  starts the handover preparation by signaling (in Step 3) to the MSC  4420  the need for handover, using Relocation Required, and including the GERAN cell list provided by the UE. The GANC may include only a subset of the cell list provided by the UE. 
     The MSC  4420  then selects a target GERAN cell and requests it (in Step 4) to allocate the necessary resources, using Handover Request. The target GERAN BSC  4415  builds a Handover Command message providing information on the channel allocated and sends it (in Step 5) to the MSC  4420  through the Handover Request Acknowledge message. 
     The MSC  4420  signals (in Step 6) the GANC  4410  to handover the UE  4405  to the GERAN, using Relocation Command message, ending the handover preparation phase. The GANC transmits (in Step 7) the GA-CSR HANDOVER COMMAND to the UE including the details sent by the GERAN on the target resource allocation. 
     Next, the UE  4405  transmits (in Step 8) the “Um: Handover Access” message containing the handover reference element to allow the target GERAN BSC  4415  to correlate this handover access with the Handover Command message transmitted earlier to the MSC in response to the Handover Required. The target GERAN BSC  4415  confirms (in Step 9) the detection of the handover to the MSC  4420 , using the Handover Detect message. 
     The MSC  4420  may at this point switch (in Step 10) the user plane to the target BSS. The GERAN BSC  4415  provides (in Step 11) Physical Information to the UE (i.e., Timing Advance) to allow the UE to synchronize with the GERAN. The UE  4405  signals (in Step 12) to the GERAN BSC  4415  that the handover is completed, using Handover Complete. 
     The GERAN BSC  4415  confirms (in Step 13) to the MSC  4420  the completion of the handover, via Handover Complete message. The MSC  4420  may use the target CGI used in the Handover procedure for charging purposes. 
     Bi-directional voice traffic is now flowing (in Step 14) between the UE  4405  and MSC  4420 , via the GERAN BSC  4415 . On receiving the confirmation of the completion of the handover, the MSC  4420  indicates (in Step 15) to the GANC to release any resources allocated to the UE, via the Iu Release Command. 
     Next, GANC  4415  commands (in Step 16) the UE  4405  to release resources, using the GA-CSR RELEASE message. The GANC  4410  confirms (in Step 17) resource release to MSC  4420  using the Iu Release Complete message. 
     The UE  4405  confirms (in Step 18) resource release to the GANC  4410  using the GA-CSR RELEASE COMPLETE message. The UE  4405  may finally deregister (in Step 19) from the GANC, using GA-RC DEREGISTER message. 
     4. CS Handover from GAN to UTRAN 
       FIG. 45  illustrates the procedure to handover from GAN to UTRAN in some embodiments. The procedure description assumes the following: (1) the UE is on an active call on the GAN, (2) the UE is capable of operating in all of the GAN, GERAN and UTRAN modes, (3) the UTRAN becomes available and (a) the UE is in GERAN/UTRAN-preferred mode, or (b) the UE mode selection is GAN preferred and begins to leave GAN coverage, based on its local measurements, received RTCP reports, as well as any uplink quality indications received from the GANC. The handover from GAN procedure is always triggered by the UE. As shown in  FIG. 45 , the following steps are performed during handover from GAN to UTRAN. 
     The GANC  4510  may send (in Step 1) a GA-CSR UPLINK QUALITY INDICATION if there is a problem with the uplink quality for the ongoing call. Uplink Quality Indication is information sent by the GANC  4510  to the UE  4505  indicating the crossing of an uplink quality threshold in the uplink direction. Whenever the UE  4505  receives an indication of bad quality, it should start the handover procedure, as described in the next step. Alternatively, UE can use its local measurements or received RTCP reports, to decide to initiate the handover procedure. 
     Next, the UE  4505  sends (in Step 2) the GA-CSR HANDOVER INFORMATION message to the Serving GANC indicating the Channel Mode and a list of candidate target UTRAN and GERAN cells, in order of preference for handover, and includes the received signal strength for each identified cell. The UTRAN cells are identified by the PLMN ID, the LAC and the 3G Cell identity (defined in 3GPP TS 25.331). 
     If the Serving GANC  4510  selects UTRAN as the target RAT, the handover to UTRAN procedure is performed. The Serving GANC  4510  starts the handover preparation by signaling (in Step 3) to the MSC  4520  the need for handover, using Relocation Required and including the UTRAN cell list provided by the UE  4505 . The GANC  4510  may include only a subset of the cell list provided by the UE  4505 . 
     The MSC  4520  starts the handover procedure towards the target RNC  4515  identified by the Serving GANC. The MSC  4520  requests (in Step 4) from the target RNC  4515  to allocate the necessary resources using Relocation Request. The target RNC  4515  builds a Physical Channel Reconfiguration message providing information on the allocated UTRAN resources and sends it (in Step 5) to the MSC  4520  through the Relocation Request Acknowledge message. 
     Next, the MSC  4520  signals (in Step 6) the Serving GANC  4510  to handover the UE to the UTRAN, using Relocation Command message (which includes the Physical Channel Reconfiguration message), ending the handover preparation phase. 
     The Serving GANC  4510  transmits (in Step 7) the GA-CSR HANDOVER COMMAND to the UE including the details sent by the UTRAN on the target resource allocation. Target RNS  4515  achieves (in Step 8) uplink synchronization on the Uu interface. 
     The target RNC  4515  confirms (in Step 9) the detection of the handover to the MSC, using the Relocation Detect message. The MSC  4520  may at this point switch (in Step 10) the user plane to the target RNS  4515 . 
     Next, the UE  4505  signals (in Step 11) to the UTRAN RNC  4515  that the handover is completed, using Handover to UTRAN Complete. The UTRAN RNC  4515  confirms (in Step 12) to the MSC  4520  the completion of the handover, via Relocation Complete message. If the user plane has not been switched in step 10, the MSC  4520  switches the user plane to the target RNS. 
     Bi-directional voice traffic is now flowing (in Step 13) between the UE  4505  and MSC  4520 , via the UTRAN RNC  4515 . On receiving the confirmation of the completion of the handover, the MSC  4520  indicates (in Step 14) to the Serving GANC  4510  to release any resources allocated to the UE, via the Iu Release Command. 
     The Serving GANC  4510  then commands (in Step 15) the UE  4505  to release resources, using the GA-CSR RELEASE message. The Serving GANC  4510  confirms (in Step 16) resource release to MSC  4520  using the Iu Release Complete message. 
     The UE  4505  confirms (in Step 17) resource release to the Serving GANC  4510  using the GA-CSR RELEASE COMPLETE message. The UE  4505  may finally deregister (in Step 18) from the Serving GANC  4510 , using GA-RC DEREGISTER message. 
     N. GA-PSR Connection Handling 
     The Iu-mode GA-PSR connection is a logical connection between the UE and the GANC for the PS domain. A GA-PSR connection is established when the upper layers in the UE request the establishment of a PS domain signaling connection and the UE is in GA-PSR-IDLE state; i.e., no GA-PSR connection exists. When a successful response is received from the network, GA-PSR replies to the upper layer that the PS domain signaling connection is established and the UE has entered the equivalent of the RRC connected mode (i.e., the GA-PSR-CONNECTED state). 
     1. GA-PSR Connection Establishment 
       FIG. 46  illustrates successful and unsuccessful establishment of the GA-PSR Connection in some embodiments. As shown, the UE  4605  initiates GA-PSR connection establishment by sending (in Step 1) the GA-PSR REQUEST message to the GANC  4610 . This message contains the Establishment Cause indicating the reason for GA-PSR connection establishment. When the GANC  4610  determines that the GA-PSR connection request can be accepted, the GANC  4610  signals the acceptance of the connection request to the UE  4605  by sending (in Step 2) the GA-PSR REQUEST ACCEPT and the UE enters the GA-PSR-CONNECTED state. Alternatively, when the GANC  4610  determines that the GA-PSR connection request has to be rejected, the GANC  4610  sends (in Step 3) a GA-PSR REQUEST REJECT to the UE ZC05 indicating the reject cause, completing the procedure. 
     2. GA-PSR Connection Release 
       FIG. 47  illustrates release of the logical GA-PSR connection between the UE and the GANC in some embodiments. The following steps are performed during the release. As shown, the SGSN  4715  indicates to the GANC  4710  to release the PS resources allocated to the UE by sending (in Step 1) the RANAP Iu Release Command message to the GANC  4710 . 
     Next, the GANC  4710  confirms (in Step 2) resource release to SGSN  4715  using the Iu Release Complete message. Next, the GANC  4710  commands (in Step 3) the UE  4705  to release resources, using the GA-PSR RELEASE message. Finally, the UE  4705  confirms (in Step 4) resource release to the GANC  4710  using the GA-PSR RELEASE COMPLETE message and the GA-PSR state in the UE changes to GA-PSR-IDLE. 
     O. PS Security Mode Control 
       FIG. 48  illustrates the message flow for PS security mode control in some embodiments. As shown, SGSN  4815  sends (in Step 1) the RANAP Security Mode Command message to GANC  4810 . This message contains the integrity key (IK) and allowed algorithms, and optionally the encryption key (CK) and allowed algorithms. 
     Next, the GANC  4810  sends (in Step 2) the GA-PSR SECURITY MODE COMMAND message to the UE  4805 . This message indicates the integrity protection and encryption settings (i.e., that are applicable after relocation to UTRAN), and a random number. The UE stores the information for possible future use after a relocation to UTRAN. 
     Next, the UE  4805  computes a message authentication code (MAC) based on the random number, the UE IMSI and the integrity key calculated by the UE. The UE  4805  then sends (in Step 3) the GA-PSR SECURITY MODE COMPLETE message to the GANC  4810  to signal its selected algorithm and the computed MAC. 
     The GANC  4810  then verifies the MAC using the random number, the UE IMSI and the integrity key provided by the SGSN in step 1. When the GANC verifies the MAC to be correct it sends (in Step 4) the Security Mode Complete message to the SGSN  4815 . The MAC proves that the identity that is authenticated to the GANC is the same as the identity authenticated to the core network. 
     P. PS NAS Signaling Procedures 
     After GA-PSR connection establishment, NAS signaling may be transfer from SGSN-to-UE and from UE-to-SGSN. 
     1. SGSN-to-UE NAS Signaling 
       FIG. 49  illustrates SGSN-to-UE PS NAS signaling in some embodiments. As shown, for SGSN-to-UE NAS signaling, the SGSN  4915  sends (in Step 1) a NAS PDU to the GANC via the RANAP Direct Transfer message. The GANC  4910  encapsulates the NAS PDU within a GA-PSR DL DIRECT TRANSFER message and forwards (in Step 2) the message to the UE  4905  via the existing TCP connection. 
     2. UE-to-SGSN NAS Signaling 
       FIG. 50  illustrates UE-to-SGSN NAS signaling in some embodiments. As shown, the UE  5005  receives a request from the NAS layer to transfer an uplink NAS PDU. Assuming the required signaling connection already exists, the UE  5005  encapsulates the NAS PDU within a GA-PSR UL DIRECT TRANSFER message and sends (in Step 1) the message to the GANC  5010 . The GANC  5010  relays (in Step 2) the received message to the SGSN  5015  that is currently serving the UE via the RANAP Direct Transfer message. 
     Q. GA-PSR Packet Transport Channel Management Procedures 
     The GA-PSR Packet Transport Channel (GA-PSR PTC) provides the association between the UE and the network for the transport of GPRS user data over the Up interface (i.e., via the GAN in Iu-mode). The PTC uses the GTP-U protocol running over UDP transport. The endpoint addresses of the PTC are identified by the IP addresses and UDP ports assigned to the PTC in the UE and network during the PTC activation procedure. The UDP port number for GTP-U is as defined in “UTRAN Iu interface data transport &amp; transport signalling”, 3GPP TS 25.414 standard, hereinafter “3GPP TS 25.414”. 
     Multiple PTC instances between a UE and the network may be activated at the same time, using the same endpoint addresses. Each PTC instance is assigned unique GTP-U Tunnel Endpoint IDs (one on the UE and one on the network) during the activation procedure. The UE and GANC manage the activation and deactivation of the PTC instances based on the requests for data transfer and the configurable PTC Timer. 
     1. States of the GA-PSR Packet Transport Channel 
     The UE in the GA-PSR-CONNECTED state can be in one of two PTC substates: PTC-STANDBY or PTC-ACTIVE. The PTC-STANDBY substate is the initial/default PTC substate of the UE when in the GA-PSR-CONNECTED state in GAN mode. The UE is not able to send or receive GPRS user data to or from the network. The UE needs to activate the PTC before sending any GPRS user data. When the UE successfully establishes a PTC, the UE transitions to the PTC-ACTIVE substate. 
     In PTC-ACTIVE substate, the UE is in the GA-PSR-CONNECTED state and the PTC is active between the UE and the network and the UE is able to send and receive GPRS user data to and from the network. Several events can trigger the GA-PSR PTC activation on the UE side. These events include the UE initiates the uplink user data transfer or the GANC initiates PTC activation; i.e., the UE receives a GA-PSR-ACTIVATE-PTC-REQUEST message from the GANC. 
     On successful PTC activation and in parallel with transition to the PTC-ACTIVE substate, the UE starts the PTC Timer. When the PTC Timer expires, the UE sends a message to the GANC to initiate PTC deactivation. On successful PTC deactivation, the UE transitions to PTC-STANDBY substate. 
     At any time while in the GA-PSR-CONNECTED state and the PTC-ACTIVE substate, the UE may receive the GA-PSR RELEASE message. In addition to requesting release of the GA-PSR session, this is interpreted by the UE as an implicit PTC deactivate command. 
     At any time while in GAN mode, if the serving RR entity is switched to GSM-RR/UTRAN-RRC, the GA-PSR is disconnected from the GPRS SAPs and the UE enters GERAN/UTRAN mode. Simultaneously, the UE will release the associated PTC regardless of the PTC Timer status. 
     The UE GA-PSR entity maintains one PTC for each active PDP context. The PTC Timer is restarted whenever any uplink user data packet is sent or downlink user data packet is received related to the PDP context. The PTC Timer value is provided to the UE as part of the GAN Registration procedure (i.e., in the GA-RC REGISTER ACCEPT message). 
     2. PTC Initial Activation 
       FIG. 51  depicts the Packet Transport Channel initial activation procedure, assuming the UE is in the GA-PSR-IDLE state. As shown, the following steps are performed. The GA-PSR Connection Establishment procedure is performed (in Step 1) as described in GA-PSR connection establishment sub-section, above. The UE  5105  transitions to the GA-PSR-CONNECTED state and the PTC-STANDBY substate. Next, additional PS signaling procedures are performed (in Step 2). Examples of these signaling procedures are illustrated in PDP Context Activation and Network Requested PDP Context Activation sub-sections, below. 
     Next, the SGSN  5115  initiates (in Step 3) the RAB Assignment procedure and includes the RAB-ID, the CN Transport Layer Address (IP address) and the CN Iu Transport Association (GTP-U Terminal Endpoint Identifier, TEID) for user data. The GANC  5110  sends (in Step 4) the GA-PSR ACTIVATE PTC REQUEST message to the UE to request activation of the Packet Transport Channel. The message includes the RAB-ID, a TEID that the GANC assigns to the UE, and the GANC IP Address and GANC TEID. If the GANC is configured to allow the UE to send PTC packets (i.e., GTP-U messages) directly to the SGSN (i.e., the configuration illustrated in  FIG. 17 ), the GANC sets the GANC IP Address to the CN IP Address and the GANC TEID to the CN TEID; otherwise, the GANC assigns a local address as the GANC IP address and a GANC-allocated TEID as the GANC TEID and sends this information to the UE (i.e., the configuration illustrated in  FIG. 18 ). The UE  5105  acknowledges (in Step 5) the PTC activation. 
     The GANC  5110  sends (in Step 6) the RAB Assignment Response message to the SGSN  5115  to complete the RAB Assignment procedure. If the GANC is configured to allow the SGSN  5115  to send GTP-U messages directly to the UE  5105  (i.e., the configuration illustrated in  FIG. 17 ), the GANC  5110  sets the RAN IP Address to the UE&#39;s IP Address and the RAN TEID to the TEID assigned to the UE by the GANC; otherwise, the GANC assigns a local address as the RAN IP address and a GANC-allocated TEID as the RAN TEID and sends this information to the SGSN (i.e., the configuration illustrated in  FIG. 18 ). 
     Next, the GANC  5110  signals (in Step 7) the completion of the RAB establishment to the UE  5105  with the GA-PSR ACTIVATE PTC COMPLETE message. On receipt of the message, the UE transitions to the PTC-ACTIVE substate and starts the PTC Timer. Next, additional PS signaling procedures are performed (in Step 8). Examples of these PS signaling are illustrated in PDP Context Activation and Network Requested PDP Context Activation sub-sections, below. The UE  5105  initiates (in Step 9) uplink user data transfer via the established PTC and the SGSN  5115  may use the same transport channel to send downlink user data packets. 
     3. PTC Data Transfer 
       FIG. 52  illustrates the transfer of GPRS user data packets via the GAN Packet Transport Channel. This scenario assumes that user data is carried transparently between the UE and core network (i.e., the configuration illustrated in  FIG. 17 ). As shown, the following steps are performed. 
     When required, the GAN PTC is established (in Step 1) as specified in PTC Initial Activation sub-section, above. Upon the GA-PSR PTC establishment, the UE  5205  enters the PTC-ACTIVE substate and starts the PTC Timer. Next, the UE  5205  initiates (in Step 2) the transfer of an uplink user data packet using the standard GTP-U protocol as specified in “GPRS Tunneling Protocol (GTP) across the Gn and Gp interface”, 3GPP TS 29.060 standard, hereinafter “3GPP TS 29.060” and restarts the PTC Timer. 
     Next, the SGSN  5215  transfers (in Step 3) downlink user data packet utilizing the same PTC associated with the specific PDP context. Downlink user data packets are transferred using the standard GTP-U protocol as specified in 3GPP TS 29.060. Upon receiving the downlink data packet, the UE restarts the associated PTC Timer. Additional uplink and downlink user data packets are transferred (in Step 4) via the same PTC as described in steps 2 and 3, respectively. After each transmission/reception, the UE restarts the PTC Timer. If the configuration illustrated in  FIG. 18  is used, then the uplink GTP-U packets are sent from UE to GANC, then relayed from GANC to SGSN; likewise, downlink GTP-U packets are sent from SGSN to GANC, then relayed from GANC to UE. 
     4. MS initiated PTC Deactivation 
       FIG. 53  depicts the scenario when the UE deactivates the Packet Transport Channel after the PTC Timer expires. The UE is in the GA-PSR-CONNECTED state and the PTC-ACTIVE substate. As shown, the following steps are performed. 
     The PTC Timer associated with one of the active packet transport channels expires (in Step 1). The UE  5305  sends (in Step 2) the GA-PSR DEACTIVATE PTC REQUEST message to the GANC  5310 , including the RAB-ID to identify the PTC and indicating the normal release as a cause for deactivation. Alternatively, the UE may indicate PTC timer expiry as the cause for deactivation. 
     Next, the GANC  5310  sends (in Step 3) a RAB Release Request message to the SGSN  5315  to request the release of the associated RAB. The SGSN  5315  responds (in Step 4) with the RAB Assignment Request indicating release. 
     The GANC  5310  responds (in Step 5) to the UE  5305  with a GA-PSR DEACTIVATE PTC ACK message to acknowledge successful deactivation. The UE  5305  transitions to the PTC-STANDBY substate. The GANC  5310  sends (in Step 6) the RAB Assignment Response message to notify the SGSN  5315  that the RAB Release procedure is complete. 
     5. MS Initiated PTC Re-activation 
       FIG. 54  depicts the scenario when in some embodiments the UE initiates re-activation of the Packet Transport Channel while in the GA-PSR-CONNECTED and PMM-CONNECTED states; e.g., a PS signaling connection and active PDP context exists between the UE and CN but the PTC was previously deactivated by the UE due to PTC Timer expiry. As shown, the following steps are performed. The UE is in the GA-PSR-CONNECTED state and the PTC-STANDBY substate. The UE is in the PMM-CONNECTED state (i.e., a PS signaling connection and an active PDP context exists). 
     When the UE  5405  has a PDU to send, the UE  5405  sends (in Step 1) the Service Request message (with Service type value “Data”) to the GANC  5410  in the GA-PSR UL DIRECT TRANSFER message. Next, the GANC  5410  forwards (in Step 2) the Service Request over the existing signaling connection to the SGSN  5415  using the RANAP Direct Transfer message. 
     The SGSN  5415  may optionally initiate (in Step 3) the Security Mode Control procedure described in Security Mode Control sub-section, above. The SGSN  5415  sends (in Step 4) a Service Accept message to the GANC  5410 . The GANC  5410  forwards (in Step 5) the message to the UE. 
     Next, the UE  5405 , GANC  5410  and SGSN  5415  establish (in Step 6) the GA-PSR Packet Transport Channel (PTC) as described in steps 3-7 in PTC Initial Activation Sub-section, above. The UE transitions to the PTC-ACTIVE substate and starts the PTC Timer. Finally, the UE  5405  sends (in Step 7) the uplink PDU. Additional data transfer may also take place. 
     6. Network Initiated PTC De-activation 
       FIG. 55  depicts the scenario when the network initiates de-activation of the Packet Transport Channel in some embodiments. The UE is in the GA-PSR-CONNECTED state and the PTC-ACTIVE substate. As shown, the following steps are performed. 
     Optionally, the GANC  5510  may initiate the PTC de-activation procedure; e.g., as a result of an error handling procedure. If so, the GANC  5510  sends (in Step 1) the RAB Release Request message to the SGSN  5515 . 
     The SGSN  5515  sends (in Step 2) a RAB Assignment Request to request the release of the associated RAB. The release request may include one or more RABs. Next, the GANC  5510  requests deactivation of the associated GA-PSR PTC by sending (in Step 3) the GA-PSR DEACTIVATE PTC REQUEST message to the UE  5505 . 
     The UE  5505  transitions to the PTC-STANDBY substate, stops the PTC Timer and sends (in Step 4) the acknowledgment back to the GANC. Steps 3 and 4 are repeated for each additional RAB/PTC that needs to be released. Finally, the GANC  5510  notifies (in Step 5) the SGSN  5515  that the release was successful. 
     7. Network Initiated PTC Re-activation 
       FIG. 56  depicts the scenario in some embodiments when the network initiates re-activation of the Packet Transport Channel while the UE is in the GA-PSR-CONNECTED and PMM-CONNECTED states; e.g., a PS signaling connection and active PDP context exists between the UE and CN but the PTC was previously deactivated. The UE is in the GA-PSR-CONNECTED state and the PTC-STANDBY substate. The UE is in the PMM-CONNECTED state (i.e., a PS signaling connection and an active PDP context exists). As shown, the following steps are performed. 
     When the SGSN  5615  has a PDU to send to the UE  5605 , the SGSN  5615  may optionally initiate (in Step 1) the Security Mode Control procedure described in Security Mode Control sub-section, above. The UE  5605 , GANC  5610  and SGSN  5615  establish (in Step 2) the GA-PSR Packet Transport Channel (PTC) as described in steps 3-7 in PTC Initial Activation sub-section, above. The UE transitions to the PTC-ACTIVE substate and starts the PTC Timer. The SGSN  5615  then sends (in Step 3) the downlink PDU. Additional data transfer may also take place. 
     8. Implicit PTC De-activation Due to UE De-registration 
     As part of the GAN de-registration procedure, the GANC needs to release all resources allocated to the UE. GAN de-registration may be initiated either explicitly by the UE or implicitly by the GANC if the loss of the signaling connection is detected (as described in De-Registration sub-section, above).  FIG. 57  illustrates implicit PTC deactivation procedure in some embodiments. Initially, one or more GA-PSR PTCs associated with a UE are in the PTC-ACTIVE state. As shown, the following steps are performed. 
     The GAN de-registration procedure is initiated (in Step 1) for the UE  5705  either by the UE  5705  or GANC  5710 . Optionally, any outstanding resources associated with the CS Domain are released (in Step 2). 
     The GANC  5710  initiates (in Step 3) the Iu release procedure to release the corresponding RABs. The SGSN  5715  responds (in Step 4) with Iu Release Command. 
     Upon receiving the Iu Release Command, the GANC  5710  locally deactivates (in Step 6) all associated PTCs and responds (in Step 6) to the SGSN  5715  with an Iu Release Complete message. 
     R. PDP Context Activation 
       FIG. 58  illustrates the successful UE-initiated PDP Context Activation procedure in some embodiments, assuming the UE is in GA-PSR-IDLE state. As shown, the following steps are performed. 
     The GA-PSR Connection Establishment procedure is performed (in Step 1) as described in GA-PSR Connection Establishment Sub-section, above. The GANC  5810  establishes an SCCP connection to the SGSN and forwards (in Step 2) the Service Request message (with Service type value “Signaling”) to the SGSN  5815  using the RANAP Initial UE Message. Subsequent NAS messages between the UE and core network will be sent between GANC and SGSN using the RANAP Direct Transfer message. 
     The SGSN  5815  may optionally authenticate (in Step 3) the UE using standard UTRAN authentication procedures. The SGSN  5815  may optionally initiate (in Step 4) the Security Mode Control procedure described in Security Mode Control Sub-section, above. The SGSN  5815  responds (in Step 5) with a Service Accept message. The GANC  5810  forwards (in Step 5) the message to the UE  5805 . 
     The UE  5805  then sends (in Step 6) the Activate PDP Context Request message providing details on the PDP context to the SGSN  5815 . This message is contained within the GA-PSR UL DIRECT TRANSFER between the UE  5805  and the GANC  5810 . The GANC  5810  forwards (in Step 6) the Activate PDP Context Request message to the SGSN  5815 . 
     Next, the UE  5805 , GANC  5810 , and SGSN  5815  establish (in Step 7) the GA-PSR Packet Transport Channel (PTC) as described in steps 3-7 in PTC Initial Activation, above. The SGSN  5815  indicates (in Step 8) the PDP context establishment is complete using the Activate PDP Context Accept message to the GANC. GANC forwards this message to the UE in the GA-PSR DL DIRECT TRANSFER message. Finally, the UE  5805  and CN  5815  exchange (in Step 9) user data transfer via the established PTC. 
     S. Network Requested PDP Context Activation 
       FIG. 59  illustrates the successful Network-Requested PDP Context Activation procedure in some embodiments, assuming the UE is in GA-PSR-IDLE state. Initially, the SGSN received downlink user data to transfer to the UE and the associated RAB is not established. The UE is in PMM-IDLE state. As shown, the SGSN  5915  sends (in Step 1) the RANAP Paging message to the UE  5905  via the GANC  5910  to locate the user. The paging request indicates paging for PS Domain signaling. 
     The GANC  5910  forwards (in Step 2) the paging information to the UE  5905  in the GA-PSR PAGING REQUEST message. The GA-PSR Connection Establishment procedure is performed (in Step 3) as described in GA-PSR Connection Establishment Sub-section, above. Alternatively, rather than using the GA-PSR Connection Establishment procedure, the UE  5905  may send the GA-PSR PAGING RESPONSE message (in Step 3) and then transition to the GA-PSR CONNECTED state. 
     The GANC  5910  establishes an SCCP connection to the SGSN and forwards (in Step 4) the Service Request message (with Service type value “Paging response”) to the SGSN  5915  using the RANAP Initial UE Message. Subsequent NAS messages between the UE  5905  and core network  5915  will be sent between GANC  5910  and SGSN  5915  using the RANAP Direct Transfer message. 
     The SGSN  5915  may optionally authenticate (in Step 5) the UE  5905  using standard UTRAN authentication procedures. The SGSN  5915  may optionally initiate (in Step 6) the Security Mode Control procedure described in Security Mode Control Sub-section, above. 
     Next, the SGSN  5915  sends (in Step 7) the Request PDP Context Activation message to the GANC  5910 . The GANC  5910  forwards (in Step 7) this message to the UE  5905  in the GA-PSR DL DIRECT TRANSFER message. The UE  5905  sends (in Step 8) the Activate PDP Context Request message providing details on the PDP context to the SGSN  5915 . This message is contained within the GA-PSR UL DIRECT TRANSFER between the UE and the GANC. The GANC  5910  forwards (in Step 8) the Activate PDP Context Request message to the SGSN  5915 . 
     The UE  5905 , GANC  5910 , and SGSN  5915  establish (in Step 9) the GA-PSR Packet Transport Channel (PTC) as described in steps 3-7 in PTC Initial Activation Sub-section, above. The SGSN  5915  indicates (in Step 10) the PDP context establishment is complete using the Activate PDP Context Accept message to the GANC. GANC forwards this message to the UE in the GA-PSR DL DIRECT TRANSFER message. Finally, the UE  5905  and SGSN  5915  exchange (in Step 11) user data transfer via the established PTC. 
     T. SRNS Relocation Between UTRAN and GAN 
     The SRNS Relocation procedure is performed to move one or more PS sessions between Iu mode GAN and UTRAN. It relocates the Iu-ps connection point at the GAN/UTRAN (in all cases) and at the SGSN (for inter-SGSN Relocation case only). 
     Support for the Iur interface between UTRAN and GAN is not described in this document. Therefore, only the Combined Hard Handover and SRNS Relocation is applicable for GAN-UTRAN SRNS Relocation. Consequently, only the “UE Involved” Relocation Type is supported. 
     1. SRNS Relocation from UTRAN to GAN 
     a) Preparation Phase 
       FIG. 60  illustrates the UTRAN to GAN SRNS relocation preparation phase in some embodiments. As shown, the following steps are performed. 
     The UE  6005  has one or more active PDP Contexts with active RABs in the UTRAN. Next, the UE  6005  detects a GAN  6015 , performs (in Step 2) the Registration procedures and enters GA-RC-REGISTERED state with valid GAN cell identity information. 
     The Measurement Control message (in Step 3) from the RNC  6010  to UE  6005  includes this GAN&#39;s cell identity. The UE begins to include the GAN cell information in the Measurement Report sent (in Step 3a) to the RNC. In that message, it sets the GAN cell&#39;s signal strength indicator to the highest possible value. 
     Next, the RNC  6010  decides to initiate a Combined Hard Handover and SRNS Relocation procedure. This decision is made based on the measurement reports and vendor/operator specific criteria. Upon deciding to initiate the Relocation, the RNC  6010  sends (in Step 4) Relocation Required to the SGSN. 
     The SGSN  6020  determines the target cell is the GANC, based on the contents of Relocation Required. The SGSN  6020  then sends (in Step 5) the Relocation Request to the GANC  6015 . 
     Upon receiving Relocation Request message, the GANC  6015  will setup (in Step 6) Packet Transport Channel(s) as described in steps 4, 5 and 7 in PTC Initial Activation Sub-section, above as needed with appropriate attributes, as defined in the message. The GANC  6015  will then send (in Step 6a) a Relocation Request Acknowledge to the SGSN. 
     b) Execution Phase 
       FIG. 61  illustrates UTRAN to GAN SRNS Relocation Execution Phase in some embodiments. As shown, the following steps are performed. 
     Upon receiving the positive acknowledgement from the GANC  6115  to serve the UE  6105 , the SGSN  6120  initiates the Execution Phase by sending (in Step 1) the Relocation Command to the RNC  6110 . The RNC  6110  instructs the UE  6105  by sending (in Step 2a) the Physical Channel Reconfiguration message to initiate the physical layer switch to move to the GAN. 
     When the QoS attributes of any of the active RABs require lossless in-sequence SDU Delivery (lossless PDCP), then the RNC  6110  starts forwarding (in Step 2b) GTP PDUs to the GANC  6115  while still transmitting them in the downlink direction to the UE  6105 . This forwarding is routed via the Iu_PS interface. The GANC may buffer, transmit in the downlink, or discard these forwarded GTP PDUs, depending on the QoS profile, network conditions, and whether it supports Lossless Relocation. Specific implementation is vendor and/or operator specific. In addition, the GANC may delay the start of the downlink transmission until Step 5 below to synchronize the GTP-U sequence numbers. 
     The RNC sends (in Steps 2c and 3a) the Forward SRNS Context message to the GAN via the SGSN. In this message, the next-expected sequence number of uplink and downlink GTP-U packets are indicated to the GANC by the old SRNS. If the QoS attributes require and GANC supports Lossless Relocation, then these sequence numbers are used to ensure in-sequence delivery of GTP PDUs. 
     Immediately after receiving the Physical Channel Reconfiguration message, the UE  6105  sends (in Step 3b) GA-PSR-HANDOVER-COMPLETE message to the GANC  6115 . Upon receiving this message and the Forward SRNS Context message sent from the SGSN  6120  (in Step 3a), the GANC  6115  becomes the Serving RNC. 
     Immediately upon receiving the GA-PSR-HANDOVER-COMPLETE message from the UE, the GANC  6115  sends (in Step 4) the Relocation Detect message to the SGSN  6120 . When the UE supports Lossless Relocation and one or more RABs QoS attribute requires it, the UE initiates (in Step 5) a GTP-U sequence number exchange procedure with the GANC over the newly established PTC. When the GANC  6115  supports Lossless Relocation and one or more RABs QoS attribute requires it, it may also initiate a GTP-U sequence number exchange procedure, if the procedure had not been already initiated by the UE. 
     Upon completion of the GTP-U sequence number exchange procedure, the GANC  6115  sends (in Step 6) Relocation Complete message to the SGSN. If the GTP-U sequence number exchange is skipped (either due to lack of support in UE and/or GAN or QoS attributes did not require it), then the Relocation Complete is sent right after the Relocation Detect message. The active RABs and PDP contexts are now moved to between UE, GANC and SGSN. The SGSN  6120  then releases (in Step 7) the Iu_PS connection with the old RNC  6110 . When the Routing Area of the GANC cell (as indicated by the GANC to the UE) is different from that under the old RNC, then the UE  6105  performs (in step 8) Routing Area Update procedure. 
     2. SRNS Relocation from GAN to UTRAN 
     a) Preparation Phase 
       FIG. 62  illustrates GAN to UTRAN SRNS Relocation Preparation Phase in some embodiments. As shown, the followings steps are performed. 
     The UE  6205  is (in Step 1) in active packet flow exchange with active PDP Context(s) and PTCs in the GAN. The GANC  6215  may send (in Step 2) a GA-PSR UPLINK QUALITY INDICATION if there is a problem with the uplink quality for the ongoing session. Uplink Quality Indication is information sent by the GANC  6215  to the UE  6205  indicating the crossing of an uplink quality threshold in the uplink direction. Whenever the UE receives an indication of bad quality, it should start the relocation procedure, as described in the next step. Alternatively, UE can use its local measurements to decide to initiate the handover procedure. 
     Next, the UE decides to initiate an SRNS Relocation from GAN to UTRAN by sending (in Step 3) GA-PSR-HANDOVER-INFORMATION message to the GANC  6215 . Specific criteria for this decision would include the case of the UE leaving GAN coverage (e.g., based on deteriorating WLAN signal quality). 
     The GANC  6215  selects a target RNC based on the contents of the GA-PSR-HANDOVER-INFORMATION message (e.g., the RNC serving the cell identified by the UE as having the best signal quality). The GANC  6215  sends (in Step 4) Relocation Required message to the SGSN  6220  containing the selected RNC information. 
     The SGSN  6220  sends (in Step 5) a Relocation Request to the target RNC  6210 . The RNC  6210  performs (in Step 6) the necessary allocation of radio and Iu transport resources and returns (in Step 7) Relocation Request Acknowledge message to the SGSN. This message contains channelization information needed by UE to access UTRAN. 
     b) Execution Phase 
       FIG. 63  illustrates GAN to UTRAN SRNS Relocation Execution Phase in some embodiments. As shown, the followings steps are performed. 
     The SGSN  6320  begins the Execution Phase by issuing (in Step 1) Relocation Command to the GANC  6315 . The message contains the channel access information in the target UTRAN cell. The GANC  6315  sends (in Step 2a) GA-PSR-HANDOVER-COMMAND to the UE  6305 . This message contains the information from the Relocation Command received in Step 1 earlier. The GANC may suspend downlink GTP PDU transfer at this point. If GANC supports Lossless SRNS Relocation and any of existing RABs&#39; QoS requires it, the GANC may initiate (in Step 2c) forwarding of GTP PDUs to the target RNC  6310  via the SGSN  6320 . 
     The GANC  6315  also sends (in Steps 2b and 3) Forward SRNS Context to the target RNC via the SGSN. As shown, the GANC sends the Forward SRNS Context message (in Step 2b) to the SGSN and the SGSN relays (in Step 3) the Forward SRNS Context to the target RNC. 
     Upon receiving the GA-PSR-HANDOVER-COMMAND, the UE immediately suspends uplink GTP PDU transfer. It immediately begins accessing the UTRAN using indicated channel access parameters in the message. UE&#39;s access attempt is detected by the Node B and RNC  6310 , and is reported (in Step 4) to the SGSN  6320  via the Relocation Detect message. 
     The UE completes the lower layer setup and configuration, and sends (in Step 5a) the RRC Physical Channel Reconfiguration Complete to the target RNC  6310 . This triggers the RNC  6310  to send (in Step 5b) the Relocation Complete message to SGSN  6320 . At this stage, the target RNC assumes the role of SRNC for the UE. 
     The packet data flow is now (in Step 6) active via the UTRAN. Next, the SGSN releases the Iu_PS connection by sending (in Step 7a) Iu Release Command message to the GANC, to which GANC responds (in Step 7b) with Iu Release Complete message. If the Routing Area of the cell under the target RNC is different from that under the old GANC cell, then the UE  6305  performs (in Step 8) the Routing Area Update procedure. 
     U. Short Message Service 
     GAN provides support for both Circuit Switched and Packet Switched SMS services. GAN-attached UEs will be able to send and receive SMS messages via the GAN. 
     1. CS-Based SMS 
     CS-based SMS support in GAN is based on the same mechanism that is utilized for CS mobility management and call control. On the UE side, the SMS layers (including the supporting CM sub layer functions) utilize the services of the MM layer to transfer SMS messages per standard circuit switched UMTS implementation. 
     The SM-CP protocol is effectively tunneled between the UE and the CN, using GA-CSR UPLINK DIRECT TRANSFER and GA-CSR DOWNLINK DIRECT TRANSFER messages between the UE and the GANC, where the GANC relays the SM-CP messages via RANAP messages for transport over the Iu-cs interface. As with the mobility management and call control procedures, the secure IPSec tunnel and TCP session are used to provide secure and reliable SMS delivery over the IP network. 
     2. PS-Based SMS 
     PS-based SMS message transfer is based on the same mechanism as the transfer of the PS mobility management and session management signaling messages. On the UE side, the SMS layers (including the supporting CM sub layer functions) utilize the services of the GA-PSR layer to transfer SMS messages per standard packet switched UMTS implementation. As with mobility management and session management signaling, the secure IPSec tunnel and TCP session is used to provide secure and reliable PS-based SMS delivery over the IP network. 
     VI. Configuration Information 
     A. GAN UARFCN and Primary Scrambling Code for Handover-to-GAN 
     In some embodiments, selection of the UMTS Absolute Radio Frequency Channel Number (UARFCN) use the following guidelines:
         1. The UARFCN should be allocated from the operator&#39;s assigned UARFCN values.   2. The UARFCN may be desired to be the same unique number across the whole operator network to minimize the RNC configuration effort.   3. The Primary Scrambling Code (possible values from 0 to 511) should not be allocated from the operator&#39;s in-use values; i.e., codes used by macro cells.   4. The Primary Scrambling Code may be desired to be the same unique number across the whole operator network to minimize the RNC configuration effort.       

     Several options are discussed in more detail below. 
     1. Option 1 
     Some embodiments allocate the GAN UARFCN from the DCS band that is being used for GSM. This would result in the DL UARFCNs in the range of 1162 to 1513, inclusive. In this scheme, there are no restrictions in the selection of the specific primary scrambling code (PSC) for GAN—any of the 512 values can be used in the particular UARFCN chosen. 
     Where initial UMTS deployments are in the 1900 MHz band, an analogous approach may be employed—namely the use of UARFCNs from the 850 MHz band. That would give a GAN UARFCN range of 4357 to 4458, inclusive. Alternatively, UARFCNs from a PCS sub-band doing a non-UMTS technology can also be specified. Again, there are no restrictions in the selection of PSC in a given GAN UARFCN. 
     2. Option 2 
     The strategy here is to take advantage of TDD unpaired spectrum and use its UARFCN ranges for GAN purposes. Many operators, as part of the UMTS auction, won a TDD unpaired 5 MHz spectrum, in addition to one or more FDD pairs. The TDD spectrum has remained unused and is likely to remain that way for near foreseeable future. 
     Even if a given operator does not own any TDD spectrum in a given market, any unused TDD spectrum from any operator in the market can be used since it is a completely harmless interference-free procedure for a UE to do a cell search. Even if a given TDD unpaired 5 MHz is in use in UTRAN-TDD mode, an FDD-only handset is likely fail beyond the initial synchronization at PHY layer. Many handsets planned for near foreseeable future are FDD-only. 
     If the handsets semantically allow these values, and these UARFCNs are indeed defined in 3GPP, and the infrastructure vendors do allow provisioning of these UARFCN ranges in their systems, then this approach is feasible. The UARFCN ranges in this case are: 9504 to 9596 and 10054 to 10121. As is the case in Option 1, there are no restrictions in PSC selection of GAN. 
     3. Option 3 
     This plan calls for use of idle FDD spectrum&#39;s UARFCN for GAN purpose. The “idle” spectrum may or may not belong the particular operator. In many parts of Europe and Asia, the FDD spectrums are still unused due to bidders of auction either going out of business or the owners choosing not to deploy services yet due to cost and unavailability of equipment. 
     VII. Identifiers In Gan 
     A. Identifiers for UEs and generic IP access network 
     The key UE and generic IP access network addressing parameters are the IMSI associated with the (U)SIM in the terminal, Public IP Address of the UE, and the generic IP access network point of attachment address (AP-ID). The IMSI associated with the (U)SIM is provided by the UE to the GANC during the Registration procedure. The GANC maintains a record for each registered UE. For example, IMSI is used by the GANC to index the appropriate UE record when the GANC receives a RANAP PAGING message. 
     The Public IP address of UE is the source IP present in the outermost IP header of packets received from the UE by the GANC-SEGW. If available, this identifier may be used by the GANC to support location services and fraud detection or by service providers to signal Managed IP networks IP flows that require special QoS treatment. 
     The generic IP access network point of attachment address (AP-ID) is provided by the UE to the GANC at Registration. The AP-ID may be used by the GANC to support location services or by the service provider to restrict GAN access to authorized APs. 
     B. Service Area Identifiers for GAN 
     1. GAN Service Area for Location Services &amp; Billing 
     Service Area Identifiers (SAI) in UMTS may be used to perform location-basing routing of a call for services such as: emergency services; operators; announcements and freephone numbers. SAI can be also used by the core network to identify the location of where a call was originated/terminated for charging purposes. The GANC provides a SAI to the core network indicating the Iu-mode GAN service area. 
     a) Assigning GAN SAI Based on UTRAN/GERAN Location 
     In the Iu-mode GAN architecture, the UE has a direct IP-based connection to the GANC. The GAN coverage area may overlay the UTRAN/GERAN coverage area. Logical mapping of GAN Cells to a SAI can be completed at various resolutions, for example (but not limited to): (1) a GAN SAI for each UTRAN/GERAN cell, (2) a GAN SAI for each UTRAN/GERAN routing area; or (3) a GAN SAI for each UTRAN/GERAN location area. A single GANC could represent one or more SAI in one or more location areas (LAI). 
     VIII. Alternative Embodiments 
     In some embodiments, instead of using separate CSR and PSR protocols, as described in the previous sections, a single protocol, Generic Access Radio Resource Control (GA-RRC) is used. The following sections describe the architecture and messaging features of this protocol layer. Only the features that are different from the previous embodiments are described. 
     A. Control and User Plane Architecture 
     The Iu interface standards include support for both ATM and IP-based signaling and user data transport mechanisms. 
     1. Circuit Switched (CS) Domain 
     a) CS Domain—Control Plane 
       FIG. 64  illustrates the GAN architecture in support of the CS Domain control plane in some embodiments. The figure shows different protocol layers for the UE  6405 , Generic IP Network  6410 , GANC  6415 , and MSC  6420 .  FIG. 64  also shows the two interfaces Up  6425  and Iu-cs  6430 . The main features of the GAN CS domain control plane architecture are as follows. The underlying Access Layers  6435  and Transport IP layer  6440  provide the generic connectivity between the UE  6405  and the GANC  6415 . The IPSec layer  6445  provides encryption and data integrity between the UE  6405  and GANC  6415 . The Remote IP layer  6450  is the ‘inner’ IP layer for IPSec tunnel mode and is used by the UE  6405  to be addressed by the GANC  6415 . The Remote IP layer  6450  is configured during the IPSec connection establishment. 
     In some embodiments a single TCP connection  6455  is used to provide reliable transport for both the GA-RC  6460  and GA-RRC  6465  signaling between the UE  6405  and GANC  6415 . The TCP connection  6455  is managed by GA-RC  6460  and is transported using the Remote IP layer  6450 . 
     The Generic Access Resource Control (GA-RC) protocol  6460  manages the Up session, including the GAN discovery and registration procedures. The Generic Access Radio Resource Control (GA-RRC) protocol  6465  performs functionality equivalent to the UMTS-RRC protocol, using the underlying connection managed by the GA-RC sublayer  6460 . Note that GA-RRC  6465  includes both CS service and PS service-related signaling messages. The GANC  6415  terminates the GA-RRC protocol  6465  and inter-works it to the RANAP protocol  6470  over the Iu-cs  6430  interface. The NAS protocols, such as MM  6475  and above, are carried transparently between the UE  6405  and MSC  6420 . In some embodiments, the Iu-cs signaling transport layers  6495  are per 3GPP TS 25.412. 
     b) CS Domain—User Plane 
       FIG. 65  illustrates the GAN protocol architecture in support of the CS domain user plane in some embodiments. The figure shows different protocol layers for the UE  6505 , Generic IP Network  6510 , GANC  6515 , and MSC  6520 .  FIG. 65  also shows the two interfaces Up  6525  and Iu-cs  6530 . The main features of the GAN CS domain user plane architecture are as follows. The underlying Access Layers  6535  and Transport IP layer  6540  provide the generic connectivity between the UE  6505  and the GANC  6515 . 
     The IPSec layer  6545  provides encryption and data integrity. CS domain user plane data is transported using the Iu User Plane (Iu UP) protocol  6550  running over RTP/UDP ( 6555  and  6560 ) between UE  6505  and MSC  6520 . Each Iu UP protocol  6550  instance may operate in either transparent or support modes, as described in “UTRAN Iu interface user plane protocols”, 3GPP TS 25.415 standard. The mode choice is indicated to the GANC by the MSC using RANAP and to the UE by the GANC using GA-RRC. Support for the AMR FR codec, as specified in “AMR speech codec; General description”, 3GPP TS 26.071 standard, is mandatory when operating in GAN mode, with support for other codecs being optional. In some embodiments, the Iu-cs data transport layers  6595  are per 3GPP TS 25.414. 
     Some embodiments that utilize GA-RRC protocol implement a protocol stack for the GANC that is different than the protocol stack shown for the GANC  6515 . In these embodiments, the GANC protocol stack is similar to the GANC  1115  protocol stack illustrated in  FIG. 11 . In these embodiments, the GANC has additional protocol layers Remote IP, UDP, and RTP over the IPSec layer  6545 . The GANC also has the additional Iu UP protocol layer over the data transport layers  6595 . Similar to the GANC  1115  shown in  FIG. 11 , the GANC in these embodiments interworks the CS domain user plane between the RTP/UDP and the Iu User Plane protocol. 
     2. Packet Switched (PS) Domain 
     a) PS Domain—Control Plane 
       FIG. 66  illustrates the GAN architecture in support of the PS Domain Control Plane in some embodiments. The figure shows different protocol layers for the UE  6605 , Generic IP Network  6610 , GANC  6615 , and SGSN  6620 .  FIG. 66  also shows the two interfaces Up  6625  and Iu-ps  6630 . The main features of the GAN PS domain control plane architecture are as follows. The functions of GA-RRC  6635  and underlying layers are as described in Sub-section VIII.A.1.a: “CS Domain—Control Plane”, above. The GA-RRC protocol  6635  performs functionality equivalent to the UTRAN RRC protocol, using the underlying Up session managed by the GA-RC  6640 . The GA-RRC  6635  includes both CS service and PS service-related signaling messages. 
     The GANC  6615  terminates the GA-RRC protocol  6635  and inter-works it to the RANAP protocol  6645  over the Iu-ps interface  6630 . NAS protocols, such as for GMM, SM and SMS  6650 , are carried transparently between the UE  6605  and SGSN  6620 . In some embodiments, the Iu-ps signaling transport layers  6695  are per 3GPP TS 25.412. 
     b) PS Domain—User Plane 
       FIG. 67  illustrates the GAN architecture for the PS Domain User Plane in some embodiments. The figure shows different protocol layers for the UE  6705 , Generic IP Network  6710 , GANC  6715 , and SGSN  6720 .  FIG. 67  also shows the two interfaces Up  6725  and Iu-ps  6730 . The main features of the GAN PS domain user plane architecture are as follows. The underlying Access Layers  6735  and Transport IP  6740  layer provides the generic connectivity between the UE  6705  and the GANC  6715 . The IPSec layer  6745  provides encryption and data integrity. The GTP-U  6750  protocol operates between the UE  6705  and the SGSN  6720 , transporting the upper layer payload (i.e., PS domain user plane data  6755 ) across the Up  6725  and Iu-ps interfaces  6730 . User data is carried transparently between the UE  6705  and core network. In some embodiments, the Iu-ps data transport lower layers  6795  are per 3GPP TS 25.414. 
     Some embodiments that utilize GA-RRC protocol implement a protocol stack for the GANC that is different than the protocol stack shown for the GANC  6715 . In these embodiments, the GANC protocol stack is similar to the GANC  1815  protocol stack illustrated in  FIG. 18 . In these embodiments, the GANC has additional protocol layers Remote IP, UDP, and GTP-U over the IPSec layer  6745 . In these embodiments, the GTP-U in the UE and the GTP-U layer over the UDP layer in the GANC is a part of GA-RRC protocol. The GANC also has the additional IP, UDP, and GTP-U layers over the data transport lower layers  6795 . 
     3. GA-RC (Generic Access Resource Control) 
     The GA-RC protocol provides a resource management layer, with the following functions. Discovery and registration with GANC, registration update with GANC, application level keep-alive with GANC, and support for identification of the AP being used for GAN access. 
     a) States of the GA-RC sub-layer 
       FIG. 68  illustrates the GA-RC sublayer in the UE in some embodiments. As shown, the GA-RC sub-layer in the UE can be in one of two states: GA-RC-DEREGISTERED  6805  or GA-RC-REGISTERED  6810 . In the GA-RC-DEREGISTERED state  6805 , the UE may be in a GAN coverage area; however, the UE has not registered successfully with the GANC. The UE may initiate the GAN Registration procedure when in the GA-RC-DEREGISTERED state  6805 . The UE returns to GA-RC-DEREGISTERED state  6805  on loss of TCP or IPSec connection or on execution of the GAN De-registration procedure. 
     In the GA-RC-REGISTERED state  6810 , the UE is registered with the Serving GANC. The UE has an IPSec tunnel and an TCP connection established to the Serving GANC through which the UE may exchange GA-RC or GA-RRC signaling messages with the GANC. While the UE remains in the GA-RC-REGISTERED state  6805  it performs application level keep-alive with the GANC. 
     In the GA-RC-REGISTERED state, the UE may be in either UTRAN/GERAN mode  6815  or GAN mode  6820 . The UE (1) may be camped on GERAN or UTRAN and idle, (2) may be active in GERAN or UTRAN (e.g., a GSM RR or a UTRAN RRC connection may be established), (3) may have “roved in” to GAN mode, or (4) may have recently “roved out” of GAN mode (e.g., due to handover from GAN). 
     4. GA-RRC (Generic Access Radio Resource Control) 
     The GA-RRC protocol provides a resource management layer, which is a replacement for UTRAN-RRC and provides the following functions: (1) setup of transport channels for CS and PS traffic between the UE and GANC, (2) flow control of PS traffic, (3) CS and PS handover support between UTRAN/GERAN and GAN, (4) direct transfer of NAS messages between the UE and the core network, and (5) other functions such as paging and security configuration. 
     a) States of the GA-RRC Sub-layer 
     The GA-RRC sub-layer in the UE can be in two states, GA-RRC-IDLE  6825  or GA-RRC-CONNECTED  6830  as illustrated in  FIG. 68 . The UE enters the GA-RRC-IDLE  6825  state when the UE switches the serving RR entity to GA-RRC and the SAP between the NAS and the GA-RRC is activated. This switch may occur only when the GA-RC is in the GA-RC-REGISTERED state. The UE moves from the GA-RRC-IDLE state  6825  to the GA-RRC-CONNECTED state  6830  when the GA-RRC connection is established and returns to GA-RRC-IDLE state when the GA-RRC connection is released. Upon GA-RRC connection release, an indication that no dedicated resources exist is passed to the upper layers. The UE may also enter the GA-RRC-CONNECTED state while in the GA-RC-REGISTERED state in GERAN/UTRAN mode when Handover to GAN is being performed. In the same way, the UE enters the GA-RC-REGISTERED state in GERAN/UTRAN mode from the GA-RRC-CONNECTED state when Handover from GAN is successfully executed. 
     B. High-Level Procedures 
     1. GA-RRC Connection handling 
     The GA-RRC connection is a logical connection between the UE and the GANC, either for the CS or PS domain. It is established when the upper layers in the UE request GA-RRC to establish a signaling connection and the UE is in idle mode (no RRC connection exists). When a successful response is received from the network, GA-RRC replies to the upper layer that it has entered RRC connected mode. The upper layers have then the possibility to request transmission of NAS messages to the network. 
     a) GA-RRC Connection Establishment 
     i) UE Initiated GA-RRC Connection Establishment 
       FIG. 69  illustrates successful (and unsuccessful) establishment of the GA-RRC Connection when initiated by the UE in some embodiments. The UE  6905  initiates GA-RRC connection establishment by sending (in Step 1) the GA-RRC REQUEST message to the GANC  6910 . This message contains the Establishment Cause indicating the reason for GA-RRC connection establishment. The message also includes the Domain Indicator (CS or PS). GANC  6910  signals the successful response to the UE  6905  by sending (in Step 2) the GA-RRC REQUEST ACCEPT and the UE  6905  enters GA-RRC connected mode. Alternatively, the GANC  6910  may return (in Step 3) a GA-RRC REQUEST REJECT indicating the reject cause. 
     ii) Network Initiated GA-RRC Connection Establishment 
       FIG. 70  illustrates successful establishment of the GA-RRC Connection when initiated by the network in some embodiments. The CN  7015  sends (in Step 1) a RANAP Paging message to the GANC  7010  identified through the last Location Update received by it and includes the TMSI if available. The IMSI of the UE being paged is always included in the request, as is the Domain Indicator (CS or PS). A paging cause may be included. 
     Next, the GANC  7010  identifies the UE registration context using the IMSI provided by the CN  7015 . It then pages (in Step 2) the UE  7005  using the GA-RRC PAGING REQUEST message. The UE  7005  responds (in Step 3) with a GA-RRC INITIAL DIRECT TRANSFER message containing a NAS message appropriate to the Domain Indicator (CS or PS) and cause. Alternatively, the UE  7005  responds (in Step 3) with a GA-RRC PAGING RESPONSE message containing a NAS message, the Domain Indicator (i.e., CS or PS) and cause. The UE  7005  enters GA-RRC connected mode. The GANC  7010  establishes an SCCP connection to the CN  70015 . The GANC  7010  then forwards (in Step 4) the NAS message to the CN  7015  using the RANAP Initial UE Message. Subsequent NAS messages between the UE and core network will be sent between GANC and CN using the RANAP Direct Transfer message. 
     b) GA-RRC Connection Release 
       FIG. 71  shows release of the logical GA-RRC connection between the UE and the GANC in some embodiments. The CN  7115  indicates (in Step 1) to the GANC  7110  to release the user plane connection allocated to the UE  7115 , via the RANAP Iu Release Command message. The GANC  7110  confirms (in Step 2) resource release to CN  7115  using the Tu Release Complete message  7125 . 
     Next, the GANC  7110  commands (in Step 3) the UE  7105  to release resources, using the GA-RRC CONNECTION RELEASE message. The UE  7105  confirms (in Step 4) resource release to the GANC  7110  using the GA-RRC CONNECTION RELEASE COMPLETE message and the GA-RRC state in the UE changes to idle. 
     3. Security Mode Control 
       FIG. 72  illustrates the message flow for security mode control in some embodiments. The CN  7215  sends (in Step 1) the RANAP Security Mode Command message to GANC  7210 . This message contains the integrity key (IK) and allowed algorithms, and optionally the encryption key (CK) and allowed algorithms. The GANC  7210  sends (in Step 2) the GA-RRC SECURITY MODE COMMAND message to the UE  7205 . This message indicates the integrity protection and encryption settings (i.e., that are applicable after relocation to UTRAN), and a random number. The UE  7205  stores the information for possible future use after a handover to UTRAN. 
     Next, the UE  7205  computes a MAC based on the random number, the UE IMSI and the integrity key calculated by the UE. The UE  7205  then sends (in Step 3) the GA-RRC SECURITY MODE COMPLETE message to signal its selected algorithm and the computed MAC. The GANC  7210  then verifies the MAC using the random number, the UE IMSI and the integrity key provided by the CN  7215  in step 1. If the GANC verifies the MAC to be correct it sends (in Step 4) the Security Mode Complete message to the CN  7215 . The MAC proves that the identity that is authenticated to the GANC is the same as the identity authenticated to the core network. 
     4. GA-RRC NAS Signaling Procedures 
     After GA-RRC connection establishment, NAS signaling may be transferred from CN-to-UE and from UE-to-CN. 
     a) CN-to-UE NAS Signalling 
       FIG. 73  illustrates core network to UE NAS signaling of some embodiments. For CN-to-UE NAS signaling, the Core Network  7315  sends (in Step 1) a NAS PDU to the GANC via the RANAP Direct Transfer message. The GANC  7310  encapsulates (in Step 2) the NAS PDU within a GA-RRC DL DIRECT TRANSFER message and forwards the message to the UE  7305  via the existing TCP connection. 
     b) UE-to-CN NAS Signaling 
       FIG. 74  illustrates the UE to core network NAS signaling of some embodiments. The UE  7405  GA-RRC layer receives a request from the NAS layer to transfer an uplink NAS PDU. Since the MM connection (and hence RR signaling connection) already exists, the UE GA-RRC encapsulates the NAS PDU within a GA-RRC UL DIRECT TRANSFER message and sends (in Step 1) the message to the GANC  7410 . The GANC  7410  relays (in Step 2) the received message to the Core Network  7415  via the RANAP Direct Transfer message  7420 . 
     5. Mobile Originated CS Call 
     a) UE Terminate Iu UP packet 
       FIG. 75  illustrates mobile originated CS call procedure in some embodiments. The description of the procedure assumes the UE  7505  is in GAN mode; i.e., it has successfully registered with the GANC  7510  and GA-RRC is the serving RR entity in the UE  7505 . It also assumes that no GA-RRC connection exists between the UE  7505  and GANC  7510  (i.e., GA-RRC-IDLE state). The GA-RRC Connection Establishment procedure is performed (in Step 1) as described in Sub-section VIII.B.1.a.i: UE Initiated GA-RRC Connection Establishment, above. Upon request from the upper layers, the UE  7505  sends (in Step 2) the CM Service Request to the GANC  7510  in the GA-RRC INITIAL DIRECT TRANSFER message. 
     The GANC  7510  establishes an SCCP connection to the CN  7515  and forwards (in Step 3) the CM Service Request to the CN  7515  using the RANAP Initial UE Message. Subsequent NAS messages between the UE  7505  and core network  7515  will be sent between GANC  7510  and CN  7515  using the RANAP Direct Transfer message. 
     The CN  7515  may optionally authenticate (in Step 4) the UE  7505  using standard UTRAN authentication procedures. The CN  7515  may optionally initiate (in Step 5) the Security Mode Control procedure described in Sub-section VIII.B.3: “Security Mode Control”, above. 
     The UE  7505  sends (in Step 6) the Setup message providing details on the call to the CN  7515  and its bearer capability and supported codecs. This message is contained within the GA-RRC UL DIRECT TRANSFER between the UE  7505  and the GANC  7510 . The GANC  7510  forwards (in Step 6) the Setup message to the CN  7515 . 
     The CN  7515  indicates (in Step 7) it has received the call setup and it will accept no additional call-establishment information using the Call Proceeding message to the GANC  7510 . The GANC  7510  forwards (in Step 7) this message to the UE  7505  in the GA-RRC DL DIRECT TRANSFER message. 
     The CN  7515  requests (in Step 8) the GANC  7510  to assign call resources using the RANAP RAB Assignment Request message. The CN  7515  includes the RAB-ID, the CN Transport Layer Address (IP address) and the CN Iu Transport Association (UDP port number) for user data. The GANC  7510  sends (in Step 9) the GA-RRC ACTIVATE CHANNEL message to the UE  7505  including bearer path setup information received in the RAB Assignment Request message such as: (1) Radio Access Bearer (RAB) parameters; e.g., RAB-ID, UDP port &amp; the IP address for the uplink RTP stream and (2) Iu UP parameters (e.g., Iu UP mode, where support mode is used for AMR voice calls). 
     Since Iu UP support mode is indicated, the UE  7505  sends (in Step 10) the Iu UP INITIALISATION packet to the IP address and UDP port indicated in the GA-RRC ACTIVATE CHANNEL message. This message is routed to the core network  7515  (e.g., the R4 media gateway). The core network  7515  responds (in Step 11) with the Iu UP INITIALISATION ACK packet. The core network  7515  sends the message to the source IP address and UDP port number of the received INITIALISATION packet. 
     The UE  7505  sends (in Step 12) the GA-RRC ACTIVATE CHANNEL ACK to the GANC  7510 . The GANC signals (in Step 13) to the CN  7515  that the RAB has been established by sending a RANAP RAB Assignment Response message. The GANC  7510  signals (in Step 14) the completion of the RAB establishment to the UE  7505  with the GA-RRC ACTIVATE CHANNEL COMPLETE message. 
     An end-to-end audio path now exists between the UE  7505  and the CN  7515 . The UE  7505  can now connect the user to the audio path. The CN  7515  signals to the UE  7505 , with the Alerting message, that the called party is ringing. The message is transferred (in Step 15) to the GANC  7510  and GANC forwards (in Step 15) the message to the UE  7505  in the GA-RRC DL DIRECT TRANSFER. 
     When the UE  7505  has not connected the audio path to the user, it generates ring back to the calling party. Otherwise, the network-generated ring back will be returned to the calling party. The CN  7515  signals that the called party has answered, via the Connect message. The message is transferred (in Step 16) to the GANC  7510  and GANC forwards (in Step 16) the message to the UE  7505  in the GA-RRC DL DIRECT TRANSFER  7595 . The UE  7505  connects the user to the audio path. If the UE  7505  is generating ring back, it stops and connects the user to the audio path. 
     The UE  7505  sends (in Step 17) the Connect Ack message in response, and the two parties are connected for the voice call. This message is contained within the GA-RRC UL DIRECT TRANSFER between the UE  7505  and the GANC  7510 . The GANC forwards (in Step 17) the Connect Ack message to the CN  7515 . Bi-directional voice traffic flows (in Step 18) between the UE  7505  and CN  7515  through the GANC  7510 . 
     b) GANC Terminates Iu UP Packet 
     Some embodiments utilize an alternative procedure for the mobile originated CS call using RRC protocol.  FIG. 76  illustrates steps performed during a mobile originated CS call in these embodiments. The procedure assumes that the UE is in GAN mode; i.e., it has successfully registered with the GANC and GA-RRC is the serving RR entity for CS services in the UE. It also assumes that no GA-RRC signaling connection exists between the UE and GANC (i.e., GA-RRC-IDLE state). As shown, the GA-RRC Connection Establishment procedure is performed (in Step 1). In some embodiments, this procedure is performed. Next, the UE  7605  sends the CM Service Request message to the GANC  7610  within the GA-RRC UL DIRECT TRANSFER message. 
     Next, the GANC  7610  establishes an SCCP connection to the core network CN  7615  and forwards (in Step 3) the NAS PDU (i.e., the CM Service Request message) to the core network CN  7615  using the RANAP Initial UE Message. The message includes the Domain Indicator set to value ‘CS domain’. Subsequent NAS messages between the UE and core network CN will be sent between GANC and core network CN using the RANAP Direct Transfer message. 
     The core network CN  7615  may optionally authenticate (in Step 4) the UE using standard UTRAN authentication procedures. The core network CN  7615  may optionally initiate (in Step 5) the Security Mode Control procedure. The UE  7605  sends (in Step 6) the Setup message providing details on the call to the core network CN and its bearer capability and supported codecs. This message is contained within the GA-RRC UL DIRECT TRANSFER between the UE and the GANC. The GANC forwards the Setup message to the core network CN. 
     Next, the core network CN  7615  indicates (in Step 7) it has received the call setup and it will accept no additional call-establishment information using the Call Proceeding message to the GANC. The GANC forwards (in Step 7) this message to the UE in the GA-RRC DL DIRECT TRANSFER message. 
     The core network CN  7615  requests (in Step 8) the GANC  7610  to assign call resources using the RANAP RAB Assignment Request message. The core network CN  7615  includes the RAB-ID, the CN Transport Layer Address and the CN Iu Transport Association for user data, and an indication that Iu UP support mode is required, among other parameters. 
     The GANC  7610  then sends (in Step 9) the GA-RRC ACTIVATE CHANNEL message to the UE  7605  including bearer path setup information such as: (1) Channel mode, (2) Multi-rate codec configuration, (3) UDP port &amp; the IP address for the uplink RTP stream, and (4) 
     Voice sample size. 
     Next, the UE  7605  sends (in Step 10) the GA-RRC ACTIVATE CHANNEL ACK to the GANC  7610  indicating the UDP port for the downlink RTP stream. Since Iu UP support mode is indicated by the core network CN in step 8, the GANC  7610  sends (in Step 11) the Iu UP INITIALIZATION packet to the core network CN. 
     In response, the core network CN responds (in Step 12) with the Iu UP INITIALISATION ACK packet. The GANC  7610  signals (in Step 13) the completion of the RAB establishment to the UE  7605  with the GA-RRC ACTIVATE CHANNEL COMPLETE message. Alternatively, Steps 11 and 12 may occur before Step 9. 
     The GANC  7610  signals to the core network CN  7615  that the RAB has been established by sending (in Step 14) a RANAP RAB Assignment Response message. The core network CN  7615  signals to the UE  3505 , with the Alerting message, that the called party is ringing. The message is transferred (in Step 15) to the GANC  7610  and GANC forwards (in Step 15) the message to the UE  7605  in the GA-RRC DL DIRECT TRANSFER. When the UE has not connected the audio path to the user, it generates ring back to the calling party. Otherwise, the network-generated ring back will be returned to the calling party. 
     Next, the core network CN  7615  signals that the called party has answered, via the Connect message. The message is transferred (in Step 16) to the GANC  7610  and GANC forwards (in Step 16) the message to the UE in the GA-RRC DL DIRECT TRANSFER. The UE connects the user to the audio path. If the UE is generating ring back, it stops and connects the user to the audio path. 
     The UE  7605  then sends (in Step 17) the Connect Ack message in response, and the two parties are connected for the voice call. This message is contained within the GA-RRC UL DIRECT TRANSFER between the UE and the GANC. The GANC forwards the Connect Ack message to the core network CN. At this time, bi-directional voice traffic flows (in Step 18) between the UE  7605  and core network CN  7615  through the GANC  7610 . 
     6. Mobile Terminated CS Call 
       FIG. 77  illustrates mobile terminated CS call procedure in some embodiments. The description of the procedure assumes the UE  7705  is in GAN mode; i.e., it has successfully registered with the GANC  7710  and GA-RRC is the serving RR entity in the UE  7705 . It also assumes that no GA-RRC connection exists between the UE  7705  and GANC  7710  (i.e., GA-RRC-IDLE state). 
     A mobile-terminated call arrives at the CN  7715 . The CN  7715  sends (in Step 1) a RANAP Paging message to the GANC  7710  identified through the last Location Update received by it and includes the TMSI if available. The IMSI of the mobile being paged is always included in the request. The GANC  7710  identifies the UE registration context using the IMSI provided by the CN  7715 . The GANC then pages (in Step 2) the UE  7705  using the GA-RRC PAGING REQUEST message. The message includes the TMSI, when available in the request from the CN  7715 . Otherwise, the message includes only the IMSI of the UE  7705 . 
     The UE  7705  responds (in Step 3) with a GA-RRC INITIAL DIRECT TRANSFER message containing the Paging Response. The UE  7705  enters GA-RRC connected mode. The GANC  7710  establishes an SCCP connection to the CN  7715 . The GANC  7710  then forwards (in Step 4) the paging response to the CN  7715  using the RANAP Initial UE Message. Subsequent NAS messages between the UE  7705  and core network  7715  will be sent between GANC  7710  and CN  7715  using the RANAP Direct Transfer message. 
     The CN  7715  may optionally authenticate (in Step 5) the UE  7705  using standard UTRAN authentication procedures. The CN  7715  may optionally update (in Step 6) the security configuration in the UE  7705 , via the GANC  7710 , as described in Sub-section VIII.B.3: “Security Mode Control”, above. The CN  7715  initiates call setup using the Setup message sent (in Step 7) to the UE  7705  via GANC  7710 . GANC forwards (in Step 7) this message to the UE  7705  in the GA-RRC DL DIRECT TRANSFER message. 
     The UE  7705  responds (in Step 8) with Call Confirmed using the GA-RRC UL DIRECT TRANSFER after checking it&#39;s compatibility with the bearer service requested in the Setup and modifying the bearer service as needed. If the Setup included the signal information element, the UE  7705  alerts the user using the indicated signal, else the UE  7705  alerts the user after the successful configuration of the user plane. The GANC  7710  forwards (in Step 8) the Call Confirmed message to the CN  7715 . The CN  7715  initiates (in Step 9) the assignment procedure with the GANC  7710 , which triggers the setup of the RTP stream (voice bearer channel) between the GANC  7710  and UE  7705 . 
     The UE  7705  signals (in Step 10) that it is alerting the user, via the Alerting message contained in the GA-RRC UL DIRECT TRANSFER. The GANC  7710  forwards (in Step 10) the Alerting message to the CN  7715 . The CN  7715  sends a corresponding alerting message to the calling party. The UE  7705  signals (in Step 11) that the called party has answered, via the Connect message contained in the GA-RRC UL DIRECT TRANSFER. The GANC  7710  forwards (in Step 11) the Connect message to the CN  7715 . The CN  7715  sends a corresponding Connect message to the calling party and through connects the audio. The UE  7705  connects the user to the audio path. 
     The CN  7715  acknowledges (in Step 12) via the Connect Ack message to the GANC  7710 . GANC  7710  forwards (in Step 12) this message to the UE  7705  in the GA-RRC DL DIRECT TRANSFER. The two parties on the call are connected on the audio path. Bi-directional voice traffic flows (in Step 13) between the UE  7705  and CN  7715  through the GANC  7710 . 
     7. CS Call Clearing 
       FIG. 78  illustrates call clearing initiated by the UE in some embodiments. As shown, the UE  7805  sends (in Step 1) the Disconnect message to the CN  7815  to release the call. This message is contained in the GA-RRC UL DIRECT TRANSFER message between UE  7805  and GANC  7810 . The GANC  7810  forwards (in Step 1) the Disconnect message to the CN  7815  (i.e., using the RANAP Direct Transfer message). 
     The CN  7815  responds (in Step 2) with a Release message to the GANC  7810 . The GANC  7810  forwards (in Step 2) this message to the UE  7805  using the GA-RRC DL DIRECT TRANSFER message. 
     The UE  7805  responds (in Step 3) with the Release Complete message. This message is contained within the GA-RRC UL DIRECT TRANSFER message between UE  7805  and GANC  7810 . The GANC  7810  forwards (in Step 3) the Disconnect message to the CN  7815 . The CN  7815  triggers (in Step 4) the release of connection as described in Subsection VIII.B.1.b: “GA-CSR Connection Release”. 
     8. CS Handover 
     a) CS Handover from GERAN to GAN 
     i) UE Terminates Iu UP Packet 
       FIG. 79  illustrates the CS Handover from GERAN to GAN procedure in some embodiments. The description of the GERAN to GAN handover procedure assumes the following: (1) the UE is on an active call on the GERAN; (2) the UE mode selection is GAN-preferred, or if GERAN/UTRAN-preferred, the RxLev from the current serving cell drops below a defined threshold, in some embodiments this threshold can be specified as a fixed value, or provided by the GERAN BSS to the UE in dedicated mode; (3) the UE has successfully registered with a GANC, allowing the UE to obtain GAN system information; and (4) the GERAN provides information on neighboring 3G cells such that one of the cells in the 3G neighbor list matches the 3G cell information associated with the GANC, as provided in the AS-related component of the system information obtained from the GANC. 
     The UE begins to include (in Step 1) GAN cell information in the Measurement Report message to the GERAN. The UE reports the highest signal level for the GAN cell. This is not the actual measured signal level on GAN, rather an artificial value (i.e., RxLev=63), allowing the UE to indicate preference for the GAN. 
     Based on UE measurement reports and other internal algorithms, the GERAN BSC decides to handover to the GAN cell. The BSC  7920  starts the handover preparation by sending (in Step 2) a Handover Required message to the CN  7915 , identifying the target 3G RNC (GANC)  7910 . The CN  7915  requests (in Step 3) the target GANC  7910  to allocate resources for the handover using the Relocation Request message. The UE  7905  is identified by the included IMSI parameter. 
     The GANC  7910  sends (in Step 4) the GA-RRC ACTIVATE CHANNEL message to the UE  7905  including bearer path setup information received in the Relocation Request message, such as: (1) UDP port &amp; the IP address for the uplink RTP stream, (2) Radio Access Bearer (RAB) parameters, and (3) Iu UP parameters (e.g., Iu UP mode, where support mode is used for AMR voice calls). 
     Since Iu UP support mode is indicated, the UE  7905  sends (in Step 5) the Iu UP INITIALISATION packet to the IP address and UDP port indicated in the GA-RRC ACTIVATE CHANNEL message. This message is routed to the core network  7915  (e.g., the R4 media gateway). 
     The core network  7915  responds (in Step 6) with the Iu UP INITIALISATION ACK packet. The core network  7915  sends the message to the source IP address and UDP port number of the received INITIALISATION packet. The UE  7905  sends (in Step 7) the GA-RRC ACTIVATE CHANNEL ACK to the GANC  7910 . The GANC  7910  builds a Handover to UTRAN Command message and sends (in Step 8) it to the CN  7915  through the Relocation Request Acknowledge message. 
     The GANC  7910  signals (in Step 9) the completion of the RAB establishment to the UE  7905  with the GA-RRC ACTIVATE CHANNEL COMPLETE message. An end-to-end audio path now exists between the UE  7905  and the CN  7915 . The CN  7915  forwards (in Step 10) the Handover to UTRAN Command message to the GERAN BSC  7920  in the BSSMAP Handover Command message, completing the handover preparation. 
     The GERAN BSC  7920  sends (in Step 11) the Intersystem to UTRAN Handover Command message, containing the Handover to UTRAN Command message, to the UE to initiate handover to GAN. The UE does not switch its audio path from GERAN to GAN until handover completion (i.e., until it sends the GA-RRC HANDOVER COMPLETE message) to keep the audio interruption short. 
     The UE accesses the GANC  7910  using (in Step 12) the GA-RRC HANDOVER ACCESS message, and provides the entire Intersystem to UTRAN Handover Command message received from GERAN. The GANC  7910  indicates (in Step 13) to the CN  7915  that it has detected the UE, using Relocation Detect message. The CN  7915  can optionally now switch the user plane from the source GERAN to the target GAN. Bi-directional voice traffic is now flowing (in Step 14) between the UE and CN  7915 , via GANC  7910 . 
     The UE transmits (in Step 15) the GA-RRC HANDOVER COMPLETE message to indicate the completion of the handover procedure at its end. It switches the user from the GERAN user plane to the GAN user plane. 
     The target GANC  7910  indicates (in Step 16) the handover is complete, using the Relocation Complete message. If it had not done so before, the CN  7915  now switches the user plane from source GERAN to target GAN. 
     Finally, the CN  7915  tears (in Step 17) down the connection to the source GERAN, using Clear Command message. The source GERAN confirms (in Step 18) the release of GERAN resources allocated for this call, using Clear Complete message. 
     ii) GANC Terminates Iu UP Packet 
       FIG. 80  illustrates an alternative procedure for CS handover from GERAN to GAN in some embodiments. The description of the GERAN to GAN handover procedure assumes the following: (1) the UE is on an active call on the GERAN, (2) the UE mode selection is GAN-preferred, or if GERAN/UTRAN-preferred, the RxLev from the current serving cell drops below a defined threshold. In some embodiments, this threshold can be specified as a fixed value, or provided by the GERAN BSS to the UE in dedicated mode, (3) the UE has successfully registered with a GANC, allowing the UE to obtain GAN system information, and (4) the GERAN provides information on neighboring 3G cells such that one of the cells in the 3G neighbor list matches the 3G cell information associated with the GANC, as provided in the AS-related component of the system information obtained from the GANC. As shown, the UE  8005  begins to include GAN cell information in the Measurement Report message to the GERAN BSC  8015 . The UE  8005  reports the highest signal level for the GAN cell. This is not the actual measured signal level on GAN, rather an artificial value (e.g., RxLev=63), allowing the UE to indicate preference for the GAN. 
     Based on UE measurement reports and other internal algorithms, the GERAN BSC  8015  decides to handover to the GAN cell. The BSC  8015  starts the handover preparation by sending (in Step 2) a Handover Required message to the core network CN ( 8020 ), identifying the target 3G RNC (GANC). 
     The core network CN ( 8020 ) requests (in Step 3) the target GANC  8010  to allocate resources for the handover using the Relocation Request message. The UE is identified by the included IMSI parameter. 
     Since Iu UP support mode is indicated, the GANC  8010  sends (in Step 4) the Iu UP INITIALISATION packet to the core network CN. The core network CN responds (in Step 5) with the Iu UP INITIALISATION ACK packet. 
     The GANC  8010  builds a Handover to UTRAN Command message and sends it (in Step 6) to the core network CN  8020  through the Relocation Request Acknowledge message. The core network CN forwards (in Step 7) the Handover to UTRAN Command message to the GERAN BSC  8015  in the BSSMAP Handover Command message, completing the handover preparation. 
     Next, the GERAN BSC  8015  sends (in Step 8) the Intersystem to UTRAN Handover Command message, containing the Handover to UTRAN Command message, to the UE  8005  to initiate handover to GAN. The UE does not switch its audio path from GERAN to GAN until handover completion (i.e., until it sends the GA-RRC HANDOVER COMPLETE message) to keep the audio interruption short. 
     The UE  8005  accesses (in Step 9) the GANC  8010  using the GA-RRC HANDOVER ACCESS message, and provides the entire Intersystem to UTRAN Handover Command message received from GERAN. The GANC  8010  sends (in Step 10) the GA-RRC ACTIVATE CHANNEL message to the UE  8005  including bearer path setup information such as: (1) Channel mode, (2) Multi-rate codec configuration, (3) UDP port &amp; the IP address for the uplink RTP stream, and (4) Voice sample size. 
     Next, the UE  8005  sends (in Step 11) the GA-RRC ACTIVATE CHANNEL ACK to the GANC  8010  indicating the UDP port for the downlink RTP stream. The GANC  8010  signals (in Step 11) the completion of the RAB establishment to the UE  8005  with the GA-RRC ACTIVATE CHANNEL COMPLETE message. 
     The UE  8005  transmits (in Step 13) the GA-RRC HANDOVER COMPLETE message to indicate the completion of the handover procedure at its end. It switches the user from the GERAN user plane to the GAN user plane. The GANC  8010  indicates (in Step 14) to the core network CN ( 8020 ) that it has detected the UE, using Relocation Detect message. The CN can optionally now switch the user plane from the source GERAN to the target GAN. 
     Bi-directional voice traffic is now (in Step 15) flowing between the UE  8005  and core network CN  8020 , via GANC  8010 . The target GANC  8010  indicates (in Step 16) the handover is complete, using the Relocation Complete message. If it had not done so before, the CN now switches the user plane from source GERAN to target GAN. 
     The CN tears down (in Step 17) the connection to the source GERAN, using Clear Command message. Finally, the source GERAN  8015  confirms (in Step 18) the release of GERAN resources allocated for this call, using Clear Complete message. 
     b) CS Handover from UTRAN to GAN 
     i) UE Terminate Iu UP Packet 
     The description of the UTRAN to GAN Handover procedure assumes the following: (1) the UE is on an active call on the UTRAN; (2) the UE has been ordered by the RNC to make inter-frequency measurements. When the UE is in GAN preferred mode with an Event  2 A configured, the UE handles parameters associated with the Event  2 A in a GAN specific manner (as described in 3GPP TS 25.331) for the reporting of the GAN. When the UE is in GERAN/UTRAN preferred mode and an Event  2 A has been configured for the GAN cell, the UE shall only send a measurement about the GAN cell, when this event is triggered and no UTRAN cells from the neighbour cell list of the UE satisfy the triggering condition of this Event (as described in 3GPP TS 25.331); and (3) the UTRAN provides information on neighbouring cells such that one of the cells in the neighbour list matches the cell associated with the GANC, as provided in the AS-related component of the system information obtained from GANC. 
       FIG. 81  illustrates the CS Handover from UTRAN to GAN procedure in some embodiments. The UE begins to include (in Step 1) information about a GAN cell in the Measurement Report message sent to the RNC  8120 . The UE reports the highest signal level for the GAN cell. This is not the actual measured signal level on the GAN, rather an artificial value allowing the UE to indicate preference for the GAN. 
     Based on UE measurement reports and other internal algorithms, the RNC  8120  decides to initiate handover to the GAN cell. The RNC  8120  starts the preparation phase of the Relocation procedure by sending (in Step 2) a Relocation Required message to the CN  8115 , identifying the target (EGAN) cell. 
     The CN  8115  requests (in Step 3) the target GANC  8110  to allocate resources for the handover using the Relocation Request message. The UE  8105  is identified by the included IMSI parameter. 
     The GANC  8110  sends (in Step 4) the GA-RRC ACTIVATE CHANNEL message to the UE  8105  including bearer path setup information received in the Relocation Request message, such as: (1) UDP port &amp; the IP address for the uplink RTP stream, (2) Radio Access Bearer (RAB) parameters, and (3) Iu UP parameters (e.g., Iu UP mode, where support mode is used for AMR voice calls). 
     Since Iu UP support mode is indicated, the UE  8105  sends (in Step 5) the Iu UP INITIALISATION packet to the IP address and UDP port indicated in the GA-RRC ACTIVATE CHANNEL message. This message is routed to the core network  8115  (e.g., the R4 media gateway). 
     The core network  8115  responds (in Step 6) with the Iu UP INITIALISATION ACK packet. The core network  8115  sends the message to the source IP address and UDP port number of the received INITIALISATION packet. The UE  8105  sends (in Step 7) the GA-RRC ACTIVATE CHANNEL ACK to the GANC  8110 . 
     The target GANC  8110  acknowledges (in Step 8) the handover request message, using Relocation Request Acknowledge message, indicating it can support the requested handover, and including a Physical Channel Reconfiguration message that indicates the radio channel to which the UE  8105  should be directed. 
     The GANC  8110  signals (in Step 9) the completion of the RAB establishment to the UE  8105  with the GA-RRC ACTIVATE CHANNEL COMPLETE message. An end-to-end audio path now exists between the UE  8105  and the CN  8115 . The CN  8115  sends (in Step 10) the Relocation Command message to the RNC  8120 , completing the relocation preparation. 
     The RNC  8120  sends (in Step 11) the PHYSICAL CHANNEL RECONFIGURATION message to the UE to initiate handover to GAN. The UE does not switch its audio path from UTRAN to GAN until handover completion (i.e., until it sends the GA-RRC HANDOVER COMPLETE message) to keep the audio interruption short. The UE accesses (in Step 12) the GANC  8110  using the GA-RRC HANDOVER ACCESS message, and provides the entire PHYSICAL CHANNEL RECONFIGURATION message received from RNC  8120 . 
     The GANC  8110  indicates (in Step 13) to the CN  8115  that it has detected the UE, using Relocation Detect message. The CN  8115  can optionally now switch the user plane from the source RNC  8120  to the target GANC  8110 . Bi-directional voice traffic is now flowing (in Step 14) between the UE and CN  8115 , via GANC  8110 . 
     The UE transmits (in Step 15) the GA-RRC HANDOVER COMPLETE to indicate the completion of the handover procedure from its perspective. It switches the user from the UTRAN user plane to the GAN user plane. The target GANC  8110  indicates (in Step 16) the handover is complete, using the Relocation Complete message. If it has not done so before, the CN  8115  now switches the user plane from source RNC  8120  to target GANC  8110 . 
     Finally, the CN  8115  tears (in Step 17) down the connection to the source RNC  8120 , using Iu Release Command. The source RNC  8120  confirms (in Step 18) the release of UTRAN resources allocated for this call, using Iu Release Complete. 
     ii) GANC Terminates Iu UP Packet 
       FIG. 82  illustrates an alternative procedure for CS handover from UTRAN to GAN using RRC protocol in some embodiments. The description of the UTRAN to GAN Handover procedure assumes the following: (1) the UE is on an active call on the UTRAN, (2) the UE has been ordered by the RNC to make inter-frequency measurements (i.e., if the GAN cell has been allocated a different frequency value than is used in the UTRAN), (a) if the UE is in GAN preferred mode with an Event  2 A configured, the UE handles parameters associated with the Event  2 A in a GAN specific manner for the reporting of the EGAN, (b) when the UE is in GERAN/UTRAN preferred mode and an event  2 A has been configured for the GAN cell, the UE shall only send a measurement about the GAN cell, when this event is triggered and no UTRAN cells from the neighbor cell list of the UE satisfy the triggering condition of this Event (as described in 3GPP TS 25.331), (3) the UTRAN provides information on neighboring cells such that one of the cells in the neighbor list matches the cell associated with the GANC, as provided in the AS-related component of the system information obtained from GANC. 
     As shown in  FIG. 82 , the UE  8205  begins to include information about a GAN cell in the Measurement Report message sent (in Step 1) to the RNC  8215 . The UE  8205  reports the highest signal level for the GAN cell. This is not the actual measured signal level on the GAN, rather an artificial value allowing the UE  8205  to indicate preference for the GAN. 
     Based on UE measurement reports and other internal algorithms, the RNC  8215  decides to initiate handover to the GAN cell. The RNC  8215  starts the preparation phase of the Relocation procedure by sending (in Step 2) a Relocation Required message to the core network CN, identifying the target (GAN) cell. 
     Next, steps 3 to 5 shown in  FIG. 82  are performed similar to steps 3-5 for CSR GERAN to GAN Handover “GANC Terminates Iu UP Packets” Sub-section described above, except that the messages are RRC messages (instead of CSR). The target GANC  8210  acknowledges (in Step 6) the handover request message, using Relocation Request Acknowledge message, indicating it can support the requested handover, and including a Physical Channel Reconfiguration message that indicates the radio channel to which the UE should be directed. 
     Next, the core network CN  8220  sends (in Step 7) the Relocation Command message to the RNC  8215 , completing the relocation preparation. The RNC  8215  sends (in Step 8) the PHYSICAL CHANNEL RECONFIGURATION message to the UE  8205  to initiate handover to GAN. The UE does not switch its audio path from UTRAN to GAN until handover completion (i.e., until it sends the GA-RRC HANDOVER COMPLETE message) to keep the audio interruption short. 
     Next, Steps 9-16 shown in  FIG. 82  are performed similar to Steps 9-16 for CSR GERAN to GAN Handover in “GANC Terminates Iu UP Packets” Sub-section described above, except that Steps 9-16 in  FIG. 82  utilize RRC protocol instead of CSR protocol. Next, the core network CN  8220  tears down (in Step 17) the connection to the source RNC, using Iu Release Command. Finally, the source RNC  8215  confirms (in Step 18) the release of UTRAN resources allocated for this call, using Iu Release Complete. 
     c) CS Handover from GAN to GERAN 
     The procedure description in this sub-clause assumes the following: (1) the UE is on an active call on the EGAN; and (2) the GERAN becomes available and (i) the UE mode selection is GERAN/UTRAN-preferred, or (ii) the UE mode selection is GAN-preferred and the UE begins to leave GAN coverage, based on its local measurements, received RTCP reports, as well as any uplink quality indications received from the GANC. 
     The handover from GAN to GERAN procedure is always triggered by the UE. 
       FIG. 83  illustrates the CS handover from GAN to GERAN procedure in some embodiments. The GANC  8310  may send (in Step 1) a GA-RRC UPLINK QUALITY INDICATION if there is a problem with the uplink quality for the ongoing call. Uplink Quality Indication is information sent by the GANC  8310  to the UE  8305  indicating the crossing of an uplink quality threshold in the uplink direction. Whenever the UE  8305  receives an indication of bad quality, it should start the handover procedure, as described in the next step. Alternatively, UE  8305  can use its local measurements or received RTCP reports, to decide to initiate the handover procedure. 
     The UE  8305  sends (in Step 2) the GA-RRC HANDOVER INFORMATION message to the GANC  8310  indicating the Channel Mode and a list of target GERAN cells, identified by CGI, in order of preference (e.g. ranked by C 1  path loss parameter) for handover, and includes the received signal strength for each identified GERAN cell. This list is the most recent information available from the GSM RR subsystem. In addition, the GA-RRC HANDOVER INFORMATION message may include a list of target UTRAN cells ranked in order of preference for handover, and the received signal strength for each identified UTRAN cell. 
     If the Serving GANC  8310  selects a target GERAN cell, the handover to GERAN procedure is performed. The Serving GANC  8310  starts the handover preparation by signaling (in Step 3) to the CN  8315  the need for handover, using Relocation Required, and including the GERAN cell list provided by the UE  8305 . The GANC  8310  may include only a subset of the cell list provided by the UE  8305 . 
     The CN  8315  selects a target GERAN cell and requests (in Step 4) it to allocate the necessary resources, using Handover Request. The target GERAN builds a Handover Command message providing information on the channel allocated and sends (in Step 5) it to the CN  8315  through the Handover Request Acknowledge message. 
     The CN  8315  signals (in Step 6) the GANC  8310  to handover the UE  8305  to the GERAN, using Relocation Command message, ending the handover preparation phase. GANC  8310  transmits (in Step 7) the GA-RRC HANDOVER COMMAND to the UE  8305  including the details sent by the GERAN on the target resource allocation. The UE  8305  transmits (in Step 8) the Um: Handover Access containing the handover reference element to allow the target GERAN to correlate this handover access with the Handover Command message transmitted earlier to the CN  8315  in response to the Handover Required. 
     The target GERAN confirms (in Step 9) the detection of the handover to the CN  8315 , using the Handover Detect message. The CN  8315  may at this point switch (in Step 10) the user plane to the target BSS. The GERAN provides (in Step 11) Physical Information to the UE  8305  (i.e., Timing Advance) to allow the UE  8305  to synchronize with the GERAN. The UE  8305  signals (in Step 12) to the GERAN that the handover is completed, using Handover Complete. 
     The GERAN confirms (in Step 13) to the CN  8315  the completion of the handover, via Handover Complete message. The CN  8315  may use the target CGI used in the Handover procedure for charging purposes. Bi-directional voice traffic is now flowing (in Step 14) between the UE  8305  and CN  8315 , via the GERAN. 
     On receiving the confirmation of the completion of the handover, the CN  8315  indicates (in Step 15) to the GANC  8310  to release any resources allocated to the UE  8305 , via the Iu Release Command. GANC  8310  commands (in Step 16) the UE  8305  to release resources, using the GA-RRC RELEASE message. GANC  8310  confirms (in Step 17) resource release to CN  8315  using the Iu Release Complete message. 
     The UE  8305  confirms (in Step 18) resource release to the GANC  8310  using the GA-RRC RELEASE COMPLETE message. The UE  8305  may finally deregister (in Step 19) from the GANC  8310 , using GA-RC DEREGISTER message. 
     d) CS Handover from GAN to UTRAN 
     The procedure description in this sub-clause assumes the following: (1) the UE is on an active call on the GAN; (2) the UE is capable of operating in all of the GAN, GERAN and UTRAN modes; and (3) the UTRAN becomes available and (i) the UE is in GERAN/UTRAN-preferred mode, or (ii) the UE mode selection is GAN preferred and begins to leave GAN coverage, based on its local measurements, received RTCP reports, as well as any uplink quality indications received from the GANC. 
       FIG. 84  illustrates the CS handover from GAN to UTRAN procedure in some embodiments. The handover from GAN procedure is always triggered by the UE  8405 . The GANC  8410  may send (in Step 1) a GA-RRC UPLINK QUALITY INDICATION if there is a problem with the uplink quality for the ongoing call. Uplink Quality Indication is information sent by the GANC  8410  to the UE  8405  indicating the crossing of an uplink quality threshold in the uplink direction. Whenever the UE  8405  receives an indication of bad quality, it should start the handover procedure, as described in the next step. Alternatively, UE  8405  can use its local measurements or received RTCP reports, to decide to initiate the handover procedure. 
     The UE  8405  sends (in Step 2) the GA-RRC HANDOVER INFORMATION message to the Serving GANC  8410  indicating the Channel Mode and a list of candidate target UTRAN and GERAN cells, in order of preference for handover, and includes the received signal strength for each identified cell. The UTRAN cells are identified by the PLMN ID, the LAC and the 3G Cell identity (defined in 3GPP TS 25.331). 
     If the Serving GANC  8410  selects UTRAN as the target RAT, the handover to UTRAN procedure is performed. The Serving GANC  8410  starts the handover preparation by signaling (in Step 3) to the CN  8415  the need for handover, using Relocation Required and including the UTRAN cell list provided by the UE  8405 . The GANC  8410  may include only a subset of the cell list provided by the UE  8405 . 
     The CN  8415  starts the handover procedure towards the target RNC  8420  identified by the Serving GANC  8410 . The CN  8415  requests (in Step 4) from the target RNC  8420  to allocate the necessary resources using Relocation Request. The target RNC  8420  builds a Physical Channel Reconfiguration message providing information on the allocated UTRAN resources and sends (in Step 5) it to the CN  8415  through the Relocation Request Acknowledge message. 
     The CN  8415  signals (in Step 6) the Serving GANC  8410  to handover the UE  8405  to the UTRAN, using Relocation Command message (which includes the Physical Channel Reconfiguration message), ending the handover preparation phase. The Serving GANC  8410  transmits (in Step 7) the GA-RRC HANDOVER COMMAND to the UE  8405  including the details sent by the UTRAN on the target resource allocation. 
     Target RNS achieves (in Step 8) uplink synchronization on the Uu interface. The target RNC  8420  confirms (in Step 9) the detection of the handover to the CN  8415 , using the Relocation Detect message. The CN  8415  may at this point switch (in Step 10) the user plane to the target RNS. The UE  8405  signals (in Step 11) to the UTRAN that the handover is completed, using Handover to UTRAN Complete. 
     The UTRAN confirms (in Step 12) to the CN  8415  the completion of the handover, via Relocation Complete message. If the user plane has not been switched in Step 10, the CN  8415  switches the user plane to the target RNS. Bi-directional voice traffic is now flowing (in Step 13) between the UE  8405  and CN  8415 , via the UTRAN. 
     On receiving the confirmation of the completion of the handover, the CN  8415  indicates (in Step 14) to the Serving GANC  8410  to release any resources allocated to the UE  8405 , via the Iu Release Command. The Serving GANC  8410  commands (in Step 15) the UE  8405  to release resources, using the GA-RRC RELEASE message. 
     The Serving GANC  8410  confirms (in Step 16) resource release to CN  8415  using the Iu Release Complete message. The UE  8405  confirms (in Step 17) resource release to the Serving GANC  8410  using the GA-RRC RELEASE COMPLETE message. The UE  8405  may finally deregister (in Step 18) from the Serving GANC  8410 , using GA-RC DEREGISTER message. 
     9. GA-RRC Packet Transport Channel Management Procedures 
     The GA-RRC Packet Transport Channel (GA-RRC PTC) provides the association between the UE and the network for the transport of GPRS user data over the Up interface (i.e., via the GAN in Iu-mode). The PTC uses the GTP-U protocol running over UDP transport. The endpoint addresses of the PTC are identified by the IP addresses and UDP ports assigned to the PTC in the UE and network during the PTC activation procedure. The UDP port number for GTP-U is as defined in 3GPP TS 25.414. Multiple PTC instances between a UE and the network may be activated at the same time, using the same endpoint addresses. Each PTC instance is assigned unique GTP-U Tunnel Endpoint IDs (one on the UE and one on the network) during the activation procedure. The UE and GANC manage the activation and deactivation of the PTC instances based on the requests for data transfer and the configurable PTC Timer. 
     a) States of the GA-RRC Packet Transport Channel 
     The UE in the GA-RRC-CONNECTED state can be in one of two PTC substates: PTC-STANDBY or PTC-ACTIVE. PTC-STANDBY: this is the initial/default PTC substate of the UE when in the GA-RRC-CONNECTED state in GAN mode. The UE is not able to send or receive GPRS user data to or from the network. The UE needs to activate the PTC before sending any GPRS user data. When the UE successfully establishes a PTC, the UE transitions to the PTC-ACTIVE substate. PTC-ACTIVE the UE is in the GA-RRC-CONNECTED state and the PTC is active between the UE and the network and the UE is able to send and receive GPRS user data to and from the network. The following are the possible triggers for GA-RRC PTC activation on the UE side: (1) The UE initiates the uplink user data transfer, and (2) the GANC initiates PTC activation; i.e., the UE receives a GA-RRC-ACTIVATE-PTC-REQUEST message from the GANC. 
     On successful PTC activation and in parallel with transition to the PTC-ACTIVE substate, the UE starts the PTC Timer. When the PTC Timer expires, the UE sends a message to the GANC to initiate PTC deactivation. On successful PTC deactivation, the UE transitions to PTC-STANDBY substate. At any time while in the GA-RRC-CONNECTED state and the PTC-ACTIVE substate, the UE may receive the GA-RRC RELEASE message. In addition to requesting release of the RRC session, this is interpreted by the UE as an implicit PTC deactivate command. At any time while in GAN mode, if the serving RR entity is switched to GSM-RR/UTRAN-RRC, the GA-RRC is disconnected from the GPRS SAPs and the UE enters GERAN/UTRAN mode. Simultaneously, the UE will release the associated PTC regardless of the PTC Timer status. The UE GA-RRC entity maintains one PTC for each active PDP context. The PTC Timer is restarted whenever any uplink user data packet is sent or downlink user data packet is received related to the PDP context. The PTC Timer value is provided to the UE as part of the GAN Registration procedure (i.e., in the GA-RC REGISTER ACCEPT message). 
     b) PTC Initial Activation 
       FIG. 85  illustrates the Packet Transport Channel initial activation procedure of some embodiments. The following description assumes the UE  8505  is in the GA-RRC-IDLE state, in some embodiments. The GA-RRC Connection Establishment procedure is performed (in Step 1) as described in clause UE Initiated GA-RRC Connection Establishment, above. The UE  8505  transitions to the GA-RRC-CONNECTED state and the PTC-STANDBY substate. Additional PS signaling procedures are performed (in Step 2). 
     The CN  8510  (SGSN) initiates (in Step 3) the RAB Assignment procedure and includes the RAB-ID, the CN Transport Layer Address (IP address) and the CN Iu Transport Association (GTP-U Terminal Endpoint Identifier, TEID) for user data. The GANC  8515  sends (in Step 4) the GA-RRC ACTIVATE PTC REQUEST message to the UE  8505  to request activation of the Packet Transport Channel. The message includes the RAB-ID, and the CN IP Address and TEID to allow the UE  8505  to send PTC packets (i.e., GTP-U messages) directly to the SGSN. 
     The UE  8505  acknowledges (in Step 5) the PTC activation and provides the Transport Layer Address (IP address) and Iu Transport Association (GTP-U TEID) that identifies the UE end of the PTC. The UE  8505  transitions to the PTC-ACTIVE substate and starts the PTC Timer. 
     Upon receiving the acknowledgment, the GANC  8515  sends (in Step 6) the RAB Assignment Response message to the CN  8510  (SGSN) to complete the RAB Assignment procedure and includes UE IP Address and GTP-U TEID. Additional PS signalling procedures are performed (in Step 7); examples are illustrated in PDP Context Activation and Network Requested PDP Context Activation Sub-sections, below. The UE  8505  initiates (in Step 8) uplink user data transfer via the established PTC and the CN  8510  (SGSN) may use the same transport channel to send downlink user data packets. 
     c) PTC Data Transfer 
       FIG. 86  illustrates the transfer of GPRS user data packets via the GAN Packet Transport Channel in some embodiments. If required, the GAN PTC is established (in Step 1) as specified in Sub-section VIII.B.9.b: “PTC Initial Activation”, above. Upon the GA-RRC PTC establishment, the UE  8605  enters the PTC-ACTIVE substate and starts the PTC Timer. The UE  8605  initiates (in Step 2) the transfer of an uplink user data packet using the standard GTP-U protocol as specified in 3GPP TS 29.060 and restarts the PTC Timer. 
     The CN  8615  (SGSN) transfers (in Step 3) downlink user data packet utilizing the same PTC associated with the specific PDP context. Downlink user data packets are transferred using the standard GTP-U protocol as specified in 3GPP TS 29.060. Upon receiving the downlink data packet, the UE restarts the associated PTC Timer. Additional uplink and downlink user data packets are transferred (in Step 4) via the same PTC as described in steps 2 and 3, respectively. After each transmission/reception, the UE  8605  restarts the PTC Timer. 
     d) UE Initiated PTC Deactivation 
       FIG. 87  illustrates the scenario when the UE deactivates the Packet Transport Channel after the PTC Timer expires in some embodiments. The UE  8705  is (in Step 1) in the GA-RRC-CONNECTED state and the PTC-ACTIVE substate. The PTC Timer associated with one of the active packet transport channels expires. 
     The UE  8705  sends (in Step 2) the GA-RRC DEACTIVATE PTC REQUEST message to the GANC  8710 , including the RAB-ID to identify the PTC and indicating the normal release as a cause for deactivation. The GANC  8710  sends (in Step 3) a RAB Release Request message to the CN (SGSN)  8715  to request the release of the associated RAB. The CN (SGSN)  8715  responds (in Step 4) with the RAB Assignment Request indicating release. 
     The GANC  8710  responds (in Step 5) to the UE  8705  with a GA-RRC DEACTIVATE PTC ACK message to acknowledge successful deactivation. The UE  8705  transitions to the PTC-STANDBY substate. The GANC  8710  sends (in Step 6) the RAB Assignment Response message to notify the SGSN  8715  that the RAB Release procedure is complete. 
     e) UE Initiated PTC Re-activation 
       FIG. 88  illustrates the scenario when the UE initiates re-activation of the Packet Transport Channel in some embodiments. The UE is in the GA-RRC-CONNECTED and PMM-CONNECTED states; e.g., a PS signaling connection and active PDP context exists between the UE  8805  and CN  8815  but the PTC was previously deactivated by the UE  8805  due to PTC Timer expiry in some embodiments. The UE  8805  is in the GA-RRC-CONNECTED state and the PTC-STANDBY substate. The UE  8805  is in the PMM-CONNECTED state (i.e., a PS signaling connection and an active PDP context exists). 
     The UE  8805  has a PDU to send. The UE  8805  sends (in Step 1) the Service Request message (with Service type value “Data”) to the GANC  8810  in the GA-RRC UL DIRECT TRANSFER message. The GANC  8810  forwards (in Step 2) the Service Request over the existing signaling connection to the CN  8815  using the RANAP Direct Transfer message. 
     The CN  8815  may optionally initiate (in Step 3) the Security Mode Control procedure described in Sub-section VIII.B.3: “Security Mode Control”, above. The CN  8815  responds (in Step 4) with a Service Accept message. The GANC  8810  forwards (in Step 5) the message to the UE  8805 . 
     The UE  8805 , GANC  8810  and CN  8815  establish (in Step 6) the GA-RRC Packet Transport Channel (PTC) as described in steps 3-6 in VIII.B.9.b: “PTC Initial Activation”, above. The UE  8805  transitions to the PTC-ACTIVE substate and starts the PTC Timer. The UE  8805  sends (in Step 7) the uplink PDU. Additional data transfer may take place. 
     f) Network Initiated PTC De-activation 
       FIG. 89  illustrates the scenario when the network initiates de-activation of the Packet Transport Channel in some embodiments. The UE  8905  is in the GA-RRC-CONNECTED state and the PTC-ACTIVE substate. 
     Optionally, the GANC  8910  may initiate the PTC de-activation procedure; e.g., as a result of an error handling procedure. If so, the GANC  8910  sends (in Step 1) the RAB Release Request message to the CN  8915 . The CN (SGSN)  8915  sends (in Step 2) a RAB Assignment Request to request the release of the associated RAB. The release request may include one or more RABs. 
     The GANC  8910  requests (in Step 3) deactivation of the associated GA-RRC PTC by sending the GA-RRC DEACTIVATE PTC REQUEST message to the UE  8905 . The UE  8905  transitions to the PTC-STANDBY substate, stops the PTC Timer and sends (in Step 4) the acknowledgment back to the GANC  8910 . Steps 3 and 4 are repeated for each additional RAB/PTC that needs to be released. The GANC  8910  notifies (in Step 5) the CN (SGSN)  8915  that the release was successful. 
     g) Network Initiated PTC Re-activation 
       FIG. 90  illustrates the scenario when the network initiates re-activation of the Packet Transport Channel in some embodiments. The UE  9005  is in the GA-RRC-CONNECTED and PMM-CONNECTED states; e.g., a PS signaling connection and active PDP context exists between the UE and CN but the PTC was previously deactivated in some embodiments. The UE  9005  is in the GA-RRC-CONNECTED state and the PTC-STANDBY substate. The UE  9005  is in the PMM-CONNECTED state (i.e., a PS signaling connection and an active PDP context exists). 
     The CN  9015  has a PDU to send to send to the UE  9005 . The CN  9015  may optionally initiate (in Step 1) the Security Mode Control procedure described in Sub-section VIII.B.3: “Security Mode Control”, above. The UE  9005 , GANC  9010  and CN  9015  establish (in Step 2) the GA-RRC Packet Transport Channel (PTC) as described in steps 3-6 in clause in Sub-section VIII.B.9.b: “PTC Initial Activation”, above. The UE  9005  transitions to the PTC-ACTIVE substate and starts the PTC Timer. The CN  9015  sends (in Step 3) the downlink PDU. Additional data transfer may take place. 
     h) Implicit PTC De-activation Due to UE De-registration 
       FIG. 96  illustrates the procedure for implicit PTC de-activation in some embodiments. As part of the GAN de-registration procedure, the GANC needs to release all resources allocated to that UE  9605 . GAN de-registration may be initiated either explicitly by the UE  9605  or implicitly by the GANC  9610  if the loss of the signaling connection is detected. Initially, one or more GA-RRC PTCs associated with a UE  9605  are in the PTC-ACTIVE state. 
     The GAN de-registration procedure is initiated (in Step 1) for the UE  9605  either by the UE  9605  or GANC  9610 . Optionally, any outstanding resources associated with the CS Domain are released (in Step 2). Optionally, if there are any outstanding resources associated with the PS Domain, the GANC  9610  initiates (in Step 3) the Iu release procedure to release the corresponding RABs. The CN (SGSN)  9615  responds (in Step 4) with Iu Release Command. Upon receiving the Iu Release Command, the GANC  9610  locally deactivates (in Step 5) all associated PTCs and responds (in Step 6) to the core network (SGSN)  9615  with an Iu Release Complete message. 
     10. PDP Context Activation 
       FIG. 91  illustrates the successful UE-initiated PDP Context Activation procedure, assuming the UE is in GA-RRC-IDLE mode in some embodiments. The GA-RRC Connection Establishment procedure is performed (in Step 1) as described in Sub-section UE Initiated GA-RRC Connection Establishment, above. If a GA-RRC connection already exists (e.g., there is an existing CS call in progress), this step is skipped. 
     Upon request from the upper layers, the UE  9105  sends (in Step 2) the Service Request message (with Service type value “Signaling”) to the GANC  9110  in the GA-RRC INITIAL DIRECT TRANSFER message. The GANC  9110  establishes an SCCP connection to the CN  9115  and forwards (in Step 3) the Service Request to the CN  9115  using the RANAP Initial UE Message. Subsequent NAS messages between the UE  9105  and core network  9115  will be sent between GANC  9110  and CN  9115  using the RANAP Direct Transfer message. 
     The CN  9115  may optionally authenticate (in Step 4) the UE  9105  using standard UTRAN authentication procedures. The CN  9115  may optionally initiate (in Step 5) the Security Mode Control procedure described in Sub-section VIII.B.3: “Security Mode Control”, above. 
     The CN (SGSN)  9115  responds (in Step 6) with a Service Accept message. The GANC  9110  forwards (in Step 6) the message to the UE  9105 . The UE  9105  sends (in Step 7) the Activate PDP Context Request message providing details on the PDP context to the CN  9115 . This message is contained within the GA-RRC UL DIRECT TRANSFER between the UE  9105  and the GANC  9110 . The GANC  9110  forwards (in Step 7) the Activate PDP Context Request message to the CN  9115 . 
     The UE  9105 , GANC  9110  and CN  9115  establish (in Step 8) the GA-RRC Packet Transport Channel (PTC) as described in steps 3-6 in Sub-section VIII.B.9.b: “PTC Initial Activation”, above. The CN  9115  indicates (in Step 9) the PDP context establishment is complete using the Activate PDP Context Accept message to the GANC  9110 . GANC forwards (in Step 9) this message to the UE  9105  in the GA-RRC DL DIRECT TRANSFER message. The UE  9105  and CN  9115  exchange (in Step 10) user data transfer via the established PTC. 
     11. Network Requested PDP Context Activation 
       FIG. 92  illustrates the successful Network-Requested PDP Context Activation procedure, assuming the UE is in GA-RRC-IDLE mode, in some embodiments. Initially, the CN (SGSN)  9215  received downlink user data to transfer to the UE and the associated RAB is not established. The UE is in PMM-IDLE state. 
     The CN (SGSN)  9215  sends (in Step 1) the RANAP Paging message to the UE  9205  via the GANC  9210  to locate the user. The paging request indicates paging for PS Domain signaling. The GANC  9210  forwards (in Step 2) the paging information to the UE  9205  in the GA-RRC PAGING REQUEST message. 
     The UE  9205  responds (in Step 3) to the SGSN  9215  via the GANC  9210  with a Service Request message (with Service type value “Paging response”). The message is encapsulated within the GA-RRC INITIAL DIRECT TRANSFER message. The GANC  9210  forwards (in Step 4) the Service Request message to the SGSN  9215  encapsulated in the RANAP Initial UE Message. 
     The CN  9215  may optionally authenticate (in Step 5) the UE  9205  using standard UTRAN authentication procedures. The CN  9215  may optionally initiate (in Step 6) the Security Mode Control procedure described in Sub-section VIII.B.3: “Security Mode Control”, above. 
     The CN  9215  sends (in Step 7) the Request PDP Context Activation message to the GANC  9210 . The GANC  9210  forwards (in Step 7) this message to the UE  9205  in the GA-RRC DL DIRECT TRANSFER message. 
     The UE  9205  sends (in Step 8) the Activate PDP Context Request message providing details on the PDP context to the CN  9215 . This message is contained within the GA-RRC UL DIRECT TRANSFER between the UE  9205  and the GANC  9210 . The GANC forwards (in Step 8) the Activate PDP Context Request message to the CN  9215 . The UE  9205 , GANC  9210  and CN  9215  establish (in Step 9) the GA-RRC Packet Transport Channel (PTC) as described in steps 3-6 in Sub-section VIII.B.9.b: “PTC Initial Activation”, above. 
     The CN  9215  indicates (in Step 10) the PDP context establishment is complete using the Activate PDP Context Accept message to the GANC  9210 . GANC forwards (in Step 10) this message to the UE  9205  in the GA-RRC DL DIRECT TRANSFER message. The UE  9205  and CN  9215  exchange (in Step 11) user data transfer via the established PTC. 
     12. PDP Context Activation with Active CS Session 
       FIG. 93  illustrates the successful UE-initiated PDP Context Activation procedure, assuming the UE  9305  is in GA-RRC-CONNECTED mode (e.g., existing CS session) in some embodiments. The GA-RRC Connection Establishment procedure is performed as described in Sub-section UE Initiated GA-RRC Connection Establishment, above. If a GA-RRC connection already exists (e.g., there is an existing CS call in progress), this step is skipped. 
     Upon request from the upper layers, the UE  9305  sends (in Step 1) the Service Request message (with Service type value “Signaling”) to the GANC  9310  in the GA-RRC INITIAL DIRECT TRANSFER message. The GANC  9310  establishes (in Step 2) an SCCP connection to the CN  9315  and forwards the Service Request to the CN using the RANAP Initial UE Message. Subsequent NAS messages between the UE  9305  and core network  9315  will be sent between GANC  9310  and CN  9315  using the RANAP Direct Transfer message. 
     The CN  9315  may optionally authenticate (in Step 3) the UE  9305  using standard UTRAN authentication procedures. The CN  9315  may optionally initiate (in Step 4) the Security Mode Control procedure described in Sub-section VIII.B.3: “Security Mode Control”, above. 
     The CN (SGSN)  9315  responds (in Step 5) with a Service Accept message. The GANC  9310  forwards (in Step 5) the message to the UE  9305 . The UE  9305  sends (in Step 6) the Activate PDP Context Request message providing details on the PDP context to the CN  9315 . This message is contained within the GA-RRC UL DIRECT TRANSFER between the UE  9305  and the GANC  9310 . The GANC forwards (in Step 6) the Activate PDP Context Request message to the CN  9315 . 
     The UE  9305 , GANC  9310  and CN  9315  establish (in Step 7) the GA-RRC Packet Transport Channel (PTC) as described in steps 3-6 in Sub-section VIII.B.9.b: “PTC Initial Activation”, above. The CN  9315  indicates (in Step 8) the PDP context establishment is complete using the Activate PDP Context Accept message to the GANC  9310 . GANC forwards (in Step 8) this message to the UE  9305  in the GA-RRC DL DIRECT TRANSFER message. The UE  9305  and CN  9315  exchange (in Step 9) user data transfer via the established PTC. 
     13. SRNS Relocation 
     Serving RNS Relocation Procedure is performed for an UE in PMM-CONNECTED state to move the RAN connection point from old RNC to the new RNC. Two scenarios will be considered: (1) SRNS Relocation from RNC to GANC; i.e from UTRAN to GAN, and (2) SRNS Relocation from GANC to RNC; i.e., from GAN to UTRAN. These procedures include several options based on the support for Iur interface and lossless SRNS Relocation. It is assumed in this version of the GAN Specification that the Iur interface is not supported. Additionally, given that PDCP protocol is not included in the GAN solution in order to optimize the data transport, it is assumed that the lossless SRNS Relocation is not supported either. 
     a) SRNS Relocation from UTRAN to GAN 
       FIG. 94  illustrates SRNS relocation procedure from UTRAN to GAN for a UE that is in PMM Connected state in some embodiments. It is assumed that Iur interface and lossless SRNS relocation procedure are not supported. Initially, the UE  9405  is registered for GAN service and in PMM Connected state. At least one PDP context is active with maximum bitrate higher than 0. 
     After detecting GAN coverage and successfully registering for GAN service, the UE  9405  sends (in Step 1) measurement report to the RNC  9410  indicating the highest signal level for the GAN cell. The RNC  9410  sends (in Step 2) Relocation Required message to the core network (SGSN)  9420  to initiate the SRNS relocation procedure. The message indicates the GANC  9415  as a target RNC  9410  and includes the information necessary for the relocation coordination. 
     The core network (SGSN)  9420  forwards (in Step 3) the request to the GANC  9415 . The message includes the list of the RABs that need to be setup and associated information. Based on the Relocation Request message, the CN  9420  and GANC  9415  establish (in Step 4) requested RABs and associated PS Transport Channels as specified in GA-RRC Packet Transport Channel Management Procedures Sub-section, above. 
     The GANC  9415  responds (in Step 5) to the core network  9420  with acknowledgment including Target RNC  9410  to Source RNC Transport Container. The core network (SGSN)  9420  proceeds (in Step 6) with relocation by sending a Relocation Command to the old RNC that includes the Target RNC to Source RNC Transport Container. 
     The RNC  9410  starts forwarding (in Step 7) of data to the UE  9405  for the RABs that are subject to forwarding. The forwarding is performed for downlink user data only and is based on the Transport Layer Address and Iu Transport Association received from the GANC  9415 . 
     The RNC  9410  sends (in Step 8) the PHYSICAL CHANNEL RECONFIGURATION message to the UE  9405  to initiate relocation to GAN. The RNC  9410  continues with relocation by forwarding (in Step 9) the SRNS Context information to the GANC  9415  via the core network (SGSN)  9420 . The core network (SGNS)  9420  forwards (in Step 10) the SRNS Context to the GANC  9415 . The GANC  9415  responds (in Step 11) with a Relocation Detect message. 
     The UE  9405  sends (in Step 12) a GA-RRC Relocation Complete message to the GANC  9415  to indicate successful relocation. The GANC  9415  sends (in Step 13) the Relocation Complete message to the core network (SGSN)  9420  to complete the procedure. 
     Upon receiving the Relocation Complete message, the core network (SGSN)  9420  switches user plane from RNC  9410  to GANC (UE) and initiates (in Step 14) Iu Release procedure towards the RNC  9410 . After the data forwarding timer expires and after releasing the associated resources, the RNC  9410  responds (in Step 15) with Iu Release Complete message to the core network (SGSN)  9420 . 
     14. Short Message Service 
     GAN provides support for both Circuit Switched and Packet Switched SMS services. GAN-attached and GPRS enabled UEs will be able to send and receive SMS messages via the GAN. 
     a) CS-Based SMS 
     CS-based SMS support in GAN is based on the same mechanism that is utilized for CS mobility management and call control. On the UE side, the SMS layers (including the supporting CM sub layer functions) utilize the services of the MM layer to transfer SMS messages per standard circuit switched UMTS implementation. The SM-CP protocol is effectively tunneled between the UE and the CN, using GA-RRC messages from the UE to the GANC, where the GANC relays the SM-CP to RANAP messages for transport over the Iu-cs interface. As with the mobility management and call control procedures, the secure IPSec tunnel and TCP session are used to provide secure and reliable SMS delivery over the IP network. 
     b) PS-Based SMS 
     PS-based SMS message transfer is based on the same mechanism as the transfer of the PS mobility management and session management signaling messages. On the UE side, the SMS layers (including the supporting CM sub layer functions) utilize the services of the RRC (i.e., GA-RRC) layer to transfer SMS messages per standard packet switched UMTS implementation. As with mobility management and session management signaling, the secure IPsec tunnel and TCP session is used to provide secure and reliable PS-based SMS delivery over the IP network. 
     IX. Computer System 
       FIG. 95  conceptually illustrates a computer system with which some embodiments of the invention are implemented. The computer system  9500  includes a bus  9505 , a processor  9510 , a system memory  9515 , a read-only memory  9520 , a permanent storage device  9525 , input devices  9530 , and output devices  9535 . 
     The bus  9505  collectively represents all system, peripheral, and chipset buses that support communication among internal devices of the computer system  9500 . For instance, the bus  9505  communicatively connects the processor  9510  with the read-only memory  9520 , the system memory  9515 , and the permanent storage device  9525 . 
     From these various memory units, the processor  9510  retrieves instructions to execute and data to process in order to execute the processes of the invention. In some embodiments the processor comprises a Field Programmable Gate Array (FPGA), an ASIC, or various other electronic components for executing instructions. The read-only-memory (ROM)  9520  stores static data and instructions that are needed by the processor  9510  and other modules of the computer system. The permanent storage device  9525 , on the other hand, is a read-and-write memory device. This device is a non-volatile memory unit that stores instruction and data even when the computer system  9500  is off. Some embodiments of the invention use a mass-storage device (such as a magnetic or optical disk and its corresponding disk drive) as the permanent storage device  9525 . Some embodiments use one or more removable storage devices (flash memory card or memory stick) as the permanent storage device. 
     Like the permanent storage device  9525 , the system memory  9515  is a read-and-write memory device. However, unlike storage device  9525 , the system memory is a volatile read-and-write memory, such as a random access memory. The system memory stores some of the instructions and data that the processor needs at runtime. 
     Instructions and/or data needed to perform processes of some embodiments are stored in the system memory  9515 , the permanent storage device  9525 , the read-only memory  9520 , or any combination of the three. For example, the various memory units contain instructions for processing multimedia items in accordance with some embodiments. From these various memory units, the processor  9510  retrieves instructions to execute and data to process in order to execute the processes of some embodiments. 
     The bus  9505  also connects to the input and output devices  9530  and  9535 . The input devices enable the user to communicate information and select commands to the computer system. The input devices  9530  include alphanumeric keyboards and cursor-controllers. The output devices  9535  display images generated by the computer system. The output devices include printers and display devices, such as cathode ray tubes (CRT) or liquid crystal displays (LCD). Finally, as shown in  FIG. 95 , bus  9505  also couples computer  9500  to a network  9565  through a network adapter (not shown). In this manner, the computer can be a part of a network of computers (such as a local area network (“LAN”), a wide area network (“WAN”), or an Intranet) or a network of networks (such as the Internet). 
     It should be recognized by one of ordinary skill in the art that any or all of the components of computer system  9500  may be used in conjunction with the invention. For instance, some or all components of the computer system described with regards to  FIG. 95  comprise some embodiments of the UE, FAP, GANC, and other equipments described above. Moreover, one of ordinary skill in the art will appreciate that any other system configuration may also be used in conjunction with the invention or components of the invention. 
     X. Definitions and Abbreviations 
     The following is a list of definitions and abbreviations used: 
     
       
         
           
               
               
             
               
                   
               
             
            
               
                 AAA 
                 Authentication, Authorization and Accounting 
               
               
                 AKA 
                 Authentication and Key Agreement 
               
               
                 AP 
                 Access Point 
               
               
                 AS 
                 Access Stratum 
               
               
                 BSC 
                 Base Station Controller 
               
               
                 BSS 
                 Base Station Subsystem 
               
               
                 BSSGP  
                 Base Station System GPRS Protocol 
               
               
                 BSSMAP 
                 Base Station System Management Application Part 
               
               
                 CC 
                 Call Control 
               
               
                 CGI 
                 Cell Global Identification 
               
               
                 CM 
                 Connection Management 
               
               
                 CN 
                 Core Network 
               
               
                 CS 
                 Circuit Switched 
               
               
                 CTM 
                 Cellular Text Telephone Modem 
               
               
                 DNS 
                 Domain Name System 
               
               
                 DTM 
                 Dual Transfer Mode 
               
               
                 EAP 
                 Extensible Authentication Protocol 
               
               
                 GA-CSR 
                 Generic Access - Circuit Switched Resources 
               
               
                 GA-PSR 
                 Generic Access - Packet Switched Resources 
               
               
                 GA-RC  
                 Generic Access - Resource Control 
               
               
                 GAN 
                 Generic Access Network 
               
               
                 GANC 
                 Generic Access Network Controller 
               
               
                 ETSI 
                 European Telecommunications Standards Institute 
               
               
                 FCC 
                 US Federal Communications Commission 
               
               
                 FQDN 
                 Fully Qualified Domain Name 
               
               
                 GAD 
                 Geographical Area Description 
               
               
                 GERAN  
                 GSM EDGE Radio Access Network 
               
               
                 GGSN 
                 Gateway GPRS Support Node 
               
               
                 GMM/SM 
                 GPRS Mobility Management and Session Management 
               
               
                 GPRS 
                 General Packet Radio Service 
               
               
                 GSM 
                 Global System for Mobile communications 
               
               
                 GSN 
                 GPRS Support Node 
               
               
                 HLR 
                 Home Location Register 
               
               
                 HPLMN  
                 Home PLMN 
               
               
                 IETF 
                 Internet Engineering Task Force 
               
               
                 IKE 
                 Internet Key Exchange 
               
               
                 IKEv2  
                 IKE Version 2 
               
               
                 IMEISV 
                 International Mobile station Equipment Identity and  
               
               
                   
                 Software Version number 
               
               
                 IMSI 
                 International Mobile Subscriber Identity 
               
               
                 IP 
                 Internet Protocol 
               
               
                 LA 
                 Location Area 
               
               
                 LAI 
                 Location Area Identity 
               
               
                 LLC 
                 Logical Link Control 
               
               
                 MAC 
                 Medium Access Control 
               
               
                 MAC 
                 Message Authentication Code 
               
               
                 MM 
                 Mobility Management 
               
               
                 MS 
                 Mobile Station 
               
               
                 MSC 
                 Mobile Switching Center 
               
               
                 MTP1  
                 Message Transfer Part layer 1 
               
               
                 MTP2 
                 Message Transfer Part layer 2 
               
               
                 MTP3 
                 Message Transfer Part layer 3 
               
               
                 NAS 
                 Non-Access Stratum 
               
               
                 PDP 
                 Packet Data Protocol 
               
               
                 PDU 
                 Protocol Data Unit 
               
               
                 PLMN 
                 Public Land Mobile Network 
               
               
                 PSAP 
                 Public Safety Answering Point - A PSAP is an  
               
               
                   
                 emergency services network element 
               
               
                   
                 that is responsible for answering emergency calls 
               
               
                 PSTN 
                 Public Switched Telephone Network 
               
               
                 P-TMSI 
                 Packet - TMSI 
               
               
                 QoS 
                 Quality of Service 
               
               
                 RA 
                 Routing Area 
               
               
                 RAC 
                 Routing Area Code 
               
               
                 RAI 
                 Routing Area Identity 
               
               
                 RAT 
                 Radio Access Technology 
               
               
                 RLC 
                 Radio Link Control 
               
               
                 RNC 
                 Radio Network Controller 
               
               
                 RNS 
                 Radio Network Subsystem 
               
               
                 RTCP 
                 Real Time Control Protocol 
               
               
                 RTP 
                 Real Time Protocol 
               
               
                 SCCP 
                 Signaling Connection Control Part 
               
               
                 SEGW  
                 SEcurity GateWay 
               
               
                 SGSN  
                 Serving GPRS Support Node 
               
               
                 SIM 
                 Subscriber Identity Module 
               
               
                 SMLC  
                 Serving Mobile Location Center 
               
               
                 SMS 
                 Short Message Service 
               
               
                 SNDCP 
                 Sub-Network Dependent Convergence Protocol 
               
               
                 TBF 
                 Temporary Block Flow 
               
               
                 TC 
                 Transport Channel 
               
               
                 TCP 
                 Transmission Control Protocol 
               
               
                 TFO 
                 Tandem Free Operation 
               
               
                 TMSI  
                 Temporary Mobile Subscriber Identity 
               
               
                 TrFO  
                 Transcoder Free Operation 
               
               
                 TTY 
                 Text Telephone or TeletYpewriter 
               
               
                 UE 
                 User Equipment 
               
               
                 UDP 
                 User Datagram Protocol 
               
               
                 UMTS  
                 Universal Mobile Telecommunication System 
               
               
                 UTRAN 
                 UMTS terrestrial Radio Access Network 
               
               
                 Up 
                 Up is the Interface between UE and GANC 
               
               
                 VLR 
                 Visited Location Register 
               
               
                 VPLMN 
                 Visited Public Land Mobile Network 
               
               
                   
               
            
           
         
       
     
     While the invention has been described with reference to numerous specific details, one of ordinary skill in the art will recognize that the invention can be embodied in other specific forms without departing from the spirit of the invention. For instance the specific sequencing of procedures described and their associated attributes may be modified. Thus, one of ordinary skill in the art would understand that the invention is not to be limited by the foregoing illustrative details, but rather is to be defined by the appended claims.