Patent Publication Number: US-2005117540-A1

Title: Method and apparatus for routing messages in a network

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application is related to application entitled “APPARATUS AND METHOD FOR SHARED NETWORK,” Motorola case number CS23736RL, filed on even date herewith and commonly assigned to the assignee of the present application and which is hereby incorporated by reference.  
      This application is also related to application entitled “METHOD FOR SELECTING A CORE NETWORK,” Motorola case number CS23737RL, filed on even date herewith and commonly assigned to the assignee of the present application and which is hereby incorporated by reference.  
      This application is also related to application entitled “WIRELESS ACCESS NETWORK SHARING AMONG CORE NETWORKS AND METHODS,” Motorola case number CS23738RL, filed on even date herewith and commonly assigned to the assignee of the present application and which is hereby incorporated by reference.  
     BACKGROUND  
      1. Field  
      The present disclosure is directed to a method and an apparatus for routing messages in a network and more particularly to routing a message to a desired core network.  
      2. Description of Related Art  
      Presently, wireless communication systems in general include a radio access network (RAN) and a core network (CN). The access independent part of a network is known as the core network. In some mobile communication networks, the core network includes a mobile switching center, a packet data network and other network entities. In other types of networks, similar network entities are present and perform similar tasks such as routing calls, packet sessions, etc. User equipment, also known as mobile stations (MS) in the case of wireless networks, access the network through the access dependent part of the network, known as access network (AN). In one type of wireless communication networks using radio frequency (RF) signals, the AN is known as the radio access network (RAN). The RAN includes a radio network controller (RNC) or base station controller (BSC) and base stations or Node Bs. The RAN manages the wireless communication links between the base stations and the mobile stations. The CN receives messages from the public switched telephone network (PSTN), other mobile stations, and other core networks and core network entities and passes them to the mobile stations through the RAN.  
      In current networks, the RAN and the CN are configured such that one radio access network is connected to only one core network. This means that the RAN and the CN are able to use the same network identity or public land mobile network (PLMN) identity, where the PLMN identity is broadcast by the RAN and identifies the network, both the radio access network and the core network. The mobile station therefore only needs to select the RAN and a separate selection of the CN operator is unnecessary.  
      Emerging wireless communication technologies allow network operators to share resources. One example of network sharing is to share the radio access network resources by allowing multiple core networks operated typically by different service providers or operators to couple to the radio access network. The RAN is connected to the multiple core networks by a radio network controller (RNC). The radio network controller controls the radio resources, such as the base stations. This allows multiple service providers to use one radio access network and the same limited number of frequency bands. However, the system cannot accommodate multiple system operators to ensure that certain information from a MS is directed to the proper core network, system operator, or service provider. In the emerging universal mobile telephone system (UMTS), the routing of messages is either to a packet switched domain or circuit switched domain and not by system operator. Multiple service provider routing, or routing to the appropriate core network is not possible as there is only one system operator for both the radio network and the core network. In a shared RAN, multiple core network operators share the radio infrastructure and/or radio frequencies and thus messages must be routed to the proper core network as the RAN is now associated with multiple core network operators.  
      Thus, there is a need for a method of message routing where a plurality of core networks controlled by different operators is coupled to a single access network. This access network may be a radio access network or any other access network.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The embodiments of the present disclosure will be described with reference to the following example figures, wherein like numerals designate like elements, and wherein:  
       FIG. 1  is an exemplary diagram of a wireless communication system of the present disclosure according to one embodiment;  
       FIG. 2  is an exemplary circuit block diagram of the present disclosure according to one embodiment;  
       FIG. 3  is an exemplary flow chart illustrating messages routing of the present disclosure according to one embodiment;  
       FIG. 4  is an exemplary flow chart illustrating messages routing of the present disclosure according to another embodiment;  
       FIG. 5  is an exemplary flow chart illustrating messages routing of the present disclosure according to another embodiment; and  
       FIG. 6  is an exemplary diagram of messages of the present disclosure according to one embodiment. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is an exemplary diagram of a wireless communication system  100  according to the present disclosure. The system  100  includes a radio network controller (RNC)  102 , at least one base station  104 , and a mobile station (MS)  105 . The radio network controller  102  may also be a base station controller (BSC) which is coupled to at least one transceiver such as a base station  104  or wireless access point or the like. The RNC  102  and the base stations  104  form the radio access network (RAN)  106  portion of the system. Multiple core networks are connected to the radio access network  106 . A first core network, which is coupled to the RAN  106 , includes a mobile switching center (MSC), and a serving GPRS support node (SGSN). The core network (CN)  108  portion of the system, illustrated in  FIG. 1 , includes a first MSC  110  and a first SGSN  112  for a first service provider. A second core network includes a second MSC  114  and a second SGSN  116  for a second service provider. The core network  108  can also include other MSC&#39;s  120  and other SGSN&#39;s  112 . It is understood by one skilled in the art that any number of core networks may be coupled to a RAN  106 . In addition it should be noted that a wireless local area network can also form the radio access network, in which case a wireless local area network access point takes the place of the base station in the radio access network. It should also be noted that the system  100  is not limited to wireless communication and that the system  100  may be a land-based communication system. The SGSN  112  may also be a packet data network or the like.  
      Although the embodiment illustrated in  FIG. 1  shows a universal mobile telephone system (UMTS) network, the present disclosure may apply to other wireless communication systems such as code division multiple access (CDMA) systems, i.e. IS-95 related and cdma2000, global standard for mobile communication (GSM) and other time division multiple access systems, wireless local area networks (WLAN) systems or the like.  
      Mobile stations accessing the network through other wireless access networks such as through WLAN would use the WLAN access point similar to the RAN. WLAN currently operates under the 802.11 standards also known as WiFi but the access points are not limited to this technology. In this exemplary embodiment, the WLAN is coupled to multiple core networks. It can be a dedicated connection or through the internet or a combination of other connections. The WLAN broadcasts the service set identifier (SSID) instead of a PLMNid. The SSID identifies an individual WLAN access point and the MS  105  will register to the core network(s) that the WLAN is connected to. The MS  105  will either receive a registration accept message or receive a list of sharing networks in the registration reject message or similar negotiation procedure. The list of allowed SSID may be something stored in the terminal or in the SIM or USIM or similar such application.  
      In  FIG. 1 , the MS  105  first attempts to form a communication link with at least one of the base stations  104  of the RAN  106 . The MS  105  in the exemplary embodiment is also configured to operate with at least one of the core network operators, typically the service provider from which the subscriber purchased the service. In current mobile networks, a MS  105  is programmed to tune to a certain predetermined frequency or set of frequencies. The core network operator, or service provider, through the RNC  102  and each base station  104 , transmits a core network identifier or a public land mobile network identity (PLMNid) that identifies the core network. The PLMNid may include at least a mobile country code and a mobile network code. The core network identifier may identify the service provider associated with the core network. The MS  105  also has a list of PLMN identities (PLMNid&#39;s) of one or more preferred core network operators stored either in the MS  105  or on a SIM card (not shown) coupled to the MS  105 . When the MS  105  receives a signal having the same PLMNid that matches a PLMNid that is stored in the MS memory or SIM, the MS  105  attempts to connect to or register with the core network associated with the selected PLMNid. When the MS  105  finds a signal on a frequency with a PLMNid that is not stored in the MS  105  or SIM, it may attempt to connect to or register with the core network associated with that PLMNid. The MS  105  of the present disclosure may or may not have stored a matching PLMNid of that being broadcast by the RAN  106  and the MS  105  will attempt to register on the network identified by the PLMNid broadcast by the RAN  106 .  
       FIG. 2  is an exemplary block diagram of a MS  105 , such as a UMTS terminal, according to one exemplary embodiment. The MS  105  may include a housing  210 , a controller  220  coupled to the housing  210 , audio input and output circuitry  230  coupled to the housing  210 , a display  240  coupled to the housing  210 , a transceiver  250  coupled to the housing  210 , a user interface  260  coupled to the housing  210 , and a memory  270  coupled to the housing  210 . A signal message module  280  can be coupled to the controller  220 . The signal message module  280  may be hardware coupled to the controller  220  or software located in the memory  270  and executed by the controller  220 . The memory  270  can include a core network operator ID or the list of core network operator identifiers may be stored in a subscriber identity module (SIM)  290  or Universal Subscriber Identity Module (USIM).  
      Continuing with  FIG. 2 , the display  240  can be a liquid crystal display (LCD), a light emitting diode (LED) display, a plasma display, or any other means for displaying information. The transceiver  250  may include a transmitter and/or a receiver. The audio input and output circuitry  230  can include a microphone, a speaker, a transducer, or any other audio input and output circuitry. The user interface  260  can include a keypad, buttons, a touch pad, a joystick, an additional display, or any other device useful for providing an interface between a user and an electronic device. The memory  270  may include a random access memory, a read only memory, an optical memory, a SIM, or any other memory that can be coupled to a mobile communication device.  
      In one exemplary embodiment shown in  FIG. 3 , an exemplary flow diagram illustrates the message routing method of the present disclosure. The MS  105  receives a system information broadcast message  302 . Upon receiving the system information broadcast message, the MS  105  requests  304  a radio connection. In one exemplary embodiment, the radio connection is requested by the MS  105  transmitting a radio connection request message. Next the MS  105  receives a grant of the radio connection  306  by the RNC  102 . A radio connection or communication link has been established between the MS  105  and the base station  104 . Establishing a connection between a MS  105  and a base station  104  is known to those skilled in the art and can be achieved in multiple fashions.  
      Next the MS  105  will use the established communication link or connection to attempt to register with a core network  108 . The MS  105  transmits  308  a signaling connection establishment message over the radio connection. The signaling connection establishment message may include a desired core network operator identifier. In response to the transmission of the signaling connection establishment message  308 , the MS  105  will receive a registration accept message  310  over the radio connection. This message may include an assigned core network operator identifier. In response to the MS  105  receiving the registration accept message  310 , the MS  105  will transmit a signaling message that includes the desired core network operator identifier, the assigned core network operator identifier or an equivalent thereof. This includes all subsequent messages to the registered core network, or non-access stratum (NAS) messages  312 , all including either the desired core network operator identifier, the assigned core network operator identifier or an equivalent thereof.  
      In one embodiment, the desired core network operator identifier is a desired PLMNid and the assigned core network operator identifier is an assigned PLMNid. One equivalent of the core network identifier may also be a coded identifier that is equivalent to the desired core network operator identifier or the assigned core network operator identifier that is smaller in size.  
      In one exemplary embodiment, the MS  105  transmits the desired core network identifier in the signaling connection establishment message to the RNC  102 . In response, the MS  105  will receive the registration accept message  310  without an assigned core network operator identifier. The MS  105  will then transmit all subsequent NAS messages with the desired core network operator identifier.  
      In another exemplary embodiment, the MS  105  transmits the desired core network identifier in the signaling connection establishment message to the RNC  102 . In response, the MS  105  will receive the registration accept message  310  with an assigned core network operator identifier. The MS  105  will then transmit all subsequent NAS messages  312  with the assigned core network operator identifier. The assigned core network operator identification may be the same as the as the desired core network operator identification.  
      In yet another exemplary embodiment, the MS  105  transmits the signaling connection establishment message  308  without the desired core network identifier to the RNC  102 . In response, the MS  105  will receive the registration accept message  310  with an assigned core network operator identifier. The MS  105  will then transmit all subsequent NAS messages  312  with the assigned core network operator identifier. For example the MS  105  is a roaming mobile such that it does not recognize PLMN identifiers broadcast by the RAN and therefore may be assigned by the network to any of the core networks coupled with the RAN.  
      It is not necessary that the core networks be coupled to wireless networks such as the RAN. The network may be a wired network such as wireline, cable, or the like. Wireline devices such as home phones may access any of the many wireline operators who are all sharing the wire connection to the home.  
      Moving to  FIG. 4 , a flow diagram is shown outlining the message routing at the RNC 102 . In the first step, the RNC  102  transmits a system information broadcast message  402 . Once a MS  105  receives and responds to the system information broadcast message, the RNC  102  receives a radio connection request  404 . Next the RNC  102  transmits a grant of the radio connection  406  to the MS  105 . A radio connection or communication link has been established between the MS  105  and the RNC  102  through the base station  104 .  
      When the MS  105  attempts to register with a core network  108 , the RNC  102  will receive a signaling connection establishment message  408  over the radio connection from the MS  105 . The signaling connection establishment message may include a desired core network operator identifier as discussed above. In response to receiving the signaling connection establishment message  408 , the RNC  102  will transmit a registration accept message  410 , that may be received from the registration accepting core network, over the radio connection. This message may include an assigned core network operator identifier. The RNC  102  will then receive all subsequent messages to the registered core network, or non-access stratum (NAS) messages  412  which include either the desired core network operator identifier, the assigned core network operator identifier or an equivalent thereof. The RNC  102  uses the included information to route the message to the identified core network.  
      The MS  105  will transmit the signaling connection establishment message either with, or without a desired core network operator identifier. In an exemplary embodiment where the desired core network operator identifier is transmitted, the signaling connection establishment message is then routed to the desired core network by a router. The router is either in the RNC  102  and a part of the RNC  102  functionality or a separate node, which is a part of the network. For example, the router is coupled to the RNC  102  or in between the RNC  102  and the multiple core networks.  FIG. 5  illustrates the routing of the signaling connection establishment message received from the MS  105 . In one exemplary embodiment the RNC  102  receives  502  the signaling connection establishment message. The RNC  102  determines that the signaling connection establishment message includes a desired core network operator identifier  504 . If the signaling connection establishment message does include the desired core network operator identifier, the RNC  102  then determines  506  if the desired core network operator identifier is to be the assigned core network operator identifier. If the desired core network operator identifier is to be the assigned core network operator identifier, then the RNC  102  sends  508  the signaling connection establishment message to the identified core network.  
      If the desired core network operator identifier is determined  504  not to be the assigned core network operator identifier, then the RNC  102  routes the signaling connection establishment message to the core network identified by the assigned core network operator identifier. The assigned core network operator identifier may be generated by a PLMN allocation function. The PLMN allocation function generates  510  a core network operator identifier in accordance with predetermined criteria determined by the network operators or service providers. The RNC  102  sends  512  the signaling connection establishment message to the core network associated with the PLMNid assigned and generated  510  by the allocation function.  
      In another exemplary embodiment, the RNC  102  receives the signaling connection establishment message and determines  504  that the signaling connection establishment message does not include a desired core network operator identifier. Then the RNC  102  executes a PLMN or core network allocation function to generate  510  and assign a PLMNid associated with a core network operator identifier. The RNC  102  will then send  512  the assigned core network operator identifier determined by the PLMN allocation function to the core network identified by the assigned core network operator identifier. The use of the RNC  102  to route the signaling connection establishment message is one example. The route determination can be determined in a separate module aside from the RNC  102  or other parts of either the RAN  106  or CN  108 .  
      In this embodiment, the RNC  102 , or RNC equivalent, which is connected to a plurality of core networks, and will select which core network to send the registration request message to with the allocation function. The allocation function, which may reside in the RNC  102 , may assign the PLMNid based on predetermined settings, by randomly selecting the core network to receive the registration request or the RNC may select the core network in a round robin manner or by the indicated domain identity such as the packet domain or circuit switched domain.  
      In one exemplary embodiment both the desired core network operator identifier or the assigned core network operator identifier can be correlated to a PLMN code. The PLMN code correlates to a unique PLMN identity. In one exemplary embodiment the PLMN code is shorter than the complete PLMN identifier, for example the desired core network operator identifier or the assigned core network operator identifier. This code can be assigned by the RNC  102  or the core network that is accepting the registration. In one embodiment, the PLMN code is assigned within the registration accept message. In another embodiment the PLMN code is assigned by the network when forwarding the registration accept message to the MS  105 .  
       FIG. 6  illustrates code or message segments of the present disclosure. The communications device communicates with the core network through signaling messages. In one exemplary embodiment, the signaling message is carried in a direct transfer message. In particular  FIG. 6  illustrates a direct transfer message (DTM)  602 . This direct transfer message is an signaling message that may be an uplink DTM or a downlink DTM. The DTM  602  may include a PLMNid  604 , a CN domain identity  606  and a NAS message  608 . The PLMNid  604  includes the core network operator identifier. The CN identity  606  in one embodiment identifies whether the NAS message is a message directed towards the circuit switched domain or a packet switched domain. The PLMNid may also be a PLMN code, which is representative of the PLMNid. In one embodiment the PLMN code is shorter than the PLMNid.  
      In one exemplary embodiment, the DTM  610  includes the desired core network operator identifier  612 . This may be a desired PLMNid in one exemplary embodiment. In this embodiment, the MS  102  can send the DTM  610  with the desired core network operator identifier as discussed above. The RNC  102  can then send a DTM  614  with an assigned PLMNid  618  or an assigned core network operator identifier, in the registration accept message, for example.  
      Referring back to  FIG. 1 , a MS  105  may register on different core network operators to obtain service on the different core network domains. For example, a first core network may be capable of packet switched services and second core network may be capable of circuit switched services. The MS  105  may therefore send packet switched information to the first core network and the circuit switched information to the second core network. This may be achieved by including the appropriate PLMNid or PLMN code in the DTM along with the CN domain identity which identifies either the circuit switched or packet switched network.  
      While this invention has been described with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. For example, various components of the embodiments may be interchanged, added, or substituted in the other embodiments. Accordingly, the preferred embodiments of the invention as set forth herein are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the invention.