Abstract:
IMS nodes and a satellite radio access node (RAN) are described herein which are operative to establish certain calls (e.g., voice calls) with reduced latency and selectively using a High Penetration Alert (HPA) page to reach a terminating satellite user equipment (UE).

Description:
CLAIM OF PRIORITY 
     This application claims the benefit U.S. Provisional Application Ser. No. 61/644,190 filed on May 8, 2012. The contents of this document are incorporated by reference herein. 
     RELATED PATENT APPLICATION 
     This application is related to co-assigned U.S. Publication No. 2011/0075655 A1 which is entitled “Method to Optimize Call Establishment in Mobile Satellite Communication System”. The contents of this document are incorporated by reference herein. 
    
    
     TECHNICAL FIELD 
     The present invention relates generally to telecommunication systems, and in particular to IMS nodes and a satellite RAN which are operative to establish certain calls (e.g., voice calls) with reduced latency and selectively using a High Penetration Alert (HPA) page to reach a terminating satellite UE. 
     BACKGROUND 
     The following abbreviations are herewith defined, at least some of which are referred to within the following description of the prior art and the present invention. 
     3GPP Third Generation Partnership Project 
     AAA Authentication, Authorization and Accounting, Diameter AA-Answer 
     AAR Diameter AA-Request 
     ARP Allocation Retention Priority 
     AS Application Server 
     AVP Attribute-Value Pair 
     CCA Credit-Control-Answer 
     CCR Credit-Control-Request 
     CSCF Call Session Control Function 
     Cx Name for interface between CSCF and HSS 
     DHCP Dynamic Host Configuration Protocol 
     DNS Domain Name System 
     ENUM Electronic Numbering 
     HLR Home Location Register 
     HPA High Penetration Alert 
     H-PLMN Home-Public Land Mobile Network 
     HSS Home Subscriber Server 
     IETF Internet Engineering Task Force 
     iFC initial Filter Criteria 
     IP-CAN IP Connectivity Access Network 
     IMS IP Multimedia Subsystem 
     ISC Name of interface between S-CSCF and HSS 
     MGCF Media Gateway Controller Function 
     MGW Media Gateway 
     MRFC Media Resource Function Controller 
     MRFP Media Resource Function Processor 
     NRSPCA Network Initiated Secondary PDP Context 
     PCC Policy and Charging Control 
     P-CSCF Proxy CSCF (see CSCF) 
     PCRF Policy and Charging Rule Function 
     PSTN Public Switched Telephony Network 
     RAA Diameter Re-Auth-Answer 
     RAB Radio Access Bearer 
     RADIUS Remote Authentication Dial-In User Service 
     RAR Diameter Re-Auth-Request 
     RTP Real-Time Transport Protocol 
     Rx Name of interface between AF/AS and PCRF 
     S-CSCF Serving CSCF (see CSCF) 
     SGW Signaling Gateway 
     Sh Name of interface between AS and HSS 
     SIP Session Initiation Protocol 
     UE User Equipment 
     URI Universal Resource Indicator 
     V-PLMN Visited-Public Land Mobile Network 
     WCDMA Wide Band Code Division Multiple Access 
     The IP Multimedia Subsystem (IMS), as defined by the 3 rd  Generation Partnership Project (3GPP) standards body, merges telephony and Internet technology by providing an all-IP based architecture for the telecommunications industry. The IMS is based on the Session Initiation Protocol (SIP) and makes heavy use of the protocols defined within the IETF. IMS offers a network of servers and databases that assist a user agent with the task of establishing and managing sessions. IMS uses the term sessions because the connections between users are no longer limited to voice services (a phone call). Sessions may be voice, video, text, or other services connecting two or more user agents together. A representative IMS network is depicted in  FIG. 1  (PRIOR ART). 
     Communications between nodes within an IMS network utilize the Session Initiation Protocol (SIP). SIP is a signaling protocol for Internet conferencing, telephony, presence, events notification, instant messaging, and the like. SIP signaling uses a long-term stable identifier, the SIP Universal Resource Indicator (URI). User equipment (UE) in an IMS refers to a device that contains the SIP User Agent that will initiate or terminate SIP sessions. In particular, one form of UE is a mobile terminal operative to send and receive data across a defined air interface, such as Wideband Code Division Multiple Access (WCDMA). 
     SIP signaling packets in an IMS network are processed by SIP servers or proxies collectively called Call Session Control Function (CSCF). Different types of CSCFs perform specific functions. 
     A Proxy-CSCF (P-CSCF) is a SIP proxy that is the first point of contact for an IMS terminal (UE). The P-CSCF may reside in the terminal&#39;s H-PLMN or a V-PLMN. In either case, a P-CSCF is assigned to a UE during registration, which does not change for the duration of the registration. All SIP messages to and from the UE pass through the P-CSCF, which can inspect them. The P-CSCF performs authentication and security functions for the UE, and maintains records of communications for billing. 
     A Serving-CSCF (S-CSCF) is the central SIP proxy in a UE&#39;s H-PLMN that performs SIP services and session control. Based on information from a Home Subscriber Server (HSS) database, the S-CSCF handles SIP registrations, in which it binds the UE IP address to a SIP address. The S-CSCF also can intercept and inspect all SIP messages to and from the UE. The S-CSCF decides to which application server (AS) the SIP messages will be forwarded, to obtain their services. The S-CSCF also provides routing services, typically using Electronic Numbering (ENUM) lookups, and it enforces network operator policies. 
     An Interrogating-CSCF (I-CSCF) is a SIP proxy located at the edge of an administrative domain. The IP address of the I-CSCF is published in the Domain Name System (DNS) of the domain, so that remote servers can find it, and use it as a forwarding point for SIP packets into the I-CSCF&#39;s domain. The I-CSCF retrieves the subscriber location from the HSS, and then routes SIP requests to its assigned S-CSCF. 
     An IMS network includes a Home Subscriber Server (HSS) that stores the relevant user data including authentication information and service data. As part of the user profile, initial Filter Criteria (iFC) are defined to indicate which application servers are to be invoked based on information in the signaling plane. 
     An IMS network also includes one or more Application Servers (AS) providing various services, such as audio and video broadcast or streaming, push-to-talk, videoconferencing, games, file sharing, e-mail, and the like. Application Servers are invoked based on the iFCs that are stored in the user profile. The S-CSCF will pass signaling onto an AS if the criteria defined in the iFC are met. Once invoked, the AS can take part in the session and provide additional capabilities. 
       FIG. 1  (PRIOR ART) is a simplified functional block diagram of an exemplary IMS network  10 . A UE  12  (incorporating a SIP agent  13 ) has associated with it one or more CSCFs (e.g., a P-CSCF, S-CSCF, and/or I-CSCF)  14 . The CSCF  14  is connected to one or more various ASs  16  and  18  providing services. A HSS  20  (which stores UE authorization information  21  and user profile/iFCs  22 ) provides information for Authentication, Authorization and Accounting (AAA) functions. 
     The Diameter protocol is an advanced, extensible AAA protocol, derived from the industry standard RADIUS (Remote Authentication Dial-In User Service) protocol. Diameter includes numerous enhancements to RADIUS, such as error handling and message delivery reliability. It extracts the essence of the AAA protocol from RADIUS and defines a set of messages that are general enough to form the core of a Diameter base protocol. The various applications that require AAA functions can define their own extensions on top of the Diameter base protocol, and can benefit from the general capabilities provided by the Diameter base protocol. 
       FIG. 2  (PRIOR ART) depicts a representative prior art call flow for a UE to UE call, in which preconditions are used to avoid a problem known as “ghost ringing.” This is accomplished by ensuring that radio resources are reserved on the calling party&#39;s side (UE #1) before alerting the called party (UE #2). The call flow with preconditions of  FIG. 2  (PRIOR ART) is extracted from section 5.1.2.3 of 3GPP TR 24.930 V.7.5.0, the disclosure of which is incorporated herein by reference in its entirety. Hence, a skilled person would readily understand steps  201 - 244  where only the steps relevant to the discussion herein are described. 
     When the called and calling UEs are mobile satellite terminals, the call flow of  FIG. 2  (PRIOR ART) presents several problems. First, if the called UE #2 is located where there is no satellite coverage, such as inside a building, the SIP INVITE message at step  207  will never reach the called UE #2 unless the satellite initiates a High Penetration Alert (HPA) page. The HPA page is a paging message transmitted at much higher power than a normal page. The HPA page directs the called UE #2 to display a message asking the called party to exit the building (or otherwise move into an area of satellite coverage) to receive the call. One solution is for the satellite Radio Access Network (RAN) (not shown) to send a HPA page on every SIP INVITE, regardless of session establishment type (e.g. voice calls, messaging). However, this approach severely impacts radio resources. 
     Additionally, the codec negotiation of steps  217  to  232  result from Network Requested Secondary PDP Context Activation (NRSPCA) on Answer that is, no PDP context is established until the called UE #2 is reached via initial SIP signaling. While NRSPCA on Answer has some advantages in terrestrial networks, such as ensuring that network resources are available and reserved prior to connecting the call, it entails extensive SIP messaging between the two UEs. When a call is established over a satellite, the voluminous exchange of SIP messages not only consumes satellite link bandwidth, it also increases the call setup time. 
     SUMMARY 
     According to one or more embodiments of the present invention described and claimed herein, call placement to or from satellite UEs is optimized by reducing IMS message exchanges, the originating party has control over QoS parameters, a HPA subscription service is made available, and calls to a terminating satellite UE that is shielded from satellite coverage are completed by selectively employing HPA pages. For a call request without preconditions, an AS (originating AS) associated with an originating UE interacts with the PCRF (originating PCRF) to initiate a NRSPCA on Offer instead of using the standard NRSPCA on Answer. An AS (terminating AS) associated with a terminating satellite UE checks for HPA subscription by the user of the terminating satellite UE. If subscribed, the AS (terminating AS) associated with the terminating satellite UE interacts with the PCRF (terminating PCRF) to (1) initiate an NRSPCA on Offer and (2) initiate transmission of a HPA page to the terminating satellite UE. 
     One embodiment relates to an originating AS and method implemented by the same for establishing a call between an originating UE and a terminating satellite UE. The originating AS comprises at least a processor and a memory that stores processor-executable instructions where the processor interfaces with the memory and executes the processor-executable instructions to enable at least the following steps 1 and 2. At step 1, the originating AS receives from the originating access network (e.g., S-CSCF) a SIP INVITE message which is associated with the call for the terminating satellite UE. At step 2, the originating AS sends to the originating PCRF an AAR message to initiate a NRSPCA on Offer to establish a secondary PDP context between the originating access network and the originating UE via the originating RAN. In one embodiment, the AAR message is sent by the originating AS to the originating PCRF only if a Require header field and a Supported header field in the received SIP INVITE message do not contain preconditions and a SDP portion of the SIP INVITE message does not contain “desired QoS” and “current QoS.” If desired, the AAR message may further include an AVP which indicates to the originating PCRF that the call requires NRSPCA on Offer such that the PCRF delays sending an AAA message back to the AS until the originating PCRF receives an indication of successful secondary PDP context activation from the originating access network (e.g., GGSN). An advantage of this is that the originating AS helps reduce IMS message exchanges. 
     Another embodiment relates to an originating PCRF and method implemented by the same for establishing a call between an originating UE and a terminating satellite UE. The originating PCRF comprises at least a processor and a memory that stores processor-executable instructions where the processor interfaces with the memory and executes the processor-executable instructions to enable at least the following steps 1, 2, 3, 4, 5, 6, 7, and 8. At step 1, the originating PCRF receives from the originating AS an AAR to initiate a NRSPCA on Offer to establish a secondary PDP context between the access network and the originating UE via the originating radio access network. At step 2, the originating PCRF determines if the AAR indicates the NRSPCA on Offer. If the result of the determine step 2 is that the AAR does indicate the NRSPCA on Offer, then the originating PCRF performs the following steps: (a) generate charging rules per media component (step 3); (b) obtain QoS information per media component (step 4); (c) initiate the NRSPCA on Offer by sending a RAR message to the originating access network (e.g., GGSN) (step 5); (d) wait to receive a RAA message from the originating access network (e.g., GGSN) which confirms establishment of the secondary PDP context between the originating access network and the originating UE via the originating radio access network (step 6); (e) upon receipt of the RAA message from the originating access network (e.g., GGSN), send an AAA message back to the originating AS (step 7). If the result of the determine step 2 is that the AAR does not indicate the NRSPCA on Offer, then the originating PCRF sets up a NRSPCA on Answer (step 8). An advantage of this is that the originating PCRF helps reduce IMS message exchanges. 
     Another embodiment relates to a terminating AS and method implemented by the same for establishing a call between an originating UE and a terminating satellite UE. The terminating AS comprises at least a processor and a memory that stores processor-executable instructions where the processor interfaces with the memory and executes the processor-executable instructions to enable at least the following steps 1, 2, 3 and 4. At step 1, the terminating AS receives from the terminating access network (e.g., S-CSCF) a SIP INVITE message associated with the call for the terminating satellite UE. At step 2, the terminating AS retrieves a HPA subscription if any associated with the terminating satellite UE. For instance, the terminating AS upon receiving the SIP INVITE message can retrieve the HPA subscription from the HSS over the Sh interface (step 2a). Or, the terminating AS can retrieve the HPA subscription from the HSS over the Sh interface when the UE B first registers with IMS network (step 2b). Alternatively, the terminating AS can retrieve the HPA subscription which is stored locally in the terminating AS (step 2c). At step 3, the terminating AS upon determining that the terminating satellite UE has the HPA subscription operates to send the terminating PCRF an AAR message to (1) initiate a NRSPCA on Offer to establish a secondary PDP context between the terminating access network and the terminating satellite UE via the terminating satellite radio access network, and (2) initiate transmission of a HPA page to the terminating satellite UE. In one embodiment, the terminating AS sends the AAR message to the terminating PCRF only if the terminating satellite UE has the HPA subscription and a Require header field and a Supported header field in the received SIP INVITE message do not contain preconditions and a SDP portion of the SIP INVITE message does not contain “desired QoS” and “current QoS.” If desired, the AAR can include an AVP indicating to the terminating PCRF that the call requires NRSPCA on Offer such that the PCRF delays sending an AAA message back to the AS until the PCRF receives an indication of a successful secondary PDP context activation from the terminating access network (e.g., GGSN). An advantage of this is that the terminating AS helps reduce IMS message exchanges and helps initiate the HPA page to the terminating satellite UE. 
     Yet another embodiment relates to a terminating PCRF and method implemented by the same for establishing a call between an originating UE and a terminating satellite UE. The terminating PCRF comprises at least a processor and a memory that stores processor-executable instructions where the processor interfaces with the memory and executes the processor-executable instructions to enable at least the following steps 1, 2, 3, 4, 5, 6, 7, and 8. At step 1, the terminating PCRF receives from the terminating AS an AAR to initiate a NRSPCA on Offer to establish a secondary PDP context between the terminating access network and the terminating satellite UE via the terminating radio access network. At step 2, the terminating PCRF determines if the AAR indicates the NRSPCA on Offer. If the result of the determine step 2 is that the AAR does indicate the NRSPCA on Offer, then the terminating PCRF performs the following steps: (a) generate charging rules per media component (step 3); (b) obtain QoS information per media component (step 4); (c) initiate the NRSPCA on Offer by sending a RAR message to the terminating access network (e.g., GGSN) (step 5); (d) wait to receive a RAA message from the terminating access network (e.g., GGSN) which confirms establishment of the secondary PDP context between the terminating access network and the terminating satellite UE via the terminating radio access network (step 6); (e) upon receipt of the RAA message from the terminating access network (e.g., GGSN), send an AAA message back to the terminating AS (step 7). If the result of the determine step 2 is that the AAR does not indicate the NRSPCA on Offer, then the terminating PCRF sets up a NRSPCA on Answer (step 8). An advantage of this is that the terminating PCRF helps reduce IMS message exchanges. 
     In yet another embodiment relates to a terminating satellite RAN and method implemented by the same for establishing a call between an originating UE and a terminating satellite UE. The terminating satellite RAN comprises at least a processor and a memory that stores processor-executable instructions where the processor interfaces with the memory and executes the processor-executable instructions to enable at least the following steps 1, 2, 3, and 4. At step 1, the terminating satellite RAN receives from the terminating access network (e.g., SGSN) a HPA message which is to be transmitted to the terminating satellite UE. At step 2, the terminating satellite RAN determines if the HPA message indicates that the call is a conversational call or interactive call. If the result of the determine step 2 is that the HPA message indicates that the call is a conversational call or interactive call, then the terminating satellite RAN at step 3 sends a HPA page to the terminating satellite UE. If the result of the determine step 2 is that the HPA message indicates that the call is not a conversational call or interactive call, then the terminating satellite RAN at step 4 sends a non-HPA page to the terminating satellite UE. An advantage of this is that the terminating satellite RAN selectively employs HPA pages for conversational/interactive calls. 
     Additional embodiments of the invention will be set forth, in part, in the detailed description, figures and any claims which follow, and in part will be derived from the detailed description, or can be learned by practice of the invention. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as disclosed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete understanding of the present invention may be obtained by reference to the following detailed description when taken in conjunction with the accompanying drawings: 
         FIG. 1  (PRIOR ART) is a functional block diagram of a conventional IMS network; 
         FIG. 2  (PRIOR ART) is a call flow diagram of conventional call setup in an IMS network; 
         FIG. 3A  is a functional block diagram of a satellite RAN integrated with an IMS network which is used to help explain the different embodiments of the present invention; 
         FIG. 3B  depicts a portion of the integrated satellite/IMS network shown in  FIG. 3A  which is referred to herein as the HPA IMS node level architecture and is used along with several different signal flow diagrams to help explain the different embodiments of the present invention; 
         FIGS. 4A-4B  illustrate a signal flow diagram used to explain the signaling for a voice call NRSPCA on Offer call flow on the originating side in accordance with an embodiment of the present invention; 
         FIGS. 5A-5B  illustrate a signal flow diagram used to explain the signaling for a voice call NRSPCA on Offer call flow on the terminating side in accordance with an embodiment of the present invention; 
         FIGS. 6A-1, 6A-2, 6A-3, 6A-4, 6B-1, 6B-2, 6B-3, 6B-4, 6C-1, 6C-2, 6C - 3 ,  6 C- 4 ,  6 D- 1 ,  6 D- 2 ,  6 D- 3 ,  6 D- 4 ,  6 E- 1 ,  6 E- 2 ,  6 E- 3 ,  6 E- 4 ,  6 F- 1 ,  6 F- 2 ,  6 G- 1 ,  6 G- 2 ,  6 H- 1 ,  6 H- 2 ,  6 H- 3 ,  6 H- 4 ,  6 I- 1 , and  6 I- 2  illustrate a detailed end-to-end call signal flow diagram that illustrates the NRSPCA on Offer procedure together with HPA paging for conversational services when the terminating satellite UE is inside a building in accordance with different embodiments of the present invention; 
         FIG. 7  is a flowchart illustrating a method which is implemented by an originating AS when establishing a call between an originating UE and a terminating satellite UE in accordance with an embodiment of the present invention; 
         FIG. 8  is a flowchart illustrating a method which is implemented by an originating PCRF when establishing a call between an originating UE and a terminating satellite UE in accordance with an embodiment of the present invention; 
         FIG. 9  is a flowchart illustrating a method which is implemented by a terminating AS when establishing a call between an originating UE and a terminating satellite UE in accordance with an embodiment of the present invention; 
         FIG. 10  is a flowchart illustrating a method which is implemented by a terminating PCRF when establishing a call between an originating UE and a terminating satellite UE in accordance with an embodiment of the present invention; and 
         FIG. 11  is a flowchart illustrating a method which is implemented by a terminating satellite RAN when establishing a call between an originating UE and a terminating satellite UE in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 3A  depicts an integrated satellite/IMS network  22  which has an AS  16 , an PCRF  42  and a HSS  50  which have been enhanced in accordance with different embodiments of the present invention. In this example, the integrated satellite/IMS network  22  connects satellite mobile terminals  24   a  and  24   b  (which have built-in IMS clients-SIP agents  13 ) with each other by using the application server  26  and other resources in an IMS network  41 . Alternatively, the integrated satellite/IMS network  22  can also connect satellite mobile terminal  24   b  (for example) with communication terminals (not satellite mobile terminal  24   a ) located in other networks, such as the Public Switched Telephone Network (PSTN)  30 . In the present example, traffic to and from the satellite mobile terminals  24   a  and  24   b  is transmitted by one or more satellites  32 , with access controlled by a satellite Radio Access Network (RAN)  34 . The satellite RAN  34  is communicatively coupled to a terrestrial wireless IP Connectivity Access Network (IP-CAN)  36 . In the example depicted in  FIG. 3A , the wireless IP-CAN  36  is a Wideband Code Division Multiple Access (WCDMA) network with General Packet Radio Service (GPRS) comprising at least a Gateway GPRS Service Node (GGSN)  38  and a Serving GPRS Support Node (SGSN)  40 . The WCDMA IP-CAN  36  is connected to the IMS network  41  comprising a Policy and Charging Rule Function (PCRF)  42 , a P-CSCF  44 , a S-CSCF  46 , and an application server  26  (which includes HPA/NRSPCA logic  27 ). 
     The IMS network  41  additionally comprises a Home Location Register (HLR)  48  and a HSS  50  (which stores information about HPA subscriptions  51 ), a Media Resource Function  52  comprising a Media Resource Function Controller (MRFC) and a Media Resource Function Processor (MRFP), and a server  54  performing address lookup and translation functions such as DNS, Electronic Numbering (ENUM), and Dynamic Host Configuration Protocol (DHCP). The IMS network  41  further includes a Media Gateway Controller Function (MGCF) and Signaling Gateway (SGW)  56  connected to a Media Gateway (MGW)  58  across a H.248 interface. The structure and operation of the IMS network  41  is well defined and understood by those skilled in the art, and is not further explained herein. Those of skill in the art will further recognize the existence of a packet core, comprising switches and routers (not shown), that carries bearer traffic between the GGSN  38  and MGW  58 . 
       FIG. 3A  also depicts a voice or interactive call directed to satellite mobile UE  24   b  which is now located in a building  60 . A High Penetration Alert (HPA) page  61  is selectively employed to reach the called UE  24 . The HPA displays a message, such as that depicted, that the user has an incoming call, and requesting the user to exit the building  60  to receive the call from the satellite  32 . According to embodiments described herein, the HPA page  61  is selectively employed based on the type of call, the state of the called UE  24   b , and whether the called user subscribes to a HPA service. 
     The operation of various embodiments of the present invention are described herein in the context of a voice call from one satellite UE  24   a  (identified as user “A” or “UE A”) to another satellite UE  24   b  (identified as user “B” or “UE B)), when UE B is in the building  60 . Both the originating mobile satellite UE  24   a  and the terminating mobile satellite UE  24   b  typically include a special codec to optimize the transmission of voice packet over the satellite link. In this case, the standard IMS call flow can be enhanced to (for example): (1) give the originating mobile satellite UE  24  full control in providing Quality of Service (QoS) for various end user services; (2) increase successful call establishment rate without wasting satellite radio resources by using HPA paging only for selected bearer services (e.g., only voice and interactive calls); and (3) charge mobile satellite subscribers for subscribing to HPA as a service. 
       FIG. 3B  depicts a portion of the integrated satellite/IMS network  22  which is referred to herein as the HPA IMS node level architecture and is used along with several different signal flow diagrams to help explain the different embodiments of the present invention. The HPA IMS node level architecture includes the AS  26  (which includes HPA/NRSPCA Logic  27 ) that is operatively connected via the Sh interface to the HSS  50  (which stores HPA subscriptions  51 ). In addition, the AS  26  is operatively connected via the ISC interface to S-CSCF  46  (which is connected to P-CSCF  44 ). Furthermore, the AS  26  is operatively connected via Rx interface to the PCRF  42 . In the present invention and as will be discussed in detail below, an originating call (e.g., from UE A  24   a ) and a terminating call (e.g., to UE B  24   b ) are triggered to be processed by an AS  26  (note: as discussed below one AS  26  may be used to process an originating call from the originating UE  24   a  and another AS  26  may be used to process a terminating call to the terminating UE  24   b ). The AS  26  processes the originating call using the HPA/NRSPCA logic  27  and sets up the Network Initiated Secondary PDP Context (NRSPCA) on Offer through the PCRF  42  to establish a secondary PDP context between the WCDMA access network  36  and the originating UE A  24   a . Furthermore, the AS  26  processes the terminating call using the HPA/NRSPCA logic  27  and sets up the Network Initiated Secondary PDP Context (NRSPCA) on Offer through the PCRF  42  to establish a secondary PDP context between the WCDMA access network  36  and the terminating UE B  24   b . The AS  26  also fetches the subscriber information for the terminating UE B  24   b  to determine if they have a HPA subscription  51 . If the terminating UE B  24   b  has a HPA subscription  51 , then the AS  26  triggers a HPA page  61  towards the WCDMA access network  36  and Satellite RAN  34 . The AS  26  also charges UE B  24   b  for subscribing and using HPA as a service. 
     The service logic in the IMS nodes AS  26 , PCRF  42 , and the satellite RAN  34  required to support the features described above namely the NRSPCA on Offer and the HPA are described in detail below, for both the originating and terminating sides. For the purpose of explanation, both the originating mobile UE  24   a  (UE A) and terminating mobile UE  24   b  (UE B) are considered as mobile satellite subscribers as the most general case. However, in general, either of them could be a PSTN or PLMN subscriber and the logic for the other subscriber would remain unchanged. 
     Example #1 
     Service Logic 
     Originating Side Service Logic 
       FIGS. 4A-4B  illustrate a signal flow diagram used to explain the signaling for a voice call NRSPCA on Offer call flow on the originating side in accordance with an embodiment of the present invention. In this signal flow diagram, the components shown are as follows: the originating satellite mobile UE  24   a  (UE A), the satellite RAN  34   a , the originating SGSN  40   a , the originating GGSN  38   a , the originating PCRF  42   a , the originating P-CSCF  44   a , the originating S-CSCF  46   a , and the originating AS  26   a . A step-by-step discussion is provided as follows: 
     1. The originating S-CSCF  46   a  receives a call (SIP INVITE message—with SDP A—associated with UE A  26   a ) from the originating satellite mobile UE  24   a  via the satellite RAN  34   a , the originating GGSN  38   a , and the originating P-CSCF  44   a . The originating S-CSCF  46   a  routes the SIP INVITE message to the originating AS  26   a.    
     2. The originating AS  26   a  sends a Diameter AAR message containing UE A&#39;s SDP to the originating PCRF  42   a  to trigger the NRSPCA on Offer procedure. The AAR message has key AVPs which are set as follows:
         The Specific-Action AVP is set to INDICATION_OF_SUCCESSFUL_RESOURCES_ALLOCATION to indicate subscription to the Resource Reservation Completion event.   The SERVICE_INFO_STATUS AVP is set to PRELIMINARY_SERVICE_INFORMATION.       

     3. The originating PCRF  42   a  sends AAA back to the originating AS  26   a.    
     4. The originating PCRF  42   a  sends a RAR message to the originating GGSN  38   a . The originating PCRF  42   a  indicates the subscription to the Resource Reservation Completion event to the originating GGSN  38   a  as follows:
         The Event-Trigger AVP is set to SUCCESSFUL_RESOURCE_ALLOCATION.   The Resource-Allocation-Notification AVP of the Charging-Rule-Install AVP is set to Enable-Notification.       

     5. The originating GGSN  38   a  sends RAA back to originating PCRF  42   a  to acknowledge the receipt of the RAR. 
     6. The originating GGSN  38   a  sends Initiate PDP Context Activation Request message to the originating SGSN  40   a.    
     7. The originating SGSN  40   a  maps the ARP received in the Initiate PDP Context Activation Request message to the Precedence Class and sends Request Secondary PDP Context Activation to UE A  24   a  to establish a dedicated secondary PDP Context for voice call. 
     8. UE A  24   a  sends Activate Secondary PDP Context Request to the originating SGSN  40   a.    
     9. The originating SGSN  40   a  sends Initiate PDP Context Activation Response to the originating GGSN  38   a.    
     10. The originating GGSN  38   a  sends Create PDP Context Activation Request to the originating SGSN  40   a.    
     11. The originating SGSN  40   a  sends Create PDP Context Activation Response to the originating GGSN  38   a.    
     12. The originating SGSN  40   a  sends RAB Assignment Request to the RAN  34   a.    
     13. The RAN  34   a  sends RAB Assignment Response to the originating SGSN  40   a.    
     14. The originating SGSN  40   a  sends Update PDP Context Request to the originating GGSN  38   a.    
     15. The originating GGSN  38   a  sends Update PDP Context Response to the originating SGSN  40   a.    
     16. The originating SGSN  40   a  sends Activate Secondary PDP Context Accept to UE A  24   a.    
     17. The originating GGSN  38   a  sends a CCR (Update) to notify the originating PCRF  42   a  of the Resource Reservation Completion event. The Charging-Rule-Report AVP includes the PCC-Rule-Status AVP set to ACTIVE. The Charging-Rule-Name AVP refers to the applicable PCC rules for which the secondary PDP was activated. 
     18. The originating PCRF  42   a  sends CCA to the originating GGSN  38   a  to acknowledge the CCR. 
     19. The originating PCRF  42   a  sends RAR to notify the originating AS  26   a  of the Resource Reservation Completion event. The Specific-Action AVP is set to INDICATION_OF_SUCCESSFUL_RESOURCES_ALLOCATION together with Flow AVPs referring to the applicable media flows for which the secondary PDP was activated. 
     20. The originating AS  26   a  sends RAA back to the originating PCRF  42   a  to acknowledge the RAR. 
     21. The originating AS  26   a  sends SIP INVITE (with SDP A—associated with UE A  26   a ) to originating S-CSCF  46   a  (which will be sent to UE B  24   b ). Thereafter, UE B  24   b  (not shown) sends 183 Session Progress (SDP B) to the originating S-CSCF  46   a  which sends it to originating AS  26   a . Then, the originating AS  26   a  sends AAR to the originating PCRF  42   a  to update media authorization session. The originating PCRF  42   a  then sends AAA to the originating AS  26   a  to acknowledge the AAR. The AS  26   a  then sends SIP INVITE (SDP B—associated with UE B  26   b ) to originating S-CSCF  46   a.    
     22. The originating S-CSCF  46   a  sends SIP INVITE (with SDP B—associated with UE B  26   b ) to originating P-CSCF  44   a.    
     23. The originating P-CSCF  44   a  sends AAR to originating PCRF  42   a.    
     24. The originating PCRF  42   a  sends AAA to originating P-CSCF  44   a  (Note: steps 22-24 may not necessarily be the preferred signaling process for an alternative signaling process reference is made to  FIG. 6G-1 &#39;s steps 80-82 (discussed below). 
     25. The originating PCRF  42   a  sends RAR to originating GGSN  38   a.    
     26. The originating GGSN  38   a  sends RAA to originating PCRF  42   a.    
     27-30. The originating GGSN  38   a  interacts with the originating SGSN  40   a  and the UE A  24   a  to modify the secondary PDP context. 
     31. 183 Session Progress, 180 Ringing, 200OK (Invite) messaging. 
     Terminating Side Service Logic 
       FIGS. 5A-5B  illustrate a signal flow diagram used to explain the signaling for a voice call NRSPCA on Offer call flow on the terminating side in accordance with an embodiment of the present invention. In this signal flow diagram, the components shown are as follows: the terminating satellite mobile UE  24   b  (UE B), the satellite RAN  34   b , the terminating SGSN  40   b , the terminating GGSN  38   b , the terminating PCRF  42   b , the terminating P-CSCF  44   b , the terminating S-CSCF  46   b , and the terminating AS  26   b . It should be appreciated that the originating components  26   a ,  34   a ,  38   a ,  40   a ,  42   a ,  44   a ,  46   a  etc. . . . are the same as the terminating components  26   b ,  34   b ,  38   b ,  40   b ,  42   b ,  44   b ,  46   b  etc. . . . when both UE A  24   a  and UE B  24   b  are registered with the same integrated satellite/IMS network  22 . If UE A  24   a  and UE B  24   b  are registered with different networks then the originating components  26   a ,  34   a ,  38   a ,  40   a ,  42   a ,  44   a ,  46   a  etc. . . . associated with the UE A&#39;s network would not be the same as the terminating components  26   b ,  34   b ,  38   b ,  40   b ,  42   b ,  44   b ,  46   b  etc. associated with the UE B&#39;s network. A step-by-step discussion is provided as follows: 
     1. The terminating S-CSCF  46   b  receives a call from the originating network. The terminating S-CSCF  46   b  routes the SIP INVITE message (SDP-A associated with UE A  26   a ) to the terminating AS  26   b.    
     2. The terminating AS  26   b  sends a Diameter AAR message containing UE A&#39;s SDP to the terminating PCRF  42   b  to trigger the NRSPCA procedure. The Specific-Action AVP is set to INDICATION_OF_SUCCESSFUL_RESOURCES_ALLOCATION to indicate subscription to the Resource Reservation Completion event. In this example, it is assumed that the terminating AS  26   b  has confirmed that UE B  26   b  has an HPA subscription  51  before sending the AAR message to the terminating PCRF  42   b  (see  FIG. 9 ). 
     3. The terminating PCRF  42   b  sends RAA back to the terminating AS  26   b.    
     4. The terminating PCRF  42   b  sends the RAR message to the terminating GGSN  38   b . The terminating PCRF  42   b  indicates the subscription to the Resource Reservation Completion event for the terminating GGSN  38   b  as follows:
         The Event-Trigger AVP is set to SUCCESSFUL_RESOURCE_ALLOCATION.   The Resource-Allocation-Notification AVP of the Charging-Rule-Install AVP is set to Enable-Notification.       

     5. The terminating GGSN  38   b  sends RAA to acknowledge the receipt of the RAR to the terminating PCRF  42   b.    
     6. The terminating GGSN  38   b  sends Initiate PDP Context Activation Request message to the terminating SGSN  40   b.    
     7. The terminating SGSN  40   b  sends Request Secondary PDP Context Activation (Precedence Class) message to the terminating satellite RAN  34   b.    
     8. The satellite RAN  34   b  sends an HPA message  61  to UE B  26   b . UE B  26   b  displays a message alerting user B of UE B  24   b  of an incoming call. The user B steps outside to receive the call. 
     9. UE B  26   b  sends a Page Response to the satellite RAN  34   b.    
     10. The satellite RAN  34   b  sends Request Secondary PDP Context Activation message to UE B  26   b.    
     11. UE B  26   b  sends Activate Secondary PDP Context Request to the terminating SGSN  40   b.    
     12. The terminating SGSN  40   b  sends Initiate PDP Context Activation Response to the terminating GGSN  38   b.    
     13. The terminating SGSN  40   b  sends Create PDP Context Request to the terminating GGSN  38   b.    
     14. The terminating GGSN  38   b  sends Create PDP Context Response to the terminating SGSN  40   b.    
     15. The terminating SGSN  40   b  sends RAB Assignment Request to the satellite RAN  34   b.    
     16. The satellite RAN  34   b  allocates radio traffic channels with media diversity. 
     17. The satellite RAN  34   b  sends RAB Assignment Response to the terminating SGSN  40   b.    
     18. The terminating SGSN  40   b  sends Update PDP Context Request to the terminating GGSN  38   b.    
     19. The terminating GGSN  38   b  sends Update PDP Context Response to the terminating SGSN  40   b.    
     20. The terminating SGSN  40   b  sends Activate Secondary PDP Context Accept to UE B  26   b.    
     21. The terminating GGSN  38   b  sends a CCR (Update) to notify the terminating PCRF  42   b  of the Resource Reservation Completion event. The Charging-Rule-Report AVP includes the PCC-Rule-Status AVP set to ACTIVE. The Charging-Rule-Name AVP refers to the applicable PCC rules for which the secondary PDP was activated. 
     22. The terminating PCRF  42   b  sends RAR to notify the terminating AS  26   b  of the Resource Reservation Completion event. The Specific-Action AVP is set to INDICATION_OF_SUCCESSFUL_RESOURCES_ALLOCATION together with Flow AVPs referring to the applicable media flows for which the secondary PDP was activated. 
     23. The terminating AS  26   b  sends RAA back to the terminating PCRF  42   b  to acknowledge the RAR. 
     24. The terminating AS  26   b  sends SIP INVITE (SDP A—associated with UE A  24   a ) to terminating S-CSCF  46   b.    
     25. The terminating S-CSCF  46   b  sends SIP INVITE (SDP A—associated with UE A  24   a ) to terminating P-CSCF  44   b.    
     26. The terminating P-CSCF  44   b  sends SIP INVITE (SDP A—associated with UE A  24   a ) to UE B  26   b.    
     27. The UE B  26   b  sends 183 (SDP B—associated with UE B  24   b ) message to terminating P-CSCF  44   b.    
     28. Normal signaling continues beyond this point to establish call between UE A  26   a  and UE B  26   b.    
     From the foregoing, it should be appreciated based on  FIGS. 4-5 &#39;s signal flow diagrams that the present invention has many advantages some of which are as follows:
         The present invention optimizes the messaging flow to set up a SIP session (e.g. voice call, video call, Messaging) from or to a mobile satellite terminal using IP Multimedia Subsystem over WCDMA access networks.   The present invention gives the operator full control in providing QoS for various end user services.   The present invention uses High Penetration Alert (HPA) paging only for selected bearer services (e.g. voice calls only).   The present invention charges mobile satellite subscribers for subscribing to HPA as a service.   The present invention optimizes satellite radio resources usage and increases the successful call establishment rate by using Network Request Secondary PDP Context Activation on Offer and HPA to set up mobile satellite UE to mobile satellite UE or PSTN/PLMN device to mobile satellite call.   The present invention reduces the number of SIP messages required to set up a mobile satellite terminal to mobile satellite terminal call over IMS.       

     It should also be appreciated that the present invention has distinct differences when compared to the co-assigned U.S. Publication No. 2011/0075655 A1. Some of these differences are as follows:
         The present invention uses the AS  26 , HSS  50  and/or PCRF  42  to implement the present invention. In contrast, the co-assigned U.S. Publication No. 2011/0075655 A1 uses the P-CSCF and PCRF to implement their invention.   In the present invention, the HPA subscription  51  is stored in the HSS  50 . In the co-assigned U.S. Publication No. 2011/0075655 A1 the HPA subscription was stored in the PCRF. The HSS  50  is a more a more logical node (IMS standard) to store the HPA subscription  51 .   In the present invention, the AS  26  uses a standard interface Sh to retrieve the HPA subscription  51  from the HSS  50 .   In the present invention, the AS  26  generates the charging record (CDR) for the HPA subscription  51  and usage and sends the CDR to the billing system (e.g., the CDR is shown being generated before step  112  in  FIG. 6H-4 ). This is not possible in the co-assigned U.S. Publication No. 2011/0075655 A1 since the P-CSCF cannot generate a charging record.       

     Example #2 
     Service Logic 
       FIGS. 6A-1, 6A-2, 6A-3, 6A-4, 6B-1, 6B-2, 6B-3, 6B-4, 6C-1, 6C-2, 6C - 3 ,  6 C- 4 ,  6 D- 1 ,  6 D- 2 ,  6 D- 3 ,  6 D- 4 ,  6 E- 1 ,  6 E- 2 ,  6 E- 3 ,  6 E- 4 ,  6 F- 1 ,  6 F- 2 ,  6 G- 1 ,  6 G- 2 ,  6 H- 1 ,  6 H- 2 ,  6 H- 3 ,  6 H- 4 ,  6 I- 1 , and  6 I- 2  illustrate a detailed end-to-end call signal flow diagram that illustrates the NRSPCA on Offer procedure together with HPA paging for conversational services when the terminating satellite UE  24   b  is inside a building  61  in accordance with an embodiment of the present invention. In this signal flow diagram, the following components are shown the originating satellite mobile UE A  24   a , the originating RAN  34   a , the originating SGSN  40   a , the originating GGSN  38   a , the originating PCRF  42   a , the originating P-CSCF  44   a , the originating S-CSCF  46   a , the originating AS  26   a , the HSS  50 , the I-CSCF  60 , the terminating satellite mobile UE B  24   b  (UE B), the terminating satellite RAN  34   b , the terminating SGSN  40   b , the terminating GGSN  38   b , the terminating PCRF  42   b , the terminating P-CSCF  44   b , the terminating S-CSCF  46   b , and the terminating AS  26   b . It should be appreciated that the originating components  26   a ,  38   a ,  40   a ,  42   a ,  44   a ,  46   a  etc. . . . are the same as the terminating components  26   b ,  38   b ,  40   b ,  42   b ,  44   b ,  46   b  etc. . . . when both UE A  24   a  and UE B  24   b  are registered with the same integrated satellite/IMS network  22 . If UE A  24   a  and UE B  24   b  are registered with different networks then the originating components  26   a ,  38   a ,  40   a ,  42   a ,  44   a ,  46   a  etc. . . . associated with the UE A&#39;s network would not be the same as the terminating components  26   b ,  38   b ,  40   b ,  42   b ,  44   b ,  46   b  etc. associated with the UE B&#39;s network. 
     Originating Side Service Logic 
     Mobile satellite subscriber A utilizes the originating satellite mobile UE A  24   a  to make a voice call to mobile satellite subscriber B which is utilizing the terminating satellite mobile UE B  24   b . Upon receiving the originating SIP INVITE message at step 5, the subscriber A&#39;s originating AS  26   a  executes the following logic: If the Require header and the Supported header in the SIP INVITE message do not contain preconditions and the SDP portion of the SIP INVITE message does not contain “desired QoS” and “current QoS” then the following steps occur: 
     1. A&#39;s AS  26   a  requests that A&#39;s PCRF  42   a  perform preliminary QoS authorization for an incoming voice call by sending an AAR Diameter request (SERVICE_INFO_STATUS: PRELIMINARY_SERVICE_INFORMATION, Media-Component-Description: Code-Data: “uplink” “offer” . . . ) to PCRF  42   a  (step 7). Alternatively, the AAR can include a new AVP such as NRSPCA_ON_OFFER to indicate to PCRF  42   a  that this is a call that requires NRSPCA on Offer. In which case, the PCRF  42   a  will delay sending AAA back to AS  26   a  until the PCRF  42   a  receives an indication of successful secondary PDP context activation from the GGSN  38   a.    
     2. A&#39;s PCRF  42   a  requests that A&#39;s GGSN  38   a  perform NRSPCA for a voice call by sending a Diameter RAR message to GGSN  38   a  (step 9). 
     3. A&#39;s GGSN  38   a  requests that A&#39;s SGSN  40   a  create a secondary PDP context for a voice call (step 11). 
     4. A&#39;s SGSN  40   a  sends Request PDP Context Activation message to UE A  24   a  (step 12). 
     5. A&#39;s GGSN  38   a , A&#39;s SGSN  40   a , and UE A  24   a  together complete the NRSPCA procedure (steps 13-22). 
     6. A&#39;s AS  26   a  sends the SIP INVITE message back to S-CSCF  46   a  to continue the call (step 27). 
     7. A&#39;s S-CSCF  46   a  sends SIP INVITE message to B&#39;s I-CSCF  60  (if any) which interacts with HSS  50  and B&#39;s S-CSCF  46   b  to route the call to B&#39;s S-CSCF  46   b  (step 33). 
     Otherwise, if A&#39;s AS  26   a  determines that the Require header and the Supported header in the INVITE do contain preconditions and the SDP portion of the SIP INVITE message contain “desired QoS” and “current QoS” then A&#39;s AS  26   a  implements the existing originating AS service logic (see box between steps 6 and 7) where the AS  26   a  sends the SIP INVITE message to the originating S-CSCF to continue the call. 
     Terminating Side Service Logic 
     When B&#39;s AS  26   b  receives the terminating SIP INVITE message (step 35), then B&#39;s AS  26   b  executes the following service logic: If the Require header and the Supported header in the INVITE do not contain preconditions and the SDP portion of the INVITE does not contain “desired QoS” and “current QoS” then B&#39;s AS  26   b  retrieves B&#39;s HPA subscription  51  using anyone of several techniques. For example, B&#39;s AS  26   b  retrieves B&#39;s HPA subscription  51  from the HSS  50  upon receiving the SIP INVITE message (between steps 35 and 36). Or, B&#39;s AS  26   b  retrieves B&#39;s HPA subscription  51  from the HSS  50  when the UE B  24   b  first registers with IMS network  41  (see note between steps 35 and 36). Or, B&#39;s AS  26   b  retrieves B&#39;s HPA subscription  51  which is stored locally within the terminating AS  26   b  (see note between steps 35 and 36). After, B&#39;s AS  26   b  retrieves the B&#39;s HPA subscription  51  then the following steps are performed: 
     1. If B&#39;s AS  26   b  determines B&#39;s HPA subscription  51  is active, then B&#39;s AS  26   b  requests that B&#39;s PCRF  42   b  perform preliminary QoS authorization for an incoming voice call by sending an AAR including a new AVP named NRSPCA_ON_OFFER AVP to B&#39;s PCRF  42   b  (step 37). If B does not subscribe to HPA, then B&#39;s AS  26   b  performs existing logic by sending the SIP INVITE message to the terminating S-CSCF  46   b  for processing (these steps are not shown because in the current discussion it is assumed that B subscribes to HPA). 
     2. B&#39;s PCRF  42   b  requests that B&#39;s GGSN  38   b  perform NRSPCA for an incoming voice call by sending a Diameter RAR message to B&#39;s GGSN  38   b  (step 39). 
     3. B&#39;s GGSN  38   b  requests that B&#39;s SGSN  40   b  create a secondary PDP context for a terminating voice call by sending a PDU Context Activation Request message to B&#39;s SGSN  40   b  (step 41). 
     4. If B is inside a building  61 , UE B&#39;s  24   b  PMM state should be PMM IDLE. Therefore, B&#39;s SGSN  40   b  sends a Page message (Cause IE: “Terminating Conversational Call”) to the satellite RAN  34   b  (step 42). 
     5. Since the Paging Cause IE is set to “Terminating Conversational Call”, the satellite RAN  34   b  sends an HPA page to UE B  24   b  (step 43). 
     6. B receives a message on his/her UE B  24   b  saying something like this “There is an incoming voice call for you. If you are inside a building, please step outside the building to answer it” (between steps 43 and 44). 
     7. B steps outside the building  61  with UE B  24   b  to get ready to receive the SIP INVITE message (between steps 43 and 44). 
     8. B&#39;s GGSN  38   b , B&#39;s SGSN  40   b , B&#39;s satellite RAN  34   b , and B&#39;s UE  24   b  together complete the NRSPCA procedure (steps 44-56). 
     9. B&#39;s PCRF  42   b  informs B&#39;s AS  26   b  that NRSPCA on Offer is completed by sending RAR message to B&#39;s AS  26   b  (step 59). 
     10. B&#39;s AS  26   b  returns the SIP INVITE to B&#39;s S-CSCF  46   b  which sends it to UE B  24   b  via B&#39;s P-CSCF  44   b  (steps 61-65). 
     11. UE B  24   b , B&#39;s AS  26   b  etc. . . . exchange  100  Trying messaging, followed by 180 Ringing messaging, and 200OK (INVITE) with SDP messaging (step 66-101). 
     12. B&#39;s PCRF  42   b  performs final QoS authorization (steps 104-107). 
     13. Normal signaling continues beyond this point to establish call between UE A  26   a  and UE B  26   b  (steps 108-142). 
     From the foregoing, it should be appreciated in view of  FIG. 6 &#39;s signal flow diagram that the present invention has many advantages some of which are as follows:
         The present invention by using the Network Requested Secondary PDP Context Activation (NRSPCA) on Offer instead of using the standard UE initiated Secondary PDP Context Activation procedure is able to eliminate preconditions and reduces by half the number of messaging exchange (no PRACK, UPDATE, and corresponding 200OKs) between the originating mobile satellite terminal UE A  24   a  and the terminating mobile satellite terminal UE B  24   b . In addition, NRSPCA on Offer gives the operator full control in providing QoS for various end user services as the network instructs the UE A  24   a  and UE B  24   b  what QoS parameter values to use thus avoiding pre-provisioning of terminals.   The present invention by having the terminating AS  26   b  check for the HPA subscription  51  before initiating NRSPCA which triggers HPA allows the mobile satellite operator to charge subscribers for using HPA.   The present invention by having the satellite RAN  34   b  configured to send the HPA to the terminating satellite UE B  24   b  only when the terminating SIP INVITE request is for a “Terminating Conversational Call/Interactive Call” (e.g. a voice call or a push-to-talk request) optimizes page channel resource usage.   The present invention enables the terminating AS  26   b  to generate charging records for the HPA subscription and usage.   The present invention optimizes satellite radio resources usage and increases the successful call establishment rate by using Network Request Secondary PDP Context Activation on Offer and HPA to set up the mobile satellite to mobile satellite call or PSTN/PLMN device to mobile satellite call.   The present invention effectively reduces the number of SIP messages required to set up a mobile satellite to mobile satellite calls over IMS. The following TABLE #1 shows the processing time for a standard Mobile to PSTN call without NRSPCA on INVITE.       

     
       
         
               
               
               
             
               
               
               
             
           
               
                 TABLE #1 
               
               
                   
               
             
             
               
                   
                 Message or Event 
                 Delay (ms) 
               
               
                   
               
               
                   
                 Uplink Assignment 
                   32 
               
               
                   
                 |-------- INVITE -------&gt;| 
                  533 
               
               
                   
                 |&lt;-- 183 Session Progress ---| 
                  433 
               
               
                   
                 |------- PRACK -------&gt;| 
                  225 
               
               
                   
                 |&lt;---- 200 OK (PRACK) -----| 
                  266 
               
               
                   
                 |&lt;...... Secondary PDP Context .......&gt;| 
                 1500 
               
               
                   
                 |-------- UPDATE --------&gt;| 
                  533 
               
               
                   
                 |&lt;--- 200 OK (UPDATE) ----| 
                  391 
               
               
                   
                 |&lt;---- 180 Ringing -----| 
                  208 
               
               
                   
                 |------- PRACK -----  &gt;| 
                  225 
               
               
                   
                 |&lt;---- 200 OK (PRACK) ------| 
                  266 
               
               
                   
                 |&lt;------- 200 OK -------| 
                  391 
               
               
                   
                 Total Delay 
                 5000 
               
               
                   
               
             
          
           
               
                 RTT (ms) 
                 31.5 
                   
               
               
                 Link Speed (kbps) 
                 9.6 
                   
               
               
                 PDP Context (ms) 
                 1500 
                   
               
             
          
         
       
         
         
           
             The NRSPCA can reduce call setup time by a minimum of 2 seconds. For a mobile to mobile call, per the present invention the time saving will be even more due to the elimination of PRACK/200OK, UPDATE/200OK over the radio link to the terminating satellite UE B  24   b.    
             The present invention gives the operator full control in providing QoS for various end user services thus avoiding QoS configuration in a variety of terminals from different vendors. 
           
         
       
    
     Referring to  FIG. 7 , there is a flowchart illustrating a method  700  which is implemented by an originating AS  26   a  when establishing a call between an originating UE  24   a  and a terminating satellite UE  24   b  in accordance with an embodiment of the present invention. The originating AS  26   a  comprises at least a processor  701  and a memory  703  that stores processor-executable instructions where the processor  701  interfaces with the memory  703  and executes the processor-executable instructions to enable steps  702  and  704 . At step  702 , the originating AS  26   a  receives from the originating S-CSCF  46   a  a SIP INVITE message which is associated with the call for the terminating satellite UE  24   b  ( FIG. 4 &#39;s step 1 and  FIG. 6 &#39;s step 5). At step  704 , the originating AS  26   a  sends to the originating PCRF  42   a  an AAR message to initiate a NRSPCA on Offer to establish a secondary PDP context between the originating access network  36   a  and the originating UE  24   a  via the originating RAN  34   a . In one embodiment, the AAR message is sent to the originating PCRF  42   a  only if a Require header field and a Supported header field in the received SIP INVITE message do not contain preconditions and a SDP portion of the SIP INVITE message does not contain “desired QoS” and “current QoS.” If desired, the AAR message may further include an AVP which indicates to the originating PCRF  42   a  that the call requires NRSPCA on Offer such that the PCRF  42   a  delays sending an AAA message back to the AS  26   a  until the PCRF  42   a  receives an indication of successful secondary PDP context activation from the originating GGSN  38   a . The originating AS  26   a  can also perform other steps which have been described above with respect to  FIG. 4  and  FIG. 6 . 
     Referring to  FIG. 8 , there is a flowchart illustrating a method  800  which is implemented by an originating PCRF  42   a  when establishing a call between an originating UE  24   a  and a terminating satellite UE  24   b  in accordance with an embodiment of the present invention. The originating PCRF  42   a  comprises at least a processor  801  and a memory  803  that stores processor-executable instructions where the processor  801  interfaces with the memory  803  and executes the processor-executable instructions to enable steps  802 ,  804 ,  806 ,  808 ,  810 ,  812 ,  814 , and  816 . At step  802 , the originating PCRF  42   a  receives from the originating AS  26   a  an AAR to initiate a NRSPCA on Offer to establish a secondary PDP context between the originating access network  36   a  and the originating UE  24   a  via the originating radio access network  34   a . At step  804 , the originating PCRF  42   a  determines if the AAR indicates the NRSPCA on Offer. If the result of the determine step  804  is that the AAR does indicate the NRSPCA on Offer, then the originating PCRF  42   a  performs the following steps: (a) generate charging rules per media component (step  806 ); (b) obtain QoS information per media component (step  808 ); (c) initiate the NRSPCA on Offer by sending a RAR message to the originating access network  36   a  (e.g., GGSN  38   a ) (step  810 ); (d) wait to receive a RAA message from the originating access network  36   a  (e.g., GGSN  38   a ) which confirms establishment of the secondary PDP context between the access network  36   a  and the originating UE  24   a  via the radio access network  34   a  (step  812 ); (e) upon receipt of the RAA message from the originating access network  36   a  (e.g., GGSN  38   a ), send an AAA message back to the originating AS  26   a  (step  814 ). If the result of the determine step  804  is that the AAR does not indicate the NRSPCA on Offer, then the originating PCRF  42   a  at step  816  sets up a NRSPCA on Answer. The originating PCRF  42   a  can also perform other steps which have been described above with respect to  FIG. 4  and  FIG. 6 . 
     Referring to  FIG. 9 , there is a flowchart illustrating a method  900  which is implemented by a terminating AS  26   b  when establishing a call between an originating UE  24   a  and a terminating satellite UE  24   b  in accordance with an embodiment of the present invention. The terminating AS  26   b  comprises at least a processor  901  and a memory  903  that stores processor-executable instructions where the processor  901  interfaces with the memory  903  and executes the processor-executable instructions to enable steps  902 ,  904 ,  906 , and  908 . At step  902 , the terminating AS  26   b  receives from the terminating access network  36   b  (e.g., S-CSCF  46   b ) a SIP INVITE message associated with the call for the terminating satellite UE  24   b . At step  904 , the terminating AS  26   b  retrieves a HPA subscription  51  if any associated with the terminating satellite UE  24   b . For instance, the terminating AS  26   b  upon receiving the SIP INVITE message can retrieve the HPA subscription  51  from the HSS  50  over the Sh interface (step  904   a ). Or, the terminating AS  26   b  can retrieve the HPA subscription  51  from the HSS  50  over the Sh interface when the UE B  24   b  first registers with IMS network  41  (step  904   b ). Alternatively, the terminating AS  26   b  can retrieve the HPA subscription  51  which is stored locally in the terminating AS  26   b  (step  904   c ). At step  906 , the terminating AS  26   b  upon determining that the terminating satellite UE  24   b  has the HPA subscription  51  operates to send the terminating PCRF  42   b  an AAR message to (1) initiate a NRSPCA on Offer to establish a secondary PDP context between the terminating access network  36   b  and the terminating satellite UE  24   b  via the terminating satellite radio access network  34   b , and (2) initiate transmission of a HPA page to the terminating satellite UE  24   b . In one embodiment, the terminating AS  26   b  sends the AAR message to the terminating PCRF  42   b  only if the terminating satellite UE  24   b  has the HPA subscription  51  and a Require header field and a Supported header field in the received SIP INVITE message do not contain preconditions and a Session Description Protocol (SDP) portion of the SIP INVITE message does not contain “desired QoS” and “current QoS.” If desired, the AAR can include an AVP indicating to the terminating PCRF  42   b  that the call requires NRSPCA on Offer such that the PCRF  42   b  delays sending an AAA message back to the AS  26   b  until the PCRF  42   b  receives an indication of a successful secondary PDP context activation from the terminating access network  36   b  (e.g., GGSN  38   b ). The terminating AS  26   b  can also perform other steps which have been described above with respect to  FIG. 5  and  FIG. 6 . 
     Referring to  FIG. 10 , there is a flowchart illustrating a method  1000  which is implemented by a terminating PCRF  42   b  when establishing a call between an originating UE  24   a  and a terminating satellite UE  24   b  in accordance with an embodiment of the present invention. The terminating PCRF  42   a  comprises at least a processor  1001  and a memory  1003  that stores processor-executable instructions where the processor  1001  interfaces with the memory  1003  and executes the processor-executable instructions to enable steps  1002 ,  1004 ,  1006 ,  1008 ,  1010 ,  1012 ,  1014 , and  1016 . At step  1002 , the terminating PCRF  42   a  receives from the terminating AS  26   a  an AAR to initiate a NRSPCA on Offer to establish a secondary PDP context between the terminating access network  36   b  and the terminating satellite UE  24   b  via the terminating radio access network  34   b . At step  1004 , the terminating PCRF  42   a  determines if the AAR indicates the NRSPCA on Offer. If the result of the determine step  1004  is that the AAR does indicate the NRSPCA on Offer, then the terminating PCRF  42   a  performs the following steps: (a) generate charging rules per media component (step  1006 ); (b) obtain QoS information per media component (step  1008 ); (c) initiate the NRSPCA on Offer by sending a RAR message to the terminating access network  36   b  (e.g., GGSN  38   b ) (step  1010 ); (d) wait to receive a RAA message from the terminating access network  36   b  (e.g., GGSN  38   b ) which confirms establishment of the secondary PDP context between the terminating access network  36   b  and the terminating satellite UE  24   b  via the terminating radio access network  34   b  (step  1012 ); (e) upon receipt of the RAA message from the terminating access network  36   b  (e.g., GGSN  38   b ), send an AAA message back to the terminating AS  26   b  (step  1014 ). If the result of the determine step  1004  is that the AAR does not indicate the NRSPCA on Offer, then the terminating PCRF  42   a  sets up a NRSPCA on Answer. The terminating PCRF  42   a  can also perform other steps which have been described above with respect to  FIG. 5  and  FIG. 6 . 
     Referring to  FIG. 11 , there is a flowchart illustrating a method  1100  which is implemented by a terminating satellite RAN  34   b  when establishing a call between an originating UE  24   a  and a terminating satellite UE  24   b  in accordance with an embodiment of the present invention. The terminating satellite RAN  34   b  comprises at least a processor  1101  and a memory  1103  that stores processor-executable instructions where the processor  1101  interfaces with the memory  1103  and executes the processor-executable instructions to enable steps  1102 ,  1104 ,  1106 , and  1108 . At step  1102 , the terminating satellite RAN  34   b  receives from the terminating SGSN  40   b  a HPA message which is to be transmitted to the terminating satellite UE  24   b . At step  1104 , the terminating satellite RAN  34   b  determines if the HPA message indicates that the call is a conversational call or interactive call. If the result of the determine step  1104  is that the HPA message indicates that the call is a conversational call or interactive call, then the terminating satellite RAN  34   b  at step  1106  sends a HPA page  61  to the terminating satellite UE  24   b . If the result of the determine step  1104  is that the HPA message indicates that the call is not a conversational call or interactive call, then the terminating satellite RAN  34   b  at step  1108  sends a non-HPA page to the terminating satellite UE  24   b . The terminating satellite RAN  34   b  can also perform other steps which have been described above with respect to  FIG. 5  and  FIG. 6 . 
     Although multiple embodiments of the present invention have been illustrated in the accompanying Drawings and described in the foregoing Detailed Description, it should be understood that the invention is not limited to the disclosed embodiments, but instead is also capable of numerous rearrangements, modifications and substitutions without departing from the present invention that as has been set forth and defined within the following claims.