PATENT DOCUMENT

Publication Number: US-8363657-B2
Application Number: US-95454707-A
Country: US
Kind Code: B2

Title: SIP-enabled framework for multi-domain roaming control plane in a WiMAX access network

Abstract:
Middleware is provided as a control plane for WiMAX control messaging. Each ASN in a WiMAX system is associated with a Session Initiation Protocol (SIP) server. A plurality of Functional Entities (FEs) are distributed across the ASNs, wherein each FE (or a group of FEs) associated with a SIP agent. Each FE is operable to control a function associated with a subscriber station (SS). The function controlled by a first FE is transferred to a second FE by employing the SIP agents to establish a SIP session between the first and second FEs. WiMAX control messages are then exchanged over the established session to transfer the SS function from the first FE to the second FE. The first and second FEs may be in the same ASN—i.e. the SS mobility is intra-domain—or, the first and second FEs may be in different ASNs—i.e. the SS mobility is inter-domain.

Claims:
1. A broadband network access system comprising:
 one or more Access Service Networks (ASNs), each ASN coupled with a Session Initiation Protocol (SIP) server; 
 a plurality of Functional Entities (FEs) implemented in respective ones of the ASNs, wherein each FE is associated with a broadband network access system control function, each FE controlling a function associated with a respective subscriber station (SS); 
 wherein a first FE controls an SS function of a first SS; 
 a plurality of SIP agents, each SIP agent associated with a FE or a group of FEs; 
 wherein the SIP server coupled with the ASN associated with the first FE, the SIP server coupled with the ASN associated with a second FE, and SIP agents associated with the first and second FEs are configured to establish a SIP session between the first and second FEs; and 
 wherein broadband network access system control messages are exchanged over the established session to transfer the SS function from the first FE to the second FE. 
 
     
     
       2. The broadband network access system of  claim 1  wherein each SIP agent is associated with an API, and wherein the SIP session between the first and second FEs employs the APIs in each of the SIP agents associated with the first and second FEs to establish the SIP session, and exchange of broadband network access system control messages employs the APIs in each of the SIP agents associated with the first and second FEs to transfer the SS function from the first FE to the second FE. 
     
     
       3. The broadband network access system of  claim 1  wherein the SS is a mobile SS, and wherein the first and second FEs are in the same ASN, and wherein the SIP server coupled with the ASN associated with the first FE is the same as the SIP server coupled with the ASN associated with the second FE. 
     
     
       4. The broadband network access system of  claim 1  wherein the SS is a mobile SS, and wherein the first and second FEs are in different ASNs, and wherein the SIP server coupled with the ASN associated with the first FE is different from the SIP server coupled with the ASN associated with the second FE. 
     
     
       5. The broadband network access system of  claim 1  wherein the first and second FEs are radio resource controllers. 
     
     
       6. The broadband network access system of  claim 1  wherein the first and second FEs are handover controllers. 
     
     
       7. The broadband network access system of  claim 1  wherein the first and second FEs are paging controllers. 
     
     
       8. The broadband network access system of  claim 1  wherein the first and second FEs are context exchange controllers. 
     
     
       9. The broadband network access system of  claim 1  wherein the first and second FEs are security controllers. 
     
     
       10. The broadband network access system of  claim 1  wherein the first and second FEs are service flow and data forwarding controllers. 
     
     
       11. The broadband network access system of  claim 1  wherein the SIP session between the first and second FEs comprises a point-to-point SIP session between the first and second FEs. 
     
     
       12. The broadband network access system of  claim 11  wherein exchange of broadband network access system control messages over the established session to transfer the SS function from the first FE to the second FE exchanges control messages over a session established between the first FE and the second FE in a first ASN. 
     
     
       13. The broadband network access system of  claim 11  wherein exchanging exchange of broadband network access system control messages over the established session to transfer the SS function from the first FE to the second FE exchanges control messages over a session established between the first FE in a first ASN and the second FE in a second ASN. 
     
     
       14. The broadband network access system of  claim 1  wherein the SIP session between the first and second FEs comprises a multiparty SIP session between an ASN and a group of FEs including the second FE. 
     
     
       15. The broadband network access system of  claim 14  wherein exchanging exchange of broadband network access system control messages over the established session to transfer SS function from the first FE to the second FE exchanges control messages over a session established between the first FE in a first ASN and exchanges multicast control messages over a multiparty SIP session between a second ASN and a group of FEs including the second FE. 
     
     
       16. A non-transitory computer readable medium having embodied therein a computer program for storing data, wherein the computer program is executable to:
 implementing a plurality of Functional Entities (FEs) on one or more Access Service Networks (ASNs) of a broadband access system, wherein a first FE and a second FE are associated with a broadband network access system control function associated with subscriber stations (SS); 
 transferring of a SS function controlled by a first FE to a second FE, said transferring comprising:
 establishing a SIP session between the first and second FEs, wherein said establishing the SIP session is performed by a SIP server coupled with the ASN associated with the first FE, the SIP server coupled with the ASN associated with the second FE, and SIP agents associated with the first and second FEs; and 
 exchanging broadband network access system control messages over the established SIP session to transfer the SS function from the first FE to the second FE. 
 
 
     
     
       17. The non-transitory computer readable medium of  claim 16  wherein each SIP agent is associated with an API, and wherein the establishing the SIP session between the first and second FEs employs the APIs in each of the SIP agents associated with the first and second FEs to establish the SIP session, and wherein the exchanging broadband network access system control messages employs the APIs in each of the SIP agents associated with the first and second FEs to transfer SS function from the first FE to the second FE. 
     
     
       18. The non-transitory computer readable medium of  claim 16  wherein the SS function is associated with a mobile SS, and wherein the first and second FEs are in the same ASN, and wherein the SIP server coupled with the ASN associated with the first FE is the same as the SIP server coupled with the ASN associated with the second FE. 
     
     
       19. The non-transitory computer readable medium of  claim 16  wherein the SS is a mobile SS, and wherein the first and second FEs are in different ASNs, and wherein the SIP server coupled with the ASN associated with the first FE is different from the SIP server coupled with the ASN associated with the second FE. 
     
     
       20. The non-transitory computer readable medium of  claim 16  wherein the first and second FEs are radio resource controllers. 
     
     
       21. The non-transitory computer readable medium of  claim 16  wherein the first and second FEs are handover controllers. 
     
     
       22. The non-transitory computer readable medium of  claim 16  wherein the first and second FEs are paging controllers. 
     
     
       23. The non-transitory computer readable medium of  claim 16  wherein the first and second FEs are context exchange controllers. 
     
     
       24. The non-transitory computer readable medium of  claim 16  wherein the first and second FEs are security controllers. 
     
     
       25. The non-transitory computer readable medium of  claim 16  wherein the first and second FEs are service flow and data forwarding controllers. 
     
     
       26. The non-transitory computer readable medium of  claim 16  wherein the first control for execution by establishing the SIP session between the first and second FEs comprises establishing a point-to-point SIP session between the first and second FEs. 
     
     
       27. The non-transitory computer readable medium of  claim 26  wherein the second control for exchanging broadband network access system control messages over the established session to transfer SS function from the first FE to the second FE exchanges control messages over a session established between the first FE and the second FE in a first ASN. 
     
     
       28. The non-transitory computer readable medium of  claim 26  wherein the second control for exchanging broadband network access system control messages over the established session to transfer SS function from the first FE to the second FE exchanges control messages over a session established between the first FE in a first ASN and the second FE in a second ASN. 
     
     
       29. The non-transitory computer readable medium of  claim 16  wherein the first control for execution by establishing the SIP session between the first and second FEs establish a multiparty SIP session between an ASN and a group of FEs including the second FE. 
     
     
       30. The non-transitory computer readable medium of  claim 29  wherein the second control for exchanging broadband network access system control messages over the established session to transfer SS function from the first FE to the second FE exchanges control messages over a session established between the first FE in a first ASN and exchanges multicast control messages over a multiparty SIP session between a second ASN and a group of FEs including the second FE. 
     
     
       31. A method comprising:
 implementing a plurality of Functional Entities (FEs) on one or more Access Service Networks (ASNs) of a broadband access system, wherein a first FE and a second FE are associated with a broadband network access system control function associated with subscriber stations (SS); 
 establishing a SIP session between the first FE and the second FE, the session being established by a SIP server coupled with the ASN associated with the first FE, and by the SIP server coupled with the ASN associated with the second FE, and by SIP agents associated with the first and second FEs; 
 exchanging broadband network access system control messages over the established SIP session to transfer an SS function controlled by the first FE to the second FE. 
 
     
     
       32. The method of  claim 31 
 wherein each SIP agent is associated with an API; 
 wherein the establishing the SIP session between the first and second FEs employs the APIs in each of the SIP agents associated with the first and second FEs to establish the SIP session; and 
 wherein the exchanging broadband network access system control messages employs the APIs in each of the SIP agents associated with the first and second FEs to transfer the SS function from the first FE to the second FE. 
 
     
     
       33. The method of  claim 31  wherein the SS function is associated with a mobile SS, and wherein the first and second FEs are in the same ASN, and wherein the SIP server coupled with the ASN associated with the first FE is the same as the SIP server associated with the ASN coupled with the second FE. 
     
     
       34. The method of  claim 31  wherein the SS is a mobile SS, and wherein the first and second FEs are in different ASNs, and wherein the SIP server associated with the ASN coupled with the first FE is different from the SIP server associated with the ASN associated coupled with the second FE. 
     
     
       35. The method of  claim 31  wherein the first and second FEs are radio resource controllers. 
     
     
       36. The method of  claim 31  wherein the first and second FEs are handover controllers. 
     
     
       37. The method of  claim 31  wherein the first and second FEs are paging controllers. 
     
     
       38. The method of  claim 31  wherein the first and second FEs are context exchange controllers. 
     
     
       39. The method of  claim 31  wherein the first and second FEs are security controllers. 
     
     
       40. The method of  claim 31  wherein the first and second FEs are service flow and data forwarding controllers. 
     
     
       41. The method of  claim 31  wherein the establishing the SIP session between the first and second FEs comprises establishing a point-to-point SIP session between the first and second FEs. 
     
     
       42. The method of  claim 41  wherein the exchanging broadband network access system control messages over the established session to transfer SS function from the first FE to the second FE comprises exchanging control messages over a session established between the first FE and the second FE in a first ASN. 
     
     
       43. The method of  claim 41  wherein the exchanging broadband network access system control messages over the established session to transfer SS function from the first FE to the second FE comprises exchanging control messages over a session established between the first FE in a first ASN and the second FE in a second ASN. 
     
     
       44. The method of  31  wherein the establishing the SIP session between the first and second FEs comprises establishing a multiparty SIP session between an ASN and a group of FEs including the second FE. 
     
     
       45. The method of  claim 44  wherein the exchanging broadband network access system control messages over the established session to transfer the SS function from the first FE to the second FE comprises exchanging control messages over a session established between the first FE in a first ASN and exchanges multicast control messages over a multiparty SIP session between a second ASN and a group of FEs including the second FE.

Description:
RELATED APPLICATION 
     This application claims the benefit under 35 U.S.C. 119(e) of U.S. Provisional Patent Application Ser. No. 60/931,355 filed on May 23, 2007 which is hereby incorporated by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to the field of network access, and particularly to mobility and roaming in wireless networks. 
     BACKGROUND OF THE INVENTION 
     In the past, mobile devices such as cell phones were limited to voice service and rudimentary data services. But mobile devices are quickly evolving into full fledged multi-media devices capable of voice service, e-mail service, text messaging, and even video-on-demand. New broadband network access services must be employed to provide the bandwidth and service quality required by these rapidly evolving services. 
     One such broadband network access service is referred to as “WiMAX”. WiMAX is defined as Worldwide Interoperability for Microwave Access by the WiMAX Forum, formed in June 2001 to promote conformance and interoperability of the IEEE 802.16 standard, officially known as WirelessMAN. 
     The WiMAX Forum NWG (network working group) has defined a multi-domain mobility architecture including many functional entities (FEs) to support full mobility and multi-domain roaming within a WiMAX network. But the WiMAX NWG has not yet defined a solution for implementing the communications between FEs that must occur to implement full mobility. One current proposal suggests defining relay, routing, and session management at the FE functional layer. This means IP routing infrastructure and protocols must be reinvented at the application layer, so this is not a practical solution. Another proposal suggests implementing IP multicasting in all nodes. But the gateway and base station portions of an access service node in a WiMAX network are peripheral devices that do not typically implement IP transport functionality such as IP multicast. In order to require such would lead to significantly increased cost for these devices. 
     What is needed is a communication protocol for carrying WiMAX control plane traffic, which preferably provides a low-cost, scalable, interoperable and standard-compliant solution. 
     SUMMARY OF THE INVENTION 
     In accordance with the principles of the invention, middleware is provided as a control plane for WiMAX control messaging. Accordingly, A WiMAX system includes a plurality of Access Service Networks (ASNs). Each ASN associated with a Session Initiation Protocol (SIP) server. A plurality of Functional Entities (FEs) are distributed across the ASNs, wherein each FE is associated with a WiMAX control function. Each FE is also associated with a SIP agent. Each FE is operable to control a function associated with a subscriber station (SS). The SS has a function controlled by a first FE. Logic for the transferring the SS function controlled by the first FE to a second FE includes: logic employed by the SIP server associated with the ASN associated with the first FE, and by the SIP server associated with the ASN associated with the second FE, and by the SIP agents in the first and second FEs for establishing a SIP session between the first and second FEs; and, logic for exchanging WiMAX control messages over the established session to transfer the SS function from the first FE to the second FE. 
     Furthermore, the invention is particularly applicable where the SS is a mobile SS. The first and second FEs may be in the same ASN—i.e. the SS mobility is intra-domain—or, the first and second FEs may be in different ASNs—i.e. the SS mobility is inter-domain. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to facilitate a fuller understanding of the present invention, reference is now made to the appended drawings. These drawings should not be construed as limiting the present invention, but are intended to be exemplary only. 
         FIG. 1  is a representation of a multi-domain WiMAX network in which the invention can be employed. 
         FIG. 2  is a reference model of a WiMAX network as defined by the WiMAX NWG. 
         FIG. 3  shows two ASN profiles as defined by the WiMAX NWG. 
         FIG. 4  is a representation of a multi-domain WiMAX network incorporating the invention. 
         FIG. 5  is a flow diagram of the invention. 
         FIG. 6  is a representation of a first embodiment of the invention as embodied inter-domain and intra-domain, wherein an MS roams between BS. 
         FIG. 7  is a second embodiment of the invention, wherein an MS is paged. 
         FIG. 8  is a working flow diagram of the embodiment of  FIG. 7 . 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     In  FIG. 1  there is shown an exemplary WiMAX network  10  in which the invention can be implemented. The network includes a master access services network (ASN) gateway  12 , which could also be a customer service network (CSN), coupled to multiple access services networks (ASNs)  14 ,  16 ,  18 , also referred to as “domains”. Each ASN  14 ,  16 ,  18  includes an ASN gateway  20 ,  22 ,  24 . Multiple base stations (BS)  26   a  . . . n,  28   a  . . . n,  30   a  . . . n are coupled to the respective ASN gateways  20 ,  22 ,  24 . A mobile station (MS)  32 , such as a cell phone in a car, or a laptop traveling on a train, etc., is coupled to a base station on an ASN, for example the base station  26   a  on the ASN  14 . The base station  26   a  maintains the radio connectivity and data exchange operations between the MS  32  and the ASN  14 . As the MS  32  moves, a hand-off of radio control operations may occur between the BS  26   a  and another BS  26  in the ASN  14 . This may be a “fast handover” between BS, as shown by line R8, or it may be a handover involving the ASN gateway  20  via network R6. Depending on how long, or in what direction, the MS continues to move, a handoff may need to occur from a BS in one ASN to a BS in another ASN. For instance, a handover from the BS  26   a  to the BS  28   a  may occur involving the ASN gateway  20  and  22  over network R4. Also, a handoff may need to occur from a BS in one ASN to a BS in another ASN involving the master ASN gateway  12 . For instance, a handover from the BS  26   a  to the BS  30   a  may occur involving the ASN gateway  20  and the master ASN gateway  12  over to the ASN gateway  24  to the BS  30   a  over network R3. 
     The WiMAX network described above is a “flat” network. That is, the network is non-hierarchical and all network entities are IP entities. But as can be seen, the control plane in the WiMAX network must be dynamically adjustable in order to accommodate mobile stations. That is, when the MS  32  moves from the ASN  14  domain to the ASN  18  domain, certain control functions must move with it. WiMAX defines control messages to be exchanged between the various control entities in the network to support continuous data connectivity for the MS  32 , but WiMAX does not define the manner in which these control messages should be transferred between these entities. In accordance with the invention, there is provided middleware for establishing a control plane for the exchange of these control messages. 
     In  FIG. 2  there is shown a reference model of a WiMAX network  100  as defined by the WiMAX NWG. A WiMAX network  100  includes a NAP  102  having ASNs  104   a  . . .  104   n  interfaced via an “R4” defined network interface. Each ASN  104   a  . . . n includes BS  106   a  . . . n coupled via defined network interface “R8”. The BS are coupled to an ASN gateway  108  via defined network interface “R6”. Each ASN  104  is coupled to a home network service point (NSP)  110  or a visited NSP  110 . Each NSP includes a customer service network (CSN)  112 . ASNs  104  are coupled to CSNs  112  via defined network interface “R3”. CSNs  112  are coupled to each other via defined network interface “R5”. CSNs may be further coupled to the Internet  114 . 
     When the mobile station moves, it may move via a “fast hand-over” between BS  106  within a single ASN  104  via network interface “R8”. Or, it may move “roam” between BS in a single ASN  104  via a radio control anchorpoint in an ASN gateway  108  via network interface “R6”. Or, it may move via different ASNs  104 , but still in the same CSN  112 , via network interfaces “R4, R6”.”. Or, it may move via different ASNs  104 , via the CSN  112 , via network interfaces “R3, R4, R6”. Or, it may move to a different BS  106  on a different ASN on a different CSN, via network interfaces “R5, R3, R4, R6”. The invention described herein operates on network interfaces R3, R4, R5, and R6. 
     Also shown in  FIG. 2  are “Functional Entities” (FEs)  150 . WiMAX FEs  150  are distributed amongst the various network elements (e.g. BS, ASN, ASN gateway, CSN) based on their role assignment (controller/agent, anchor/peer, serving/target) and location (intra-domain or inter-domain). Examples of FEs include security FE  150   a , paging FE  150   b , radio resource FE  150   c , MIP FE  150   d , Name/Address FE  150   e , Service Flow FE  150   f , Location FE  150   g , Handover FE  150   h , policy/QoS FE  150   i , AAA FE  150   j , and Context FE  150   k.    
     Referring now to  FIG. 3 , there are shown ASN profiles as defined by the WiMAX specification, Profile A ( 200 ) and Profile C ( 202 ). The Profile C ASN  202  includes an ASN gateway  204  and three BS  206   a ,  206   b ,  206   c . In Profile C, radio resource management is distributed. Each BS a, b, c includes all the FEs of a radio resource controller  208   a , b, c and agent  210   a , b, c respectively. This results in complexity of implementation, and thus expense, for the BS. But fast handovers can be performed between the BS when an MS roams between them. However, when an MS needs to roam to a BS attached to another ASN, the handover will involve the gateway  204 . 
     The Profile A ASN  200  includes an ASN gateway  220  and three BS  222   a ,  222   b ,  222   c . The ASN gateway  220  includes RRC (radio resource control) Anchor FE  224 , PG (paging control) Anchor  226 , and HO (handover) Anchor  228 . The BS  222   a  includes a corresponding RRC agent  230   a , a PG agent  232   a , and an HO agent  234   a . Likewise, the BS  222   b  includes a corresponding RRC agent  230   b , a PG agent  232   b , and an HO agent  234   b . The BS  222   c  includes a corresponding RRC agent  230   c , a PG agent  232   c , and an HO agent  234   c . This arrangement makes the BS easier and cheaper to implement and is adapted more easily to a multi-vendor environment. In this arrangement, when an MS roams between a BS in the ASN  200 , it must do so via the ASN anchor gateway  220 . 
     In the Profile A case, as a mobile station moves between intra-domain BS, control functions need to move with the mobile station to different FEs in the same ASN. In the Profile C case, as a mobile station moves between BS inter-domain, control functions need to move with the mobile station to different FEs in different ASN. In either case, the target FEs are non-deterministic due to the randomness of the mobile station&#39;s movement, and the movement may occur across multiple domains (i.e. ASNs). Thus, in accordance with the invention, there is provided a communication mechanism between FEs over which WiMAX control messages may be exchanged. It functions between inter- and intra-domain FEs. It is able to dynamically create sessions between FEs in order to respond to the non-deterministic motion of mobile stations. It provides multicast capability for paging, handover, and radio resource management, since multiple BS must be notified of the possible need to support an incoming mobile station. In accordance with advantages of the invention, the communication solution is a middleware solution that supports auto discovery, session management, and call relay. The middleware is scalable, standard-compliant, and infrastructure transparent. 
     Referring to  FIG. 4 , there is shown an embodiment of the invention. A Light-weight SIP protocol is used for session communication between FEs. Depicted are two ASNs, ASN  300  and ASN  350 . ASN  300  includes a SIP server  302  and three BS, BS  304 ,  306 , and  308 . The BS  304  includes an FE or group of FEs, herein shown as an RRC, with a SIP agent (also known as a SIP client)  310 . The BS  306  likewise includes an RRC with a SIP agent  312 , and the BS  308  includes an RRC with a SIP agent  314 . The SIP agents  310 ,  312 ,  314  communicate with the SIP server  302 . 
     Likewise, ASN  350  includes a SIP server  352  and three BS, BS  354 ,  356 , and  358 . The BS  354  includes an FE or group of FEs, herein shown as an RRC, with a SIP agent  360 . The BS  356  likewise includes an RRC with a SIP agent  362 , and the BS  358  includes an RRC with a SIP agent  364 . The SIP agents  360 ,  362 ,  364  communicate with the SIP server  352 . 
     Interdomain, within ASN, SIP agents  310 ,  312 ,  314  register with the SIP server  302 , or an auto-discovery algorithm is used by the SIP server  302  to identify agents coupled to it. Within ASN  350 , SIP agents  360 ,  362 , and  364  register with the SIP server  352  in the same manner. Intra-domain, ASN SIP servers  302  and  352  can set up and tear down SIP sessions between themselves. 
     Now an FE in one domain can exchange WiMAX control messages with an FE in another domain, for instance in anticipation of a roaming event. For example, the RRC  310  in the BS  304  in the ASN  300  can send WiMAX control messages to the RRC  364  in the BS  358  in the ASN  350 , as shown via the heavy line from BS  304  to BS  358 , by sending WiMAX control messages over a TCP/UDP connection between the IP RRCs. The WiMAX control messages are sent via a SIP session that has been set up between SIP agent  310 , SIP server  302 , SIP server  352 , and SIP agent  358 . When the RRCs  310  and  364  communication is complete, the SIP session can be torn down. 
     Generally, SIP is used to manage unicast and multicast sessions between FEs in order to provide a “control plane for the control plane”. SIP sessions are set up and torn down between FEs as a mobile station moves. The SIP sessions serve as the control plane over which the FEs send their WiMAX control messages. Thus, control between FEs can be adjusted as the mobile station moves. Intra-domain, in a Profile C type or in a Profile A type ASN wherein Anchor FEs are used, control can be transferred from one FE in a BS to another FE in a BS over a TCP/UDP connection between the FEs over an R6 network interface. WiMAX control messages are relayed via SIP sessions maintained between the FEs and the SIP server. Inter-domain, an FE in one domain (ASN) can exchange WiMAX control messages with an FE in another domain (As shown in  FIG. 4  via line from BS  302  to BS  358 ) by sending the control messages over a TCP/UDP connection over an R4 or R3 interface. 
     Light Weight SIP is a convenient protocol for use in that it is a standard compliant protocol; thus it offers ease of interoperability. SIP is implemented as middleware; thus, it is ASN infrastructure transparent. That is, the SIP sessions are agnostic to the underlying ASN access technology, be it IP, Ethernet, MPLS, etc. 
     In particular, in order to implement the invention, each FE (or FE group) is built with an embedded SIP agent ( FIG. 4 , RRCs with SIP agents  310 ,  312 ,  314 ,  360 ,  362 ,  364 ). A SIP proxy server is installed for each ASN control plane—i.e. for each domain. “Lightweight” SIP—that supporting text only, without support for multimedia streams—is sufficient for use for purposes of the invention. It will be helpful to extend SDP (IETF RFC 3312/3313) to include bandwidth, tunnel-end address, and tunnel ID for tunnel management (e.g., IP GRE, E-VLAN, MPLS PW). The FE (or FE group) registers to the SIP server with a URL address and an IP address. As shown in  FIG. 4 , each SIP agent has an API associated with it. APIs  370 ,  372 ,  374 ,  375 ,  377 , and  379  are associated with SIP agents  310 ,  312 ,  314 ,  360 ,  362 ,  364  respectively. The APIs are provided by the SIP agents and used by FEs to communicate with each other. Each FE calls its SIP agent via its SIP agent&#39;s respective API. In turn, the SIP agents use a SIP stack to create, change, and maintain unicast or multicast point-to-point sessions dynamically. SIP multi-party sessions are used for multicasting control traffic to support anchoring functions such as paging and RRM spare capacity request. The session can be pre-configured or set up on demand. All WiMAX control messages can be implemented in the known manner using HTTP, Servlet, CGI, or SOAP over the sessions, and can be transmitted over TCP/UDP ports. 
     In  FIG. 5  there is shown a flow diagram of the steps of the invention. It may be determined that FEs need to exchange WiMAX control messages—because an MS is moving and radio resources must be adjusted, or because an MS has moved while it was sleeping and must be located for data forwarding, etc. When control messages need to be exchanged between FEs, (step  380 ), the SIP servers and agents in the ASNs associated with the FEs establish SIP sessions (step  382 ). In some cases, these SIP sessions may already be established. In others, they may need to be established on demand. Once a SIP session is established between the FEs, the WiMAX control messages are exchanged via TCP or UDP messaging over IP (step  384 ). Once the message exchange is complete, the session may be torn down (step  386 ). 
     Referring to  FIG. 6 , there is shown an example WiMAX network wherein SIP sessions are set up between FEs for WiMAX control message exchange. An ASN  400  and ASN  450  are shown. ASN  400  includes gateway (GW)  402  and BS  404 ,  406 , and  408 . BS  404  includes radio resource management agents and controllers  410 ,  412 . Likewise, BS  406  includes radio resource management agents and controllers  414 ,  416 , and BS  408  includes radio resource management agents and controllers  418 ,  420 . The GW includes a radio resource control anchor  422 , designated as anchor for inter-domain mobility. ASN  400  further includes SIP server  424 . All of the FEs in the ASN  400 , including the RRCs  416 ,  418 , and  422 , have registered their URLs and IP names with the SIP server  424 . 
     ASN  450  is configured similarly to ASN  400 . ASN  450  includes gateway (GW)  452  and BS  454 ,  456 , and  458 . BS  454  includes radio resource management agents and controllers  460 ,  462 . Likewise, BS  456  includes radio resource management agents and controllers  464 ,  466 , and BS  458  includes radio resource management agents and controllers  468 ,  470 . The GW includes a radio resource control anchor  472 , designated as anchor for inter-domain mobility. ASN  450  further includes SIP server  474 . All of the FEs in the ASN  450 , including the RRCs  466 ,  468 , and  472 , have registered their URLs and IP names with the SIP server  474 . 
     An MS  480  is shown as its network connectivity moves from BS  406  to BS  408  in ASN  400 , and then over to BS  454  in ASN  450 . When the MS moves from BS  406  to BS  408 , or when such a move is indicated or anticipated, a SIP session request is sent from RRC  416  to SIP server  424  via link  482 , SIP server  424  then forwards it to RRC anchor  422  via link  488 , thus a session is established between the RRC FE  416  in the BS  406  and the RRC anchor  422  in the ASN GW  402 . Accordingly, a second SIP session  484  is established between the RRC anchor  422  and the RRC FE  420  in the BS  408  via link  488  and  484 , and a third SIP session is established between RRC  416  and RRC  420  via link  482  and  484 . Once these SIP sessions are established among the various RRCs, they can exchange control messages for radio resource management. For example, after the SIP session between the RRC  416  and RRC  420  is established, WiMAX TCP/UDP control messages  486  are sent from the RRC  416  to the RRC  420 , with the coordination from the RRC anchor  422  via the network interface R6 to ultimately switch radio resource control for the MS  480  to the BS  408 . 
     When the MS moves from the BS  408  to the BS  454 , WiMAX control messages are sent to transfer radio resource control from the RRC  420  in the BS  408  to the RRC  462  in the BS  454 . In order to establish a control path for these messages, a SIP session  496  is established (if not already maintained) between the RRC FE  420  in the BS  408  located at ASN  400  and RRC  462  in the BS  454  located at ASN  450 . The SIP signaling procedures involve RRC  420  as source entity, RRC  462  as destination entity, and SIP server  424  in ASN  400  and SIP server  474  in ASN  450  to relay the SIP messages, via the link  484  in ASN  400 , the link  494  between SIP server  424  and  474 , and the link  490  in ASN  450 . In this manner, a control plane is established and maintained so that WiMAX control messages over session  496  can be sent via TCP/UDP from the RRC  420  in the BS  408  in the ASN  400  to the RRC  462  in the BS  454  in the ASN  450  with the coordination of the RRC anchors  422 ,  472  via the network interface R4. 
     Meanwhile, as the MS  480  moves across domains, the RRC anchor  422  sends WiMAX control messages containing MS  480  information to the neighboring ASN  450 , and sends WiMAX control messages inquiring of the neighboring ASN  450 &#39;s radio channel availability via the R4 network interface. These WiMAX control messages are sent via the SIP session that is maintained between the RRC anchor  422  and the RRC anchor  472  in the GW  452 . One such message may be an “RRM spare capacity request” message. This is a multicast message that addresses many BS to see which BS are available to service an incoming MS. In order to transport this message, a multi-party SIP session is set up by the SIP server  474  in the ASN  450  among all the RRCs  472 ,  462 ,  466 ,  470  so that the RRC anchor  472  can send the RRM spare capacity request multicast message to all the RRCs  462 ,  466 , and  470  in the respective BS  454 ,  456 , and  458 . 
     Referring now to  FIG. 7 , there is shown another WiMAX network example wherein WiMAX control messages are exchanged between FEs via SIP sessions. In this example, data needs to be sent from a home network (not shown) to a sleeping mobile subscriber station. Again, in a WiMAX network, the location of a mobile subscriber station is non-deterministic because the station can move between BS, ASNs, and/or CSNs while asleep. When data arrives for a sleeping MS, WiMAX buffers the data and uses a paging mechanism to discover the location of the sleeping MS. 
     In  FIG. 7  there is shown a master ASN GW  502  coupled via R3 network interfaces to multiple ASNs  504 ,  506 , and  508 , each including ASN GW  510 ,  512 , and  514  respectively. The ASN GWs  510 ,  512 , and  514  are peers coupled via R4 network interfaces. Each ASN GW  510 ,  512 , and  514  is coupled via R6 network interfaces to a set of BS. ASN GW  510  is coupled to BS  516 ,  518 . ASN GW  512  is coupled to BS  520 ,  522 . ASN GW is coupled to BS  524 ,  526 . BS  520  is shown coupled to multiple MS  528   a, b, c . Likewise, BS  522  is shown coupled to multiple MS  530   a, b, c.    
     The master ASN GW  502  is shown to include a SIP server  534 . The ASN GW  510  includes a SIP server  536 . The ASN GW  512  includes a SIP server  538 . The ASN GW  540  includes a SIP server  540 . Each BS is also shown to include an FE having a SIP agent. Each BS may include more than one FE/SIP agent, one being shown here for clarity of description. The BS  516  includes SIP agent  542 . The BS  518  includes SIP agent  544 . The BS  520  includes SIP agent  546 . The BS  522  includes SIP agent  548 . The BS  524  includes SIP agent  550 . The BS  526  includes SIP agent  552 . 
     The SIP agents  542  and  544  have registered a URL and IP name with the SIP server  536  in the ASN GW  510 . Likewise, the SIP agents  546  and  548  have registered a URL and IP name with the SIP server  538  in the ASN GW  512 , and the SIP agents  550  and  552  have registered a URL and IP name with the SIP server  540  in the ASN GW  514 . In turn, each ASN SIP server  510 ,  512 , and  514  has registered its URL and IP name with the SIP server  534  in the Anchor ASN  502 . SIP sessions can now be set up and torn down between any client server pair in order that WiMAX control messages can be passed between FEs. 
     In  FIG. 7 , there is also shown DP/FA controller  568  and anchor PC/LR controller in Master ASN GW  502 ; PC controller  570 ,  554  and  572  in ASN  510 , ASN  512 , and ASN  514 ; and PC agents  574 ,  576 ,  578  and  580  in BS  516 ,  518 ,  520  and  522 . In  FIG. 7 , DP/FA controller  568  is for payload data management and forwarding, and all PC controllers and agents are for paging management. 
     Now, referring to  FIGS. 8 and 7 , the WiMAX control message flow is shown. Downlink data is received from a home agent (label “1”), destined for the MS  530   b , while the MS  530   b  is asleep. The anchor datapath FE  568  in the master ASN GW  502  receives and buffers the data, recognizes that the MS  530   b  is in Idle mode, and then sends an MS info request to the Paging controller FE  556  to locate the MS (label “2”). The paging controller FE  556  in the ASN GW  502  confirms the request indicating that the MS is authorized for service (label “3”). Paging controller  556  figures out which paging group the MS  530   b  is in (in this example the paging group may include ASN  504  and ASN  506 ), and then retrieves the MS paging info (comprising PGID, paging cycle, paging offset, a relay PCID, or a set of BSIDs including the last reported one) and constructs a Paging Announce message. The paging controller FE  556  in the ASN GW  502  then sends a multicast paging message to all the paging controllers in both ASN  504  and ASN  506  based on its knowledge of the topology of the Paging region. For the received paging announce message, in turn, paging controller  570  in ASN GW  510  and paging controller  554  further multicast the message to all the BS (paging agent  574 ,  576 ,  578  and  580  at BS  516 ,  518 ,  520 ,  522 ) in the paging group (label “4”). The MS is then notified by the BS to which it is attached that there is data waiting for it (label “5”). 
     In accordance with the invention, in order for the datapath FE  568  to send the MS info Request to the paging controller FE  556 , a SIP session is established between the FEs  554  and  556 . 
     Once the session setup is complete, the MS info Request message is relayed via TCP/UDP accordance with the invention from the data path FE  568  to the paging controller FE  556  in the master ASN GW  502  ( FIG. 8  label “2” and label “3”) indicating which paging group the MS is in and if the MS is authorized. 
     As well, to enable master anchorPC controller  556  to send multicasting paging announcement messages to all the PC agents in the paging group, multi-party sessions need to be established from master anchor PC controller to all relay PC controllers such as PC FE  570  and PC FE  554 . In turn, PC FE  570  and  554  will also need to establish the multi-party session to all the PC agents in each BS. 
     In order for the Paging controller FE  556  in the ASN GW  502  to send the multicast paging announcement message to all BS included in the paging group that includes the MS, a multi-party SIP session is established among the master paging controller  556  and relay PC controllers  570  and  554  via SIP server  534 ,  536  and  538 . In turn, PC FE  570  and  554  will also need to establish the multi-party session to all the PC agents in each sub-paging-group such as  574 ,  576 ,  578  and  580  in the BS  516 ,  518 ,  520  and  522  via SIP server  536  and  538 , respectively ( FIG. 7   564  and  FIG. 7   566 ). 
     After all the sessions are established (if they did not exist before), the paging controller FE  556  in the ASN GW  502  can then send a multicast TCP paging message to all the SIP agents ( 546 ,  548 ) in the paging group (label “4”). The BS  522  to which the targeted MS is attached can then broadcast page messages to its attached MS  530   a, b, c.    
     The present invention is not to be limited in scope by the specific embodiments described herein. Various modifications of the present invention, in addition to those described herein, will be apparent to those of ordinary skill in the art from the foregoing description and accompanying drawings. One skilled in the art will understand that many specific implementations can be employed to achieve the logical functionality of the invention. All such modifications are intended to fall within the scope of the invention. Software maybe embodied on any known non-transitory computer readable medium having embodied therein a computer program for storing data. In the context of this document, a computer readable medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. A computer readable medium may be, for example, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the computer readable medium would include the following: a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. Further, although aspects of the present invention have been described herein in the context of a particular implementation in a particular environment for a particular purpose, those of ordinary skill in the art will recognize that its usefulness is not limited thereto and that the present invention can be beneficially implemented in any number of environments for any number of purposes.

Metadata:
Filing Date: 20071212
Publication Date: 20130129
Grant Date: 20130129
Priority Date: 20070523
Inventors: WANG GUO QIANG
Assignee: APPLE INC
CPC Classifications: [{"code": "H04W80/10", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04L65/1104", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04L65/1104", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W80/10", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04L65/1083", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W80/10", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04L65/1083", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04L65/1083", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 40075511