IP-Based Next-Generation Wireless Networks phần 5 doc

the SDP received from the destination mobile. Finally the destination mobile responds to the confirmation with an acknowledgment (Conf ACK). After that, the mobile issues a Reservation Confirmation (Reservation Conf) message, which completes the resource reservation. Please refer to Chapter 6 for issues related to QoS (Quality of Service) and resource reservation indicated in Figures 3.15 –3.17. The destination mobile is alerted by the incoming request by a ringing indication. The originating mobile may also hear the ring-back tone and is alerted that the destination is ringing. Once the destination mobile user answers the request, a SIP 200 OK message is returned to the originating user, which then responds with a SIP ACK message. In Figures 3.15 –3.17, the dotted-rectangular represents two optional flows. That is, the flow may be relayed by the I-CSCF or it may bypass the I-CSCF. Although we explain the end-to-end session setup by Figures 3.15–3.17 altogether, each of the figures is independent and can be combined with other procedures. For instance, the S-CSCF to S-CSCF signaling flow of Figures 3.16 could be used with other Fig. 3.16 S-CSCF to S-CSCF signaling flow 152 IP MULTIMEDIA SUBSYSTEMS AND APPLICATION-LEVEL SIGNALING mobile origination flows and mobile termination flows, in which the originating or destination mobile user is in its own home network. It is also possible that the flow is initiated or terminated from PSTN or PLMN. The releas e of a session is normally initiated by a mobile. During the session release process, the related bearers are deleted and necessary billing information is Fig. 3.17 Mobile termination flow 3.2 3GPP IP MULTIMEDIA SUBSYSTEM (IMS) 153 collected by the network. The session release may also be initiated by the network due to loss of radio connection, loss of IP bearer, operator intervention, etc. Figure 3.18 depicts a normal termination of SIP session initiated by mobile user. Once a mobile user hangs up, the mobile station generates a SIP BYE message, which is delivered all the way to the other mobile party via various components such as P-CSCF, and S-CSCF. Related resources are removed, and service control logics are executed when receiving the SIP BYE message. Once the destination mobile receives the BYE message, it responds with a 200 OK message back to the originating mobile. Although network-initiated session termination is not discussed in this section, it is similar to mobile-initiated session termination. The major difference is who initiates the SIP BYE message. 3.3 3GPP2 IP MULTIMEDIA SUBSYSTEM (IMS) 3GPP2 is currently defining an IP Multimedia Subsystem (IMS), which is a subsystem of 3GPP2 IP Multimedia Domain (MM D). Most of the 3GPP2 IMS specifications are still in draft status. Many of them are based on the specifications of 3GPP IMS. Becaus e the signaling flows in 3GPP2 IMS essentially are the same as those in 3GPP IMS, this section only reviews the 3GPP2 IMS architecture. The system requirements of 3GPP2 MMD are specified in [3]. The MMD system consists of a mobile station, radio access network, and core network. It provides end-to-end IP connectivity, services, and features through the core network to subscribers. To enable independent evolution of core network and radio access network, the core network should be able to connect with various types of radio access networks by standard protocols. The MMD system is backward compatible with the legacy packet system specified in 3GPP2 P.S0001 [1], although the MMD system could be built without the legacy packet system. Figure 3.19 depicts the MMD core network architecture that is capable of providing Packet Data Subsystem (PDS) and IMS [4]. The collection of components that supports general packet data services is called PDS. The IMS comprises the entities that provide multimedia session capabilities. The IMS is further illustrated in Figure 3.20. Most components and interfaces in Figure 3.20 are basically the same as those defined in 3GPP IMS. In Figure 3.20, the combina tion of the AAA and various databases provides the functionality of the HSS (Home Subscriber Server). Please be advised that some network entities shown in Figure 3.19 are common to both PDS and IMS. Figure 3.21 illustrates the service control of 3GPP2 MMD. Same as that in 3GPP, the CSCF (Call Session Control Function) is a SIP server and the ISC (IMS Service Control) interface is based on SIP. Compared with Figure 3.7 in 3GPP, the Application Server A and the Application Server B in Figure 3.21 essentially are the OSA Application Server and the SIP Application Server in Figure 3.7, respectively. There is no CAMEL service in 3GPP2. The Application Server C in Figure 3.21 represents generic applications that only utilize bearer resources. The Position Server could provide geographic position information. The combination of 154 IP MULTIMEDIA SUBSYSTEMS AND APPLICATION-LEVEL SIGNALING Fig. 3.19 3GPP2 MMD core network architecture Fig. 3.18 Release flow: mobile initiated 3GPP2 IP MULTIMEDIA SUBSYSTEM (IMS) 155 Fig. 3.20 3GPP2 IMS architecture Fig. 3.21 3GPP2 IMS service platforms 156 IP MULTIMEDIA SUBSYSTEMS AND APPLICATION-LEVEL SIGNALING the position server with the AAA and OSA service capability server is responsible for ensuring proper authorization for access request from every position. Details were still under development by 3GPP2 at the time this book was completed. Figure 3.22 shows a functional architecture providing SIP-based multimedia services. A mobile station should perform SIP registration with the P-CSCF in the visited network before it can acce ss any service provided by the IMS. The necessary authentication would be carried out by the local AAA server. Once authorized by the visited network, the mobile station could further connect to the S-CSCF in the home network. Same as that in 3GPP, the home network may leverage the I-CSCF to hide internal configuration. Session control such as registration, initiation, and termination is based on SIP. Details of signaling flows are presented in 3GPP2 X.P0013.2 [2], which is based on 3GPP TS 23.228 [10]. This section does not discuss the detailed flows because most of them are the same as those pres ented in Sections 3.2.5 –3.2.7. Fig. 3.22 3GPP2 IMS service control 3GPP2 IP MULTIMEDIA SUBSYSTEM (IMS) 157 To conclude this chapter, we point out that 3GPP and 3GPP2 are harmonizing their IMSs. In addition, 3GPP is integrating WLAN as well [7], [9]. It is expected that a common IMS would work over cdma2000, WCDMA, and WLAN. REFERENCES 1. 3rd Generation Partnership Project 2 (3GPP2). Wireless IP network standard. 3GPP2 P.S0001, Version 1.0, December 1999. 2. 3rd Generation Partnership Project 2 (3GPP2). All-IP multi-media domain; IP multimedia subsystem; stage 2. 3GPP2 X.P0013.2, Version 1.6.0, March 2003. 3. 3rd Generation Partnership Project 2 (3GPP2). IP Multimedia Domain; System Requirements. 3GPP2 S.P0058, Version 0.5.4, February 2003. 4. 3rd Generation Partnership Project 2 (3GPP2). IP network for cdma2000 spread spectrum systems; 3GPP2 all-IP core network; enhancements for multimedia domain (MMD); overview (part-00). 3GPP2 X.P0013.0, Revision 0.22, March 2003. 5. 3rd Generation Partnership Project (3GPP), Technical Specification Group Core Network. Application programming interface (API); part 1: overview, release 5. 3GPP TS 29.198-1, Version 5.1.1, March 2003. 6. 3rd Generation Partnership Project (3GPP), Technical Specification Group Core Network. CAMEL application part (CAP) specification, release 5. 3GPP TS 29.078, Version 5.3.0, March 2003. 7. 3rd Generation Partnership Project (3GPP), Technical Specification Group Services and System Aspect. Feasibility study on 3GPP system to wireless local area network (WLAN) interworking, release 6. 3GPP TR 22.934, Version 6.1.0, December 2002. 8. 3rd Generation Partnership Project (3GPP), Technical Specification Group Services and System Aspect. Service requirements for the IP multimedia core network subsystem, release 5. 3GPP TS 22.228, Version 5.6.0, June 2002. 9. 3rd Generation Partnership Project (3GPP), Technical Specification Group, Services and System Aspects. 3GPP system to wireless local area network (WLAN) interworking; functional and architectural definition. 3GPP TR 23.934,Version 1.0.0, August 2002. 10. 3rd Generation Partnership Project (3GPP), Technical Specification Group, Services and System Aspects. IP multimedia subsystem (IMS) stage 2, release 5. 3GPP TS 23.228, Version 5.7.0, December 2002. 11. 3rd Generation Partnership Project (3GPP), Technical Specification Group, Services and System Aspects. Network architecture, release 5. 3GPP TS 23.002, Version 5.7.0, June 2002. 12. H. Schulzrinne. RTP profile for audio and video conferences with minimal control. IETF RFC 1890, January 1996. 13. H. Schulzrinne, S. Casner, R. Frederick, and V. Jacobson. RTP: a transport protocol for real-time applications. IETF RFC 1889, January 1996. 14. T. Berners-Lee, R. Fielding, and L. Masinter. Uniform resource identifiers (URI): generic syntax. IETF RFC 2396, August 1998. 15. B. Campbell, J. Rosenberg, H. Schulzrinne, C. Huitema, and D. Gurle. Session initiation protocol (SIP) extension for instant messaging. IETF RFC 3428, December 2002. 158 IP MULTIMEDIA SUBSYSTEMS AND APPLICATION-LEVEL SIGNALING 16. D.L. Mills. Network time protocol (version 3): specification, implementation and analysis. IETF RFC 1305, March 1992. 17. T. Dierks and C. Allen. The TLS protocol. IETF RFC 2246, January 1999. 18. R. Droms. Dynamic host configuration protocol. IETF RFC 2131, March 1997. 19. M. Handley and V. Jacobson. SDP: session description protocol. IETF RFC 2327, April 1998. 20. ITU-T Rec. H.248. Gateway control protocol, June 2000. 21. ITU-T Rec. H.323. Packet-based multimedia communications systems, November 2000. 22. R. Stewart, Q. Xie, K. Morneault, C. Sharp, H. Schwarzbauer, T. Taylor, I. Rytina, M. Kalla, L. Zhang, and V. Paxson. Stream control transmission protocol. IETF RFC 2960, October 2000. 23. A.B. Roach. Session initiation protocol (SIP)—specific event notification. IETF RFC 3265, June 2002. 24. J. Rosenberg. The session initiation protocol (SIP) UPDATE method. IETF RFC 3311, September 2002. 25. J. Rosenberg and H. Schulzrinne. An offer/answer model with the session description protocol (SDP). IETF RFC 3264, June 2002. 26. J. Rosenberg and H. Schulzrinne. Reliability of provisional responses in the session initiation protocol (SIP). IETF RFC 3262, June 2002. 27. J. Rosenberg, H. Schulzrinne, G. Camarillo, A. Johnston, J. Peterson, R. Sparks, M. Handley, and E. Schooler. SIP: session initiation protocol. IETF RFC 3261, June 2002. 28. J. Rosenberg, H. Schulzrinne, G. Camarillo, A. Johnston, J. Peterson, R. Sparks, M. Handley, and E. Schooler. SIP: session initiation protocol. IETF RFC 3261, June 2002. 29. S. Donovan. The SIP INFO method. IETF RFC 2976, October 2000. 30. H. Schulzrinne and J. Rosenberg. A comparison of SIP and H.323 for Internet telephony. In Proc. of Network and Operating Systems Support for Digital Audio and Video (NOSSDAV), Cambridge, England, July 1998. 31. R. Sparks. The SIP refer method. IETF Internet Draft, kdraft-ietf-sip-refer-07.txtl, work in progress, November 2002. 32. A. Vaha-Sipila. URLs for telephone calls. IETF RFC 2806, April 2000. REFERENCES 159 4 Mobility Management This chapter examines methodologies for supporting mobility in wireless IP networks. We begin by discussing the basic issues in mobility management, including the impact of naming and addressing on mobility management, location management, and handoffs. Then, we will focus on mobility management methodologies for IP networks, 3GPP packet networks, 3GPP2 packet networks, and MWIF networks. 4.1 BASIC ISSUES IN MOBILITY MANAGEMENT Mobility can take different forms such as follows: . Terminal mobility: Terminal mobility is the ability for a user terminal to continue to access the network when the terminal moves. . User mobility: User mobility is the ability for a user to continue to access network services under the same user identity when the user moves. This includes the ability for a user to access network services from different terminals under the same user identity. . Service mobility: Service mobility is the ability for a user to access the same services regardless of where the user is. Mobility can be discrete or continuous. Take terminal mobility, for example; discrete terminal mobility is the ability for a terminal to move to a new location, IP-Based Next-Generation Wireless Networks: Systems, Architectures, and Protocols, By Jyh-Cheng Chen and Tao Zhang. ISBN 0-471-23526-1 # 2004 John Wiley & Sons, Inc. 161 [...]... location updates They can be classified into the following categories [11], [54 ], [51 ]: Time-based update [11], [54 ]: A mobile performs location update periodically at a constant interval (called the update interval) Time-based location update is often used as a backup to other location update strategies Movement-based update [11], [54 ], [13]: A mobile performs a location update whenever it traverses a... unique advantages, but also it has its limitations Movement-based strategies with a movement threshold of one and timebased strategies are the most commonly used strategies in existing wireless networks and in 3G wireless networks (e.g., 3GPP and 3GPP2) Selection of location update strategies should be considered in concert with paging strategies (Section 4.1.2.2) as they are closely related to each other... channels from one base station to another or from one radio frequency band to another on the same base station Handoff in an IP-based wireless network is a much broader issue than the changing of a mobile’s radio channels from one base station First, handoffs in an IP-based wireless network may occur at different protocol layers: Physical Layer: During a physical layer handoff, a mobile changes its... access networks to the core network should be able to select one copy of the data to send to the destination Data content synchronization: Pieces of data arriving from multiple base stations to a mobile at the same time should be copies of the same data in order for the mobile’s radio system to combine these copies into a correct single copy In today’s circuit-switched CDMA networks such as IS- 95 [5] ,... the user’s home network becomes the Roaming Broker 4.2 MOBILITY MANAGEMENT IN IP NETWORKS This section discusses the fundamental issues of mobility management in wireless IP networks and examines existing IP mobility management protocols The current standard protocol defined by the IETF for mobility management in IPv4 networks is commonly referred to as Mobile IPv4 or MIPv4 (Section 4.2.2) MIPv4 enables... location areas is called the movement threshold Most existing wireless networks (e.g., GSM, GPRS, 3GPP, 3GPP2) use a special case of a movement-based location update strategy in which the movement 166 MOBILITY MANAGEMENT threshold is one; i.e., a mobile updates its location every time it moves into a new location area Distance-based update [11], [54 ], [13], [33]: A mobile performs a location update whenever... one type of radio system to another (e.g., from WLAN to a cellular system) A future wireless IP network should meet several basic mobility management requirements: Support all forms of mobility: A future wireless IP network should support all forms of mobility Support mobility for all types of applications: A future wireless IP network should be able to support the mobility for both real-time and non-real-time... areas can be static or dynamic A static paging area does not change unless reconfigured by the network operator manually or via a network management system Existing second-generation wireless networks and the third-generation wireless standards (e.g., 3GPP and 3GPP2) typically use fixed paging areas Dynamic paging areas have been proposed in the literature to reduce paging overhead The idea is to dynamically... become an IETF standard 4.2 MOBILITY MANAGEMENT IN IP NETWORKS 177 Fig 4 .5 Roaming Broker Existing IP-layer mobility management protocols alone typically cannot support user mobility Application-layer mobility management protocols have been proposed to support both terminal and user mobility The most widely studied application-layer mobility protocol is SIP-based mobility management (Section 4.2.6) As discussed... process in which a mobile terminal changes its network attachment point For example, a mobile may be handed off from one wireless base station (or access point) to another, or from one router or switch to another Roaming is the ability for a user to move into and use different operators’ networks 4.1 BASIC ISSUES IN MOBILITY MANAGEMENT 163 Network access control: Network access control is a process used . terminal to move to a new location, IP-Based Next-Generation Wireless Networks: Systems, Architectures, and Protocols, By Jyh-Cheng Chen and Tao Zhang. ISBN 0-471-2 352 6-1 # 2004 John Wiley & Sons,. Then, we will focus on mobility management methodologies for IP networks, 3GPP packet networks, 3GPP2 packet networks, and MWIF networks. 4.1 BASIC ISSUES IN MOBILITY MANAGEMENT Mobility can take. and time- based strategies are the most commonly used strategies in existing wireless networks and in 3G wireless networks (e.g., 3GPP and 3GPP2). Selection of location update strategies should