All-IP System MMD Roaming Technical Report

Transcription

1 GPP X.R00-0 Version.0 Version Date: August 00 All-IP System MMD Roaming Technical Report COPYRIGHT NOTICE GPP and its Organizational Partners claim copyright in this document and individual Organizational Partners may copyright and issue documents or standards publications in individual Organizational Partner's name based on this document. Requests for reproduction of this document should be directed to the GPP Secretariat at Requests to reproduce individual Organizational Partner's documents should be directed to that Organizational Partner. See for more information.

2 X.R00-0 v.0 0 CONTENTS List of Figures...ii Foreword...iii Revision History...iv Introduction.... Scope... References.... Normative References.... Informative References... Definitions, Symbols and Abbreviations.... Definitions..... Symbols and Abbreviations... Problem Statement... Roaming Scenarios.... Scenario, Signaling and bearer routed via Mobile IP in Home Network.... Scenario, Signaling and bearer routed via Mobile IP in Visited Network.... Scenario, Visited P-CSCF, no Mobile IP.... Scenario, Home P-CSCF, no Mobile IP.... Scenario, Home P-CSCF, two IP addresses... Recommendations...0. Dual IP Address Approach...0 i Contents

3 X.R00-0 v.0 LIST OF FIGURES Figure Entities in the roaming architecture... Figure Scenario... Figure Scenario... Figure Scenario... Figure Scenario... Figure Scenario... Figure Dual IP Address Model BList of Figures ii

4 X.R00-0 v.0 0 FOREWORD (This foreword is not part of this Standard.) "Shall" and "shall not" identify requirements to be followed strictly to conform to this document and from which no deviation is permitted. "Should" and "should not" indicate that one of several possibilities is recommended as particularly suitable, without mentioning or excluding others, that a certain course of action is preferred but not necessarily required, or that (in the negative form) a certain possibility or course of action is discouraged but not prohibited. "May" and "need not" indicate a course of action permissible within the limits of the document. "Can" and "cannot" are used for statements of possibility and capability, whether material, physical or causal. iii BForeword

5 X.R00-0 v.0 REVISION HISTORY Revision Remarks Date 0 v.0 Initial publication August 00 0 BRevision History iv

6 X.R00-0 v.0 Introduction 0. Scope This technical report provides guidelines for Multi-Media Domain (MMD) roaming between GPP systems, including IP Multimedia Subsystem (IMS) and related Packet Data Subsystem (PDS) aspects. It also covers aspects of inter-access technology roaming, for example roaming between Wireless Local Area Network (WLAN) and High-Rate Packet Data (HRPD). MMD Roaming is defined as the ability for a user to obtain IMS services through the home network even when connected to the visited network. The terms home and visited do not necessarily imply geographical distance, only a different relationship with the user, where the home network owns the user s subscription and the visited network provides packet data access and can be different from the home network. The visited network can use the same access technology as the home network or a different access technology, and can be owned by the home-network operator or a different operator. Users can roam to other networks using access technologies such as WCDMA, HRPD, and WLAN. Ideally, IMS is agnostic to packet-based, access network technologies, so services are expected to work while roaming without special considerations. However, there are some access network specific procedures, and, when roaming, it is important to look closely at issues like QoS, policy control, and charging. This document does not address the roaming architecture for emergency services. This document contains example scenarios for mobiles which roam into a visited network that is different from their home network. It offers recommendations on how these roaming scenarios may be supported.. BScope BIntroduction

7 X.R00-0 v.0 References. Normative References None.. Informative References [] GPP X.S00-A v.0 Multi-Media Domain series, November 00. [] GPP X.S00-00-D v.0, cdma000 Wireless IP Network Standard, Simple IP and Mobile IP Access Services, March 00. [] GPP X.S00-0 v.0, cdma000 Wireless Local Area Network Interworking, April 00. [] GPP S.R0 v.0, Network Evolution for GPP Networks [] GPP A.S000-B v.0: Interoperability Specification (IOS) for High Rate Packet Data (HRPD) Radio Access Network Interfaces with Session Control in the Access Network. [] GPP A.S000-B v.0: Interoperability Specification (IOS) for High Rate Packet Data (HRPD) Radio Access Network Interfaces with Session Control in the Packet Control Function. 0 BReferences. BNormative References

8 X.R00-0 v.0 Definitions, Symbols and Abbreviations 0. Definitions This section contains definitions, symbols and abbreviations that are used throughout the document. None.. BDefinitions BDefinitions, Symbols and Abbreviations

9 X.R00-0 v.0.. Symbols and Abbreviations FA Foreign Agent HA Home Agent HoA Home Address H-PCRF Home Policy and Charging Rules Function HRPD High-Rate Packet Data IMS IP Multimedia Subsystem IP Internet Protocol MIP Mobile IP MIP Mobile IPv MIPv Mobile IPv MMD Multi-Media Domain P-CSCF Proxy Call Session Control Function PDIF Packet Data Interworking Function PDS Packet Data Subsystem PDSN Packet Data Serving Node QoS Quality of Service RAN Radio Access Network RO Route Optimization RTP Realtime Transport Protocol SBBC Service Based Bearer Control S-CSCF Serving Call Session Control Function SIP Session Initiation Protocol UE User Equipment V-PCRF Visited Policy and Charging Rules Function WCDMA Wideband Code Division Multiple Access WLAN Wireless Local Area Network 0 BDefinitions, Symbols and Abbreviations. BDefinitions

10 X.R00-0 v.0 0 Problem Statement The MMD system [] provides home operator control of IMS services. This is done by anchoring signaling for SIP service control at the S-CSCF in the home system. However, routing all bearer traffic via the home system could cause unnecessary delay for real-time flows. According to operators requirements, a method is to be defined to allow for the home network operator to control whether packets to/from the UE are routed locally through the visited network or via the home network. If SBBC is supported, the system will support policy and charging control in both the home and visited networks while users are roaming. The solution needs to support the requirements listed in [].. BDefinitions BProblem Statement

11 X.R00-0 v.0 Roaming Scenarios P-CSCF V-PCRF Local HA PDSN/PDIF UE The following architecture diagram shows the entities used to describe roaming scenarios. Depending on the scenario, some entities will not be used (e.g., a P-CSCF is needed in the visited or home network but not both.) Visited Network RAN (HRPD, WLAN...) UE Figure Home Network Entities in the roaming architecture S-CSCF P-CSCF H-PCRF HA PDIF The scenarios consider usage of Simple or Mobile IP [], IPv or IPv, P-CSCF in home or visited networks and whether all IP flows (e.g., signaling and bearer) are required to tunnel via the home network. 0 BRoaming Scenarios. BDefinitions

12 X.R00-0 v.0 0 In the following sections, it is assumed that UE and UE are in the same visited network, belong to the same home operator and are served by the same S-CSCF. The conclusions and recommendation don t change if the UEs belong to different operators or served by different S-CSCFs. If SBBC is supported in the visited and home networks, a V-PCRF is present in the visited network and H-PCRF is present in the home network and Ty terminates in the PDSN and PDIF.. BDefinitions BRoaming Scenarios

13 X.R00-0 v.0. Scenario, Signaling and bearer routed via Mobile IP in Home Network In this scenario (see Figure ), the UE establishes a MIP tunnel to an HA in the home network. All packets for SIP signaling and RTP flows are routed via the HA. The UE can access IMS from HRPD RAN or WLAN. MIP is used for inter-technology mobility management between HRPD and WLAN []. For intra-hrpd mobility management, it s desirable to use a mechanism to anchor PDSN for the duration of a SIP call. For example, PDSN can be anchored via fast handoff or meshing topology between PDSNs and HRPD RANs (see [] and []). Figure Scenario 0 BRoaming Scenarios. BDefinitions

14 X.R00-0 v.0 0 Advantages: IMS support in visited network not required. Stable SIP contact address due to MIP binding at HA Disadvantages: Does not meet performance requirement to allow low media latency for MIPv and MIP without RO. FA support in visited network required for MIPv (note that CDMA Development Group has endorsed this requirement for inbound roaming.). Scenario, Signaling and bearer routed via Mobile IP in Visited Network In this scenario (see Figure ), the UE establishes a MIP tunnel to an HA in the visited network. All packets for SIP signaling and RTP flows are routed via the HA. The UE can access IMS from HRPD RAN or WLAN. MIP is used for inter-technology mobility management between HRPD and WLAN. For intra-hrpd mobility management, it s desirable to use a mechanism to anchor PDSN for the duration of a SIP call. For example, PDSN can be anchored via fast handoff or meshing topology between PDSNs and HRPD RANs (see [] and []).. BScenario, Signaling and bearer routed via Mobile IP in Visited Network BRoaming Scenarios

15 X.R00-0 v.0 Advantages: Figure Scenario IMS support in visited network not required. Stable SIP contact address due to MIP binding at HA Enables low media latency Disadvantages: Dynamic HA assignment support in visited network required If the UE moves to other visited networks, operator policy can prevent the UE from accessing this HA. 0 BRoaming Scenarios. BScenario, Signaling and bearer routed via Mobile IP in Visited Network

16 X.R00-0 v.0. Scenario, Visited P-CSCF, no Mobile IP 0 In this scenario (see Figure ), the UE obtains an IP address from the visited network and discovers a P-CSCF in the visited network. RTP flows can be routed locally. The UE can access IMS from HRPD RAN or WLAN. Multiple registration and VCC-like procedures are required for inter-technology mobility management between HRPD and WLAN. For intra- HRPD mobility management, it s required to use a mechanism to anchor PDSN for the duration of a SIP call. For example, PDSN can be anchored via fast handoff or meshing topology between PDSNs and HRPD RANs (see [] and []). Figure Scenario. BScenario, Visited P-CSCF, no Mobile IP BRoaming Scenarios

17 X.R00-0 v.0 Advantages: Enables low media latency. Disadvantages: IMS support in visited network required. If IP address changes, SIP sessions are terminated and UE needs to re-register with IMS network.. Scenario, Home P-CSCF, no Mobile IP In this scenario (see Figure ), the UE obtains an IP address from the visited network and uses a P-CSCF in the home network. The RTP flows can be routed locally, and the UE exchanges the signaling traffic with the P-CSCF located in the home network. The UE can access IMS from HRPD RAN or WLAN. Whenever the UE acquires new IP address [e.g. new PDSN is assigned], the existing SIP sessions are not terminated. Upon acquiring the new IP address, the UE registers and subsequently transfers all existing SIP sessions to new IP address. 0 BRoaming Scenarios. BScenario, Home P-CSCF, no Mobile IP

18 X.R00-0 v.0 0 Figure Scenario Note: The session transfer mechanisms mentioned above cannot be done based on existing MMD specifications (e.g., MMD Rev-0, MMD Rev-A, MMD Rev-B). However, new functionalities to support such transfer mechanisms may be developed in the future. The session transfer mechanism is used only for inter-technology mobility management between HRPD and WLAN. For HRPD mobility management, it s required to use a mechanism to anchor the PDSN [e.g., Simple IP] for the duration of the SIP call. For example, PDSN can be anchored via fast handoff or meshing topology between PDSNs and HRPD RANs (see [] and []). Advantages: Enables low media latency. IMS support in visited network not required.. BScenario, Home P-CSCF, no Mobile IP BRoaming Scenarios

19 X.R00-0 v.0 No loss of SIP sessions when UE acquires new IP address [e.g. changes the PDSN]. No Mobile IP is required. If limited mobility is required, the Simple IP suffices. Disadvantages: UE needs to re-register with the IMS network if the IP address changes. The SIP session transfer needs to be performed for each SIP session individually. The UE needs to support the simultaneous registration of two IP addresses. This functionality is not supported by existing MMD specifications.. Scenario, Home P-CSCF, two IP addresses In this scenario (see Figure ), the UE uses a Simple IP address obtained from the visited network for media and uses a Mobile IP Home Address (HoA) obtained from the home network for IMS signaling. The UE uses a P-CSCF in the home network. The RTP flows can be routed locally via Simple IP, if the home operator so desires. The UE can access IMS from the HRPD RAN or WLAN. For the media, SIP re-invite or UPDATE are used for intertechnology mobility management between HRPD and WLAN, while the Mobile IP insures that the mobility has no impact on the IMS signaling. For HRPD mobility management, it is required to use a mechanism to anchor the IP address obtained from the visited network for the duration of a SIP call. For example, when Simple IP is used, the PDSN can be anchored via fast handoff or meshing topology between PDSNs and HRPD RANs (see [] and []). A second HA in the visited network may also provide the anchoring function. 0 BRoaming Scenarios. BScenario, Home P-CSCF, two IP addresses

20 X.R00-0 v.0 0 Advantages: Enables low media latency. Figure Scenario IMS support in visited network not required. Stable SIP contact address due to MIP binding at HA. Disadvantages: FA support in the visited network is required for MIPv. (Note that CDMA Development Group has endorsed this requirement for inbound roaming.) If second HA is used, Dynamic HA assignment support in visited network is required.. BScenario, Home P-CSCF, two IP addresses BRoaming Scenarios

21 X.R00-0 v.0 Recommendations Note that the scenarios in section are non exhaustive, and the specific technology that the visited system may use for local IP mobility is not considered in this report. Based on the comparison in Section, the two IP address approach is recommended in this section.. Dual IP Address Approach The basic idea of dual IP address approach is similar to scenario above and is to provide a UE with two IP addresses, one provided by the visited network and one provided by the home network. These addresses can be used for different purposes, according to operator policies. One address would be a Mobile IP address (HoA) provided by the HA in the home network that would be relatively stable (and would survive as the UE moves within and between access technologies.) Another address would be a Simple IP address provided by the PDSN or PDIF in the visited system and is useful for services such as local emergency service and services (e.g., voice) that have low latency requirements. The UE will decide which address to use for each application. This decision in the UE is determined by a subscriber-specific policy in the UE. Figure Dual IP Address Model This model allows for highly stable anchoring for signaling via Mobile IP, while providing low latency transport for media via Simple IP. In the event that the visited address changes during a voice call, the mobile could use SIP signaling to update media address to the correspondent node. The use of such techniques yields better handoff performance if the UE has dual tuners as in the case of inter-technology handoff between HRPD and WLAN. For intra-technology handoff within HRPD, it s desirable to maintain the same visited address via techniques such as inter-pdsn fast handoff, or meshing topology between PDSNs and HRPD RANs (see [] and []). 0 BRecommendations 0. BDual IP Address Approach