WiMAX End-to-End Network Systems Architecture (Stage : Architecture Tenets, Reference Model and Reference Points) [GPP WiMAX Interworking] Authorized Distribution: Public Access subject to stated terms. WiMAX Forum Members Standards Development Organizations & SDO Members General Public X X X This is an unapproved This is an unapproved draft, which draft, is subject to to change. without notice. April, 00 DRAFT APRIL, 00 DRAFT Special document status information appears on Page i. This document is subject to the notices, restrictions, limitations and WiMAX disclaimers Forum as provided Proprietary at Pages i iii. For Reference Purposes Only 00 WiMAX Forum. All Rights Reserved. WiMAX Forum Proprietary For Reference Purposes Only 00 WiMAX Forum. All Rights Reserved.
NWG Stage - GPP - WiMAX Interworking - Release 0 0 0 0 0 Special Note Regarding Document Status. This is a Verification and Validation Readiness Ballot Document of the WiMAX Forum Network Working Group, which the Working Group has prepared for its own internal use in the Specification development process. As with any early-stage work in progress, this document can and will contain errors and omissions of various kinds, which the Working Group is in the process of addressing and resolving through the verification and validation process. This document is subject to change without notice and will likely change as a result of the ongoing verification and validation process. AS A NONFINAL, UNAPPROVED DRAFT DOCUMENT, THIS DOCUMENT CANNOT BE REGARDED AS A STATEMENT OF THE WORKING GROUP THAT IS PREPARING IT OR OF THE WiMAX FORUM REGARDING THE SUBJECT MATTER HEREIN. Copyright Notice, Use Restrictions, Disclaimer, and Limitation of Liability. The WiMAX Forum TM owns the copyright in this document and reserves all rights therein. Use of this document and any related materials is limited as follows: A. General Public Access: A member of the general public who is interested in this document may download it solely for that person s personal use on the condition that the person downloading it does not modify, distribute, sell, or repackage the document in any form or create derivative works using the document without the prior written consent of the WiMAX Forum. B. WiMAX Forum members. In addition to the general public access rights, WiMAX Forum members may use this document in both editable and noneditable form in connection with WiMAX Forum activities, as directed by the Working Group that produced it. Member rights include the right to modify, duplicate and distribute to other members in connection with authorized WiMAX Forum activities. C. Participants in the standards development activities of other organizations. In addition to the general public access rights, participants in the standards development activities of other organizations may specifically use this document for reference purposes, namely (i) to review and evaluate the WiMAX Forum s use and implementation of third-party standards in its technical documents, and (ii) to review, evaluate and, in their sole discretion, adapt their standards activities in a manner that encourages, promotes and/or implements enhanced compatibility and/or interoperability between their respective standards and the standards that the WiMAX Forum is promoting. As part of these activities, a user of this document may duplicate and distribute copies of the document. Any duplication in whole or in part will include the copyright notice on the first page of this document and all notices and restrictions contained in this Section of the document ( Copyright Notice, Use Restrictions, Disclaimers and Limitation of Liability ). Except for the foregoing or as expressly authorized by the WiMAX Forum in writing, any other use of this document and all other duplication and distribution of this document are prohibited. The WiMAX Forum regards the unauthorized use, duplication or distribution of this document by a member as a material breach of the member s obligations under the organization s rules and regulations, which may result in the suspension or termination of its WiMAX Forum membership. Unauthorized use, duplication, or distribution by nonmembers is an infringement of the WiMAX Forum s copyright. Use of this document is subject to the additional disclaimers and limitations described below. By using this document, the user agrees to the following terms and conditions: THIS DOCUMENT IS PROVIDED AS IS AND WITHOUT WARRANTY OF ANY KIND. TO THE GREATEST EXTENT PERMITTED BY LAW, THE WiMAX FORUM DISCLAIMS ALL EXPRESS, IMPLIED AND STATUTORY WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF TITLE, NONINFRINGEMENT, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE WiMAX FORUM DOES NOT WARRANT THAT THIS DOCUMENT IS COMPLETE OR WITHOUT ERROR AND DISCLAIMS ANY WARRANTIES TO THE CONTRARY. The user acknowledges that any products or services provided using technology described in or implemented in connection with this document may be subject to various regulatory controls under the laws and regulations of various governments worldwide. The user acknowledges that it is solely responsible for the compliance of its products with any such laws and regulations and for obtaining any and all required authorizations, permits, or licenses for its products as a result of such regulations within the applicable jurisdiction. Page - i
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NWG Stage - GPP - WiMAX Interworking - Release 0 TABLE OF CONTENTS. INTERNETWORKING WITH GPP.... SCOPE.... INTEGRATION OF WIMAX ACCESS NETWORK ACCORDING TO THE GPP TS. MODEL.... DETAILED ARCHITECTURE OF THE WIMAX ACCESS NETWORK.... REFERENCE POINTS LINKING THE WIMAX ACCESS NETWORK TO THE GPP SYSTEM.... ADDITIONAL CONSIDERATIONS AND LIMITATIONS REQUIRING FURTHER STUDY... TABLE OF FIGURES FIGURE - LOOSE COUPLING APPROACH TO WIMAX INTERWORKING WITH GPP CORE... FIGURE - WIMAX GPP NETWORK INTERWORKING GENERAL ARCHITECTURE... FIGURE - WIMAX-GPP INTERWORKING (NON-ROAMING CASE)... TABLES TABLE WIMAX-GPP INTERWORKING SCENARIOS (BASED ON TABLE OF TR.)... Page - iii
NWG Stage - GPP - WiMAX Interworking - Release. Internetworking with GPP Note: See.0 References in WiMAX End-to-End Network Systems Architecture [Part ] for references cited in this document.. Scope WiMAX-GPP Interworking refers to the integration of a WiMAX Access Network to an existing GPP core network. Loosely coupled Interworking, compatible with PWLAN-GPP Interworking as specified in Release, is preferred. Billing Server PDG Internet Home AAA WAG Home Agent GPP Core Network GGSN WiMAX Network Service Provider RNC SGSN Local AAA GPP Access Network Loosely-Coupled Internetworking FA WiMAX ASN GPP Card WiMAX Card WiMAX Base Stations 0 0 UE Figure - Loose Coupling Approach to WiMAX Interworking with GPP core This architecture enables a GPP operator to grant its authenticated subscribers access to GPP services (GPP PS Packet Switched domain) through a WiMAX Access Network. We introduce here the notion of WiMAX Access Network by analogy to the WLAN Access Network used in []. We will describe more precisely later in the following sections what WiMAX Access Network refers to in terms of WiMAX entities. GPP has defined in [] (and more generally in the. family which mainly includes TS., TS. and TS.) an architecture describing Interworking between GPP systems and Wireless Local Area Networks (WLAN). In order to keep consistency in Interworking between GPP systems and Wireless Access Networks, Interworking with WiMAX Networks SHALL be based on the same model. There are ongoing discussions in GPP SA group aiming at extending the scope of [] to a wider range of IP-based Access Networks, including IEEE 0. family). Page -
NWG Stage - GPP - WiMAX Interworking - Release 0 [] provides stage specifications for the first three interworking scenarios described in [] for public WLAN Interworking with GPP Networks. This informative section will map the first three scenarios of WiMAX-GPP Interworking to the first three WLAN-GPP Interworking (As it has been done in Annex A of []). The features of these scenarios are summarized in the table A- (based on a table from GPP TR. document) and described hereafter. Scenario is the simplest case and does not have any impacts on neither GPP nor WiMAX architecture. This just means a transparency for the subscriber in its relationship with his/her operator: the subscriber will be charged on the same bill for usage of both GPP and WiMAX services, and custom care will be ensured without dependency on the connecting platform. In Scenario (or WiMAX Direct IP access), a subscriber MAY use the WiMAX Access network to access e.g. the Internet, but AAA operations are handled by the GPP platform. Scenario (or WiMAX GPP IP access) allows the operator to extend GPP system Packet Switched (PS) based services to the WiMAX network. In this scenario, an authenticated GPP subscriber can access to GPP PS services through a WiMAX Access Network Interworking with its GPP PLMN (non roaming case) or with a visited GPP PLMN (roaming case). Note, that for WiMAX GPP IP access, per TS. WiMAX Direct IP access has to be performed in advance for initiating protection of the R wireless link and the final establishment of the Wu tunnel. Table WiMAX-GPP Interworking Scenarios (Based on Table of TR.) Scenarios Service and operational Capabilities: Scenario : Common Billing and Customer Care Scenario : GPP system based Access Control and Charging Scenario : Access to GPP system PS based services Common Billing X X X Common Customer Care X X X GPP System Based Access Control X X GPP System Based Access Charging X X Access to GPP System PS Based Services from WiMAX X Page -
NWG Stage - GPP - WiMAX Interworking - Release 0. Integration of WiMAX Access Network According to the GPP TS. Model Our goal is to fit WiMAX-GPP Interworking in the present GPP model of Interworking with alternate Access Networks. That implies a certain number of requirements from GPP side. From a GPP network perspective, a WLAN Interworking is considered as an untrusted network. As WiMAX is also presently considered an untrusted network, it is then necessary to ensure the same level of security to a user for WiMAX GPP IP access through this interworking network than a user accessing the GPP IP services under regular GPP operations. AAA traffic: Proper security and trust relationship need to exist between the GPP AAA server and the WiMAX Access Network to support proper transfer of security, authorization and accounting material. Data traffic: The technical solution chosen by GPP for WLAN GPP IP access security (described mainly in []) is to establish a tunnel between the user equipment and the GPP Gateway located on the border of GPP PS. Unless otherwise mentioned, all the content of the [] SHALL be applied to the WiMAX Interworking case. Figure A. (based on figure. of []) describes the interaction between an Interworking Network (e.g. WiMAX Access Network) and the rest of the [] architecture. Internet/ Intranet UE Interworking Network e.g. WLAN or WiMAX Access network GPP AAA Server Parket Data GW Internet/ GPP PS Services 0 Figure - WiMAX GPP Network Interworking General Architecture This subsection concentrates on the interfaces between the WiMAX Access Network bloc and the GPP Network bloc. The internal operations of the GPP bloc are defined in []. The detailed architecture of the WiMAX Access Network bloc will be described in the following section. All the internal operations of the WiMAX Access Network bloc SHALL be done according to what is described in the appropriate sections of the NWG document (normal WiMAX operations). This document only considers the GPP non-roaming case (access to the home GPP PLMN through the WiMAX Access Network), because the changes implied by the roaming case (when the WiMAX Access Network is connected to a visited GPP PLMN) do not affect the WiMAX Access Network bloc and are thus out of scope of this document (this is described in []) Page -
NWG Stage - GPP - WiMAX Interworking - Release. Detailed Architecture of the WiMAX Access Network WiMAX Access Network Internet Another WiMAX ASN GPP Home Network MS R R AAA Client WiMAX ASN R AAA Relay WiMAX CSN IWU Wa Wn GPP AAA Server WAG Wp PDG Packet Data Wi Network (GPP PS, Internet) 0 0 0 Wu Figure - WiMAX-GPP Interworking (Non-Roaming Case) Figure represents the WiMAX-GPP Interworking architecture and the appropriate Reference Points. What is referred to as WiMAX Access Network by analogy to WLAN Access Network is thus composed of WiMAX ASNs, connected to the GPP Network through a WiMAX CSN providing IP Connectivity. This slight difference is due to the fact that unlike the WLAN AN, which provides Internet connectivity in [], the WiMAX ASN does not provide direct Internet connectivity nor IP address management. Therefore, a WiMAX CSN is introduced to provide the required WiMAX CSN functions like local IP address (DHCP, DNS) management as well as Internet connectivity to the MS. For this, CSN anchored mobility using PMIP according to section of this specification, must be supported. It MAY also provide NAT functionality in case of private IP usage in WiMAX Access Network. The WiMAX CSN also provides a AAA proxy/server. This AAA proxy/server is in the path of the AAA signaling between the AAA client of the ASN and the GPP AAA server in the GPP home network (Wa interface to the GPP core network). It is responsible for generating appropriate PMIP keys and distributing these keys to the involved entities of the WiMAX network (i.e., HA and PMIP client). Distribution of these key happens in compliance with the mechanisms specified in section.., where the AAA proxy/server (instead of the GPP AAA that is not assumed to be WiMAX MIP-aware) interfaces with the HA in the CSN, and adds the PMIP keys to the AAA response of the GPP AAA server during user authentication, such that the PMIP client in the ASN receives these keys required for PMIP operation. The MS in this release must not use CMIP for WiMAX interworking by GPP subscribers. If the WiMAX CSN receives a CMIP registration attempt by a GPP subscriber using WiMAX direct IP access, this registration attempt will fail due to wrong CMIP keys. It is also not supported to run a combined device/user authentication (using single-eap) due to the fact that a GPP AAA server cannot be assumed to support this authentication mode. It is, however, possible to perform device authentication in addition to user authentication if device authentication terminates in the WiMAX network.. Reference Points Linking the WiMAX Access Network to the GPP System In the current [], reference point Ww connects the User Equipment to the WLAN Access Network; it mandates on this reference point the use of 0.X to address the lack of a proper Access Control in 0.. Page -
NWG Stage - GPP - WiMAX Interworking - Release 0 0 0 0 [] directly addresses this problem by the use of PKMv (which can in particular transport the two requested authentications methods of []: EAP-SIM and EAP-AKA), so we will keep in this model the Reference Point R between the WiMAX MS and the WiMAX ASN. For matter of simplicity, the ultimate goal will be to use the Ww reference point in this model as well. That will be possible when relevant adaptation will be made in [] to also address the specificities of []. Wu remains as defined in [] and refers to tunnel establishment and tear down between MS and the appropriate PDG (Packet Data Gateway), as well as user data packet transmission through this tunnel. PDG functionalities are described in details in []. Wa is dedicated to the transport of AAA messages coming from the MS between the AAA client located in the WiMAX Access Network to GPP AAA server. A AAA Proxy/Server must be located in the CSN to provision keys for mobile IP operation within the WiMAX network. In cases where the WiMAX and GPP AAA infrastructure speak different AAA protocols, a RADIUS/Diameter translation box needs to be inserted at one side of the Wa interface. Wn links the WiMAX Access network and the WAG (WLAN Access Gateway). The WAG is a gateway toward which the data coming from the WiMAX Access Network SHALL be routed. It is used to enforce the routing of packets through the appropriate PDG. WAG functionalities are described in details in [].. Additional Considerations and Limitations Requiring Further Study Network Detection and selection: once the MS has detected the available ASNs and corresponding IWU CSN in a given area by the means of methods described in section. of the NWG document, the selection of the PLMN SHALL be done accordingly to TS.. Inter/Intra ASN mobility: As far as scenarios up to scenario are concerned (no inter-system mobility considered), inter/intra ASN mobility SHALL be transparent to the GPP system part. It can be achieved by the use of MIP protocol as defined in the corresponding part of the NWG document. (HA located in the WiMAX CSN). Scenario based on the Wu Reference point consisting in the VPN tunnel might not allow the WiMAX terminal to enter the idle mode for power consumption saving due to the maintenance of the VPN connection in an active state. Further development with GPP SA is required to enable idle terminals. WiMAX provides powerful and flexible QoS handling which can't be fully utilized within the current GPP- WLAN Interworking specification. GPP SA is currently extending the specification for utilizing QoS-enabled IP-based access networks. For leveraging the MIP functionality in the WiMAX for inter-technology handovers, it would be wishful to overcome the limitation of Wu reference point. Further development with GPP SA is required. Handoff capability from GPP network to WiMAX network is usually referred as scenario (intersystem mobility) and (seamless intersystem mobility). These scenarios are out of scope of release, but they will be addressed in future releases. Some cleaning/rephrasing has to be done in the subsequent GPP specifications to fully include WiMAX Interworking in their scope. Namely, all the section dealing with ND&S, Ww Reference Point in [], [], [] and [] have to be adapted to reflect more technology neutrality. Work has to be done in close relationship with GPP to study how WiMAX specificities (including Idle Mode and QoS and future inter-technology handover as said in the points above) could be taken in account in the Interworking architecture model. CMIP operation, due to the fact that o o a GPP AAA server cannot be assumed to derive WiMAX-specific mobility keys from the EMSK, and the (visited) WiMAX network and roaming GPP subscribers cannot be assumed to have pre-shared mobility keys, Page -
NWG Stage - GPP - WiMAX Interworking - Release is not supported by this WiMAX release. For future releases the goal is to also support CMIP operation for roaming GPP subscribers. Page -