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기술보고서 TTA Technical Report TTAR-xx.xxxx 개정일: 20xx년 xx월 xx일 3GPP 이종망 연동 기술 표준 분석(기술보고서) 3GPP Standardization Status for Interoperability with other RATs(Technical Report) 기술보고서 TTAR-xx.xxxx 개정일: 201x년 xx월 xx일 3GPP 이종망 연동 기술 표준 기술 분석(기술보고서) 3GPP Standardization Status for Inter-operability with other RATs (Technical Report) 본 문서에 대한 저작권은 TTA 에 있으며, TTA 와 사전 협의 없이 이 문서의 전체 또는 일부를 상업적 목적으로 복제 또는 배포해서는 안 됩니다. Copyrightⓒ Telecommunications Technology Association YYYY. All Rights Reserved. 기술보고서 서 문 1. 기술보고서의 목적 무선 데이터 수요 증가에 따라 WLAN 기술을 이용한 데이터 분석 기술과 heterogeneous network 운용을 위한 3GPP 내 이종망 연동에 대한 표준 논의가 활발히 진행되고 있는 바, 본 기술보고서는 이에 대한 기술 및 표준 동향을 분석하여 제시한다. 본 기술보고서는 앞으로의 3GPP LTE/LTE-A 망과 WLAN 등의 이종망 간 연동의 국제 표준 및 시장 동향을 예측하고 대응하기 위한 참고 문서로 활용될 것이다. 2. 주요 내용 요약 본 기술보고서는 3GPP TSG SA, RAN 등에서 Release 6 이후 현재까지 논의되고 있는 3GPP 망과 WLAN 등의 이종망과의 연동에 관한 표준 진행 상황을 검토하고, 3GPP이종망간 심리스 핸드오버, 트래픽 스티어링 기술에 관한 표준과 표준안을 분석한다. 3. 기술보고서 적용 산업 분야 및 산업에 미치는 영향 LTE 네트워크와 WLAN 등의 네트워크들 간의 심리스 핸드오버 서비스를 제공 가능하게 함으로써 이용자들에게는 사용자 경험 환경의 품질을 높이고 네트워크 사업자에게는 무선 네트워크 자원을 효율적으로 관리 운용하여 경쟁력을 높일 수 있다. 4. 참조 표준(권고) 4.1. 국외 표준(권고) - 해당 사항 없음. 4.2. 국내 표준 - 해당 사항 없음. i TTAR-xx.xxxx 기술보고서 5. 참조 표준(권고)과의 비교 5.1. 참조 표준(권고)과의 관련성 - 해당 사항 없음. 5.2. 참조한 표준(권고)과 본 표준의 비교표 - 해당 사항 없음. 6. 지식 재산권 관련 사항 본 기술보고서의 ‘지식 재산권 확약서’ 제출 현황은 TTA 웹사이트에서 확인할 수 있다. ※ 본 기술보고서를 이용하는 자는 이용함에 있어 지식 재산권이 포함되어 있을 수 있으므로, 확인 후 이용한다. ※ 본 기술보고서와 관련하여 접수된 확약서 이외에도 지식 재산권이 존재할 수 있다. 7. 시험 인증 관련 사항 7.1. 시험 인증 대상 여부 - 해당 사항 없음. 7.2. 시험 표준 제정 현황 - 해당 사항 없음. ii TTAR-xx.xxxx 기술보고서 8. 기술보고서의 이력 정보 8.1. 기술보고서의 이력 판수 제정개정일 제1판 20014.xx.xx. 제정개정내역 제정 TTAR.xx-xx.xxxx 8.2. 주요 개정 사항 - 해당 사항 없음. iii TTAR-xx.xxxx 기술보고서 Preface 1. Purpose of Technical Report The purpose of this Technical Report provides the technologies and standardization status considering the active discussions in 3GPP for the interworking with WLAN for better resource utilization between 3GPP and WLAN access. This report is expected to be a reference for forecasting the trends of global standards and markets on the interworking between 3GPP LTE/LTE-A and WLAN. 2. Summary of Contents This Technical Report introduces the standardization status of 3GPP TSGs (SA and RAN) on the 3GPP-WLAN interworking. This report also analyzes the technologies of seamless handover and traffic steering between 3GPP and WLAN access networks based on the standards and draft documents. 3. Applicable Fields of Industry and its Effect This technical report will provide mobile subscribers with the seamless handover between the 4th generation mobile network like LTE/LTE-A and WLAN to enhance the performance experience. This will also provide mobile network operators with the efficient network resource utilization to increase the competiveness in the market. 4. Reference Standards(Recommendations) 4.1. International Standards(Recommendations) - None iv TTAR-xx.xxxx 기술보고서 4.2. Domestic Standards - None 5. Relationship to Reference Standards(Recommendations) 5.1. Relationship of Reference Standards - None 5.2. Differences between Reference Standard(Recommendation) and this Technical Report - None 6. Statement of Intellectual Property Rights IPRs related to the present document may have been declared to TTA. The information pertaining to these IPRs, if any, is available on the TTA Website. No guarantee can be given as to the existence of other IPRs not referenced on the TTA website. And, please make sure to check before applying the technical report. 7. Statement of Testing and Certification 7.1. Object of Testing and Certification - None 7.2. Standards of Testing and Certification - None v TTAR-xx.xxxx 기술보고서 8. History of Technical Report 8.1. Change History Edition Issued date The 1st edition 2014.xx.xx Outline Established TTAx.xx-xx.xxxx 8.2. Revisions - None vi TTAR-xx.xxxx 기술보고서 목 차 1. 개 요 ........................................................................................................... 1 2. 기술보고서의 구성 및 범위 ............................................................................. 1 3. 참조 표준(권고) ............................................................................................. 1 4. 용어 정의 및 약어 ......................................................................................... 2 5. 3GPP 이종망 연동 표준 기술 .......................................................................... 3 5.1. Release 6 ............................................................................................. 3 5.2. Release 8 ............................................................................................. 5 5.3. Release 10 ........................................................................................... 7 5.4. Release 11 ......................................................................................... 10 5.5. Release 12 ......................................................................................... 11 5.6. Release 13 ......................................................................................... 13 6. 결론 .......................................................................................................... 14 부록 I. 참고 문헌 ............................................................................................ 16 vii TTAR-xx.xxxx 기술보고서 Contents 1. Introduction .................................................................................................. 1 2. Constitution and Scope .................................................................................. 1 3. Reference Standards .................................................................................... 1 4. Terms and Definitions, Abbreviations ................................................................ 2 5. 3GPP Standardization Status for Inter-operability with other RATs ........................ 3 5.1. Release 6 ............................................................................................... 3 5.2. Release 8 ............................................................................................... 5 5.3. Release 10 ............................................................................................. 7 5.4. Release 11 ........................................................................................... 10 5.5. Release 12 ........................................................................................... 11 5.6. Release 13 ........................................................................................... 13 6. Conclusion ................................................................................................. 14 Appendix I. References .................................................................................... 16 viii TTAR-xx.xxxx 기술보고서 3GPP 이종망 연동 기술 표준 분석(기술보고서) (3GPP Standardization Status for Inter-operability with other RATs(Technical Report)) 1. Introduction Since the amount of traffic carried over wireless network has grown dramatically in recent years, WLAN can be an important tool for wireless carriers to meet the capacity demands of their mobile data users. So, for most operators with the dedicated carriers, WLAN is considered as an integral part of their mobile-broadband strategy. 3GPP defines I-WLAN(Interworking WLAN) functionality which provides the utilization of resources and access to services within the 3GPP system. The 3GPP-WLAN interworking is intended to extend 3GPP services and functionality to the WLAN access environment to make the WLAN effective complementary radio access technology to the 3GPP system. Starting with TR 22.934 of TSG-SA WG1, 3GPP defines the architecture and related functionalities to be able to provide 3GPP services through WLAN access. In Release 8, seamless handover and service continuity between 3GPP access and WLAN were defined. After Release 10, more evolved technologies to support WLAN in 3GPP network have been introduced. This Technical Report has the purpose of providing the technologies and standardization status considering the active discussions in 3GPP and WLAN interworking. This Technical Report is expected to a reference to develop global standards and lead the markets on the interworking between 3GPP LTE/LTE-A and WLAN. 2. Constitution and Scope This Technical Report introduces the standardization status from 3GPP Release 6 to Release 13 on the 3GPP-WLAN interworking. This report includes the technologies of seamless handover and traffic steering between 3GPP and WLAN access based on the standards and draft documents. 1 TTAR-xx.xxxx 기술보고서 3. Reference Standards - None 4. Terms and Definitions, Abbreviations 4.1. Terms and Definitions 4.1.1. Evolved Packet System An evolution of the 3G UMTS characterized by higher-data-rate, lower-latency, packet-optimized system that supports multiple RATs, comprising the Evolved Packet Core together with the evolved radio access network(E-UTRA and EUTRAN) 4.1.2. Interworking WLAN(I-WLAN) WLAN that interworks with a 3GPP system 4.1.3. 3GPP-WLAN Interworking Interworking between the 3GPP system and the WLAN family of standards 4.2 Abbreviations ANDSF Access Network Discovery and Selection Function ANQP Access Network Query Protocol APN Access Point Name CS Circuit Switched DM Device Management DSMIPv6 Dual-Stack Mobile IPv6 2 TTAR-xx.xxxx 기술보고서 EAP Extensible Authentication Protocol EPS Evolved Packet System FMC Fixed-Mobile Convergence GAS Generic Advertisement Service GPRS General Packet Radio Service GSM Global System for Mobile communications GTP GPRS Tunneling Protocol HA Home Agent HPLMN Home PLMN IARP Inter-APN Routing Policy IFOM IP Flow Mobility IP Internet Protocol IP-CAN IP Connectivity Access Network ISMP Inter-System Mobility Policy ISRP Inter-System Routing Policy I-WLAN Interworking WLAN MAPCON Multi Access PDN Connectivity MAPIM Multi Access PDN connectivity and IP flow Mobility MO Management Object NSWO Non-Seamless WLAN Offload OMA Open Mobile Alliance PCRF Policy and Charging Rules Function PDN Packet Data Network 3 TTAR-xx.xxxx 기술보고서 PLMN Public Land Mobile Network PMIP Proxy Mobile IPv6 PS Packet Switched PSPL Preferred Service Provider List RAT Radio Access Technology SaMOG S2a Mobility based on GTP SMOG S2b Mobility based on GTP TFT Traffic Flow Template TSG-RAN Technical Specification Group – Radio Access Network TSG-SA Technical Specification Group – Service & Systems Aspects UMTS Universal Mobile Telecommunications System UTRAN Universal Terrestrial Radio Access Network VoIP Voice over IP VPLMN Visited PLMN WFA Wi-Fi Alliance WLAN Wireless Local Area Network WLANSP WLAN Selection Policy WORM Optimized Offloading to WLAN in 3GPP-RAT Mobility WPA2 Wi-Fi Protected Access v2 4 TTAR-xx.xxxx 기술보고서 5. 3GPP Standardization Status for Inter-operability with other RATs 5.1. Release 6 5.1.1. WLAN-UMTS Interworking The feasibility document TR 22.934 includes a number of different scenarios of 3GPP-WLAN interworking ranging from common billing to the provision of services seamlessly between the WLAN and the 3GPP system, referred as Scenarios 1 to 6 [1]. Scenario 1: Common Billing, Common Customer Care Scenario 2: System based Access Control, 3GPP System based Access Charging Scenario 3: Access to 3GPP System PS based Services from WLAN Scenario 4: Service Continuity Scenario 5: Seamless Service Continuity Scenario 6: Access to 3GPP System CS based Services with seamless mobility The stage 1 in TS 22.234 takes the conclusions of the feasibility study and defines the high level requirements for I-WLAN. The global architecture provided in TS 22.234 is shown as below: 3GPP Home Network Ww Wn D' HLR r' /G Wo Wm WAG Offline Charging System Wf OCS Wz 3GPP AAA Server Wg WLAN Access Network Wx Dw Wa WLAN UE HSS SLF Wy Intranet / Internet Wp PDG Wi WLAN 3GPP IP Access Wu (Figure 5-1) Non-roaming reference model [2] 5 TTAR-xx.xxxx 기술보고서 As shown in the figure, Release 6 addresses different possibilities of interconnection with the internet. Scenario 1 refers to a pure commercial agreement between a "WLAN operator" and a UMTS operator, so that the user pays one single bill and does not need to subscribe to two different contracts. Scenario 2 refers to the case where the internet is accessed directly from the WLAN, i.e. the WLAN is seen as a parallel system to the 3GPP. Scenario 3 refers to the case where the actual bearer connection is supported by the UMTS Core Network and the WLAN is used instead of the UTRAN. Stage 3 protocol description defines several reference points for the WLAN-3GPP interworking: Dw, Wa, Wd, Wx, Wm, Wg, Pr. 6 TTAR-xx.xxxx 기술보고서 5.2. Release 8 5.2.1. I-WLAN Network Selection Principle The growth of public WLANs provides an opportunity for appropriately-equipped UEs to access HPLMNs and VPLMNs via the WLANs. The WLANs that provide this functionality are referred to as I-WLANs. TSG-SA WG1 aligned the requirements for the selection of I-WLAN access in TS 22.234 to the ones applicable to PLMN network selection in TS 22.011. Automatic PLMN selection procedure by WLAN UE Manual PLMN Selection Mode Procedure by WLAN UE Operator management of network preferences for I-WLAN (Figure 5-2) Interworking Model 5.2.2. Mobility between 3GPP-WLAN Interworking and 3GPP Systems TS 23.234 provides the possibility to offer access to IP services via WLAN by interworking with Release 6 3GPP systems [3]. As defined in Release 6 TR 22.934, service continuity(scenario 4) and seamless services(scenario 5) at a change of the access network(between I-WLAN and GPRS) are desirable enhancements to improve the user experience. The work was based on architectural/functional/procedural 7 TTAR-xx.xxxx 기술보고서 definitions described in TS 23.234(3GPP system to WLAN interworking; System description) and TS 23.060(GPRS; Service description; Stage 2). New TSG-SA WG2 TS 23.327 specifies the stage 2 system descriptions for providing mobility between 3GPP Wireless Local Area Network Interworking(I-WLAN) and 3GPP Systems [4]. It defines a technical solution based on the working principles of DSMIPv6 with necessary enhancement of the I-WLAN architecture for supporting mobility and roaming between 3GPP WLAN Interworking system and 3GPP Systems so that ongoing 3GPP PS based services can be maintained with minimal impact on the end user's perceived quality on the services at a change of the access network between IWLAN and 3GPP Access Systems. TS 23.327 includes both non roaming and roaming scenarios and covers all aspects, including mobility between 3GPP Systems and I-WLAN with access authentication and charging. 5.2.3. Service continuity between mobile and WLAN networks For Fixed-Mobile Convergence(FMC), some scenarios require seamless roaming between GSM/GPRS/3G mobile and WLAN networks. Both networks may independently be authenticated. To maintain the quality of the customer experience and due to the difference of networks, handovers to support service continuity may require that the handset is authenticated to both networks simultaneously, for relatively short periods of time. One use case is where the user, on the way to office, is having a call on a 3GPP access network using the mobile phone. Roaming onto the office WLAN(and vice versa), while still being on the line and the call is transferred without the user noticing any interruption to the network served by the WLAN. The study proposes requirements while roaming between a GSM/GPRS/3G mobile network and a WLAN network for: seamless roaming and service continuity; maintaining service quality and service continuity; charging; security, in particular when networks may be independently authenticated. TR 22.937 developed use cases and requirements for service continuity between a 3GPP network and another network [5]. 8 TTAR-xx.xxxx 기술보고서 5.2.4. Access Network Discovery and Selection Function(ANDSF) 3GPP IP Access or Trusted/Untrusted Non-3GPP IP Access UE S14 H-ANDSF (Figure 5-3) Non-Roaming Architecture for Access Network Discovery Support Functions ANDSF is the data management and control functionality to provide network discovery and selection assistance data per operators’ policy. The ANDSF responds to UE requests for network discovery information(pull mode operation) and may initiate data transfer to the UE(push mode operation), based on network triggers or as a result of previous communication with the UE. The Management Object(MO) consists of relevant parameters for intersystem mobility policy and access network discovery information that can be managed by the ANDSF [6]. The MO is compatible with the OMA Device Management(DM) protocol specification. The ANDSF MO is used to manage Inter-System Mobility Policy(ISMP), Inter-System Routing Policy(ISRP), Inter-APN Routing Policy(IARP), RuleSelectionInformation and WLAN Selection Policy(WLANSP) as well as access network discovery information stored in a UE supporting provisioning of such information from an ANDSF. In addition, the ANDSF MO is also used to manage the HomeOperatorPreference Policy stored in a UE supporting provisioning of Preferred Service Provider List(PSPL) and S2a Connectivity Preference information from an ANDSF. Access network discovery information: information to help the UE to discover networks in its surrounding area(e.g. network type, radio frequency, channel) Inter-System Mobility Policy(ISMP): if the UE can route IP traffic over a single radio network, the ISMP indicates which is the preferred access network(e.g. 3GPP, Wi-Fi, etc) Inter-System Routing Policy(ISRP): it contains indication on traffic distribution for UEs that are configured for IFOM, MAPCON or non-seamless WLAN offload. UE location information 9 TTAR-xx.xxxx 기술보고서 5.3. Release 10 5.3.1. IP Flow Mobility and seamless WLAN offload(IFOM) It is triggered by TR 23.861(Study on Multi Access PDN connectivity and IP flow mobility – MAPIM) [7]. When the subscriber happens to be under WLAN coverage, it is beneficial for the operator to offload some traffic(e.g. best effort) to the WLAN access. At the same time it may be beneficial to still keep some traffic(e.g. VoIP flow) in the cellular access. With this IP flow mobility solution the operator can lower it data access costs while the subscriber just experiences maximized bandwidth without any service disruption or interruption. It is therefore of interest to 3GPP community to specify a solution for operators for a seamless WLAN offload via IP flow mobility. Based on this solution, operators can use WLAN as a seamless extension of their cellular access and thus increase the overall system capacity while minimizing the access cost. Service requirements for IP Flow Mobility are partially documented in TS 22.278 [8]. In stage 2, this work item specifies a mechanism for a UE to simultaneously connect to a 3GPP access and WLAN and transmit/receive traffic belonging to different IP flows through different accesses. The mechanism enables both seamless and non-seamless IP flow mobility between a 3GPP access and WLAN. Seamless offload indicates the capability to seamlessly move one or more selected IP flows from a 3GPP network to WLAN(and vice-versa) while providing IP session continuity. Seamless offload is based on DSMIPv6. Non-seamless offload indicates the possibility to exchange the traffic of one or more selected IP flows using WLAN IP address(referred also as Direct IP Access in I-WLAN) without providing any IP session continuity. In stage 3, the work item enhances the specification to define the followings: Required procedures in UE to initiate and manage IP flows simultaneously connected to a 3GPP access and WLAN access; Extensions to S2c and H1 interfaces enabling the UE to indicate to the HA how IP flows should be distributed between a 3GPP access and WLAN access. Extensions to Gx, Rx and S9 interfaces to enable PCRF to cope with the management of multiple simultaneous connections for a single IP CAN session. Extensions to ANDSF Management Object(ANDSF MO) required to allow the operator to influence(through downloaded policies) how and what and which IP 10 TTAR-xx.xxxx 기술보고서 flows are routed between 3GPP access and WLAN access. This includes the possibility to indicate which IP flows and PDN connections(e.g. per APN) are required to be seamlessly offloaded and under what conditions and situations driven by the downloaded policies, and which are required to be nonseamlessly offloaded. Required UE actions and procedures based on policies provided by ANDSF, both in the case of non-roaming and in the case of roaming. The UE may receive policies and indications from multiple ANDSFs: a method to resolve possible conflicts and order or precedence of policies is expected to be defined. UE or HA behavior in case of abnormal or exceptional conditions are encountered when performing IP flow mobility, if abnormal or exceptional conditions are identified. (Figure 5-4) and(Figure 5-5) show the baseline architecture reference model for multi access PDN connectivity and IP flow mobility when EPS is deployed in the nonroaming case. HSS SWx S6a PCRF Rx Gxc Gx Operator's IP Services (e.g. IMS, PSS, etc.) SGi 3GPP Access Serving Gateway S5 PDN Gateway S6b Gxb SWm 3GPP AAA Server ePDG HPLMN SWn Non-3GPP Networks Gxa Untrusted Non-3GPP IP Access Trusted Non-3GPP IP Access S2c S2c UE SWa STa S2c (Figure 5-4) Non-Roaming Architecture within EPS using S5, S2c 11 TTAR-xx.xxxx 기술보고서 HSS SWx S6a PCRF Gxc Rx Gx SGi 3GPP Access Serving Gateway PDN Gateway Operator's IP Services (e.g. IMS, PSS, etc.) S5 S6b S2b Gxb SWm 3GPP AAA Server ePDG S2a SWn HPLMN Non-3GPP Networks Trusted WLAN Access Network SWw SWu Untrusted WLAN Access Network SWa STa UE UE (Figure 5-5) Non-Roaming Architecture within EPS using S5, S2a, S2b 5.3.2. S2b Mobility based on GTP(SMOG) Network-based mobility between E-UTRAN and untrusted non-3GPP accesses is provided by the S2b interface defined by TS 23.402 [9]. This interface is based on PMIPv6. With real EPS deployments approaching the time to be going live, it is now recognized it will be beneficial to also allow a GTP option for S2b network based mobility as this would simplify the architecture and operations of EPS networks supporting 3GPP and non-3GPP accesses by using a single mobility protocol. The objective of this work item is to add an S2b based on GTP option according to the conclusions of the feasibility study [10]. It is proposed to apply to the S2b interface the following GTP bearer model. For untrusted non-3GPP access to the EPC the PDN connectivity service is provided by IPsec connectivity between the WLAN UE and the ePDG concatenated with bearer(s) for GTP-based S2b. 12 TTAR-xx.xxxx 기술보고서 WLAN UEs SWu S2b ePDG IPSec GTP Tunnel GTP Tunnel IPSec GTP Tunnel GTP Tunnel GTP Tunnel UL TFT PGW DL TFT One-to-several mapping between one IPSec tunnel and multiple GTP bearers (Default and dedicated bearers) (Figure 5-6) Bearer model on GTP based S2b 5.4. Release 11 5.4.1. S2a Mobility based on GTP and WLAN access to EPC(SaMOG_WLAN) It is triggered by TR 23.852(Study on S2a Mobility based on GTP and WLAN access to EPC - SaMOG) [11]. No usage of WLAN access to EPC over S2a is currently documented in 3GPP specifications whereas deciding whether a non 3GPP access network is to be considered as trusted should not be mandated by the technology of this non 3GPP access. There are requirements from some operators to use GTP or PMIP S2a for WLAN to access EPC. The reasons to use S2a for WLAN to access EPC may vary from operator to operator and depend on the operator’s network deployment policy. One example is that many terminals do not support 3GPP extensions IKEv2/IPsec. Another example is that in some cases the WLAN can be considered secure and it is acceptable for the operator to consider it as trusted by use of S2a to access EPC. Whether GTP or PMIP is used in the network for S2a is transparent to the UE. Upon specifying GTP based S2a for trusted access to EPC, WLAN access to EPC will apply for both GTP and PMIPv6 based interfaces. The objective of this work item is to enable GTPv2 and PMIPv6 based S2a access to EPC through WLAN access. For Trusted non-3GPP access to the EPC, the PDN connectivity is made up of the concatenation of Non-3GPP connectivity(between the UE and the Trusted Non-3GPP access) and of GTP bearer(s) over S2a. The GTP based S2a interface is similar to GTP-S5/S8 and GTP-S2b. The Trusted Non 3GPP access handles the UL TFT received from the PGW over GTP with the same way as an ePDG terminating GTP based S2b handles the UL TFT received from the PGW. Whether GTP or PMIP is used in the 13 TTAR-xx.xxxx 기술보고서 network for S2a is transparent to the UE. Trusted Non3GPP IP Access UE S2 a PGW GTP Tunnel GTP Tunnel GTP Tunnel Non-3GPP connectivity UL TFT DL TFT The mapping between Non-3GPP connectivity and multiple GTP bearers (Default and dedicated bearers) (Figure 5-7) Bearer model on GTP based S2a 5.5. Release 12 5.5.1. WLAN Network Selection for 3GPP Terminals(WLAN_NS) The Hotspot 2.0 solution developed by WFA builds on the architecture and set of protocols defined by IEEE 802.11u and develops key capabilities for network discovery and selection of WLAN terminals based on the ANQP(Access Network Query Protocol) defined in IEEE 802.11u. The Wi-Fi Alliance is working on a certification program that improves WLAN hotspot discovery, network selection, and security. The program leverages the ANQP protocol that is part of IEEE 802.11u(or IEEE 802.11-2012) as well as WPA2 Enterprise security(includes EAP authentication over IEEE 802.1X). 3GPP already has some support for IEEE 802.11u, GAS(Generic Advertisement Service) and ANQP for I-WLAN as per TS 24.234. As Hotspot 2.0 also deals with network selection, there is a need to analyze how a UE can interact with network selection framework of IWLAN, Hotspot 2.0 and ANDSF and specify a consistent procedure for WLAN network selection. The item enhances existing 3GPP solutions for network selection for WLAN networks taking into account WFA Hotspot 2.0 solutions. The proposed work is based on existing TS 23.402 architectures. 3GPP operator's policies for WLAN network selection will be provisioned on 3GPP terminals via pre-configuration or using the ANDSF. The scope of the item includes the followings: 14 TTAR-xx.xxxx 기술보고서 Evaluate existing 3GPP WLAN PLMN and access network selection procedures for 3GPP terminals which use Hotspot 2.0 procedures and provisioned network operator policy(e.g. mechanisms based on WLAN and ANDSF) for any needed changes to current specifications. This may require enhancements to the ANDSF framework. The established 3GPP PLMN network selection(according to TS 23.122) shall not be impacted. The work must ensure there are no conflicts between existing 3GPP PLMN network selection and the 3GPP WLAN PLMN access network selection procedures defined by this WID. Ensure that the content in the Management Object related to 3GPP operator policy provisioning for WLAN network selection procedures and the operator policy provisioning in WFA MO for WLAN network selection are consistent. Identify solutions to resolve potential conflicts between policies provided by non-3GPP providers via Hotspot 2.0 mechanisms and policies provided by 3GPP operators using ANDSF. This wok applies to non-seamless WLAN offload as well as to trusted and untrusted WLAN access to EPC with/without seamless offload [12]. 5.5.2. S2a Mobility based on GTP and WLAN access to EPC(SaMOG) In Release 11, support of GTP & PMIPv6 on S2a for WLAN access was developed without any UE impact but as a consequence with certain limitations on supported functions. In Release 12, this study is aiming at studying enhancements to the Release 11 solution to avoid these limitations(except emergency attach), and deciding which feature & related solution should be developed into normative. In this phase it is expected that there will be some impacts to the UE, although any such impact should be minimized. The SaMOG phase-2 solution supports single-PDN and multi-PDN UEs. The singlePDN UEs support only NSWO or a single PDN connection(with IP address preservation) over a trusted WLAN and the multi-PDN UEs support multiple simultaneous PDN connections over a trusted WLAN, in parallel to NSWO. 15 TTAR-xx.xxxx 기술보고서 5.5.3. Optimized Offloading to WLAN in 3GPP-RAT mobility(WORM) In EPS, ANDSF has defined mechanisms that enable devices to determine which access technology is preferable for certain IP traffic under specific conditions(e.g. through the use of ISRP). In certain scenarios, WLAN access may be considered preferable to certain 3GPP access technologies(e.g. for certain traffic, WLAN may be preferable to UTRAN but not to E-UTRAN). However, at present ANDSF does not provide for mechanisms to indicate preferences with granularity at the 3GPP RAT level within network policies. This restricts the ability for the operator to provide policies that favor a specific 3GPP RAT over another one with reference to the WLAN preference. This study item identifies extensions to ANDSF ISRP and possibly ISMP policies in order to enable policy differentiation of 3GPP RATs(e.g. E-UTRAN vs. UTRAN, GERAN vs. UTRAN) with respect to WLAN. The following key issues are identified [13]: ANDSF WLAN preferences with respect to specific 3GPP RATs Undesired bearer handling Ping-pong offloading to WLAN 5.5.4. WLAN/3GPP Radio Interworking The item was triggered by TR 37.834 [14]. UEs using WLAN networks controlled by 3GPP operators and their partners often make suboptimal offload to/from WLAN decisions resulting in poor user experience and inefficient resource utilization of operator's networks. TSG-RAN agreed that solutions for WLAN/3GPP radio interworking shall support both deployments with and without ANDSF to satisfy different operator deployments. The objective of this work item is to specify mechanism for WLAN/3GPP access network selection and traffic steering that addresses requirements from all operators. Core objectives are to specify mechanism for WLAN/3GPP access network selection and traffic steering. Selected RAN assistance parameters are transferred via system broadcast and/or dedicated signaling are used within: RAN rules in case enhanced ANDSF is not deployed or not supported by the UE 16 TTAR-xx.xxxx 기술보고서 ANDSF policies in case enhanced ANDSF is deployed in the network and supported by the UE RAN assistance information may be enhanced with traffic routing information(e.g. offload granularity) in case ANDSF is not deployed or not supported by the UE. SA2 objectives are to enhance the EPS with improved and operator controlled WLAN/3GPP access network selection and traffic steering including the following specific areas: Support of deployments where the serving PLMN(Home or Visited) is operating with ANDSF policies only or RAN rules only, or with both RAN rules and ANDSF policies. 5.6. Release 13 5.6.1. Multi-RAT joint coordination The coexistence of Multiple RATs introduces many operational coordination problems for network operators. The co-existence of various RATs(i.e. LTE/UMTS/GSM/CDMA/WLAN) is an obvious reality and it will remain relevant in the future. This raises important issues for operators in terms of coordination across the RATs to achieve better user experience(QoE), efficient resource usage, higher network capacity and easier maintenance, especially in a multi-vendor environment. For an operator with multi-RAT networks, frequent updated information from all RATs(radio resource management, mobility and traffic load) is required in order to enable efficient coordination by the network. It will be beneficial to consider a general Multi-RATs coordination from RAN perspective to meet the following requirements: Service aware UE steering between different RATs to provide consistent user experience and user satisfaction, e.g. by connecting to Multi-RATs(e.g. WiFi and LTE). Traffic steering between WAN and WLAN(e.g. LTE and WiFi) Multi RAT joint radio resource coordination for an operator, especially between LTE and GSM, to provide an operator a smooth transition from GSM to LTE, while still keeping basic GSM coverage for e.g. voice or GSM M2M services. Similar migration and spectrum sharing scenarios may also exist for 17 TTAR-xx.xxxx 기술보고서 UMTS/CDMA and LTE Reducing core network impact caused by addition of a new RAT due to interRAT communication This item identifies the general scenarios and requirements for Multi-RAT coordination including LTE, UMTS, GSM, CDMA and WLAN. It also evaluates potential benefits and functionalities for joint operation among different RATs, including the followings [15]: Steering of UEs among different RATs, taking into account service type, user experience, processing capacity, backhaul constraints and/or traffic load, and consequent mobility enhancement Efficient multi RAT joint radio resource coordination to improve load balancing and for an operator to enable, e.g. spectrum re-farming 6. Conclusions This Technical Report presented the technologies and standardization status for 3GPP and WLAN interworking. I-WLAN, which determines how IP-interworking between cellular and non-cellular networks takes place, has been part of 3GPP specifications since Release 6. Session mobility between 3GPP and non-3GPP(such as WLAN) access networks was introduced in Release 8. For both network-based and clientbased mobility between 3GPP and WLAN networks, 3GPP defined the 3GPP to WLAN interfaces: S2a, S2b and S2c. 3GPP also introduced the ANDSF mechanism to provide devices with additional information to expedite discovery and selection based on operator-defined priorities according to management object. 3GPP is taking RAN assistance parameters into consideration for more efficient resource utilization in 3GPP-WLAN interworking. This Technical Report is expected to a reference to develop global standards and lead the markets on the interworking between 3GPP LTE/LTE-A and WLAN. 18 TTAR-xx.xxxx 기술보고서 Appendix Ⅰ References This Technical Report refers to the following documents. [1] 3GPP TR 22.934 Feasibility Study on 3GPP system to Wireless Local Area Network(WLAN) interworking [2] 3GPP TS 22.234 Requirements on 3GPP system to Wireless Local Area Network(WLAN) interworking [3] 3GPP TS 23.234 3GPP System to Wireless Local Area Network(WLAN) interworking; System description [4] 3GPP TS 23.327 Mobility between 3GPP-WLAN interworking and 3GPP systems [5] 3GPP TR 22.937 Requirements for service continuity between mobile and Wireless Local Area Network(WLAN) networks [6] 3GPP TS 24.312 Access Network Discovery and Selection Function(ANDSF) Management Object(MO) [7] 3GPP TR 23.861 Study on Multi Access PDN Connectivity and IP Flow Mobility [8] 3GPP TS 22.278 Service requirements for the Evolved Packet System(EPS) [9] 3GPP TS 23.402 Architecture enhancements for non-3GPP accesses [10] 3GPP TR 23.834 Study on S2b mobility based on GTP [11] 3GPP TR 23.852 Study on S2a Mobility based on GTP and WLAN access to EPC [12] 3GPP TR 23.865 WLAN Network Selection for 3GPP Terminals [13] 3GPP TR 23.890 Study on Optimized Offloading to WLAN in 3GPP-RAT Mobility [14] 3GPP TR 37.834 Study on WLAN/3GPP Radio Interworking [15] 3GPP TR 37.870 Study on Multi-RAT Joint Coordination 19 TTAR-xx.xxxx 기술보고서 영문 기술보고서 해설서 1. 개요 전용망을 사용하는 이동통신 사업자 입장에서 WLAN 은 급증하는 무선 트래픽을 수용하기 위한 하나의 중요한 수단으로 활용할 수 있다. 3GPP 는 3GPP 시스템내에서 자원 활용 및 서비스 접근성을 제공하는 I-WLAN(Interworking WLAN) 기능을 정의하고 있으며, 보조적인 무선 접속 기술로 활용하기 위해 3GPP-WLAN 상호 운용 기능을 제공하고 있다. 3GPP 는 Release 6 부터 WLAN 엑세스망을 통해 3GPP 서비스 제공이 가능하도록 아키텍쳐와 관련 기능을 정의하였으며, Release 8 에서는 3GPP 엑세스망과 WLAN 사이의 Seamless 핸드오버와 서비스 연속성 기능을 정의하였다. Release 10 이후에는 3GPP 네트워크내에서 WLAN 을 지원하기 위한 좀더 진화된 기술을 정의하고 있다. 본 기술보고서는 3GPP 망과 WLAN 사이의 상호 운용에 관련된 기술과 표준 동향을 소개하며, 앞으로의 3GPP LTE/LTE-A 망과 WLAN 등의 이종망 간 연동에 관한 국제 표준 및 시장 동향을 예측하고 대응하기 위한 참고 문서로 활용되기를 기대한다. 2. 기술보고서의 구성 및 범위 본 기술보고서는 3GPP 기술 표준 및 기술보고서를 기반으로한 Seamless 핸드오버와 트래픽 스티어링 기술을 포함하여, 3GPP-WLAN 상호 운용에 관한 3GPP Release 6 부터 Release 13 까지의 표준 현황을 소개한다. 3. 참조 표준(권고) - 해당 사항 없음. 20 TTAR-xx.xxxx 기술보고서 4. 용어 정의 및 약어 4.1. 용어 정의 4.1.1. Evolved Packet System 다양한 무선 엑세스 기술을 지원하며, 고속의 데이터 전송률, 저지연, 패킷 기반 전송 등의 특징을 갖는 3G UMTS 의 진화된 시스템으로 Evolved Packet Core(EPC)와 Evolved Radio Access Network(E-UTRAN)으로 구성됨. 4.1.2. Interworking WLAN(I-WLAN) 3GPP 시스템과 상호 운용하는 WLAN 4.1.3. 3GPP-WLAN Interworking 3GPP 시스템과 WLAN 기반 표준 기술과의 상호 운용 5. 3GPP-이종망 연동 표준 기술 Release 6 의 ‘WLAN-UMTS Interworking’에서는 3GPP-WLAN 상호 운용에 관한 서비스 시나리오와 요구사항을 정의한다. Release 8 의 ‘I-WLAN Network Selection Principle’에서는 WLAN UE 의 PLMN 네트워크 선택 절차를 정의한다. ‘Mobility between 3GPP-WLAN Interworking and 3GPP Systems’에서는 I-WLAN 과 3GPP 시스템 사이의 이동성 지원을 위한 시스템을 기술하며, DSMIPv6 기반의 기술적 해법을 정의한다. ‘Service continuity between mobile and WLAN networks’에서는 GSM/GPRS/3G 망과 WLAN 망사이의 Seamless 로밍과 서비스를 위한 요구사항을 정의한다. ‘Access Network Discovery and Selection Function(ANDSF)’에서는 정책 기반의 네트워크 발견 및 선택을 지원하기 위한 ANDSF 아키텍쳐와 관련 절차를 정의한다. Release 10 의 ‘IP Flow Mobility and seamless WLAN offload(IFOM)’에서는 IP flow 기반의 Seamless WLAN 오프로딩 기법을 소개한다. ‘S2b Mobility based on GTP(SMOG)’에서는 S2b 인터페이스로 정의된 E-UTRAN 과 untrusted non-3GPP access 간의 이동성을 지원하기 위한 GTP bearer 모델을 정의한다. 21 TTAR-xx.xxxx 기술보고서 Release 11 의 ‘S2a Mobility based on GTP and WLAN access to EPC(SaMOG_WLANB)’에서는 S2a 인터페이스로 정의된 E-UTRAN 과 trusted non-3GPP access 간의 GTP bearer 모델을 정의한다. Release 12 의 ‘WLAN Network Selection for 3GPP Terminals(WLAN_NS)’에서는 WFA 의 Hotspot 2.0 을 고려한 개선된 WLAN 네트워크 선택 기법을 소개한다. ‘S2a Mobility based on GTP and WLAN access to EPC(SaMOG)’에서는 Release 11 의 UE 제약사항을 개선한 해법을 제시한다. ‘Optimized Offloading to WLAN in 3GPP-RAT mobility(WORM)’에서는 3GPP RAT(E-UTRAN, UTRAN, GERAN)을 구분하는 개선된 ANDSF 기법을 제시한다. ‘WLAN/3GPP Radio Interworking’에서는 무선 엑세스 환경이 반영된 WLAN/3GPP 망 선택 기법을 정의한다. Release 13 의 ‘Multi-RAT joint coordination’에서는 LTE, UMTS, GSM, CDMA, WLAN 등의 다중 엑세스 기술의 통합 운용을 위한 일반적인 시나리오와 요구사항을 정의한다. 6. 결론 본 기술보고서에서는 3GPP 망과 WLAN 등의 이종망간의 상호 운용을 위한 기술과 Release 13 까지의 3GPP 표준 동향을 정리하였다. 부록 Ⅰ. 참고 문헌 본 기술보고서에서 참조한 3GPP 기술 규격 및 기술 보고서 목록을 나열한다. 22 TTAR-xx.xxxx 기술보고서 기술보고서 작성 공헌자 기술보고서 번호 : TTAR-xx.xxxx 이 기술보고서의 제정개정 및 발간을 위해 아래와 같이 여러분들이 공헌하였습니다. 구분 성명 위원회 및 직위 연락처 소속사 박병성 PG 908 부의장 [email protected] 에릭슨엘지 [email protected] 에릭슨엘지 기술보고서(과제) 외 프로젝트그룹 제안 위원 기술보고서 초안 박병성 작성자 기술보고서 초안 에디터 기술보고서 초안 외 프로젝트그룹 위원 박병성 PG 908 부의장 [email protected] 에릭슨엘지 이형호 PG908 의장 [email protected] ETRI [email protected] LG 전자 외 프로젝트그룹 검토 기술보고서안 위원 오민석 심의 사무국 담당 PG 908 부의장 TC9 의장 외 기술위원회 위원 김대중 TTA 사무국 김은교 TTA 사무국 이수진 TTA 사무국 031-724-0090 [email protected] 031-724-0098 [email protected] 031-724-0093 [email protected] 23 TTA TTA TTA TTAR-xx.xxxx 기술보고서 3GPP 이종망 연동 기술 표준 분석(기술보고서) (3GPP Standardization Status for Inter-operability with other RATs(Technical Report)) 발행인 : 한국정보통신기술협회 회장 발행처 : 한국정보통신기술협회 463-824, 경기도 성남시 분당구 분당로 47 Tel : 031-724-0114, Fax : 031-724-0109 발행일 : 20xx.xx.