SAE / EPC from A - Z INACON GmbH Kriegsstrasse 154 76133 Karlsruhe Germany www.inacon.com e-mail: inacon@inacon.de Cover design by Stefan Kohler © 1999 - 2009 INACON GmbH Kriegsstrasse 154 76133 Karlsruhe All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted by any means, electronic, mechanical, photocopying, recording, or otherwise, without written permission from the publisher. No patent liability is assumed with respect to the use of the information contained herein. Although every precaution has been taken in the preparation of this publication, the publisher and authors assume no responsibility for errors or omissions. Neither is any liability assumed for damages resulting from the use of the information contained herein. For more information, contact INACON GmbH at www.inacon.com. Legend: All INACON publications use the same color codes to distinguish mandatory from optional or conditional parts in frame formats or optional from mandatory data blocks or signaling messages in scenarios. The different color codes are explained underneath: • Color Codes in Frame Formats: • Color Codes in Scenarios: Foreword of the Publisher: Dear Reader: Note that this book is primarily a training document because the primary business of INACON GmbH is the training and consulting market for mobile communications. As such, we are proud to providing high-end training courses to many clients worldwide, among them operators like Cingular, Mobilkom Austria, SWISSCOM, T-MOBILE or VSNL (India) and equipment suppliers like ALCATEL-LUCENT, ERICSSON and SONY-ERICSSON, MOTOROLA, NOKIA-SIEMENS and RIM. INACON GmbH is not one of the old-fashioned publishers. 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Sincerely, Gunnar Heine / President & CEO of INACON GmbH Table of Content Assessment & Top Level View 1 1.1 Why is an Architecture Evolution necessary? 2 1.1.1 Integration of E-UTRAN with its new Concepts 3 1.1.2 Integration of Non-3GPP RAT's is sub-optimum in Rel. 7 because 4 1.1.3 Therefore, legacy operators of Non-3GPP-RAT's cannot adopt the existing 3GPP-CN-Architecture 4 1.2 Important Requirements on SAE according to 3GPP 6 1.2.1 Coexistence 7 1.2.2 Service Continuation 8 1.2.3 Better Performance 8 1.2.4 Support of any Radio Access Technology (RAT) 11 1.2.5 Circuit-switched fallback 12 1.2.6 Management of Access Networks 12 1.2.1 Comprehension Check & Exercise: Reasons of a System Architecture Evolution? 14 1.3 Seamless Mobility Options and their Characteristics 16 1.3.1 Intra-RAT Mobility 17 1.3.2 Inter-RAT Mobility (w/o Optimizations) 18 1.3.3 Inter-RAT Mobility (with Optimizations) 18 1.4 Architecture Overview 20 1.4.1 Evolved Packet Core in Context 20 1.4.1.1 EPC vs. EPS 20 1.4.1.2 Non-3GPP Access Networks (trusted / non-trusted) 21 1.4.2 Zoom into the EPS 22 1.4.2.1 Functional Overview of Core Network Elements within the EPC. .23 1.4.3 Network Elements and their Functions within the EPC 24 1.4.3.1 Mobility Management Entity (MME) 24 1.4.3.1.1 Characteristics 24 1.4.3.1.2 Identification 24 1.4.3.1.3 Interfaces & Protocols 26 1.4.3.1.4 Tasks & Functions of the MME 28 1.4.3.1.4.1 NAS-Signaling towards the UE 28 1.4.3.1.4.2 S1-Signaling towards the eNodeB 28 1.4.3.1.4.3 S-GW and P-GW Selection 30 1.4.3.1.4.4 Other Selection Functions 31 1.4.3.1.4.4 Local Breakout 32 1.4.3.1.4.5 IMS and Local Breakout 32 1.4.3.2 Serving Gateway (S-GW) 34 1.4.3.2.1 Characteristics 34 1.4.3.2.2 Identification 34 1.4.3.2.3 Interfaces & Protocols 36 Table of Content © INACON GmbH 1999 - 2009. 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Version Number 2.000 - i - 1.4.3.2.4 Tasks & Functions of the S-GW 38 1.4.3.2.4.1 Packet Routing / Relaying 38 1.4.3.2.4.2 Legal Interception 38 1.4.3.2.4.3 QCI-based Packet Tagging 38 1.4.3.2.4.4 Accounting 38 1.4.3.3 PDN Gateway (P-GW or PDN-GW) 40 1.4.3.3.1 Characteristics 40 1.4.3.3.2 Identification 40 1.4.3.3.3 Interfaces & Protocols 42 1.4.3.3.4 Tasks & Functions of the P-GW 44 1.4.3.3.4.1 UE IP Address Allocation 44 1.4.3.3.4.2 QCI-based Packet Tagging 44 1.4.3.3.4.3 Policy Enforcement 44 1.4.3.3.4.4 Legal Interception 45 1.4.3.3.4.5 Home Agent Function 45 1.4.3.4 enhanced Packet Data Gateway (ePDG) 46 1.4.3.4.1 Characteristics 46 1.4.3.4.2 Identification 46 1.4.3.4.3 Interfaces & Protocols 48 1.4.3.4.4 Tasks & Functions of the ePDG 50 1.4.3.4.4.1 ESP-Tunnel Mgmt towards UE's 50 1.4.3.4.4.2 QoS-specific Packet Tagging in UL-Direction 50 1.4.3.4.4.3 Legal Interception 50 1.4.3.4.4.4 MAG-Function for PMIPv6 50 1.4.3.5 Protocol Stack Architecture on the UE-Side 52 1.4.4 Comprehension Check & Exercise: Interworking within the EPS-Architecture 54 Operations Overview 57 2.1 Network Access to the EPC in case of 3GPP-RAT's 58 2.1.1 E-UTRAN 58 2.1.1.1 Related Network Architecture 58 2.1.1.2 Related Network Elements 58 2.1.1.3 Signaling and Important State Changes (EMM, ECM, ESM) 60 2.1.2 GERAN / UTRAN 62 2.1.2.1 Related Network Architecture 62 2.1.2.1.1 Selection of EPC vs. GGSN 62 2.1.2.2 Signaling Procedures (GMM/PMM, SM) 64 2.1.1.4 Comprehension Check & Exercise: Relate E-UTRAN Procedures to GERAN / UTRAN Procedures 66 2.2 Network Access in case of Non-3GPP RAT's 68 2.2.1 Network Discovery and Selection 68 2.2.1.1 Problem Description 68 2.2.1.2 Interworking with the ANDSF 70 2.2.1.3 Distinction Trusted vs. Non-Trusted Non-3GPP RAT's 72 2.2.2 Trusted Non-3GPP RAT's 74 2.2.2.1 Related Network Architecture 74 2.2.2.2 Signaling Procedures if EAP and PMIPv6 are used 76 2.2.2.3 Signaling Procedures if MIPv4 is used 78 2.2.3 Non-Trusted Non-3GPP RAT's 80 2.2.3.1 Related Network Architecture 80 2.2.3.2 Signaling Procedures if IKEv2 and PMIPv6 are used 82 SAE / EPC from A - Z © INACON GmbH 1999 - 2009. 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Version Number 2.000 - ii - 2.2.3.3 Signaling Procedures if IKEv2 and DSMIPv6 are used 84 2.3 Voice Call Establishment 86 2.3.1 IMS-based 86 2.3.1.1 Related Network Architecture 86 2.3.1.2 Signaling Procedure (SIP, SDP, DIAMETER) 88 2.3.2 Circuit-switched Fallback 90 2.3.2.1 Related Network Architecture 90 2.3.2.2 Signaling Procedure for MOC 92 2.3.2.3 Comprehension Check & Exercise: Voice Call Establishment 94 2.4 Macro Mobility / Inter-RAT Roaming 96 2.4.1 Handover E-UTRAN to Trusted Non-3GPP RAT 96 2.4.1.1 Related Network Architecture 96 2.4.1.2 Signaling Procedure (NBM / PMIPv6 on S2a) 98 2.4.2 Handover E-UTRAN to Non-Trusted Non-3GPP RAT 100 2.4.2.1 Related Network Architecture 100 2.4.1.2 Signaling Procedure (NBM / PMIPv6 on S2b) 102 2.4.1.3 Comprehension Check & Exercise: Inter-RAT Mobility 104 Architectural Details of the EPS 107 3.0 Comprehension Test & Repetition: Network Interfaces and Protocols 108 3.1 Network Layout and Important Identifiers 114 3.1.1 Organization of the E-UTRAN 114 3.1.1.1 Tracking Areas 115 3.1.1.1.1 TAI and TAI-list 116 3.1.1.2 E-UTRAN Pool Areas 116 3.1.2 MME Pool's and MMEI 116 3.1.1.3 S-GW Service Areas 118 3.1.3 Identifiers of the UE 120 3.1.3.1 M-TMSI and S-TMSI 120 3.1.3.2 GUTI 122 3.2 Bearer Concept & QoS-Architecture in SAE 124 3.2.1 SAE-Bearers, Classification and Policy Enforcement 124 3.2.2 The QoS-Profile of the SAE-Bearer 126 3.2.2.1 GBR - Guaranteed Bit Rate 127 3.2.2.2 MBR - Maximum Bit Rate 127 3.2.2.3 AMBR - Aggregate Maximum Bit Rate 127 3.2.2.4 ARP - Allocation Retention Priority 127 3.2.2.5 QCI-Values and their Meanings 128 3.2.2.6 Mapping between Rel. 8 QoS and earlier Releases 128 3.2.3 QoS-Architecture with Release 8 130 3.2.3.1 PCRF (Policy and Charging Rules Function) 130 3.2.3.2 BBERF (Bearer Binding and Event Reporting Function) 130 3.2.3.3 PCEF (Policy and Charging Enforcement Function) 130 3.2.3.4 AF (Application Function) 130 3.2.3.5 SPR (Subscription Profile Repository) 132 Table of Content © INACON GmbH 1999 - 2009. 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Version Number 2.000 - iii - 3.2.3.6 OCS (Online Charging System) 132 3.2.3.7 OFCS (Offline Charging System) 132 3.2.4 Bearer Establishment & Authorization - Differences Rel. 8 vs former Releases 134 3.2.5 Relationship and Dependency among the different Bearers 136 Protocol Suite 139 4.1 The “Mainstream” Protocol Stacks 140 4.1.1 Control Plane / E-UTRAN - EPC 140 4.1.2 User Plane E-UTRAN – EPC (S5/S8 GTP-based) 142 4.1.3 User Plane E-UTRAN – EPC (S5/S8 PMIPv6/GRE-based) 144 4.2 Generic Protocols within the EPC-Environment 146 4.2.1 IPv4 and IPv6 and their Differences 146 4.2.1.1 Headers and IP-Address Ranges 146 4.2.1.2 How to obtain an IP-Address 148 4.2.1.2.1 IPv4 and DHCP 148 4.2.1.2.2 IPv6 and “Stateless Autoconfiguration” 150 4.2.1.2.3 Real-Life Recording: Stateless Autoconfiguration 152 4.2.1.3 Fragmentation in IPv4 and IPv6 154 4.2.2 QoS in IP-Networks 156 4.2.2.1 DiffServ 156 4.2.2.1.1 Details of the AF(X,Y) PHB (Assured Forwarding) 158 4.2.2.1.2 Details of the EF PHB (Expedite Forwarding) 160 4.2.3 SCTP 162 4.2.3.1 Important SCTP-Functions 162 4.2.3.2 Example of an SCTP-Packet 164 4.2.4 DIAMETER 166 4.3 Protocols related to E-UTRA Networks 168 4.3.1 EPS Mobility Management (EMM) 168 4.3.1.1 Important EMM-Procedures 168 4.3.1.1.1 Common Procedures 169 4.3.1.1.2 Specific Procedures 169 4.3.1.1.3 Connection Management Procedures 169 4.3.1.2 State Machine 170 4.3.2 EPS Session Management (ESM) 172 4.3.2.1 Important ESM-Procedures 172 4.3.2.1.1 MME-initiated 173 4.3.2.1.2 UE-initiated 173 4.3.2.2 State Machine 174 4.3.3 Radio Resource Control RRC 176 4.3.3.1 Overview 176 4.3.3.1.1 Transmission of broadcast information 177 4.3.3.1.2 Establish and maintain services 177 4.3.3.1.3 QoS control 177 4.3.3.1.4 Transfer of dedicated control information 177 4.3.3.2 State Characteristics of RRC 178 4.3.3.2.1 RRC_IDLE 178 4.3.3.2.2 RRC_CONNECTED 178 SAE / EPC from A - Z © INACON GmbH 1999 - 2009. All rights reserved. Reproduction and/or unauthorized use of this material is prohibited and will be prosecuted to the full extent of German and international laws. Version Number 2.000 - iv - 4.3.4 Packet Data Convergence Protocol (PDCP) 180 4.3.4.1 Overview 180 4.3.4.1.1 RoHC 180 4.3.4.1.2 Numbering of PDCP PDU’s 180 4.3.4.1.3 In-sequence delivery of PDU’s 180 4.3.4.1.4 Duplicate deletion 180 4.3.4.1.5 Encryption 181 4.3.4.1.6 Integrity Protection 181 4.3.4.2 Structure of PDCP PDU 182 4.3.5 The S1-AP Protocol 184 Call Flows & Scenarios 187 5.1 Attachment through E-UTRAN / new MME 188 5.2 Tracking Area Update 194 5.1.1 Inter MME tracking area update 194 5.1.2 Intra MME tracking area update 195 5.3 PDP Context Establishment 196 5.4 Inter MME Handover 200 Table of Content © INACON GmbH 1999 - 2009. All rights reserved. Reproduction and/or unauthorized use of this material is prohibited and will be prosecuted to the full extent of German and international laws. Version Number 2.000 - v - Chapter 1: Assessment & Top Level View Objectives Some of your questions that will be answered during this session… • Why is there a system architecture evolution in the first place? • Which improvements does SAE yield? • What are the requirements according to 3GPP? • Is it possible to obtain just an overview of the new architecture? • How will the protocol architecture of a typical UE look like? • Which potential improvements are not covered by the SAE? Assessment & Top Level View 1 - 1 - © INACON GmbH 1999 - 2009. All rights reserved. Reproduction and/or unauthorized use of this material is prohibited and will be prosecuted to the full extent of German and international laws. Version Number 2.000 [...]... Mobility Management Entity takes care of various control plane functions like mobility management and session management • The S-GW or Serving Gateway is the peer of the MME within the user plane and its functions evolve around packet data routing and forwarding • 1 The PDN-Gateway has similar functions as the Serving Gateway but it remains the anchor during a packet data connection even if MME and S-GW... link may be released 1.3.3 Inter-RAT Mobility (with Optimizations) • Optimizations always relate to additional specifications that govern mobility related information exchange between the UE and the network • This information exchange typically only occurs while a radio link exists and relates to the transfer of measurement data and handover information • Therefore, optimized inter-RAT mobility can only... German and international laws Version Number 2.000 -3- SAE / EPC from A - Z 1 • Low Latency Requirements • E-UTRAN imposes specific maximum latencies to be achieved for state changes within the E-UTRAN control plane (e.g from RRC-idle to RRCconnected) and, even more important, during the traversal of user data through the user plane • In that respect, for the control plane state change latencies of app... that takes care of control plane tasks • The MME may physically be part of an SGSN or S-GW or it may be setup as a stand-alone network element MME's are typically organized in pool areas (S1Flex) to provide for load balancing among the MME's which belong to the same pool All eNodeB's which belong the related E-UTRAN pool areas shall have access to the MME's belonging to this MME-pool area(s) [3GTS 23.002... those gaps but it took years and a considerable expenses which have to be settled among less shoulders 1 Room for your Notes: • Abbreviations of this Section: AAA Authentication, Authorization and Accounting PCRF Policy and Charging Rules Function (3GTS 23.203) E-UTRAN Evolved UMTS (Universal Mobile Telecommunication System) Terrestrial Radio Access Network QoS Quality of Service e2e End-to-End RAT Radio... exceeds by far any other implementation in the market Their price and stability prospers quite a bit from the related volume of scales effects The other possibility has clearly been shown during recent years in the WiMAXarea: The IEEE had only defined the air interface and therefore, a core network and all protocols and procedures were missing It was finally the WiMAX-forum that jumped in and filled... 1 Abbreviations of this Section: 3G 3rd Generation GWCN GateWay Core Network configuration 3GPP Third Generation Partnership Project (Collaboration between different standardization organizations (e.g ARIB, ETSI) to define advanced mobile communications standards, responsible for UMTS) LTE Long Term Evolution (of UMTS) 3GTS 3rd Generation Technical Specification MOCN Multi-Operator Core Network ANDSF... prohibited and will be prosecuted to the full extent of German and international laws Version Number 2.000 1 - 15 - SAE / EPC from A - Z 1 1.3 Seamless Mobility Options and their Characteristics The objectives of this section are to illustrate the different variations of mobility and how they are implemented as part of the SAE Key points of this section are that: 1 Which mobility options are supported by a. .. Reproduction and/or unauthorized use of this material is prohibited and will be prosecuted to the full extent of German and international laws Version Number 2.000 - 17 - SAE / EPC from A - Z 1 1.3.2 Inter-RAT Mobility (w/o Optimizations) • Generically, inter-RAT mobility is frequently called macro-mobility This process relates to the change of the radio access technology e.g from WiFi to E-UTRAN • Typically,... ms are the target • User data shall be delayed by no more than 5 ms in the ideal case when traversing through E-UTRAN Note that this value does not take into account latencies within the EPC or beyond!"Packet-switched only" requires a serious QoS-integration with respect to e2e-integration and service differentiation The full-scale integration of QoS is a precondition for the operation of any carriergrade . contact INACON GmbH at www.inacon.com. Legend: All INACON publications use the same color codes to distinguish mandatory from optional or conditional parts in frame formats or optional from mandatory. through e-mail (inacon@inacon.de), if you have any questions. All our authors are employees of INACON GmbH and all of them are proven experts in their area with usually many years of practical experience. The. information about virtually every parameter, timer and detail of this technology. • Incorporation of several practical exercises. • If applicable, incorporation of examples from our practical field