LTE from A-Z - Technology and Concepts of the 4G 3GPP Standard 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 Principles and Motivation of LTE 1 1.1 Mobile Radio: Comparison between 3G and 4G 2 1.1.1 Performance and Mobility Management related Issues 2 1.1.2 Architecture related Issues 4 1.1.3 Procedure and Radio related Issues 6 1.2 Requirements on LTE 8 1.2.1 General Requirements 8 1.2.1.1 Support of Enhanced Quadruple Play Services 10 1.2.1.2 Very High Data Rates @ flexible bandwidth deployment ((1.25) 5 – 20 MHz) 10 1.2.1.3 AIPN and PS services only 10 1.2.2 Important Characteristics of LTE Physical Layer 12 1.2.2.1 General Physical Layer Characteristics 12 1.2.2.1.1 OFDM 12 1.2.2.1.2 Scalable Bandwidth 13 1.2.2.1.3 Smart Antenna Technology 14 1.2.2.1.4 Fast scheduling and AMC 14 1.2.2.1.5 No Soft(er) handover 14 1.2.3.2 OFDM/OFDMA 16 1.2.3.2.1 Traditional narrowband communication 16 1.2.3.2.2 Problems for wideband signals 17 1.2.3.2.3 OFDM 17 1.2.3.2.4 OFDM and OFDMA 17 1.2.3.2.5 LTE and OFDM 17 1.2.3.3 Smart Antenna Technology in LTE 18 1.2.3.3.1 Categorization of Smart Antenna Technologies 18 1.2.3.3.1.1 SISO 18 1.2.3.3.1.2 SIMO 18 1.2.3.3.1.3 MISO 19 1.2.3.3.1.4 MIMO 19 1.2.3.3.2 Multiple Input Multiple Output (MIMO) 20 1.2.3.3.2.1 Multiple carrier technology 21 1.2.3.3.2.2 MIMO 21 1.2.3.3.3 Adaptive Antenna Systems (AAS) 22 1.2.3.3.3.1 Signal generation 23 1.2.3.3.3.2 Constructive superimposition at the intended receiver 23 1.2.3.3.3.3 Destructive superimposition at the not intended receiver 23 1.2.3.3.3.4 Generation of signals for multiple UE’s 23 1.2.3.4 Macro Diversity exploitation by SFN 24 1.2.3.4.1 Requirements for MBMS services 24 1.2.3.4.2 MBMS operation with a SFN 24 1.2.3.4.3 SFN for point to point services 25 1.2.3.5 The Frequency Bands Intended for LTE 26 1.2.3.5.1 Exclusive usage 27 1.2.3.5.2 Refarming 27 1.2.3.5.3 Licensed operation 27 1.2.3.5.4 Unlicensed operation 27 1.2.3.6 Flexible Bandwidths, Parameters 28 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 2.030 - i - 1.2.3.6.1 Fixed subcarrier separation 28 1.2.3.6.2 Usage of carriers in the middle of the bandwidth for PBCH and synchronization signals 29 1.2.3.6.3 Deployment Scenarios 30 1.2.4 Important Characteristics of the LTE Layer 2 and 3 32 1.2.4.1 Support of the new LTE L1 32 1.2.4.2 Simple IP centric protocols supporting AIPN 32 1.2.4.3 Support of various inter RAT handovers (GSM, UTRA, etc.) 33 1.3 LTE and System Architecture Evolution (SAE) 34 1.3.1 Overview 34 1.3.1.1 Missing RNC 34 1.3.1.2 Interconnected eNB’s 35 1.3.1.3 Separate entities for user plane and control plane in the EPC 36 1.3.1.4 Combined Serving Gateway and MME 36 1.3.1.5 Combined Serving and PDN Gateways 36 1.3.1.6 S1-flex 36 1.3.1.7 Used legacy elements 36 1.3.1.8 Roaming case 36 1.3.1.9 Direct Tunnel 36 1.3.1.10 EPS, EPC, E-UTRAN & LTE, SAE 36 1.3.2 The eNB 38 1.3.2.1 Selection of MME at attachment 39 1.3.2.2 Scheduling of paging messages 39 1.3.2.3 Routing of user plane data to Serving GW 40 1.3.2.4 PDCP 40 1.3.2.5 RRM/RRC 40 1.3.2.6 RLC 40 1.3.2.7 MAC 40 1.3.2.8 Complete L1 functionality 40 1.3.3 The MME 42 1.3.3.1 NAS signalling 42 1.3.3.2 Inter CN node signaling (3GPP networks) 42 1.3.3.3 Security management 42 1.3.4 The Serving GW 44 1.3.4.1 Termination of U-plane packets for paging reasons 44 1.3.4.2 Support of UE mobility anchoring by switching U-plane during inter eNB handover 44 1.3.4.3 Transport Packet Marking According to QCI 45 1.3.4.4 Mobility anchoring for inter-3GPP mobility 45 1.3.4.5 Packet routing and forwarding 45 1.3.4.6 Charging support 45 1.3.4.7 Lawful interception 45 1.3.5 The PDN GW 46 1.3.5.1 Termination towards of PDN’s 46 1.3.5.2 Policy enforcement 46 1.3.5.3 Charging support 46 1.3.5.4 DHCPv4 and DHCPv6 functions 47 1.3.6 Identifiers of the UE and the Network Elements 48 1.3.6.1 PLMN ID 50 1.3.6.2 EPS Bearer ID 50 1.3.6.3 MMEI 50 1.3.6.4 GUMMEI 50 1.3.6.5 Physical Cell ID 50 LTE from A-Z © INACON GmbH 1999 - 2009. 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Version Number 2.030 - ii - 1.3.6.6 eNB/cell ID 50 1.3.6.7 TAI 50 1.3.6.8 C-RNTI 50 1.3.6.9 RA-RNTI 50 1.3.6.10 SI-RNTI 50 1.3.6.11 P-RNTI 50 1.3.6.12 Random Value 50 1.3.6.13 IMSI, S-TMSI, and IMEI 52 1.3.6.14 GUTI 52 1.3.6.15 eNB S1-AP UE ID and MME S1-AP UE ID 52 1.4 The E-UTRAN Protocol Stack 54 1.4.1 Control Plane Protocol Stack 54 1.4.1.1 Air Interface protocols 55 1.4.1.2 NAS protocols 56 1.4.2 User Plane Protocol Stack 58 1.4.2.1 Air Interface protocols 58 1.4.2.2 S1 protocol 58 1.4.3 X2 Interface Control Plane Protocol Stack 60 1.4.4 X2 User Plane Protocol Stack 62 1.5 Overview Channels of E-UTRAN 64 1.5.1 Channel Types 64 1.5.1.1 Logical Channels 64 1.5.1.2 Transport Channels 64 1.5.1.3 Physical Channels 65 1.5.2 Logical Channels of E-UTRAN 66 1.5.2.1 BCCH 66 1.5.2.2 PCCH 66 1.5.2.3 CCCH 66 1.5.2.4 MCCH 66 1.5.2.5 DCCH 67 1.5.2.6 DTCH 67 1.5.2.7 MTCH 67 1.5.3 Transport Channels of E-UTRAN 68 1.5.3.1 RACH 68 1.5.3.2 UL-SCH 68 1.5.3.3 BCH 68 1.5.3.4 PCH 68 1.5.3.5 MCH 69 1.5.3.6 DL-SCH 69 1.5.4 Physical Channels of E-UTRAN 70 1.5.4.1 PBCH 70 1.5.4.2 PDCCH 70 1.5.4.3 PCFICH 71 1.5.4.4 PUCCH 71 1.5.4.5 PRACH 71 1.5.4.6 PHICH 72 1.5.4.7 PDSCH 72 1.5.4.8 PMCH 72 1.5.4.9 PUSCH 72 1.5.4.10 Downlink reference signal 72 1.5.4.11 Primary and secondary synchronization signal 72 1.5.4.12 Uplink reference signal or UL pilot symbol 72 1.5.4.13 Uplink sounding signal 72 Table of Content © INACON GmbH 1999 - 2009. 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Version Number 2.030 - iii - 1.5.4.14 Random Access Preamble 72 1.5.5 Mapping of Channels in E-UTRAN 74 1.6 Key Development Trends manifested in LTE 76 1.6.1 Mapping of User Plane Packets to the Resources 76 1.6.1.1 Method 1: Fast resource allocation on optimum resources 77 1.6.1.2 Method 2: Slow resource allocation on suboptimum resources 78 1.6.1.3 GSM 78 1.6.1.4 WCDMA 78 1.6.1.5 HSPA 78 1.6.1.6 LTE 78 1.6.1.7 General trend 78 1.6.2 All IP Network and Simple Packet Service Driven Protocols 80 1.6.2.1 Reduced User Plane Latency 82 1.6.2.1 Reduced Control Plane Latency 84 1.7 LTE Key Feature Summary 86 1.7.1 Air Interface Technology 86 1.7.2 System Architecture 87 1.7.3 Service Aspects 87 Key Technologies of the LTE Physical Layer 89 2.1 Introduction OFDM Technology 90 2.1.1 Impact of Orthogonality in the Frequency Domain – 3 Steps 90 2.1.2 Practical Exercise: Physical Basics of OFDM / OFDMA 96 2.1.3 Practical Exercise: Scaling of OFDM / OFDMA-Systems 98 2.1.4 The In-Phase – Quadrature (I/Q) Presentation 100 2.1.5 OFDM / OFDMA and IFFT 102 2.1.5.1 Considering the Discrete Oscillator Array Option 103 2.1.5.2 Details of the IFFT Option 103 2.1.5.3 Why is it called F a s t Fourier Transformation? 103 2.1.6 Modulation Scheme Overview 104 2.1.8 Tackling Inter-Symbol Interference (ISI) 108 2.1.8.1 Introduction 108 2.1.8.1.1 Delay Spread 108 2.1.8.2 Cyclic Prefix 110 2.1.8.2.1 Variable Duration and other Assets of the Cyclic Prefix 111 2.1.8.2.2 Cyclic Prefix in OFDMA in LTE 111 2.1.9 Layout of a Typical OFDM System 112 2.1.9.1 Remarks on the Brick Wall Image 113 2.1.9.2 Subchannelization 113 2.1.9.3 Pilot Subcarriers 113 2.1.9.4 Null Subcarriers 113 2.2 Introduction to MIMO Technology 114 2.2.1 The Basics: Signal Fading Physics between TX and RX 114 2.2.2 Multiplexing Dimensions 116 2.2.2 Multiplexing Dimensions 118 2.2.3 The Multipath Dimension 120 2.2.6 MIMO General Operation 122 The Physical Layer of E-UTRAN 125 3.1 The Use of OFDM/OFDMA in LTE 126 LTE from A-Z © INACON GmbH 1999 - 2009. 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Version Number 2.030 - iv - 3.1.1 Frame Structure 126 3.1.1.1 The generic frame structure 126 3.1.1.2 The downlink slots 127 3.1.1.3 The uplink slots 127 3.1.1.4 The frame structure type 2 127 3.1.2 LTE Parameters 128 3.1.2.1 The normal configuration 128 3.1.2.2 The extended configuration with 15 kHz subcarrier separation 128 3.1.2.3 The extended configuration with 7.5 kHz subcarrier separation 129 3.1.2 Resource Element and Resource Block Definition 130 3.1.2.1 Definition Resource Element 130 3.1.2.2 Definition Resource Block 130 3.1.2.3 Definition Subframe 130 3.1.2.4 Number of resource blocks in a given bandwidth 131 3.1.3 Choice of the UL Transmission Scheme (UL Data Symbols only) 132 3.1.3.1 What would happen if OFDM would be used in the UL 133 3.1.3.2 SC-FDMA is used for the UL 133 3.1.4 FDD and TDD Operation in E-UTRAN 134 3.1.4.1 Reciprocity 134 3.1.4.1.1 Reciprocity of the mobile radio channel 134 3.1.4.1.2 Speed of scheduling decisions 135 3.1.4.2 UL / DL Asymmetry and Others 136 3.1.4.2.1 UL/DL symmetry 136 3.1.4.2.2 Interference scenarios 136 3.1.4.2.3 TRX architecture 137 3.1.4.2.4 Deployment in a given frequency band 137 3.1.4.3 Summary FDD vs. TDD 138 3.2 The DL Physical Channels and their Frame Structures. .140 3.2.1 Allocation of DL Physical Channels to Resource Elements 140 3.2.1.1 Not used subcarriers 142 3.2.1.2 Primary Synchronization Signal 142 3.2.1.3 Secondary Synchronization Signal 142 3.2.1.4 Pilot or Reference Signal 142 3.2.1.5 PBCH 142 3.2.1.6 PCFICH 142 3.2.1.7 PHICH 142 3.2.1.8 PDCCH 142 3.2.1.9 PDSCH (and PMCH) 142 3.2.2 System Information on PBCH and PDSCH 144 3.2.2.1 Split of the BCH on the PBCH and the PDSCH 144 3.2.3 PCFICH, PDCCH, and PHICH 146 3.2.3.1 The PCFICH 147 3.2.3.2 The PDCCH 148 3.2.3.3 The PHICH 148 3.2.4 The Downlink Processing Chain 150 3.2.4.1 Encoded transport block bits 150 3.2.4.2 Scrambling 150 3.2.4.3 Modulator 152 3.2.4.4 Layer Mapper 152 3.2.4.5 Precoding 152 3.2.4.6 OFDM signal generation 152 3.2.4.7 CP and IFFT 152 Table of Content © INACON GmbH 1999 - 2009. 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Version Number 2.030 - v - 3.3 The UL Physical Channels and their Frame Structures. .154 3.3.1 Overview UL Physical Channels (RRC_CONNECTED) 154 3.3.1.1 Scheduling Request (SR) on the PUCCH 154 3.3.1.2 Small amount of L1 information on the PUCCH 155 3.3.1.3 Big amount of L1 information on the PUSCH 155 3.3.1.4 L1 information on the PUSCH multiplexed with the TrCH data 155 3.3.1.5 Sounding reference symbols PUSCH resources 155 3.3.2 Overview PUCCH 156 3.3.3 PUCCH Mapping for ACK/NACK only and Scheduling Request 158 3.3.3.1 Usage of Zadoff-Chu sequences 158 3.3.3.2 Spreading of repeated data Zadoff-Chu symbols 160 3.3.3.3 Spreading of reference Zadoff-Chu symbols 160 3.3.3.3 PUCCH Format 1 160 3.3.3.4 PUCCH Formats 1a and 1b 160 3.3.3.5 Shortened PUCCH Formats 1a and 1b 160 3.3.3.6 Multiple access of the PUCCH 160 3.3.4 Shared usage of Resources with CAZAC Sequences 162 3.3.4.1 Zadoff-Chu sequences are CAZAC sequences 163 3.3.4.2 Separation of different UE’s with cyclic shifted Zadoff-Chu sequences 163 3.3.5.1 PUCCH Format 2 164 3.3.5.2 PUCCH Formats 2a and 2b 165 3.3.6 The Uplink Processing Chain 166 3.3.6.1 Transport block bits 166 3.3.6.2 Scrambling 166 3.3.6.3 Modulator 166 3.3.6.4 DFT pre-coder 166 3.3.6.5 Demultiplexing of signals other than data 167 3.3.6.6 Resource element mapper 167 3.3.6.7 IFFT 167 3.3.6.7 CP 167 3.4 Overview all Physical Channels 168 3.4.1 Special usage of the 6 RB around the DC carrier 169 3.4.2 Multiplexing of the PCFICH, PDCCH and the PDSCH/PMCH in the normal DL subframe 170 3.4.3 Sounding reference signal 170 3.4.4 Modulation of the physical channels 170 3.4.5 Channel coding 170 3.5 Physical Layer Procedures 172 3.5.1 Timing Advance Control 174 3.5.1.1 Principle 174 3.5.1.2 Procedure 178 3.5.1.2.1 TA while the UE is not synchronized to the eNB 178 3.5.1.2.2 TA while the UE is synchronized to the eNB 179 3.5.2 Channel Estimation DL 180 3.5.2.1 Channel Estimation Principle of LTE 180 3.5.2.1.1 The description of the mobile radio channel 180 3.5.2.1.2 Coping with a frequency selective mobile radio channel 182 3.5.2.2 Channel Estimation Downlink 184 3.5.2.2.1 Normal configuration with 4 TX antennas 184 3.5.2.2.2 Normal configuration with less than 4 TX antennas 185 LTE 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 2.030 - vi - [...]... two data streams This means that the receiver has to separate these mixed data streams from each other Since N data streams have to be separated the receiver has to receive N different versions of the N data stream signals This is why N receive antennas are needed This data separation might add quite significant effort in the receiver’s digital signal processing Since with MIMO now the data rate on a. .. create separate data streams The difference here is that not multiple carriers but multiple antennas are used in TX and RX in order to create more max throughput or signals for more users With e.g N antennas for TX and N antennas for RX (N x N) the data rate could be enhanced by N times Since each receive antenna is receiving the signals from both transmitters in the general case the mobile radio channel... only for participants of NSN LTE from A- Z Training 1 LTE from A- Z 1.2.2 Important Characteristics of LTE Physical Layer 1.2.2.1 General Physical Layer Characteristics The objectives of this section are to list the key characteristics of the physical layer and to provide understanding about how they relate to the requirements on LTE Key point of this section is that the LTE layer 1 is dominated by flexibility... 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 2.030 - 21 - Use only for participants of NSN LTE from A- Z Training 1 LTE from A- Z 1.2.3.3.3 Adaptive Antenna Systems (AAS) The objective of this section to show key features and key benefits of AAS Key point of this section is that AAS is both... wideband signal for high data rate transmission and an easy detection mechanism In the picture Orthogonality can be seen by the fact that at the position of the main lobe of each subcarriers spectrum there is a zero crossing of the other subcarriers’ spectra 1.2.3.2.4 OFDM and OFDMA Both OFDM and OFDMA are using OFDM technology The difference is: OFDMA The OFDMA transmitter is mapping signals dedicated to... German and international laws Version Number 2.030 Principles and Motivation of LTE Room for your Notes • 1 Abbreviations of this Section: 3GPP Third Generation Partnership Project (Collaboration between different standardization organizations (e.g ARIB, ETSI) to define advanced mobile communications standards, responsible for UMTS) MHz Mega Hertz (106 Hertz) 3GTR 3rd Generation Technical Report PS Packet... Version Number 2.030 -9- Use only for participants of NSN LTE from A- Z Training 1 LTE from A- Z 1.2.1.1 Support of Enhanced Quadruple Play Services Quadruple play services have not only to be followed - also the (quality) enhancements being standardized in 3GPP and the other standardization bodies have to be followed, e.g conversational QoS VoIP, fast gaming, enhanced MBMS etc For the UE Mobility speeds... prohibited and will be prosecuted to the full extent of German and international laws Version Number 2.030 - 13 - Use only for participants of NSN LTE from A- Z Training 1 LTE from A- Z 1.2.2.1.3 Smart Antenna Technology Especially MIMO Technologies and SDMA (beam forming) technology have to be mentioned here These technologies are allowing reuse of the transmission capacity of the given radio channel several... have to be interpreted from the perspective of the channel between TX and RX Therefore, a system with two RX-antennas and one TX-antenna is a SIMO Image Description • The image illustrates a system which consists of a transmitter (TX) and a receiver (RX) • Both, transmitter and receiver may deploy one or multiple antennas to send information into the channel or to receive information from that channel... E-UTRAN and its network elements look like? What key development trends are manifested in LTE? © 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 2.030 -1- Use only for participants of NSN LTE from A- Z Training 1 LTE from A- Z 1.1 Mobile Radio: Comparison . mobile access networks. To a large degree, these handsets will have at least the functionality of today’s PDA’s. Use only for participants of NSN LTE from A- Z Training LTE from A- Z 1 - 4 - © INACON. place? • What are the requirements for LTE and how do they differentiate from those of UMTS? • What are the key characteristics of LTE s (E-UTRAN’s) layer 1 and layer 2/3? • How the LTE and SAE. LTE from A- Z - Technology and Concepts of the 4G 3GPP Standard INACON GmbH Kriegsstrasse 154 76133 Karlsruhe Germany www .inacon. com e-mail: inacon@ inacon.de Cover design by Stefan Kohler ©