An Introduction to LTE

Christopher Cox is a professional technical trainer and consultant in mobile telecommunications. He has a degree in Physics and a PhD in Radio Astronomy from the University of Cambridge, and 20 years' experience in scientific and technical consultancy, telecommunications and training.

Preface Acknowledgements List of Abbreviations 1 Introduction 1.1 Architectural Review of UMTS and GSM 1.1.1 High Level Architecture 1.1.2 Architecture of the Radio Access Network 1.1.3 Architecture of the Core Network 1.1.4 Communication Protocols 1.2 History of Mobile Telecommunication Systems 1.2.1 From 1G to 3G 1.2.2 Third Generation Systems 1.3 The Need for LTE 1.3.1 The Growth of Mobile Data 1.3.2 Capacity of a Mobile Telecommunication System 1.3.3 Increasing the System Capacity 1.3.4 Additional Motivations 1.4 From UMTS to LTE 1.4.1 High Level Architecture of LTE 1.4.2 Long Term Evolution 1.4.3 System Architecture Evolution 1.5 From LTE to LTE-Advanced 1.5.1 The ITU Requirements for 4G 1.5.2 Requirements of LTE-Advanced 1.5.3 4G Communication Systems 1.5.4 The Meaning of 4G 1.6 The 3GPP Specifications for LTE References 2 System Architecture Evolution 2.1 Architecture of LTE 2.1.1 High Level Architecture 2.1.2 User Equipment 2.1.3 Evolved UMTS Terrestrial Radio Access Network 2.1.4 Evolved Packet Core 2.1.5 Roaming Architecture 2.1.6 Network Areas 2.1.7 Numbering, Addressing and Identification 2.2 Communication Protocols 2.2.1 Protocol Model 2.2.2 Air Interface Transport Protocols 2.2.3 Fixed Network Transport Protocols 2.2.4 User Plane Protocols 2.2.5 Signalling Protocols 2.3 Example Information Flows 2.3.1 Access Stratum Signalling 2.3.2 Non Access Stratum Signalling 2.3.3 Data Transport 2.4 Bearer Management 2.4.1 The EPS Bearer 2.4.2 Tunnelling Using GTP 2.4.3 Tunnelling Using GRE and PMIP 2.4.4 Signalling Radio Bearers 2.5 State Diagrams 2.5.1 EPS Mobility Management 2.5.2 EPS Connection Management 2.5.3 Radio Resource Control 2.6 Spectrum Allocation References 3 Digital Wireless Communications 3.1 Radio Transmission and Reception 3.1.1 Signal Transmission 3.1.2 Signal Reception 3.1.3 Channel Estimation 3.1.4 Multiple Access Techniques 3.1.5 FDD and TDD Modes 3.2 Multipath, Fading and Inter-Symbol Interference 3.2.1 Multipath and Fading 3.2.2 Inter-Symbol Interference 3.3 Error Management 3.3.1 Forward Error Correction 3.3.2 Automatic Repeat Request 3.3.3 Hybrid ARQ References 4 Orthogonal Frequency Division Multiple Access 4.1 Orthogonal Frequency Division Multiplexing 4.1.1 Reduction of Inter-Symbol Interference using OFDM 4.1.2 The OFDM Transmitter 4.1.3 Initial Block Diagram 65 4.2 OFDMA in a Mobile Cellular Network 4.2.1 Multiple Access 4.2.2 Fractional Frequency Re-Use 4.2.3 Channel Estimation 4.2.4 Cyclic Prefix Insertion 4.2.5 Use of the Frequency Domain 4.2.6 Choice of Sub-Carrier Spacing 4.3 Single Carrier Frequency Division Multiple Access 4.3.1 Power Variations from OFDMA 4.3.2 Block Diagram of SC-FDMA References 5 Multiple Antenna Techniques 5.1 Diversity Processing 5.1.1 Receive Diversity 5.1.2 Closed Loop Transmit Diversity 5.1.3 Open Loop Transmit Diversity 5.2 Spatial Multiplexing 5.2.1 Principles of Operation 5.2.2 Open Loop Spatial Multiplexing 5.2.3 Closed Loop Spatial Multiplexing 5.2.4 Matrix Representation 5.2.5 Implementation Issues 5.2.6 Multiple User MIMO 5.3 Beamforming 5.3.1 Principles of Operation 5.3.2 Beam Steering 5.3.3 Dual Layer Beamforming 5.3.4 Downlink Multiple User MIMO Revisited References 6 Architecture of the LTE Air Interface 6.1 Air Interface Protocol Stack 6.2 Logical, Transport and Physical Channels 6.2.1 Logical Channels 6.2.2 Transport Channels 6.2.3 Physical Data Channels 6.2.4 Control Information 6.2.5 Physical Control Channels 6.2.6 Physical Signals 6.2.7 Information Flows 6.3 The Resource Grid 6.3.1 Slot Structure 6.3.2 Frame Structure 6.3.3 Uplink Timing Advance 6.3.4 Resource Grid Structure 6.3.5 Bandwidth Options 6.4 Multiple Antenna Transmission 6.4.1 Downlink Antenna Ports 6.4.2 Downlink Transmission Modes 6.5 Resource Element Mapping 6.5.1 Downlink Resource Element Mapping 6.5.2 Uplink Resource Element Mapping References 7 Cell Acquisition 7.1 Acquisition Procedure 7.2 Synchronization Signals 7.2.1 Physical Cell Identity 7.2.2 Primary Synchronization Signal 7.2.3 Secondary Synchronization Signal 7.3 Downlink Reference Signals 7.4 Physical Broadcast Channel 7.5 Physical Control Format Indicator Channel 7.6 System Information 7.6.1 Organization of the System Information 7.6.2 Transmission and Reception of the System Information 7.7 Procedures After Acquisition References 8 Data Transmission and Reception 8.1 Data Transmission Procedures 8.1.1 Downlink Transmission and Reception 8.1.2 Uplink Transmission and Reception 8.1.3 Semi Persistent Scheduling 8.2 Transmission of Scheduling Messages on the PDCCH 8.2.1 Downlink Control Information 8.2.2 Resource Allocation 8.2.3 Example: DCI Format 1 8.2.4 Radio Network Temporary Identifiers 8.2.5 Transmission and Reception of the PDCCH 8.3 Data Transmission on the PDSCH and PUSCH 8.3.1 Transport Channel Processing 8.3.2 Physical Channel Processing 8.4 Transmission of Hybrid ARQ Indicators on the PHICH 8.4.1 Introduction 8.4.2 Resource Element Mapping of the PHICH 8.4.3 Physical Channel Processing of the PHICH 8.5 Uplink Control Information 8.5.1 Hybrid ARQ Acknowledgements 8.5.2 Channel Quality Indicator 8.5.3 Rank Indication 8.5.4 Precoding Matrix Indicator 8.5.5 Channel State Reporting Mechanisms 8.5.6 Scheduling Requests 8.6 Transmission of Uplink Control Information on the PUCCH 8.6.1 PUCCH Formats 8.6.2 PUCCH Resources 8.6.3 Physical Channel Processing of the PUCCH 8.7 Uplink Reference Signals 8.7.1 Demodulation Reference Signal 8.7.2 Sounding Reference Signal 8.8 Uplink Power Control 8.8.1 Uplink Power Calculation 8.8.2 Uplink Power Control Commands 8.9 Discontinuous Reception 8.9.1 Discontinuous Reception and Paging in RRC-IDLE 8.9.2 Discontinuous Reception in RRC-CONNECTED References 9 Random Access 9.1 Transmission of Random Access Preambles on the PRACH 9.1.1 Resource Element Mapping 9.1.2 Preamble Sequence Generation 9.1.3 Signal Transmission 9.2 Non Contention Based Procedure 9.3 Contention Based Procedure References 10 Air Interface Layer 2 10.1 Medium Access Control Protocol 10.1.1 Protocol Architecture 10.1.2 Timing Advance Commands 10.1.3 Buffer Status Reporting 10.1.4 Power Headroom Reporting 10.1.5 Multiplexing and De-Multiplexing 10.1.6 Logical Channel Prioritization 10.1.7 Scheduling of Transmissions on the Air Interface 10.2 Radio Link Control Protocol 10.2.1 Protocol Architecture 10.2.2 Transparent Mode 10.2.3 Unacknowledged Mode 10.2.4 Acknowledged Mode 10.3 Packet Data Convergence Protocol 10.3.1 Protocol Architecture 10.3.2 Header Compression 10.3.3 Prevention of Packet Loss during Handover References 11 Power-On and Power-Off Procedures 11.1 Power-On Sequence 11.2 Network and Cell Selection 11.2.1 Network Selection 11.2.2 Closed Subscriber Group Selection 11.2.3 Cell Selection 11.3 RRC Connection Establishment 11.3.1 Basic Procedure 11.3.2 Relationship with Other Procedures 11.4 Attach Procedure 11.4.1 IP Address Allocation 11.4.2 Overview of the Attach Procedure 11.4.3 Attach Request 11.4.4 Identification and Security Procedures 11.4.5 Location Update 11.4.6 Default Bearer Creation 11.4.7 Attach Accept 11.4.8 Default Bearer Update 11.5 Detach Procedure References 12 Security Procedures 12.1 Network Access Security 12.1.1 Security Architecture 12.1.2 Key Hierarchy 12.1.3 Authentication and Key Agreement 12.1.4 Security Activation 12.1.5 Ciphering 12.1.6 Integrity Protection 12.2 Network Domain Security 12.2.1 Security Protocols 12.2.2 Security in the Evolved Packet Core 12.2.3 Security in the Radio Access Network References 13 Quality of Service, Policy and Charging 13.1 Policy and Charging Control 13.1.1 Introduction 13.1.2 Quality of Service Parameters 13.1.3 Policy Control Architecture 13.2 Session Management Procedures 13.2.1 IP-CAN Session Establishment 13.2.2 Mobile Originated QoS Request 13.2.3 Server Originated QoS Request 13.2.4 Dedicated Bearer Establishment 13.2.5 Other Session Management Procedures 13.3 Charging and Billing 13.3.1 High Level Architecture 13.3.2 Offline Charging 13.3.3 Online Charging References 14 Mobility Management 14.1 Transitions between Mobility Management States 14.1.1 S1 Release Procedure 14.1.2 Paging Procedure 14.1.3 Service Request Procedure 14.2 Cell Reselection in RRC-IDLE 14.2.1 Objectives 14.2.2 Cell Reselection on the Same LTE Frequency 14.2.3 Cell Reselection to a Different LTE Frequency 14.2.4 Fast Moving Mobiles 14.2.5 Tracking Area Update Procedure 14.2.6 Network Reselection 14.3 Measurements in RRC-CONNECTED 14.3.1 Objectives 14.3.2 Measurement Procedure 14.3.3 Measurement Reporting 14.3.4 Measurement Gaps 14.4 Handover in RRC-CONNECTED 14.4.1 X2 Based Handover Procedure 14.4.2 Handover Variations References 15 Inter-System Operation 15.1 Inter-Operation with UMTS and GSM 15.1.1 S3-Based Architecture 15.1.2 Gn/Gp-Based Architecture 15.1.3 Bearer Management 15.1.4 Power-On Procedures 15.1.5 Cell Reselection in RRC-IDLE 15.1.6 Idle Mode Signalling Reduction 15.1.7 Measurements in RRC-CONNECTED 15.1.8 Handover in RRC-CONNECTED 15.2 Inter-Operation with Generic Non 3GPP Technologies 15.2.1 Network Based Mobility Architecture 15.2.2 Host Based Mobility Architecture 241 15.2.3 Attach Procedure 15.2.4 Cell Reselection and Handover 15.3 Inter-Operation with cdma2000 HRPD 15.3.1 System Architecture 15.3.2 Preregistration with cdma2000 15.3.3 Cell Reselection in RRC-IDLE 15.3.4 Measurements and Handover in RRC-CONNECTED References 16 Delivery of Voice and Text Messages over LTE 16.1 The Market for Voice and SMS 16.2 Third Party Voice over IP 16.3 The IP Multimedia Subsystem 16.3.1 IMS Architecture 16.3.2 IMS Procedures 16.3.3 SMS over the IMS 16.4 Circuit Switched Fallback 16.4.1 Architecture 16.4.2 Combined EPS/IMSI Attach Procedure 16.4.3 Voice Call Setup 16.4.4 SMS over SGs 16.4.5 Circuit Switched Fallback to cdma2000 1xRTT 16.5 VoLGA References 17 Enhancements in Release 9 17.1 Multimedia Broadcast/Multicast Service 17.1.1 Introduction 17.1.2 Multicast/Broadcast over a Single Frequency Network 17.1.3 Implementation of MBSFN in LTE 17.1.4 Architecture of MBMS 17.1.5 Operation of MBMS 17.2 Location Services 17.2.1 Introduction 17.2.2 Positioning Techniques 17.2.3 Location Service Architecture 17.2.4 Location Service Procedures 17.3 Other Enhancements in Release 9 17.3.1 Dual Layer Beamforming 17.3.2 Commercial Mobile Alert System 17.3.3 Enhancements to Earlier Features of LTE References 18 LTE-Advanced and Release 10 18.1 Carrier Aggregation 18.1.1 Principles of Operation 18.1.2 UE Capabilities 18.1.3 Scheduling 18.1.4 Data Transmission and Reception 18.1.5 Uplink and Downlink Feedback 18.1.6 Other Physical Layer and MAC Procedures 18.1.7 RRC Procedures 18.2 Enhanced Downlink MIMO 18.2.1 Objectives 18.2.2 Downlink Reference Signals 18.2.3 Downlink Transmission and Feedback 18.3 Enhanced Uplink MIMO 18.3.1 Objectives 18.3.2 Implementation 18.4 Relays 18.4.1 Principles of Operation 18.4.2 Relaying Architecture 18.4.3 Enhancements to the Air Interface 18.5 Release 11 and Beyond 18.5.1 Coordinated Multipoint Transmission and Reception 18.5.2 Enhanced Carrier Aggregation References 19 Self Optimizing Networks 19.1 Self Optimizing Networks in Release 8 19.1.1 Self Configuration of an eNB 19.1.2 Automatic Neighbour Relations 19.1.3 Interference Coordination 19.1.4 Mobility Load Balancing 19.2 New Features in Release 9 19.2.1 Mobility Robustness Optimization 19.2.2 Random Access Channel Optimization 19.2.3 Energy Saving 20 Performance of LTE and LTE-Advanced 20.1 Coverage Estimation 20.2 Peak Data Rates of LTE and LTE-Advanced 20.2.1 Increase of the Peak Data Rate 20.2.2 Limitations on the Peak Data Rate 20.3 Typical Data Rates of LTE and LTE-Advanced 20.3.1 Total Cell Capacity 20.3.2 Data Rate at the Cell Edge References Bibliography Index