An Introduction to LTE

Christopher Cox is a professional technical trainer and consultant in mobile telecommunications. He is an expert in the technical and radio network planning aspects of LTE and UMTS, and regularly delivers training courses about them to audiences drawn from equipment manufacturers, network operators and consultancies worldwide. 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 xxi Acknowledgements xxiii List of Abbreviations xxv 1 Introduction 1 1.1 Architectural Review of UMTS and GSM 1 1.1.1 High-Level Architecture 1 1.1.2 Architecture of the Radio Access Network 2 1.1.3 Architecture of the Core Network 4 1.1.4 Communication Protocols 5 1.2 History of Mobile Telecommunication Systems 6 1.2.1 From 1G to 3G 6 1.2.2 Third Generation Systems 7 1.3 The Need for LTE 8 1.3.1 The Growth of Mobile Data 8 1.3.2 Capacity of a Mobile Telecommunication System 9 1.3.3 Increasing the System Capacity 10 1.3.4 Additional Motivations 11 1.4 From UMTS to LTE 11 1.4.1 High-Level Architecture of LTE 11 1.4.2 Long-Term Evolution 12 1.4.3 System Architecture Evolution 13 1.4.4 LTE Voice Calls 14 1.4.5 The Growth of LTE 15 1.5 From LTE to LTE-Advanced 16 1.5.1 The ITU Requirements for 4G 16 1.5.2 Requirements of LTE-Advanced 16 1.5.3 4G Communication Systems 16 1.5.4 The Meaning of 4G 17 1.6 The 3GPP Specifications for LTE 17 References 19 2 System Architecture Evolution 21 2.1 High-Level Architecture of LTE 21 2.2 User Equipment 21 2.2.1 Architecture of the UE 21 2.2.2 UE Capabilities 22 2.3 Evolved UMTS Terrestrial Radio Access Network 23 2.3.1 Architecture of the E-UTRAN 23 2.3.2 Transport Network 24 2.3.3 Small Cells and the Home eNB 25 2.4 Evolved Packet Core 25 2.4.1 Architecture of the EPC 25 2.4.2 Roaming Architecture 27 2.4.3 Network Areas 28 2.4.4 Numbering, Addressing and Identification 28 2.5 Communication Protocols 30 2.5.1 Protocol Model 30 2.5.2 Air Interface Transport Protocols 31 2.5.3 Fixed Network Transport Protocols 31 2.5.4 User Plane Protocols 32 2.5.5 Signalling Protocols 33 2.6 Example Signalling Flows 34 2.6.1 Access Stratum Signalling 34 2.6.2 Non-Access Stratum Signalling 35 2.7 Bearer Management 36 2.7.1 The EPS Bearer 36 2.7.2 Default and Dedicated Bearers 37 2.7.3 Bearer Implementation Using GTP 38 2.7.4 Bearer Implementation Using GRE and PMIP 39 2.7.5 Signalling Radio Bearers 39 2.8 State Diagrams 40 2.8.1 EPS Mobility Management 40 2.8.2 EPS Connection Management 40 2.8.3 Radio Resource Control 41 2.9 Spectrum Allocation 43 References 45 3 Digital Wireless Communications 49 3.1 Radio Transmission and Reception 49 3.1.1 Carrier Signal 49 3.1.2 Modulation Techniques 50 3.1.3 The Modulation Process 51 3.1.4 The Demodulation Process 53 3.1.5 Channel Estimation 55 3.1.6 Bandwidth of the Modulated Signal 55 3.2 Radio Transmission in a Mobile Cellular Network 56 3.2.1 Multiple Access Techniques 56 3.2.2 FDD and TDD Modes 56 3.3 Impairments to the Received Signal 58 3.3.1 Propagation Loss 58 3.3.2 Noise and Interference 58 3.3.3 Multipath and Fading 58 3.3.4 Inter-symbol Interference 60 3.4 Error Management 61 3.4.1 Forward Error Correction 61 3.4.2 Automatic Repeat Request 62 3.4.3 Hybrid ARQ 63 References 65 4 Orthogonal Frequency Division Multiple Access 67 4.1 Principles of OFDMA 67 4.1.1 Sub-carriers 67 4.1.2 The OFDM Transmitter 68 4.1.3 The OFDM Receiver 70 4.1.4 The Fast Fourier Transform 72 4.1.5 Block Diagram of OFDMA 72 4.1.6 Details of the Fourier Transform 73 4.2 Benefits and Additional Features of OFDMA 75 4.2.1 Orthogonal Sub-carriers 75 4.2.2 Choice of Sub-carrier Spacing 75 4.2.3 Frequency-Specific Scheduling 77 4.2.4 Reduction of Inter-symbol Interference 78 4.2.5 Cyclic Prefix Insertion 79 4.2.6 Choice of Symbol Duration 80 4.2.7 Fractional Frequency Re-use 81 4.3 Single Carrier Frequency Division Multiple Access 82 4.3.1 Power Variations From OFDMA 82 4.3.2 Block Diagram of SC-FDMA 83 References 85 5 Multiple Antenna Techniques 87 5.1 Diversity Processing 87 5.1.1 Receive Diversity 87 5.1.2 Closed Loop Transmit Diversity 88 5.1.3 Open Loop Transmit Diversity 89 5.2 Spatial Multiplexing 90 5.2.1 Principles of Operation 90 5.2.2 Open Loop Spatial Mult