LTE Small Cell Optimization

Preface xiii Acknowledgements xv List of Abbreviations xvii 1 Introduction 1 Harri Holma 1.1 Introduction 1 1.2 LTE Global Deployments and Devices 2 1.3 Mobile Data Traffic Growth 3 1.4 LTE Technology Evolution 4 1.5 LTE Spectrum 5 1.6 Small Cell Deployments 6 1.7 Network Optimization 7 1.8 LTE Evolution Beyond Release 13 8 1.9 Summary 9 References 9 2 LTE and LTE Advanced in Releases 8–11 11 Antti Toskala 2.1 Introduction 11 2.2 Releases 8 and 9 LTE 11 2.2.1 Releases 8 and 9 Physical Layer 12 2.2.2 LTE Architecture 17 2.2.3 LTE Radio Protocols 17 2.3 LTE Advanced in Releases 10 and 11 19 2.3.1 Carrier Aggregation 19 2.3.2 Multiple Input Multiple Output Enhancements 23 2.3.3 HetNet Enhanced Inter-cell Interference Coordination 23 2.3.4 Coordinated Multipoint Transmission 25 2.4 UE Capability in Releases 8–11 26 2.5 Conclusions 28 References 28 3 LTE-Advanced Evolution in Releases 12–13 29 Antti Toskala 3.1 Introduction 29 3.2 Machine-Type Communications 29 3.3 Enhanced CoMP 34 3.4 FDD–TDD Carrier Aggregation 35 3.5 WLAN-Radio Interworking 37 3.6 Device-to-Device Communication with LTE 39 3.7 Single Cell Point to Multipoint Transmission 41 3.8 Release 12 UE Capabilities 42 3.9 Conclusions 42 References 43 4 Small Cell Enhancements in Release 12/13 45 Antti Toskala, Timo Lunttila, Tero Henttonen and Jari Lindholm 4.1 Introduction 45 4.2 Small Cell and Dual Connectivity Principles 45 4.3 Dual Connectivity Architecture Principle 46 4.4 Dual Connectivity Protocol Impacts 47 4.5 Dual Connectivity Physical Layer Impacts and Radio Link Monitoring 49 4.6 Other Small Cell Physical Layer Enhancement 53 4.6.1 256QAM for LTE Downlink 53 4.6.2 Small Cell ON/OFF Switching and Enhanced Discovery 53 4.6.3 Power Saving with Small Cell ON/OFF 56 4.6.4 Over the Air Synchronization Between eNodeBs 56 4.7 Release 13 Enhancements 56 4.8 Conclusions 57 References 57 5 Small Cell Deployment Options 59 Harri Holma and Benny Vejlgaard 5.1 Introduction 59 5.2 Small Cell Motivation 60 5.3 Network Architecture Options 60 5.4 Frequency Usage 64 5.5 Selection of Small Cell Location 65 5.6 Indoor Small Cells 67 5.6.1 Distributed Antenna Systems 67 5.6.2 Wi-Fi and Femto Cells 68 5.6.3 Femto Cell Architecture 70 5.6.4 Recommendations 72 5.7 Cost Aspects 72 5.7.1 Macro Network Extension 73 5.7.2 Outdoor Small Cells 73 5.7.3 Outdoor Pico Cluster 73 5.7.4 Indoor Offloading 74 5.8 Summary 74 References 75 6 Small Cell Products 77 Harri Holma and Mikko Simanainen 6.1 Introduction 77 6.2 3GPP Base Station Categories 78 6.3 Micro Base Stations 78 6.4 Pico Base Stations 80 6.5 Femtocells 83 6.6 Low-Power Remote Radio Heads 84 6.6.1 Alternative Remote Radio Head Designs for Indoor Use 86 6.7 Distributed Antenna Systems 87 6.8 Wi-Fi Integration 87 6.9 Wireless Backhaul Products 89 6.10 Summary 90 Reference 90 7 Small Cell Interference Management 91 Rajeev Agrawal, Anand Bedekar, Harri Holma, Suresh Kalyanasundaram, Klaus Pedersen and Beatriz Soret 7.1 Introduction 91 7.2 Packet Scheduling Solutions 93 7.3 Enhanced Inter-cell Interference Coordination 97 7.3.1 Concept Description 97 7.3.2 Performance and Algorithms 101 7.4 Enhanced Coordinated Multipoint (eCoMP) 110 7.5 Coordinated Multipoint (CoMP) 114 7.6 Summary 119 References 120 8 Small Cell Optimization 121 Harri Holma, Klaus Pedersen, Claudio Rosa, Anand Bedekar and Hua Wang 8.1 Introduction 121 8.2 HetNet Mobility Optimization 122 8.3 Inter-site Carrier Aggregation with Dual Connectivity 126 8.3.1 User Data Rates with Inter-site Carrier Aggregation 126 8.3.2 Mobility with Dual Connectivity 131 8.4 Ultra Dense Network Interference Management 135 8.4.1 Ultra Dense Network Characteristics 135 8.4.2 Proactive Time-Domain Inter-cell Interference Coordination 136 8.4.3 Reactive Carrier-Based Inter-cell Interference Coordination 138 8.5 Power Saving with Small Cell On/Off 139 8.6 Multivendor Macro Cell and Small Cells 141 8.7 Summary 143 References 143 9 Learnings from Small Cell Deployments 145 Brian Olsen and Harri Holma 9.1 Introduction 145 9.2 Small Cell Motivations by Mobile Operators 145 9.3 Small Cell Challenges and Solutions 146 9.4 Summary of Learnings from Small Cell Deployments 147 9.5 Installation Considerations 151 9.6 Example Small Cell Case Study 152 9.6.1 Site Solution and Backhaul 152 9.6.2 Coverage and User Data Rates 153 9.6.3 Macro Cell Offloading and Capacity 154 9.6.4 KPIs in Network Statistics 155 9.6.5 Mobility Performance 156 9.6.6 Parameter and RF Optimization 157 9.7 Summary 158 10 LTE Unlicensed 159 Antti Toskala and Harri Holma 10.1 Introduction 159 10.2 Unlicensed Spectrum 160 10.3 Operation Environment 161 10.4 Motivation for the Use of Unlicensed Spectrum with LTE 162 10.5 Key Requirements for 5 GHz Band Coexistence 162 10.6 LTE Principle on Unlicensed Band 164 10.7 LTE Performance on the Unlicensed Band 165 10.8 Coexistence Performance 166 10.9 Coverage with LTE in 5 GHz Band 170 10.10 Standardization 172 10.11 Conclusions 172 References 173 11 LTE Macro Cell Evolution 175 Mihai Enescu, Amitava Ghosh, Bishwarup Mondal and Antti Toskala 11.1 Introduction 175 11.2 Network-Assisted Interference Cancellation 176 11.3 Evolution of Antenna Array Technology 181 11.4 Deployment Scenarios for Antenna Arrays 182 11.5 Massive-MIMO Supported by LTE 187 11.5.1 Sectorization (Vertical)-Based Approaches 187 11.5.2 Reciprocity-Based Approaches 188 11.6 Further LTE Multi-antenna Standardization 189 11.7 Release 13 Advanced Receiver Enhancements 192 11.8 Conclusions 192 References 193 12 LTE Key Performance Indicator Optimization 195 Jussi Reunanen, Jari Salo and Riku Luostari 12.1 Introduction 195 12.2 Key Performance Indicators 196 12.3 Physical Layer Optimization 197 12.4 Call Setup 200 12.4.1 Random Access Setup 202 12.4.2 RRC Connection Setup 208 12.4.3 E-RAB Setup 215 12.5 E-RAB Drop 218 12.5.1 Handover Performance 218 12.5.2 UE-Triggered RRC Connection Re-establishments 222 12.5.3 eNodeB-triggered RRC Connection Re-establishments 226 12.6 Handover and Mobility Optimization 228 12.7 Throughput Optimization 232 12.7.1 MIMO Multi-stream Usage Optimization 234 12.8 High-Speed Train Optimization 243 12.9 Network Density Benchmarking 246 12.10 Summary 247 References 248 13 Capacity Optimization 249 Jussi Reunanen, Riku Luostari and Harri Holma 13.1 Introduction 249 13.2 Traffic Profiles in Mass Events 251 13.3 Uplink Interference Management 255 13.3.1 PUSCH 257 13.3.2 PUCCH 265 13.3.3 RACH and RRC Setup Success Rate 265 13.3.4 Centralized RAN 269 13.4 Downlink Interference Management 270 13.4.1 PDSCH 271 13.4.2 Physical Downlink Control Channel 276 13.5 Signalling Load and Number of Connected Users Dimensioning 279 13.5.1 Signalling Load 280 13.5.2 RRC-Connected Users 280 13.6 Load Balancing 284 13.7 Capacity Bottleneck Analysis 286 13.8 Summary 291 References 292 14 VoLTE Optimization 293 Riku Luostari, Jari Salo, Jussi Reunanen and Harri Holma 14.1 Introduction 293 14.2 Voice Options for LTE Smartphones 293 14.3 Circuit Switched Fallback 294 14.3.1 Basic Concepts 294 14.3.2 CSFB Call Setup Time, Transition to Target RAT 296 14.3.3 CSFB Call Setup Success Rate 302 14.3.4 Return to LTE after CSFB Call 302 14.4 Voice over LTE 307 14.4.1 Setup Success Rate and Drop Rate 307 14.4.2 TTI Bundling and RLC Segmentation 310 14.4.3 Semi-persistent Scheduling 312 14.4.4 Packet Bundling 314 14.4.5 Re-establishment with Radio Preparations 315 14.4.6 Voice Quality on VoLTE 315 14.5 Single Radio Voice Call Continuity 322 14.5.1 Signalling Flows 322 14.5.2 Performance 326 14.6 Summary 331 References 331 15 Inter-layer Mobility Optimization 333 Jari Salo and Jussi Reunanen 15.1 Introduction 333 15.2 Inter-layer Idle Mode Mobility and Measurements 334 15.2.1 Initial Cell Selection and Minimum Criteria for UE to Camp on a Cell 334 15.2.2 Summary of Cell Reselection Rules 336 15.2.3 Idle Mode Measurements 338 15.3 Inter-layer Connected Mode Measurements 344 15.4 Inter-layer Mobility for Coverage-Limited Network 350 15.4.1 Basic Concepts 350 15.4.2 Mapping Throughput Target to SINR, RSRQ and RSRP 353 15.4.3 Inter-layer Mobility Example #1 (Non-equal Priority Non-equal Bandwidth LTE Layers) 361 15.4.4 Inter-layer Mobility Example #2 (Equal Priority Equal Bandwidth LTE Layers) 368 15.5 Inter-layer Mobility for Capacity-Limited Networks 370 15.5.1 Static Load Balancing via Mobility Thresholds 371 15.5.2 Dynamic Load Balancing via eNodeB Algorithms 375 15.6 Summary 377 References 377 16 Smartphone Optimization 379 Rafael Sanchez-Mejias, Laurent No¨el and Harri Holma 16.1 Introduction 379 16.2 Smartphone Traffic Analysis in LTE Networks 380 16.2.1 Data Volumes and Asymmetry 380 16.2.2 Traffic-Related Signalling 381 16.2.3 Mobility-Related Signalling 382 16.2.4 User Connectivity 382 16.3 Smartphone Power Consumption Optimization 384 16.3.1 Impact of Downlink Carrier Aggregation 384 16.3.2 Impact of Discontinuous Reception 385 16.4 Smartphone Operating Systems 391 16.5 Messaging Applications 391 16.6 Streaming Applications 393 16.7 Voice over LTE 394 16.7.1 VoLTE System Architecture 395 16.7.2 VoLTE Performance Analysis 396 16.7.3 Standby Performance 404 16.7.4 Impact of Network Loading and Radio Quality 405 16.8 Smartphone Battery, Baseband and RF Design Aspects 406 16.8.1 Trends in Battery Capacity 406 16.8.2 Trends in Cellular Chipset Power Consumption 409 16.8.3 Impact of Small Cells on Smartphone Power Consumption 412 16.9 Summary 421 References 421 17 Further Outlook for LTE Evolution and 5G 423 Antti Toskala and Karri Ranta-aho 17.1 Introduction 423 17.2 Further LTE-Advanced Beyond Release 13 423 17.3 Towards 5G 426 17.4 5G Spectrum 427 17.5 Key 5G Radio Technologies 428 17.6 Expected 5G Schedule 430 17.7 Conclusions 432 References 432 Index 433