LTE Self-Organising Networks (SON) Network Management Automation for Operational Efficiency

Seppo Hämäläinen is research manager at Nokia Siemens Networks. He received an MSc degree in Electrical Engineering from the Department of Information Technology at Lappeenranta University of Technology in 1994 and a PhD degree in Electrical Engineering from the Department of Information technology at Jyväskylä University in 2003. He joined Nokia Research Center in 1993, where he worked in various research and research management positions until the end of 2005. From 2002 to 2005 he led Nokia Research Center’s office in China and at the beginning of 2006 he joined Nokia Networks, where he was director of Network Systems Research. He is now working with Nokia Siemens Networks. His research interests cover 3G and beyond 3G radio network performance and radio resource management issues and self-organizing networks. He is author or co-author of 50 scientific journal and conference papers and book chapters, and 18 independent patents.

Henning Sanneck

Dr. Henning Sanneck studied Electrical Engineering at the University of Erlangen-Nuremberg, Germany. After receiving his Diploma in 1995, he joined GMD Fokus (now part of Fraunhofer) in Berlin. At Fokus, he worked as a Researcher in the area of Quality-of-Service (QoS) support for Real-Time Services in IP-based networks. He received his Dr.-Ing. (PhD) degree in Electrical Engineering from the Technical University of Berlin with a thesis on Voice over IP QoS in 2000. In 2001 he joined Siemens - Mobile Networks in Munich, working as a Senior Research Engineer on cross-layer design for IP-based Radio Access Networks (RANs), Software Technologies for Mobile Networks and Technology Management. He became a Project Manager for technology innovation projects in the area of Network Management for 3G and beyond RANs in 2003, working on Basestation Auto-Configuration and Real-Time Performance Management concepts and their realisation as product features. Since the formation of Nokia Siemens Networks in 2007 he has been a Research Manager heading the "Network Management Automation" team. Dr. Sanneck has published 40 papers in refereed conferences and journals and has more than 15 patents granted or pending.

Cinzia Sartori

Cinzia Sartori is Research Area Manager at Nokia Siemens Networks. After graduating in Electronic Engineer at the University of Pavia in Italy, she was based at GTE in SW Research & Development and transferred for 18 months to Phoenix (Arizona, USA). In the early 1990s she joined Siemens - Mobile Networks R&D- for the development of the “BSC–Base Station Controller” leading a SW team for SS7 and Radio Resource Management development; later she moved to “RAN System Engineering and Tests”. At the establishment of Nokia Siemens Networks in 2007, she lead the Network Telecom team in RAN System Architecture, dealing with 2G, 3G, WiMax and LTE call processing. Since November 2009 she has worked at the Radio Research unit of Nokia Siemens Networks and is responsible for the Self Organizing Networks (SON) research field. She participated in 3GPP standardization in SA2 working group and currently she leads the Nokia- NSN team responsible for defining the SON strategy in 3GPP RAN standardization.

Preface xv

List of Contributors xix

Acknowledgements xxi

List of Abbreviations xxiii

1. Introduction 1

1.1 Self-Organising Networks (SON) 3

1.2 The Transition from Conventional Network Operation to SON 6

1.2.1 Automation of the Network Rollout 9

1.2.2 Automation of Network Optimisation and Troubleshooting 10

1.2.3 SON Characteristics and Challenges 11

References 12

2. LTE Overview 13

2.1 Introduction to LTE and SAE 13

2.1.1 3GPP Structure, Timeline and LTE Specifications 14

2.1.2 LTE Requirements 16

2.1.3 System Architecture Overview 16

2.1.4 Evolved UTRAN 18

2.1.5 E-UTRAN Functional Elements 19

2.1.6 Evolved Packet Core 21

2.1.7 Voice over LTE (VoLTE) 24

2.1.8 LTE-Advanced 24

2.1.9 Network Management 30

2.2 LTE Radio Access Network Scenarios and Their Evolution 33

2.2.1 LTE Radio Coverage Scenario 33

2.2.2 LTE for Capacity Enhancement in Existing GERAN/UTRAN 34

2.2.3 Enhancing LTE Capacity, the Multi-Layer LTE 34

2.2.4 Data Offloading, LIPA-SIPTO 35

2.2.5 Multi-Radio Access Network Scenarios or non-GPP 36

References 37

3. Self-Organising Networks (SON) 39

3.1 Vision 39

3.2 NGMN Operator Use Cases and 3GPP SON Use Cases 42

3.2.1 Operational Use Cases 42

3.2.2 NGMN SON Use Cases and Requirements 47

3.2.3 SON Use Cases in 3GPP 50

3.3 Foundations for SON 52

3.3.1 Control Engineering: Feedback Loops 53

3.3.2 Autonomic Computing and Autonomic Management 55

3.3.3 SON Research Projects 57

3.4 Architecture 60

3.4.1 Use-Case Related Criteria 62

3.4.2 System-Level Criteria 64

3.5 Business Value 65

3.5.1 The Economics of eNB Sites 65

3.5.2 General Mode of Operation of SON 68

3.5.3 Installation and Planning 71

3.5.4 Network Optimisation 72

3.5.5 Fault Management 73

3.5.6 Conclusions 74

3.6 SON Operational and Technical Challenges 75

3.6.1 Transition of Operational Processes to SON 75

3.6.2 Technical (Engineering) Challenges 78

References 80

4. Self-Configuration (‘Plug-and-Play’) 81

4.1 Auto-Connectivity and -Commissioning 82

4.1.1 Preparation 85

4.1.2 Connectivity Setup, Site-Identification and Auto-Commissioning 87

4.1.3 LTE-A Relay Auto-Connectivity 93

4.1.4 Conclusions 100

4.2 Dynamic Radio Configuration 100

4.2.1 Generation of Initial Transmission Parameters 106

4.2.2 Physical Cell-ID Allocation 111

4.2.3 Automatic Neighbour Relationship Setup (ANR) 118

4.2.4 DRC Architecture 130

4.2.5 Conclusions 132

References 133

5. Self-Optimisation 135

5.1 Mobility Robustness Optimisation 136

5.1.1 Goals of MRO 136

5.1.2 Cell Changes and Interference Challenges 137

5.1.3 MRO Relevant Parameters 140

5.1.4 Causes for Mobility Problems 144

5.1.5 MRO Solutions 146

5.1.6 MRO Time Scales 151

5.1.7 MRO Performance 152

5.2 Mobility Load Balancing and Traffic Steering 157

5.2.1 Introduction to Traffic Steering 157

5.2.2 SON Policies for Mobility Load Balancing 159

5.2.3 A Theoretical View of Load Balancing 160

5.2.4 Standardised Features and Procedures to Direct UEs to the Desired Layer 166

5.2.5 Exemplary Results of MLB 182

5.2.6 Uplink Load Balancing 189

5.2.7 Interactions Between TS/MLB and MRO 190

5.3 Energy Saving 193

5.3.1 Introduction 193

5.3.2 Requirements 195

5.3.3 Energy Saving Management 195

5.3.4 eNB Overlaid Scenario 196

5.3.5 Capacity-Limited Network 198

5.3.6 Equipment/Local ES 200

5.3.7 Example Scenarios and Expected Gains 201

5.3.8 Summary 204

5.4 Coverage and Capacity Optimisation 204

5.4.1 CCO with Adaptive Antennas 205

5.4.2 Performance Analysis for Antenna Parameter Optimisation Based CCO 208

5.4.3 CCO with TX Power 216

5.5 RACH Optimisation 217

5.5.1 General 217

5.5.2 PRACH Configuration 218

5.5.3 RACH Configuration 219

5.5.4 RACH/PRACH Configuration Example 221

5.5.5 RA Performance 222

5.5.6 Self-Optimisation Framework 223

5.5.7 UE Reporting 223

5.5.8 Inter-eNB Communication 225

5.6 RRM and SON (Interference Coordination, P0 Optimisation) 226

5.6.1 Interference Coordination 226

5.6.2 P0 Optimisation 230

References 232

6. Self-Healing 235

6.1 Introduction 236

6.1.1 3GPP Use Cases 236

6.1.2 3GPP Self-Healing Process and its Management 237

6.1.3 Cell Degradation Management 238

6.2 Cell Degradation Detection 242

6.3 Cell Degradation Diagnosis and Prediction 248

6.3.1 Rule Based Systems 250

6.3.2 Bayesian Networks 251

6.3.3 Case Based Reasoning 253

6.3.4 Neural Networks 255

6.3.5 Active Measurements 256

6.3.6 Prediction 257

6.4 Cell Outage Compensation 259

6.4.1 Activation of Cell Outage Compensation 260

6.4.2 Means of Cell Outage Compensation 260

6.4.3 Interaction between Cell Outage Compensation and Self-Configuration Functions 263

References 264

7. Supporting Function: Minimisation of Drive Tests (MDT) 267

7.1 Introduction 267

7.1.1 General 267

7.1.2 History and Background 269

7.2 Relation to SON 272

7.3 Requirements 273

7.4 Use Cases 275

7.4.1 Operator Scenarios 276

7.4.2 Coverage Optimisation 277

7.4.3 Mobility Optimisation 281

7.4.4 Capacity Optimisation 281

7.4.5 Parameterisation for Common Channels 282

7.4.6 QoS Verification 282

7.5 Overall Architecture 283

7.6 Managing MDT 285

7.6.1 Subscriber and Equipment Trace 285

7.6.2 MDT Configuration Parameters 285

7.6.3 Subscription Based MDT 287

7.6.4 Area Based MDT 292

7.6.5 Supporting Functionality in the Management System 293

7.6.6 MDT Reporting 293

7.7 MDT Radio Interface Procedures 295

7.7.1 Immediate MDT 296

7.7.2 Logged MDT 298

7.7.3 RLF Reporting 303

7.7.4 Measurement Parameters 305

7.7.5 Location Information 308

7.8 Conclusion 309

References 310

8. SON for Core Networks 311

8.1 Introduction 311

8.2 SON for Packet Core Networks 311

8.2.1 Packet Core Element Auto-Configuration 311

8.2.2 Automatic Neighbour Relation 313

8.2.3 S1 Flex (MME Pooling) 314

8.2.4 Signalling Optimisation 315

8.2.5 Latency Optimisation 317

8.2.6 Fast Gateway Convergence with Bidirectional Forward Detection 318

8.2.7 Dynamic IP Pool Allocation 318

8.2.8 Energy Saving 319

8.3 SON for Voice Core Networks 319

8.3.1 Voice Over IP Quality Monitoring and Management 319

8.3.2 Resource Optimisation in Voice Core Network 320

References 321

9. SON Operation 322

9.1 SON Function Interactions 323

9.1.1 Spatial Characteristic 324

9.1.2 Temporal Characteristic 324

9.1.3 Categories of SON Conflicts 326

9.1.4 Network Parameters Related to SON Functions 329

9.1.5 Examples for Conflicts between SON Functions 330

9.2 Coordination of SON Functions 334

9.2.1 Basic Options for SON Coordination 334

9.2.2 Goals of SON Function Coordination 338

9.2.3 SON Coordination Function Concept 340

9.2.4 Coordination Schemes 346

9.2.5 Related Work 352

9.2.6 SON Function Coordination Example 352

9.3 Conclusions 355

References 356

10. SON for Heterogeneous Networks (HetNet) 357

10.1 Introduction 357

10.2 Standardisation and Network Architecture 359

10.2.1 Network Architecture for HetNet 361

10.3 Self-Configuration 362

10.3.1 Auto-Connectivity and -Commissioning 363

10.3.2 Automatic Site Identification and Hardware-to-Site Mapping 364

10.3.3 Automatic Neighbour Relations (ANR) 365

10.4 Self-Optimisation: Interference Management 365

10.4.1 Interference Characteristics in HetNet Scenarios 365

10.4.2 Basic Interference Management Techniques 366

10.4.3 Scenarios with Macro eNBs and Micro/Pico eNBs 369

10.4.4 Enhanced Time-Domain Interference Management: eICIC 370

10.4.5 Outlook on Further Interference Management Innovations 374

10.5 Self-Optimisation: Mobility Aspects; MRO and Traffic Steering 375

10.5.1 Mobility Robustness Optimisation 375

10.5.2 Multi-Layer Traffic Steering and Load Balancing 377

10.5.3 IEEE 802.11 (WiFi) Integration 378

References 378

11. Future Research Topics 379

11.1 Future Mobile Network Scenarios 379

11.1.1 Heterogeneous Networks 379

11.1.2 Cloud RAN 380

11.1.3 Requirements for Future OAM Systems 381

11.2 Cognitive Radio Networks (CRN) 381

11.2.1 From SON to CRN 381

11.2.2 Definitions 382

11.2.3 Framework 383

11.2.4 Artificial Intelligence 385

11.3 Applications 387

11.3.1 Self-Configuration 387

11.3.2 Self-Optimisation 387

11.3.3 Self-Healing 388

11.3.4 Operation 388

11.4 Conclusion 389

References 389

Index 391

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