Efficient Methods for WCDMA Radio Network Planning and Optimization (eBook)

Dr. Ulrich Türke promovierte bei Prof. Dr. Carmelita Görg am Fachbereich für Physik und Elektrotechnik der Universität Bremen. Er ist als Experte für Funknetzplanung und –optimierung bei der atesio GmbH in Berlin tätig.

Preface 6
Abstract 8
Contents 10
List of Abbreviations 14
List of Symbols 18
List of Figures 22
List of Tables 25
Chapter 1 Introduction 26
Chapter 2 The WCDMA Air Interface 30
2.1 UMTS Network Architecture 31
2.2 UTRA-FDD Protocols 33
2.3 Radio Resource Management 44
Chapter 3 Modeling the Wireless Transmission Channel 50
3.1 Macro Path Loss Prediction 51
3.2 Shadow Fading 56
3.3 Fast Fading 60
3.4 Antenna Modeling 61
3.5 Signal and Interference Levels 64
Chapter 4 Monte-Carlo Snapshot Analysis 70
4.1 The Monte-Carlo Method 71
4.2 Simple Analysis Example 74
4.3 Variance Reduction Techniques 80
4.4 Conclusions 91
Chapter 5 Monte-Carlo Snapshot Analysis for WCDMA Network Performance Evaluation 92
5.1 Basic Analysis Loop 92
5.2 Snapshot Generation 93
5.3 Modeling of Dynamics 95
5.4 System Constraints and Limits 96
5.5 Cell Based Radio Performance Evaluation 98
5.6 Resource Scheduling 106
5.7 Method Extensions 117
5.8 Application of Variance Reduction Techniques 118
5.9 Validation of Results 128
5.10 Conclusions 130
Chapter 6 Analytical Performance Evaluation 132
6.1 Static Load Estimation 133
6.2 Statistical Load Estimation 141
6.3 Extended Statistical Load Estimation 145
6.4 Evaluation of Per Pixel Quantities 152
6.5 Practical Implementation 160
6.6 Conclusions 161
Chapter 7 Automated Network Optimization 162
7.1 Optimization Parameters and Targets 162
7.2 Optimization based on Fast Heuristic 163
7.3 Search Based Optimization 167
7.4 Application Example 175
7.5 Conclusions 177
Chapter 8 Conclusions and Outlook 180
Appendix A Generating Correlated Random Variables 182
Bibliography 184

Chapter 2 The WCDMA Air Interface (p. 5)

WCDMA is the most widely adopted air interface standard for third generation (3G) mobile networks. 3G networks have been designed to supersede second generation (2G) networks, i.e. GSM (Europe and large parts of the world), cdmaOne (Americas), D-AMPS (Americas), and PDC (Japan). The main advances of 3G systems compared with 2G systems are [HT04]:

• Higher user peak data rates (several Mbps).

• Dynamic adaptation of user data rates ("bandwidth on demand").

• Asymmetric uplink and downlink data rates to fit usual Packet-Switched (PS) traffic characteristics, e.g. web browsing, ftp downloads.

• Support of Quality of Service (QoS) differentiation, e.g. in terms of error rates and delay.

• Multiplexing of services with different quality and data rate requirements on a single connection.

• Improved spectrum efficiency (higher system throughput per unit of allocated frequency spectrum).

Work on the development of 3G systems started in 1992 by the International Telecommunications Union (ITU). Original target of the ITU activities was to define one global International Mobile Telecommunications-2000 (IMT-2000) standard that operates in a common frequency band around 2 GHz in the largest world markets for mobile communication, namely USA, Europe, and Asia. In the USA, however, the frequency band considered by the ITU for IMT-2000 was already occupied by 2G networks (GSM 1900) and for satellite communication (in the 2.1 GHz band).

The 3G networks currently being deployed in the USA hence partly reuse the frequency spectrum originally auctioned for GSM 1900 but in particular utilize different frequencies bands. This drives the need for several types of base station equipment and costly multi-band user equipment to provide global handsets. This is similar to the present situation in 2G networks that ITU intended to overcome with 3G.

Several competing standards have been defined by the standardization bodies in the IMT- 2000 framework. In 1999 the ITU approved five air interfaces for IMT-2000. The most relevant of these are WCDMA, CDMA2000, TD-SCDMA, and EDGE as a direct successor of GSM. CDMA2000 is the successor of cdmaOne in the USA. CDMA2000 utilizes a smaller frequency band than WCDMA to simplify the usage of the fragmented spectrum. TD-SCDMA is a standard to be deployed in China.

WCDMA is the air interface used by the Universal Mobile Telecommunications System (UMTS), which is specified and brought into ITU by the 3rd Generation Partnership Project (3GPP). The most important standardization bodies contribute to 3GPP, i.e. ARIB (Japan), ATIS (USA), CCSA (China), ETSI (Europe), TTA (Korea), and TTC (Japan). WCDMA is called Universal Terrestrial Radio Access (UTRA) within 3GPP. It covers two modes of operation, that is UTRA-FDD (Frequency Division Duplex) and UTRATDD (Time Division Duplex).

UTRA-FDD uses paired frequency bands for Uplink (UL) and Downlink (DL) data transmission, whereas UTRA-TDD utilizes a common frequency band for both directions and adjusts the time domain portion assigned for UL and DL transmission dynamically.