RF Imperfections in High-Rate Wireless Systems: Impact and Digital Compensation

ISBN-13: 9789048177578 / Angielski / Miękka / 2010 / 320 str.

Tim Schenk

Opis

This book takes a modern, multidisciplinary view on radio system - sign: the advantages of digital signal processing are exploited to satisfy the ever increasing demands on better performing, ?exible radio f- quency (RF) circuits. By accepting that analog circuits are inherently imperfect, but by searching for methods to mitigate and compensate for this, signi?cant steps can be made to improve the overall system so- tion. This is in contrast to the more traditional approach of designing RF circuits themselves to satisfy the demanding speci?cations set by current standards. Wireless communication has progressed dramatically in past years. Yet, the main research challenges changed focus to sustain this growth over many decades. In the early days, the main challenge of radio c- munications was to cover large distances. When in late 1980s, digital mobile communication emerged as a precursor to today s mass-market cell phones, the priority shifted to achieving reliable communication over a di?cult, i. e., time-varying and frequency-selective mobile ch- nel. About a decade or research in many institutes around the world has been devoted to this challenge, exploiting the opportunities given by increasing computational power in digital circuits. Today we face a di?erent paradigm: the technology for analog front-ends progress sign- icantly slower than that of digital processors. So the imperfections of the RF have increasingly become the major bottleneck in our drive - wards faster, yet more power-e?cient radio circuits."

Spis treści

Foreword. Preface. 1. INTRODUCTION. 1.1 Wireless communications. 1.2 OFDM. 1.3 MIMO . 1.4 RF transceiver impairments. 1.5 Outline of the book. 2. MULTIPLE-ANTENNA OFDM SYSTEMS. 2.1 Introduction. 2.2 Channel modelling. 2.3 System modelling. 2.4 Conclusions . 3. DESIGN AND IMPLEMENTATION OF A MIMO OFDM SYSTEM. 3.1 Introduction. 3.2 Transmission format and preamble design. 3.3 Frequency synchronisation. 3.4 Channel estimation. 3.5 Timing synchronisation. 3.6 Multiple-antenna OFDM system implementation. 3.7 Conclusions. 4. PHASE NOISE. 4.1 Introduction. 4.2 System and phase noise modelling. 4.3 Impact and distribution of the ICI term. 4.4 ICI-caused error term in MIMO OFDM. 4.5 Compensation of the CPE. 4.6 Compensation of the ICI. 4.7 Conclusions. 5. IQ IMBALANCE. 5.1 Introduction. 5.2 System and IQ imbalance modelling. 5.3 Impact of IQ imbalance on system performance. 5.4 Preamble based estimation and mitigation. 5.5 Decision-directed based mitigation. 5.6 Conclusions. 6. NONLINEARITIES. 6.1 Introduction. 6.2 System and nonlinearities modelling. 6.3 Impact of nonlinearities on system performance. 6.4 PAPR reduction by spatial shifting. 6.5 RX-based correction of nonlinearities. 6.6 Conclusions. 7. A GENERALISED ERROR MODEL. 7.1 Introduction. 7.2 Error model. 7.3 Performance evaluation. 7.4 Numerical results. 7.5 Conclusions. 8. DISCUSSION AND CONCLUSIONS. 8.1 Summary and conclusions. 8.2 Scope of future research. Glossary. Appendices. A MSE in CFO estimation. B MSE in channel estimation. C Measurement setup. D Proof of Theorem 4.1. E Orthonormal polynomial basis. References. Index.

Blurb

Wireless communication systems are persistently applying wider bandwidths, larger signal dynamics and higher carrier frequencies to fulfil the demand for higher data rates. This results in an ever increasing demand on the performance of low-cost and power-efficient radio frequency (RF) front-ends. Since the RF technology is, consequently, pushed to its operation boundaries, the intrinsic imperfections of the RF IC technology are more and more governing the system performance of wireless modems.

RF Imperfections in High-rate Wireless Systems therefore presents a new vision on the design of wireless communication systems. In this approach the imperfections of the RF front-ends are accepted and digital signal processing algorithms are designed to suppress their impact on system performance.

To illustrate this approach, the book focuses on multiple-antenna orthogonal frequency division multiplexing (MIMO OFDM), which will be applied as basis for the majority of near-future high-rate wireless systems. The basics of MIMO OFDM are introduced and the typically required signal processing in the implementation of such systems is elucidated. The book treats several of the front-end impairments that seriously affect the performance of MIMO OFDM systems: carrier frequency offset, phase noise, IQ imbalance and nonlinearities. To provide an in-depth understanding of the impact of these RF imperfections, analytical performance results are presented in the book. These results are then used to design different compensation approaches based on digital baseband processing.

RF Imperfections in High-rate Wireless Systems is of interest to wireless system designers, who want to familiarise with the digital compensation of RF imperfections. For researchers in the field of wireless communications this book provides a valuable overview of this emerging research topic.

Foreword by Jean-Paul Linnartz