RF Analog Impairments Modeling for Communication Systems Simulation E-Book

Lydi Smaini

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 219

Veröffentlichungsjahr: 2012

Beschreibung

With the growing complexity of personal mobile communication systems demanding higher data-rates and high levels of integration using low-cost CMOS technology, overall system performance has become more sensitive to RF analog front-end impairments. Designing integrated transceivers requires a thorough understanding of the whole transceiver chain including RF analog front-end and digital baseband. Communication system engineers have to include RF analog imperfections in their simulation benches in order to study and quantify their impact on the system performance.

Here the author explores key RF analog impairments in a transceiver and demonstrates how to model their impact from a communication system design view-point. He discusses the design aspects of the front end of transceivers (both receivers and transmitters) and provides the reader with a way to optimize a complex mixed-signal platform by taking into account the characteristics of the RF/analog front-end.

Key features of this book include:

• Practical examples illustrated by system simulation results based on WiFi and mobile WiMAX OFDM transceivers
• An overview of the digital estimation and compensation of the RF analog impairments such as power amplifier distortion, quadrature imbalance, and carrier and sampling frequency offsets
• An exposition of the challenges involved in the design of both RF analog circuits and DSP communication circuits in deep submicron CMOS technology
• MATLAB® codes for RF analog impairments models  hosted on the companion website

Uniquely the book bridges the gap between RFIC design specification needs and communication systems simulation, offering readers RF analog impairments modeling knowledge and a comprehensive approach to unifying theory and practice in system modelling. It is of great value to communication systems and DSP engineers and graduate students who design communication processing engines, RF/analog systems and IC design engineers involved in the design of communication platforms.

Leseprobe

Table of Contents

Title Page

Copyright

Dedication

Preface

Acknowledgments

About the Author

Chapter 1: Introduction to Communication System-on-Chip, RF Analog Front-End, OFDM Modulation, and Performance Metrics

1.1 Communication System-on-Chip

1.2 RF AFE Overview

1.3 OFDM Modulation

1.4 SNR, EVM, and Eb/N0 Definitions and Relationship

References

Chapter 2: RF Analog Impairments Description and Modeling

2.1 Introduction

2.2 Thermal Noise

2.3 Oscillator Phase Noise

2.4 Sampling Jitter

2.5 Carrier Frequency Offset

2.6 Sampling Frequency Offset

2.7 I and Q Mismatch

2.8 DAC/ADC Quantization Noise and Clipping

2.9 IP2 and IP3: Second- and Third-Order Nonlinearities

2.10 Power Amplifier Distortion

References

Chapter 3: Simulation of the RF Analog Impairments Impact on Real OFDM-Based Transceiver Performance

3.1 Introduction

3.2 WLAN and Mobile WiMAX PHY Overview

3.3 Simulation Bench Overview

3.4 WiFi OFDM and Mobile WiMAX Signals PAPR

3.5 Transmitter Impairments Simulation

3.6 Receiver Impairments Simulation

3.7 Adaptive Modulation Illustration

3.8 Summary

References

Chapter 4: Digital Compensation of RF Analog Impairments

4.1 Introduction

4.2 CFO Estimation and Correction

4.3 SFO Estimation and Correction

4.4 IQ Mismatch Estimation and Correction

4.5 Power Amplifier Linearization

4.6 Summary

References

Index

This edition first published 2012

© 2012, John Wiley & Sons Ltd

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Library of Congress Cataloging-in-Publication Data

Smaini, Lydi, 1974-

RF analog impairments modeling for communication systems simulation :

application to OFDM-based transceivers / Lydi Smaini.

p. cm.

ISBN 978-1-119-99907-2 (hardback)

1. Radio– Transmitter-receivers– Simulation methods. 2. Electromagnetic

interference. 3. Signal integrity (Electronics) 4. Telecommunication

systems– Simulation methods. 5. Orthogonal frequency division multiplexing.

I. Title.

TK7867.2.S63 2012

621.382– dc23

To my parents, Zina and Rabah.

To my sisters, Nadine and Assia.

To my brothers, Malik and Dalil.

To my childhood friend, Djamel.

Preface

Modern digital communications transceivers can be decomposed into two main parts: the radio frequency (RF) analog front-end, which transmits and receives the analog signal, and the digital baseband, which is responsible for the digital signal processing (DSP) and data demodulation. The “virtual” frontier is delimited by the digital to analog conversion in transmission, and by the analog to digital conversion in reception. The digital baseband is commonly studied and simulated by communication system and DSP engineers based on standard requirements, which specify the modulation type and the system performance in terms of bit or packet error rate. On the other hand, the RF analog front-end specifications are often derived by the RF analog engineers themselves using, for example, Excel spreadsheets for calculating signal-to-noise ratio (SNR) or error vector magnitude (EVM) from basic and classical formulas based on dual- or single-tone tests historically coming from laboratory measurements. Actually, these RF analog analysis methods do not take into account the signal spectral properties and the transceiver bandwidth; consequently, there is a gap between the RF analog front-end specifications and the digital baseband simulations which often introduces misunderstanding during the transceiver design.

Nowadays, with the growing complexity of personal mobile communication systems demanding higher data-rates and high levels of integration using low-cost complementary metal oxide semiconductor (CMOS) technology, overall system performance has become much more sensitive to RF analog font-end impairments. Consequently, communication system and DSP engineers have to understand and to include these RF analog imperfections in their simulation benches in order to measure their impact on the system performance. In addition, in deep-submicrometer CMOS technology (nanometer) the digital part of the transceiver naturally shrinks with the process ratio whereas the RF analog part remains fairly constant (only 10 % size reduction in good cases). As a result, in terms of die area and thus cost reduction, the analog part remains the major bottleneck of CMOS transceiver integration and generally requires a non-negligible redesign effort if one wants to reduce its area and power consumption. To surmount this integration issue, a new trend is to design suboptimal RF analog front-ends, called “dirty RF” in recent literature, and to compensate their impairments with DSP. Designing such integrated transceivers requires a thorough understanding of the whole transceiver chain, including RF analog engineering and DSP.

The aim of this book is to provide the reader with theoretical and practical RF analog system modeling knowledge and examples directly applicable to advanced transceiver studies and simulations. Furthermore, we endeavor to make a bridge between RF analog designers and communication system/DSP engineers who often use different tools and vocabulary even when specifying the same thing. We theoretically describe the impact of the RF analog imperfections on orthogonal frequency division multiplexing (OFDM) modulation, which has widely recognized advantages and is utilized in latest generation communication systems. To illustrate the theory we present simulation results comparing the impact of the transceiver imperfections on two well-known deployed standards, WiFi (802.11a/g) and mobile WiMAX (802.16e).

The organization of the book is as follows:

In Chapter 1 we introduce the challenges of the integration of communication systems on-chip, especially those using CMOS technology. We will also give an overview of the major RF analog front-end architectures, the main principles of OFDM modulation which is now deployed in 4G mobile communications, and finally an introduction to RF analog system performance metrics and baseband simulation.

Chapter 2 deals with the principal RF analog impairments encountered in communication transceivers. We describe them mathematically in order to derive models which can be incorporated into any system simulation, and also to study their theoretical impact on the system performance with a special focus on OFDM modulation.

In Chapter 3, system simulation results based on WiFi and mobile WiMAX OFDM transceivers are presented. All the RF analog impairments described in Chapter 2 are modeled and simulated in order to study their impact individually on the system performance, both in transmission and reception.

Finally, digital estimation and compensation of the RF analog impairments is overviewed in Chapter 4: carrier and sampling frequency offsets in OFDM reception, quadrature imbalance, as well digital pre-distortion in transmission are addressed.

Acknowledgments

First, I would like to thank Frederic Declercq, Analog IC design manager at Marvell Switzerland, and Kevin Koehler, Staff DSP engineer at Marvell Switzerland, for having accepted to review the whole manuscript. Their valuable comments on both content and form, and our technical discussions allowed me to improve the book from its original version to the final delivery. Thanks also to Nils Rinaldi, Project manager at EPFL, for his comments on Chapter 2.

I am grateful to Patrick Clement, Director of Marvell Switzerland, for his trust and encouragement to write this book.

I wish to thank Peter Mitchell, Publisher at John Wiley & Sons responsible for electrical and electronics engineering books, who proposed this book project to me. I also thank Liz Wingett, Project Editor at John Wiley & Sons, for her support and advice during the writing process.

Finally, I would like to thank my fiancée Laurence for her understanding, patience, and support.

About the Author

Dr Lydi Smaini was born in Tizi-Ouzou, Algeria, on 27 July 1974. He received his M.S. and Ph.D. degrees in electronics from the University of South Toulon-Var, France, in 1998 and 2001, respectively, specializing in radio propagation, telecommunications, and remote sensing. His thesis work focused on pulse compression techniques and signal processing for atmospheric radars.

After graduation he worked for one year as an R&D electronics engineer for ALTEN, Marseille, France, where he developed a frequency agile radar transponder beacon (S and X bands) for navigation aid.

From 2002 to 2006 he was with STMicroelectronics in the RF System and Architecture Group for wireless communications, Geneva, Switzerland, where he worked on ultra wide-band impulse radio, 3G cellular phones, and advanced radio architectures for orthogonal frequency division multiple access (OFDMA) technology.

Dr Smaini joined Marvell Switzerland in July 2006, Etoy, Switzerland, where he is currently leading the RF System and DSP group working on deep sub-micrometer complementary metal oxide semiconductor (CMOS) telecommunication transceivers.

Chapter 1

Introduction to Communication System-on-Chip, RF Analog Front-End, OFDM Modulation, and Performance Metrics

1.1 Communication System-on-Chip

1.1.1 Introduction

Radio frequency (RF) communication systems use RFs to transmit and receive information such as voice and music with FM, or video with TV, and so on (Steele, 1995; Rappaport, 1996; Haykin, 2001). From a general point of view RF communication is simply composed of an RF transmitter sending the information and an RF receiver recovering the information (Figure 1.1). Below are basic definitions of the vocabulary commonly used in communication systems:

Signal:

Information (data, image, music, voice, …) we want to transmit and receive.

Carrier frequency

: RF sinusoidal waveform, called a carrier because it is used to “carry” the signal from the transmitter to the receiver.

MODulation

: Modifying the carrier waveform in order to convey the information (signal) in transmission.

DEModulation

: Extracting the signal (i.e., the information) from the carrier frequency in reception.