Software Radio A Modern Approach to Radio Engineering

by Reed, Jeffrey H.

• ISBN13: 9780130811585
• ISBN10: 0130811580
• Edition: 1st
• Format: Paperback
• Copyright: 2002-05-20
• Publisher: Prentice Hall

Summary

The definitive engineer's guide to designing and building software-based radios, this book introduces the key concepts of software radio design and covers every issue and technique engineers must understand to successfully utilize digital signal processing (DSP) in their radio systems and subsystems.

Author Biography

JEFFREY H. REED, Director of the Mobile and Portable Radio Research Group (MPRG) and Associate Professor of Electrical Engineering at Virginia Tech, specializes in spread spectrum, position location, DSP, interference rejection, modem design, smart antennas, and software radios. Dr. Reed is co-editor of five textbooks.

Table of Contents

Preface	xv
Acknowledgments	xix
Introduction to Software Radio Concepts	1	(10)
The Need for Software Radios	1	(1)
What Is a Software Radio?	2	(1)
Characteristics and Benefits of a Software Radio	3	(3)
Design Principles of a Software Radio	6	(2)
Questions	8	(3)
Radio Frequency Implementation Issues	11	(44)
The Purpose of the RF Front-End	11	(2)
Dynamic Range: The Principal Challenge of Receiver Design	13	(1)
Receiver Front-End Topologies	14	(7)
Characteristics of the Topologies	14	(1)
Topologies	15	(6)
Enhanced Flexibility of the RF Chain with Software Radios	21	(1)
Importance of the Components to Overall Performance	21	(12)
Antennas	21	(5)
Duplexer and Diplexer	26	(1)
RF Filter	26	(1)
Low Noise Amplifier	27	(1)
Image Reject and IF Filters	27	(1)
RF Mixer	27	(1)
Local Oscillator	28	(1)
Automatic Gain Control	29	(3)
Analog to Digital Converter	32	(1)
Transmitter Architectures and Their Issues	33	(2)
Noise and Distortion in the RF Chain	35	(7)
Noise Characterization	35	(3)
Distortion Characterization	38	(4)
ADC and DAC Distortion	42	(1)
Predistortion	43	(6)
Flexible RF Systems Using Microelectromechanical Systems	49	(3)
Conclusion	52	(1)
Questions	53	(2)
Multirate Signal Processing	55	(72)
Introduction	55	(2)
Cost	55	(1)
Flexibility	56	(1)
Overview of the Chapter	57	(1)
Sample Rate Conversion Principles	57	(39)
Decimation	58	(4)
Interpolation	62	(15)
Two Multirate Identities	77	(1)
Non-Integer-Rate Conversion	78	(1)
Sampling Rate Conversion by Stages	79	(8)
Cascaded Integrator Comb Filter	87	(9)
Polyphase Filters	96	(5)
Polyphase Decimation	96	(2)
Polyphase Interpolation	98	(3)
Digital Filter Banks	101	(13)
Implementation	103	(1)
DFT Filter Banks	103	(9)
Transmultiplexers	112	(2)
Timing Recovery in Digital Receivers Using Multirate Digital Filters	114	(10)
Timing Recovery in a Classical Analog Receiver	117	(1)
Timing Recovery in the Digital Domain Only	117	(3)
Early-Late Gate Synchronizer	120	(1)
Timing Offset Control Using the Early-Late Gate Principle	120	(4)
Conclusion	124	(1)
Questions	125	(2)
Digital Generation of Signals	127	(42)
Introduction	127	(2)
Comparison of Direct Digital Synthesis with Analog Signal Synthesis	129	(2)
Approaches to Direct Digital Synthesis	131	(9)
Pulse Output Direct Digital Synthesis	131	(2)
ROM Look-Up Table Approach	133	(1)
Phase Truncation Distortion	133	(6)
Analysis of the Output Sequence	139	(1)
Analysis of Spurious Signals	140	(3)
Spurious Components due to Periodic Jitter	143	(1)
Bandpass Signal Generation	144	(2)
Performance of Direct Digital Synthesis Systems	146	(2)
Experimental Findings	146	(1)
Use of Hybrid Systems	147	(1)
Hybrid DDS-PLL Systems	148	(1)
Applications of Direct Digital Synthesis	148	(2)
Generation of Random Sequences	150	(7)
Types of Sequences and Their Properties	150	(3)
Randomization with the Wheatley Procedure	153	(4)
ROM Compression Techniques	157	(6)
Interpolation Using Taylor's Series Expansion	158	(2)
Interpolation Using Trigonometric Identities	160	(3)
Sine-Phase Difference Algorithm Approach	163	(1)
Modified Sine-Phase Difference Approach (Parabolic Approximation)	164	(2)
Conclusion	166	(1)
Questions	167	(2)
Analog to Digital and Digital to Analog Conversion	169	(94)
Introduction	169	(2)
Parameters of Ideal Data Converters	171	(24)
Sampling Process	171	(13)
Quantization	184	(11)
Parameters of Practical Data Converters	195	(29)
Generic Data Converter Physical Models	195	(4)
Practical Transfer Characteristic Considerations	199	(3)
Dynamic Range Considerations	202	(6)
Practical Timing Issues	208	(9)
Analog Bandwidth	217	(1)
Power Consumption	217	(4)
Impact of Noise and Interference on Dynamic Range Requirements	221	(3)
Techniques to Improve Data Converter Performance	224	(8)
Dithering	225	(3)
Automatic Gain Control	228	(4)
Common ADC and DAC Architectures	232	(24)
Parallel Structures: Flash ADCs, String DACs, and Binary Structures	232	(4)
Segmented Structures: Folding and Interpolating ADC and Segmented Ladder DAC	236	(6)
Iterative Structures: Subranging/Pipelined/Half Flash ADC, Successive Approximation ADC	242	(4)
Sigma-Delta Structures: ADC and DAC	246	(10)
Conclusion	256	(3)
Questions	259	(4)
Smart Antennas	263	(76)
Introduction	263	(1)
Vector Channel Modeling	264	(10)
Array Steering Vectors	265	(5)
Multipath Channel Models	270	(3)
Multi-User Channel Models	273	(1)
Benefits of Smart Antennas	274	(2)
Beamforming	275	(1)
Space-Time Equalization	276	(1)
Diversity	276	(1)
Structures for Beamforming Systems	276	(6)
Multiple Fixed-Beam Antenna Array	278	(1)
Fully Adaptive Array	278	(4)
Relative Benefits and Trade-Offs of Switched Beam and Adaptive Array Systems	282	(1)
Smart Antenna Algorithms	282	(18)
Diversity Combining Techniques	283	(6)
Adaptation Algorithms Using Training Sequences	289	(3)
Blind Algorithms	292	(8)
Diversity and Space-Time Adaptive Signal Processing	300	(9)
Algorithms for Receiver STAP	301	(7)
Overloaded Array Processing	308	(1)
Algorithms for Transmit STAP	309	(7)
Space-Time Pre-Filtering	309	(1)
Space-Time Trellis Coding	310	(4)
A Simple Transmit Diversity Scheme	314	(2)
Hardware Implementation of Smart Antennas	316	(5)
Digital Beamforming Receiver Implementation	317	(1)
Digital Beamforming Transmitter Implementation	317	(2)
Component Issues	319	(2)
Array Calibration	321	(2)
Remote Transmitter Approach	321	(1)
Test-Tone Approach	322	(1)
Virginia Tech Space-Time Adaptive Radio Case Study	323	(10)
Overview of the VT STAR Architecture	324	(1)
RF Design of VT STAR	325	(2)
Software Issues for VT-STAR	327	(6)
Key Design Issues of VT-STAR	333	(1)
Conclusion	333	(2)
Questions	335	(4)
Digital Hardware Choices	339	(52)
Introduction	339	(1)
Key Hardware Elements	340	(2)
DSP Processors	342	(29)
DSP Core	342	(1)
DSP Architectures	342	(5)
Numeric Representation	347	(3)
Addressing	350	(3)
Pipelining	353	(2)
Peripherals and Additional Features	355	(1)
Multi-Processing	355	(2)
Multi-Processing Using a Real-Time Operating System	357	(1)
The Software Design Cycle	358	(2)
Maximizing Performance	360	(8)
Benchmarks and Performance Evaluation	368	(2)
Case Study: TMS320C54x Series DSPs	370	(1)
Field Programmable Gate Arrays	371	(8)
Operation of an SRAM-Based FPGA Cell	371	(2)
Implementing DSP Functions in FPGAs	373	(1)
FPGA Architectures	373	(4)
Applications of FPGAs to Software Radios	377	(1)
Design Principles using FPGAs	378	(1)
Trade-Offs in Using DSPs, FPGAs, and ASICs	379	(1)
Power Management Issues	379	(7)
DSP Power Management	380	(1)
Low-Power VLSI Design	381	(2)
Architectural-/System-Level Approaches	383	(3)
Using a Combination of DSPs, FPGAs, and ASICs	386	(1)
Conclusion	387	(1)
Questions	388	(3)
Object Oriented Representation of Radios and Network Resources	391	(52)
Introduction	391	(1)
Networks	392	(13)
System Layers	395	(1)
Switching	396	(1)
Quality-of-Service	396	(1)
Internet Protocol	397	(6)
Asynchronous Transfer Mode	403	(1)
Networks and Software Radios	404	(1)
Object-Oriented Programming	405	(11)
Objects	406	(5)
Java	411	(3)
Java and Software Radios	414	(1)
The Radio Virtual Machine	415	(1)
Object-Oriented Software and Software Radios	415	(1)
Object Brokers	416	(8)
Common Object Request Broker Architecture	419	(3)
Software Radio Implementation Issues	422	(2)
Object Brokers and Software Radios	424	(1)
Mobile Application Environments	424	(10)
MExE	427	(5)
Service Discovery	432	(1)
Mobile Application Environments and Software Radios	432	(1)
Security in Software Radio	433	(1)
Joint Tactical Radio System	434	(6)
Hardware Classes	434	(1)
SCA Structure	435	(5)
Conclusion	440	(1)
Questions	441	(2)
Case Studies in Software Radio Design	443	(72)
Introduction and a Historical Perspective	443	(7)
Architectural Characteristics Intrinsic to a Software Radio	445	(1)
Architectural Characteristics Important to a Software Radio	446	(2)
Architectural Characteristics of Practical Software Radios	448	(2)
SPEAKeasy	450	(12)
SPEAKeasy Phase I	451	(4)
SPEAKeasy Phase II	455	(7)
SPEAKeasy Summary	462	(1)
JTRS	462	(19)
Goals of the SCA	465	(1)
Attributes of the SCA Developed from the PMCS Guidance Document	465	(1)
SCA Architectural Details	466	(9)
JTRS Summary	475	(1)
SDR Forum Architecture Details	476	(5)
Summary	481	(1)
Wireless Information Transfer System	481	(11)
Architecture Goals	483	(1)
Architecture Overview	483	(1)
Software Architecture	484	(1)
Hardware Architecture	484	(2)
Architectural Details	486	(4)
WITS Summary	490	(2)
SDR-3000 Digital Transceiver Subsystem	492	(2)
Spectrum Ware	494	(15)
Spectrum Ware System Description	495	(1)
Input/Output	495	(1)
Programming Environment	496	(11)
Layered Radio Architecture Implementation Example	507	(2)
CHARIOT Summary	509	(1)
Conclusion	509	(3)
Questions	512	(3)
A RF ENGINEERING BOOKS AND TRADE PUBLICATIONS	515	(4)
Electronics	515	(1)
RF Circuit Design and S-Parameters	515	(1)
Filters	516	(1)
Microwaves	516	(1)
Oscillators	516	(1)
Phase Locked Loops and Frequency Synthesizers	516	(1)
Receivers and Systems	517	(1)
PSpice	517	(1)
Trade Publications and Periodicals	517	(1)
Web-Accessible Tutorial Materials	518	(1)
B THE COORDINATE ROTATION DIGITAL COMPUTER ALGORITHM	519	(12)
Introduction	519	(1)
CORDIC Overview	520	(1)
Derivation of the CORDIC Algorithm	520	(6)
Translating a Point Along a Circle of Radius R	520	(2)
Rotation Through Iterative Subrotations	522	(1)
Computationally Simplifying the Iterative Rotations	523	(1)
Putting the Equations in Final Form	524	(1)
Vectoring Mode	525	(1)
CORDIC Algorithm Performance	526	(1)
Extensions to the CORDIC Algorithm	527	(4)
References	531	(18)
Glossary of Acronyms	549	(8)
About the Author	557	(2)
About the Chapter Co-Authors	559	(2)
Index	561

Excerpts

Preface Software radios represent a major change in the design paradigm for radios in which a large portion of the functionality is implemented through programmable signal processing devices, giving the radio the ability to change its operating parameters to accommodate new features and capabilities. A software radio approach reduces the content of radio frequency (RF) and other analog components of traditional radios and emphasizes digital signal processing to enhance overall receiver flexibility. This change in the design paradigm for new radios has occurred so rapidly that it has left a significant void in the educational material available to train new radio engineers. Traditional radio engineering textbooks emphasize analog component-level design with little mention of the increasingly important role of digital signal processing in performing the central functions of the radio transceiver. Individual references covering the key analog and digital subsystems tend to be insufficient in that they fail to provide a full understanding of the interaction between these subsystems. I became acutely aware of this void when conducting research into the development of novel high-performance radios for the Defense Advanced Research Projects Agency (DARPA). While constructing radio prototypes, I found there was no comprehensive resource to which I could point my students for information on how to build DSP-based radios. This experience, combined with similar frustrations voiced by my colleagues from both academia and industry, has led me to write this book on modern radio design principles. My goal in developing this book was to provide this necessary understanding of the interaction of key subsystems. Software radios are emerging in commercial and military infrastructure. This growth is motivated by the numerous advantages of software radios. Ease of design--Traditional radio design requires years of experience and great care on the part of the designer to understand how the various system components work in conjunction with one another. The time required to develop a marketable product is a key consideration in modern engineering design, and software radio implementations reduce the design cycles for new products, freeing the engineer from much of the iteration associated with analog hardware design. It is possible to design many different radio products using a common RF front-end with the desired frequency and bandwidth in conjunction with different signal processing software. Ease of manufacture--No two analog components have precisely identical performance, necessitating rigorous quality control and testing of radios during the manufacturing process. However, given the same input, two digital processors running the same software will produce identical outputs. Thus, the move to digital hardware reduces the costs associated with manufacturing and testing the radios. Multimode operation--The explosive growth of wireless has led to a proliferation of transmission standards, and in many cases, it is desirable that a radio operates according to more than one standard. For example, wireless carriers throughout the U.S. are deploying systems that make use of the GSM (Global System for Mobile Communications) standard in some markets and the IS-95 Code Division Multiple Access (CDMA) standard in other markets. Furthermore, the advent of third-generation wireless has introduced a number of standards within that framework. Traditionally, multimode operation has required multiple complete sets of hardware, increasing the size and cost of the radio. However, a software radio can change modes by simply loading appropriate software into the memory. Use of advanced signal processing techniques--The availability of high speed signal processing on board the radio allows implementation of new receiver structures and signal processing techniques. Techniques such as adaptive antennas, interference rejection, and strong encryption, previously deemed too complex, are now finding their way into commercial systems as the performance of digital signal processors continues to increase. The impact will be enhanced range and quality of service to the consumer while reducing overall infrastructure cost for the service provider. Fewer discrete components--A single high-speed digital processor may be able to implement many traditional radio functions such as synchronization, demodulation, error detection, and decryption of data, reducing the number of required components and decreasing the size and cost of a radio. Flexibility to incorporate additional functionality--Software radios may be modified in the field to correct unforeseen problems or upgrade the radio. For example, it may even be possible to transmit software upgrades to the radio, such as a new vocoder to handsets, to improve overall system performance. Another important improved functionality is the capability of self-diagnosis of the radio and network operations, which means improved reliability with less human intervention. Given these clear advantages and the increasing processing power available in commercial digital signal processing devices, I anticipate that radio engineers that software radios will become the standard approach for radio design. The challenge in creating the software radio is the broad scope of knowledge necessary, including digital signal processing algorithms, RF circuits, software methodologies, and digital circuits. The approach in this text is to provide an understanding of key areas in radio design for the digital signal processing engineer. For example, a digital signal processing engineer must know the ramifications of the choices in RF parameters and the resulting limitations to be able to understand the appropriate subsequent signal processing to account for these limitations. This book reviews critical and interdependent radio subsystems from the perspective of the DSP engineer. Chapter 1 provides a basic introduction to software radio concepts, discusses the benefits of software radios, and sets the stage for discussing software radio design. Digital signal processing engineers tend to know very little about RF engineering and, likewise, RF engineers tend to know very little about digital signal processing. However, to take full advantage of the software radio approach, these subsystems cannot be treated separately. Chapter 2 provides the digital signal processing engineer with fundamentals in constructing RF front-ends and describes processing that can be performed in the digital domain to overcome problem areas in RF design. Multirate digital signal processing uses different sample rates, and this is the topic of Chapter 3. This approach to signal processing is particularly important in software radios where bandwidths and sample rates are high initially and must be reduced for efficient subsequent processing. Multirate digital signal processing is commonly used to channelize the operating band into distinct communication channels. Multirate digital signal processing is also the foundation for modern synchronization techniques. Much of the flexibility of a software radio comes from being able to create arbitrary modulation types directly within the digital domain. In many cases, the direct digital synthesis methods used to generate these signals are more than just digitized realizations of analog techniques and afford the designer greater freedom in design signal waveforms. Chapter 4 surveys the topic of direct digital synthesis of modulated waveforms. Analog to digital converters and digital to analog converters, along with the power amplifier, are the most critical components in software radio design. The demands on these components can be very high. A rigorous understan