alization of Software Radio . ..
Joseph Mitola Ill
David Chester
uring the past five years, the software radio has emerged from militaryresearch to become a cornerstone of third-generation (3G) strategies for affordable high-performance regional and global communications. Although the first software radio technical paper in the literature was presented at theIEEENationalTelesystems Conferencein theunited States in 1992, the European Commission sponsored the first International Workshop on SoftwareRadiosinMay 1998.The First Asian Workshop on the Software Radio was sponsored by Keio University, Japan, in April 1998.And now, the softwareradio is described as a cornerstone in the evolution of GSM in publications of the GSM MoU Committee. In addition, industrial leaders like Toshiba, Nokia, and Motorola have described an intent to migrate from digital radios to software radios as the technology matures. So thekey questions onglobalization center not on I f , but on when and how the technology will enter the mainstream. This Feature Topic brings together articles from across the globe that begin to identify and address the key questions. Subsequent articles in hand for the new series on software and digitalsignalprocessing (DSP) inradiowill trackthe continuedglobal productization of the software radio. This feature topic itself was created by an editorial board comprising senior technical contributors from around the world. In Europe, Dr Thierry Turletti of INRIA, France, contributes his unique insight into computational complexity and benchmarking of radio software. He is joined by Dr. Walter H W. Tuttlebee of Roke Manor Research, United Kingdom, whose mix of military and commercial experience contributes balance and perspective. Dr. Tuttlebee also contributes to the global Software-Defined Radio (SDR) Forum as a leader in the development of both military and commercial software radio technology. Professor ShinichiroHaruyama,of Keio University,Japan, and organizer of the first Japanese workshop on the softwareradio, graciously serves as editor for the AsiaPacificregion.He had akeyrolein establishing Sony Corporation’s wireless communications laboratory. Dr. David Chester of the Harris Corporation, the scientist responsiblefor Harris Corporation’sSemiconductorDSP products for softwareradios, represents theunited States.Dave’sexperience also embraces historically military technology development with later commercialization. Finally, Joe Mitola of the MITRE Corporation organized this Feature Topic and serves as chief editor. The editorial board would like to express our appreciation to the authors andnumerous peer reviewerswho workedunder a very tight schedule to bring this Feature Topic to life. This feature topic had to be curtailed from a dozen publishable articles to just seven, but the breadth and quality of the articles led IEEE Communications Magazine to make a commitment to publish all the articles through a newly established Fea-
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Shinichiro Haruyama
Thierty Turletti
Walter Tuttlebee
ture Series on Software and DSP in Radio, which we are pleased to announce herewith. The present Feature Topicincludes articles on architecture, components, systems, and standards, aswillthe Feature Series.IEEE CommunicationsMagazineremains committed to publishing cutting-edge tutorials on the growing role of DSP and software in radio systems and technology. This Feature Topic provides a timely update on the progress of software radio since the flagship special issue of the magazine dedicated to the topicin May 1995.Mitola’slead article,“Technology Challenges in the Globalization of the Software Radio,” reviews the evolving concepts, architecture, and technology challenges, including the economics of the software radio. The focus is on continuingproductization and globalization, albeitwith different motivations in the United States, Europe, and Asia. This article introduces technical concepts and issues developed in subsequent articles.“Broadband RFStage Architecture for Software-Defined Radio for Handheld Terminal Applications” by HiroshiTsurumi andYasuo SuzukiofToshibaintroducesthe articles with a subsystem-level focus. This article highlights a novel direct conversion receiver RF design in which the R F signal is downconverted to zero I F for filtering and then upconverted for analog-to-digital conversion (ADC). Critical handset parameters are readily addressed with this novel approach. Dr. Bob Walden answers questions raised in the Mitola and Tsurumi articles in his discussion of “ADC Technology for Software Radios.” In addition to an overview of available products, Bob makes a convincing case that the nearly exponential progress observedin other microelectronicstechnologiesmay not fullyapply to ADCs. Moore’s Law calls for a doubling of processor capability every 18 months. Using a figure of merit defined as the product of samplingrate and useful dynamicrange, Walden defines the pace in ADC performance improvement as about one equivalent bit in six years. At sampling rates below 2 MHz, this is due to thermal noise. From ’2 MHz to 4 GHz, aperture jitter is the limiting factor. And above 4 GHz, comparator ambiguity equivalent to a circuit unity-current-gain frequency of 50 GHz is the limiting factor. Although the trend has slowed, the need for enhanced ADCs is attracting military and commercial investments. Dr. Dave Chester leverages Moore’s Law with “Digital I F Filter Technology for 3G Systems: A Tutorial.” Wideband digital filters first introduced in 1990 for the instrumentation marketplace acquired a single signal channel from awideband stream. Contemporary digital filters also extract multiple channels in parallel. Dr. Chester reviews the concepts and describes the product baseline that is emerging in this highly competitive segment of the software radio technology and marketplace. Continuingto leverage Moore’sLaw, Mark Cummingsand Shinichi-
IEEE Communications Magazine * February 1999
ro Haruyama describe the growing role of reconfigurable logic, notablyin field programmablegate arrays(FPGAs). Their article, “FPGA in the Software Radio,” compares FPGAs to the classical mix of application-specific integrated circuits (ASICs) and DSPs. Mark is Technical Chair of the SDR Forum (formerly the Modular Multifunction Information Transfer Systems or MMITS Forum). Professor Haryuama organized the First Asian Conference on Software Radios in April 1998. With such backgrounds, they are both keenly aware of intellectual property (IP) issues of FPGAs. Their article suggests the development of a pool of IP for 3GFPGAs as away to accelerate affordablesoftware radio productization.Solving IP is clearly necessary to broaden collaboration in radio products. Tsurumi, Walden, Chester, and Cummings each describe critical component technologies of the software radio. There are numerous others, such as multithreadedmultiprocessing,open architecture standards, and smart antennas thatwill also shape the productization of the software radio. These are to be covered in the software and DSP Feature Series. In addition, we did not have sufficient space in this Feature Topic to address software implementation issues in depth. Instead,we have included an introductory software architecture article , “Complexity of a Software GSM Base Station,” by Dr. Thierry Turletti. This article characterizes the computationaldemandsof asoftwarebase station based in part on his implementation of one while on a post-doctoral fellowship at the Massachusetts Institute of Technology. This article lays essential groundwork for more detailed implementation issuesto be addressed in the Feature Serieslater this year. The Feature Topicconcludeswith a surveyarticle that stressescommercialization in the marketplace, “Software Radio Technology: AEuropeanPerspective” by Dr Walter H. W. Tuttlebee. This article outlines European research and development in softwareradios, including military roots and the role of this technology in defining 3G waveforms and air interfaces. Dr. Tuttlebee characterizes essential differences in the U.S. and European motivations for software radio. To paraphrase, North America needs multimode handsets for roaming, which is a given in Europe. Europe, on the other hand, needs multimode handsets and infrastructure for incremental (and cost-effective) deployment of wideband CDMA, the 3G technology of the Universal Mobile TelecommunicationsService (UMTS). The story obviously does not end here. The Feature Series will include the following articles that build on the foundation laid in this Feature Topic. “Open Architecture Standards for the Software Radio,” by Mark Cummings, Technical Chair of the SDR Forum and Steve Heath of Motorola, United Kingdom, defines an architecture framework for the software radio. The Forum is the global leader in software radio standardization. One current thrust of the Forum is software download. After a brief review of the SDR Forum reference model, this artick describes the application programmer interface (API) for software that is downloadable to a software radio over the air. Service providers view this technology as essential to service differentiation and to keeping the costs of the 3G rollout low. Dr. Chris Dick of Xilinx and Fred Harris of the Cubic Corp describe limited precision arithmetic filters, computationally efficient coordinate rotation, and dynamically reconfigurable software radio functions using FPGAs. Their article, “Configurable Logic for Digital Communications: Some Signal Processing Perspectives,” extends the ideas introduced in the present Feature Topic. “Recent Developments in Enabling Technologies for the Software-Defined Radio” was submitted by DimitriosEfstathiou,Jose Fridman, and Zoran Zvonar of Analog Devices Inc. Their original article is being restructured into two for the Feature Series. One contribution provides a comprehensive update on DSP technology of major commercial DSP systems. The other describes software radio base stations
IEEE Communications Magazine
February 1999
for CDMA, including despreader software and performance. The pragmatics of implementing software base stations are addressedfurther in Dr. Rob Shepherd’s article “Software Streaming in SoftwareRadio Architectures.” Rob is from Cambridge Consultants, LTD of the United Kingdom, a developer of real-time software for embedded applications. This article provides practical insights into the integration of software radio functions in a UNIX-like environment. An economically important application of software radios is the smart antenna for 3G infrastructure. “SoftwareAntennas in Asia” by Ryuji Kohno of Yokahama National University, Japan, summarizes the theory and practice of smart antenna technology in Japan. Finally, the editorial board would like thank Andrzej Jajszczyk for his persistence in coaxing us to make the time necessary to bring this Feature Topic to the members of the Communications Society. We hope this Feature Topic whets your appetite for the additionalcontributionsplanned for the Feature Series.
BIOGRAPHIES JOSEPH MITOLA111 (
[email protected]) is a consulting scientist with the MITRE Corporation. He is presently on loan t o the US. Department of Defense where he
manages radio programs for the Defense Advanced Research Projects Agency (DARPA). Previously, he was chief scientist of electronic systems with E-Systems (now Raytheon). He has also held similar positions with ITT, Harris Corporation, and Advanced Decision Systems. He has a B.S.E.E. from Northeastern University and an M.S.E. from Johns Hopkins University. He has published dozens of technical papers and lecture notes on software radio, and is credited with first publishing the concept of the canonical software radio in 1992. DAVIDB. CHESTER [MI (
[email protected]) is responsible for strategic technology development within Harris Semiconductor’s Communications Products Business Unit. He has been involved in the definition, development, and analysis of software radio architectures and components for over 15 years. Prior to joining Harris Semiconductor in 1990, he was a communication systems engineer at Harris‘ Electronic Systems Sector. He received his B.S. degree in physics from Xavier University in 1977, and his M.S.E.E. and Ph.D. degrees from the University of Cincinnati in 1979 and 1982. He is a member of the graduate faculty at Florida Tech and is Harris Semiconductor liaison to the University of Central Florida, the University of Florida, and the University of South Florida. Shinichiro Haruyama is a researcher at Advanced Telecommunication Laboratory of SONY Computer Science Laboratories, Tokyo, Japan. He i s also an assistant professor at Keio University, Yokohama, Japan. He received an M.S. in engineering science from University of California at Berkeley and a Ph.D. in computer science from the University of Texas at Austin. He has worked at Bell Laboratories of Lucent Technologies, U.S.A. before joining Keio University in 1997. He joined SONY Computer Science Laboratories, Inc. in Tokyo, Japan in 1998. His research interests include software radio, wireless communication, reconfigurable system, FPGA, and VLSl design automation. THIERRYT U R L E(
[email protected]) ~I is a research scientist in the High-speed Networking Research Group at INRIA Sophia Antipolis, France. His current interests include distribution of multimedia flows over heterogeneous receivers, and software radio applications. He was a postdoctoral associate in the Telemedia, Networks and Systems Group at the MIT Laborat o r y f o r Computer Science from September 1995 t o September 1996. He has worked on the Spectrumware project headed by David Tennenhouse. He has designed and implemented in software part of a GSM base station which is currently integrated into the VuSystem. His previous research, done in particular with J-C. Bolot and C. Huitema within the MICE and MERCI European projects, were focused on designing, implementing, and evaluating multimedia applications over the Internet. Specifically, he developed IVS, one of the first videoconferencing applications for the Internet.
WALTER TUTLEBEE[SM] (
[email protected]) is business development manager for radio communications at Roke Manor Research, a SIEMENS R&D company based in the United Kingdom (www.roke.co.uk). Walter holds B.Sc., M.B.A., and Ph.D. degrees from Southampton and Cranfield Universities, United Kingdom. He has been involved in personal communications since the mid-1980s. initially as a research engineer, and subsequently assuming project and area responsibility for a range of personal communications standardization and development activities i n DECT, GSM, and UMTS. In recent years he has broadened his role t o one of monitoring and predicting technology and market developments in order t o create and steer new R&D initiatives within his company. As such he has pioneered Roke Manor‘s software radio initiatives in personal communications, becoming recognized as a leading European exponent of software radio.
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