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Suppressing the Effects of Aliasing and IQ Imbalance on Multiband Spectrum Sensing

Eyosias Yoseph Imana; Taeyoung Yang; Jeffrey H. Reed
Journal PaperIEEE Transactions on Vehicular Technology; Volume: 66, Issue: 2, Feb. 2017


In cognitive radio networks, secondary users (SUs) can use a frequency band when the primary user (PU) of the band is not transmitting. Spectrum sensing is one of the methods that SUs employ to know if the PU has stopped transmitting. Accurate spectrum sensing boosts the likelihood that an SU detects a spectrum opportunity. However, it will be challenging for affordable receivers to support accurate spectrum sensing due to receiver impairments, including IQ imbalance and aliasing. Several other papers have developed methods that can address the effects of IQ imbalance in spectrum sensing. This paper presents a technique that can address not only IQ imbalance but the effects of aliasing on multiband spectrum sensing as well. We use channelized spectrum-domain modeling of receivers to develop the technique. This paper presents the theoretical development of the receiver modeling technique and the proposed spectrum sensing mechanism. The performance of the proposed mechanism is evaluated using simulations and hardware-based measurements. The results demonstrate that the proposed mechanism significantly enhances the opportunity detection probability of affordable cognitive radios with high IQ imbalance and poor antialiasing filter selectivity performances.

FSK-Based Reactive Jammer Piggybacking

Marc Lichtman, T. Charles Clancy, Jeffrey H. Reed
Journal PaperIEEE Communications Letters, vol. 21, no. 1, pp. 68-71, Jan. 2017


The complexity and sophistication of communications jamming will continue to increase over time. The traditional approach to jammer mitigation is to harden radios, often sacrificing communications performance for more advanced jamming protection. To provide an escape from this trend, we propose a jammer exploitation strategy in which the communications system causes an enemy reactive jammer to act as an unwitting relay. This can lead to an improvement in communications as a result of the jamming attack itself. The strategy proposed in this letter revolves around using a frequency-shift keying waveform that is tuned in such a way to exploit the jammer's behavior. We derive the channel capacity when using the waveform along with practical coding, and provide numerical results to gain insight.

Enhancing the robustness of LTE systems: analysis and evolution of the cell selection process

J. H. Reed, M. Labib, V. Marojevic, and A. I. Zaghloul
Journal Paper IEEE Communications Magazine, vol. 55, no. 2, pp. 208-215, February 2017


The commercial success of LTE makes it the primary standard for 4G cellular technology, and its evolution paves the path for 5G technology. Furthermore, LTE Unlicensed has been proposed recently to allow cellular network operators to offload some of their data traffic to LTE component carriers operating in the unlicensed band. Hence, it is critical to ensure that the LTE system performs effectively even in harsh signaling environments in both licensed and unlicensed spectrum. This article analyzes the effect of different levels of RF spoofing applied to LTE. RF spoofing affects LTE devices during the initial cell selection process, where a strong nearby cell can impede access to a serving LTE network. This is a serious threat and can be caused unintentionally, in the case of dense and uncoordinated LTE deployment in unlicensed spectrum, or intentionally, where an adversary sets up a fake LTE cell in either licensed or unlicensed LTE spectrum. This article analyzes and experimentally demonstrates the severity of these threats for the evolution of LTE and proposes effective mitigation techniques to prevent denial of service. These mitigation techniques improve the cell selection process at the LTE user equipment, and are backward-compatible with existing LTE networks. We recommend that these modifications be enforced in future releases for increasing the availability and scalability of LTE.

Coexistence Between Wi-Fi and LTE on Unlicensed Spectrum: A Human-Centric Approach

Xu Yuan; Xiaoqi Qin; Feng Tian; Y. Thomas Hou; Wenjing Lou; Scott F. Midkiff;Jeffrey H. Reed
Journal PaperIEEE Journal on Selected Areas in Communications, vol. 35, no. 4, pp. 964-977, April 2017


In recent years, there has been great interest from the cellular service providers to use the unlicensed spectrum for their service offerings. On the other hand, existing unlicensed users in these bands (e.g., Wi-Fi in the 5-GHz band) have serious concern that such coexistence will jeopardize their service quality. Although there are some proposals on how to achieve coexistence, they are driven by the service providers and as such there remain many issues and skepticism. In this paper, we take a novel human-centric approach to understand coexistence between Wi-Fi and LTE by focusing on human satisfaction. Through mathematical modeling, problem formulation, and extensive simulations studies, we show that in terms of maximizing total human satisfaction function, there does not appear to be any advantage with the coexistence of unlicensed spectrum for Wi-Fi and LTE under static partitioning of unlicensed spectrum. This finding serves as a powerful counter argument to some LTE service providers’ proposal to share the unlicensed spectrum with Wi-Fi through static partitioning. On the other hand, we find that there is a significant improvement in human satisfaction in coexistence between Wi-Fi and LTE under adaptive spectrum partitioning. Since adaptive spectrum partitioning may require a user to change its service provider whenever there is a change among the users, we propose a practical (semi-adaptive) algorithm for implementation without affecting existing users’ service providers. Through performance evaluation, we show that the proposed semi-adaptive algorithm is highly competitive.

Dynamic sounding for multi-user MIMO in wireless LANs

Xiaofu Ma; Qinghai Gao; Ji Wang; Vuk Marojevic; Jeffrey H. Reed
Journal PaperIEEE Transactions on Consumer Electronics, vol. 63, no. 2, pp. 135-144, May 2017


Consumer electronic (CE) devices increasingly rely on wireless local area networks (WLANs). Next generation WLANs will continue to exploit multiple antenna systems to satisfy the growing need for WLAN system capacity. Multipleinput multiple-output (MIMO) antenna systems improve the spectral efficiency and single user throughput. Multi-user MIMO (MU-MIMO) systems exploit the spatial separation of users for increasing the sum-throughput. In an MU-MIMO system, efficient channel sounding is essential for achieving optimal performance. The system analysis in this paper provides insights into the rate at which to perform channel sounding. This paper shows that optimal sounding intervals exist for single user transmit beamforming (SU-TxBF) and MU-MIMO, and proposes a low-complexity dynamic sounding approach for practical MUMIMO WLAN deployments. The proposed approach adjusts the sounding interval adaptively based on the real-time learning outcomes in the given radio environment. Using real over-the-air channel measurements, significant throughput improvements (up to 31.8%) are demonstrated by adopting the proposed dynamic sounding approach, which is compliant with IEEE 802.11ac1.


Beyond Overlay: Reaping Mutual Benefits for Primary and Secondary Networks Through Node-Level Cooperation

J. H. Reed, Xu Yuan, Yi Shi, Xiaoqi Qin, Y Thomas Hou, Wenjing Lou, Sastry Kompella, Scott F Midkiff
Journal PaperIEEE Transactions on Mobile Computing, vol. 16, no. 1, pp. 2-15, Jan. 1 2017. doi: 10.1109/TMC.2016.2539161


Existing spectrum sharing paradigms have set clear boundaries between the primary and secondary networks. There is either no or very limited node-level cooperation between the primary and secondary networks. In this paper, we develop a new and bold spectrum-sharing paradigm beyond the state of the art for future wireless networks. We explore network cooperation as a new dimension for spectrum sharing between the primary and secondary users. Such network cooperation can be defined as a set of policies under which different degrees of cooperation are to be achieved. The benefits of this paradigm are numerous, as they allow integrating resources from two networks. There are many possible node-level cooperation policies that one can employ under this paradigm. For the purpose of performance study, we consider a specific policy called United cooperation of Primary and Secondary (UPS) networks. UPS allows a complete cooperation between the primary and secondary networks at the node level to relay each other's traffic. As a case study, we consider a problem with the goal of supporting the rate requirement of the primary network traffic while maximizing the throughput of the secondary sessions. For this problem, we develop an optimization model and formulate a combinatorial optimization problem. We also develop an approximation solution based on a piece-wise linearization technique. Simulation results show that UPS offers significantly better throughput performance than that under the interweave paradigm.

A communications jamming taxonomy

J. H. Reed, Marc Lichtman, Jeffrey D. Poston, SaiDhiraj Amuru, Chowdhury Shahriar, T. Charles Clancy, R. Michael Buehrer
Journal PaperIEEE Transactions on Mobile Computing, vol. 16, no. 1, pp. 2-15, Jan. 1 2017. doi: 10.1109/TMC.2016.2539161


With the now widespread availability of software-defined radio technology for wireless networks, the distinction between jamming in the original electronic warfare sense and wireless cybersecurity attacks becomes hazy. A taxonomy delineates these concepts in the rapidly expanding field of wireless security, classifying communication jammers' theoretical behaviors and characteristics.

An Introduction to Ultrawideband Communications Systems

J. H. Reed
BookPrentice Hall | 1 edition (March 23, 2012)| ISBN-10:0133038696, ISBN-13: 978-0133038699


Wideband book coverIntroduction to Ultra Wide Band Communication Systems offers a comprehensive view of UWB system design, that spans propagation, antennas, receive and transmitter implementations, standards and regulations, interference issues, simulation techniques, modulation and multiple access, network issues, and applications. This book encompasses all areas of design and implementation of UWB systems crucial to their successful testing and deployment. UWB offers unique capabilities, such as extremely high data rates, and building partitions and ground penetrating transmission. The FCC acknowledged the benefits of UWB when, in 2001, regulations were modified to allow the transmission of UWB signals. The standardization effort has recently come to fruition with the creation of a new, regulated communication standard. However, a new standard brings along with it new regulations and equipment; and the design of UWB systems is very different than traditional communication systems. The current general reference books for design of communication systems are insufficient, and in some cases could be misleading to a UWB designer. Furthermore, there is a tremendous need to unify the diverse concepts and fields of study embedded in the design of UWB systems. Source:

Software Radio: A Modern Approach to Radio Engineering

J. H. Reed
Book Prentice Hall | May 30, 2002 | ISBN-10: 0130811580 , ISBN-13:978-0130811585
software defined book cover

This is an excellent book for all RF and signal processing engineers building advanced wireless systems.

Software-based approaches enable engineers to build wireless system radios that are easier to manufacture, more flexible, and more cost-effective. Software Radio: A Modern Approach to Radio Engineering systematically reviews the techniques, challenges, and tradeoffs of DSP software radio design. Coverage includes constructing RF front-ends; using digital processing to overcome RF design problems; direct digital synthesis of modulated waveforms; A/D and D/A conversions; smart antennas; object-oriented software design; and choosing among DSP microprocessors, FPGAs, and ASICs. Source:

Radio Resource Management in Cellular Systems (The Springer International Series in Engineering and Computer Science

J. H. Reed, Nishith D. Tripathi, Hugh F. Van Landingham; Springer; 2001 edition
Book ISBN:978-1-4419-4897-7

Resource ManagementRadio Resource Management in Cellular Systems is the first book to address the critical issue of radio resource management in emerging (i.e., third generation and beyond) wireless systems. This book presents novel approaches for the design of high performance handoff algorithms that exploit attractive features of several existing algorithms, provide adaptation to dynamic cellular environment, and allow systematic tradeoffs among different system characteristics. Efficient handoff algorithms cost-effectively enhance the capacity and quality of service (QoS) of cellular systems. A comprehensive foundation of handoff and related issues of cellular communications is given. Tutorial-type material on the general features of 3G and 3.5G wireless systems (including CDMA2000, UMTS, and 1xEV-DO) is provided. Key elements for the development of simulators to study handoff and overall RF performance of the integrated voice and data cellular systems (including those based on CDMA) are also described.

Finally, the powerful design tools of neural networks and fuzzy logic are applied to wireless communications, so that the generic algorithm approaches proposed in the book can be applied to many other design and development areas. The simulation models described in the book represent a single source that provides information for the performance evaluation of systems from handoff and resource management perspectives. Radio Resource Management in Cellular Systems will prove a valuable resource for system designers and practicing engineers working on design and development of third generation (and beyond) wireless systems. It may also be used as a text for advanced-level courses in wireless communications and neural networks. Source:

The Software Testing in the Cloud: Perspectives on an Emerging Discipline

Jeff Reed, Hamilton Turner, Jules White, José Galindo, Adam Porter, Madhav Marathe, Anil Vullikanti, Aniruddha Gokhale (382-403)
Book Chapter IGI Global , November 2012 | ISBN-10:1466625368; ISBN-13:9781466625365
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In recent years, cloud computing has gained a significant amount of attention by providing more flexible ways to store applications remotely. With software testing continuing to be an important part of the software engineering life cycle, the emergence of software testing in the cloud has the potential to change the way software testing is performed. Software Testing in the Cloud: Perspectives on an Emerging Discipline is a comprehensive collection of research by leading experts in the field providing an overview of cloud computing and current issues in software testing and system migration. Deserving the attention of researchers, practitioners, and managers, this book aims to raise awareness about this new field of study. Source: IGI Global

Green Communications: Realizing Environmentally Friendly, Cost Effective, and Energy Efficient Wireless Systems

Jeff Reed, H. I. Volos, D. Datla, X. Chen, A. He, A. Amanna, T. R. Newman, S.M. Shajedul Hasan and T. Bose
Book Chapter Energy-Aware Systems and Networking for Sustainable Initiatives; IGI Global , November 2014 | page(s): 22; ISBN-10:1466625368; DOI:10.4018/978-1-4666-4852-4.ch028
book cover

The exponential growth of wireless systems makes their carbon footprint hard to ignore. This chapter presents statistics related to the energy consumption of cellular networks' infrastructure in order to motivate the need for more efficient and environmentally friendly communications. A definition of the term “Green Communications” is provided along with different metrics that can be used to quantify energy efficiency for the various aspects of wireless infrastructure. In addition to topics related to cellular infrastructure, the chapter presents a brief review of key techniques that can be potentially used for improving energy efficiency. Furthermore, since improving energy efficiency is not by itself sufficient for low-carbon systems, possible ways of using and managing energy harvested from renewable sources such as solar and ambient RF signals are discussed. Moreover, the concept of Wireless Distributed Computing is introduced to illustrate how a group of wireless devices can share their resources for achieving a set of common goals. Finally, resource allocation is examined for managing the trade-offs involved when simultaneously minimizing the carbon footprint and performing the necessary communication and computation tasks in mobile devices. Source: IGI Global

Encyclopedia of Electrical and Electronics Engineering

J. H. Reed, P. Petrus and H. F. VanLandingham
Book Chapter"Co-channel Interference in Wireless Communication Systems"; John Wiley & Sons, Inc., February 1999 (invited paper) ISBN-10:9780471346081;

book cover The Wiley Encyclopedia of Electrical and Electronics Engineering is a unique, comprehensive reference work that defines the entire discipline, bringing together the core knowledge from every one of the many specialties encompassed by electrical and electronics engineering. It is the ideal starting point for research projects, whether addressing basic questions in power systems and communications, or learning advanced applications in neural networks and robotics. In addition to electrical and electronics engineering applications, the Encyclopedia features important topics of interest to engineers, including: education; historical background of fields in electrical and electronics engineering; patents; technology and society; and computer and software engineering. Updated quarterly, this comprehensive reference work keeps pace with advances across the entire field of Electrical and Electronics Engineering. Source: John Wiley & Sons

Neuro-Fuzzy and Fuzzy-Neural Applications in Telecommunications (Signals and Communication Technology)

P. Stavroulakis, N. D. tripathi, J. H. Reed, and H. F. VanLandingham
Book ChapterApplication of a Neurofuzzy System to Handoffs in Cellular Communications; Springer Publishing, May 2004 , pp. 22; ISBN-10:3540332863; ISBN-13:978-1567203110
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For the first time, this highly interdisciplinary book covers the applications of neuro-fuzzy and fuzzy-neural scientific tools in a very wide area within the communications field. It deals with the important and modern areas of telecommunications amenable to such a treatment. Source:

Cognitive Radio Technology, Second Edition

Bruce Fette, Y. Zhao, S. Mao, J. Neel, and J.H. Reed
Book Chapter The Radio Environmnet Map, November 2009; ISBN-10:0123745357; ISBN-13:978-0123745354
book cover

This book gives a thorough knowledge of cognitive radio concepts, principles, standards, spectrum policy issues and product implementation details. In addition to 16 chapters covering all the basics of cognitive radio, this new edition has eight brand-new chapters covering cognitive radio in multiple antenna systems, policy language and policy engine, spectrum sensing, rendezvous techniques, spectrum consumption models, protocols for adaptation, cognitive networking, and information on the latest standards, making it an indispensable resource for the RF and wireless engineer. The new edition of this cutting edge reference, which gives a thorough knowledge of principles, implementation details, standards, policy issues in one volume, enables the RF and wireless engineer to master and apply today's cognitive radio technologies. Source:

Encyclopedia of RF and Microwave Engineering

Jeff Reed,R. M. Buehrer and B. M. Donlan
Book Chapter "Ultra-wideband Wireless Systems", John Wiley & sons; November 2005; pp. 5411-5423, ISBN-10:471-27053-9; ISBN-13:978-0123745354
book cover

RF and Microwave Engineering is one of the fastest growth areas of the past decade and will probably continue to be a very active area of research and application in a large variety of fields. The six volume set of Encyclopedia of RF and Microwave Engineering illustrates how this field has been the key to enabling technology responsible for the phenomenal growth of wireless communications. This set also examines how RF and microwave engineering continues to have great influence as the technology behind such important applications as radar, remote sensing, remote control, sensors, navigation, surveillance, electronic warfare, radiometers, plasma research, and imaging. Source: John Wiley & Sons

Wireless Personal Communications: Research Developments

Jeff ReedJ. D. Laster
Book Chapter "A Survey of Adaptive Single Channel Interference Rejection Techniques for Wireless Communications", Kluwer Press; 1994; pp.29-54 ISBN-13:978-1-4757-2368-7
book cover

The area of personal and wireless communications is a burgeoning field. Technology advances and new frequency allocations for personal communication services (PCS) are creating numerous business and technical opportunities. It is becoming clear that an essential requirement for exploiting opportunities is the ability to track the dramatic changes in wireless technology, which is a principal aim of this book. Wireless Personal Communications: Research Developments places particular emphasis on the areas of signal processing, propagation and spread-spectrum, and emerging communication systems. This book contains new results on adaptive antennas for capacity improvements in wireless communication systems, as well as state-of-the-art information on the latest technical developments. Also included are several chapters which discuss the impact of defense conversion on the wireless industry, and related competitive issues. The six parts of the book each focus on a distinct issue in wireless communications. Part I contains several tutorial chapters on key areas in wireless communications. The first chapter is on radio wave propagation for emerging wireless personal communication systems. Chapter two contains a comprehensive study of emerging DSP-based interference rejection techniques for single channel (antenna) systems. Chapter three deals with spread spectrum wireless communications, explaining the concept of spread spectrum, modeling techniques for spread spectrum, and current applications and research issues for spread spectrum systems. Part II focuses on digital signal processing and spread spectrum, two means of creating interference and multipath robust communications. Part III concerns propagation aspects of wireless communications. Part IV discusses the performance of emerging wireless systems. Part V describes the opportunities and pitfalls of defense conversion from the perspective of several U.S. defense firms that have successfully made the transition to commercial wireless. The final section discusses a number of competitive issues regarding personal communication services. Source: Springer Press

Wireless Personal Communications: The Evolution of PCS

Jeffrey H. Reed, N. R. Mangalvedhe
Book Kluwer | 1996 | ISBN - 13: 978-1461285724; ISBN-10:1461285720
Wireless Personal Communications book cover

"Wireless personal communications, or wireless as it is now being called, has arrived. The hype is starting to fade, and the hard work of deploying new systems and services for personal communications is underway. In the United States, the FCC propelled the wireless era from infancy to mainstream with a $7.7 billion auction of 60 MHz of radio spectrum in the 180011900 MHz band. With the largest single sale of public property in the history of mankind mostly complete, the resources of the entire world are being called upon to develop inexpensive, rapidly deployable wireless systems and sub­ scriber units for an industry that is adding subscribers at greater than 50% annual rate. This growth is commonplace for wireless service companies throughout the world, and in the U.S., where as many as 7 licensed wireless service providers may be competing for cellularfPCS customers within the next couple of years, differentiators in cost, qual­ ity, service, and coverage will become critical to customer acceptance and use. Many of these issues are discussed in the papers included in this book." Source:

Cellular Communications: A Comprehensive and Practical Guide

Jeffrey H. Reed, Nishith D. Tripathi
Book IEEE Press | John Wiley & Sons| August, 2014 | ISBN - 13: 978-0-470-472071; ISBN-10: 0470472073
Cellualar Communications book cover

"Even as newer cellular technologies and standards emerge, many of the fundamental principles and the components of the cellular network remain the same. Presenting a simple yet comprehensive view of cellular communications technologies, Cellular Communications provides an end-to-end perspective of cellular operations, ranging from physical layer details to call set-up and from the radio network to the core network. This self-contained source for practitioners and students represents a comprehensive survey of the fundamentals of cellular communications and the landscape of commercially deployed 2G and 3G technologies and provides a glimpse of emerging 4G technologies." Source:

Open Source Software-defined Radio Tools for Education, Research, and Rapid Prototyping

Jeffrey H. Reed, Jason Snyder, Deepan Seeralan, Shereef Sayed, Jeffery Wilson, Carl B. Dietrich, Stephen H. Edwards
Journal PaperInternational Journal on Software Tools for Technology Transfer, Springer, June 2012


This article describes the Open Source SCA Implementation::Embedded project, an open source software development kit designed for rapid prototyping of software defined radios consistent with the software communications architecture. The SCA is a product of the American military's SDR acquisition program and has played a large role in SDR development in the military and in the wireless industry. OSSIE was designed for use in wireless communications curricula and research efforts, so it is easy to learn and illustrative of software engineering, programming, and communications engineering concepts important in industrial practice today. OSSIE includes a core framework (i.e., common services enumerated in the SCA). It also includes graphical user interface-oriented tools that are easily learned and free to download and use. The tools auto-generate SCA-specific component source code and supporting files, leaving the developer to provide signal processing functionality. In addition, visualization tools for debugging and a growing library of SDR software components are available. Discussed herein are examples of SDRs designed using OSSIE, including embedded applications. OSSIE enables easy transition from concepts to practice in SDR design for communications engineers who may not have a strong software background.

Hybrid Experiential-Heuristic Cognitive Radio Engine Architecture and Implementation

Jeffrey H. Reed, Ashwin Amanna, Daniel Ali, David Gonzalez Fitch,
Journal PaperJournal of Computer Networks and Communications, vol. 2012, Article ID 549106, 15 pages, 2012


The concept of cognitive radio (CR) focuses on devices that can sense their environment, adapt configuration parameters, and learn from past behaviors. Architectures tend towards simplified decision-making algorithms inspired by human cognition. Initial works defined cognitive engines (CEs) founded on heuristics, such as genetic algorithms (GAs), and case-based reasoning (CBR) experiential learning algorithms. This hybrid architecture enables both long-term learning, faster decisions based on past experience, and capability to still adapt to new environments. This paper details an autonomous implementation of a hybrid CBR-GA CE architecture on a universal serial radio peripheral (USRP) software-defined radio focused on link adaptation. Details include overall process flow, case base structure/retrieval method, estimation approach within the GA, and hardware-software lessons learned. Unique solutions to realizing the concept include mechanisms for combining vector distance and past fitness into an aggregate quantification of similarity. Over-the-air performance under several interference conditions is measured using signal-to-noise ratio, packet error rate, spectral efficiency, and throughput as observable metrics. Results indicate that the CE is successfully able to autonomously change transmit power, modulation/coding, and packet size to maintain the link while a non-cognitive approach loses connectivity. Solutions to existing shortcomings are proposed for improving case-base searching and performance estimation methods.

Parametric optimization of software defined radio configurations using design of experiments

Jeffrey H. Reed, Ashwin Amanna, Daniel Ali, David Gonzalez Fitch,
Journal PaperAnalog Integrated Circuits and Signal Processing 73, no. 2 (2012): 637-648. 1.


Cognitive radio (CR) systems incorporate learning and decision making into wireless and networking systems with the goal of improving performance and interoperability. Research has focused on artificial intelligence control and optimization of radio input parameters with little attention placed on identifying initialization parameters of cognitive engines or on testing methods. While CR techniques continue to advance, calibration and testing remain largely stagnant with reliance on ad hoc and highly application specific approaches. Given that cognitive radio will be deployed in a variety of environments with each requiring unique calibration, systematic procedures are needed. An approach founded in design of experiments provides a purposeful framework for performing testing and identification of initialization parameters with an efficient number of test cases. Response surface methodology designs identify representative knowledge of system performance including input parameter significance and quadratic estimation models of output metrics. An example of calibrating transmit-and-receive gain settings on a software-defined radio illustrates the use of the framework

Spectrum Access Technologies: The Past, the Present, and the Future

Jeffrey H. Reed, Bernhard, J. T.; Park, J.-M.,
Journal PaperProceedings of the IEEE , vol.100, no. Special Centennial Issue, pp.1676-1684, May 2012, (invited paper)


This paper provides an overview of how our access to the electromagnetic spectrum has evolved and will continue to expand over time. We first focus on the historical origins of technological and regulatory choices, and provide some insight into how these choices have impacted the efficiency with which we currently utilize the spectrum, and how we can better use it in the future. In turn, we summarize the relevant technologies being discussed in today’s standardization and research and development efforts. Finally, we provide a vision for the evolution of spectrum access technologies that, intertwined with progressive regulatory and economic policies, will enable flexible and secure sharing of spectrum to deliver seamless mobility with ubiquitous service for users worldwide.

Closed-Loop Transmit Diversity Techniques for Small Wireless Terminals and Their Performance Assessment in a Flat Fading Channel

Jeffrey H. Reed, Raqibul Mostafa, Ramesh C. Pallat, Uwe Ringel, Ashok Arman Tikku
Journal PaperETRI Journal, vol.34, no.3, June 2012, pp.319-329.


Closed-loop transmit diversity is considered an important technique for improving the link budget in the third generation and future wireless communication standards. This paper proposes several transmit diversity algorithms suitable for small wireless terminals and presents performance assessment in terms of average signal-to-noise ratio (SNR) and outage improvement, convergence, and complexity of operations. The algorithms presented herein are verified using data from measured indoor channels with variable antenna spacing and the results explained using measured radiation patterns for a two-element array. It is shown that for a two-element array, the best among the proposed techniques provides SNR improvement of about 3 dB in a tightly spaced array (inter-element spacing of 0.1 wavelength at 2 GHz) typical of small wireless devices. Additionally, these techniques are shown to perform significantly better than a single antenna device in an indoor channel considering realistic values of latency and propagation errors.

Efficient detection of primary users in cognitive radio networks

Jeffrey H. Reed, Xuetao Chen, Tamal Bose, S.M. Hasan
Journal PaperJournal International Journal of Communication Networks and Distributed Systems, Publisher Interscience Enterprises Ltd, Issue Volume 8, Number 3–4/2012, Pages 267-285.


This paper proposes an approach to detect the primary user during the communication of the secondary users, using the concept of interference detection in the presence of a desired signal. The detection problem is first formulated as a multi–class classification problem. The pattern with medium bit error rate (BER) and low interference to signal power ratio (ISR) is identified as the most difficult case. A classifier based on a support vector machine (SVM) is proposed to solve this problem.

Cognitive radio engine parametric optimization utilizing Taguchi analysiss

Jeffrey H. Reed, Ashwin E Amanna, Daniel Ali, Manik Gadhiok, Matthew Price
Journal PaperEURASIP Journal on Wireless Communications and Networking 2012, 2012:5


Cognitive radio (CR) engines often contain multiple system parameters that require careful tuning to obtain favorable overall performance. This aspect is a crucial element in the design cycle yet is often addressed with ad hoc methods. Efficient methodologies are required in order to make the best use of limited manpower, resources, and time. Statistical methods for approaching parameter tuning exist that provide formalized processes to avoid inefficient ad hoc methods. These methods also apply toward overall system performance testing. This article explores the use of the Taguchi method and orthogonal testing arrays as a tool for identifying favorable genetic algorithm (GA) parameter settings utilized within a hybrid case base reasoning/genetic algorithm CR engine realized in simulation. This method utilizes a small number of test cases compared to traditional design of experiments that rely on full factorial combinations of system parameters. Background on the Taguchi method, its drawbacks and limitations, past efforts in GA parameter tuning, and the use of GA within CR are overviewed. Multiple CR metrics are aggregated into a single figure-of-merit for quantification of performance. Desirability functions are utilized as a tool for identifying ideal settings from multiple responses. Kiviat graphs visualize overall CR performance. The Taguchi method analysis yields a predicted best combination of GA parameters from nine test cases.

Opportunistic channel allocation decision making in cognitive radio communications

Jeffrey H. Reed, Shatila, H., Khedr, M.
Journal PaperInt. J. Commun. Syst.. April 2012. DOI: 10.1002/dac.2350


The global spread of wireless devices with mobile Internet access and the increasing demand of multimedia-based applications are fueling the need for wireless broadband networks. IEEE 802.16 and 802.20 are standards for a broadband wireless access with promising cognitive radio features to support mobile Internet access. However, because of the fast changing radio environment and the demand for dynamic spectrum allocation mechanisms, these standards must continuously readjust different radio parameters. The cognitive radio makes decisions based on its built-in inference engine, which also in time can adapt itself to different situations through the process of learning from experience. In this paper we present an automated opportunistic decision making and learning process for cognitive radio based on uncertainty reasoning algorithms. This novel approach is well suited in fast changing wireless environments with vague, incomplete, and heterogeneous information. Theory and simulations prove that decision making and learning of the cognitive radio based on the proposed approach cope with the changes in the radio environment. In this work we use fuzzy logic for the learning and decision making of the cognitive radio. Simulation also show that our approach provides accurate and precise decisions on allocating spectrum to mobile Internet users even in fast varying radio conditions. Copyright © 2012 John Wiley & Sons, Ltd.

Wireless distributed computing: a survey of research challenges

Jeffrey H. Reed, Datla, D.; Chen, X.; Tsou, T.; Raghunandan, S.; Hasan, S.M.S.; Dietrich, C.B.; Bose, T.; Fette, B.; Kim, J.
Journal PaperCommunications Magazine, IEEE , vol.50, no.1, pp.144-152, January 2012


Recent advancements in radio technology provide great flexibility and enhanced capabilities in executing wireless services. One of these capabilities that can provide significant advantages over traditional approaches is the concept of collaborative computing in wireless networks. With collaborative radio nodes, multiple independent radio nodes operate together to form a wireless distributed computing (WDC) network with significantly increased performance, operating efficiency, and abilities over a single node. WDC exploits wireless connectivity to share processing- intensive tasks among multiple devices. The goals are to reduce per-node and network resource requirements, and enable complex applications not otherwise possible, e.g., image processing in a network of small form factor radio nodes. As discussed in this article, WDC research aims to quantify the benefits of distributed processing over local processing, extend traditional distributed computing (DC) approaches to allow operation in dynamic radio environments, and meet design and implementation challenges unique to WDC with the help of recently available enabling technologies, such as software radios and cognitive radios.

Antenna Design Strategy and Demonstration for Software-Defined Radio (SDR)

Jeffrey H. Reed, T. Yang, W. Davis, W. Stutzman, J. Nealy, D. Dietrich, S.M. Hasan
Journal PaperAnalog Integrated Circuits and Signal Processing: Volume 69, Issue 2 (2011), Page 161-171


Antennas are a key enabling technology for software-defined radio (SDR). Although software is extremely flexible, SDR’s potential is limited by antenna size and performance. In this paper, we review typical antenna miniaturization techniques and fundamental theories that limit antenna size and performance including operational bandwidth, gain (or range), and radiation pattern. Possible antenna design strategies are discussed to meet the desired specifications in SDR based on observations from the limit theories. The application of strategies to enable multiband (resonant), continuous multiband (frequency independent), and instantaneous, ultra-wideband antennas are discussed qualitatively. Advantages, disadvantages, and design trade-off strategies for different types of antennas are compared from a system-level perspective. A design example for a compact ultra-wideband (UWB) antenna is presented for a software-defined platform. The example involves a direct-conversion radio developed in Wireless@VT that uses a Motorola RFIC having a 100 MHz–6 GHz operational frequency range with a 9 kHz–20 MHz channel bandwidth. The example antenna covers frequencies from 450 MHz to 6 GHz instantaneously with approximately 5-dBi realized gain over a finite-size ground plane, including return loss and omni-directional coverage.

A sub-space method to detect multiple wireless microphone signals in TV band white space

Jeffrey H. Reed, Harpreet S. Dhillon, Jeong-O Jeong, Dinesh Datla, Michael Benonis, R. Michael Buehrer
Journal PaperAnalog Integrated Circuits and Signal Processing: Volume 69, Issue 2 (2011), Page 161-171


The main hurdle in the realization of dynamic spectrum access systems from the physical layer perspective is the reliable sensing of low power licensed users. One such scenario shows up in the unlicensed use of the TV bands where the TV band devices are required to sense extremely low power wireless microphones (WMs). The lack of technical standards among various wireless manufacturers and the resemblance of certain WM signals to narrow-band interference signals, such as spurious emissions, further aggravate the problem. Due to these uncertainties, it is extremely difficult to abstract the features of WM signals and hence develop robust sensing algorithms. To partly counter these challenges, we develop a two-stage sub-space algorithm that detects multiple narrow-band analog frequency-modulated signals generated by WMs.

Power fingerprinting in SDR integrity assessment for security and regulatory compliance

Jeffrey H. Reed, Carlos R. Aguayo González
Journal PaperAnalog Integrated Circuits and Signal Processing, Volume 69, Numbers 2-3 (2011), 307-327. (


Software-Defined Radio (SDR) provides a flexible platform that facilitates radio resource management and enables new technologies and applications. Unfortunately, their reliance on software implementations makes them vulnerable to malicious software attacks that could impact their spectral emissions and disclose sensitive information. It is of critical importance for the widespread deployment of SDR to develop technologies that enable effective integrity assessment of communications platforms and timely detection of malicious intrusions. We provide further evidence of the feasibility of a novel approach called Power Fingerprinting (PFP) that enables an effective mechanism to perform integrity assessment of SDR. PFP relies on an external monitor that captures fine-grained measurements of the processor’s power consumption and compares them against stored signatures from trusted software by applying pattern recognition and signal detection techniques. Because it is implemented by an external monitor, PFP causes minimal disruption on the target system and also provides the necessary isolation to protect against malicious attacks to the monitor itself. Fine-granularity measurements deliver improved visibility into the execution status and make the PFP monitor difficult to evade, while the reliance on anomaly detection from trusted references makes it effective against zero-day attacks. We present the results of different feasibility experiments that support the applicability of PFP to SDR integrity assessment. In the first experiment, a PFP monitor is able to effectively detect the execution of a tampered routine that misconfigures the operational mode of a PICDEM Z radio platform, affecting the resulting spectral emission. In a second experiment, our monitor effectively identifies when a transmission routine is modified, affecting encryption settings. We also present an approach to improve the performance of PFP by characterizing the way a specific platform consumes power. This platform characterization, which can be done using principal component analysis or linear discriminant analysis, allows a PFP monitor to work only on the features that carry the most information. As a result, the PFP monitor is able to detect execution deviations resulting from a difference of a single bit transition, the smallest possible disruption

Task allocation and scheduling in wireless distributed computing networks

Jeffrey H. Reed, Dinesh Datla, Haris I. Volos, S. M. Hasan, and Tamal Bose
Journal PaperAnalog Integrated Circuits and Signal Processing , Volume 69, Numbers 2-3 (2011), 341-353. (


Wireless distributed computing (WDC) is an enabling technology that allows radio nodes to cooperate in processing complex computational tasks of an application in a distributed manner. WDC research is being driven by the fact that mobile portable computing devices have limitations in executing complex mobile applications, mainly attributed to their limited resource and functionality. This article focuses on resource allocation in WDC networks, specifically on scheduling and task allocation. In WDC, it is important to schedule communications between the nodes in addition to the allocation of computational tasks to nodes. Communication scheduling and heterogeneity in the operating environment make the WDC resource allocation problem challenging to address. This article presents a task allocation and scheduling algorithm that optimizes both energy consumption and makespan in a heuristic manner. The proposed algorithm uses a comprehensive model of the energy consumption for the execution of tasks and communication between tasks assigned to different radio nodes. The algorithm is tested for three objectives, namely, minimization of makespan, minimization of energy consumption, and minimization of both makespan and energy consumption

Grey Systems Theory Applications to Wireless Communications

Jeffrey H. Reed, Amanna, K. Thamvichai, M. Carrick, AT. Bose
Journal PaperAnalog Integrated Circuits and Signal Processing: Volum 69, Issue 2 (2011), Page 259


This paper discusses grey systems theory (GST) applications in wireless communications and highlights its potential to cognitive radio. GST consists of information theory concepts and practical algorithms developed to address situations where information is incomplete and affected by random uncertainties. Two GST concepts, grey relational analysis (GRA) and grey model (GM) prediction theory are discussed. GRA provides a method to quantify the similarity between a reference data series and set of data while GM is used for modeling time series data and enables prediction of future values with limited data points and unknown probability distributions. These two techniques are surveyed with respect to their applications to wireless communications. Their application to predictive Cognitive Radio and as a similarity measure for case based reasoning cognitive engines is highlighted. A GRA based Automatic Modulation Classification (AMC) algorithm is applied to digital communications signals with preliminary results shown in simulation.

Green Communications: A New Paradigm for Power Efficient Wireless Systems

Jeffrey H. Reed,A. He, A. Amanna, T. Tsou, X. Chen. D. Datla, J. Gaeddert, T. Newman, S.M. Hasan, H. Volos
Journal PaperJournal of Communications Special Issue on Practical Physical Layer Techniques for 4G Systems & Beyond, Vol 6, No. 5. July 2011


Individual cognitive radio nodes in an ad-hoc cognitive radio network (CRN) have to perform complex data processing operations for several purposes, such as situational awareness and cognitive engine (CE) decision making. In an implementation point of view, each cognitive radio (CR) may not have the computational and power resources to perform these tasks by itself. In this paper, wireless distributed computing (WDC) is presented as a technology that enables multiple resource-constrained nodes to collaborate in computing complex tasks in a distributed manner. This approach has several benefits over the traditional approach of local computing, such as reduced energy and power consumption, reduced burden on the resources of individual nodes, and improved robustness. However, the benefits are negated by the communication overhead involved in WDC. This paper demonstrates the application of WDC to CRNs with the help of an example CE processing task. In addition, the paper analyzes the impact of the wireless environment on WDC scalability in homogeneous and heterogeneous environments. The paper also proposes a workload allocation scheme that utilizes a combination of stochastic optimization and decision-tree search approaches. The results show limitations in the scalability of WDC networks, mainly due to the communication overhead involved in sharing raw data pertaining to delegated computational tasks.

Designing and Deploying a Building-Wide Cognitive Radio Network Testbed

Jeffrey H. Reed, T. Newman, S.M. Hasan, D.Depoy, T. Bose
Journal PaperCommunications Magazine, IEEE , vol.48, no.9, pp.106,112, Sept. 2010 doi: 10.1109/MCOM.2010.5560594


Wireless communication technology is constantly advancing with the primary objective being to improve the quality of service for the end user. Cognitive radio is a technology capable of advancing wireless communications to the next generation of intelligent devices. Integrating cognition into wireless applications such as dynamic spectrum access, radio resource management, wireless distributed computing, and even traditional protocol stacks has already been shown to provide benefits related to the communications quality of service. The majority of cognitive radio related research has been limited to theoretical frameworks and simulations or in a few cases, demonstrating prototype DSA devices on a small scale. In order to continue advancing in this area, larger-scale experiments that are reproducible and able to be moved beyond theoretical simulations are required. Virginia Tech has built a testbed for software-defined and cognitive radio related research for the purpose of rapid next-generation communication system prototyping using a medium scale size network of flexible wireless nodes. In this article we present the details of the development, design decision rationale, and deployment of this testbed in hopes that it will be both used by the research community, and duplicated and improved in order to further the development of the many different facets of cognitive radio research.

Wireless Distributed Computing in Cognitive Radio Networks, Ad-Hoc Network

Jeffrey H. Reed, D. Datla, H.I. Volos, S.M. Hasan, and Tamal Bose
Journal PaperJournal of Communications, Ad Hoc Networks, Special Issue on Practical Physical Layer Techniques for 4G Systems & Beyond, Vol 6, No. 5. July 2011


Telecommunication usage has skyrocketed in recent years and will continue to grow as developing world reaches to wireless as the communication medium of choice. The telecommunications world is only now addressing the significant environmental impact it is creating as well as the incredible cost on power usage. This realization has led to a push towards Green Communications that strives for improving energy efficiency as well as energy independence of telecommunications.

Energy consumption minimization for mobile and wireless devices - a cognitive approach

Jeffrey H. Reed, A. He, S. Srikantesware, K.K. Bae, T.R. Newman, W. Tranter, M. Verhelst
Journal PaperConsumer Electronics, IEEE Transactions on , vol.56, no.3, pp.1814,1821, Aug. 2010 doi: 10.1109/TCE.2010.5606331


Energy consumption for mobile and wireless communication device, such as cell phones, has long been an important aspect for both designers and customers. This paper shows how a cognitive radio (CR) framework can help to reduce system energy consumption of a mobile and wireless communication device based on the application quality of service requirement, the channel condition, and the radio capabilities and characteristics. The CR framework enables not only adaptation of modulation, coding rate, coding gain, and radiated power as conventional adaptive modulation (AM) scheme, but also joint adjustment of radio component characteristics (e.g., power amplifier (PA) characteristics) to achieve high energy efficiency. A unified PA efficiency model characterizing theoretical Class A, Class B, and practical PAs is adopted and enables the analysis of the impact of different radio configurations and channel conditions on energy efficiency. Significant energy savings (up to 90%) using the proposed CR framework for systems with theoretical PAs and with a realistic PA can be achieved compared with the conventional AM approach in simulation. This framework can also be used to manage other radio resources.

Railway Cognitive Radio

Jeffrey H. Reed, A. Amanna, M. Ghadiok, M. Price
Journal PaperVehicular Technology Magazine, IEEE , vol.5, no.3, pp.82,89, Sept. 2010 doi: 10.1109/MVT.2010.938275


Wireless communication plays a vital role in the success of railroad operations. This article describes an effort toward developing a railroad-specific cognitive radio (rail-CR) that can meet the needs of future wireless communication systems for railways by making positive train control (PTC) communication more interoperable, robust, reliable, spectrally efficient, and less costly to deploy and maintain. Cognitive radios (CRs) are a cutting-edge research area that combines artificial intelligence (AI) with software-defined radios (SDRs) with the goal of improving upon existing radio performance. SDRs are radios in which capabilities are flexible because of realizing some functionality in software as opposed to a purely hardware platform. By using situational awareness from the radio in the form of observable parameters, often known as meters, a cognitive engine (CE) uses software-based decision-making and learning algorithms to determine whether a change in the radio parameters, commonly referred to as knobs, is required based on sets of predefined goals.

Dynamic reconfiguration of software defined radios using standard architectures

Jeffrey H. Reed, A.R. Cormier, Carl B. Dietrich, Jeremy Price,
Journal PaperPhysical Communication, vol. 3, no. 2, June 2010, Pages 73-80 ,doi:10.1016/j.phycom.2009.09.002


The software defined radio (SDR) has opened the doors for levels of radio reconfiguration not possible through the use of more traditional radio design approaches. While most radios allow variation of parameters such as carrier frequency, an SDR enables large-scale reconfiguration (e.g., changing to a different protocol type or MAC). In this research, we explore automated, dynamic large-scale radio reconfiguration through the implementation and characterization of three alternative reconfigurable radio designs. These implementations seek to quantify the impacts of implementing large-scale radio reconfiguration through SDR application management enabled by the Software Communications Architecture (SCA) and similar SDR architectures. The SCA, a widely used SDR standard developed by the US Department of Defense, primarily supports static configurations with infrequent reconfiguration. However, we present a novel approach that uses features of the SCA and its enabling technologies to achieve rapid dynamic reconfiguration of SDRs. The act of radio reconfiguration through SCA application management is found to momentarily decrease the radio throughput. Although some overhead is experienced in the demonstration systems, the methods discussed achieve a high degree of flexibility through the use of standard SDR architectures.

A Survey of Artificial Intelligence for Cognitive Radios

Jeffrey H. Reed, An He, Kyung Kyoon Bae, T.R. Newman, J. Gaeddert, K. Kim, R. Menon, L. Morales, J. Neel, Y Zhao, W.H. Tranter
Journal PaperVehicular Technology, IEEE Transactions on , vol.59, no.4, pp.1578,1592, May 2010 doi: 10.1109/TVT.2010.2043968


Cognitive radio (CR) is an enabling technology for numerous new capabilities such as dynamic spectrum access, spectrum markets, and self-organizing networks. To realize this diverse set of applications, CR researchers leverage a variety of artificial intelligence (AI) techniques. To help researchers better understand the practical implications of AI to their CR designs, this paper reviews several CR implementations that used the following AI techniques: artificial neural networks (ANNs), metaheuristic algorithms, hidden Markov models (HMMs), rule-based systems, ontology-based systems (OBSs), and case-based systems (CBSs). Factors that influence the choice of AI techniques, such as responsiveness, complexity, security, robustness, and stability, are discussed. To provide readers with a more concrete understanding, these factors are illustrated in an extended discussion of two CR designs.

Fine Grained Scalability Video Multicast in Cognitive Radio Networks

Jeffrey H. Reed, Donglin Hu, Shiwen Mao, Y. Thomas Hou
Journal PaperIEEE Journal on Selected Areas in Communications, Special Issue on Wireless Video Transmission, vol.28, no.3, pp.334--344, April 2010


We investigate the problem of scalable video multicast in emerging cognitive radio (CR) networks. Although considerable advances have been made in CR research, such important problems have not been well studied. Naturally, 'bandwidth hungry' multimedia applications are excellent candidates for fully capitalizing the potential of CRs. We propose a crosslayer optimization approach to multicast video in CR networks. Specifically, we consider an infrastructure-based CR network collocated with N primary networks and model CR video multicast over the N channels as a mixed integer nonlinear programming (MINLP) problem. The objective is three-fold: to optimize the overall received video quality; to achieve proportional fairness among multicast users; and to keep the interference to primary users below a prescribed threshold. We propose a sequential fixing algorithm and a greedy algorithm to solve the MINLP, while the latter has low complexity and proven optimality gap. Our simulations with MPEG-4 fine grained scalability (FGS) video demonstrate the efficacy and superior performance of the proposed algorithms.

Experiences From the OSSIE Open Source Software Defined Radio Project

Jeffrey H. Reed, Carl B. Dietrich, Stephen H. Edwards, Frank E. Kragh
Journal PaperOpen Source Business Resource, March, 2010.


This article briefly describes OSSIE, a university-based open source Software Defined Radio (SDR) project based on the U.S. Department of Defense's Software Communications Architecture (SCA). The OSSIE software has proven useful for rapid prototyping by industry as well as for published research and education of hundreds of graduate and undergraduate students and short course participants. In addition to examples of OSSIE's successes, the project's challenges and approaches to mitigating and overcoming them are described

Interference Avoidance in Networks with Distributed Receivers

Jeffrey H. Reed, Menon, R. Macke, A Buehrer M.
Journal PaperIEEE Transactions on Wireless Communications, Vo.57, Issue 10, October 2009, pp. 3078-3091


Direct extensions of distributed greedy interference avoidance (IA) techniques developed for centralized networks to networks with multiple distributed receivers (as in ad hoc networks) are not guaranteed to converge. Motivated by this fact, we develop a waveform adaptation (WA) algorithm framework for IA based on potential game theory. The potential game model ensures the convergence of the designed algorithms in distributed networks and leads to desirable network solutions. Properties of the game model are then exploited to design distributed implementations of the algorithm that involve limited feedback in the network. Finally, variations of IA algorithms including IA with respect to legacy systems and IA with combined transmit-power and WA adaptations are investigated.

Analysis and Implementation of a Time-Interleaved ADC Array for a Software-Defined UWB Receiver

Jeffrey H. Reed, Anderson, C.R.; Venkatesh, S.; Ibrahim, J.E.; Buehrer, R Michael
Journal PaperVehicular Technology, IEEE Transactions on , vol.58, no.8, pp.4046,4063, Oct. 2009


A software-defined radio (SDR) for ultrawideband (UWB) communication systems places several stringent requirements on the analog-to-digital converter (ADC). One alternative to using a single ADC is to sample the received signal with an array of lower speed ADCs that were driven by interleaved sampling clocks; however, mismatches among the ADCs will result in signal distortion. This paper makes three important contributions to overcoming this problem: 1) analytical quantification of the impact of ADC gain, offset, and timing mismatches on the performance of a time-interleaved sampling ADC array for UWB signals; 2) demonstration of the efficacy of using a pilot-based matched-filter architecture to mitigate the impact of timing mismatches in the presence of multipath; and 3) implementation of an 8-ADC time-interleaved UWB SDR testbed that operates at an effective sampling frequency of 6.4 GHz. In addition, our findings allow for the design specification of the number of pilots required to obtain a desired system performance. The simulation and measured performance results from this paper demonstrate that ADC mismatches can be controlled to within plusmn10%, yielding acceptable levels of distortion and bit-error-rate (BER) performance on the UWB SDR testbed. Both analytical and simulation results also demonstrate the efficacy of a pilot-based matched filter in mitigating the impact of timing mismatch errors, even in the presence of multipath.

Open-source SCA-based core framework and rapid development tools enable software-defined radio education and research

Jeffrey H. Reed, Gonzalez, C.R.A; Dietrich, C.B.; Sayed, S.; Volos, H.I; Gaeddert, J.D.; Robert, P.M.; Kragh, F.E
Journal PaperCommunications Magazine, IEEE , vol.47, no.10, pp.48,55, October 2009


This article describes the Open Source SCA Implementation::Embedded project, an open source software development kit designed for rapid prototyping of software defined radios consistent with the software communications architecture. The SCA is a product of the American military's SDR acquisition program and has played a large role in SDR development in the military and in the wireless industry. OSSIE was designed for use in wireless communications curricula and research efforts, so it is easy to learn and illustrative of software engineering, programming, and communications engineering concepts important in industrial practice today. OSSIE includes a core framework (i.e., common services enumerated in the SCA). It also includes graphical user interface-oriented tools that are easily learned and free to download and use. The tools auto-generate SCA-specific component source code and supporting files, leaving the developer to provide signal processing functionality. In addition, visualization tools for debugging and a growing library of SDR software components are available. Discussed herein are examples of SDRs designed using OSSIE, including embedded applications. OSSIE enables easy transition from concepts to practice in SDR design for communications engineers who may not have a strong software background.

Understanding the Software Communications


Jeffrey H. Reed, Gonzalez, C.R.A; Dietrich, C.B.;
Journal PaperIEEE , vol.47, no.9, pp.50,57, September 2009


The Software Communications Architecture is an open architecture developed by the U.S. Department of Defense to standardize the development of software-defined radio, improve communication systems interoperability, and reduce development and deployment costs. The SCA facilitates software reuse and technology insertion by abstracting radio applications from the supporting platform and defining a common operational environment across platforms. The SCA relies on commercial standards, classic software engineering principles, and software design patterns. While some SCA design choices are controversial and tightly tied to the specific needs for which it was developed, the basic design principles of software reuse and abstraction are sound and necessary if SDR is to achieve its full potential. Some of the techniques and concepts used in the SCA may be foreign to a communications engineer, and can result in confusion and long learning curves. The understanding of these concepts is of great relevance for communications engineers independent of any opinion about the SCA itself. This tutorial is aimed at educating communication engineers on these software engineering principles and describing how the SCA applies them to achieve its goals. We describe the different interfaces of the SCA that provide a framework for the implementation of SDR. The tutorial provides introductory material to understand the basic operation of the SCA as implemented in the Open-Source SCA Implementation::Embedded developed by Wireless @ Virginia Tech.

Utility Function Selection for Streaming Videos with a Cognitive Engine Test Bed


Jeffrey H. Reed, Y. Zhao, S. Mao, Y Huang
Journal PaperACM/Springer Mobile Networks and Applications (MONET) at SpringerLink, August 18, 2009


Abstract Cognitive Radio (CR) is a new wireless communication and networking paradigm that is enabled by the Software Defined Radio (SDR) technology and the recent change in spectrum regulation policy. As the first commercial application of CR technology, IEEE 802.22 wireless regional area networks (WRAN) aim to offer broadband wireless access by efficiently utilizing the unoccupied TV channels. In this paper, we investigate the problem of utility function selection and its impact on streaming video quality through an IEEE 802.22 WRAN base station (BS) cognitive engine (CE) testbeddeveloped at Wireless@Virginia Tech. We find that significant improvement on received video quality can be achieved when CE adopts a dynamic, content-aware, video-specific utility function rather than a static, predefined, general purpose utility function. This work indicates the importance of video distortion modeling and cross-layer design, and the need for edynamic content-aware utility functions at the CE for employing cognitive streaming video communication networks.

Accurate Bit Error Rate Analysis of Bandlimited Cooperative OSTBC Networks UnderTime Synchronization Errors

Jeffrey H. Reed, An He, Joseph Gaeddert, Kyung Kyoon Bae, Timothy R. Newman, R. Chembil Palat, A. Annamalai
Journal Paper Vehicular Technology, IEEE Transactions on , vol.58, no.5, pp.2191,2200, Jun 2009


The distributed multiple-input-multiple-output (MIMO) system (e.g., intercluster communication via cooperating nodes in a wireless sensor network) is a topic of emerging interest. Many previous studies have assumed perfect synchronization among cooperating nodes and identically distributed communication links. Such assumptions are rarely valid in practical operating scenarios. This paper develops an analytical framework for computing the average bit error rate (ABER) of a distributed multiple-input-single-output (MISO) space-time-coded system with binary phase shift keying (BPSK) modulation affected by timing synchronization errors. The cooperating nodes use data pulse-shaping filters for transmission over generalized frequency-nonselective fading channels. As an illustrative example, the performance evaluation of a 2 times 1 MISO system that uses distributed orthogonal space-time block coding (OSTBC) is presented, although this approach can be readily extended to analyze distributed transmit diversity with a larger number of cooperating nodes. We show that under certain conditions, a distributed MISO system with time synchronization errors can still outperform a perfectly synchronized single-input-single-output (SISO) system

Spectrum Sensing for Cognitive Radio

Jeffrey H. Reed, S. Haykin, D.J. Thomson
Journal PaperHaykin, Simon; Thomson, D.J.; Reed, J.H., "Spectrum Sensing for Cognitive Radio," Proceedings of the IEEE , vol.97, no.5, pp.849,877, May 2009


Spectrum sensing is the very task upon which the entire operation of cognitive radio rests. For cognitive radio to fulfill the potential it offers to solve the spectrum underutilization problem and do so in a reliable and computationally feasible manner, we require a spectrum sensor that detects spectrum holes (i.e., underutilized subbands of the radio spectrum), provides high spectral-resolution capability, estimates the average power in each subband of the spectrum, and identifies the unknown directions of interfering signals. Cyclostationarity is another desirable property that could be used for signal detection and classification. The multitaper method (MTM) for nonparametric spectral estimation accomplishes these tasks accurately, effectively, robustly, and in a computationally feasible manner. The objectives of this paper are to present: 1) tutorial exposition of the MTM, which is expandable to perform space-time processing and time-frequency analysis; 2) cyclostationarity, viewed from the Loeve and Fourier perspectives; and 3) experimental results, using Advanced Television Systems Committee digital television and generic land mobile radio signals, followed by a discussion of the effects of Rayleigh fading.

A Game-Theoretic Framework for Interference Avoidance

Jeffrey H. Reed, Menon, R.; MacKenzie, AB.; Hicks, J.; Buehrer, R.M.
Journal Paper Communications, IEEE Transactions on , vol.57, no.4, pp.1087,1098, April 2009


Various iterative algorithms for interference avoidance (IA) in networks with co-located receivers, suitable for distributed implementation, have been proposed in the literature. In this paper, the IA problem is cast in a game-theoretic framework and is formulated as a potential game. This formulation accommodates previously proposed algorithms and, in addition, gives us a framework that enables the design of new distributed and convergent algorithms for IA including algorithms with nonidentical utility functions for the users. Two new convergence results for potential games are then derived. The first result establishes the convergence of a class of potential games to the global solution while following best response iterations and when noise is added. The second result establishes the convergence of potential games to the Nash equilibria of the game while following random better response iterations. The first result combined with the potential game formulation allows us to show that for a large class of network scenarios, arbitrarily small noise assures the convergence of best response IA algorithms, including the eigeniterations, to an arbitrarily small neighborhood of the globally optimal signature sequence set. The second result enables the design of reduced feedback mechanisms for IA that converge to desirable solutions.

Development of a Case-Based Reasoning Cognitive Engine for IEEE 802.22 WRAN Applications

Jeffrey H. Reed, An He, J. Gaeddert, K. Bae, T. Newman, I. Morales, and C. H. Park
Journal PaperACM SIGMOBILE Mobile Computing and Communications Review, Volume 13 Issue 2, April 2009, New York pp. 37-48; ISSN: 1559-1662 EISSN: 1931-1222


On Nov. 4 2008, the Federal Communications Commission adopted rules for unlicensed use of television white spaces. The IEEE 802.22 Wireless Regional Area Networks (WRAN) standard is the first IEEE standard utilizing cognitive radio (CR) technology to exploit the television white space. A decision engine that is able to respond to the changes in the radio environment is necessary to efficiently exploit underutilized spectrum resources and avoid interfering with the licensed systems (e.g., TV services). This paper discusses the development of a case-based reasoning cognitive engine (CBR-CE) for the IEEE 802.22 WRAN applications. The performance of the CBR-CE is evaluated under various radio scenarios and compared to that of several multi objective search based algorithms, including the hill climbing search (HCS) and the genetic algorithm (GA). The simulation results show that the developed CBR-CE can achieve comparable utility with faster adaptation than the search based cognitive engines after appropriate training / learning. The learning process of the CBR is also simulated and discussed.

Cognitive Radio and Networking Research at Virginia Tech

Jeffrey H. Reed, A. B. Mackenzie, P. Athanas, C. W. Bostian, R. M. Buehrer, L. A. DaSilve, S. W. Ellingson, Y. T. Hou, M. Hsiao, J. M. Park, C. Patterson, S. Raman, and C. R. C. M. da Silva
Journal Paper Proceedings of the IEEE, vol. 97,no. 4, pp. 660-688, April 2009


More than a dozen Wireless @ Virginia Tech faculty are working to address the broad research agenda of cognitive radio and cognitive networks. Our core research team spans the protocol stack from radio and reconfigurable hardware to communications theory to the networking layer. Our work includes new analysis methods and the development of new software architectures and applications, in addition to work on the core concepts and architectures underlying cognitive radios and cognitive networks. This paper describes these contributions and points towards critical future work that remains to fulfill the promise of cognitive radio. We briefly describe the history of work on cognitive radios and networks at Virginia Tech and then discuss our contributions to the core cognitive processing underlying these systems, focusing on our cognitive engine. We also describe developments that support the cognitive engine and advances in radio technology that provide the flexibility desired in a cognitive radio node. We consider securing and verifying cognitive systems and examine the challenges of expanding the cognitive paradigm up the protocol stack to optimize end-to-end network performance. Lastly, we consider the analysis of cognitive systems using game theory and the application of cognitive techniques to problems in dynamic spectrum sharing and control of multiple-input multiple-output radios.

Performance Evaluation of Cognitive Radios: Metrics, Utility Functions, and Methodology

Jeffrey H. Reed, Youping Zhao; Shiwen Mao; Neel, James O.
Journal Paper Proceedings of the IEEE , vol.97, no.4, pp.642,659, April 2009


Performance evaluation of cognitive radio (CR) networks is an important problem but has received relatively limited attention from the CR community. Unlike traditional radios, a cognitive radio may change its objectives as radio scenarios vary. Because of the dynamic pairing of objectives and contexts, it is imperative for cognitive radio network designers to have a firm understanding of the interrelationships among goals, performance metrics, utility functions, link/network performance, and operating environments. In this paper, we first overview various performance metrics at the node, network, and application levels. From a game-theoretic viewpoint, we then show that the performance evaluation of cognitive radio networks exhibits the interdependent nature of actions, goals, decisions, observations, and context. We discuss the interrelationships among metrics, utility functions, cognitive engine algorithms, and achieved performance, as well as various testing scenarios. We propose the radio environment map-based scenario-driven testing (REM-SDT) for thorough performance evaluation of cognitive radios. An IEEE 802.22 WRAN cognitive engine testbed is presented to provide further insights into this important problem area.

Exploiting Location Information for Concurrent Transmissions in Multihop Wireless Networks

Jeffrey H. Reed, Seung Min Hur; Shiwen Mao; Hou, Y.T.; Kwanghee Nam
Journal PaperVehicular Technology, IEEE Transactions on , vol.58, no.1, pp.314,323, Jan. 2009


In a multihop wireless network environment, it has been shown that IEEE 802.11 media access control (MAC) suffers from a low-throughput problem, which is largely due to the inefficiency in carrier sensing and spatial reuse. In this paper, we present a location-assisted MAC protocol that schedules ldquofeasiblerdquo concurrent transmissions in a multihop wireless network. A simple procedure based on location information is adopted in the proposed MAC to validate the feasibility of a concurrent transmission. Our simulation results show that the proposed scheme can effectively increase the throughput and reduce the average end-to-end delay of multihop wireless networks.

Technical Standard for Unlicensed Radio Device on DTB Band in U.S.A.

Jeffrey H. Reed, D.-K. Park, T. Saba
Journal PaperIEICE Trans. Commun., (Japanese Edition), vol. J91-B, no. 11, pp. 1351-1358, November 2008.


To meet the large and rapidly increasing demand of radio resources in the world, a new spectrum utilization policy that can maximize the efficiency of frequency utilization and can accommodate more wireless services is under consideration. Recently, the increase of the efficient use of radio resources based on cognitive radio technology is studied. In the United States, the frequency re-allocation in the VHF/UHF band is carried out along with the switchover from analogue to digital TV. It is expected that the application of cognitive radio technology for this band would provide more efficient and effective use and would have significant benefits for the public by allowing the development of new and innovative types of unlicensed radio devices. This paper describes the trends of the radio regulatory policy and the technical standard for the operation of unlicensed devices on the TV band in the U.S.

Toward Secure Distributed Spectrum Sensing in Cognitive Radio Networks

Jeffrey H. Reed, Ruiliang Chen; Jung-Min Park; Hou, Y.T
Journal PaperCommunications Magazine, IEEE , vol.46, no.4, pp.50,55, April 2008


Cognitive radio is a revolutionary technology that promises to alleviate the spectrum shortage problem and to bring about remarkable improvement in spectrum utilization. Spectrum sensing is one of the essential mechanisms of CR and is an active area of research. Although the operational aspects of spectrum sensing are being studied actively, its security aspects have attracted very little attention. In this paper, we discuss security issues that may pose a serious threat to spectrum sensing. Specifically, we focus on two security threats - incumbent emulation and spectrum sensing data falsification - that may wreak havoc in distributed spectrum sensing. We also discuss methods for countering these threats and the technical hurdles that must be overcome to implement such countermeasures.

On the Impact of Dynamic Spectrum Sharing Techniques on LegacyRadio Systems

Jeffrey H. Reed, Rekha Menon, R Michael Buehrer
Journal PaperWireless Communications, IEEE Transactions on , vol.7, no.11, pp.4198,4207, November 2008


The biggest challenge faced by dynamic spectrum sharing (SS) systems is the design of SS schemes that do not adversely impact existing legacy systems in the absence of perfect knowledge. We address this issue by developing a framework to evaluate the interference profile at a legacy receiver under different system scenarios which include the hidden node and imperfect-sensing problems. By analyzing the interference distributions and by comparing the two basic approaches to SS - interference-avoidance-based overlay and interference averaging-based underlay - we identify desirable characteristics for SS radio systems.We then leverage this knowledge to motivate the use of a hybrid SS approach that combines the benefits of the two basic approaches and substantially reduces the impact to the legacy system. The advantage provided by this approach is shown to increase with an increase in the bandwidth available to the SS system. In addition, the approach is more robust to imperfect information. The inclusion of log-normal shadowing is shown to further accentuate these performance trends.

An Efficient Method for Evaluating Information Outage Probability and Ergodic Capacity of OSTBC System

Jeffrey H. Reed, Palat, R.C.; Annamalai, A
Journal Paper Communications Letters, IEEE , vol.12, no.3, pp.191,193, March 2008


Several numerical methods have been suggested in the past to compute the outage probability and the ergodic capacity of an orthogonal space-time block coding system. In this paper we add to this body of work by describing a simpler yet general method that relies on a more efficient Fixed-Talbot algorithm for numerical Laplace inversion. The framework developed can be applied to a wide range of fading distributions (including Rice, Nakagami-m, Nakagami-Hoyt and Weibull stochastic channel models) with unequal channel gains and also to independent and non-identically distributed (i.n.d) multiple input multiple output channels.

Defense Against Primary User Emulation Attacks in Cognitive Radio Networks

Jeffrey H. Reed, Ruiliang Chen; Jung-Min Park;
Journal Paper Selected Areas in Communications, IEEE Journal on , vol.26, no.1, pp.25,37, Jan. 2008


Cognitive radio (CR) is a promising technology that can alleviate the spectrum shortage problem by enabling unlicensed users equipped with CRs to coexist with incumbent users in licensed spectrum bands while causing no interference to incumbent communications. Spectrum sensing is one of the essential mechanisms of CRs and its operational aspects are being investigated actively. However, the security aspects of spectrum sensing have garnered little attention. In this paper, we identify a threat to spectrum sensing, which we call the primary user emulation (PUE) attack. In this attack, an adversary's CR transmits signals whose characteristics emulate those of incumbent signals. The highly flexible, software-based air interface of CRs makes such an attack possible. Our investigation shows that a PUE attack can severely interfere with the spectrum sensing process and significantly reduce the channel resources available to legitimate unlicensed users. To counter this threat, we propose a transmitter verification scheme, called LocDef (localization-based defense), which verifies whether a given signal is that of an incumbent transmitter by estimating its location and observing its signal characteristics. To estimate the location of the signal transmitter, LocDef employs a non-interactive localization scheme. Our security analysis and simulation results suggest that LocDef is effective in identifying PUE attacks under certain conditions.

On Joint Routing and Server Selection for MD Video Streaming in Ad Hoc Networks

Jeffrey H. Reed, Shiwen Mao; Xiaolin Cheng; Hou, Y.T.; Sherali, H.D.
Journal Paper Wireless Communications, IEEE Transactions on , vol.6, no.1, pp.338,347, Jan. 2007


For media streaming in ad hoc networks, service replication has been demonstrated to be a quite effective countermeasure to streaming interruptions caused by fragile paths and dynamic topology. In this paper, we study the problem of joint routing and server selection for double description (DD) video streaming in ad hoc networks. We formulate the task as a combinatorial optimization problem and present tight lower and upper bounds for the achievable distortion. The upper bound provides a feasible solution to the formulated problem. Our extensive numerical results show that the bounds are very close to each other for all the cases studied, indicating the near-global optimality of the derived upper bounding solution. Moreover, we observe significant gains in video quality achieved by the proposed approach over existing server selection schemes. This justifies the importance of jointly considering routing and server selection for optimal MD video streaming

Design and Implementation of an SCA Core Framework for a DSP Platform, Part 1 & 2

Jeffrey H. Reed, Shiwen Mao; Xiaolin Cheng; Hou, Y.T.; Sherali, H.D.
Journal Paper Wireless Communications, IEEE Transactions on , vol.6, no.1, pp.338,347, Jan. 2007


The Software Commuications Architecture (SCA) was de-veloped to improve software reuse and interoperability in Software Defined Radios (SDR). However, there have been performance concerns since its conception. Arguably, the majority of the problems and inneficiencies associated with the SCA can be attributed to the assumption of modular distributed platforms relying on General Purpose Processors (GPPs) to perform all signal processing. Significant improve-ments in cost and power consumption can be obtained by utilizing specialized, more efficient platforms. Digital Signal Processors (DSPs) present such a platform and have been widely used in the communications industry. Improvements in development tools and middleware technology opened the possibility of fully integrating DSPs into the SCA.


Part one | Part two

Interference Reducing Networks

Jeffrey H. Reed, Neel, James O.; Menon, Rekha; MacKenzie, AB.; Gilles, Robert P.,
Journal Paper Cognitive Radio Oriented Wireless Networks and Communications, 2007.
CrownCom 2007. 2nd International Conference on, vol., no., pp.96,104, 1-3 Aug. 2007


When cognitive radios operate in a network, each link's adaptations impact the decisions of other cognitive radios which spawns an interactive decision processes. The existence of these interactive processes could potentially limit the deployment of cognitive radios as it is difficult to guarantee that the resulting behavior will avoid a tragedy of the commons, much less provide optimal performance. This paper proposes a novel design framework that ensures that cognitive radio interactions are beneficial and reduce sum network interference with each adaptation. Five different approaches to implementing algorithms that satisfy this framework are presented , two of which rely on collaboration and three which permit autonomous adaptations.

Smart Antenna Base Station Open Architecture for SDR Networks

Jeffrey H. Reed, Namkyu Ryu; Yusuk Yun; Seungwon Choi; Palat, R.C.;
Journal Paper Wireless Communications, IEEE , vol.13, no.3, pp.58,69, June 2006


Software-defined radio system architecture must be openly structured to various system standards. It should also provide capability for distributed processing, object-oriented design, and software controllability. This implies that the software to be used in the SDR system should be independent of a given hardware platform. In> order to achieve these goals, the proposed SDR system utilizes modularization to maximize hardware reuse and design flexibility, which provides the system reconfigurability. The objective of this article is to provide an open architecture of a smart antenna base station (SABS) operating in the SDR with architecture that is object-oriented and software-controlled. For this purpose, the software and hardware of a SABS is first modularized and partitioned into modules, respectively. Then the interface among the modules is specified to determine the smart antenna application programming interface proper for the SDR network. The suitability of the proposed open architecture of SABS is verified through a design example of SABS implemented in accordance with the proposed architecture. The performance of the proposed system is shown in practical signal environments of CDMA2000 1X with commercial handsets operating at various data rates ranging from 9.6 to 153.6 kb/s in terms of frame error rate and signal- to-Interference-plus-noise ratio, which is dramatically improved through the nicely shaped beam pattern.

The Resurgence of Push-to-Talk Technologies

Jeffrey H. Reed, DaSilva, L.A; Morgan, G.E.; Bostian, C.W.; Sweeney, D.G.; Midkiff, S.F.; Thompson, C.; Newhall, W.G.; Woerner, B.,
Journal Paper Communications Magazine, IEEE , vol.44, no.1, pp.48,55, Jan. 2006


Push-to-talk (PTT) technologies date back to the advent of the telegraph and more recently have been the domain of traditional land mobile radio (LMR) networks. The past few years have brought about a resurgence in PTT as a service offered by commercial providers, driven first by private subscribers and, increasingly, by organizations such as law enforcement agencies that traditionally rely on LMRs. This technology, today one of the growth areas in the communications industry, has received little attention in the scientific literature. In this article, we discuss some of the emerging technologies (voice over IP, CDMA used in 2.5G/3G systems) that relate to today's PTT service. We also discuss the market and financial implications of commercial PTT on current LMR deployments.

Using Game Theory to Analyze Wireless Ad Hoc Networks

Jeffrey H. Reed, Srivastava, V.; Neel, J.; MacKenzie, AB.; Menon, R.; Dasilva, L.A; Hicks, Gilles, R.P
Journal Paper Communications Surveys & Tutorials, IEEE, vol.7, no.4, pp.46,56, Fourth Quarter 2005


The application of mathematical analysis to the study of wireless ad hoc networks has met with limited success due to the complexity of mobility and traffic models, the dynamic topology, and the unpredictability of link quality that characterize such networks. The ability to model individual, independent decision makers whose actions potentially affect all other decision makers renders game theory particularly attractive to analyze the performance of ad hoc networks. In this article we describe how various interactions in wireless ad hoc networks can be modeled as a game. This allows the analysis of existing protocols and resource management schemes, as well as the design of equilibrium-inducing mechanisms that provide incentives for individual users to behave in socially-constructive ways. We survey the recent literature on game theoretic analysis of ad hoc networks, highlighting its applicability to power control and waveform adaptation, medium access control, routing, and node participation, among others.

Analog-to-Digital Converters

Jeffrey H. Reed, Bin Le; Rondeau, T.W.; Bostian, C.W.,
Journal Paper Signal Processing Magazine, IEEE , vol.22, no.6, pp.69,77, Nov. 2005


This paper analyzed the internal relationships of the performance parameters of ADCs, showing their frequency dependency and structure dependency. The history and current trends in ADC technologies based on the P and F figures-of-merit were also reviewed. Historically, there was an increase in performance around 1994, with a share rise around 1997, which broke the stagnant performance discussed by Waiden (1999). While the past few years have shown a sharp increase in ADC performance, we have shown that performance and power dissipation depend greatly on the ADC structure and the target applications. With the progression of wideband radio systems like UWB and OFDM comes a growing demand to provide faster sampling rates and higher resolutions with lower power dissipation. With the innovation of advanced communication techniques like multi-input/multi-output and multistandard radios, the demand is growing to provide multichannel programmable data conversion, both of which are pushing the performance of ADCs further in the coming years

Design And Implementation Of A DSP-Based MIMO System Prototype For Real-Time Demonstration And Indoor Channel Measurements

Jeffrey H. Reed, R. Mostafa, R. Gozali, P. M. Robert, R. Chembil Palat, B. D. Woerner
Journal Paper Eurasip J. Applied Signal Processing, vol. 2005, no. 16, pp. 2673-2685, September 2005


The design and implementation of the Virginia Tech Space-Time Advanced Radio (VT-STAR), a multiple antenna element space-time (ST) processing prototyp presented. The testbed is a research tool for comparing practical and theoretical performance metrics (eg, throughput, link reliability) in different wireless channel conditions. The prototype builds around software-defined radio (SDR) concepts on a DSP platformand provides the flexibility to implement various forms of ST techniques.

Performance Evaluation Of Cellular Mobile Radio Systems With Adaptive Interference Nulling of dominant interferers

Jeffrey H. Reed, Mostafa, R.; Annamalai, A
Journal Paper Communications, IEEE , vol.52, no.2, pp.326,335, Feb. 2004


This paper develops an analytical framework for characterizing the average symbol error rate and outage performance of a smart antenna system in cellular mobile radio environments. Specifically, the carrier-to-interference ratio statistics with N remaining (uncancelled) "weakest" cochannel interference (CCI) signals from a total of NI signals are derived, given that both the desired user signal and the CCI signal amplitudes are subjected to Rayleigh, Rice, Nakagami-m, or Nakagami-q fading. General expressions for the outage probability and the average symbol-error rate performance of different digital modulation schemes in the presence of CCI signals are derived. Selected numerical results are presented to demonstrate the utility of the analysis in assessing the selective interference ing performance in different fading environments.

An Overview Of Configurable Computing Machines For Software Radio Handsets

Jeffrey H. Reed, Srikanteswara, S.; Palat, R.C.; Athanas, P.,
Journal Paper Communications Magazine, IEEE, vol.41, no.7, pp.134,141, July 2003


The advent of software radios has brought a paradigm shift to radio design. A multimode handset with dynamic reconfigurability has the promise of integrated services and global roaming capabilities. However, most of the work to date has been focused on software radio base stations, which do not have as tight constraints on area and power as handsets. Base station software radio technology progressed dramatically with advances in system design, adaptive modulation and coding techniques, reconfigurable hardware, A/D converters, RF design, and rapid prototyping systems, and has helped bring software radio handsets a step closer to reality. However, supporting multimode radios on a small handset still remains a design challenge. A configurable computing machine, which is an optimized FPGA with application-specific capabilities, show promise for software radio handsets in optimizing hardware implementations for heterogeneous systems. In this article contemporary CCM architectures that allow dynamic hardware reconfiguration with maximum flexibility are reviewed and assessed. This is followed by design recommendations for CCM architectures for use in software radio handsets.

Bit Error Rate Estimation Using Probability Density Function Estimators

Jeffrey H. Reed, Laster, J.D.; Tranter, W.H.,
Journal Paper Vehicular Technology, IEEE Transactions on, vol.52, no.1, pp.260,267, Jan 2003


The concept of real-time bit error rate (BER) estimation based on probability density function (PDF) estimators of the decision statistic is discussed. Communications systems need techniques to approximate real-time BER estimation without resorting to brute-force error counting methods. Due to the dynamic nature of the wireless channel, a priori (deductive) estimation techniques (e.g., where knowledge of signal impairments is assumed before demodulation) are often unreliable. A posteriori (inductive) estimation techniques (e.g., where knowledge of signal impairments is acquired after the signal is demodulated) are preferable because they assume no prior knowledge of the channel. Two a posteriori techniques are described that yield reliable BER estimates over small observation intervals: (1) the Gram-Charlier series approximation for PDFs and (2) Parzen's PDF estimator. Robust estimators of location and scale are also employed to improve the performance of Gram-Charlier estimation. The performance of BER estimation based on the PDF estimators is validated by simulations. A 1-bit differential demodulator (DD1) is used to demodulate a Gaussian minimum shift keying signal, and Gram-Charlier-based and Parzen (1962) based BER estimations are compared to measured DD1 results. Comparisons are made for BER estimation versus measured BER in additive white Gaussian noise (AWGN) and cochannel interference (CCI) channels and in urban multipath with AWGN and CCI.

Geometrical-Based Statistical Macrocell Channel Model For Mobile Environments

Jeffrey H. Reed, Petrus, P.; Rappaport, T.S.,
Journal Paper Communications, IEEE Transactions on, vol.50, no.3, pp.495,502, Mar 2002


We develop a statistical geometric propagation model for a macrocell mobile environment that provides the statistics of angle-of-arrival (AOA) of the multipath components, which are required to test adaptive array algorithms for cellular applications. This channel model assumes that each multipath component of the propagating signal undergoes only one bounce traveling from the transmitter to the receiver and that scattering objects are located uniformly within a circle around the mobile. This geometrically based single bounce macrocell (GBSBM) channel model provides three important parameters that characterize a channel: the power of the multipath components, the time-of-arrival (TOA) of the components, and the AOA of the components. Using the GBSBM model, we analyze the effect of directional antennas at the base station on the fading envelopes. The level crossing rate of the fading envelope is reduced and the envelope correlation increases significantly if a directional antenna is employed at the base station

3G Around The World And Back Again

Jeffrey H. Reed, Raqibul Mostafa, Fakhrul Alam, Kyung Kyoon Bae, WH Tranter, BD Woerner
Journal Paper RF Design, February 2002


A radio frequency transceiver reference design for third generation UTRA/FDD W-CDMA cellular handset is presented in this paper, A number of commercial RFICs are analyzed by considering the heterodyne architecture implementation of the transceiver. Requirements and considerations in the cellular handset radio frequency transceiver design are also discussed. Numerical analysis and measurement results obtained in this work could be used as a reference design for immediate RF transceiver hardware implementation in commercial 3G W-CDMA cellular handsets.

Overloaded Array Processing With Spatially Reduced Search Joint Detection

Jeffrey H. Reed, Hicks, J.; Bayram, S.; Tranter, W.H.; Boyle, R.J.;
Journal Paper Selected Areas in Communications, IEEE Journal on , vol.19, no.8, pp.1584,1593, Aug 2001


An antenna array is overloaded when the number of cochannel signals in its operating environment exceeds the number of elements. This paper proposes an iterative joint detection technique, spatially reduced search joint detection (SRSJD), that well approximates the joint maximum likelihood (JML) receiver, while reducing its computational complexity by several orders of magnitude. This complexity reduction is achieved by first exploiting the spatial separation between interfering signals with a linear preprocessing stage, and second, performing iterative joint detection with a reduced-state trellis formed over space instead of time. These novel joint detection trellises are possibly tail-biting and vary in structure from stage to stage. Through simulation, SRSJD is shown to demodulate over 2M synchronous quaternary phase-shift keying signals of zero excess bandwidth with an M element circular array. The channels of all users are assumed known.

A Novel Direct Sequence Spread Spectrum CDMA System With Analog Frequency Modulation

Jeffrey H. Reed, T. Li, Y. M. Vasavada, B. D. Woerner
Journal Paper International J. Wireless Inform. Networks, vol. 7, no.1, pp. 43-53, 2000.


This paper describes and analyzes a unique combination of analog modulation with code division multiple access. Although the capacity of the analog CDMA system is less than that of the digital CDMA, the analog system has reliable voice quality, economy and ease of implementation, simplified frequency planning, and compatibility with current analog phone systems and devices, which is an especially attractive feature. The FM CDMA system is proposed as a fixed wireless system, e.g., wireless local loop, in which the small scale fading distortion due to Doppler effect is likely to be moderate. This allows the use of simple and cost-efficient receiver structures while maintaining performance.

Adaptive Single-User Receivers For Direct-Sequence Spread-Spectrum CDMA Ssystems

Jeffrey H. Reed, T. Majmundar, M.; Sandhu, N.
Journal Paper Vehicular Technology, IEEE Transactions on , vol.49, no.2, pp.379,389, Mar 2000


The capacity of a direct-sequence spread-spectrum code-division multiple-access (DSSS-CDMA) system is limited by multiple-access interference (MAI) and the near-far problem. Multiuser receivers provide a solution to these problems, but they require knowledge of parameters of the MAI and are computationally complex. Adaptive single-user receivers, however, do not require knowledge of MAI parameters and need fewer computations. This paper discusses a wide range of adaptive single-user receivers found in the literature and presents their performance results under a unified framework to provide a basis of comparison. Results indicate that, compared to the conventional receiver, adaptive single-user receivers provide large gains in system capacity and are near-far resistant. It is shown that fractionally spaced adaptive receivers, which exploit spectral correlation due to the cyclostationary nature of the DSSS signal, perform better than adaptive receivers that cannot exploit this correlation. Multipath results presented for two-ray and urban channels indicate that fractionally spaced adaptive receivers act as RAKE receivers.

Convergence Analysis Of The Least Squares Constant Modulus Algorithm In Interference Cancellation Applications

Jeffrey H. Reed, T. Biedka, T.E.; Tranter, W.H.;
Journal Paper Communications, IEEE Transactions on , vol.48, no.3, pp.491,501, Mar 2000


The convergence behavior of the least squares constant modulus (CM) algorithm in an adaptive beamforming application is examined. It is assumed that the desired signal and the interference are uncorrelated. The improvement in output signal-to-interference ratio (SIR) with each iteration of the algorithm is predicted for several different signal environments. Deterministic results are presented for an environment containing two complete sinusoids. Probabilistic results are presented for a CM desired signal with a CM interferer and with a Gaussian interferer. The asymptotic improvement in output SIR as the output SIR becomes high is also derived. The results of Monte Carlo simulations using sinusoidal, frequency modulation, and quadrature phase-shift keying signals are included to support the derivations

A Soft Radio Architecture For Reconfigurable Platforms

Jeffrey H. Reed, Srikanteswara, S.; Athanas, P.; Boyle, R
Journal PaperCommunications Magazine, IEEE , vol.38, no.2, pp.140,147, Feb 2000


While many soft/software radio architectures have been suggested and implemented, there remains a lack of a formal design methodology that can be used to design and implement these radios. This article presents a unified architecture for the design of soft radios on a reconfigurable platform called the layered radio architecture. The layered architecture makes it possible to incorporate all of the features of a software radio while minimizing complexity issues. The layered architecture also enables a methodology for incorporating changes and updates into the system. An example implementation of the layered architecture on actual hardware is presented

Angle And Time Of Arrival Statistics For Circular And Elliptical Scattering Models

Jeffrey H. Reed, R. B. Ertel
Journal Paper Selected Areas in Communications, IEEE Journal on , vol.17, no.11, pp.1829,1840, Nov 1999


With the introduction of antenna array systems into wireless communication networks comes the need to better understand the spatial characteristics of the channel. Scattering models provide both angle of arrival (AOA) and time of arrival (TOA) statistics of the channel. A number of different scattering models have been proposed in the literature including elliptical and circular models. These models assume that scatterers lie within an elliptical and circular region in space, respectively. In this paper, the joint TOA/AOA, the marginal TOA, and the marginal AOA probability density functions (PDFs) are derived for the elliptical and circular scattering models. These PDFs provide insight into the properties of the spatial wireless channel.

Adaptive Handoff Algorithms For Cellular Overlay Systems Using Fuzzy Logic

Jeffrey H. Reed, R. B. Ertel
Journal Paper Vehicular Technology Conference, 1999 IEEE 49th , vol.2, no., pp.1413,1418 vol.2, Jul 1999


An overlay system is a hierarchical architecture that uses large macrocells to overlay clusters of small microcells. Resource management in the overlay system is much more complex than in pure macrocell and microcell systems. A fixed parameter handoff algorithm cannot perform well in a complex and dynamic overlay environment. This paper proposes an adaptive overlay handoff algorithm that allows a systematic tradeoff among the system design parameters and improves the overall system performance.

Generation Of Two Equal Power Correlated Rayleigh Fading Envelopes

Jeffrey H. Reed, R. B. Ertel
Journal Paper Communications Letters, IEEE , vol.2, no.10, pp.276,278, Oct. 1998


A procedure for generating two equal power Rayleigh-fading envelopes with any desired cross-correlation coefficient is given. Having this ability will aid researchers in simulating correlated fading envelopes, which can be used to study the impact of correlation on the performance of diversity systems

An Overview Of The Challenges And Progress In Meeting The E-911 Requirement For Location Service

Jeffrey H. Reed, Kevin J Krizman, Brian D Woerner, Theodore S Rappaport
Journal Paper IEEE Commun. Mag., pp. 30-37, April 1998


When the FCC created the rules for wireless Enhanced 911 (E-911) service, a flurry of research and development activities dedicated to locating the position of emergency callers followed. The current deadline for this capability is October 1, 2001. In this article, we review the unique challenges and some of the proposed approaches for each of the major wireless standards.

Capacity Enhancement Using Adaptive Arrays In An AMPS System

Jeffrey H. Reed, Petrus, P.; Ertel, R.B.
Journal Paper Vehicular Technology, IEEE Transactions on , vol.47, no.3, pp.717,727, Aug 1998


Adaptive arrays for an advanced mobile phone service (AMPS) system can significantly increase cell capacity, improve signal quality, and reduce transmitter power requirements. In this paper, we investigate the capacity improvement that can potentially be achieved using adaptive arrays at the base station of an AMPS system. For the analysis, we use two types of spatial filters at the base station: an ideal and flat-top beamformer. An ideal beamformer has a flat main lobe and no side lobes, while a flat-top beamformer has flat main and side lobes. Analysis includes calculation of outage probability when a beamformer is used at the base station, and then we calculate the capacity increase that can be offered by practical antenna arrays. In this paper, we show that spatial-division multiple access (SDMA), i.e., all the users in a cell occupying the same frequency, is impossible to achieve in an AMPS system. A cell-reuse factor of four can be easily achieved with a five-element uniform linear array (ULA) with λ/2 spacings, but to achieve a reuse factor of three, a ULA with eight elements is required

Geometrically Based Statistical Channel Model for Macrocellular Mobile Environments

Jeffrey H. Reed, Paul Petrust and Theodore S. Rappaport


In this paper, we develop a statistical geometric propagation model for a macrocell mobile environment that provides the statistics of angle-of-arrival of the multipath components. This channel model assumes that each multipath component of the propagating signal undergoes only one bounce traveling from the transmitter to the receiver and that scattering objects are located uniformly within a circle around the mobile. This Geometrically Based Single Bounce Macrocell (GBSBM) channel model provides three important parameters that characterize a channel: the power of the multipath components, the time-of-arrival (TOA) of the components, and the angle-of-arrival (AOA) of the components. Doppler spectra and fading envelopes obtained using the GBSBM model is compared with Clarke’s model. The results show that the rate of fading at the base station is lower than at the mobile and the reduction in the Doppler spread at the base station is dependent on the direction of motion of the mobile with respect to the base station and the radius of the the scattering circle.

Overview Of Spatial Channel Models For Antenna Array Communication Systems

Jeffrey H. Reed, Ertel, R.B.; Cardieri, P.; Sowerby, K.W.; Rappaport, T.S.
Journal Paper Personal Communications, IEEE , vol.5, no.1, pp.10,22, Feb 1998


Spatial antenna diversity has been important in improving the radio link between wireless users. Historically, microscopic antenna diversity has been used to reduce the fading seen by a radio receiver, whereas macroscopic diversity provides multiple listening posts to ensure that mobile communication links remain intact over a wide geographic area. In later years, the concepts of spatial diversity have been expanded to build foundations for emerging technologies, such as smart (adaptive) antennas and position location systems. Smart antennas hold great promise for increasing the capacity of wireless communications because they radiate and receive energy only in the intended directions, thereby greatly reducing interference. To properly design, analyze, and implement smart antennas and to exploit spatial processing in emerging wireless systems, accurate radio channel models that incorporate spatial characteristics are necessary. In this tutorial, we review the key concepts in spatial channel modeling and present emerging approaches. We also review the research issues in developing and using spatial channel models for adaptive antennas

Performance Analysis of the Spectral Correlation Discriminator Array

Jeffrey H. Reed, Paul Petrus
Journal Paper IEEE Pers. Commun., pp. 10-22, February 1998


Mobile communications suffer from cochannel interference, adjacent channel interference and fading. The cell capacity or the number of users per cell is limited by the interference. In this paper we analyze a new blind adaptive array structure called the spectral correlation discriminator array (SCDA), designed to reject cochannel interference for advanced mobile phone service (AMPS) signals. The blind adaptive array exploits the spectral redundancy in the AMPS signals which arises due to the presence of the supervisory audio tone (SAT). SCDA is shown to provide an improvement of 25–30 dB in signal-to-interference plus noise ratio (SINR) in static multipath channels and 10–15 dB improvement of SINR in Rayleigh fading channels. The SCDA is compared to the least squares constant modulus array (LSCMA) and is shown to have better signal selectivity properties. The reduction in interference power can significantly reduce the frequency reuse factor.

Despread-Respread Multi-Target Constant Modulus Array For CDMA Systems

Jeffrey H. Reed, Zhigang Rong; Petrus, P.; Rappaport, T.S.
Journal PaperCommunications Letters, IEEE , vol.1, no.4, pp.114,116, July 1997


We apply the concept of the despread-respread (DR) algorithm to multi-target arrays for code-division multiple-access (CDMA) signals, the despread-respread algorithm exploits the knowledge of the pseudo-noise (PN) code used to generate the transmitted CDMA signal. We extend the DR algorithm to not only exploit the knowledge of the PN code but also to preserve the constant modulus property of the signal. This new algorithm is called the least squares despread respread multi-target constant modulus array (LS-DRMTCMA). LS-DRMTCMA performs better than the least squares despread respread multi-target array (LS-DTMTA), least squares multi-target constant modulus array (LS-MTCMA), and steepest descent multi-target decision directed array (SD-MTDDA).

Interference Rejection In Digital Wireless Communications

Jeffrey H. Reed, Laster, J.D
Journal PaperSignal Processing Magazine, IEEE, vol.14, no.3, pp.37,62, May 1997


The growth in wireless communications necessitates more efficient utilization of spectrum. The increased sharing of spectrum translates into a higher likelihood of users interfering with one another. Interference rejection techniques allow a high capacity of users within the available spectrum. This overview comprises a literature review of published papers pertaining to single-channel adaptive interference rejection in digital wireless dating primarily from 1980 to the present. Though previous overviews are referenced and summarized, the focus is on advances not covered by previous overviews (consequently, some papers are included that predate 1980 because they are not covered in previous overviews). An organizational chart (divided into spread spectrum and nonspread spectrum techniques) is shown which outlines the types of techniques covered. Interference rejection is important for several reasons. Cellular capacity is inherently interference limited, particularly by co-channel interference (CCI) and adjacent-channel interference (ACI). One solution to combat CCI and ACI is to split cells and decrease the power, but cell-splitting is expensive. Interference-rejection techniques often represent a less expensive alternative to cell-splitting. In addition, as newer communication technologies supersede older technologies, interference-rejection techniques are important in helping to facilitate compatibility during transitions between the old and new technologies

Effects Of Directional Antennas At The Base Station On The Doppler Spectrum

Jeffrey H. Reed, Laster, J.D
Journal Paper Signal Processing Magazine, IEEE, vol.14, no.3, pp.37,62, May 1997


The growth in wireless communications necessitates more efficient utilization of spectrum. The increased sharing of spectrum translates into a higher likelihood of users interfering with one another. Interference rejection techniques allow a high capacity of users within the available spectrum. This overview comprises a literature review of published papers pertaining to single-channel adaptive interference rejection in digital wireless dating primarily from 1980 to the present. Though previous overviews are referenced and summarized, the focus is on advances not covered by previous overviews (consequently, some papers are included that predate 1980 because they are not covered in previous overviews). An organizational chart (divided into spread spectrum and nonspread spectrum techniques) is shown which outlines the types of techniques covered. Interference rejection is important for several reasons. Cellular capacity is inherently interference limited, particularly by co-channel interference (CCI) and adjacent-channel interference (ACI). One solution to combat CCI and ACI is to split cells and decrease the power, but cell-splitting is expensive. Interference-rejection techniques often represent a less expensive alternative to cell-splitting. In addition, as newer communication technologies supersede older technologies, interference-rejection techniques are important in helping to facilitate compatibility during transitions between the old and new technologies.

Subspace Based PN Code Sequence Estimation For Direct Sequence Signals Simplified Hebb Rule

Jeffrey H. Reed, F. Dominique,
Journal Paper Signal Processing Magazine, IEEE, vol.14, no.3, pp.37,62, May 1997


It is known that a tapped delay line FIR filter adapted by the constrained Hebbian rule can blindly estimate the code sequence of a direct sequence (DS) signal, provided that the estimation is symbol synchronous. A modification is proposed to the existing Hebb based blind sequence estimator to reduce the number of computations required; simulation results are presented.

Estimating Spectral Correlations Using The Least Mean Square Algorithm

Jeffrey H. Reed, F. Dominique,
Journal PaperElectronics Letters , vol.33, no.3, pp.182,184, 30 Jan 1997


Introduction: The LMS algorithm has found widespread use [1] in adaptive filtering, noise cancellation, signal enhancement, etc. This Letter adds a new application of the LMS algorithm in estimating the spectral correlations in a cyclostationary signal. Spectral correla- tion analysis is a useful tool for the detection and characterisation of cyclostationary signals. Spectral correlation arises from the underly- ing periodicities found in communication signals such as baud/chip- ping rates and carrier frequencies.

A Despread Data Rate Update Multi-Target Adaptive Array For CDMA Signals

Jeffrey H. Reed, F. Dominique,
Journal Paper IEE Electron. Lett., pp. 119-121, January 1997


The authors examine the performance of a blind adaptive array algorithm for spatial filtering of code division multiple access (CDMA) signals. The algorithm is based on decision direction and takes advantage of the processing gain of the CDMA system to give improved performance over a non-despread architecture.

Simple PN Code Sequence Estimation And Synchronisation Technique Using The Constrained Hebbian Rule

Jeffrey H. Reed, Agee, B.G.; Kleinman, R.J
Journal Paper IEEE Trans. Commun., pp. 1527-1536, November, 1996


A new technique for soft synchronization of direct-sequence spread-spectrum (DSSS) signals is presented. The technique, referred to as the dominant mode despreading (DMDS) algorithm, exploits the eigenstructure of a frequency-channelized DSSS signal to estimate the spreading code and underlying message sequence of the signal. Unlike other despreading techniques, the estimate of the code and data improves steadily with the number of code repeats. The technique is applicable to arbitrary spreading codes and message sequences and can operate in environments containing arbitrary levels of white background noise, and for signals with arbitrary unknown timing phase or carrier frequency offset. The technique requires the DSSS signal to have a constant-modulus spreading code and unrelated message and code-repeat rates. This paper introduces the basic technique, theoretically analyzes the algorithm to prove convergence under infinite time-average conditions, and demonstrates the algorithm via computer simulation for a single DSSS signal received in the presence of white Gaussian noise.

Position Location Using Wireless Communications On Highways Of The Future

Jeffrey H. Reed, Rappaport, T.S.; Reed, J.; Woerner, B.D
Journal PaperIEEE Trans. Commun., pp. 1527-1536, November, 1996


With the advances in wireless communications and low-power electronics, accurate position location may now be accomplished by a number of techniques which involve commercial wireless services. Emerging position location systems, when used in conjunction with mobile communications services, will lead to enhanced public safety and revolutionary products and services. The fundamental technical challenges and business motivations behind wireless position location systems are described, and promising techniques for solving the practical position location problem are treated

A Robust Frequency Hop Synchronization Algorithm

Jeffrey H. Reed, F Dominique
Journal PaperIEE Electron. Lett., vol. 32, no. 16, pp. 1450-1451, August 1996.


The performance of conventional frequency hop (FH) synchronisation algorithms degrades in the presence of fading. Recovery times can be quite long for these classical synchronisation techniques. The authors describe a novel algorithm that makes use of past state information about the synchronisation to maintain FH synchronisation even in the presence of fading, narrowband interference and other channel distortion.

Evaluation Of A Soft Synchronization Technique For DS/SS Signals

Jeffrey H. Reed, Rappaport, T.S.; Reed, J.; Woerner, B.D
Journal PaperSelected Areas in Communications, IEEE Journal on , vol.14, no.8, pp.1643,1652, Oct 1996


Soft synchronization of direct-sequence spread-spectrum (DS/SS) signals introduces the capability of despreading with a continuously improving estimate of the spreading code. The soft synchronization technique presented and demonstrated in this paper exploits the eigenstructure of a frequency-channelized DS/SS signal to estimate the code. The estimate improves steadily as more data is collected, resulting in an improved estimate of the message signal. This allows commencement of despreading at an early stage when the code-estimate is still imperfect. Under infinite-time average assumptions a perfect code estimate can be obtained when the signal is received in arbitrary levels of white background noise. This paper demonstrates the synchronization performance of the technique through simulations under finite time-average conditions for environments with fading, multipath, and multi-user interference. The soft synchronization capability is demonstrated. Results show that the technique can remove frequency offsets on the received signal that are integer multiples of the code repeat rate, and that its performance is not degraded by multipath.

An Optimal Receiver Implemented Using A Time-Dependent Adaptive Filter

Jeffrey H. Reed, N. Yuen, and T. C. Hsia
Journal Paper IEEE Trans. Commun., vol. 43, no. 2/3/4, pp. 187-190, February-March-April 1995


The optimal time-dependent receiver (OTDR) is presented and its performance is compared to that of the matched filter receiver. The OTDR, a time-dependent adaptive filter, is shown through simulation to be superior to the matched filter for signals corrupted by cyclostationary interference because it exploits statistical periodicities of the interference

Simulation Issues For Future Wireless Modems

Jeffrey H. Reed, B. D. Woerner, and T. S. Rappaport
Journal Paper IEEE Commun. Mag., vol. 32, no. 7, pp. 42-53, July 1994


Mobile communication systems present several design challenges that stem from the mobility of users throughout the system and the time-varying multipath channel and interference. To address these challenges, future wireless modems will rely on performance enhancing techniques such as adaptive antennas, DSP-based interference rejection techniques, and real-time signal processing for capacity improvement. The authors present an overview of key simulation issues for wireless communications systems. First, the burst error characteristics of the mobile channel require the selection of appropriate performance measures. Second, accurate simulations require realistic channel models that include the effects of attenuation, multipath propagation, noise, and interference. Third, link-level simulation of wireless systems requires attention to details of system implementation including the effects of nonlinearities. Finally, efficient simulation of CDMA systems may require a combination of analytic and simulation techniques.

Interference Rejection Using The Generalized Constant Modulus Algorithm And The Hybrid CMA/SCD

Jeffrey H. Reed, R. Mendoza, T. C. Hsia, and B. G. Agee
Journal Paper IEEE Trans. Signal Processing, pp. 2108-2111, vol. 39, no. 9, September 1991.


Two new blind adaptive filtering algorithms for interference rejection using time-dependent filtering structures are presented. The time-dependent structure allows the adaptive filter to outperform the conventional adaptive filter implemented with a time-independent structure for filtering of cyclostationary communication signals. At the same time, the blind adaption algorithms allow the filters to operate without the use of an external training signal. The first algorithm applies the CMA to an unconstrained time-dependent filtering structure. The second algorithm applies the CMA to a spectral correlation discriminator, which is constrained to select signals with unique spectral correlation characteristics. Using computer simulations, it is shown that the blind time-dependent filtering algorithms can provide mean-square errors (MSEs) and bit error rates (BERs) that are significantly lower than the MSEs and BERs provided using conventional time-independent adaptive filters. It is also shown that these processors can outperform the nonblind training-sequence directed time-independent adaptive filter.

Application Of Adaptive Short-term Correlation Algorithms To Interference Rejection

Jeffrey H. Reed, Hsia, T.C
Journal Paper Circuits, Systems and Computers, 1985. Nineteeth Asilomar Conference on , vol., no., pp.441,445, 6-8 Nov. 1985


Two new adaptive filtering techniques are presented for enhancing and spearating narrow-band signals with different durations. The two techniques are called intermittent Signal Enhacement.

A Technique For Sorting And Detecting Signals In Interference

Jeffrey H. Reed, Hsia, T.C
Journal Paper IEEE Military Communications Conference, San Diego, CA, Oct. 23-26, 1988, Conference Record. Volume 2 (A89-24027 08-32). New York,


An adaptive filtering technique spectra correlation discrimination is proposed that provides a means of separating signals on the basis of their spectral correlation characteristics, as determined by the signal parameters (modulation type, band rate, chip rate, hop rate, etc.). A conceptual description and a theoretical analysis of the spectral correlation discriminator are given, and computer simulations are presented to demonstrate its utility.

Practical Issues for Spectrum Management With Cognitive Radios

Jeffrey H. Reed, Stephen M. Dudley,Marc Lichtman, Xiaofu Ma,Abid Ullah, Munawwar M. Sohul, Taeyoung Yang, William Christopher Headley, Eyosias Yoseph Imana, Mahi Abdelbar, Aditya Padaki
Journal Paper Proceedings of the IEEE, Volume: 102, Issue: 3, Page: 242


The policy of permanently assigning a frequency band to a single application has led to extremely low utilization of the available spectrum. Cognitive radio, with its ability to be both intelligent and frequency agile, is thought to be one of the prime contenders to provide the necessary capabilities needed for dynamic spectrum access systems. With this in mind, this paper discusses the practical issues inherent to the deployment of spectrum management systems utilizing cognitive radios.

Maximum Transmit Power and GAA Channel Assignments on CBRS 3.5 GHz Spectrum Sharing Framework

Masoud Olfat, Jeffrey Reed, Kurt Schaubach
Journal Paper IEEE COMSOC TCCN Communications, Vol. 1, No. 1, December 2015


This paper describes the Citizen Broadband Radio Servce (CRBS) framework for 3.5 GHz spectrum sharing and some of the concerns that industry has raised about the FCC Report and Order that defines this service. Specifically, the transmit power limits proposed by FCC unnecessarily limits the efficient coverage in 3.5 GHz band and hence new power limits have been proposed by WinnForum members to address this issue.

SMAC: A Soft MAC to Reduce Control Overhead and Latency in CDMA based AMI Networks

Garlapati, Shravan; Kuruganti, Pnani Teja;, Buehrer, Michael R. Reed, Jeffrey
Journal Paper IEEE /ACM Transactions on Networking, August 2015


Abstract unavailable

Addressing a Neighboring-Channel Interference from High-Powered Radar

Eyosias Imana, Jeffrey Reed,
Journal Paper IEEE Transactions on Vehicular Technology, April 2015


Abstract unavailable

A Communications Jamming Taxonomy

Marc Lichtman, T. Charles Clancy, Jeffrey Reed,
Journal Paper IEEE Security and Privacy, April 2015


Abstract unavailable