Implementation of a reconfiguration algorithm for cognitive radio

Abstract — In wireless communication systems, advances in computer architecture and processor technology have made it possible for functionality previously implemented in hardware to become tunable via software. These software-defined radios (SDRs) will allow new radio devices to sense, reason, and adapt to changes in the RF environment and/or application requirements making them cognitive radios (CRs). Fully exploiting the flexibil-ity of cognitive radios, however, requires an understanding of how different permutations of radio parameters impact application-specific performance metrics. For example, while a CR that is not meeting its bit loss goals could change its operating frequency to reduce the impact of interference. However, the added overhead from changing frequencies could result in an application failing its latency requirements. This paper describes one such method for configuring a cognitive radio and demonstrates the efficacy of the technique on both a simulation based analysis and an in situ evaluation on a software radio platform. Our reconfiguration system quantifies the influence of radio parameters such as frequency agility, bit rate, and transmit power for adapting communication at the application, medium access control, and physical layers. The method calls for exhaustively evaluating a set of CR’s configurations against a variety of performance metrics and applying statistical processes to determine which settings will have the most significant impact on performance. Once this is done, the experimental results are then used to inform the design of an algorithm that is able to reconfigure to meet performance goals. We show that while the method for deriving the model functions consistently across both the simulation and implementation platforms, the different evaluation platforms emphasize different parameters when controlling the radios. “The views expressed in this article are those of the author and do not reflect the official policy or position of the United States Air Force, Department of Defense, or the U.S. Government.