EARS: Collaborative Research: Full-Duplex Cognitive Radio: A New Design Paradigm for Enhancing Spectrum Usage

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With the rapid growth of demand for ever-increasing data rate, spectrum resources have become more and more scarce. As a promising technique to increase the efficiency of the spectrum utilization, cognitive radio (CR) technique has the great potential to meet such a requirement by allowing unlicensed users to coexist in licensed bands. In conventional CR systems, the spectrum sensing is performed at the beginning of each time slot before the data transmission. This unfortunately results in two major problems: 1) transmission time reduction due to sensing, and 2) sensing accuracy impairment due to data transmission. To tackle these problems, a new design for future CR is proposed by exploring the full-duplex (FD) techniques to achieve the simultaneous spectrum sensing and data transmission. The aim of this proposal is to transform the promising conceptual framework into the practical wireless network design by addressing a diverse set of transformative challenges such as protocol design and theoretical analysis. The educational plan will provide interdisciplinary training for graduate and undergraduate students. Active student involvement is ensured via mentoring, research involvement, and participation in testbed development. Outreach events targeting high school students, particularly women and minority, will be organized. Broad dissemination is guaranteed via publications, tutorials, workshops, and online tools.The proposed research aims at laying the foundations of FD CR networks via an interdisciplinary framework that synergistically marries concepts from signal processing, wireless communications, networking, and RF hardware design to yield several innovations: 1. With multiple input and multiple output (MIMO) FD radios, secondary users can simultaneously sense and access the vacant spectrum, and thus, significantly improve sensing performances and meanwhile increase data transmission efficiency. The research issue is using MIMO to jointly considering primary user receivers and FD self-interference. 2. Classic CR networks using listen-before-talk, while FD enable listen-and-talk, which can significantly improve the network performances. The research issues are to investigate the tradeoffs. 3. The classical multiple random access protocol is based on carrier sensing multiple access/collision avoidance (CSMA/CA), while FD enables collision detection (CSMA/CD). The research issue is to analyze the performances under self interference. 4. The proposed FD network protocols will be tested using WARP boards equipped with MIMO technology.