Blocker-Tolerant Ultra-wideband Cognitive Spectrum Sensor
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This EARS (Enhancing Access to the Radio Spectrum) program was founded in response to the 2010 Presidential Memorandum on Unleashing the Wireless Broadband Revolution mandated by Congress as part of the National Broadband Plan. It was referenced in 2010 State of the Union and later on the Middle Class Tax Relief and Job Creation Act of 2012 (More than 1/3 of the bill deals with radio spectrum), the PCAST 2012 Report [President''s Council of Advisors on Science and Technology] (which calls for vastly increased use of spectrum sharing) and the 2013 Presidential memo (Expanding America''s Leadership in Wireless Innovation). The aim of this program is to identify bold new concepts with the potential to contribute to significant improvements in the efficiency of radio spectrum utilization, protection of passive sensing services, and in the ability for traditionally underserved Americans to benefit from current and future wireless-enabled goods and services. The impact is large on the economics of the Nation as seen on the last FCC bidding of 65MHz of the spectrum for over $45 billion early in 2015. It will enable access to science, engineering, industry, civilian and military users of the radio frequency (RF) spectrum. The objective of this proposal is to provide an innovative, secure and resilient spectrum-sharing technology to improve wireless broadband communications for the consumer electronics sector and enhance spectrum availability for critical government services. The problem of sensing, estimating and detecting several gigahertz of a spectrum bandwidth populated by a number of unidentified (as to location) user''s signals has unleashed a highly interdisciplinary research endeavor. This problem a crosscutting problem in all these disciplines: signal processing, communications, systems, and circuit problem. The fundamental challenge is to estimate unoccupied spectrum regions that are surrounded by potentially large signal blockers. The combined bandwidth, linearity and dynamic range requirements of these unoccupied regions exceed that found in state-of-art of radio receivers by several times. Cognitive radio technology has been proposed for such purposes over the last decade; however, its development has run into bottlenecks due to several technological challenges. This proposal addresses the need for a more efficient coexistence of weak opportunistic secondary user signals with mixed strong/weak primary signals that are currently used for commercial applications, public safety, homeland security, and national defense. This proposal aims at designing and optimizing novel and innovative cognitive multi-channel spectrum sensors, enabling smart and dynamic next-generation wireless communication systems, which will coexist harmonically with other broadband systems over the same frequency bands. To accomplish this goal, the proposed research objectives are: (1) coarse frequency estimation of strong primary signal blockers that interfere with the estimation and detection of weaker primary signals and spectrum holes; (2) strong blocker removal system in the radio frequency (RF) and analog domain to filter out the selected channel for reliable determination of opportunistic communications; (3) novel signal processing techniques based on locally most powerful (LMP) detectors for the estimation and detection of weak primary signals and spectrum holes.