Advanced Signal Processing for Ultra-Wide-Band (UWB) Communications in Wireless Networks

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Advanced Signal Processing for Ultra-Wide-Band (UWB) Communications in Wireless NetworksFollowing the February 2002 order by the Federal Communications Commission, ultra-wide-band (UWB) communications technology has emerged as the leading standard for very high datarate applications in wireless networks. The technology will allow the wireless connection of multipledevices at very high rates and at low power consumption. UWB will allow the transmission ofvideo, audio, and other data traffic among devices at rates that may reach 480Mbps. For example,UWB could stream real-time video content from a PC or a consumer electronics device, such asa camcorder, a DVD player or a personal video recorder, to a flat-screen HDTV display withoutthe need for wires. In order for this technology to become widely adopted it is necessary tomaintain the costs of UWB devices low. A major challenge arises from the signal distortionsthat are introduced during the analog processing as a result of manufacturing imperfections. Theeffects of such distortions will be compounded in future high-performance wireless networks dueto the higher silicon integration, lower power consumption, larger bandwidth, and higher carrierfrequency. There are at least two strategies to address this diffculty. One strategy is generallycostly and relies on building more reliable front-end radios. The second strategy, which is one ofthe objectives of this proposal, is to model and cancel signal distortions by using advanced signalprocessing and compensation algorithms in the digital domain. This research proposes a systematicway for modeling distortion effects, exploiting the distortion models in receiver design, developingenhanced OFDM receivers that counter-balance the effects of distortions and that improve therange of UWB devices, investigating theoretical limits of performance, and also implementing andtesting the developed algorithms on an FPGA testbed.Objectives. (1) Develop distortion models and distortion cancellation techniques for UWB de-vices by using advanced signal processing algorithms in the digital domain. (2) Develop enhancedOFDM receivers for UWB communications by jointly addressing the issues of improved range,improved channel estimation, and distortion compensation. (3) Use the developed distortion can-cellation receivers for both single user and multi-user (space-time coded) communications scenarios.(4) Investigate theoretical limits of performance and effects of distortion on system performance. (5)Pursue a proof-of-concept implementation of a UWB system on an FPGA by using the developedalgorithms in order to investigate the models and the algorithms for improved performance.Intellectual Merit of the Proposed Activity. The PI and his research group have extensive researchexperience on different aspects of advanced signal processing, communications, and adaptive systemdesign. The proposed research activity is creative in several respects: (1) It recognizes the need toaddress signal distortions introduced by analog processing as a step towards maintaining the costof UWB devices low. (2) It recognizes the importance of cancelling distortion in the digital domain,as opposed to the analog domain. (3) It studies the effects of major sources of distortion (includingIQ imbalances, phase noise, and transmitter and receiver nonlinearities) on algorithm developmentand performance. (4) It addresses major performance hurdles such as enhanced channel estimationin order to incorporate distortion models, the design of distortion-robust OFDM-based SISO andMIMO (space-time coded) communications, and the need for improved range for UWB devices dueto their limited transmit power. (5) It pays attention to the intricate balance between algorithmcomplexity and hardware implementation.Broader Impacts of the Proposed Activity. The broader impacts of the proposed research areas follows: (1) It has significant implications on the information technology infrastructure of thenation by making the promising UWB technology widely spread at lower costs. (2) It contributesto the development of ultra-high-speed wireless networks for PC peripherals, consumer electronics,home networking, and mobile devices at data rates that may reach 480Mbps. (3) It trains bothgraduate and undergraduate students in an area of fundamental relevance to future communicationssystems. (4) The results of the research will be widely disseminated online and via publications inarchival journals and conference proceedings, and also via demonstrations of the hardware testbed.A-1