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

无线网络中超宽带(UWB)通信的高级信号处理遵循联邦通信委员会2002年2月的命令，超宽带(UWB)通信技术已成为无线网络中极高数据速率应用的领先标准。该技术将允许多个设备以非常高的速率和低功耗进行无线连接。UWB将允许在设备之间以可能达到480 Mbps的速率传输视频、音频和其他数据流量。例如，UWB可以将实时视频内容从PC或消费电子设备(如便携式摄像机、DVD播放器或个人录像机)传输到平板HDTV显示器，而不需要电线。为了使这项技术得到广泛采用，有必要保持UWB设备的低成本。一个主要的挑战来自模拟处理过程中由于制造缺陷而引入的信号失真。由于更高的硅集成度、更低的功耗、更大的带宽和更高的载波频率，这些失真的影响将在未来的高性能无线网络中复杂化。至少有两种策略可以解决这一难题。一种策略通常成本高昂，依赖于建造更可靠的前端无线电。第二种策略是通过在数字领域使用先进的信号处理和补偿算法来模拟和消除信号失真，这也是本提案的目标之一。本研究提出了一种系统的方法来建模失真效应，在接收机设计中利用失真模型，开发能够抵消失真影响并改善UWB设备射程的增强型ofdm接收机，研究了性能的理论极限，并在FPGA测试平台上实现和测试了所开发的算法。(1)利用先进的数字域信号处理算法，发展超宽带设备的失真模型和失真抵消技术。(2)通过联合解决提高距离、改进信道估计和失真补偿等问题，开发适用于超宽带通信的增强型OFDM接收机。(3)将研制的失真接收机用于单用户和多用户(空时编码)通信场景。(4)研究系统性能的理论极限和失真对系统性能的影响。(5)使用所开发的算法在FPGA上进行UWB系统的概念验证实现，以研究改进性能的模型和算法。PI和他的研究团队在高级信号处理、通信和自适应系统设计的不同方面拥有丰富的研究经验。拟议的研究活动在几个方面具有创造性：(1)它认识到有必要解决模拟处理引入的信号失真，以此作为保持UWB设备成本较低的一步。(2)它认识到在数字域中消除失真的重要性，而不是在模拟域中。(3)研究了主要的失真来源(包括智商不平衡、相位噪声、发射机和接收机的非线性)对算法开发和性能的影响。(4)它解决了主要的性能障碍，例如为了合并失真模型而增强的信道估计、基于失真稳健的基于ofdm的SISO和MIMO(空时编码)通信的设计，以及由于UWB设备有限的发射功率而需要改善其射程。(5)注意算法复杂度和硬件实现之间的复杂平衡。拟议研究领域的更广泛影响如下：(1)它使前景光明的超宽带技术以较低的成本得到广泛传播，从而对国家的信息技术基础设施产生重大影响。(2)它为PC外围设备、消费电子产品、家庭网络和移动设备的超高速无线网络的发展做出了贡献，数据速率可能达到480 Mbps。(3)在与未来通信系统基本相关的领域对研究生和本科生进行培训。(4)研究结果将在网上广泛传播，并通过档案期刊和会议记录中的出版物广泛传播，还将通过硬件测试演示来广泛传播。

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