A High-Performance Wideband Receiver for Cognitive Radio

智力优势：认知无线电通过感知可用频段并以机会主义的方式进行通信，使稀缺的无线电频谱得到有效利用。虽然在文献中已经报道了大量的工作，使得能够动态地使用这些未被充分利用的频谱资源，但认知无线电的基本假设是可获得灵活而高效的宽带接收器。然而，设计这样的接收器是具有挑战性的。具体问题是接收器通带较宽造成的互调和谐波失真，需要宽调谐范围的频率合成器来跨越感兴趣的频段，以及使用耗电的高速ADC来缩短检测时间。在所提出的研究中，宽带接收机中的谐波混合过程被视为通信中的多用户接入系统。这一观点允许利用多用户检测理论的现有工作来开发技术，以克服许多实现挑战。为了充分实现所提出的方法的好处，将继续进行几个研究任务，包括开发可扩展的接收器体系结构，探索多相/多频时钟的模拟合并方法以在数字均衡后最大化性能，以及设计利用混合过程结构的稳健和高性能的数字均衡器。此外，本研究还将通过在硅片上实现宽带接收机的方法来验证该方法的可行性和优越性。在清楚了解各种设计方案以及相应的性能和实现复杂性权衡的基础上，将开发一个完整的设计框架。广泛影响：拟议的研究应有助于实现高性能认知无线电，这已成为有效利用稀缺无线电电磁频谱的一种有前途的方法。此外，这项研究中提出的概念广泛适用于许多现有和新兴的宽带系统，例如多标准/多频段无线电和软件定义无线电。这些原理也可以应用于雷达系统和传感器网络中的非通信应用。上述研究计划与教育计划相结合，描述了拟议的研究将如何帮助培养研究生和本科生。拟议研究的多学科性质将扩大学生对技术的理解，PI认为这对下一代工程师至关重要。该提案还包括改善本科生和代表性不足群体成员的参与程度的计划。

Intellectual Merit:Cognitive radio enables efficient use of the scarce radio spectrum by sensing available bands and communicating in an opportunistic manner. Although significant work has been reported in the literature that enables dynamic use of these under-utilized spectrum resources, the underlying assumption in cognitive radio is the availability of a flexible and efficient wideband receiver. Designing such a receiver, however, is challenging. The specific problems are the inter-modulation and harmonic distortion caused by the wide passband of the receiver, the need for a wide tuning range frequency synthesizer to span the frequency band of interest, and the use of power-hungry high-speed ADCs to reduce sensing time. In the proposed research, the harmonic mixing process in wideband receivers is viewed as a multi-user access system in communications. This perspective allows leveraging on existing work on multi-user detection theory to develop techniques to overcome many of the implementation challenges. To fully realize the benefits of the proposed approach, several research tasks will be pursued, including developing a scalable receiver architecture, exploring analog combining methods of multi-phase/multi-frequency clocks to maximize performance after digital equalization, and devising a robust and high-performance digital equalizer that exploits the structure of the mixing process. Furthermore, this research will demonstrate the feasibility and the advantages of the proposed approach to wideband receiver design by realizing it on silicon. A complete design framework will be developed based on a clear understanding of various design options and the corresponding tradeoffs in performance and implementation complexity.Broader Impact:The proposed research should help realize a high-performance cognitive radio, which has emerged as a promising approach to efficiently exploit the scarce radio electromagnetic spectrum. In addition, the concepts developed in this research are broadly applicable to many existing and emerging wideband systems such as in multi-standard/multi-band radios and software defined radios. The principles can also be applied to non-communication applications in radar systems and sensor networks. The above research plan is coupled with an education plan that describes how the proposed research will help train both graduate and undergraduate students. The multi-disciplinary nature of the proposed research will broaden the students technical understanding, which the PI believes is essential for next generation of engineers. The proposal also includes plans to improve the participation of undergraduate students and members of under-represented groups.