NeTS-WN: Opportunistic Bandwidth Sharing Using MIMO: Beyond Time and Frequency

由于最近无线服务和网络的成功，以及对无线服务和网络的爆炸性需求，预计带宽资源将出现短缺。这种预期的短缺与其说是因为带宽的稀缺，不如说是因为带宽的低效使用。在时间和频率维度上存在大量可供无线网络潜在利用的“机会”。因此，重要的是要开发一种有效和高效地利用这些机会的新方法。最近的技术进步使实现SDR(软件定义无线电)或智能无线电成为可能，与传统无线电不同，SDR可以以最低成本从一个频率切换到另一个频率，从而实现沿时间和频率维度的“机会主义”频谱接入。SDR为下一代无线网络提供了自适应和动态的多频段接入，但也带来了几个独特的跨层挑战。另一方面，新兴的MIMO(多输入多输出)技术在显著提高吞吐量、更好地抑制干扰和大幅节省能源方面具有巨大的潜力。SDR和MIMO一起形成了一个完整的手段，不仅可以实现时间和频率维度的机会性频谱接入(通过SDR)，还可以实现空间维度的机会性频谱接入(通过MIMO)。因此，本项目将：1.对配备MIMO的无线网络中可达到的最大吞吐量进行建模、表征和分析；2.为网络设计人员确定无线网络的最佳参数提供指导；3.开发利用MIMO可靠地支持和维护MIMO无线网络中的服务质量的创新技术；以及4.在我们目前正在用商用现成组件建造的具有多频段能力的无线试验台上通过模拟和实验来实施和评估所开发技术的性能。拟议研究的智力价值将是：(1)为用SDRS和MIMO等先进技术组件构建下一代无线网络奠定理论和实践基础；(2)为选择配备这些先进组件的无线网络的最佳参数提供设计指南；(3)解决带宽短缺问题，这是下一代无线网络的关键；以及(4)使下一代无线网络能够支持和维护多媒体应用的服务质量的创新技术。这项研究还将对以下方面产生更广泛的影响：(1)基础研究，通过为未来无线网络中遇到的挑战性问题提供基本解决方案；(2)监管机构，如FCC，通过为建立灵活高效的频谱政策提供经过严格验证的解决方案和指南；以及(3)通过研究、教学和学习的整合，特别是在学生课堂和自主学习项目中使用开发的解决方案及其在拟议的试验台上的实施，对本科和研究生教育产生更广泛的影响。

There is an expected shortage in bandwidth resources due to the recent success of, and hence the explosive demand for, wireless services and networks. This expected shortage is not so much due to the scarcity of bandwidth, but due to its inefficient use. There exist plenty of ``opportunities" available along time and frequency dimensions that wireless networks can potentially exploit. It is therefore important to develop a new way of exploiting these opportunities effectively and efficiently. Recent technological advances make it possible to realize SDRs (Software-Defined Radios) or smart radios that, unlike traditional radios, can switch from one frequency to another at minimum cost, thereby enabling ''opportunistic'' spectrum access along time and frequency dimensions. SDRs empower next-generation wireless networks with adaptive and dynamic multi-band access, but introduce several unique cross-layer challenges. On the other hand, the newly-emerging MIMO (Multiple-Input Multiple-Output) technology has great potential for significant throughput enhancements, better interference suppression, and substantial energy savings. SDRs and MIMOs together form a complete means of enabling opportunistic spectrum access along not only time and frequency dimensions (via SDR), but also space dimension (via MIMO). This project will, therefore,1. Model, characterize, and analyze the maximum achievable throughput in MIMO-equipped wireless networks;2. Derive guidelines for network designers to determine the optimal parameters of wireless networks;3. Develop innovative techniques that exploit MIMO to reliably support and maintain QoS in MIMO wireless networks; and4. Implement and evaluate the performance of the developed techniques via simulation and experimentation on a multi-band capable wireless testbed that we are currently building with commercial off-the-shelf components.The intellectual merit of the proposed research will be: (1) establishment of both theoretical and practical foundations for next-generation wireless networks to be built with advanced technological components such as SDRs and MIMO; (2) design guidelines for selecting the optimal parameters of wireless networks equipped with these advanced components; (3) solutions to the bandwidth-shortage problem, which is key to next-generation wireless networks; and (4) innovative techniques enabling next-generation wireless networks to support and maintain QoS of multimedia applications. This research will also make broader impacts on: (1) basic research by providing fundamental solutions to challenging problems to be encountered in future wireless networks; (2) regulatory bodies such as FCC by providing rigorously-proven solutions and guidelines for establishing flexible and efficient spectrum policies; and (3) undergraduate and graduate education via integration of research, teaching, and learning, especially the use of the developed solutions and their implementations on the proposed testbed in students' classes and independent study projects.