CAREER: Opportunistic Communication: A Design Paradigm for Wireless Systems

对无线通信服务的需求已经比分配的附加资源（诸如带宽）增长得快得多。除了有限的可用带宽之外，无线系统设计人员还必须应对有线网络中不常见的几个独特挑战，例如传输和用户特定时间和频率变化信道引起的干扰。通过物理层和网络层的和谐设计来管理有限的资源是无线系统设计中的一个核心问题，也是一个非常相关的问题。在过去的十年里，针对这个问题的密集研究活动可以大致分为两部分：物理层工作主要集中在点对点 通信层和网络层使用物理层的抽象来进行资源分配。此外，无线系统的工程设计在很大程度上集中在使各个点对点链路可靠和使用物理层的适当模型开发网络层。 这个项目 从物理层的基本观点来看待无线网络通信问题，并深入了解物理层和网络层的新颖设计技术，从而显著提高了整体系统容量。一个新颖的观点是多用户分集， 一种固有的多样性形式 无线网络。在具有许多用户的系统中，其信道独立地变化，可能存在其信道在任何一个时间接近其峰值的用户。通过只向具有最佳信道的用户调度传输，利用了多用户分集增益。 这种形式的“机会主义沟通”提供了一个急剧的推动力 到系统吞吐量。通过的透镜 多用户分集， 通道波动是优选的，与 点到点的通信视图。本项目对 多用户多样性的作用：人为诱导和利用多样性的计划。 研究的其他具体问题包括多天线下行链路（广播）信道和ad hoc网络的基本观点 模型教学是这个项目的一个组成部分， 通过四个课程的开发。

Demand for wireless communication services has been growing much faster than additional resources (such as bandwidth) are allocated. Besides scarce available bandwidth, wireless system designers have to deal with several unique challenges, not commonly found in wireline networks, such as interference caused by transmissions and user specific time and frequency varying channels. Managing the limited resources through a harmonious design of the physical and networking layers is a central problem in the design of wireless systems and a very relevant one. The intense research activity over the past decade addressing this issue can be roughly dichotomized into two parts: the physical layer work focusing mostly on point to point communication and the networking layer work of resource allocation using an abstraction of the physical layer. Further, engineering design of wireless systems, for the most part, has centered around making individual point to point links reliable and developing a networking layer using an appropriate model of the physical layer. This project takes a fundamental physical layer view of the wireless network communication problems and sheds insight into novel design techniques at both the physical and the networking layer, yielding a significant boost to the overall system capacity. One novel viewpoint is multiuser diversity, a form of diversity inherent in a wireless network. In a system with many users whose channels vary independently, there is likely to be a user whose channel is near its peak at any one time. By scheduling transmissions only to users with the best channel, multiuser diversity gain is harnessed. This form of "opportunistic communication" provides a sharp boost to the system throughput. Through the lens of multiuser diversity, channel fluctuations are preferable, in sharp contrast to the point to point communication view. This project conducts a systematic study of the role of multiuser diversity: schemes to artificially induce and harness it. Other specific problems studied include a fundamental view of the multiple antenna downlink (broadcast) channel and an ad hoc networking model. Teaching is an integral part of this project and is partly carried out through the development of four courses.