CAREER: Cooperative Communication Systems: Resource Allocation, Self-Organization, and Synchronization

通过无线信道进行可靠通信的关键是多样性。在用于实现分集的各种方法中，通过使用多个发射和/或接收天线的空间分集特别有吸引力，因为它不需要额外的带宽或传输速率的损失。然而，空间分集确实需要使用多个天线，这些天线必须至少相隔几个波长才能有效。这种物理限制在许多情况下阻碍了空间分集的使用，但最近，研究人员在多用户通信系统的背景下考虑了这个问题，其中可能存在多个源和/或目的地，每个只有一个天线。在这些类型的系统中，通信节点可以形成“伙伴关系”，实现一种新的空间多样性：“用户合作多样性”。伙伴关系中的节点将其天线资源集中在一起形成虚拟天线阵列，无需“真实”天线阵列即可实现空间分集的许多好处。虽然用户合作分集可以为只能访问单个天线的设备提供天线阵列的许多优点，但其实现问题与天线阵列的实现问题明显不同。与传统的天线阵列不同，合作伙伴关系中的节点至少是半自治的，因为它们每个节点通常都有自己的本地资源、服务质量需求和定时参考。本项目围绕合作性多用户通信系统中节点固有的自主性所产生的问题：如何发起和维持合作伙伴关系，如何在合作伙伴关系中优化分配资源，以及如何同步合作节点。

The key to reliable communications over wireless channels is diversity. Of the various methods used to achieve diversity, spatial diversity through the use of multiple transmit and/or receive antennas is particularly attractive in that it does not require additional bandwidth or loss of transmission rate. Spatial diversity does, however, require the use of multiple antennas which must be separated by at least a few wavelengths in order to be effective. This physical constraint precludes the use of spatial diversity in many scenarios, but recently, researchers considered this problem in the context of multiuser communication systems in which there may be multiple sources and/or destinations each with only a single antenna. In these types of systems, communicating nodes can form "partnerships" to achieve a new kind of spatial diversity: "user cooperation diversity". Nodes in a partnership pool their antenna resources to form a virtual antenna array and many of the benefits of spatial diversity are achieved without the need for a "real" antenna array.While user cooperation diversity can provide many of the advantages of antenna arrays to devices that would otherwise only have access to a single antenna, the implementation issues are significantly different than those of antenna arrays. Unlike a traditional antenna array, the nodes in a cooperative partnership are at least semi-autonomous in the sense that they each typically have their own local resources, quality-of-service requirements, and timing references. This project is centered around the questions created by the inherent autonomy of nodes in cooperative multiuser communication systems: how to initiate and maintain cooperative partnerships, how to optimally allocate resources in cooperative partnerships, and how to synchronize cooperating nodes.