CIF: Medium: Collaborative Research: Distributed coherence: fundamental building blocks, system concepts, and experimental demonstration

在过去的二十年里，多天线无线系统的进步为无线通信吞吐量的极大增加打开了可能性。在现实世界的无线网络中，这些增长的实际实现受到尺寸和成本考虑的限制，这些因素限制了天线的数量，特别是对于移动设备。这项研究的目的是通过将多组无线收发信机汇集在一起，并像虚拟天线阵列一样协同工作，以分布式方式实现多天线技术的收益。虚拟阵列的概念通过将多天线系统的众多好处扩展到单天线设备的网络，对无线网络具有广泛的变革潜力。我们将在软件定义的无线电平台上试验并演示虚拟阵列技术，我们计划分享我们的实现作为可重复使用的构建块，以刺激技术过渡，并促进学术、开放源码软件社区和无线电爱好者社区之间的互动。虚拟阵列的元素具有未知的、通常是时变的几何结构，并由独立振荡器驱动，每个振荡器都具有随机漂移；主要的技术挑战是在存在这些影响的情况下保持阵列中的分布式一致性。虽然这是一个非常具有挑战性的问题，但最近的研究成果已经证明了虚拟阵列的可行性。该研究将为分布式相干奠定坚实的理论基础，并通过将该理论和技术应用于基于虚拟天线阵列的概念系统的跨层设计，为技术转移提供清晰的路径。具体地说，我们将开发一个用于跟踪和预测振荡器动力学和移动性的状态空间框架，以及适用于低成本单天线设备的大型分布式阵列的分布式发送和接收的可扩展体系结构。我们还将确定虚拟阵列的基本权衡和扩展规律。我们将把理论和技术应用并整合到两个具有重大社会意义的概念系统中：分布式基站提供多天线功能，即使在标准天线阵列太大的低载波频率(例如，白色空间频率)。分布式911，使得节点集群能够与可能移动的远距离救援车辆通信，该救援车辆可能在任何一个节点的范围之外。我们的目标是进行足够详细的设计和性能评估，以清除实施的概念障碍。

Over the past two decades, advances in multi-antenna wireless systems have opened up the possibility of tremendous increases in wireless communication throughputs. The practical realization of these increases in real-world wireless networks is constrained by size and cost considerations that limit the number of antennas, especially for mobile devices. This research aims to achieve the gains from multi-antenna techniques in a distributed fashion by having groups of wireless transceivers pool together and cooperatively act like a virtual antenna array. The concept of virtual arrays has broad transformative potential for wireless networks by extending the numerous benefits of multi-antenna systems to networks of single-antenna devices. We will prototype and demonstrate virtual array techniques experimentally on a software-defined radio platform, and we plan to share our implementations as reusable building blocks to stimulate technology transition and to promote interactions between the academic, open-source software community and radio hobbyist communities. The elements of a virtual array have an unknown, typically time-varying, geometry and are driven by independent oscillators, each with stochastic drift; the main technical challenge is in maintaining distributed coherence in the array in the presence of these effects. While this is a very challenging problem, recent results have demonstrated the feasibility of virtual arrays.This research will establish a solid theoretical foundation for distributed coherence and chart a clear path to technology transfer by applying the theory and techniques to the cross-layer design of concept systems based on virtual antenna arrays. Specifically we will develop a state space framework for tracking and prediction of oscillator dynamics and mobility, and scalable architectures for distributed transmission and reception appropriate for large distributed arrays of low-cost single-antenna devices. We will also identify fundamental tradeoffs and scaling laws for virtual arrays. We will apply and integrate the theory and techniques to two concept systems of great societal significance: Distributed base station provides multi-antenna capabilities even for low carrier frequencies where standard antenna arrays would be too bulky (e.g., white space frequencies). Distributed 911, enables a cluster of nodes to communicate with a possibly moving distant rescue vehicle which would be out of range for any one of the nodes. Our goal is to perform design and performance evaluation in sufficient detail to clear conceptual hurdles for implementation.