Collaborative Research: Distributed Error Correction Strategies in Wireless Networks

基于多跳的网络无线通信正迅速成为未来无线系统的主要架构，包括蜂窝和WiFi网络、网状网和传感器网络的多跳扩展。这些类型的网络的共同之处在于，它们不是完全非结构化(或自组织)的网络，但流量被路由并累积到一个共同的目的地。由于这一特性，这些网络将被称为具有流量积累的网络，或NETA。由于增加的流量负载和干扰，流量积累在公共目的地周围造成了热点或瓶颈。尽管热点问题严重，但缺乏有效的方法来应对。本研究针对NETAS中的热点问题，针对两个重要的子类--线状网络和树状网络，提出了新的分布式纠错策略。在线状网络中，研究人员研究分布式信道编码协议的基本性质和设计，使用串行级联和基于协议图的结构来增强目的地附近的纠错能力，而不牺牲不良带宽效率。在树形网络中，几个源节点可能希望使用公共的中继节点来将它们的信息广播到多个目的节点，这些目的节点可以访问来自“偷听”的源消息的边信息。研究人员探索了一种新的方法，其中每个信源使用一个不同的低速率码来传输到中继器，而解码的消息使用高速率的“嵌套码”进行重新编码。此外，还考虑了层间问题，特别是有效的信道接入和路由方案以及所提出的编码方案的联合设计。

Networked wireless communications over multiple hops is rapidly emerging as the main architecture of future wireles systems, including multihop extensions of cellular and WiFi networks, mesh networks, and sensor networks. Common among these types of networks is that they are not completely unstructured (or ad hoc) networks, but traffic is routed and accumulated towards a common destination. Due to this characteristic property, these networks will be referred to as Networks with Traffic Accumulation, or NETAs. Traffic accumulation creates hot sposts or bottlenecks around the common destination because of the increased traffic load and interference. Despite the severity of the hot spot problem, there is a lack of efficient methods to cope with it. This research addresses the hot spot issue in NETAs by developing new distributed error correction strategies tailored to two important subclasses- line networks and tree networks. In line networks, the investigators study fundamental properties and the design of distributed channel coding protocals using serially concatenated and protograph-based constructions to strengthen the error correction capability near the destination without sacrificing badwidth efficiency. In tree networks, several source nodes may wish to employ a common relay node to broadcast their information to multiple destination nodes which may have access to side information from "overheard" source messages. The investigators explore a novel approach where each source uses a distinctlow rate code for transmission to the relay, whereas the decoded messages are re-encoded using a high rate "nested code". In addition, interlayer issues are considered, in particular the joint design of efficient channel access and routing schemes together with the porposed coding schemes.