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.
