Unlike wired networks, the information transfer in radio networks is inherently of a broadcast nature, due to the properties of electromagnetic propagation in the radio spectrum. Therefore, each data transmission impinges upon multiple nodes, even if they are not the intended destination. The effects of this interference are felt at the physical layer as well as data link, MAC, and network layers. Cooperative communication strives to turn this liability into an asset by treating interference as an additional source of information. The information transmitted across one wireless link, due to the broadcast nature of radio, is (partially and randomly) available to other nodes beside the intended destination. This additional information, distributed throughout the network, may be exploited in a gainful manner. In other words, cooperative communication exploits the statistical variation of the link signal-to-noise ratios, together with the inherent broadcast nature of radio, to yield a more efficient communication system. This research (1) analyzes the impact of physical layer cooperation on the higher layers and (2) develops methods and algorithms to realize the benefit of cooperation in the data link layer, MAC layer, and the network layer. The impact of this research includes lower node power consumption and thus longer battery life, lower radiated power leading to smaller energy node footprint, higher network throughput, and more flexible allocation of network resources.
