On the Performance of Cooperative Routing in Wireless Networks

This paper studies energy and throughput performance of cooperative routing in wireless networks that support cooperative beamforming at the physical layer. Cooperative beamforming is a form of cooperative communication in which multiple nodes each equipped with a single omnidirectional antenna coordinate their transmissions in such a way that the individual signals constructively combine at the intended receiver, resulting in significant power gains compared to independent signal transmissions. It has been recently shown that significant energy savings can be achieved by jointly optimizing the network-layer routing and physical-layer cooperation, i.e., cooperative routing. While energy efficiency of cooperative routing has been extensively studied in literature, its impact on network throughput is surprisingly overlooked. In this paper, we show that while cooperative routing can achieve considerable energy savings, it results in a sharp reduction in network throughput compared to non-cooperative routing. We then identify some potential causes of this problem and propose two solutions by exploring recent developments in multi-beam cooperative beamforming to increase parallelism in the network in order to improve throughput.