Transmission of TCP Traffic over User Cooperative Communications in Infrastructure Networks

This paper studies TCP performance when running over a wireless network that implements cooperative communications. Two well-known cooperative communications schemes were considered: Amplify-and-Forward and Decode-and-Forward. Also, two cross-layer cooperative communications schemes that leverage on the link layer retransmission scheme were considered. These schemes transmit the message from the cooperating node only when necessary. The study in this paper validates guidelines from analysis, with a simulation that implements all layers of the Internet protocol stack. The results show that as the source-destination channel becomes more degraded, both Amplify-and-Forward and Decode-and-Forward cooperation yield a TCP performance better than non-cooperative scheme. This is even considering that the two-phase operation of cooperative communications reduces the effective capacity. The issue of reduced capacity is resolved with cross-layer schemes, which result in improved performance at the cost of added complexity to implement the cross-layer mechanisms and to dynamically schedule the transmission of the cooperating node.