Throughput enhancement of starved TCP flow through concurrent transmission

Unfairness problems are critical to TCP flows in wireless multi-hop ad hoc networks. Unfortunately, the traditional TCP has poor interaction with the IEEE 802.11 MAC protocol. The spatial reuse of the channel can improve the performance of wireless ad hoc network. IEEE 802.11 MAC protocol uses DCF mode with extensions to RTS/ CTS, along with the limitation of at least four hop distance between two simultaneously transmitting nodes because of the control signal range which is slightly larger than twice the transmission range of a node. Due to this limitation along with greedy nature of TCP, starvation problem of TCP flows with longer paths is severe. By using concurrent transmission protocols at the MAC layer, like CTMAC, we can achieve simultaneous transmissions within the interference regions and thus increasing the spatial reuse of the channel. In this paper, we have shown with extensive simulations in NS-2 that scheduling multiple concurrent transmissions along the path links, the starvation problem can be reduced considerably and higher flow throughput is achieved.