Contention-based congestion control in wireless ad hoc networks

The performance of traditional TCP congestion control protocol degrades when congestion and contention increase in ad hoc networks that use the IEEE 802.11 DCF. Many of the problems result from medium contention at the media access control (MAC) layer. In this paper, we present a new contention-based congestion control (CBCC) method according to a novel congestion information from MAC layer. This proposal aims to avoid the congestion nodes and guarantee better performance in terms of delay, packet delivery ratio, and throughput. By monitoring the number of one node entry the backoff algorithm, our CBCC scheme can calculate the congestion metric called backoff state ratio, a more accurate metric to characterize the network congestion status. Node uses this indication to determine whether to drop a packet or not. Simulation results show that the algorithm can greatly increase the network throughput and effectively control the network congestion at the MAC layer.