Congestion control for streaming service in IEEE 802.11 multihop networks

The existing congestion control algorithms for streaming service experience the performance degradation over IEEE 802.11 multihop network because they mainly focus on the prevention of the buffer over flow at the specific node. However, congestion collapse happens not because of the buffer over flow but because of the serious contention at multiple nodes. As the MAC layer contention becomes serious, the end-to-end delay and the packet loss rate due to collision increase while throughput smoothness is not guaranteed due to fluctuation of the queueing delay at each node. Here, the authors propose a TCP-friendly congestion control algorithm based on the MAC layer contention state to improve streaming service. Specifically, each flow controls its transmission rate based on the estimated contention state which each node notifies to each flow by marking packets. The simulation results show that the proposed algorithm utilises the channel bandwidth more efficiently with providing throughput smoothness compared with the existing algorithms.