MAC layer intelligent split-stream scheme for alleviating congestion in Ad hoc networks

Ad hoc networks, which are multi-hop and autonomous decentralized networks, have broad perspective in military communication, emergency communication, sensor networks and so on. Enhancing the performance of Ad hoc networks is one of the important objectives in the design of networks while congestion is a significant contributor that leads to network performance degradation. Many different congestion control strategies in transport layer, network layer, MAC layer and even cross-layer have been widely researched. Jian Liu et al. bring forward ATCP to improve traditional TCP congestion control in ad hoc networks (Liu and Signh, 2001). Reference (Shit et al., 2009) proposes a MAC layer congestion control mechanism which mainly uses the congestion window to control the MAC´s sending rate in 802.11 WLANs. D. Kliazovich and F. Granelli(Dzmitry and Fabrizio, 2006) research a crosslayer congestion control scheme, in which transport layer´s data stream is adjust by the information of link layer, such as bandwidth and delay. The essential reason causing congestion is that user data rate exceeds link data transmit rate capability. Most of the congestion control strategies research how to control user data rate properly to achieve the goal. However, in this paper we investigate MAC layer intelligent split-stream scheme to improve data transmit rate capability for alleviating congestion in Ad hoc networks. In a practical Ad hoc network, due to terrain and interference, link qualities of the paths to some nodes are quite good while those to others are relatively bad. Single node conventionally selects good path expecting great performance of itself. However, multi-nodes all select good path often cause severe competition at MAC, which eventually lead to performance degradation of the whole network.