Research On Congestion Control Algorithm In Wireless Sensor Networks

WSN(Wireless Sensor Network) is a new network measure and management technology. It is an intelligent network application which can implement data collection, gathering and transmission by itself. WSN closely connect logically information world with genuine physical world, so as to implementing the "compute anywhere" model. WSN has expansive application foreground in national defence and every field of country economic.During the research and experiment of the task, we reference a lot of English and Chinese literatures, studied some current algorithms deeply, In this thesis, we sum up the algorithms and introduce the main method. Based on these characteristics and the limitation of current method, this thesis has done mainly the work of two as follows:(1) This thesis proposes an adaptive scheme to alleviate congestion in sensor networks. Every node has its own neighbors' information table, which includes ID, congestion level and residual energy. It attempts to alleviate the congestion by creating more routing paths. When creating new path is failed, the thesis introduces aggregate fairness model to reduce forwarding rate in proportion to upstream link's aggregate flow weight and to alleviate the congestion. Simulations demonstrate that the scheme can improve energy efficiencies, reduce the number of dropped packets and ensure that some important data packets can reach sink node timely and fairly.(2) According to the characteristic of WSN, we introduce a new definition of fairness and joint entropy into alleviation congestion scheme based on the current fairness. It's called EFRS (Joint Entropy based Fair Rate alleviation Congestion Scheme). EFRS will distribute the bandwidth in proportion to the value of joint entropy, to alleviate the congestion. And the actual rate of upstream nodes will be bounded by the algorithm of token-bucket. Extensive simulations demonstrate the scheme can reduce the number of dropped packets, improve energy efficiency and make sure that the number of received data packets is in proportion to the number of useful data which are contained in the data packets.Finally, this paper summarizes all the works and views the future work.