Research On The Congestion Control For Wireless Sensor Networks

Wireless sensor networks(WSNs) in the energy, buffer size and capability of computing is limited. The special many-to-one communication mode makes WSNs more prone to network congestion. In WSNs, the congestion not only leads to buffer overflowing, but also increases the transmission time of packets. The existing congestion control methods mainly based on simple congestion feedback and rate adjustment mechanisms, although these methods could mitigate congestion to some extent, but also further increases the transmission time of packets. This paper focuses on WSNs congestion control of key technologies in-depth study. After the congestion of WSNs issues are discussed in detail, and proposed a new algorithm, research contents and innovations are as follows:(1) The reasons of WSNs network congestion are analyzed in detail. A detailed description of congestion detection, notification and controlling and the current research status as well as challenges to be faced.(2) For most of the congestion control method ignores the delay of data transmission problem among nodes, and DACC algorithm was presented. In order to improve non-real and imaginary phenomenon of the existing congestion detection model is based on the buffer occupancy of a single node, DACC presents a new model considering both the real-time buffer occupancy and the average transmission time of packets. At the same time, DACC uses the untapped bits in the IEEE 802.11 DCF frames header to carry congestion information. During the congestion alleviation period, DACC presents a channel occupancy mechanism which is based on the real-time buffer occupancy for the purpose of decreasing delay and preventing packet loss. Simulation results indicate that in terms of delay, packet delivery ratio, collision and buffer load has comparative advantages than others.(3) RACC presents a rate adjustment mechanism for many-to-one communication mode in WSNs. First, the node to estimate the change rate of buffer within the next time based on the received rate and the send rate; and then, RACC presents a local rate adjustment mechanism which is based on the change rate of buffer occupancy. Simulation results show that indicate that in terms of throughput, packet delivery ratio and delay have achieved good results.