Performance Study of Node Placement for Congestion Control in Wireless Sensor Networks

Performance of wireless sensor networks (WSNs) can be affected when the network is deployed under different topologies. In this paper we present a performance study of congestion control algorithms in WSNs when nodes are deployed under different topologies. To perform our research we have employed algorithms SenTCP, directed diffusion, and HTAP. The choice of these algorithms is based on the fact that they cover two major methods used for congestion mitigation. These are: a) decreasing the load by source rate reduction (used in SenTCP) and b) increasing resources as these would help in emptying the buffers of intermediate sensor node though the creation of alternative paths (used in HTAP) or creation of multiple paths used in directed diffusion). We have examined the performance of these algorithms with respect to their ability to maintain low delays, to support the required data rates and to minimize packet losses under four different topologies. The topologies we have used are simple diffusion, constant placement, R-random placement and Grid placement. Results indicate that congestion control performance in sensor networks can significantly be improved, in algorithms that use multiple or alternative paths to forward their data in case of congestion (directed diffusion and HTAP). Performance of rate-controlled algorithms like SenTCP exhibit improvement in terms of packet latency.