Hierarchical Tree Alternative Path (HTAP) algorithm for congestion control in wireless sensor networks

Recent advances in wireless sensor networks (WSNs) have lead to applications with increased traffic demands. Research is evolving from applications where performance is not considered as a crucial factor, to applications where performance is a critical factor. There are many cases in the fields of automation, health monitoring, and disaster response that demand wireless sensor networks where performance assurances are vital, especially for parameters like power, delay, and reliability. Due to the nature of these networks the higher amount of traffic is observed when the monitored event takes place. Exactly at this instance, there is a higher probability of congestion appearance in the network. Congestion in WSNs is tackled by the employment of two methods: either by reducing the load (''traffic control''), or by increasing the resources (''resource control''). In this paper we present the Hierarchical Tree Alternative Path (HTAP) algorithm, a ''resource control'' algorithm that attempts, through simple steps and minor computations, to mitigate congestion in wireless sensor networks by creating dynamic alternative paths to the sink. HTAP is evaluated in several scenarios in comparison with another ''resource control'' algorithm (TARA), as well as with a ''traffic control'' algorithm (SenTCP), and also the case where no congestion control exists in the network (''no CC''). Results show that HTAP is a simple and efficient algorithm capable of dealing successfully with congestion in WSNs, while preserving the performance characteristics of the network.