Congestion in Wireless Sensor Networks and Various Techniques for Mitigating Congestion - A Review

In wireless sensor networks (WSNs), congestion occurs, for example, when nodes are densely distributed, and/or the application produces high flow rate near the sink due to the convergent nature of upstream traffic. Congestion may cause packet loss, which in turn lowers throughput and wastes energy. Therefore congestion in WSNs needs to be controlled for high energy-efficiency, to prolong system lifetime, improve fairness, and improve quality of service (QoS) in terms of throughput (or link utilization) and packet loss ratio along with the packet delay. In this paper the characteristics of WSNs are reviewed and challenges of reliable data transport over WSNs are discussed. The proposed reliable congestion control protocols and data transport protocols for WSNs are reviewed and summarized. The recent research progress in developing suitable transport protocols for WSNs, are surveyed. And finally, some future research directions of transport protocol in WSNs are discussed.