Reliable Event Detection and Congestion Avoidance in Wireless Sensor Networks

Due to dense deployment and innumerable amount of traffic flow in wireless sensor networks (WSNs), congestion becomes more common phenomenon from simple periodic traffic to unpredictable bursts of messages triggered by external events. Even for simple network topology and periodic traffic, congestion is a likely event due to time varying wireless channel condition and contention caused due to interference by concurrent transmissions. Congestion causes huge packet loss and thus hinders reliable event perception. In this paper, we present a congestion avoidance protocol that includes source count based hierarchical medium access control (HMAC) and weighted round robin forwarding (WRRF). Simulation results show that our proposed schemes avoid packet drop due to buffer overflow and achieves more than 90% delivery ratio even under bursty traffic condition, which is good enough for reliable event detection.