Mobile data collector strategy for delay-sensitive applications over wireless sensor networks

Applications that require fast response time such as emergency preparedness and hostile environment surveillance pose challenging obstacles to wireless sensor network (WSN) protocols. A routing protocol must provide fast and reliable techniques for data propagation. Most routing solutions for WSNs utilize static sinks to collect data from the entire network. This approach results in high traffic load in the sink's vicinity. The nodes located near the sink will be more requested than other nodes in the network. Therefore, these nodes will consume more energy and face high congestion in a large scale network. In this paper, we propose a solution to the problem of deploying mobile data collectors in order to alleviate the high traffic load and resulting bottleneck in a sink's vicinity caused by static approaches. Our proposed MDC/PEQ protocol employs mobile data collectors (MDCs) that broadcast beacons periodically. Sensor nodes that receive the beacon will join the MDC's cluster and update their routing information in order relay data packets to the MDC. Sensor nodes use the signal strength of the beacon in order to perform a simple but efficient route re-configuration (handoff). An extensive set of simulation experiments is conducted and results confirm that the introduction of mobile data collectors in wireless sensor networks reduces the bottleneck at the nodes closer to the sink. Our proposed mobility technique for data gathering introduces no traffic or energy overhead. In fact, it significantly reduces traffic and, consequently, packet delay and energy dissipation by reducing the average number of hops that data packets traverse from source sensor nodes to sinks or mobile data collectors.