Achieving reliability over cluster-based Wireless Sensor Networks using backup cluster heads

Wireless Sensor Networks (WSN) are becoming a viable tool for many monitoring applications. These applications may be of critical nature where the transportation of the information of events from the region of interest to some base station is crucial, where the data loss can not be tolerated. In the cluster-based two-tier WSN, where cluster-head nodes gather data from sensors in their clusters and then transmit to base station, when cluster head nodes start to die, the coverage of those clusters is lost and it leaves the region unmonitored. Even if the cluster heads are rotated and reassigned after some time, until the next rotation that cluster in question will be out of cluster head and will lose coverage. A lot of information is lost which is sensed and sent by the sensor nodes of the cluster to the dead cluster head. We propose here to select backup cluster heads (BCHs), for those cluster heads which are close to deplete their energy. The cluster head, when about to die, sends an SOS with the gathered information until then, to the respective BCH which takes over the responsibility and continues to work as a new cluster head. To evaluate the effect and results of BCH we used LEACH-C protocol and compared the data loss ratio with and without a BCH.