Lifetime Enhancement in Wireless Sensor Networks through Selective Data Handover

Wireless sensor nodes, being highly energy constrained, must function in an energy-efficient manner in order to enhance network lifetime. Thus suitable protocols must be defined in order to minimize the energy dissipated by the individual nodes in the network. The LEACH and PEGASIS protocols are elegant solutions to the problem. While the LEACH protocol randomizes cluster heads for equal energy dissemination, the PEGASIS protocol forms a chain of cluster heads taking rounds in transmitting to the base station. The binary hierarchical model also addresses this issue. In this paper we propose Data Handover Scheme (DHS) which enhances the performance of LEACH, PEGASIS and binary model in terms of network lifetime. The base station being located at variable distances from the individual nodes, in spite of randomization and chain formation, each node actually dissipates a different amount of energy during its turn of transmission to the base station. This energy difference increases quadratically as the base station is located further off from the sensed area and linearly with the number of cycles elapsed and the packet length. DHS eliminates this energy difference by data handover in specific cycles through suitable node pairing and partner swapping. Extensive simulations show that LEACH with DHS performs 16.66% better than LEACH alone, PEGASIS with DHS shows 12.93% improvement over PEGASIS alone and binary model with DHS performs 15% better than the binary model alone considering lifetime for an illustrative small scale network. A generalized mean transfer scheme is devised for large scale networks with significant (3 - 12%) lifetime increment. Furthermore PEGASIS with DHS shows that it attains almost a near optimal solution for the number of cycles endured by the network. As far as our knowledge goes, we are the first ones to address the problem of variable node distances from the Base Station and present a scheme which outperforms all existing schemes in terms of network lifetime.