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Due to the limited energy of sensor nodes, it is a research goal that the lifetime of sensor networks is prolonged by transmitting the sensed data to the base station in an energy-saving way. Previous algorithms aim at reducing the average energy consumption rate to extend the network lifetime. However, some nodes sometimes may be served as the cluster-head too many times to conserve their energy, resulting in reduced network lifetime. Thus, the large deviation of network lifetime makes these algorithms impractical. This paper proposes a new clustering algorithm which not only reduces the average energy consumption rate, but also converges the residual energies of all nodes on a small interval. Based on the two-region cluster-heads selection mechanism, the coordinator adaptively adjusts the far-near regions to converge the energies of all nodes on a small interval. With the exclusion-circle of clusterheads, cluster-heads can be distributed evenly in a spatial respect for each round, resulting in reduced energy consumption. The simulation results show that the proposed algorithm not only makes cluster-heads distribute evenly in a spatial respect but also converges the residual energies of all nodes on a small interval, resulting in extending the network lifetime significantly and stably.

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Geocasting, a variant of conventional multicasting, uses the location technology to deliver messages. However, recent geocast protocols extensively use flooding and broadcasting approaches. When network load is heavy, the chance of collision will be increased and then packets will probably be damaged or lost. The purpose of this paper is to propose an Adaptive HandshakingBased Geocasting protocol (AHBG). In this protocol, we employ handshaking-based forwarding for data transmission instead of flooding. Simulation results show that AHBG achieves high delivery ratio (nearly 100%) with low overhead (at least 21% reduction compared with other protocols).

No abstract