Sink-Initiated Geographic Multicasting Protocol in Wireless Sensor Networks

There have been many geographic multicasting protocols proposed for wireless sensor networks (WSNs). These protocols tend to exploit a SOurce-initiated Geographic Multicasting (SOGM) approach which consists of three phases: first, a source collects the position information of all sink nodes; second, the source constructs a multicast tree through the position information; third, the source forwards data down the multicast tree. However, if a multicast group contains many mobile sinks, frequent movement of the sinks cause a huge number of link failures of the multicast tree. To fix them, the SOGM approach requires a great deal of delivery of position registration and update messages to the source, thus leads to significant energy consumption of the sensor nodes in the vicinity of the source. Moreover, since each sink asynchronously updates one´s new position to the source, it is difficult for the source node to find an opportune time for reconstructing the multicast tree. In this paper, we propose a SInk-initiated Geographic Multicasting (SIGM) protocol for WSNs which can avoid these problems faced by the SOGM approach. The SIGM allows sinks to construct their own data delivery paths to a source, and a multicast tree is automatically constructed by merging the data delivery paths. Simulation results show that the proposed protocol is superior to other protocols in term of average energy consumption, it thus prolongs the network lifetime.