Destination-Initiated Geographic Multicasting Protocol in Wireless Ad Hoc Sensor Networks

There have been proposed many geographic multicasting protocols for wireless ad hoc sensor networks. Most of these protocols tend to exploit a Source-initiated Geographic Multicasting (SGM) approach which consists of three phases: first, a source collects the position information of all destination 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 destinations, the SGM approach may cause a great deal of delivery of position registration and update messages to the source, thus lead to significant energy consumption of the sensor nodes in the vicinity of the source. In addition, high data delivery latency is another problem since the data delivery is triggered after the source obtains the position of all destinations and constructs a geographic multicast tree. Moreover, since each destination asynchronously updates one´s new position to the source, the source node in the SGM approach is difficult to find an opportune time for reconstructing the multicast tree. In this paper, we propose a Destination-initiated Geographic Multicasting (DGM) protocol which can avoid these problems faced by the SGM approach. The DGM allows destinations to construct their own data delivery paths to a source, and a multicast tree is automatically constructed by merging the data delivery paths, and then, the source node forwards data to them down the multicast tree. In the DGM, we also propose a round-based virtual infrastructure with a radial shape for increasing the merging probability of data delivery paths and reducing reconstruction ratio of the multicast tree due to mobility. Simulation results show that the proposed protocol is superior to other protocols in term of average data delay and average energy consumption.