| Summary: | 碩士 === 國立清華大學 === 資訊工程學系 === 94 === In this thesis, we consider the problem of group multicast in wireless sensor networks. In group multicast, group members need to multicast messages to all other nodes in the group. The group members may scatter around in the sensor network and require other nodes to relay the message. A common practice is to build an overlay, such as a mesh or a tree, among the group members and then disseminate the messages following the overlay structure. In this thesis, we argue that the overlay multicast must be matched by the underlay routing. We propose to use stateless source routing as the underlay routing scheme instead of straightforward unicast. Stateless source routing encodes the destinations and forwarders into packet header. In this way, a node only needs to transmit the packet once and multiple neighboring nodes that are designated in the header know they should forward the packet and where to forward. On the other hand, using unicast as the underlay, a node needs to transmit the packet once for each destination, consuming more energy in the nodes. In the proposed Aggregation Overlay Multicast (AOM) protocol, we build our overlay multicast on top of stateless source routing schemes like Differential Destination Multicast (DDM). Since wireless sensor nodes are often stationary, it is reasonable to distribute some membership control to group members instead of centralizing at the source node as in DDM. Through simulation we compare our protocol with stateless DDM and the results show that our protocol can achieve better energy efficiency and balance.
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