SOM: spiral-fat-tree-based on-demand multicast protocol in a wireless ad-hoc network

A mobile ad-hoc network (MANET) is characterized by multihop wireless links, in the absence of any cellular infrastructure, as well as by frequent host mobility. Existing on-demand multicasting protocols are classified into tree-based and mesh-based schemes. This paper presents a robust multicast routing protocol, called the Spiral-fat-tree-based On-demand Multicast (SOM) protocol, which is a means of dynamically establishing a special tree data structure, namely the spiral-fat-tree, in the MANET. The spiral-fat-tree is constructed by appending some backup paths to a multicast tree constructed by our scheme for the purpose of improving the robustness of the multicast tree. The contribution of the spiral-fat-tree is to maintain the stability and increase the robustness of the multicast tree. A performance study shows that our proposed scheme outperforms existing on-demand multicast protocols. (C) 2002 Elsevier Science B.V. All rights reserved.