Bandwidth-Efficient Multicast Routing for Multihop, Ad-Hoc Wireless Networks

In this paper, we propose and investigate a bandwidth-efficient multicast routing protocol for ad-hoc networks. The proposed protocol achieves low communication overhead, namely, it requires a small number of control packet transmissions for route setup and maintenance. The proposed protocol also achieves high multicast efficiency, namely, it delivers multicast packets to receivers with a small number of transmissions. In order to achieve low communication overhead and high multicast efficiency, t he proposed protocol employs the following mechanisms: (1) on-demand invocation of the route setup and route recovery processes to avoid periodic transmissions of control packets, (2) a new route setup process that allows a newly joining node to find the nearest forwarding node to minimize the number of forwarding nodes, and (3) a route optimization process that detects and removes unnecessary forwarding nodes to eliminate redundant and inefficient routes. Our simulation results show that the proposed protocol achieves high multicast efficiency with low communication overhead compared with other existing multicast routing protocols, especially in the case where the number of receivers in a multicast group is large. A. INTRODUCTION An ad-hoc network is a collection of wireless mobile nodes, which form a temporary network without relying on the existing network infrastructure or centralized administration [1]. In traditional cellular networks, a mobile node is only one hop away from a base station, w hich is connected to a wired backbone. On the contrary, ad-hoc networks form a multi-hop network where all communication is over the wireless channel, hopping over several mobile nodes. Typical applications of ad-hoc networks include outdoor special events (such as conferences, concerts and festivals), as well as communications in regions with no infrastructure, in emergencies and natural disasters, and in military maneuvers. Following are salient features of ad-hoc networks: • The network topology is highly dynamic due to frequent node migration and power outages/failures of mobile nodes. • Multi-hopping over several mobile nodes may be necessary to reach destinations due to the limited transmission power of mobile nodes. as computational power, storage capacity, battery power, etc.) in ad-hoc networks are very limited. These unique features of ad-hoc networks pose several new challenges in the design of routing protocols. For example, since mobile nodes act as routers in ad-hoc networks and they have very limited resources, conventional routing protocols which employ frequent route updates through periodic control packet transmissions may not be suitable for ad-hoc networks [2]. Further, routing …