Optimal routing of multicast traffic in ad hoc networks

Abstract

In recent years wireless communication has become very popular in the telecommunication industry. More and more users can reach portable devices, which are capable to form a great wireless network. The existing network protocols used in wired networks do not support in an efficient way the new features added by these wireless systems. Moreover they limit the mobility of the nodes or introduce unnecessary overhead. Two types of wireless mobile networks exist: Networks with infrastructure (like Mobile IP or Cellular Networks), and networks without infrastructure or ad hoc networks. The last ones are constituted by an assembly of wireless mobile nodes that move randomly and can be connected dynamically and arbitrarily among themselves. Due to the characteristics of the physical medium and the used signal power, these nodes must function like local routers, which discover and maintain routes to other nodes of the ad hoc network. Moreover, the routing protocols must adapt fast and dynamically to the topology changes taking into account parameters like the bandwidth, or energy consumption. The first part of this work consists of a technology review of ad hoc networks, where the most common protocols used in ad hoc networks are described, specially those ones which are related to our research problem: multicast with energy conserving. The goal of our work is to find an algorithm which keeps the system working as long as possible and at the same time reaches several destinations with the same information by using multicast techniques. An earlier study using unicast traffic developed an optimal protocol named Flow Augmentation. The protocol prolongs the system lifetime by doing an optimal distribution of the data flow. In our study, the Flow Augmentation protocol is adapted for multicast traffic. In order to make that adaptation we had to develop a new multicast routing algorithm, called Incremental Tree Algorithm (ITA). This new algorithm will deal with the multicast traffic and the wireless features of the ad hoc networks. Once the multicast algorithm was implemented some network scenarios were simulated in order to get an idea of the performance of the new algorithm.