Routing and multicasting strategies in wireless mobile ad hoc networks

Ad hoc networks are gaining increasing popularity in recent years because of their ease of deployment. No wired base station or infrastructure is supported, and each host communicasts one another via packet radios. In ad hoc networks, routing protocols are challenged with establishing and maintaining multihop routes in the face of mobility, bandwidth limitation and power constraints. In this dissertation, we study the routing strategies for ad hoc networks. On-demand routing protocols and table-driven algorithms are analyzed and compared against each other. Our study shows that on-demand protocols are better suited for mobile networks because they generate less control overhead and manage the mobility in a more efficient manner. Simulation experiments also indicate that providing multiple routes is beneficial in increasing the robustness against mobility.; We investigate the scalability characteristics of on-demand routing protocols and propose schemes to enhance the performance. We also study the interaction between MAC (Medium Access Control) and routing protocols by simulation.; Based on the lessons learned from the performance evaluation studies, we design new on-demand protocols. We introduce three unicast routing algorithms with different approaches. AODV-BR (Ad hoc On-demand Distance Vector with Backup Routes) is a scheme applied to the existing AODV protocol for establishing backup routes while the primary route is constructed, without transmitting additional control messages. Backup routes are utilized when the primary path is disconnected. The Split Multipath Routing (SMR) protocol builds maximally disjoint routes. Providing multiple routes helps minimizing route recovery process and reducing control overhead. Distributing traffic into multipaths prevents nodes from being congested. Dynamic Load Aware Routing (DLAR) is a protocol that uses the load of the intermediate nodes instead of the shortest distance, as the main route selection metric. The protocol attempts to avoid building routes with congested links.; We then present the On-Demand Multicast Routing Protocol (ODMRP), a novel multicasting scheme that utilizes a mesh structure. Multiple routes created by the mesh make the protocol robust to mobility. Multicast routes and group membership are obtained on demand to use the network resources efficiently and effectively. Simulation study shows that ODMRP outperforms other popular multicast protocols.