Nomadic control packet-based dynamic route maintenance scheme for adaptive routing in mobile ad hoc networks

Many novel ideas have been proposed for designing multihop routing protocols in MANET (mobile ad hoc networks). Many of them adopt a method, called flooding, to discover a routing path. In order to increase the over-all routing performance and make optimum use of the limited resources, discovered routing paths need to be dynamically maintained to be continuously optimal in the highly dynamic network topology. However, the flooding is inappropriate for the dynamic route maintenance due to its significant inherent overhead. In this paper, we propose a nomadic control packet (NCP)-based dynamic route maintenance scheme for adaptive routing in MANET. The NCP travels through the network based on a random walk, and collects its stopovers as a traversal record for the purpose of dynamic route maintenance and efficient route discovery. The NCP probabilistically provides nodes with clues to routing path updates by using its traversal record. The nodes can find up-to-date and optimal (less-loaded and shorter) routing path information from the clues, thereby adapting to the dynamic network topology and traffic load conditions. The NCP-based dynamic route maintenance scheme can be easily applied to ad hoc on-demand routing protocols such as AODV and DSR with minimum modifications. In our simulation study we modified the AODV protocol to maintain routing paths using NCPs´ traversal record. The simulation results show that the utilization of NCPs helps the routing protocol to notably reduce average end-to-end packet delay with the help of the increased route optimality and traffic congestion control.