Improve preemptive routing performance in mobile ad hoc networks with Cache-enabled method

In the reactive routing algorithms of mobile ad hoc networks (MANET), preemptive routing method tries to warn the source node and to tell it to change route in time before a link is about to break. This method alleviates the problem from packet losses, and shortens the delay of route change after a route failure. However, it also decreases the number of route error packets which play an important role in removing stale route entries from node cache, i.e. it disables the cache function. In this paper, we propose a protocol called Cache-enabled Preemptive Dynamic Source Routing (CPDSR), and try to reserve the cache function in preemptive routing method. Simultaneously, we give a definition of Reaction Time which determines exactly when a link is regarded as unstable and is a key ingredient in preemptive routing method. Our definition is in accordance with our method and proves to be more reasonable. The simulation result shows that our work can improve the performance of preemptive routing greatly in overhead and end-to-end delay.