Impact of channel errors in proactive routing protocols

In proactive routing protocols (such as OLSR) nodes flood their neighborhood information to the entire network. Every node then constructs a topology map which represents its view of the network. This map is taken as a basis to compute the ¿best¿ path to the destination. Inaccurate topology information may result in one of the following: a) packets may be sent in a path that no longer exists; b) routing loops may be formed when two neighboring nodes have a different view of the network; c) packets may be sent through a longer path. In the latter, packets are still being delivered to the destination, thus inaccurate topology information does not necessarily result in packet delivery failures but in this case in increased stretch. In wireless Mobile Ad Hoc Networks, channel errors originated by poor channel quality or mobility can cause the loss of topology control packets. This may consequently result in nodes having an erroneous and/or inconsistent view of the network topology. In this paper, we first describe the Component Based Routing (CBR) approach to routing protocol design and then focus on the evaluation of the topology dissemination component. We analyze the impact that channel errors and node mobility have on the successful delivery of topology control packets and routing protocol performance. We derive models that allow us evaluate performance for different network sizes and node densities. We evaluate the tradeoffs between accuracy of topology information at any given time, power consumption and overhead for both optimized flooding mechanisms (such as those that are used in OLSR) and non-optimized flooding mechanisms (e.g. flat flooding).