Cross-Layer Optimization of OLSR with a Clustered MAC

OLSR, a proactive ad-hoc routing protocol, routes packets without considering the specific characteristics of the underlying MAC in the absence of cross-layer optimization. For a simple clustering MAC where nodes are differentiated according to their roles, MAC ignorant OLSR routing cannot fully optimize the performance of the network. In this paper, some cross-layer optimization options were investigated and the following improvements were achieved: 1) loss optimized routing where packets are routed via paths experiencing the best packet success ratio as measured by the MAC; 2) delay optimized routing where latency sensitive packets are routed via paths that have minimal number of relay nodes; 3) significant OLSR control overhead reduction via hello emission interval adaptation in response to MAC signaled link status; and 4) MAC slot size aware packing of OLSR control messages to maximize slot utilization. In general, these options may be applied to cross-layer optimizing OLSR with other types of MAC so long as the relevant information can be supplied by the MAC.