Performance of multipath routing for on-demand protocols in mobile ad hoc networks

Mobile ad hoc networks are characterized by multi-hop wireless links, absen ce of any cellular infrastructure, and frequent host mobility. Design of ef ficient routing protocols in such networks is a challenging issue. A class of routing protocols called on-demand protocols has recently found attentio n because of their low routing overhead. The on-demand protocols depend on query floods to discover routes whenever a new route is needed. Such floods take up a substantial portion of network bandwidth. We focus on a particul ar on-demand protocol, called Dynamic Source Routing, and show how intellig ent use of multipath techniques can reduce the frequency of query floods. W e develop an analytic modeling framework to determine the relative frequenc y of query floods for various techniques. Our modeling effort shows that wh ile multipath routing is significantly better than single path routing, the performance advantage is small beyond a few paths and for long path length s. It also shows that providing all intermediate nodes in the primary (shor test) route with alternative paths has a significantly better performance t han providing only the source with alternate paths. We perform some simulat ion experiments which validate these findings.