Scalable broadcast strategies for ad hoc routing protocols

In ad hoc wireless networks, routes are discovered either by means of a periodic update between 1-hop neighbors or by using a reactive routing protocol which relies on an explicit route discovery process. Although the major advantage of a reactive protocol is the reduction in the routing overhead, the conventional flooding mechanism used to propagate the route request (RREQ) message during the route discovery process does not scale well to large networks. In addition to the overhead problem, the way in which the route request gets propagated across the network affects the network performance in two different ways: (i) it determines how fast the route can be acquired; (ii) it is also an important factor in determining the availability and quality of the route. In this paper, we propose three novel RREQ broadcast techniques, i.e., weighted p-persistence, slotted p-persistence, and slotted p-persistence schemes. Our simulation results show that the proposed schemes can achieve up to 75% routing overhead reduction while keeping the route acquisition delay close or equal to the conventional flooding scheme.