Improving the efficiency and reliability of the route discovery process in on-demand routing protocols

Three-hop horizon pruning (THP) is an algorithm for computing a two-hop connected dominating set (TCDS) of the network, and has been shown to be more efficient than all prior distributed broadcasting mechanisms when a TCDS is preferred over a connected dominating set (CDS). However, like all other algorithms that depend on local topology information, THP is not reliable when the topology changes frequently. We describe and analyze the three-hop horizon enhanced pruning (THEP), which eliminates THP's limitations. First THEP adopts a virtual radio range (VR) that is shorter than the physical radio range (RR), and considers as one-hop neighbors only those nodes within VR. The gap between VR and RR works as a buffer zone in which nodes can move without loss of connectivity. Second, upon receiving a broadcast packet, the forwarder list in the packet header is analyzed together with the current information about the local neighborhood. Based on this, a node using THEP may decide to broadcast a packet even though it has not been selected as a forwarder by the sender. We conduct extensive simulations and show that AODV-THEP attains better performance than AODV in terms of delivery ratio, control overhead, packet collisions, and end-to-end delay.