Routing protocols for Mobile Ad Hoc Networks (MANETs) have been extensively studied for more than fifteen years. Position-based routing protocols route packets towards the destination using greedy forwarding (i.e., an intermediate node forwards packets to a neighbor that is closer to the destination than itself). Different position-based protocols use different strategies to pick the neighbor to forward the packet. If a node has no neighbor that is closer to the destination than itself, greedy forwarding fails. In this case, we say there is void (no neighboring nodes) in the direction of the destination. Different position-based routing protocols use different methods for dealing with voids. In this paper, we use a simple backtracking technique to deal with voids and design a position-based routing protocol called "Greedy Routing Protocol with Backtracking (GRB)". We compare the performance of our protocol with the well known Greedy Perimeter Stateless Routing (GPSR) routing and the Ad-Hoc On-demand Distance Vector (AODV) routing protocol as well as the Dynamic Source Routing (DSR) protocol. Our protocol needs much less routing-control packets than those needed by DSR, AODV, and GPSR. Simulation results also show that our protocol has a higher packet-delivery ratio, lower end-to-end delay, and less hop count on average than AODV.
Lin and Kus proposed LGR @cite_1 which is a location-fault-tolerant geographic routing protocol that uses both traditional geographic routing and position-based clustering technique. Routing is performed using global geographic routing and local gradient routing. A cluster head (CH) broadcasts messages to all the nodes in its own cluster as well as all nodes in its neighboring clusters so that each of these nodes can establish a routing path to the CH. This process affects scalability. If nodes are highly mobile, frequent CH election occurs which results in more message broadcasting by newly elected CHs to announce their existence which overwhelms nodes with control packets exchanged between nodes and hence limits scalability.
@cite_1
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Geographic routing protocols for wireless ad hoc networks have gained great attention in the anticipation of the broader use of GPS or other localization schemes. However, location inaccuracies depending on environment and the localization system may affect the performance and even correctness of geographic routing. In this paper, we propose a novel Location-fault-tolerant Geographic Routing (LGR) scheme based on the combination of position-based clustering and geographic routing technologies. We divide the routing problem into the global geographic routing step and the local gradient routing step. Performance analyses and the NS-2 simulation results demonstrate that our scheme has much better performance than others when facing location inaccuracies.