  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.
