Geographic routing (also called georouting or
position-based routing) is a routing principle that relies on
geographic position information. It is mainly proposed for
wireless adhoc networks and based on the idea that the source
sends a message to the geographic location of the destination
instead of using the network address. In this routing scheme
every node obtains its position information through GPS and
also maintains the knowledge of its one hop neighbors by
exchanging HELLO messages. Nodes determine the position
of the destination through location services schemes proposed
for geographic routing [1]. Geographic routing protocols
typically have a lower delay of packet delivery than reactive
routing protocols [3]. This is because it has no route
acquisition delay such as route request flooding and route
maintenance. In terms of routing overhead, geographic routing
protocols also surpass both reactive and proactive routing
protocols because control packets are only HELLO messages
which are smaller in size, containing sender's ID and sender's
location and are exchanged locally.