GPSR [6] is a geographic routing protocol proposed for
mobile adhoc networks. It is considered most effective
protocol because of its better packet delivery ratio and low
packet delay. Though this protocol appears to be
comprehensive solution for vehicular adhoc networks it
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suffers from the following drawbacks. Firstly, due to the high
mobility, a node may not receive updated location information
from its neighbor since the neighbor has gone out of range.
Hence, when a node has data to forward, it may make wrong
forwarding decisions that leads to packet loss. Secondly,
whenever a node broadcasts the HELLO message periodically
to its neighbors, there is a probability that HELLO message
may be lost due to congestion or channel impairment. This
will lead to the assumption that the neighbor has failed or gone
out of range. This leads to the improper removal ofa neighbor
from the neighbor list. To tackle these problems we use the
concept of lifetime in GPSR. Lifetime is the amount of time a
node exists in the range of another node. Every node will
maintain a lifetime timer, based on lifetime value. By doing
this, the neighbor list can be efficiently maintained, thus
leading to correct forwarding decisions.