Geographic routing is widely used in wireless sensor networks due to its great efficiency

low routing overhead and good scalability.However

the problem that most of the geographic routing algorithms which adopt greedy algorithm as their basic routing strategies have to face is the 'routing void phenomena’.Aiming at this problem

this paper presents a new geographic routing algorithm

Greedy algorithm based on the geographic information of 2-hop neighbors (Greedy-2).Greedy-2 algorithm makes nodes be aware of the existence of voids before the packet reaches a region where the Greedy forwarding fails

so that the packet can bypass the dead-end node ahead of time to reduce the probability of encountering the routing voids.PATN

a Planarization Algorithm based on Two-hop Neighbors

is also introduced.PATN ensures the success of perimeter routing through the planarization without extra overhead

and guarantees delivery in UDG networks when Greedy-2 algorithm fails.Extensive simulation further shows that Greedy-2 algorithm can significantly decrease the routing void phenomena.It obtains better performance than Greedy algorithm based on 1-hop neighbors in aspects of the packet delivery rate and the length of routing path.GPSR-2

which combines Greedy-2 and PATN algorithms

has less average length of routing path than GPSR.