Aiming at routing hole problem existing in the traditional geographic routing

a novel label-based greedy forwarding（LBGF） algorithm is proposed.This algorithm organizes nodes in the network as a ringed tree. While building the tree

a label implying relative relationships between nodes is assigned by the parent node for the child node

depending on its location

thereby a tree-label system is formed

and based on the system

the corresponding greedy forwarding algorithm is designed.Analysis and simulation results show that LBGF has many advantages such as hole-avoidance

stronger fault-tolerance

lower communication and storage cost

simple computation

and so on

compared with GPSR.So it is suitable for WSNs whose nodes are sparse

or in which there are many obstacles.