Abstract: Clock synchronization, one of the key technologies in ad hoc networks, is the base of the implementation of some network functions. This survey gave an overview of popular clock synchronization methods of ad hoc networks.These methods were classified by some different principles. Then the scalability of approaches above was compared and analyzed, so did the network overhead and synchronization error. Because of the similarity of clock synchronization methods between wireless sensor networks(WSN) and ad hoc networks,some clock synchronization methods of WSN were proposed to be used for ad hoc networks. At last, some developments were introduced, which offer great potential for the new coming problems of clock synchronization.

Key words: Cock synchronization, Ad hoc networks, Survey, Master-slave synchronization, Mutual synchronization