Abstract: According to the packet loss problem in S-MAC protocol, this paper proposed an optimized scheme which based on the cache queue principle and simplified the format of group data for S-MAC protocol. Combined with the Acfive Message(AM) mechanism of TinyOS, the S-MAC protocol has been implemented on the Mica2 motes, and it has tested the packet loss ratio of MAC layer. hhe result demonstrates that the improved S-MAC protocol has significantly reduced than the original S-MAC protocol in the packet loss ratio and enhances the network throughput.

Key words: WSN,S-MAC protocol,Packct loss radio,Cachc qucuc,tinyOS