Wireless sensor network is an important technology extended from wireless Ad Hoc network. This new technology can apply on many business and science research. In the past few years, wireless sensor network has some great advance, but it still not good enough and still has much work to do. The most important feature is that every sensor use battery to operate and the battery cannot recharge or replacement. In other word the life of the battery is the life of the sensor or even the sensor network. The import issue about wireless sensor network is "how to save energy". The purpose of this research is to extend the life of wireless sensor networks. In this paper, we proposed a new way to let much more sensors go into sleep mode while maintaining the same sensing area.
