Wireless sensor networks offer easy implementation, flexibility and mobility of hand held

devices. Sensors consist of an internal power source, which is the great limitation for

the life time and the usage of sensor networks. To increase the life time, sensors should

stay in energy saving sleep mode as long as possible, because in sleep mode the radio is

either shut down or working with less energy. Better energy handling is implemented in

different power saving mechanism of common Medium Access Control protocols, which are

evaluated and analyzed and further extensions and ideas to improve the energy efficiency

are presented. Slotted PSM is simulated with the NS2 and compared to the WLAN 802.11

PSM technology and the results show that energy efficiency and power consumption are

much better implemented and life time increases with the use of Slotted PSM.