Reducing the energy consumption by wireless communication devices is perhaps the most important issue in the widely-deployed and exponentially-growing IEEE 802.11 Wireless LANs. In the IEEE 802.11 power saving mode specified for DCF, time is divided into so-called Beacon Intervals. At the start of each Beacon Interval, each node in the power saving mode periodically wakes up for a duration called the ATIM Window. The nodes are required to be synchronized to ensure that all nodes wake up at the same time. During the ATIM window, the nodes exchange control packets to determine whether they need to stay awake for the rest of the Beacon Interval. In this thesis, we describe a series of experiments which obtained detailed measurements of the energy consumption of IEEE 802.11 wireless network interface operating in an ad-hoc networking environment. Energy Consumption Model of IEEE 802.11 wireless network interface operating in ad-hoc networking environment is designed based on experiments. Furthermore, we propose more energy efficient IEEE 802.11 PSM mechanism in standby state and Synchronized Hello message in AODV routing protocol.