No abstract

The wireless networks have become an integral component of the modern communication system. The mobile terminals have limited battery life. Also ad-hoc networks are used in situations like disaster management, battlefield etc. where the resources available for battery recharge would be limited. Hence energy efficiency is an important design criterion for ad-hoc networks. IEEE 802.11 provides a mechanism known as PSM (Power saving mechanism) in MAC layer which reduces the power consumption by the transition of mobile stations between awake and doze state. Here the energy efficiency is high when the network load is small but decreases with the increase in network load. For RTS-CTS scheme, the energy efficiency is high when the network load is heavy. Hybrid Drive Scheme (HDS) combines RTS-CTS scheme with the conventional PSM so that energy efficiency is high even if the network load is light or heavy. But after each data transmission, beacon frames are transmitted which cause additional energy wastage. This paper presents a novel energy saving mechanism, called as Enhanced Hybrid Drive Scheme (E-HDS), which extract the features of PSM as well as RTS-CTS scheme. Here a single beacon frame is transmitted per beacon interval which reduces energy wastage. Hence E-HDS out-performs HDS. Also E-HDS could obtain high energy efficiency than conventional scheme in the IEEE 802.11 standard irrespective of the network load conditions.