Ad Hoc Networks An Improved Energy-saving Mac Protocol

The traditional wireless networks with centralized network topology (such as cellular systems and WLAN with AP) have been challenged to certain extent by the novel ad hoc network topology (such as Ad Hoc networks, wireless sensor networks, and wireless mesh networks). The centralized network topology is characterized by the advantage of its large coverage, centralized network management and unlimited energy supply (from fixed power supply), which can be taken advantage for long-range wireless communications. On the other hand, the ad hoc network has the advantage of flexible topology, requiring no infrastructure, and easy deployment temporarily, and it has attracted much attention and intensive research, especially in some special middle- or short-range application scenarios, such as disaster relief efforts, exhibition, and battlefield.Since the mobile node in Ad Hoc networks was powered by limited battery instead of fixed power, special attention should be paid to the power consuming while designing protocols for Ad Hoc network. So, in this paper we propose a power efficient MAC layer protocol. This new protocol - PAMAS-P, makes several improvements to the famous PAMAS protocol, which is designed for Ad Hoc network to save power. Data Sending packets and Probe packets are added to confirm the hibernation time and reduce collision; data channel will be kept shutting down while the node is competing channel (that means the node is not sending or receiving data); controlling channel will be closed and opened periodically. All these means are designed to reduce the power consuming to improve the protocol performance in term of power saving. Finally, we run our PAMAS-P protocol in NS-2 and the results show the new protocol works very well.