Energy Efficient Fundamental Theory and Technical Approach

Abstract

With the goal of mitigating the environmental impact of information and communication technology (ICT) industry, “green” wireless communication technologies have drawn increasing attention from governments, academia and industry. Hence, energy management technique becomes one of the key considerations in the design of future wireless networks, especially for the inherently energy-constrained wireless ad-hoc networks (WANs) discussed in this chapter. Many schemes, which can be adopted at different layers of the protocol stack in order to accommodate the energy awareness in WANs, have been proposed in the recent past. However, it’s absolutely impossible to expect the unilateral reduction of energy consumption as the only goal for the WANs since the diversiform energy-driven performance indicators have to be guaranteed for system’s normal operation. Hence, recent research works focus on providing energy-efficient solutions with regarding to the QoS guarantee. In this chapter, we firstly carry out a comprehensive analysis of the relevant efficiency metrics as the fundamental evaluation, including the spectrum efficiency in b/s/Hz, energy efficiency in b/s/Hz/W (or b/Joule/Hz), area spectrum efficiency in b/s/Hz/\(\mathrm{{km}}^2\), and distance-related efficiency in (b m)/s/Hz/W, while we give out a comprehensive summary of optimization criteria for energy-efficient WANs. Secondly, we provide the taxonomy of various energy management schemes for the WANs covering all the layers of the protocol stack, specifically including the physical layer, medium access control (MAC) layer, network layer and cross-layer design. Importantly, we tend to discuss a range of energy-efficient MAC protocols proposed for the WANs, especially carrier sense multiple access with collision avoidance (CSMA/CA), the basic MAC protocol for WANs, and its potential energy management schemes. In each layer design, we note that the network energy consumption is always related with other performance indicators we can’t ignore, for instance the network lifetime, connection reliability, network throughput, and etc. By exploiting the performance improvement potentials from the dependence among the original protocols layer, we finally pay attention to the cross layer design. In one word, the guiding study of fundamental theory goes together with the energy management with a specific system target. Meanwhile, we point out the future research perspectives in energy management for WANs.