ABSTRACT
For a long time, the problem of energy consumption mainly concerned autonomous, embarked, or mobile communication terminals. Over the past two decades, designing energy-efficient communication terminals has become a more and more important issue. Concepts such as “green communications” have recently emerged in the literature, e.g., [10], [16] etc. Nowadays, with the existence of large networks involving both fixed and mobile terminals, the energy consumed by the fixed infrastructure has also become a central issue for communications engineers [6]. This chapter presents some of the literature in this framework. More specifically, this is a guide for researchers and engineers on how to devise power control and power allocation schemes in green wireless networks. Among pioneering works on energy-efficient power control there are the works of Goodman [28], [21], [14], [27] and [9] and others like [42]. Therein, the authors define the energy-efficiency of a communication as the ratio between the net data rate (called goodput) and the radiated power; the corresponding quantity is a measure of the average number of bits successfully received per joule of energy consumed at the transmitter. This metric has been used in many works. For example, in [33] it is applied to the problem of distributed power allocation in multi-carrier CDMA (code division multiple access systems) systems. In [34], it is used to model the users delay requirements in energy-efficient systems. In [2], it is re-interpreted as a capacity per unit cost1 measure in MIMO (multiple input multiple output) systems for static and fast fading channels. The use of MIMO in communications brings forth two significant gains characterized as the diversity gain (due to having different channel conditions at different antennas like in MISO) and the multiplexing gain.
