Contents I. Introduction
With the even exploding amount of data traffic recently, the power consumption of wireless communication industry as well as the corresponding operational expenditure (OpEx) greatly threaten the profits of the operators. In addition, the pressure of environmental protection from the governments and publics results in more strict regulations on the energy consumption and CO2 emission. Hence, the energy efficient transmission technologies become one of the most important research topics and attract a lot of research projects and fundings, including Mobile Virtual Centre of Excellence (MVCE) 'Green Radio’ project [1] and 'Cool Silicon’ program targeting for low-power chip and network solutions [2], [3].
