Now, more than ever, the time to hasten the efforts made to reduce the energy consumption, especially in the field of radio communications has come. Wireless transmission was often blamed as being energy inefficient. It is well known that, in radio communications, approximatively 80% of the consumed energy is used only to maintain the network connections during standby periods. Moreover, the number of connected devices is continuously growing: as estimated by the International Energy Agency, in 2030 the number of connected devices will be multiplied by eight and, as a consequence, the energy consumption will double.