Best effort communications with green metrics

The growth in energy demand coupled with global warming provide new trends in communication systems known as green radio. The main focus in green radio is to provide new techniques to save energy consumption. In this paper, a new concept, named ultra wide time (UWT), is proposed to define the lower asymptotic consumed energy to transmit a given amount of information. With UWT concept, minimization of energy consumption leads to infinite time of transmission. To overcome this drawback, and instead of energy minimization, we proposed to evaluate the energetic performance of communication systems with a new energy efficiency β, defined as the ratio between the asymptotic limit and the consumed energy. It is then possible to control the energetic consumption with finite time of transmission. The energy efficiency β is fixed in advance and the transmitter is then configured under this constraint. Both UWT and energy efficiency β are applied in parallel channel with best effort communications. Simulation results show that energetic gains of 20 dB can be reached in WiMAX configuration. This respects the "two order of magnitude lower transmission power" mentioned by the Wireless World Research Forum.