Energy-aware adaptive OFDM systems

An effective way of reducing the energy consumption without affecting the quality of service is by adapting to the channel conditions. In this paper we describe one such scheme for an OFDM system using space division multiplexing technology. We consider tuning parameters such as modulation level and number of antennas that are considered by WiMax and LTE, as well as number of sub-carriers, peak to average power ratio, interpolation, pilot length and cyclic prefix. We describe a two-phase procedure for determining the parameter settings for minimizing energy consumption given the transmission rate, error performance and channel conditions for frequency selective fading channels. Our results show that we can reduce energy by an additional 5%-30% compared to systems that can only adapt modulation order and number of antennas.