Energy and throughput tradeoff in temporal spectrum sharing

It is envisaged that diverse types of short-range wireless systems coexist in shared spectrum in a near future. For low-power systems, throughput and energy efficiency are two design objectives that often conflict with each other. In this paper, we investigate the tradeoff between the throughput and the energy efficiency for a data-hungry but battery-driven low-power network which opportunistically shares radio spectrum in temporal domain. We provide a mathematical framework that determines the optimum frame lengths for the different objectives, and analyze the tradeoff. To this purpose, we propose an energy consumption model that reflects the characteristics of low-power transceivers including power consumption at the receiver side. Numerical results show that the optimum frame length for energy efficiency results in significant loss in throughput, and vice versa. This suggests that the transmission duration of the opportunistic network should be chosen depending on the prime system objective.