Abstract: Based on Lyapunov optimization framework,an online power control scheme is proposed to maximize the long-term average transmission rate for wireless communication systems with energy harvesting devices at the transmitter. The power control algorithm takes into account the energy loss in the charging and discharging processes of the rechargeable battery,and uses a nonlinear mathematical model to describe the charging and discharging efficiency. The constraint condition of battery power is transformed into the stable requirement for the energy virtual queue,and the negative value of the transmission rate that needs to be maximized is taken as the penalty term. Based on the current channel state and battery energy state,the average transmission rate is maximized by minimizing the drift-plus-penalty under the constraint of the harvested energy. Simulation results show that the performance of the proposed algorithm is slightly lower than that of the off-line water-filling algorithm,but is much better than those of the greedy algorithm and the half-power algorithm. In addition, the proposed algorithm also outperforms the existing algorithm that adopts Lyapunov method without considering the chargeing and discharging efficiency.

Key words: energy harvesting, Lyapunov optimization framework, online power control, charging/discharging efficiency