Abstract-We consider wireless transmission over fading channel powered by energy harvesting and storage devices. Assuming a finite battery storage capacity, we design an online power control strategy aiming at maximizing the long-term timeaveraged transmission rate under battery operational constraints for energy harvesting. We first formulate the stochastic optimization problem, and then develop techniques to transform this problem and employ techniques from Lyapunov optimization to design the online power control solution. In particular, we propose an approach to handle unbounded channel fade which cannot by directly dealt with by Lyapunov framework. Our proposed algorithm determines the transmission power based only on the current energy state of the battery and channel fade conditions,without requiring any knowledge of the statistics of energy arrivals and fading channels. Our online power control solution is a three-stage closed-form solution depending on the battery energy level. It not only provides strategic energy conservation through the battery energy control, but also reveals an opportunistic transmission style based on fading condition, both of which improve the long-term time-averaged transmission rate. We further characterize the performance bound of our proposed algorithm to the optimal solution with a general fading distribution. Simulation results demonstrate a significant performance gain of our proposed online algorithm over alternative online approaches.

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We consider data transmission with energy harvesting and storage devices over wireless fading channel. We design an online power control strategy aiming at maximizing the long-term time-averaged data rate, given finite battery storage and operation constraints. Through problem transformation and Lyapunov optimization technique, we develop an online algorithm to determine transmit power based on the current energy level of the battery and channel fade condition. Our power solution does not rely on any knowledge of the statistics of energy arrivals and fading channel. It is provided in closed-form which not only provides insight to the energy management and transmission control actions, but also has minimum complexity for implementation. We further bound the performance of our proposed algorithm to that of the optimal solution. Simulation results demonstrate significant performance gain of the proposed strategy over the greedy approach.

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This paper concerns transmission over a two-hop quasi-static Rayleigh block fading channel in which communication is made through the use of a Decode and Forward (DF) relay. It is assumed that the channel state information (CSI) associated with both hops are only available at the corresponding receivers, while they are unknown to the transmitters. Considering an outage event occurs if the destination can not receive a target rate, the optimal achievable average rate-outage probability tradeoff curve is obtained through the use of a multi-layer code at both hops, termed the broadcast strategy. In order to maximize the average rate, we propose an optimum power allocation scheme of both hops. Numerical results show that the maximum achievable average rate for the specific outage probability is obtained when the threshold layer of both hops are equal.