Optimal Transmission Policies for Energy Harvesting Transmitter with Hybrid Energy Source in Fading Wireless Channel

Optimal energy scheduling problem for single-user wireless communication system in fading channel is studied in this paper. In this schedule, the transmitter is powered by hybrid energy sources including both the conventional grid and an energy harvester collecting energy from nature and storing energy in a rechargeable battery. In this system, data arrival process, energy harvesting process and channel state are all time-varying and possibly unpredictable. our objective is to develop policies of transmission power to minimize the additional energy consumption from the non-renewable energy source with the constraint of data queue stability and available energy harvested. We propose an online simple optimal algorithm which provides insight into how to efficiently utilize the energy supplied by the energy harvester. We utilize the technique of Lyapunov optimization to exploit energy efficient scheduling of the transmitter by adaptively adjusting transmission power, while at the same time provided a delay guarantee less than the maximum delay spent in the data queue. The challenge in this work is to provide an efficiently low complexity algorithm without knowing priori information of probability distribution. Finally, Simulation results of this algorithm show substantial reduction of energy from the non-renewable source ‘compared to two simple greedy algorithm. Key–Words: Energy harvesting, Lyapunov optimization, Optimal transmission policy, Hybrid energy source, Wireless communication.