On the Capacity of Energy Harvesting Communication Link

We consider an energy harvesting point-to-point communication system where the transmitter is powered by an energy arrival process and is equipped with a battery of finite capacity B-max, which could be used for saving energy for future use. We assume a discrete i.i.d. energy arrival process where at each time step, energy of amount A(i) is harvested with probability p(i) for all i is an element of {1, 2, ..., K} independent of the other time steps. We provide upper and lower bounds on the capacity of this channel. These bounds are shown to be within a constant gap for K <= 3 for all parameters, and for K > 3 when the battery capacity Bmax is small or large enough, where this constant does not depend on any energy or battery parameters.