  Wireless networks with energy harvesting battery powered nodes are quickly
emerging as a viable option for future wireless networks with extended
lifetime. Equally important to their counterpart in the design of energy
harvesting radios are the design principles that this new networking paradigm
calls for. In particular, unlike wireless networks considered up to date, the
energy replenishment process and the storage constraints of the rechargeable
batteries need to be taken into account in designing efficient transmission
strategies. In this work, we consider such transmission policies for
rechargeable nodes, and identify the optimum solution for two related problems.
Specifically, the transmission policy that maximizes the short term throughput,
i.e., the amount of data transmitted in a finite time horizon is found. In
addition, we show the relation of this optimization problem to another, namely,
the minimization of the transmission completion time for a given amount of
data, and solve that as well. The transmission policies are identified under
the constraints on energy causality, i.e., energy replenishment process, as
well as the energy storage, i.e., battery capacity. The power-rate relationship
for this problem is assumed to be an increasing concave function, as dictated
by information theory. For battery replenishment, a model with discrete packets
of energy arrivals is considered. We derive the necessary conditions that the
throughput-optimal allocation satisfies, and then provide the algorithm that
finds the optimal transmission policy with respect to the short-term throughput
and the minimum transmission completion time. Numerical results are presented
to confirm the analytical findings.
