Consider the problem of power control for an energy harvesting communication system, where the transmitter is equipped with a finite-sized rechargeable battery and is able to look ahead to observe a fixed number of future energy arrivals. An implicit characterization of the maximum average throughput over an additive white Gaussian noise channel and the associated optimal power control policy is provided via the Bellman equation under the assumption that the energy arrival process is stationary and memoryless. A more explicit characterization is obtained for the case of Bernoulli energy arrivals by means of asymptotically tight upper and lower bounds on both the maximum average throughput and the optimal power control policy. Apart from their pivotal role in deriving the desired analytical results, such bounds are highly valuable from a numerical perspective as they can be efficiently computed using convex optimization solvers.

Consider a battery limited energy harvesting communication system with online power control. Assuming independent and identically distributed (i.i.d.) energy arrivals and the harvest-store-use architecture, it is shown that the greedy policy achieves the maximum throughput if and only if the battery capacity is below a certain positive threshold that admits a precise characterization. Simple lower and upper bounds on this threshold are established. The asymptotic relationship between the threshold and the mean of the energy arrival process is analyzed for several examples.

We study power control for an energy harvesting communication system with independent and identically distributed Bernoulli energy arrivals. It is assumed that the transmitter is equipped with a finite-sized rechargeable battery and is able to look ahead to observe a fixed number of future arrivals. A complete characterization is provided for the optimal power control policy that achieves the maximum long-term average throughput over an additive white Gaussian noise channel.

We investigate the (forward) key capacity of a Gaussian state-dependent wiretap channel (G-SWC) paralleled with a public channel having capacity Cpϵ [0, ∞). This model consists of a sender, a main receiver, and a wiretapper. The channel state information (CSI) is an additive white Gaussian interference (AWGI) which is non-causally known at the sender. A lower bound (LB) on the key capacity is achieved by using a generalized version of the dirty paper coding (DPC) in which the transmitted signal is correlated with the interference. The correlation coefficient is to be determined by Cp. The achievable scheme is asymptotically optimum as Cp→ ∞. This optimum key capacity is also asymptotically achievable for any Cp≥ 0 in high signal to interference ratio (SIR) regime. In this regime, the public channel has negligible contribution in key generation. Generally, the CSI enhances the key capacity such that it exceeds the main channel capacity of the G-SWC in low SIR regime.

Key agreement problem over a discrete memoryless state-dependent wiretap channel (DM-SWC) is addressed in this paper. Three parties have access to the wiretap channel: One transmitter, an authorized receiver, and an illegal receiver. The transmitter fully knows channel state information (CSI) in a non-causal form, while each receiver has access to a sequence of side information (SI) correlated with the CSI. Further to the DM-SWC, the parties can also exploit a unilateral public channel with a given capacity from the transmitter to the receivers. We have obtained a lower bound (LB) on the key capacity. The LB achieves the key capacity when the capacity of the public channel exceeds a fixed finite value determined by the DM-SWC. For any DM-SWC, the key capacity is consequently achievable as the public channel capacity becomes unlimited. An upper bound (UB) on the key capacity is obtained when the legal receiver is less noisy than the wiretapper.