Delay Optimal Scheduling for Energy Harvesting Based Communications

TL;DR

This paper develops an optimal scheduling policy for energy harvesting communication systems that balances delay and power consumption by prioritizing harvested energy and judiciously using a reliable energy source under an average power constraint.

Contribution

It introduces a threshold-based scheduling scheme optimized via Markov chain modeling and linear programming, addressing delay-power tradeoffs in energy harvesting communications.

Findings

Optimal threshold-based policy derived for energy and data queue management.

The scheme effectively balances delay and power consumption from the reliable energy source.

Simulation results confirm the theoretical optimality and performance benefits.

Abstract

Green communication attracts increasing research interest recently. Equipped with a rechargeable battery, a source node can harvest energy from ambient environments and rely on this free and regenerative energy supply to transmit packets. Due to the uncertainty of available energy from harvesting, however, intolerably large latency and packet loss could be induced, if the source always waits for harvested energy. To overcome this problem, one Reliable Energy Source (RES) can be resorted to for a prompt delivery of backlogged packets. Naturally, there exists a tradeoff between the packet delivery delay and power consumption from the RES. In this paper, we address the delay optimal scheduling problem for a bursty communication link powered by a capacity-limited battery storing harvested energy together with one RES. The proposed scheduling scheme gives priority to the usage of harvested energy, and resorts to the RES when necessary based on the data and energy queueing processes, with an average power constraint from the RES. Through twodimensional Markov chain modeling and linear programming formulation, we derive the optimal threshold-based scheduling policy together with the corresponding transmission parameters. Our study includes three exemplary cases that capture some important relations between the data packet arrival process and energy harvesting capability. Our theoretical analysis is corroborated by simulation results.