On Information and Energy Cooperation in Energy Harvesting Cognitive Radio

TL;DR

This paper explores joint information and energy cooperation between energy harvesting primary and secondary users, proposing an optimal power policy algorithm that enhances cooperation chances and primary rate performance.

Contribution

It introduces a novel framework for two-level cooperation in energy harvesting cognitive radio, including an optimal offline power control algorithm and analysis of finite battery effects.

Findings

Joint cooperation increases cooperation probability.

Energy sharing improves primary user rate.

Finite battery constraints impact cooperation dynamics.

Abstract

This paper considers the cooperation between primary and secondary users at information and energy levels when both users are energy harvesting nodes. In particular, a secondary transmitter helps relaying the primary message, and in turn, gains the spectrum access as a reward. Also, the primary transmitter supplies energy to the secondary transmitter if the latter is energy-constrained, which facilitates an uninterrupted cooperation. We address this two-level cooperation over a finite horizon with the finite battery constraint at the secondary transmitter. While promising the rate-guaranteed service to both primary and secondary users, we aim to maximize the primary rate. We develop an iterative algorithm that obtains the optimal offline power policies for primary and secondary users. To acquire insights about the structure of the optimal solution, we examine specific scenarios. Furthermore, we investigate the effects of the secondary rate constraint and finite battery on the primary rate and the probability of cooperation. We show that the joint information and energy cooperation increases the chances of cooperation and achieves significant rate gains over only information cooperation.