Optimal Utilization of a Cognitive Shared Channel with a Rechargeable Primary Source Node

TL;DR

This paper analyzes how to optimally share a cognitive radio channel between a primary energy-constrained node with a rechargeable battery and a secondary node, maximizing secondary throughput while ensuring primary stability.

Contribution

It introduces a new cognitive sharing scheme allowing the secondary to transmit simultaneously with the primary, optimizing the probability to maximize secondary throughput under stability constraints.

Findings

Derived the maximum stable throughput region for both finite and infinite battery capacities.

Showed that simultaneous transmission with the primary can enhance secondary throughput.

Provided conditions under which the secondary can transmit without destabilizing the primary.

Abstract

This paper considers the scenario in which a set of nodes share a common channel. Some nodes have a rechargeable battery and the others are plugged to a reliable power supply and, thus, have no energy limitations. We consider two source-destination pairs and apply the concept of cognitive radio communication in sharing the common channel. Specifically, we give high-priority to the energy-constrained source-destination pair, i.e., primary pair, and low-priority to the pair which is free from such constraint, i.e., secondary pair. In contrast to the traditional notion of cognitive radio, in which the secondary transmitter is required to relinquish the channel as soon as the primary is detected, the secondary transmitter not only utilizes the idle slots of primary pair but also transmits along with the primary transmitter with probability $p$. This is possible because we consider the general multi-packet reception model. Given the requirement on the primary pair's throughput, the probability $p$ is chosen to maximize the secondary pair's throughput. To this end, we obtain two-dimensional maximum stable throughput region which describes the theoretical limit on rates that we can push into the network while maintaining the queues in the network to be stable. The result is obtained for both cases in which the capacity of the battery at the primary node is infinite and also finite.