Resource Allocation and Fairness in Wireless Powered Cooperative Cognitive Radio Networks

TL;DR

This paper proposes an optimal resource allocation scheme for wireless powered cooperative cognitive radio networks, balancing sum-throughput and fairness among secondary users through various allocation strategies.

Contribution

It introduces a sum-throughput optimal resource allocation scheme and explores three fairness-enhancing resource allocation strategies.

Findings

The STORA scheme maximizes secondary sum-throughput under primary rate constraints.

Fairness can be improved using equal, minimum throughput, or proportional time allocations.

Trade-offs exist between sum-throughput and fairness among secondary users.

Abstract

We integrate a wireless powered communication network with a cooperative cognitive radio network, where multiple secondary users (SUs) powered wirelessly by a hybrid access point (HAP) help a primary user relay the data. As a reward for the cooperation, the secondary network gains the spectrum access where SUs transmit to HAP using time division multiple access. To maximize the sum-throughput of SUs, we present a secondary sum-throughput optimal resource allocation (STORA) scheme. Under the constraint of meeting target primary rate, the STORA scheme chooses the optimal set of relaying SUs and jointly performs the time and energy allocation for SUs. Specifically, by exploiting the structure of the optimal solution, we find the order in which SUs are prioritized to relay primary data. Since the STORA scheme focuses on the sum-throughput, it becomes inconsiderate towards individual SU throughput, resulting in low fairness. To enhance fairness, we investigate three resource allocation schemes, which are (i) equal time allocation, (ii) minimum throughput maximization, and (iii) proportional time allocation. Simulation results reveal the trade-off between sum-throughput and fairness. The minimum throughput maximization scheme is the fairest one as each SU gets the same throughput, but yields the least SU sum-throughput.