Resource Allocation and Fairness in Wireless Powered Cooperative Cognitive Radio Networks

Abstract

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 sumthroughput 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.

Outage Probability Analysis in Power-Beacon Assisted Energy Harvesting Cognitive Relay Wireless Networks

“…Among different cognitive paradigms, an underlay mode in which SN users transmit in the same band with the primary transmitters simultaneously subject to an interference constraint at the primary receiver is the simplest and is easy to implement in practice. Therefore, many studies have considered energy harvesting for underlay CR networks; see, for example, [18][19][20][21][22]. In [18], the authors analyzed the outage probability and spatial throughput of the SN users.…”

“…In [19], a harvested energy-throughput trade-off optimization problem was formulated and a closed-form solution was obtained. Optimal resource allocation (i.e., time sharing and power) for EH-based CR networks was considered in [20,21]. Also, an extension to joint time and power allocation for maximal sum-throughput in multiuser EH-based CR networks was studied in [22].…”

A joint sensing and transmission power control policy for RF energy harvesting cognitive radio networks

“…In Lee and Zhang, 11 sum-throughput maximization problem is studied for overlay energy harvesting CRNs, wherein a hybrid access point (HAP) cooperatively sends a PU's data during its wireless energy transfer phase, and then decodes SUs' messages in the wireless information transmission phase. Kalamkar et al 12 proposed a cooperation protocol, where multiple SUs that harvest energy from a PU and an HAP are responsible for relaying the primary transmission. Moreover, relay selection and the fairness among SUs are also taken into account in Kalamkar et al 12 In underlay paradigms, SUs consume the harvested energy to transmit simultaneously with the primary network as long as the interference caused to the PUs can be controlled properly.…”

“…Kalamkar et al 12 proposed a cooperation protocol, where multiple SUs that harvest energy from a PU and an HAP are responsible for relaying the primary transmission. Moreover, relay selection and the fairness among SUs are also taken into account in Kalamkar et al 12 In underlay paradigms, SUs consume the harvested energy to transmit simultaneously with the primary network as long as the interference caused to the PUs can be controlled properly. In Lee and Zhang, 11 sum-throughput maximization is studied for underlay energy harvesting CRNs, wherein an HAP and energy harvesting SUs share the same spectrum for downlink wireless energy transfer and uplink wireless information transmission with a PU as long as the interference to the PU is below a prescribed threshold.…”

“…Kalamkar et al proposed a cooperation protocol, where multiple SUs that harvest energy from a PU and an HAP are responsible for relaying the primary transmission. Moreover, relay selection and the fairness among SUs are also taken into account in Kalamkar et al…”