Abstract
The wireless energy harvesting (EH) technique is regarded as a new way to provide an energy supply for energy-constrained cognitive relay networks (CRNs). A novel wireless EH cognitive multi-user relay network (CMRN) for the underlay protocol is investigated in this paper. In this system, there are multiple primary users (PUs) and multiple secondary users (SUs). The SUs can share the licensed spectrum and harvest energy from ambient signals. The problems of multiple relay selection by the SUs and of finding the optimal EH ratio are considered. We analytically derive the exact expression of the throughput of a secondary network. In it, there are four constraints: for the permitted peak interference with each primary transmitter (PT); for the sum interference for each PT; that the transmit power of secondary source nodes (SSNs) and secondary relays (SRs) should be less than the energy harvested; and that each secondary source node/secondary destination node (SSN-SDN) pair can only choose one SR. To obtain the optimal performance of the secondary network’s throughput, we should optimize the multiple relay selection scheme and the EH ratio. Actually, it is a classic integer optimization problem to design an optimal multiple relay selection scheme. However, the selection of the optimal EH ratio is a continuous optimization problem. The joint multiple relay selection and time slot allocation is a classical hybrid optimization problem. So, we propose a novel quantum sine cosine algorithm (QSCA) for resolving the difficulty with optimization of multiple relay selection and the EH ratio. Our simulation results verify our proposed solution by showing the influence of different parameters for the proposed model and by demonstrating good performance under the QSCA.
Highlights
With the increasing demand for wireless transmission and green communications, the efficiency of both spectrum and energy has been an essential concern for wireless communications [1]–[3]
We show the impact on the secondary network based on different system parameters
To further study the performance of a cognitive multiuser relay network (CMRN), we derived an analytical expression for the throughput of the secondary network
Summary
With the increasing demand for wireless transmission and green communications, the efficiency of both spectrum and energy has been an essential concern for wireless communications [1]–[3]. It is necessary to investigate an optimal multiple relay selection scheme for multiple SUs in an underlay network Existing works, such as that by Liu et al [26], only considered a fixed time slot structure model, and could not obtain optimal EH CRN system parameters for improving the performance of the communications system. The proposed method uses both licensed bands and unlicensed bands, which is different from traditional wireless energy harvesting, but they did not consider CRNs. In order to overcome the limitations in the existing methods and to obtain a more extensive application for the actual scenarios, it is necessary to design a novel wireless EH CMRN system model where there are multiple PUs and multiple SUs. For the model investigated in this paper, the SUs share the same licensed spectrum with the PUs. There are multiple relays for the secondary users to select for transmitting their own information.
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