Research On Collaborative Communication System Based On WPCN

With the advent of Wireless Powered Communication Network(WPCN),a new energy supply solution is available for wireless communication devices deployed in modern communication networks.This technology is based on the wireless energy harvesting(EH)technology,where the system maintains its sustainable operation by harvesting radio frequency(RF)energy signals.However,there are still lots of deficiencies in the current research on WPCN,for example,low energy transfer efficiency,no guarantee for the fairness of user information transfer,limited system throughput,etc.The emergence of Non-Orthogonal Multiple Access(NOMA)and Intelligent Reflecting Surface(IRS)technologies provides a new research direction to improve the performance of WPCN.NOMA technology can effectively improve the spectrum utilization efficiency and the fairness of the system.As a new collaborative communication technology,IRS technology can effectively improve the overall operation efficiency of WPCN by adjusting its own phase and reflecting the incident signals.Based on the above analysis,the main research contents and innovations of this paper are as follows:1.Consider the deployment of IRS in an existing WPCN scenario with joint optimization of IRS and conventional multi-antenna power station(PS).First,a WPCN system model based on NOMA and assisted by IRS is constructed,and a non-convex optimization problem about the maximum throughput of the system is proposed.In this paper,the block coordinate descent(BCD)technology is applied to alternately optimize the phase of IRS,beamforming of PS,energy transfer and information transfer time allocation of the system modules to derive an optimal solution to maximize the total throughput of this system.Finally,the positive impact of IRS on improving the system performance of WPCN is further explored.2.Considering that certain Successive Interference Cancellation(SIC)constraints should be satisfied at the information receiving end when NOMA technology is employed,a WPCN system model with IRS-NOMA based on user clustering is constructed.The maximum throughput optimization problem of this system is proposed under the condition that the information receiver can correctly detect and decode the user information.Due to the non-convexity of the problem,various optimization algorithms such as semidefinite relaxation(SDR)are applied in this paper to jointly optimize the effective phase shift of IRS in each time slot of the system,the information transmit power of users in the cluster and time allocation scheme of the system.Finally,an optimal solution to the total throughput of the system is found.Especially,the reason why IRS can improve the system performance of WPCN is further revealed by numerical simulation.There are 22 figures,0 tables and 73 references.