Performance Optimization Algorithm Design For Swipt System With Intelligent Reflecting Surface

Intelligent reflecting surface(IRS)is a promising technology that can achieve spectrum and energy efficient wireless communication in the forthcoming fifth-generation(5G)mobile communication network.Meanwhile,simultaneous wireless information and power transfer(S WIPT)effectively answer to the unsustainable energy supply problem of electronic equipment and energy-constrained mobile networks.Combining the above technologies,aiming at the low efficiency of wireless power transmission in long distance communication system,we design the system model and optimization scheme.First,a single-user IRS-SWIPT wireless communication system is designed in this paper,where a power splitting receiver is considered at the user node.Under the transmit power constraint at the multi-antenna access point(AP)and the receive energy constraint at the user nodes,we formulate a problem to maximize the user's information transmission rate by jointly optimizing the transmit beamforming by active antenna array at the AP and the reflect beamforming by passive phase shifters at the IRS.Using the idea of semi-definite relaxation(SDR),the problem is solved by alternating iteration algorithm.In order to reduce the computation complexity,a low-complexity algorithm based on channel parallelization and singular value decomposition theory is proposed.Finally,the user's information transmission rate is calculated under different algorithms by simulation,respectively,which verify the validity of the theoretical analysis.Second,considering the actual application scenarios,we designed a multi-user IRS-SWIPT communication system for the situation where a multi-antenna AP provides services to multiple users at the same time.There is a problem of information interference between users in a multi-user system.To ensure that all users can communicate normally,we take the transmit power at the multi-antenna AP and the received energy at user nodes as constraints,formulate a new problem to maximize the minimum of users' signal-to-interference-plus-noise-ratio(SINR).For the purpose of addressing this nonconvex problem,a Dinkelbach-type algorithm is proposed.Finally,the effectiveness of the proposed scheme is proved through simulation results.