Intelligent Reflecting Surface Enhanced User Cooperation in Wireless Powered Communication Networks

An intelligent reflecting surface (IRS) comprises a massive number of low-cost passive elements that can be controlled to reflect the incident signals into a structured output pattern. In this letter, we consider IRS-assisted user cooperation in a wireless powered communication network (WPCN), where two users harvest wireless energy and transmit information to a common hybrid access point (HAP). In particular, we exploit the use of IRS to enhance the energy efficiency in the wireless energy transfer (WET) phase and the spectral efficiency in the wireless information transmission (WIT) phase. We derive the maximum common (minimum) throughput performance by jointly optimizing the transmit time and power allocations of the two users and the passive array coefficients on reflecting the wireless energy and information signal. Simulation results show that the use of IRS can effectively improve the throughput performance of cooperative transmission in WPCNs.