Low-RCS and Wideband Reflectarray Antenna With High Radiation Efficiency

Intelligent reflecting surface (IRS) is a promising new paradigm to achieve high spectral and energy efficiency for future wireless networks by reconfiguring the signal propagation via passive reflection. To reap potential gains of IRS, channel state information (CSI) essential, whereas estimation errors are inevitable in practice due limited training resources. In this paper, order optimize performance IRS-aided multiuser systems with imperfect CSI, we propose jointly design active transmit precoding at access point (AP) reflection coefficients each consisting not only conventional phase shift also newly exploited amplitude variation. First, achievable rate user derived assuming practical IRS method, which shows that interference CSI intricately related AP precoders, power during both data transmission. Then, single-user case, combining benefits penalty Dinkelbach method block successive upper-bound minimization (BSUM) penalized Dinkelbach-BSUM algorithm proposed maximizing transmission subjected errors; while dual decomposition (PDD)-based maximize users' weighted sum-rate. Simulation results presented validate effectiveness our algorithms as compared benchmark schemes. particular, useful insights drawn characterize effect control (with/without shift) on system under CSI.