Doppler Effect Mitigation using Reconfigurable Intelligent Surfaces with Hardware Impairments

In this paper, we analyze the effects of different types of hardware impairments (HWI), including RIS-HWI, transceiver HWI, phase quantization errors and random failures, on vehicular communication system using reconfigurable intelligent surfaces (RIS) with Doppler mitigation. A closed-form expression for the received signal-to-noise-and-distortion ratio (SNDR) of an RIS-aided vehicular communication system with HWI is derived, and we also show that the average Doppler spread can be removed completely. The simulation results validate that RIS with HWI is able to bring promising average SNDR gain (e.g, 3.16 dB) of the received signal, while eliminating the average Doppler spread, and keeping the delay spread at a very low range. As a result, using the predictable positions of the vehicle, the phase shift set of RIS can be designed in advance, such that channel estimation is not necessary, resulting in lower implementation complexity.