A Simple Cascade Channel Estimation Method for UAV RIS-Enabled Millimeter Wave Transmissions

Abstract

Reconfigurable Intelligent Surfaces (RIS) is an emerging concept in Sixth Generation (6G) technologies. RIS can manipulate the wireless communication environment and provide virtual Line of Sight (LOS) links between a Base Station(BS) and User Equipment (UE) by controlling the coefficients of passive reflecting elements. RIS is a promising concept with its passive and low-cost nature. However, RIS-enabled transmission experiences double scattering and high path loss. Besides, it requires a massive number of elements in the millimeter-wave(mmWave) and sub-TeraHertz(THz), which makes channel estimation a complicated problem. There are quite a number of diverse methods in recent literature. In this work we assume a Unmanned Aerial Vehicle(UAV)-mounted RIS that provides a line of sight. We propose a simple cascade channel estimation method and compare its performance with that of a recently proposed channel estimation scheme. We perform comparisons, taking the overhead caused by Fifth Generation (5G) Low Density Parity Check (LDPC) coding and channel estimation overhead into account. Simulations show that our proposal achieves a much better spectral efficiency. © 2023 IEEE.