Unmanned Aerial Vehicle-Assisted Reconfigurable Intelligent Surface for Energy Efficient and Reliable Communication

Abstract

AbstractUnmanned aerial vehicle (UAV) is one of the airborne components, which can establish a flexible infrastructure to support seamless connectivity requirements of the sixth-generation (6G) standard. Modern UAVs are equipped with communication and signal processing capabilities. Hence, it can act as a base station or relay station to support reliable communication. In order to improve energy efficiency, reconfigurable intelligent surfaces (RIS) can be employed on UAVs or the communication chain. The physical parameters, such as phase shifts of reflecting units, can be adjusted to enhance the signal-to-noise ratio (SNR) through software control. RIS can directly provide the additional array gain without complex precoding and radio frequency (RF) level processing. Due to this, a smaller number of onboard antennas are sufficient for UAVs to offer the required array gain for users. In this work, intelligent and blind UAV-assisted RIS schemes are proposed to increase energy efficiency. In contradiction to the blind scheme, the knowledge of the dual-hop channel is assumed to be available at UAV in an intelligent UAV-assisted RIS scheme, which maximizes the SNR. The analytical closed-form average bit error probability (ABEP) expressions are derived to validate our claims. Through simulation results, it is observed that intelligent UAV-assisted RIS can convert wireless fading environment into superior communication environment, which can offer a low average bit error rate (ABER) at extremely low SNR conditions.KeywordsArray gainAverage bit error probability (ABEP)Average bit error rate (ABER)Blind UAV-assisted RISDiversity gainDual-hop communicationIntelligent UAV-assisted RISReconfigurable intelligent surfaces (RIS)Sixth-generation (6G)Unmanned aerial vehicle (UAV)