A Performance Study of Relay-Assisted Double-Hop Hybrid RF-THz Wireless Systems

Abstract

This paper quantifies and evaluates the performance of a unique system model that offers end-to-end connectivity from a stable source to flying drones. Specifically, we examine a relay-assisted double-hop hybrid radio frequency (RF)-terahertz (THz) uplink wireless communication system. Exact analytical expressions of the cumulative distribution function, probability density function, characteristic function, and nth moment of the end-to-end signal-to-noise ratio of the system under consideration are obtained in the form of univariate Fox’s H-function (UFH). Rayleigh fading is employed to model the RF link, while the joint effect of the deterministic path loss, fluctuating two-ray fading, and recently introduced alignment error model is utilized to characterize the THz transmission link with fixed-gain amplify-and-forward relaying. Utilizing these statistical expressions, crucial performance indicators like outage probability (OP) and average bit error rate (ABER) are calculated in terms of the UFH. For a comprehensive insight into the system performances, we conduct the asymptotic analysis for both the OP and ABER and determine the diversity order of the system. Furthermore, a closely estimated upper bound on the average channel capacity (ACC) is provided. The impact of various design parameters is examined on the system performances in terms of the OP, ABER, and ACC.