Performance of Hybrid THz and Multiantenna RF System With Diversity Combining

Abstract

Recent studies investigate single-antenna radio frequency (RF) systems mixed with terahertz (THz) wireless communications. This article considers a two-tier system of THz for backhaul and multiple-antenna-assisted RF for the access network. We analyze the system performance by employing both the selection combining and maximal ratio combining receivers for the RF link integrated with the THz link using the fixed-gain amplify-and-forward protocol. We develop the probability density function and the cumulative distribution function of the end-to-end signal-to-noise ratio (SNR) of the dual-hop system over independent and nonidentically distributed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\alpha$</tex-math></inline-formula> – <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula> fading channels with a statistical model for misalignment errors in the THz wireless link. We use the derived statistical results to develop analytical expressions of the outage probability, average bit error rate, and ergodic capacity for the performance assessment of the considered system. We develop a diversity order of the system using asymptotic analysis in the high-SNR region, demonstrating the scaling of system performance with the number of antennas. We use computer simulations to show the effect of system and channel parameters on the performance of the hybrid THz-RF link with multiantenna diversity schemes.