## 1 Introduction
The authors derive expressions for the performance characteristics of this system, and then, through simulation results, state that this adaptive approach performs better compared to a single-link system. In [15], the authors investigate the potential of THz frequency bands for data transmissions between core networks and access points (AP) in next-generation wireless systems. They analyze a dual-hop THz-RF wireless system where an AP serves as a relay between the core network and the end-user equipment. The study employs a generalized end-to-end channel model with an independent and not identically distributed (i.ni.d.) fading for the THz and RF links, incorporating the \(\alpha-\mu\) distribution, pointing errors in the THz link, and an asymmetrical relay position. The authors derive a closed-form expression for the cumulative distribution function (CDF) of the E2E SNR, facilitating a generalized performance analysis over THz fading channels. Utilizing the derived CDF, they evaluate system performance using the DF protocol, deriving closed-form expressions for outage probability, SNR moments, average BER, and an the approximation of ergodic capacity. Additionally, they perform asymptotic analysis on the ergodic capacity, outage probability, and average BER in the high-SNR region, determining the system's diversity order. The study also examines the system using an i.i.d. model to provide analytical insights under various practical scenarios. Through simulation and numerical analysis, the study reveals significant effects of THz link fading parameters and a nominal impact of normalized beam-width on the performance of the relay-assisted THz-RF system. In [16], the authors examined the performance of a mixed THz/FSO wireless transmission system, accounting for the joint effects of channel fading and pointing errors in both THz and FSO links. Utilizing a semi-blind amplify-and-forward (AF) protocol, they derived the exact expressions for outage probability, average BER, and average channel capacity. To provide further insights, asymptotic expressions for outage probability and average BER were also presented, revealing that the diversity gain is influenced by the channel fading and pointing errors of both links. The study extended to consider hardware impairments, deriving the outage probability for systems with non-ideal hardware, and further explored multi-antenna scenarios by obtaining asymptotic outage probability expressions. The numerical results illustrated that path loss, channel fading, pointing errors, and hardware impairments significantly degrade system performance, highlighting critical factors to address in the design and implementation of THz/FSO wireless systems. In [17], the authors investigate a hybrid FSO/THz-based backhaul network designed to deliver high-data-rate, reliable communication to terrestrial mobile users (MUs) operating in millimeter-wave (mmWave) bands. The FSO link faces challenges from atmospheric turbulence and pointing errors, while the THz link is impacted by high path loss, small-scale fading, and misalignment errors. To mitigate back-and-forth switching effects, a soft switching method is introduced at the AP to select signals from the hybrid FSO/THz link, and a performance comparison is conducted with hard switching methods. The study employs selective DF relaying at the AP, deriving closed-form expressions for individual link outage probability, E2E outage probability, asymptotic outage probability, ergodic capacity, and generalized average BER. The impact of parameters such as atmospheric turbulence, pointing/misalignment errors, link distance, atmospheric attenuation/path loss, the fading parameters of the THz and access links, and the number of antennas on network performance is analyzed. The results demonstrate that an appropriate switching method can significantly enhance the rate and reliability of backhaul links while maintaining a minimal switching overhead, thereby optimizing the performance of the integrated FSO/THz network.