## 3 Related Work
### Power Control in THz Communications  
In [22], a lone UAV is designated to serving ground users via the THz frequency band. However, the inherent unpredictability of the THz channel poses new challenges in optimizing UAV positioning, user power levels, and bandwidth distribution. Consequently, it is imperative to devise a fresh framework for deploying UAVs within THz wireless systems. This task is formally framed as an optimization challenge with the aim of minimizing overall transmission delays for both uplink and downlink communication between the UAV and ground users. This objective is achieved through the simultaneous optimization of UAV deployment, transmit power, and user bandwidth. Given the critical significance of communication latency, particularly in emergency contexts, addressing this nonconvex delay minimization problem demands the development of an alternating algorithm. This algorithm iteratively tackles three subproblems: location optimization, power control, and bandwidth allocation. Again, this is a cross-layer approach. This paper [23] introduces a secure UAV-relay mobile system operating in sub-THz bands for cognitive networks. The study accounts for path loss effects and examines the performance of a UAV relay that receives data from a base station (SBS) and transmits it to a secondary user (SU), while minimizing interference from primary users (PUs) and eavesdroppers. To achieve the goal of maximizing the secrecy rate in UAV communication, an optimization problem is formulated, incorporating constraints such as UAV velocity, elevation, maximum transmission power, information causality, and interference temperature (IT). The primary optimization challenge is divided into two subproblems, and an alternative algorithm is proposed to solve it efficiently. Extensive analysis and performance results demonstrate that the proposed algorithm significantly enhances physical layer security in UAV-relay communications within the sub-THz spectrum. In [24], the authors present a pioneering operational framework for the IEEE standard [25] 802.15, designed to curtail power transmission requirements while adhering to specified data rate benchmarks. This leads to a decreased reliance on battery capacity or antenna size to uphold consistent communication link robustness. Their method involves the meticulous optimization of power levels, modulation schemes, and channel allocations to effectively minimize total transmitted power while upholding a minimum quality-of-service standard. Additionally, our solution incorporates considerations for the influence of humidity on system performance, providing a holistic approach tailored to practical, real-world scenarios. In this paper, we see a coherent and complete approach that does take into account a number of parameters that influence the communication. In [26], the paper presents a theoretical framework for device-to-device (D2D) communication operating in the THz band. They derive closed-form formulas for data rates, outage probability, and energy efficiency. Through simulations, they illustrate improvements in both data rates and energy efficiency, along with a decrease in D2D communication outage probability within the THz spectrum. Notably, they observe an 86% increase in energy efficiency with a transmission power of 19 dBm. Furthermore, optimal transmission power allocation across 50 resource blocks results in an 87% improvement in energy efficiency. In [27], the study delves into THz wireless communication among UAVs, focusing keenly on the diverse fading channels pivotal for modeling THz communication networks. It meticulously analyzes the performance of UAV communications within THz networks, accounting for critical structural aspects, wireless channel parameters, and transmission characteristics essential for evaluating wireless technology effectiveness. The analysis encompasses a comprehensive range of fading channels, including Nakagami-m, Rician, Weibull, Rayleigh, and log-normal fading.