In this paper, we develop a novel analytical framework for a three-dimensional (3D) indoor terahertz (THz) communication system. Our proposed model incorporates more accurate modeling of wall blockages via Manhattan line processes and precise modeling of THz fading channels via a fluctuating two-ray (FTR) channel model. We also account for traditional unique features of THz, such as molecular absorption loss, user blockages, and 3D directional antenna beams. Moreover, we model locations of access points (APs) using a Poisson point process and adopt the nearest line-of-sight AP association strategy. Due to the high penetration loss caused by wall blockages, we consider that a user equipment (UE) and its associated AP and interfering APs are all in the same rectangular area, i.e., a room. Based on the proposed rectangular area model, we evaluate the impact of the UE's location on the distance to its associated AP. We then develop a tractable method to derive a new expression for the coverage probability by examining the interference from interfering APs and considering the FTR fading experienced by THz communications. Aided by simulation results, we validate our analysis and demonstrate that the UE's location has a pronounced impact on its coverage probability. Additionally, we find that the optimal AP density is determined by both the UE's location and the room size, which provides valuable insights for meeting the coverage requirements of future THz communication system deployment.

翻译：本文针对三维室内太赫兹通信系统提出了一种新颖的分析框架。所提模型通过曼哈顿线过程实现了墙体遮挡的更精确建模，并采用波动双射线信道模型对太赫兹衰落信道进行精准建模。同时，我们考虑了太赫兹通信的传统独有特性，如分子吸收损耗、用户遮挡效应以及三维定向天线波束。此外，我们采用泊松点过程对接入点的位置分布进行建模，并采用最近视距接入点关联策略。鉴于墙体遮挡导致的高穿透损耗，我们假设用户设备与其关联接入点及干扰接入点均位于同一矩形区域（即房间）内。基于所提出的矩形区域模型，我们评估了用户设备位置对其关联接入点距离的影响。随后，通过分析干扰接入点产生的干扰并考虑太赫兹通信经历的FTR衰落，我们提出了一种可处理的方法来推导覆盖概率的新表达式。借助仿真结果，我们验证了理论分析的正确性，并证明用户设备的位置对其覆盖概率具有显著影响。此外，我们发现最优接入点密度由用户设备位置与房间尺寸共同决定，这为满足未来太赫兹通信系统部署的覆盖需求提供了重要参考依据。