Millimeter wave (mmWave) has attracted considerable attention due to its wide bandwidth and high frequency. However, it is highly susceptible to blockages, resulting in significant degradation of the coverage and the sum rate. A promising approach is deploying distributed reconfigurable intelligent surfaces (RISs), which can establish extra communication links. In this paper, we investigate the impact of distributed RISs on the coverage probability and the sum rate in mmWave wireless communication systems. Specifically, we first introduce the system model, which includes the blockage, the RIS and the user distribution models, leveraging the Poisson point process. Then, we define the association criterion and derive the conditional coverage probabilities for the two cases of direct association and reflective association through RISs. Finally, we combine the two cases using Campbell's theorem and the total probability theorem to obtain the closed-form expressions for the ergodic coverage probability and the sum rate. Simulation results validate the effectiveness of the proposed analytical approach, demonstrating that the deployment of distributed RISs significantly improves the ergodic coverage probability by 45.4% and the sum rate by over 1.5 times.

翻译：毫米波因其宽带宽和高频特性而备受关注，然而极易受到障碍物阻挡，导致覆盖率和总速率显著下降。一种有前景的方案是部署分布式可重构智能表面（RIS），通过建立额外通信链路来缓解这一问题。本文研究了分布式RIS对毫米波无线通信系统覆盖概率和总速率的影响。具体而言，我们首先基于泊松点过程构建了包含障碍物、RIS及用户分布模型的系统模型；随后定义了关联准则，并推导了直接关联和通过RIS反射关联两种情形下的条件覆盖概率；最后利用坎贝尔定理和全概率定理将两种情形合并，得到了遍历覆盖概率和总速率的闭式表达式。仿真结果验证了所提分析方法的有效性，表明分布式RIS的部署可将遍历覆盖概率提升45.4%，总速率提升1.5倍以上。