On the Fraction of LoS Blockage Time in mmWave Systems with Mobile Users and Blockers

Today, one of the emerging trends for the next generation (5G) networks is utilizing higher frequencies in closer premises. As one of the enablers, small cells appear as a cost-effective way to reliably expand network coverage and provide significantly increased capacity for end users. The ultra-high bandwidth available at millimeter (mmWave, 30–300 GHz) and Terahertz (THz, 0.3–3 THz) frequencies can effectively realize short-range wireless access links in small cells. Those technologies could also be utilized for direct communications for users in proximity. At the same time, the performance of mobile wireless systems operating in those frequency bands depends on the availability of line-of-sight (LoS) between communicating entities. In this paper, we estimate the fraction of LoS time for randomly chosen node moving according to different mobility models in a field of N moving blocking nodes for both base station and device-to-device (D2D) connectivity scenarios. We also provide an extension to the case of a random number of moving blockers. The reported results can be further used to assess the amount of traffic offloaded to other technologies having greater coverage, e.g., LTE.