The Mobile Blockers Impact on RISs Aided mmWave/THz Communication Systems

Abstract

Recently, reconfigurable intelligent surfaces (RISs) aided millimeter wave (mmWave) and terahertz (THz) communication systems have attracted interest as enablers for 5G and beyond networks. Although the static blockers’ impact can be eliminated by the optimal deployment of RISs, the effect of dynamic and self-blockage can only be reduced. First, due to mobile blockers and the user equipment (UE) itself, the RIS-UEs links can be blocked as well as the base station (BS)-UEs links. Second, in dense environments, all links to the UE can be blocked simultaneously causing a low received power. Furthermore, the dynamic blockers frequent interruptions and duration of blockages have a vital impact on the UE quality of service (QoS). Consequently, to tackle these points, in this paper, we derive an analytical dynamic blockage model to deduce various blockage metrics, i.e., blockage probability, frequency, and duration, in RISs aided systems considering all BSs-UE and RISs-UE links are not exposed to static or selfblocking. Moreover, we discuss the minimum required BSs/RISs density to guarantee UE QoS demands, e.g., link reliability and end-to-end latency, for beyond 5G network applications. Furthermore, we study the effects of the network specifications, e.g., BSs and RISs heights, communication range, and blockers density, on the required BSs/RISs density. Additionally, based on simulation analysis, we investigate the network performance, considering the blockage, in terms of spectral efficiency and energy efficiency. Our results prove that the RISs aided networks can be designed to satisfy the UE QoS requirements for serving different applications.

Keywords

• Reconfigurable intelligent surfaces
• 5G and beyond networks
• mobile blockers
• dynamic blocking
• reliability
• mmWave