Reconfigurable Intelligent Surface Configuration and Deployment in Three-dimensional Scenarios

The Reconfigurable Intelligent Surface (RIS) is seen as one of the most prospective technologies for next-generation networks. RIS can form virtual line-of-sight (LoS) link during non-line-of-sight (NLoS) transmission to improve system performance with low power consumption, especially for urban scenarios. In this paper, for an RIS-aided system, we extend the two-dimensional path-loss model to a more practical three-dimensional path-loss model. We further compare the system performance differences among RIS, relay and single-input single-output (SISO) systems. We also reveal proper deployment positions of RIS and derive the number of reflecting elements required under different constraints. Numerical results verify the complementarity between RIS and decode-and-forward (DF) relay. The performance of RIS-aided communication system can be significantly improved by optimizing RIS deployment locations and the number of reflecting elements.