Enhancing Indoor mmWave Wireless Coverage: Small-Cell Densification or Reconfigurable Intelligent Surfaces Deployment?

Both reconfigurable intelligent surfaces (RISs) and ultra-dense (UD) small-cell (SC) base stations (BSs) are investigated for indoor mmWave wireless coverage enhancement. To explore which deployment strategy is more cost-effective, the costs of deploying both RISs and UD SCs are defined and calculated. Through jointly analyzing coverage probability and network cost in typical indoor environments, we conclude that the same network coverage can be achieved by multiple deployment strategies. To achieve certain level of coverage probability with the lowest network cost, a proper number of BSs are crucial for RIS-assisted networks.