Performance Evaluation of IRS-Assisted Intra-cell Handover in Vision-Aided mmWave Networks

Millimeter wave (mmWave) bands come with a deployment challenge of signal degradation when an obstacle blocks the line of sight (LOS) link. This paper proposes an intra-cell proactive handover (PHO) framework utilizing links from an intelligent reflective surface (IRS) to assist a 60GHz mmWave transmitter. Empowered by vision-aided wireless communication (VAWC) the PHO is aiming to replace a blocked LOS link with an IRS-assisted link. Evaluation of IRS-assisted link performance during the HO scenario is conducted to establish a solid understanding of deployment requirements and limitations. Estimations of the received signal strength indicator (RSSI) were performed to compare IRS-assisted links in the blocked area and LOS links in the absence of a blockage event. Results showed that for an IRS to provide a comparable signal level to the original LOS link, beam focusing must be the operating mode. IRS-assisted PHO scenarios were evaluated based on a range of IRS elements (64, 100 and 1000) to compare between the two links. Signal drop was between 30 to 15 dBm depending on the number of IRS elements and user location. The gap in signal level was further reduced to 10-5 dBm by increasing the number of antenna elements in the uniform linear array (ULA) sector transmitting to the IRS. Finally, the results showed that a HO to a 30GHZ IRS-assisted link with 64 ULA antenna elements and 1000 IRS elements will perform comparably to the LOS signal strength.