11 research outputs found
Downlink and Uplink Intelligent Reflecting Surface Aided Networks: NOMA and OMA
Intelligent reflecting surfaces (IRSs) are envisioned to provide
reconfigurable wireless environments for future communication networks. In this
paper, both downlink and uplink IRS-aided non-orthogonal multiple access (NOMA)
and orthogonal multiple access (OMA) networks are studied, in which an IRS is
deployed to enhance the coverage by assisting a cell-edge user device (UD) to
communicate with the base station (BS). To characterize system performance, new
channel statistics of the BS-IRS-UD link with Nakagami- fading are
investigated. For each scenario, the closed-form expressions for the outage
probability and ergodic rate are derived. To gain further insight, the
diversity order and high signal-to-noise ratio (SNR) slope for each scenario
are obtained according to asymptotic approximations in the high-SNR regime. It
is demonstrated that the diversity order is affected by the number of IRS
reflecting elements and Nakagami fading parameters, but the high-SNR slope is
not related to these parameters. Simulation results validate our analysis and
reveal the superiority of the IRS over the full-duplex decode-and-forward
relay.Comment: Accepted for publication in the IEEE Transactions on Wireless
Communication
On the IRS Deployment in Smart Factories Considering Blockage Effects: Collocated or Distributed?
In this article, we study the collocated and distributed deployment of
intelligent reflecting surfaces (IRS) for a fixed total number of IRS elements
to support enhanced mobile broadband (eMBB) and ultra-reliable low-latency
communication (URLLC) services inside a factory. We build a channel model that
incorporates the line-of-sight (LOS) probability and power loss of each
transmission path, and propose three metrics, namely, the expected received
signal-to-noise ratio (SNR), expected finite-blocklength (FB) capacity, and
expected outage probability, where the expectation is taken over the
probability distributions of interior blockages and channel fading. The
expected received SNR and expected FB capacity for extremely high blockage
densities are derived in closed-form as functions of the amount and height of
IRSs and the density, size, and penetration loss of blockages, which are
verified by Monte Carlo simulations. Results show that deploying IRSs
vertically higher leads to higher expected received SNR and expected FB
capacity. By analysing the average/minimum/maximum of the three metrics versus
the number of IRSs, we find that for high blockage densities, both eMBB and
URLLC services benefit from distributed deployment; and for low blockage
densities, URLLC services benefit from distributed deployment while eMBB
services see limited difference between collocated and distributed deployment