Large Intelligent Surfaces With Discrete Set of Phase-Shifts Communicating Through Double-Rayleigh Fading Channels

Abstract

It is known that the Central Limit Theorem (CLT) is not always the most appropriate tool for deriving closed-form expressions. We evaluate a Single-Input Single-Output (SISO) system performance in which the Large Intelligent Surface (LIS) acts as a scatterer. The direct link between the transmitting and receiving devices is negligible. Quantization phase errors are considered since the high precision configuration of the reflection phases is not always feasible. We derive exact closed-form expressions for the spectral efficiencies, outage probabilities, and average symbol error rate (SER) of different modulations. We assume a more comprehensive scenario in which $b$ bits are dedicated to the LIS elements' phase adjustment. From Monte Carlo simulations, we prove the excellent accuracy of our approach and investigate the behavior of power scaling law and power required to reach a specific capacity, depending on the number of reflecting elements. We show that the LIS with approximately fifty elements and four dedicated bits for phase quantization outperforms the conventional system performance without LIS.

Outage Probability Analysis of RIS-Assisted Wireless Networks With Von Mises Phase Errors

“…In this section, we analyze the error of the proposed approximation and prove that pR (r) and FR (r) given in (15) and ( 16) are asymptotically precise in N for the lower tail of the distribution of R. The approximation errors arise from the higher order terms of the Taylor series of ρJ 0 (ρr) and ln (J 0 (ρ)):…”

“…Furthermore, it is shown in [13] that the CLT gives a poor approximation for the outage probability or bit error rate (BER) at high SNR regime. To circumvent these issues, the authors of [14], [15] use the moment matching method to approximate the distribution of the fading coefficient corresponding to each reflected path by a gamma distribution. Although the approaches based on the gamma distribution are accurate to some extent, they do not provide bounds or asymptotically exact results for the outage probability.…”

Average Rate and Error Probability Analysis in Short Packet Communications Over RIS-Aided URLLC Systems

“…The best case and worst case channel characteristics are formulated as a Gamma RV with separate shape and rate parameters for each case in [26]. In [27] the absolute value of the reflected channel is considered as a Gamma RV then, the ergodic rate and outage probability analysis is investigated in terms of total RIS elements and having discrete phase shifts. Note that the analysis is performed over infinite blocklength regime without the presence of the direct channel.…”

“…Finally, by replacing ( 30) and ( 33) in ( 16) the approximate result will be obtained. Note that since C 1 is lower bounded byC 1 and C 2 ≤C 2 the achievable rate will attain its lower bound because of negative sign in C 2 in (27). ∎…”

Impact of IQ Imbalance on RIS-Assisted SISO Communication Systems

“…The direct signal path between the source and the destination is ignored in the rest of the paper [4], and the RIS is deployed to relay the scattered signal. Indeed, this assumption holds in the case of unfavorable propagation conditions that might be caused by an obstacle or a long distance, for example, [26][27][28].…”