Title: Throughput enhancement of RIS and STARRIS using adaptive modulation and coding for 6G systems

Authors: Nadhir Ben Halima; Sajid Mubashir Sheikh

Addresses: Department of Information Technology, Community College of Qatar, Doha 7344, Qatar ' Department of Electrical Engineering, University of Botswana, Private Bag UB 0061, Gaborone, Botswana

Abstract: In this article, the throughput of reconfigurable intelligent surfaces (RIS) is improved using adaptive modulation and coding (AMC). The best modulation and coding scheme (MCS) is selected at the transmitter using the instantaneous signal to noise ratio (SNR) measured at the receiver and sent back on the feedback channel. RIS is placed between the transmitter and the receiver so that the SNR is maximised at the receiver side as RIS reflections are combined coherently at the receiver and results in significant spatial diversity. All reflections on RIS have a zero phase at the receiver. We show that RIS using AMC offers a larger throughput than conventional RIS with fixed MCS for all SNR range. RIS with AMC offers 48, 42, 36, 30, 24, 18 dB gain for N = 256, 128, 64, 32, 16, 8 reflectors. We obtained 10 dB gain when RIS uses AMC versus 256-QAM. We also improve the throughput of Simultaneously Transmitting And Reflecting RIS (STARRIS) using AMC. We obtained 13 dB gain when STARRIS uses AMC versus 256-QAM.

Keywords: adaptive modulation and coding; AMC; reconfigurable intelligent surfaces; RIS; modulation and coding scheme; MCS; throughput enhancement; 6G.

DOI: 10.1504/IJAHUC.2024.140438

International Journal of Ad Hoc and Ubiquitous Computing, 2024 Vol.46 No.4, pp.195 - 202

Received: 07 Feb 2024
Accepted: 17 Apr 2024
Published online: 09 Aug 2024 *

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