## 1 Introduction
Building on the research found in [27], which combined M-MIMO, mmWave, and RIS to enhance wireless communication at frequencies of 28 GHz and 73 GHz, this study explores the effects of increasing the size of the RIS array. The initial findings highlighted how M-MIMO can manage multiple data streams concurrently, how mmWave technology benefits from high-frequency capabilities, and the role of RIS in improving signal dissemination. This combination led to better coverage, minimized interference, and enhanced EE, providing important insights for advancing B5G. The current research will investigate the impact of adding more RIS elements on system performance. Many traditional studies on mmWave communication emphasize channel coefficients that may not accurately reflect the true characteristics of mmWave channels. In this research, we utilized the SimRIS channel simulator to generate realistic channel coefficients tailored for both indoor and outdoor settings. As a result, we achieved the desired ABER by employing higher signal-to-noise ratio (SNR) values. Additionally, this performance can be improved by increasing the RIS array size. This study primarily focuses on this aspect. The proposed work's contributions are as follows:  
* This study thoroughly analyzes ABER and sum rate performance in RIS-assisted mmWave M-MIMO systems utilizing standardized 5G channel models defined by 3 GPP. It serves as a practical benchmark for performance evaluation. * A comprehensive comparison between indoor (InH-Office) and outdoor (UMi-Street Canyon) settings at frequencies of 28 GHz and 73 GHz, demonstrating that the 28 GHz band yields better ABER performance in indoor environments. * Furthermore, this research evaluates continuous phase RIS against discrete phase configurations (1-bit and 2-bit), emphasizing the performance trade-offs and quantization effects crucial for real-world implementations. * This study also highlights critical aspects overlooked in previous research, such as performance in multi-user scenarios and the effects of increasing RIS elements. The findings reveal that a higher RIS array size can significantly improve ABER performance. The upcoming sections of this paper are ordered as follows: Section 2 covers recent works in the literature related to M-MIMO, mmWave M-MIMO, RIS, and RIS integrated with mmWave M-MIMO. The system model for RIS-assisted mmWave M-MIMO is presented in Section 3. Section 4 describes corresponding 5G channel models for indoor and outdoor scenarios. The outcomes from the Monte Carlo simulation, demonstrating the ABER performance of RIS-assisted mmWave M-MIMO, are exemplified in Section 5. Section 6 concludes this study and emphasizes potential directions for future research. \begin{table}
\begin{tabular}{l c c c c c} \hline \hline
**Components/Works** & [25] & [26] & [27] & [28] & **Proposed** \\ \hline mmWave channel modeling framework & ✓ & ✓ & ✓ & ✓ & ✓ \\ \hline
3 GPP-based RIS simulation & ✓ & ✓ & ✓ & ✓ & ✓ \\ \hline Discrete vs. continuous phase RIS analysis & ✓ & ✗ & ✗ & ✗ & ✓ \\ \hline Quantified ABER impact for indoor/outdoor scenarios (28/73 GHz) & ✗ & ✗ & ✓ & ✗ & ✓ \\ \hline Analysis on impact of increasing \(N\) and \(N_{t}\) & ✗ & ✗ & ✓ & ✓ & ✓ \\ \hline Analysis on impact of size of RIS array & ✓ & ✗ & ✗ & ✓ & ✓ \\ \hline Multi-user scenarios & ✗ & ✗ & ✗ & ✗ & ✓ \\ \hline Sum rate analysis & ✓ & ✓ & ✗ & ✓ & ✓ \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Proposed framework vs. Existing SimRIS implementations.