## 4 Conclusions  
The proposed quad-port MIMO antenna, enhanced by a 3\(\times\)3 MTM superstrate, achieves a 300 MHz bandwidth (3.5-3.8 GHz), high gain (4.5-5 dBi), and excellent isolation (\(<\)\(-\)30 dB), meeting ORAN's multi-operator requirements. Real-world testing confirms stable 200 Mbps downlink and 70 Mbps uplink throughputs, with acceptable latency increases (25-30 ms) offset by reduced jitter, making it ideal for indoor 5G deployments. It is specifically designed for a shared infrastructure of ORAN-compliant software-defined radio implementations targeting indoor sub-6 GHz 5G deployments. The configuration aims for a suitable bandwidth for multi-operator, high-gain, and improved port isolation. The basic design features an inset-feed rectangular patch with four additional slits, a centered slot to enhance bandwidth by more than 300 MHz (3.5-3.8 GHz), and a 3 \(\times\) 3 metamaterial superstrate layer at a height of \(\sim\)0.002\(\lambda\)0. The presented design, with the addition of the MTM superstrate, achieves improved port isolation from greater than \(-\)30 dB to less than \(-\)30 dB for any adjacent ports, and a gain enhancement from 1.2 dB to 4.5 dB. Furthermore, during real-time proof-of-concept testing, throughputs increase by almost 20 Mbps and maintain  
Figure 13: Walk test coverage analysis of the proposed MIMO antenna. \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Ref**} & \multirow{2}{*}{**Array**} & \multicolumn{2}{c}{\(\mathbf{F_{c}}\)} & \multicolumn{2}{c}{**Antenna**} & \multirow{2}{*}{**Material**} & \multirow{2}{*}{\(\eta\) \%} & \multicolumn{2}{c}{**PG**} & \multicolumn{2}{c}{**PI**} & \multirow{2}{*}{**Technique**} & \multirow{2}{*}{**ECC**} & \multirow{2}{*}{**RWP**} \\  & & (GHz) & & & & & dBi & & & & \\ \hline
[12] & 4 \(\times\) 2 & 4.2 & 150 \(\times\) 75 \(\times\) 1.6 & FR4 & 90 & 4 & 21 & Neutralization Line & 0.017 & No \\
[14] & 4 \(\times\) 2 & 4.7 & 60 \(\times\) 30 \(\times\) 2 & FR4 & 48 & 2.5 & 12.5 & Ground Shortening Pins & 0.14 & No \\
[15] & 2 \(\times\) 2 & 4.5 & 50 \(\times\) 50 \(\times\) 12.5 & [PERSON] 5880 & 80 & 4.8 & 20 & Frequency Selective Surface & \textless{}0.1 & No \\
[16] & 2 \(\times\) 8 & 4.65 & 160 \(\times\) 68 \(\times\) 0.8 & FR4 & 68 & N/G & 15 & & Decoupled with & \textless{}0.04 & No \\
[17] & 1 \(\times\) 2 & 4.5 & 30.98 \(\times\) 4.2 & FR4 & 90 & 4.585 & 15 & & T-shaped Hemispherical & \textless{}0.001 & No \\
[18] & 3 \(\times\) 2 & 4.5 & 70 \(\times\) 70 \(\times\) 70 & Rogers 5880 & 80 & 4.3 & 21 & Slots and Parasitic & \textless{}0.004 & No \\ Pro & 2 \(\times\) 2 & 3.65 & 75 \(\times\) 75 \(\times\) 18.2 & FR-4 & 50 & 4.8 & 30 & Superstrate @ 0.22\(\lambda\)0 & 0.002 & Yes \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Performance Comparison of Proposed Antenna with Recently Reported Antennas. consistency even during peak working hours. The presented design's performance characteristics were validated through both numerical simulations and practical measurements. Additionally, thorough ORAN-compliant SDR testing confirms its suitability for indoor 5G wireless networks. Conceptualization, A.A.K. and Z.W. ; Formal analysis, D.L. and A.A. ([PERSON]); Funding acquisition, Z.W. and A.A. ([PERSON]); Investigation, A.A.K. and A.A. ([PERSON]); Methodology, A.A.K. ; Project administration, Z.W. and D.L. ; Resources, Z.W. and A.A. ([PERSON]); Software, A.A.K., D.L. and A.A. ([PERSON]); Supervision, Z.W. and A.A. ([PERSON]); Validation, Z.W., A.A. ([PERSON]) and A.A. ([PERSON]); Writing--original draft, A.A.K. and A.A. ([PERSON]); Writing--review and editing, Z.W. and A.A. ([PERSON]). All authors have read and agreed to the published version of the manuscript. This work is supported in part by the National Natural Science Foundation of China (No. 62431009), the National 2011 Collaborative Innovation Center of Wireless Communication Technologies (No. 2242022k60006), and the Research Project Fund of Songjiang Laboratory (No. SL20230104). Not applicable.