# Transmit and Receive Diversity in MIMO Quantum Communication for High-Fidelity Video Transmission
## 4 Results and Discussion  
This study evaluates the performance of a superposition-based quantum communication system for video transmission in three diversity configurations: \(1\times 1\)SISO, \(2\times 1\)MISO, and \(1\times 2\)SIMO. Instead of varying GOP sizes, the evaluation is based on three representative video sequences selected for their differing levels of structural information (SI) and temporal information (TI), corresponding to high-motion, medium-motion, and low-motion characteristics. High-motion video [49] is characterized by rapid object movement and frequent scene transitions, resulting in high SI and TI values. This makes compression and transmission particularly challenging. The medium-motion video [50] exhibits moderate changes in scene and movement, leading to balanced SI and TI levels, and representing an average complexity case. In contrast, low-motion video [51] features relatively static scenes with minimal movement, producing moderate SI but low TI, making it the easiest to compress and transmit. Due to the use of three distinct video sequences, the final performance metrics are reported as the average values across all three types. This approach ensures a comprehensive evaluation of the effectiveness of the system under various content conditions. As shown in Figure 3, the PSNR, SSIM, and VMAF values of the decoded videos are plotted against the channel SNR for a GOP size of 8, a resolution of 320 \(\times\) 180, and a frame rate of 50 fps. The results indicate that the quantum system (Q) consistently achieves superior video quality, measured by PSNR, SSIM, and VMAF, compared to the classical system (C), particularly under low-SNR conditions across all diversity configurations, including MISO, SIMO, and SISO. The quantum system demonstrates that increasing channel noise results in more frequent quantum state errors during transmission. These errors are subsequently converted into classical bit errors during decoding, causing visible distortions and reducing the perceptual quality of the reconstructed video. In addition, both the MISO (transmit diversity) and SIMO (receive diversity) configurations outperform the SISO (no diversity) scheme in terms of video transmission quality in both quantum and classical systems. This advantage is most evident in the \(2\times 1\)MISO and \(1\times 2\)SIMO quantum setups, where the quantum system maintains strong video quality, as in PSNR results at SNR levels as low as 7 dB. In contrast, the \(1\times 1\)SISO configuration requires a minimum of 10 dB SNR to achieve comparable performance. This performance gap underscores the benefit of using diversity techniques in conjunction with quantum encoding to enhance communication robustness. The improved resilience to noise enables more accurate video reconstruction even in challenging channel conditions. A similar trend is observed in the SSIM and VMAF results, further confirming the superior perceptual and structural quality delivered by the quantum-enhanced transmission framework across all diversity schemes. It is also observed that the \(2\times 1\)MISO setup exhibits around a 3 dB performance drop relative to the \(1\times 2\)SIMO scheme in both the classical and quantum cases. This reduction is due to the experiments being configured with equal total transmission power across all configurations, which inherently benefits receive diversity. As illustrated in Figure 4, the PSNR, SSIM, and VMAF results for a GOP size of 16 follow a similar trend to those observed with a GOP size of 8. In all diversity configurations, including MISO, SIMO, and SISO, the quantum system continues to outperform the classical system. Additionally, both transmit (\(2\times 1\)MISO) and receive diversity (\(1\times 2\)SIMO) provide better results compared to the no diversity (\(1\times 1\)SISO) scheme. However, a no ticeable drop in overall performance is observed when the GOP size increases from 8 to 16. To further investigate this behavior, Figure 5 presents the results for a GOP size of 32.