## 5 Conclusions  
In this paper, for the OCC technique, we adopt an 8 \(\times\) 8 LED array for data transmission to the OCC system. This 2D OOK-MIMO modulation scheme-based system is designed for IoT applications and supports the rotation effect using a special spatial frame format of the LED matrix. Specifically, we collect and transmit measurement data from the environment, such as temperature and humidity, utilizing an LED array based on 2D code. To control data decoding and the frame rate variation effect, the SN is used to control the order of data packets in multiple consecutive images and thus avoid missing data. We also evaluated the relationship among the communication distance, SNR value, and exposure time by measuring the SNR at several communication distances and with different exposure time values. The results show that the SNR rises with the exposure time, while the system bandwidth correspondingly falls. Therefore, choosing the exposure time needs to be carefully considered when deploying the system. Moreover, OCC performance can be improved with the YOLOv8 algorithm instead of the RoI algorithm considering the mobility environment. In addition, the deep-learning decoder also showed higher performance compared to the conventional algorithm. This was revealed by the BER performance  
\begin{table}
\begin{tabular}{c c c} \hline \hline \multicolumn{3}{c}{**Transmitter Side**} \\ \hline LED array size & 8 \(\times\) 8 & 16 \(\times\) 16 \\ \hline The number of LEDs & 64 & 256 \\ \hline Power supply & 5 V, 2 W & 5 V, 5 W \\ \hline FEC & Hamming (11/15) & \\ \hline Packet rate & 60 packet/s & \\ \hline  & Receiver side & \\ \hline Camera & Point Grey rolling-shutter camera & \\ \hline  & Throughput & \\ \hline Uncode bit rate & 3.840 kbps & 15.360 kbps \\ \hline Code bit rate & 2.816 kbps & 11.264 kbps \\ \hline \hline \end{tabular}
\end{table}
Table 1: Characteristic parameters of the proposed scheme.  
Figure 10: BER performance of proposed system for an 8 \(\times\) 8 LED array with different distances considering a velocity of 3 m/s with exposure time of 100 μs.  
of the 2D-MIMO scheme considering different distances (2-22 m) and a mobility of 3 m/s with a BER of \(10^{-4}\) at a distance of 7 m.  
The following are available online at [[https://www.mdpi.com/article/10.3390/app14031003/s1](https://www.mdpi.com/article/10.3390/app14031003/s1)]([https://www.mdpi.com/article/10.3390/app14031003/s1](https://www.mdpi.com/article/10.3390/app14031003/s1)). The supplementary material video shows the implementation of our proposed scheme at a distance of 2 m.  
All authors contributed to this paper: [PERSON] proposed the idea and implemented the methodology; [PERSON] and H.N. reviewed the work and edited the paper; [PERSON] performed all experiments; [PERSON] supervised the work and provided funding support. All authors have read and agreed to the published version of the manuscript.  
This research was supported by the Ministry of Science and ICT (MSIT), Korea, under the Information Technology Research Center (ITRC) support program (IITP-2018-0-01396) supervised by the Institute for Information and Communications Technology Promotion (IITP); this work was also supported by a National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT) (No. 2022R1A2C1007884).  
Not applicable.  
The data presented in this study are available on request from the corresponding author. The data are not publicly available due to project requirements.  
The authors declare no conflicts of interest.