## 1 Introduction
In [10], the author presented the adverse effects of EMI on human health, especially on brain functions; this fact is now receiving the attention of health researchers worldwide. Recently, the visible light technique has risen as a novel EMI-free substitute for RF technology [11]. In a conventional VLC system, the photodiode receives data according to the fast switching on or switching off of information from LEDs on the transmitter side [12]. In [13], the author implemented an ultra-high-speed pulse density (PD) modulation scheme with extremely effective spectral properties based on the VLC technology. To transmit high-speed data, [14; 15] applied multiple-input multiple-output (MIMO) in the VLC/Li-Fi technology with ultra-high-speed multi-channels. When PD schemes are used as detectors, VLC and Li-Fi have a disadvantage that they can only be operated within short distances; this suits the indoor communication system. In an outdoor environment, the effect of the distortion channel impedes the photodiodes from receiving light intensities. To eliminate this, the OCC technology deploys an image sensor as a detector, which can receive data up to 200 m. In [16; 17], the researchers assumed that the type of an image sensor (global shutter or rolling shutter) affects the OCC performance. To satisfy [PERSON]'s law in the OCC system based on the global shutter camera, the sampling rate needs to focus on the frame rate of the camera. However, with a rolling shutter camera, the sampling rate needs to focus not only on the frame rate of the camera but also on the camera rolling rate. Then, the rolling shutter camera is usually operated for a high data rate system. For long-distance operations and to enhance the signal-to-noiseratio (SNR), the focal length was employed to focus the light beam on the image sensor. Currently, Li-Fi technology is being improved by using a photodiode lens to extend the communication distance, but the maximum distance is only 10 m [18]. The OCC system can easily deploy the MIMO technique. It can cope with the big OCC problem of simultaneous connection with many light sources, and it can make it feasible for the camera as well. The MIMO technique is not feasible for the PD-based system when connecting a large number of links. Besides, OCC technology can be operated with many applications based on the image processing algorithm. Region-of-interest (RoI) signaling is an algorithm, which has been applied in OCC [19]. Based on the rolling shutter effect and orthogonal frequency-division multiplexing (OFDM) waveform, the authors of [20] proposed a rolling-OFDM modulation for high-rate communication because when intensity modulation/direct detection (IM/DD) modulation is used, it is difficult to find suitable LED materials comparable with the on-off keying. A two-dimensional OFDM for OCC using the screen method has been discussed in [21]; the researchers achieved a high data rate. However, one disadvantage was the large transmitter size and the short distance, which made it an expensive transmitter. In [22], we proposed the camera on-off keying (COOK) scheme with a single LED. To decode data, we used the zero-crossing to verify the on/off value in the images. However, certain drawbacks were found. The limited transmission distance and high error rate were compared by using a matched filter to decode the data. In this paper, we propose the MIMO-COOK scheme in which the COOK scheme has been upgraded by using MIMO, region of interest, and matched filter. These technologies are also recommended in [23; 24] but we proposed this scheme to upgrade the conventional COOK, which is recommended in IEEE 802.15.7-2018 standard. With this upgrade scheme, the system performance, distance communication and data rate are improved compared with the conventional COOK, which will be illustrated below. The remainder of this paper consists of four sections. Section 2 highlights the contributions of the MIMO-COOK scheme. In Section 3, we show the system architecture of the proposed scheme.