## 1 Introduction  
As the demand for ubiquitous connectivity and high capacity increases [1], traditional radio frequency (RF) wireless communications technologies are plagued by spectrum deficiency and high energy-consumption issues. As an alternative, visible light communication (VLC) opens up a new frontier for sixth-generation (6G) communication thanks to its superior large, cost-free optical spectrum and energy efficiency [2; 3]. Along with this, the widespread adoption of LED lighting infrastructure and camera-equipped smart devices further motivates the usage of VLC. Particularly, optical camera communication (OCC), as a practical VLC technology that can reuse high-efficiency LEDs and camera-equipped smartphones for data communication, has attracted extensive attention from academic and industrial communities [4; 5; 6; 7]. Compared with traditional RF wireless communication technologies, OCC has the advantages of non-licensed channels, no electromagnetic interference radiation and low power consumption [8; 9; 10], which can be used in the fields of indoor wireless communication [11; 12], indoor precise positioning [13; 14], underwater environments [15] and intelligent transportation [16; 17]. Optical camera communication systems built on commercial off-the-shelf (COTS) equipment typically employ LED lighting infrastructure as transmitters and low-cost cameras as receivers. However, limited by the inherent conditions of low frame rate (typically limited to 30/60 frames per second (fps)) and the low sampling rate of ordinary cameras,the early works of OCC can only reach a data rate of several bytes per second [18; 19]. To overcome this limitation, Prof. [PERSON]'s team [4] proposed using the rolling shutter effect of complementary metal oxide semiconductor (CMOS) cameras to sample ON-OFF Keying (OOK) modulation signals, which can significantly increase the communication data rate to the kbps level [20; 21; 22]. During rolling shutter operation, instead of exposing the entire image frame at once, the camera conducts exposures in a column-by-column (or row-by-row) manner, forming bright or dark stripes in the received image illustrating the \"ON\" or \"OFF\" status of the LED transmitters [20; 23]. In general, the camera first searches for the region of bright and dark stripes concentration from the received image; that is, the Region of Interest (RoI), and then extracts a single row (column) pixel from the RoI to form a grayscale vector for demodulation and decoding of optical signals. However, the existing OCC systems still have problems such as small communication capacity, which need to be resolved. Aiming at addressing the problem of the small communication capacity of OCC, several methods have been proposed in prior works. [PERSON] and [PERSON] et al. [24; 25] systematically analyzed and revealed the optical communication reception capability of ordinary cameras from the theoretical and experimental levels, and focused on analyzing system communication capabilities using Frequency Shift Keying (FSK) modulation. [PERSON] et al. [26] of Huawei proposed a series of undersampling modulation schemes, such as Undersampling Phase Shift ON-OFF Keying Modulation (UPSOOKM [27]), Undersampling Pulse Amplitude Modulation (UPAM [28]), to realize a flicker-free OCC system with higher spectral efficiency. However, due to the low frame rate of ordinary cameras and the low response frequency of ordinary LED luminaires, the rate of existing OCC systems based on low-order modulation is still meager. To this end, the researchers tried to improve the communication capacity of the OCC system by designing new modulation methods that support higher orders or using the multi-lamp collaborative transmission. Since the camera can usually distinguish the color of the light, [PERSON] et al. [29] used RGB LED lamps to realize high-order Color Shift Keying (CSK) modulation, which improved the communication capacity of OCC. In order to support the compatibility of communication and lighting, [PERSON] et al.