# Farm Monitoring System with Drones and Optical Camera Communication
## 2 Related Work
### Optical Camera Communication (OCC)  
OCC is a technology that utilizes a camera and a light source for data transmission. Light sources such as LED panels, displays, and digital signage are used as transmitters to send digital data in the form of optical signals [27]. A receiver camera captures the transmitted signals using a complementary metal-oxide-semiconductor (CMOS) sensor. OCC is particularly suited for point-to-multipoint (P2 MP) communication, as it can use multiple light sources in a given area with minimal interference between transmitters. The multiple light signals captured in the image can be demodulated by cropping the pixels corresponding to each light source [28]. OCC falls under the category of visible light communication (VLC), where a light source serves as the transmitter and a camera functions as the receiver.  
The primary advantages of OCC include cost efficiency, unlicensed operation, and low power consumption. Since most modern agricultural drones are equipped with cameras [8], they can serve as effective receivers. This makes OCC a promising technology for remote sensing applications in agriculture. In [29], the performance of OCC was evaluated based on parameters such as camera sampling rate, exposure time, focal length, pixel edge length, transmitter configurations, and optical flicker rate. The study defined the signal-to-interference-plus-noise ratio (SINR) and analyzed different modulation schemes. Ambient light interference is a major challenge for visible light communication, including OCC. Some studies have proposed solutions to mitigate this issue. [PERSON] et al. [30] examined the impact of sunlight on VLC. They clarified the specific effects of sunlight and proposed a system to counteract them, achieving data rates exceeding 1 Gb/s even under strong sunlight. [PERSON] et al. [31] developed a vehicle-to-vehicle communication system using OCC. They achieved a reception rate of 13.0 frames per second (fps) under real-world driving and outdoor lighting conditions. [PERSON] et al. [32] conducted experiments evaluating a 400-m communication link using OCC in outdoor environments. Their results demonstrated stable communication performance under various weather and lighting conditions. Drone-based OCC systems have also been studied in various applications. [PERSON] et al. [33] investigated OCC systems using drones equipped with RGB-LEDs and a high-speed camera to achieve communication over a distance of 300 meters. Their experimental results demonstrated that efficient and accurate communication is possible by employing object detection techniques. [PERSON] et al. [34] focused on the trajectory control of drones to maintain line-of-sight (LoS) communication links in OCC systems. They proposed a distributed trajectory control algorithm that allows drones to avoid inter-light interference during communication. However, the previous studies did not consider dense sensor data collection in agriculture using drones and OCC.  
Furthermore, to the best of our knowledge, there has been no previous work on drone-based agricultural sensor networks using OCC. This paper proposes a novel system that combines drones and OCC for high-density sensor data collection in agriculture. The proposed system leverages the advantages of OCC to enable efficient data transmission from sensor nodes to a drone-mounted camera. The system is designed to be cost-effective, scalable, and suitable for deployment in areas with limited infrastructure. The details of the proposed system are presented in the following section.