Optical camera communication (OCC), as a complementary technology of radio frequency (RF), has played an important role in alleviating the burden on the existing spectrum and enhancing the reliability of communication. Theoretical investigations which describe the unique characteristics of camera-based optical wireless communication systems on a complete system model are limited, as most existing research utilized the indicators that are applied in photo detector (PD)-based systems. Due to the fact that cameras use pixel values to record the intensity of the LED, which carries the signals information, analysis based on pixel values has the ability to intuitively reflect OCC systems features. Motivated by this, a comprehensive system model which considers the photoelectric conversion and the imaging process of the camera is presented to characterize OCC systems in this paper. The proposed model which has been validated on the hardware platform describes the relationship between the LED driving current and the final pixel values on the image sensor. Some system parameters’ impact has been analyzed based on the proposed system model and corresponding experimental results. Performance analysis has been provided to characterize OCC systems from the communication perspective. Our investigation may help introduce a new perspective to understand the principle of OCC, as well as providing the theoretical support needed for the design in practical systems.

In the Vehicle to Vehicle (V2V) communication based on Optical Camera Communication (OCC), optical signals are transmitted using LED arrays and received employing cameras. In a complex scene, how to accurately detect and recognize LEDs in real time remains a problem. To solve this problem, this paper designs an end-to-end network based on You Only Look Once version 5 (YOLOv5) object detection model, which can precisely detect the LED array position in real time and alleviate motion blur simultaneously. Further, we propose an LED segmentation recognition method, which is beneficial to more reliable LED status recognition. It allows more light sources to be used for communication, which can effectively improve data rate in the vehicle OCC system. The effectiveness of our method is demonstrated by theoretical analysis and experiments in real traffic scenes. Our code is available at https://github.com/cq100/D2Net.

The rapid development of the Internet of Things (IoT) has put great challenges on the next generation's communication technologies. Optical Camera Communication (OCC), with its advantages of the green principle, less electromagnetic interference, and harmonious integrations, can serve as a complementary, and sometimes viable alternative technology to mainstream Radio Frequency (RF)-based one. Designing efficient OCC platforms crucially involves accurate modelling of the OCC system and evaluating the efficiency of OCC-based techniques, which then stimulates related practical applications. This paper aims to provide a systematic perspective to understand OCC and to present design guidelines for OCC systems from theory to practice. First, the main parameters and analytical models for OCC basic components are presented to provide guidance on hardware parameter selection and system simulations. Next, typical implementation procedures and common performance evaluation criteria for an overall OCC system are provided. Then, detailed goal-oriented OCC enhancement solutions are summarized aiming to provide systematic guidelines for system performance enhancement. Finally, OCC designed examples are presented based on the results of our OCC experimental platform and some future research directions are discussed.

In this letter, a two-way full-duplex (FD) relay mixed radio frequency/free space optical (RF/FSO) system corrupted by self-interference is proposed and investigated. The RF/FSO channels employ Nakagami-m distribution and pointing errors combined Gamma-Gamma turbulence model, respectively. Relay selection strategies based on channel state information (CSI) are applied. Considering the effect of self-interference, the exact outage probability (OP) and upper bound achievable sum-rate (ASR) are presented and evaluated. To make the research more comprehensive, the analysis further covers the effect of residual self-interference on the considered system as well as compares the performance difference of FD relay and half-duplex (HD) relay. To get more insight, asymptotic OP is further presented. Results show that self-interference seriously constrains the system performance and applying self-interference cancellation (SIC) technology is quite necessary for FD relay system.

The overwhelming data rates in next generation wireless networks impose a burden on the high-capacity network planning. One promising strategy to meet the demand for high-capacity communications is to augment radio frequency (RF) based multi-channel multi-radio (MCMR) wireless mesh network (WMN) by free-space optics (FSO). In this paper, we construct a hybrid RF/FSO MCMR WMN topology and address its resource allocation (RA) problem in terms of interface assignment, channel allocation, routing, FSO link allocation, and topology control. Considering the weather effects on FSO link availability and the fading nature of RF links, the RA problem is formulated as a two-stage optimization problem with the objective of maximizing the network throughput. In our optimization model, we formulate each stage as a mixed integer linear program, and the bottleneck RF links are gradually upgraded by FSO links. To avoid the computational complexity of the second stage optimization, an improved iterated local search algorithm is proposed. Simulation results show that our RA scheme is efficient and the throughput can be enhanced dramatically by proper FSO link augmentation.

In this paper, the performance of a two-way mixed radio frequency/free space optical (RF/FSO) relaying system in the presence of co-channel interference (CCI) is investigated. The RF links are modeled as Nakagami-m distribution, and FSO links adopt Gamma-Gamma turbulence model. To improve spectral efficiency (SE), relay exchanges the information between two terminals in three phases via RF and FSO links. Meanwhile, CCIs are considered at both relay and destination. Novel closed-form upper bounds expressions for signal to interference plus noise ratios (SINRs) are derived, based on that lower bounds outage probability (OP), average bit error rate (BER) and outage capacity are further presented for both RF/FSO and FSO/RF links. Then, asymptotic expressions are provided to predict the diversity order. Additionally, the effect of various parameters on system performance, such as interference numbers and power, are investigated and compared including interference-free condition. Simulation results show that, in interference-effected system, when average signal-to-noise ratio (SNR) increases, system performance enhances first and then remains unchanged. This phenomenon does not occur in interference-free system, which implies the system performance is limited by the numbers and power of CCIs. Moreover, the effect of pointing errors on system performance is further investigated.