Araç görünür ışık haberleşmesinin performans değerlendirmesi ve deneysel doğrulaması

Vehicular development relays heavily on data communications for supporting some of the future applications. Vehicle platoon and Autonomous Vehicles (AVs) are some of the applications that will be commercially available in this decade. From that point, Intelligent Transportation System (ITS) become one of the most attractive fields for the applications of wireless communications where Decentralized Environmental Notification Messages (DENM), Co-Operative Awareness Massages (CAM) or any application specific massages could be exchanged among vehicles. Those massages could be further utilized by traffic management which will participate in reducing both trip time and environmental pollution. This motivates automotive manufacturers to rely on vehicular connectivity to catch up with the market development through technology implementation. In ITS applications, a highly reliable, high data rate and low latency communication link is required. Dedicated Short-Range Communication (DSRC) and Cellular vehicle-to-everything (CV2X) are the conventional Radio Frequency (RF) technology for ITS applications. Due to the bandwidth limitation of the available RF spectrum and Electromagnetic Interference (EMI) issues, Visible Light Communication (VLC) has emerged as powerful wireless access technology by offering a large license-free bandwidth and immunity to EMI. VLC is a possible candidate for Vehicle-to-Vehicle (V2V), Vehicle-to-Infrastructure (V2I) as well as Vehicle-to-Pedestrian (V2P) applications. Particularly, VLC has a robust performance in user-dense environments and is considered as a complementary technology. Automotive manufacturer recently increases the adoption of Light-Emitting-Diodes (LEDs) in the vehicle's bodies. Since VLC allows the dual use of LED for illumination and communication purposes, this allows VLC to be considered as a complementary approach for vehicular connectivity. VLC system modulates the intensity of the light source by superimposing the desired information signal upon the driving Direct Current (DC). The DC value is selected according to the desired operating point taking into account the amplitude constraints. Since the frequency of the modulating signal is very high, the flickering of the light intensity cannot be observed by the human eye. Typical modulation choice for VLC systems is On-Off Keying (OOK) and pulse modulation techniques while other modulation techniques such as Orthogonal Frequency Division Multiplexing (OFDM) have been further proposed to support ultra-high-speeds on the order of Gbps. There are some concerns for practically implementing the Vehicle-to-Everything (V2X) VLC applications. For instance, the practical implementation aspects. Despite the shortage in the commercially available products for vehicular VLC, the frontend has to be designed and its effect should be considered in the system implementation. Moreover, the effect of the outdoor environment, such as sun light, has to be characterized for accurate system design. In addition, the as in any communication system, channel modeling plays a critical role in vehicular VLC systems, especially with the asymmetrical pattern of vehicular light source, it needs to be experimentally modelled. Another critical aspect is the effect of mobility and the location of the photodetector on the vehicle must be properly defined for having a robust vehicular VLC link in different road shapes (i.e., straight and curved roads). As a benchmark, the performance of vehicular VLC should be further compared with RF. Motivated by these, we firstly investigate the baseband processing and the experimental implementation of different modulation techniques for VLC systems. After that, we design frontend that support high power transmission of vehicular LEDs and investigate its experimental effects on the system performance. We then characterize the impairments of the outdoor environment and identify the proper choice of the lens combination that suites the vehicular environment. Another critical aspect for vehicular VLC system is channel model is further considered through experimentally modelling the pathloss of the vehicular asymmetrical light source. This model is further extended to be used for special case (truck-to-truck VLC system) of truck's vertical oscillation. Counting on these, we investigate the critical aspect of the vehicular VLC link performance in the presence of mobility for passenger vehicles as well as for heavy vehicle (i.e., Truck). For benchmarking purposes, we further implement a hybrid system (VLC/RF) for comparison purposes as well as deploy a switching algorithm to satisfy a specific Quality of Service (QoS).