Evaluation and Optimization of LTE-V2X Mode 4 under Aperiodic Messages of Variable Size

Abstract: Vehicular networks connect vehicles for improved road safety and efficiency with the assistance of wireless information exchange. Vehicular networks are based on the frequent broadcast of awareness messages referred to as CAM (Cooperative Awareness Messages) or BSM (Basic Safety Message) in the ETSI and SAE standards, respectively. Vehicular network technology mostly used nowadays is based on cellular networks (LTE-V2X, 5G NR-V2X). LTE-V2X is an evolution of the 3GPP standard for 4G/LTE that allows vehicles to exchange information with other vehicles, pedestrians, or fixed objects such as traffic lights in their surroundings without the requirement of any infrastructure support. Reliable transmission of this information is important in LTE-V2X technology to confirm safety on the roads and effectively manage traffic flow. Most of the available studies are based on simplified data traffic models that generate CAMs at periodic intervals and with a fixed message size. In reality, the size and interval between the messages are not fixed and different from the simplified model. There are a few studies based on the real CAM generation (also known as the Empirical CAM Model) that show the significant deviations in results found with an unrealistic simplified traffic model. The Empirical CAM Model generates aperiodic messages of various sizes which leads to certain inefficiencies that affect the performance of LTE-V2X. In this thesis, those inefficiencies due to the realistic CAM generation are addressed and some mechanisms are also proposed and analyzed to overcome those effects. The results obtained in this thesis could be used not only for a better configuration of LTE-V2X but also for future standardization of its evolution.