Improving the Performance of Vehicular Communication in NOMA Systems using Cooperative Transmission

Abstract

The vehicular network is one of the most promising technologies for intelligent transportation system (ITS). And intelligent transportation system has been attracting much attention because of the various applications for vehicles, passengers, and pedestrians. The key technologies in ITS, vehicle-to-infrastructure (V2I) or vehicle to vehicle (V2V) communications, involves the networking of vehicles and other communication devices like the RSU (Roadside Unit) and OBU (On Board Unit). So, a secure and efficient Vehicle-to-Vehicle (V2V) and Vehicle-to Infrastructure communications are the key to support road safety and traffic efficiency applications in ITS. The services and applications in vehicular communication can mainly be classified into two types. Safety services are the first which require an extremely low latency, such as the vehicle collision warning, obstacle detection and driving assistances. The other is the infotainment services which prefer link reliability to the latency, such as file transmissions, social entertainments, and online services. Vehicular communications offer several applications regarding accident prevention, such as sending safety messages that alert vehicles about accidents happening in their surroundings. However these applications require high bandwidth and high spectral efficiency to insure high reliability and low latency communications. Due to this reason different researchers have been proposed conventional OMA, non-cooperative NOMA and cooperative NOMA multiple access schemes to optimize resource utilization and reduce interference. In this thesis, cooperative NOMA is proposed to improve the performance of vehicular communication. The performances of Conventional OMA, Non-cooperative NOMA and Proposed Cooperative NOMA are analyzed using the performance metrics namely: Bit Error Rate, Outage Probability, and Average Achievable Rate for different M-QAM modulation order namely: 4-QAM, 16-QAM, 64-QAM, 128-QAM, and 256-QAM over Nakagami and Rayleigh fading channel model. Simulation result shows that the performance of proposed Cooperative NOMA systems outperforms over Conventional OMA and Non-cooperative NOMA in Bit Error Rate, Outage Probability, and Average Achievable Rate analysis. The proposed cooperative NOMA system resulted with 96% performance improvement compared to non cooperative NOMA system as observed from SNR versus outage probability analysis.