RELATIVE POSITIONING FOR VEHICLE-TO-VEHICLE COMMUNICATION-ENABLED VEHICLE SAFETY APPLICATIONS

摘要

Use of wireless technology to enable communications between all road user entities is generally termed V2X or Vehicle-to-Entity connectivity. Use of V2X communications to make everyone aware of each other is seen as a promising approach to reduce the negative implications of road accidents and traffic congestion. According to USDOT statistics, roadway accidents are the leading cause of death for adults and roadway accidents also have a direct economic cost of over $ 200 billion per year. This is in addition to the time and resource loss associated with traffic congestion, resulting in a total estimated 4.2 billion lost hours per year.rnThe capability to estimate the position of a given entity with respect to another is a critical requirement in all V2X applications. Therefore, positioning and wireless communication capabilities can be considered the two critical building blocks of V2X. As the technology progresses, V2X-based awareness based advisory and warning applications may be extended to various levels of vehicle control, ranging from crash avoidance to fully automated driving. Global Navigation Satellite Systems (GNSS) is considered the most suitable core positioning technology for V2X. This implies strict accuracy, reliability and availability requirements for GNSS-based positioning.rnPrevious research and development efforts have looked at various methods of GNSS-based relative positioning for V2X applications. These efforts have confirmed that using simplified methods may not necessarily provide the robust operation needed in a real-life environment with different GNSS hardware, software, and other variability. GNSS based relative positioning techniques have been considered as an alternative to overcome some of these interoperability issues.rnThe presented work illustrates the pros and cons of using GNSS code measurements and Doppler measurements, in relative mode for V2X relative positioning. Given that carrier phase based methods such as Real-Time Kinematic (RTK) are subject to cycle slips, using code measurements only or code and Doppler measurements is a more attractive method of relative positioning that is also simpler to implement.