GNSS Messaging Scheme for Vehicle-to-Vehicle (V2V) and Vehicle-to-Infrastructure (V2I) Communications Based Precise Positioning with Low-Cost Hardware

Chaminda Basnayake

Abstract:	Vehicle-to-Vehicle (V2V) and Vehicle-to-Infrastructure (V2I) communications based Active Safety Driver Assistance Systems (ASDAS) have emerged as the next generation low-cost alternative of automotive safety systems. These systems require various levels of positioning capabilities ranging from which road, which lane, to where in lane. This paper introduces a flexible GNSS message scheme based on the RTCM (Radio Technical Committee for Maritime Services) v3.0 standards that supports the aforementioned accuracy requirements of such systems. The proposed message scheme and data format include a message header with a vehicle specific identifier, vehicle states such as position, heading, and velocity, and a block of RTCM version 3.0-based raw GNSS (Global Navigation Satellite System) data intended for precise positioning using Real-time Kinematic (RTK) techniques. As confirmed by the results, the proposed header alone is able to support which road positioning application needs with compatible hardware. Applications that require which lane or better positioning accuracies may use the rest of the message to refine the positioning accuracy using one of several methods investigated in this paper. The proposed block-based data exchange enables faster processing of data from a large number of vehicles efficiently and enables the identification of a subset of neighboring vehicles which may be precisely positioned. This is of great importance considering the processing needs of RTK-type positioning and the limited processing resources available in contemporary automotive platforms. The header block in the scheme also allows the incorporation of in-vehicle sensor integrated vehicle state information into the system without any modifications irrespective of GNSS availability. The scheme can also be extended to include GPS L2C, L5 and Galileo signals with backward compatibility. The tests with low-cost GPS show that better than 2 m relative positioning accuracy is achieved 90% of the time a GPS-only reference relative position solution is available. The reference solution in this research was generated using top-of-the line dual frequency GPS receivers which are typically used for high quality precise positioning. Better than 1 m accuracy was achieved around 86% of the time when using carrier-based RTK techniques in highway environments with predominantly open sky conditions. Further deteriorations were observed in freeway tests with frequent visibility interruptions and possibly under the worst GPS constellation availability conditions experienced in the region (maximum of 5 satellites) where 1 m accuracy level was achieved only for 65% of the time. It is noted that these statistics were generated using single frequency production-type GPS hardware without any alternative sensor integration or aiding.
Published in:	Proceedings of the 20th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2007) September 25 - 28, 2007 Fort Worth Convention Center Fort Worth, TX
Pages:	1436 - 1446
Cite this article:	Basnayake, Chaminda, "GNSS Messaging Scheme for Vehicle-to-Vehicle (V2V) and Vehicle-to-Infrastructure (V2I) Communications Based Precise Positioning with Low-Cost Hardware," Proceedings of the 20th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2007), Fort Worth, TX, September 2007, pp. 1436-1446.
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