Estimating Urban Road GPS Environment Friendliness with Bus Trajectories: A City-Scale Approach †.

Liantao Ma,Junfeng Zhao,Chaohe Zhang,Jiangtao Wang,Guangju Peng,Yasha Wang,Chao Chen

doi:10.3390/s20061580

Abstract

GPS is taken as the most prevalent positioning system in practice. However, in urban areas, as the GPS satellite signal could be blocked by buildings, the GPS positioning is not accurate due to multi-path errors. Estimating the negative impact of urban environments on GPS accuracy, that is the GPS environment friendliness (GEF) in this paper, will help to predict the GPS errors in different road segments. It enhances user experiences of location-based services and helps to determine where to deploy auxiliary assistant positioning devices. In this paper, we propose a method of processing and analysing massive historical bus GPS trajectory data to estimate the urban road GEF integrated with the contextual information of roads. First, our approach takes full advantage of the particular feature that bus routes are fixed to improve the performance of map matching. In order to estimate the GEF of all roads fairly and reasonably, the method estimates the GPS positioning error of each bus on the roads that are not covered by its route, by taking POIinformation, tag information of roads, and building layout information into account. Finally, we utilize a weighted estimation strategy to calculate the GEF of each road based on the GPS positioning performance of all buses. Based on one month of GPS trajectory data of 4835 buses within the second ring road in Chengdu, China, we estimate the GEF of 8831 different road segments and verify the rationality of the results by satellite maps, street views, and field tests.

Highlights

GPS is widely used in many location-based services (LBS), such as traffic, tourism, and social interaction
The multipath effect refers to the phenomenon in urban canyons; GPS signals cannot reach the receiver through the line of sight (LoS), but are reflected via the building surface or the ground
According to the indication generated in the statement of the National Marine Electronics Association (NMEA), the locating information included in the GPS

Summary

Introduction

GPS is widely used in many location-based services (LBS), such as traffic, tourism, and social interaction. The error of GPS positioning has negative impacts on LBS users and even leads to decision-making mistakes. Recent works [5,6,7,8] confirmed by reassuring experiments that the multipath effect, especially in a built-up urban area, has a major impact on the precision of GPS positioning. According to the indication generated in the statement of the National Marine Electronics Association (NMEA), the locating information included in the GPS raw data can be used to measure satellite constellations’ geometry errors and receivers’ instrumental errors to some extent. It is not enough to measure the multipath error or GPS positioning error definitely based only on such information [7,9]

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Methods

Results

Conclusion