Quantifying Position Accuracy of Multimodal Data from Global Positioning System–Enabled Cell Phones

Utilizing both Assisted GPS (A-GPS) techniques and new high-sensitivity embedded GPS hardware, mobile phones are now able to achieve positioning in harsh environments such as urban canyons and indoor locations where older embedded GPS chips could not. This paper presents an empirical analysis of the positional accuracy of location data gathered using a high-sensitivity GPS-enabled mobile phone. The performance of the mobile phone is compared to that of regular recreational grade GPS receivers. Availability of valid GPS position fixes on the mobile phones tested was consistently close to 100% both outdoors and indoors. During static outdoor testing, positions provided by the mobile phones revealed a median horizontal error of between 5 . 0 and 8 . 5 m, substantially larger than those for regular autonomous GPS units by a factor of 2 to 3. Horizontal errors during static indoor testing were larger compared to outdoors, but the difference in accuracy between mobile phones and regular GPS receivers was reduced. Despite the modest performance of A-GPS on mobile phones, testing under various conditions revealed that very large errors are not very common. The maximum horizontal error during outdoor testing never exceeded 30 metres and during indoor testing never exceeded 100 metres. Combined with the relatively consistent availability of valid GPS position fixes under varying conditions, the current study has confirmed the reliability of A-GPS on mobiles phones as a source of location information for a range of different LBS applications.

2020

This study investigates the position and speed errors of two models of a smartphone brand and their relationship with variables that can block or reflect GPS signal in urban environments. The Brand Samsung, models Galaxy S6 and A5, were used in two experiments: static and dynamic. Results suggest that location and speed errors are related to the day of the week, smartphone device, the smartphone application, and location technology. This study extends previous research by offering new clues about errors of smartphones in urban environments.

Transactions in Gis, 2009

The 3G iPhone was the first consumer device to provide a seamless integration of three positioning technologies: Assisted GPS (A-GPS), WiFi positioning and cellular network positioning. This study presents an evaluation of the accuracy of locations obtained using these three positioning modes on the 3G iPhone. A-GPS locations were validated using surveyed benchmarks and compared to a traditional low-cost GPS receiver running simultaneously. WiFi and cellular positions for indoor locations were validated using high resolution orthophotography. Results indicate that A-GPS locations obtained using the 3G iPhone are much less accurate than those from regular autonomous GPS units (average median error of 8 m for ten 20-minute field tests) but appear sufficient for most Location Based Services (LBS). WiFi locations using the 3G iPhone are much less accurate (median error of 74 m for 58 observations) and fail to meet the published accuracy specifications. Positional errors in WiFi also reveal erratic spatial patterns resulting from the design of the calibration effort underlying the WiFi positioning system. Cellular positioning using the 3G iPhone is the least accurate positioning method (median error of 600 m for 64 observations), consistent with previous studies. Pros and cons of the three positioning technologies are presented in terms of coverage, accuracy and reliability, followed by a discussion of the implications for LBS using the 3G iPhone and similar mobile devices.

Journal of Urban Technology, 2010

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IET Intelligent Transport Systems, 2010

Recent advancements in mobile technology allow global positioning system (GPS)-enabled cell phones to provide a variety of real-time location-based services. This study reports on the design, implementation and testing of such a service, the travel assistance device (TAD), that aids transit riders with special needs in using public transportation. TAD is a program that provides the rider with customised real-time audio, visual and tactile prompts for exiting the transit vehicle by announcing 'Get ready. . .' and 'Pull the cord now!' Additionally, TAD provides alerts to riders, their caretakers and travel trainers if a rider deviates from the planned route. A website allows easy access for the creation of new trip itineraries and allows authorised personnel to monitor the rider's location in real-time from any computer. While the TAD was designed to aid transit riders with special needs to increase their level of independence and their care-takers' level of security, any rider new to a transit system can use TAD for planning and executing trips with confidence and ease.

2012

Ubiquitous positioning and mobile location-based services in smart phones / Ruizhi Chen, editor. p. cm. Includes bibliographical references and index. Summary: "This book explores new research in smart phones with an emphasis on positioning solutions in smart phones, smart phone-based navigation applications, mobile geographical information systems, and related standards"-Provided by publisher.

International Journal of Navigation and Observation, 2017

Nowadays, a Global Navigation Satellite System (GNSS) unit is embedded in nearly every smartphone. This unit allows a smartphone to detect the user’s location and motion, and it makes functions, such as navigation, tracking, and compass applications, available to the user. Therefore, the GNSS unit has become one of the most important features in modern smartphones. However, because most smartphones incorporate relatively low-cost GNSS chips, their localization accuracy varies depending on the number of accessible GNSS satellites, and it is highly dependent on environmental factors that cause interference such as forests and buildings. This research evaluated the performance of the GNSS units inside two different models of smartphones in determining pedestrian locations in different environments. The results indicate that the overall performances of the two devices were related directly to the environment, type of smartphone/GNSS chipset, and the application used to collect the infor...

2010 IEEE Global Telecommunications Conference GLOBECOM 2010, 2010

Location information has become an important enabler for services that interacts with the physical environment. Focus has therefore been on providing accurate information on the user's position, but less on the reliability of the information. This paper gives a methodology to evaluate numerically the reliability of estimated positioning of mobile devices, and shows how the methodology can be applied to decide upon the trade-off between reliability and accuracy of location systems.

Use of spatial data for resource and information management, analysis and visual interpretation purposes, is increasingly getting popular with developments in geographic information system (GIS) and related technologies. Hence, collection of geo-tagged spatio-temporal data is a frequent practice, where the location information is mostly recorded using hand-held Global Positioning System (GPS) receivers. Many of these common applications do not require higher levels of spatial accuracy, although expensive and high accuracy GPS units are often used. The cost of such GPS units alone absorb significant proportions of the budgetary allocations restricting other essential expenses, especially for instances such as; census data collections for disaster management, health GIS applications, location tracking, data interpolation and mapping, etc. As the modern-day smart-phones consist of inbuilt GPS-units providing location information, this study evaluates the performance of integrated GPS units in smart-phones for location data recording. It also assesses the possibility of smart-phones to replace handheld GPS units for instances that do not demand high levels of location accuracy, especially due to the user-friendliness and convenience of managing records and sharing information. Accordingly, spatial information of 20 locations, including a permanent benchmark for validation purpose, were recorded in Bandaragama, Sri Lanka, using a Differential GPS (DGPS) unit, one handheld GPS unit and five smart-phones. The Open Data Kit (ODK) mobile application was used to record and transmit location data along with their attributes to a remote server for simultaneous updating of a database. A statistical analysis was performed on the recorded location data to evaluate the disparities, by considering the DGPS records as the reference. The smart-phones showed a horizontal error of ~6.5 m with respect to DGPS readings. Therefore, smart-phone location services are most suitable for the applications where the required horizontal accuracy level is not less than 10 m.

GeoScience Engineering

In recent years, there have been significant technological advances in the development of common mobile devices. This brought progress also in the area of positioning with these devices. Allowing access to raw GNSS observations recorded by mobile devices opened possibilities to apply advanced positioning techniques in order to achieve higher positioning accuracy. The paper describes the results of kinematic measurements of a singlefrequency Samsung Galaxy S10+ smartphone and a dual-frequency Samsung Galaxy Note10+ smartphone. Observations were repeatedly collected at a 1.76 km long test route in an urban environment at a pedestrian speed. Real-time positioning by autonomous method as well as collection of raw observations into RINEX format and their subsequent post-processing by differential techniques and Precise Point Positioning technique were realized. The achieved results were compared against a reference line representing the real trajectory and also against results of a geodetic grade GNSS receiver. Positioning accuracy of mobile devices ranged from the first decimetres to tens of metres, depending on the environment, tested smartphone and used post-processing technique. Dualfrequency smartphone Samsung Galaxy Note 10+ provided a better performance compared to the single-frequency device. Real-time positioning based on a simple autonomous technique and smoothing algorithm for route optimization reached lower positioning errors compared to all solutions based on collecting raw observations and their consequent post-processing with mentioned techniques.