Date Published: April 18, 2019
Publisher: Public Library of Science
Author(s): Tomasz Szot, Cezary Specht, Mariusz Specht, Pawel S. Dabrowski, Nabil Alshurafa.
Achieving single meter positioning accuracy by portable mobile devices still poses a major challenge to the satellite signal receivers constructors, despite gradual constellation completing process and the progress achieved in last decades. Nowadays popular smartphones are multifunctional devices that serve also as a personal navigation tool in navigation and sport activities using the global navigation satellite systems (GNSS) receivers installed. It would seem that introducing newer models to the global market would cause constant progress in the accuracies obtained, however, the study results do not confirm that. This study focused on Galaxy series smartphones of Samsung, one of the leading manufacturers worldwide, to examine its technological progress. The aim was to verify the thesis using statistical models and analyses to compare succeeding generations of smartphones on six devices from the series. The authors conducted two synchronous stationary measurement campaigns of 24 and 12 hours with one-second interval in obstacle-free environment which provided 70000+ and 30000+ statistical samples of position measurements. The reference values of true smartphones coordinates were determined by means of state-of-the-art precise surveying instruments and geodetic calculations. The results indicate that two newest generations of the Galaxy series included in the research, namely S6 and S7, obtained lower accuracies than their predecessors. Against the backdrop of lack of public availability of smartphones technical parameters, the conducted research results are relevant especially to smartphones positioning service users community.
Smartphones have become an inherent element of daily life of developed societies in the past decade. With comprehensive accessories, readily installable applications connected to the internet, they have in fact become upgraded multifunctional devices that help process, store and disseminate various types of information, regardless of location and time. Their increasing capacities have made them the number one worldwide sale in 2013, as compared to other mobile phones . According to recent global studies, they are owned by 72% of adults in the United States, 67% in Canada, 77% in Australia , and the estimated total number of users will reach nearly 2.9 billion in 2020 . The leading global vendors are Samsung and Apple, with approximately 18% of the global market each .
The assumption of the study was to conduct the measurement continuously for a period of 24 hours with a one-second interval in the same conditions. As a result, a representative synchronous sample of statistical data that describe the smartphones positioning process was obtained. The collected data allowed to carry out a reliable comparative accuracy analysis. By determining the coordinates of the GNSS receivers of the phones, the previously described accuracy measures of positioning could be related to actual values (predictable accuracy). Due to the limited volume of the article, statistics of errors in the repeatable position were deliberately omitted. The applied approach can be found in the geodesy and navigation literature. For the evaluation of several adopted measures of accuracy values a Mathcad sheet was created (Table 3). Due to the achieved low accuracy of the positioning of Samsung Galaxy S6 and S7 phones additional verification session was conducted (Table 4).
Table 5 shows the global scientific research carried out over the last few years, during which the accuracy of static (stationary method) position determination in the group of smartphones and sport-recreational receivers was assessed. It is worth adding that there is much more research on the assessment of kinematic position determination accuracy [43–47],  than stationary described in this research.
While addressing the issue of accuracy of GNSS receivers implemented in smartphones, the authors realised that these are very specific measurement devices. The final effect of displaying the desired information (a pair of coordinates, speed, direction, position on the electronic map) is affected by a number of factors that can be assigned to two groups: (1) those who are fully or partially user-dependent (software update and selection, choice of specific software options, firmware update in the device, etc.); and (2) factors that the user cannot alter (the quality of components installed in the receiver, built-in systems software, GNSS system errors, etc.). The popularity of smartphones and their use in navigational applications is widespread in public, but just few nonprofessional users are aware of the complexity of the underlying process, based on the knowledge and experience of hardware and software manufacturers. It would be helpful if smartphones manufacturers were to act like universal GNSS data loggers manufacturers (e.g. Qstarz, Holux) and published technical information on the achieved accuracy or on implemented GNSS chipsets. Unfortunately, smartphone specifications are missing such data. Hence, the major objective of this article has been to bridge the gap.