{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,12,23]],"date-time":"2025-12-23T10:01:57Z","timestamp":1766484117611,"version":"build-2065373602"},"reference-count":24,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2019,1,12]],"date-time":"2019-01-12T00:00:00Z","timestamp":1547251200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"The National Key Research and Development Program of China","award":["2016YFB0501803"],"award-info":[{"award-number":["2016YFB0501803"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>The continual miniaturization of mass-market sensors built in mobile intelligent terminals has inspired the development of accurate and continuous navigation solution for portable devices. With the release of Global Navigation Satellite System (GNSS) observations from the Android Nougat system, smartphones can provide pseudorange, Doppler, and carrier phase observations of GNSS. However, it is still a challenge to achieve the seamless positioning of consumer applications, especially in environments where GNSS signals suffer from a low signal-to-noise ratio and severe multipath. This paper introduces a dedicated android smartphone application called Walker that integrates the GNSS navigation solution and MEMS (micro-electromechanical systems) sensors to enable continuous and precise pedestrian navigation. Firstly, we introduce the generation of GNSS and MEMS observations, in addition to the architecture of Walker application. Then the core algorithm in Walker is given, including the time-differenced carrier phase improved GNSS single-point positioning and the integration of GNSS and Pedestrian Dead Reckoning (PDR). Finally, the Walker application is tested and the observations of GNSS and MEMS are assessed. The static experiment shows that, with GNSS observations, the RMS (root mean square) values of east, north, and up positioning error are 0.49 m, 0.37 m, and 1.01 m, respectively. Furthermore, the kinematic experiment verifies that the proposed method is capable of obtaining accuracy within 1\u20133 m for smooth and continuous navigation.<\/jats:p>","DOI":"10.3390\/rs11020139","type":"journal-article","created":{"date-parts":[[2019,1,14]],"date-time":"2019-01-14T12:20:07Z","timestamp":1547468407000},"page":"139","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":29,"title":["Walker: Continuous and Precise Navigation by Fusing GNSS and MEMS in Smartphone Chipsets for Pedestrians"],"prefix":"10.3390","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-4946-3407","authenticated-orcid":false,"given":"Feng","family":"Zhu","sequence":"first","affiliation":[{"name":"School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1030-0678","authenticated-orcid":false,"given":"Xianlu","family":"Tao","sequence":"additional","affiliation":[{"name":"School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China"}]},{"given":"Wanke","family":"Liu","sequence":"additional","affiliation":[{"name":"School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China"}]},{"given":"Xiang","family":"Shi","sequence":"additional","affiliation":[{"name":"School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China"}]},{"given":"Fuhong","family":"Wang","sequence":"additional","affiliation":[{"name":"School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China"}]},{"given":"Xiaohong","family":"Zhang","sequence":"additional","affiliation":[{"name":"School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China"},{"name":"Collaborative Innovation Center for Geospatial Technology, Wuhan University, Wuhan 430079, China"}]}],"member":"1968","published-online":{"date-parts":[[2019,1,12]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Verhagen, S., Odijk, D., Teunissen, P.J.G., and Huisman, L. (2010, January 8\u201310). Performance improvement with low-cost GNSS receivers. Proceedings of the 2010 5th ESA Satellite Navigation Technologies and European Workshop on GNSS Signals and Signal Processing (NAVITEC), Noordwijk, The Netherlands.","DOI":"10.1109\/NAVITEC.2010.5708015"},{"key":"ref_2","unstructured":"Pesyna, K.M.J., Heath, R.W.J., and Humphreys, T.E. (2014, January 8\u201312). Centimeter positioning with a smartphone-quality GNSS antenna. Proceedings of the ION GNSS 2014, Tampa, FL, USA."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Humphreys, T.E., Murrian, M., van Diggelen, F., Podshivalov, S., and Pesyna, K.M.J. (2016, January 11\u201314). On the feasibility of cm-accurate positioning via a smartphone\u2019s antenna and GNSS chip. Proceedings of the IEEE\/ION PLANS 2016, Savannah, GA, USA.","DOI":"10.1109\/PLANS.2016.7479707"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"17329","DOI":"10.3390\/s150717329","article-title":"NLOS correction\/exclusion for GNSS measurement using RAIM and city building models","volume":"15","author":"Hsu","year":"2015","journal-title":"Sensors"},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Lee, Y.E., Tao, A.L., and Jan, S.S. (2016, January 12\u201316). Combined Satellite Selection Algorithm and Road Model for GNSS in Constrained Environments. Proceedings of the ION GNSS 2016, Portland, OR, USA.","DOI":"10.33012\/2016.14802"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1281","DOI":"10.1109\/SURV.2012.121912.00075","article-title":"A survey of indoor inertial positioning systems for pedestrians","volume":"15","author":"Harle","year":"2015","journal-title":"IEEE Commun. Surv. Tutor."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Correa, A., Barcelo, M., Morell, A., and Vicario, J.L. (2017). A review of pedestrian indoor positioning systems for mass market applications. Sensors, 17.","DOI":"10.3390\/s17081927"},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Pham, V.T., Nguyen, D.A., Dang, N.D., Pham, H.H., Tran, V.A., Sandrasegaran, K., and Tran, D.T. (2018). Highly Accurate Step Counting at Various Walking States Using Low-Cost Inertial Measurement Unit Support Indoor Positioning System. Sensors, 18.","DOI":"10.3390\/s18103186"},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Kang, J., Lee, J., and Eom, D. (2018). Smartphone-Based Traveled Distance Estimation Using Individual Walking Patterns for Indoor Localization. Sensors, 18.","DOI":"10.3390\/s18093149"},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Lachapelle, G., Gratton, P., Horrelt, J., Lemieux, E., and Broumandan, A. (2018). Evaluation of a Low Cost Hand Held Unit with GNSS Raw Data Capability and Comparison with an Android Smartphone. Sensors, 18.","DOI":"10.3390\/s18124185"},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Crosta, P., Zoccarato, P., Lucas, R., and De Pasquale, G. (2018, January 24\u201328). Dual Frequency mass-market chips: test results and ways to optimize PVT performance. Proceedings of the ION GNSS 2018, Miami, FL, USA.","DOI":"10.33012\/2018.15882"},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Laurichesse, D., Rouch, C., Marmet, F.X., and Pascaud, M. (2017, January 25\u201329). Smartphone applications for precise point positioning. Proceedings of the ION GNSS 2017, Portland, OR, USA.","DOI":"10.33012\/2017.15149"},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Realini, E., Caldera, S., Pertusini, L., and Sampietro, D. (2017). Precise gnss positioning using smart devices. Sensors, 17.","DOI":"10.3390\/s17102434"},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Riley, S., Lentz, W., and Clare, A. (2017, January 25\u201329). On the path to precision\u2014Observations with android GNSS observables. Proceedings of the ION GNSS 2017, Institute of Navigation, Portland, OR, USA.","DOI":"10.33012\/2017.15244"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"70","DOI":"10.1007\/s10291-018-0736-8","article-title":"Quality assessment of GNSS observations from an android N smartphone and positioning performance analysis using time-differenced filtering approach","volume":"22","author":"Zhang","year":"2018","journal-title":"GPS Solut."},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Navarro-Gallardo, M., Bernhardt, N., Kirchner, M., Musial, J.R., and Sunkevic, M. (2017, January 25\u201329). Assessing Galileo Readiness in Android Devices Using Raw Measurements. Proceedings of the ION GNSS 2017, Portland, OR, USA.","DOI":"10.33012\/2017.15183"},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Gioia, C., Gaglione, S., and Borio, D. (2015, January 4\u20135). Inter-system Bias: Stability and impact on multi-constellation positioning. Proceedings of the 2015 IEEE Metrology for Aerospace, Benevento, Italy.","DOI":"10.1109\/MetroAeroSpace.2015.7180635"},{"key":"ref_18","unstructured":"Ciro, G., Joaquim, F.G., and Fabio, P. (2014, January 3\u20135). Estimation of the GPS to Galileo Time Offset and its validation on a mass market receiver. Proceedings of the 2014 7th ESA Workshop on Satellite Navigation Technologies and European Workshop on GNSS Signals and Signal Processing (NAVITEC), Noordwijk, The Netherlands."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1279","DOI":"10.1007\/s00190-016-0925-6","article-title":"A statistical characterization of the galileo-to-gps inter-system bias","volume":"90","author":"Gioia","year":"2016","journal-title":"J. Geod."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"7","DOI":"10.4236\/pos.2015.62002","article-title":"An Improved Model for Single-Frequency GPS\/GALILEO Precise Point Positioning","volume":"6","author":"Afifi","year":"2015","journal-title":"Positioning"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"335","DOI":"10.1007\/s10291-014-0425-1","article-title":"Time-differenced carrier phases technique for precise GNSS velocity estimation","volume":"19","author":"Freda","year":"2015","journal-title":"GPS Solut."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1305","DOI":"10.1109\/TAES.2007.4441741","article-title":"User-level reliability monitoring in urban personal satellite-navigation","volume":"43","author":"Kuusniemi","year":"2007","journal-title":"IEEE Trans. Aerosp. Electron. Syst."},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Zaliva, V., and Franchetti, F. (2014, January 4\u20139). Barometric and GPS altitude sensor fusion. Proceedings of the 2014 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), Florence, Italy.","DOI":"10.1109\/ICASSP.2014.6855063"},{"key":"ref_24","first-page":"336","article-title":"GPS\/Barometer augmented navigation system: Integration and integrity monitoring","volume":"74","author":"Gaglione","year":"2015","journal-title":"Metrol. Aerosp."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/11\/2\/139\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T12:25:31Z","timestamp":1760185531000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/11\/2\/139"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,1,12]]},"references-count":24,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2019,1]]}},"alternative-id":["rs11020139"],"URL":"https:\/\/doi.org\/10.3390\/rs11020139","relation":{},"ISSN":["2072-4292"],"issn-type":[{"type":"electronic","value":"2072-4292"}],"subject":[],"published":{"date-parts":[[2019,1,12]]}}}