Multipath tracking with LTE signals for accurate TOA estimation in the application of indoor positioning

ABSTRACT

Indoor positioning with high accuracy plays an important role in different application scenarios. As a widely used mobile communication signal, the Long-Term Evolution (LTE) network can be well received in indoor and outdoor environments. This article studies a method of using different reference signals in the LTE downlink for carrier phase time of arrival (TOA) estimation. Specifically, a solution is proposed and a multipath tracking Software Defined Receiver (SDR) is developed for indoor positioning. With our SDR indoor positioning system, the pilot signals of the LTE signals are firstly obtained by the coarse synchronization and demodulation. Then, with the assistance of the pilot signals, the time delay acquisition, the multipath estimating delay lock loop (MEDLL) algorithm, and the multipath anomaly detection are sequentially carried out to obtain navigation observations of received signals. Furthermore, to compare the performance of different pilot signals, the Secondary Synchronous Signals (SSS) and Cell Reference Signals (CRS) are used as pilot signals for carrier phase-based TOA estimation, respectively. Finally, to quantify the accuracy of our multipath tracking SDR, indoor field tests are carried out in a conference environment, where an LTE base station is installed for commercial use. Our test results based on CRS show that, in the static test scenarios, the TOA accuracy measured by the 1-σ error interval is about 0.5 m, while in the mobile environment, the probability of range accuracy within 1.0 m is 95%.

KEYWORDS:

• Long-Term Evolution (LTE)
• indoor positioning
• multipath estimation delay locked loop (MEDLL)
• carrier phase
• time of arrival (TOA)

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The code applied in this study has not been made public because it involves subsequent research. Original data from part of the experiment can be obtained on reasonable request by contacting Zhaoliang Liu (E-mail: [email protected]).

Additional information

Funding

The research was supported by The National Natural Science Foundation of China [grant number 42171417]; the Special Fund of Hubei Luojia Laboratory [grant number 220100008], and the Key Research and Development Program of Hubei Province [grant number 2021BAA166].

Notes on contributors

Zhaoliang Liu

ZhaoliangLiu received the MS degree from Wuhan University in 2020. He is currently a PhD student at the State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing at Wuhan University. His research interests include indoor positioning and navigation technology based on signal of opportunity, wireless communications, and the Internet of Things.

Liang Chen

LiangChen was a Senior Research Scientist with the Department of Navigation and Positioning, Finnish Geodetic Institute, Finland. He is currently a Professor with the State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, China. He has published over 70 scientific articles and five book chapters. His current research interests include indoor positioning, wireless positioning, sensor fusion, and location-based services.

Xin Zhou

XinZhou received the BS and MS degrees from Wuhan University in 2018 and 2020, respectively. He is currently pursuing the PhD degree in geodesy and survey engineering with the State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University. His research interests include indoor positioning and navigation technology based on signal of opportunity, wireless communications, and the Internet of Things.

Nan Shen

NanShen is currently a PhD student at the State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing at Wuhan University. His research interests focus on precise GNSS data processing, software-defined receiver.

Ruizhi Chen

RuizhiChen is a professor at the State Key Laboratory of Surveying, Mapping and Remote Sensing Information Engineering, Wuhan University, and director of the laboratory. His main research interests include smartphone ubiquitous positioning and satellite navigation and positioning.