Initial Assessment of BeiDou-3 B1I/B1C/B2a Triple-Frequency Signals with Android Smartphones

With the full operation of BeiDou-3 navigation satellite system, smartphone positioning services, one of the public applications of BeiDou system, are gradually becoming a new highlight. For the first time, we present an initial characterization and performance assessment for the BeiDou-3 B1I/B1C/B2a triple-frequency signals in smartphones. B1I/B1C/B2a triple-frequency signals from measurement receiver and smartphones with external antenna are also evaluated for comparison. The characteristics of the B1I, B1C and B2a signals are evaluated in terms of observed carrier-to-noise ratio, multipath, observation precision, and the linear combinations of B1I/B1C/B2a signals. The results demonstrate that the characteristics of triple-frequency signals in smartphones are inferior to those in measurement receivers in terms of carrier-to-noise ratio and observation precision. Fortunately, the code and phase precision of the B1C/B2a signals are higher than those of the B1I signal in smartphones, respectively. In addition, the analytical study of B1I/B1C/B2a triple-frequency linear combinations was given in terms of mitigating ionospheric delay and improving ambiguity resolution. Finally, the positioning results indicate that the horizontal and vertical RMS of single-point positioning for BeiDou-3 ionosphere-free combinations are 15.24 m and 19.65 m in average, respectively. The horizontal and vertical RMS of relative positioning using BeiDou-2/BeiDou-3 signals are 4.65 cm and 5.34 cm, respectively. Furthermore, combined BeiDou-3 and other GNSS are able to provide more reliable position services in GNSS-adverse environments.