# Assessment of IRNSS-Only Data Processing: Availability, Single-Frequency SPP and Short-Baseline RTK
###### Abstract  
The Indian Regional Navigation Satellite System (IRNSS) currently can provide independent positioning services with eight in-orbit satellites. This study provides a comprehensive assessment of IRNSS-only data processing, including the availability of satellite constellation, the performance of single-frequency single point positioning (SPP), and the performance of single-frequency short-baseline real-time kinematic (RTK) positioning. Regarding the availability of IRNSS-only case in its primary service areas, the average number of visible satellites is 6-8, and the average Position Dilution of Precision (PDOP) value falls between 3.3 and 6.2, under a service rate of nearly 100.0%. The datasets from 14 stations located in the IRNSS service areas spanning a week are used for position determination. The results show that under the IRNSS single-system case, the positioning accuracy of the SPP is 6.031, 6.015, and 9.668 m in the east, north, and up directions, respectively, and the mean positioning bias of short-baseline RTK is 5.4, -21.1, and -0.2 mm with a standard deviation (STD) error of 7.8, 19.2, and 29.0 mm in the three directions, respectively. For comparative analysis, the results of the GPS single-system and GPS/IRNSS dual-system combination cases are also presented. The positioning performance of IRNSS is inferior to that of GPS, and the performance improvement of GPS/IRNSS dual-system integrated solutions over GPS single-system solutions is not significant. Furthermore, based on the GPS/IRNSS dual-system solutions, the inter-system bias estimates from SPP, the code observation residuals from SPP, and the carrier phase observation residuals from short-baseline RTK are characterized. IRNSS; availability; single point positioning; real-time kinematic positioning 20221426220222142622214222214222142221422214222142221422214222142221422214222142221422214222142221422221422221422214222214222214222142222142  
IRNSS L5. In addition, IRNSS L5 signals could present larger impacts from multipath errors compared to the GPS L5. The orbit determination method of IRNSS was investigated in [PERSON] et al. [5], and they solved the parameters of satellite state vectors and satellite clocks using batch least squares (BLS) and extended Kalman filter (EKF). The results of orbit determination with BLS were poor during clock jump events, and the errors of orbit determination with EFK would accumulate, resulting in poor results when conducting a long period of data processing. Based on these results, they presented a combination strategy with the use of BLS and EKF, which could limit the user equivalent range error (UERE) within an acceptable level. IRNSS provides a standard positioning service (SPS) for civil users and a restricted service (RS) for authorized users in the service areas, using differently modulated L5 and S signals, with a binary phase-shift keying (BPSK) modulation for SPS users, and with a binary offset carrier (BOC) modulation for RS users [6]. Several studies have analyzed the positioning accuracy of IRNSS. [PERSON] et al. [7] analyzed the dilution of precision (DOP) and single point positioning (SPP) solutions in the service areas of IRNSS. The analysis used approximate height to develop a height-constrained model when the geodetic height of the receiver does not change significantly. The results showed that the accuracy improvements coming with the height constraints could increase with the increment of distance from the equator, and those in the north and east directions could reach up to 28.1% and 36.2%, respectively. Regarding the DOP over the primary service areas, the position DOP (PDOP) values were smaller than four, and the horizontal DOP (HDOP) values were less than two. [PERSON] et al. [8] carefully analyzed the availability of IRNSS under open and occluded environments by using simulation methods, and it was demonstrated that users could observe 6-7 IRNSS satellites in primary service areas and over four satellites in secondary service areas.