## 1 Introduction
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**System** & **Satellite Types** & **Signals** & **Number of Satellites** & **PRN** \\ \hline GPS & IIR & L1C/A, L1/L2 & 1 & G13 G20 G22 G16 G21 G19 G02 \\  & IIF & L1C/A, L2C, L5 & 11 & G17 G31 G12 G15 G25 G07 \\  & III & L1C/A, L2C, L5 & 11 & G01 G24 G27 G30 G06 G09 G03 \\  & IIF & L1C/A, L2C, L5 & 5 & G01 G26 G08 G10 G32 \\ \hline BDS-2 & GEO & B1I, B2I, B3I & 5 & C01 C02 C03 C04 C05 \\  & IGSO & B1I, B2I, B3I & 7 & C06 C07 C08 C09 C10 C13 C16 \\  & MEO & B1I, B2I, B3I & 3 & C11 C12 C14 \\ \hline  & & & & C19 C20 C21 C22 C23 C24 C25 \\ BDS-3 & MEO & B1I, B3I, B1C, B2a, B2b & 24 & C26 C27 C28 C29 C30 C32 C33 \\  & IGSO & B1I, B3I, B1C, B2a, B2b & 24 & C34 C33 C35 C36 C37 C41 C42 C43 \\  & IGSO & B1I, B3I, B1C, B2a, B2b & 3 & C38 C39 C40 \\ \hline  & & & & R01 R02 R03 R04 R05 R06 R07 \\ GLONASS & GLONASS-M & G1C, G2C & 20 & R08 R10 R12 R13 R14 R15 R16 \\  & GLONASS-M+ & G1C, G2C, L3 & 2 & R18 R19 R20 R22 R23 R24 \\  & GLONASS-K1 & G1C, G2C, L3 & 2 & R17 R21 \\ \hline Galileo & IOV & E1, E5a/b/ab & 4 & E11 E12 E19 E20 \\  & FOC & E1, E5a/b/ab, E6 & 22 & E01 E02 G03 E04 E05 E07 E08 E09 \\  & & E1, E5a/b/ab, E6 & 22 & E10 E13 E14 E15 E18 E22 E24 E26 \\  & & & & E27 E30 E31 E33 E34 E36 \\ \hline QZSS & GEO & L1C/A, L1C, L2C, L5 & 1 & J07 \\  & QZO & L1C/A, L1C, L2C, L5 & 3 & J01 J02 J03 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Available satellites of each system at the end of April 2022.  
clock offset accuracy of five GNSS systems satellites is still unknown and unrevealed, it is urgent to conduct a comprehensive evaluation and comparison of the broadcast ephemeris performance for five GNSS systems satellites. In terms of multi-GNSS positioning, the contribution of QZSS to the single-frequency PPP of GPS/BDS/GLONASS/Galileo satellites was studied by [PERSON] et al. [18]. The positioning performance of BDS/QZSS in the Asia-Pacific region was evaluated by [PERSON] et al. [11]. The precise positioning performance of QZSS and GPS in the Asia-Pacific region was investigated by [PERSON] [19]. The positioning performance of BDS-2/BDS-3 in the Asia-Pacific region was analyzed by [PERSON] et al. [20]. It can be seen that the previous studies about PPP in the Asia-Pacific region are mainly focused on single or dual systems, while the PPP performance of multi-GNSS in the Asia-Pacific region is still limited. In this contribution, multi-GNSS (GPS/GLONASS/Galileo/BDS-2/BDS-3/QZSS) observation data quality, broadcast ephemeris orbit, and clock offset performance and PPP performance in the Asia-Pacific region are investigated in detail. Based on the observation data from 10 Asia-Pacific MGEX stations, multi-GNSS broadcast ephemeris and precise satellite orbit and clock offset products, the observation data quality, broadcast ephemeris orbit, clock offset performance, and PPP performance in the Asia-Pacific region are evaluated and compared from DOY 283 to 289, in 2021. This paper is organized as follows: after this introduction, the observation data quality of five GNSS systems from 10 stations located in the Asia-Pacific region are investigated and analyzed in terms of carrier-to-noise-density ratio(C/N0) and pseudorange multipath in Section 2. The accuracy of the broadcast ephemeris orbit and clock offset and signal-in-space ranging errors (SISRE) of the five systems is investigated, evaluated, and compared in Section 3. The static and kinematic PPP performance of five GNSS systems in the Asia-Pacific region is evaluated and compared from convergence time and positioning accuracy in Section 4. Finally, the conclusions are presented in Section 5.