###### Abstract
[8] showed, experimentally, that the geometry for GPS POD is extraordinarily strengthened when the LEO satellites are included as moving tracking stations. This means that we can utilize LEO satellites to improve the accuracy of GPS orbits considerably when there are not enough ground stations. If there are only 21 globally distributed stations plus 3 LEO satellites, the orbits of GPS satellites are still more accurate than when only 43 stations are used. The improvement in GPS orbits is related to the orbit configuration of LEO satellites. The BDS-3 satellites, with inter-satellite link (ISL) equipment, can realize high-precision Ka-band ranging and communication between MEO satellites or between GEO, IGSO, and MEO satellites [9]. The purpose of the ISL is to enable the autonomous orbit determination of navigation satellites and to improve the uneven distribution of ground-monitoring stations for BDS-3 [10]. The use of ISL data and ground station observation data to jointly determine the orbit can improve the orbital accuracy of BDS satellites [4; 11; 12]. The LEO constellation enhances the orbit accuracy of the BDS-3 constellation, and highly accurate LEO satellite orbits are crucial. Onboard GNSS receivers are now mainly used to determine the orbit of LEO satellites [13], and there are three main types of POD methods for LEO satellites: dynamic orbit determination [14], kinematic precise orbit determination [15], and reduced-dynamic orbit determination [16]. Reduced-dynamic orbit determination adjusts the weight ratio between the satellite's dynamics information and geometric information through process noise. Usually, an additional perturbation force model is introduced during the simplified reduced-dynamic orbit determination to absorb satellite perturbation force model errors and unmodelled errors. Thanks to the International GNSS Service's (IGS) final precise ephemeris and clock products, a post-processing orbiting accuracy of 1-2 cm can be achieved for LEO satellites [17; 18]. Integrated orbit determination is the use of ground-based GNSS observations and satellite-based observations to simultaneously solve the GNSS satellite, and the LEO satellite orbit clock-offset, thus improving the overall performance of the navigation satellite [19]. Integrated satellite ground orbit using satellite-based observation data has been performed by scholars. [PERSON] et al. [20] used PANDA (position and navigation data analysis) software for the integrated determination of GPS and CHAMP satellite orbits, showing that the accuracy of GPS orbit results can reach about 30 mm (using the IGS final precise ephemeris as reference), and the accuracy of CHAMP satellite orbit results is around 114 mm (using the GeoForschungsZentrum Potsdam (GFZ) final precise ephemeris as reference). [PERSON] et al. [21] use GEO/LEO integrated orbit determination, and the improvement in the LEO orbit is obvious. ISL data from multiple GEO satellites and LEO satellites can encrypt continuously trackable arcs, further improving orbit accuracy. [PERSON] et al. [22] used satellite-based GPS observations for integrated orbit determination to significantly improve the GPS satellite orbit accuracy compared to using only ground-based tracking station observations. [PERSON] et al. [4] verified that adding ISL data reduces the dependence on ground stations, and that any improvement in the observation geometry by addingISL data has a positive impact on the POD. [PERSON] et.al. [23] focus on analyzing the LEO enhanced global navigation satellite system (LeGNSS) advantages and challenges for precise orbit and clock determination, precise point positioning (PPP) convergence, Earth rotation parameter estimation, and global ionosphere modeling. [PERSON] et al. [24], using LEO satellites with multi-GNSS integrated orbit determination, found that by using 8 globally distributed stations, the accuracy of GNSS satellite orbits can reach the sub-centimeter level, which is comparable to the results of more densely integrated POD, with 65 stations worldwide.