# Performance Analysis of BDS-5G Combined Precise Point Positioning
## 1 Introduction  
Precise point positioning (PPP) technology has broad application prospects owing to its simplicity of operation, all-weather global nature, and high accuracy [1, 2]; however, it suffers from limitations that cannot be ignored. First, the high orbital altitude of the navigation satellite constellation weakens the transmitted navigation signals during propagation, and PPP cannot provide continuous and reliable navigation and positioning services in signal-obscured areas such as indoors, forests, and urban canyons [3, 4]. Second, the geometric position of navigation satellites changes very slowly with respect to ground stations, and long convergence times do not satisfy certain fast and precise positioning requirements [5]. Fifth generation mobile communication technology (5G) provides new opportunities for the navigation and positioning business. Compared with fourth generation mobile communication technology, 5G has a larger bandwidth and higher frequency, which enables a more mature positioning performance [6]. In particular, the deployment of 5G base stations will also optimize the geometric configuration of navigation satellites and shorten the convergence time of PPP. In addition, compared with Bluetooth, Wi-Fi, and ultra-wideband (UWB), 5G is based on existing communication base stations and does not require additional base stations [7, 8], so it has a lower cost. Compared with inertial navigation system (INS), pedestrian dead reckoning (PDR) and other means, 5G positioning can avoid error accumulation [9, 10]. [PERSON] et al. derived the Cramer-Rao bound (CRB) for estimating position and rotation angle from 5G millimeter wave signals of a single transmitter in the presenceof scatterers [11]. Through simulation experiments, [PERSON] et al. found that the quality of 5G positioning results was mainly affected by two factors, namely, poor geometric distribution quality of 5G base stations and multipath propagation of 5G millimeter wave signals [12]. [PERSON] et al. proposed a method for suppressing multipath effects on urban canyons, tunnels and indoors, which is called Two-Stage Multipath Estimating Delay Lock Loop (TS-MEDLL) [13]. Experimental results show that the proposed new method is effective in reducing the positioning errors caused by multipath effects and outperforms existing methods in positioning based on 5G. Based on the measured data from indoor environments, [PERSON] et al. compared three different 5G TDOA positioning algorithms. It was learned through experiments that the indoor positioning accuracy could reach 0.289 m statically and 0.608 m dynamically [14]. [PERSON] et al. created a channel model and simulation framework based on 5G measurements in an open-office building and used the framework to study the positioning performance of several algorithms [15]. Positioning algorithms research on fused global navigation satellite systems (GNSS) and 5G technology is currently in its infancy. For example, [PERSON] et al. combined GNSS and 5G observations at the physical level and evaluated their positioning capabilities in an urban macrocellular environment [16]. They also combined this with a three-dimensional (3D) city map, using the vector information of buildings and receivers in the 3D city map to calculate the visibility of satellites, and eliminate low-quality satellite observations [17; 18]. The Fisher information matrix for the positioning system combined with GNSS and 5G was derived, and lower bounds for the errors of position, rotation and clock were calculated by [PERSON] et al. [19]. [PERSON] et al. developed a GNSS-5G positioning method based on inter-device communication and angular measurements, and demonstrated that it could improve positioning accuracy [20]. [PERSON] et al. processed GNSS and 5G data with machine learning methods to achieve seamless integration [21]. [PERSON] et al.