## 1 Introduction
Signal errors due to reflectors such as high-rise buildings or mountains may reach the kilometer level [8]. In addition, TC schemes cannot provide effective corrections when the GNSS signal is completely blocked. Therefore, robust navigation schemes for environments with severe degradation in GNSS performance have become the focus of researchers' attention. A common approach to solving such problems is to add additional sensors. For example, [PERSON] et al. successfully improved the precision of navigation positioning by integrating 3D laser radar into the navigation system [9]. The radar also reduces the drift of the inertial navigation system (INS) during long-term GNSS interruptions [10; 11]. [PERSON] et al. captured environmental scenes in urban anyons using fisheye cameras, matched them with satellite positions through calculation, and excluded invisible satellites, thus achieving better filtering performance [12]. [PERSON] and [PERSON] addressed the limitations of the GNSS by employing 3D mapping techniques [13; 14]. [PERSON] and [PERSON], on the other hand, used Ultra-Wide-Band (UWB) technology to cope with the insufficient number of visible GNSS satellites [15; 16]. Some studies have intended to mitigate the impact of degraded GNSS environments by combining information from additional sensors, such as cameras and laser scanners [17; 18; 19; 20]. Although the aforementioned approaches can mitigate the impact of GNSS-restricted environments to some extent, the simple addition of sensors would significantly increase costs. Moreover, certain sensors require extensive preliminary work, such as pre-built high-definition maps, which are not feasible in new environments. Additionally, the introduction of additional sensors also increases the complexity of algorithms, making it challenging to meet the higher navigation output frequency requirements of some carriers. In this study, the vertical gyro (VG) algorithm is employed to assist the TC scheme in navigation. The VG algorithm determines the maneuvering state based on the accelerometer output. When the carrier is stationary, moving at a constant speed,or experiencing low acceleration, the VG measurements can correct the horizontal attitude, providing the carrier with a certain level of accurate horizontal attitude reference. Within a certain time frame, the VG algorithm effectively suppresses the divergence of navigation solution results [21]. This algorithm does not require the addition of extra sensor equipment and does not impose a significant computational burden, thereby achieving the high-frequency output of navigation signals. In addition, with the development of the multi-constellation multi-frequency GNSS, the measurement update of the TC integrated GNSS/INS can use the multi-satellite pseudo-range, the pseudo-range rate, Doppler velocity, and other types of observations. If all of the visible satellite observation data are input into the filter, high-dimensional observation vector processing will consume great arithmetic power, and embedded processors may not be able to achieve real-time navigation output. Therefore, to ensure the real-time capability of the navigation system, it is necessary to select a subset of the observed satellites from all visible satellites. However, the research on satellite screening algorithms has been mainly focused on finding the best Geometric Dilution Precision Factor, which is generally regarded as the amplification of the measurement error, while the positioning accuracy of satellite navigation is also related to the User Equivalent Range Error [22]. In this paper, we present a weighted quasi-optimal satellite selection algorithm designed by considering other relevant terms that determine the accuracy of satellite navigation data and analyze the performance and efficiency of the method through comparison experiments with the optimal satellite selection algorithm.