); yijian,[EMAIL_ADDRESS] (J.Y. ); 18269524590163.com (Z.H. ); [EMAIL_ADDRESS] (Z.D. ); [EMAIL_ADDRESS] (Y.L. ); [EMAIL_ADDRESS] (Y.L. ); [EMAIL_ADDRESS] (Z.L. ); [EMAIL_ADDRESS] (J.Z.) [PERSON]  
1 School of Electronic Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China; [EMAIL_ADDRESS] (W.L. ); yijian,[EMAIL_ADDRESS] (J.Y. ); 18269524590163.com (Z.H. ); [EMAIL_ADDRESS] (Z.D. ); [EMAIL_ADDRESS] (Y.L. ); [EMAIL_ADDRESS] (Y.L. ); [EMAIL_ADDRESS] (Z.L. ); [EMAIL_ADDRESS] (J.Z.) [PERSON]  
1 School of Electronic Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China; [EMAIL_ADDRESS] (W.L. ); yijian,[EMAIL_ADDRESS] (J.Y. ); 18269524590163.com (Z.H. ); [EMAIL_ADDRESS] (Z.D. ); [EMAIL_ADDRESS] (Y.L. ); [EMAIL_ADDRESS] (Y.L. ); [EMAIL_ADDRESS] (J.Z.) [PERSON]  
1 School of Electronic Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China; [EMAIL_ADDRESS] (W.L. ); yijian,[EMAIL_ADDRESS] (J.Y. ); 18269524590163.com (Z.H. ); [EMAIL_ADDRESS] (Z.D. ); [EMAIL_ADDRESS] (Y.L. ); [EMAIL_ADDRESS] (Z.D. ); [EMAIL_ADDRESS] (Y.L. ); [EMAIL_ADDRESS] (J.Z.) [PERSON]  
1 School of Electronic Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China; [EMAIL_ADDRESS] (W.L. ); yijian,[EMAIL_ADDRESS] (J.Y. ); 18269524590163.com (Z.H. ); [EMAIL_ADDRESS] (Z.D. ); [EMAIL_ADDRESS] (Y.L. ); [EMAIL_ADDRESS] (Z.L. ); [EMAIL_ADDRESS] (Y.L. ); [EMAIL_ADDRESS] (Z.L. ); [EMAIL_ADDRESS] (J.Z.) China Satellite Network Exploration Co., Ltd., Chongqing 401120, China; [EMAIL_ADDRESS] (Y.L.) [PERSON]  
1 School of Electronic Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China; [EMAIL_ADDRESS] (W.L. ); yijian,[EMAIL_ADDRESS] (J.Y. ); 18269524590163.com (Z.H. ); [EMAIL_ADDRESS] (Z.D. ); [EMAIL_ADDRESS] (Y.L. ); [EMAIL_ADDRESS] (Y.L. ); [EMAIL_ADDRESS] (J.Z.) China Satellite Network Exploration Co., Ltd., Chongqingone of the important solutions. Terrestrial-based mobile communication systems primarily serve users through a base station (BS), utilizing a communication model of fixed BSs and moving users. In this model, a cell handover can be determined by measuring the quality of the received BS signal power [2;3]. Unlike terrestrial-based mobile communication systems, the mobile phone directly to satellite cell (MPDTSC) concept utilizes a model with a high-speed moving satellite and a moving user. This means that even if the user remains motionless, the beams of the satellite covering the user will move rapidly, frequently requiring the user to select an appropriate new satellite and implement the handover to its beam in order to maintain continuous and reliable communication [4;5]. Based on the orbits of satellites within constellations and their ephemerides, users can predict which satellites will serve them in these corresponding locations, thereby supporting the selection of suitable satellites for access. Here, the ephemeris directly conveys the information on the positions and velocities of these satellites within LEO-SIN. This information can contribute to the estimation of the Doppler frequency offset (DFO), which is used to compensate for and resist the satellite channel response degradations [6;7]. Additionally, the ephemeris can be used to calculate the remaining time the satellite serves as a contact point to help with radio resource control (RRC), random access (RA), and hybrid automatic repeat requests (HARQs) [8]. In the case of an orbital altitude of about 300-1200 km with a minimum elevation angle of 30\({}^{\circ}\), each satellite in orbit can serve a user for approximately 3-10 min, implying that the orbit extrapolation error must not be higher than 20 m.  
The existing research on orbit extrapolation relies on modeling based on astrodynamics, which describes characteristics related to the satellite's orbit and position, such as inclination, right ascension of the ascending node, eccentricity, and mean anomaly.