# Signal Design and Compatibility Assessment for LEO Navigation Augmentation System +
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China Academy of Space Technology (Xi'an), Xi'an 710100, China; [EMAIL_ADDRESS] (Y.W. ); [EMAIL_ADDRESS] (L.B. ); [EMAIL_ADDRESS] (Y.M.) [PERSON]  
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China Academy of Space Technology (Xi'an), Xi'an 710100, China; [EMAIL_ADDRESS] (Y.W. ); [EMAIL_ADDRESS] (L.B. ); [EMAIL_ADDRESS] (Y.M.) [PERSON]  
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China Academy of Space Technology (Xi'an), Xi'an 710100, China; [EMAIL_ADDRESS] (Y.W. ); [EMAIL_ADDRESS] (L.B. ); [EMAIL_ADDRESS] (Y.M.) [PERSON]  
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China Academy of Space Technology (Xi'an), Xi'an 710100, China; [EMAIL_ADDRESS] (Y.W. ); [EMAIL_ADDRESS] (L.B. ); [EMAIL_ADDRESS] (Y.M.) [PERSON]  
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China Academy of Space Technology (Xi'an), Xi'an 710100, China; [EMAIL_ADDRESS] (Y.W. ); [EMAIL_ADDRESS] (L.B. ); [EMAIL_ADDRESS] (Y.M.) [PERSON]  
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China Academy of Space Technology (Xi'an), Xi'an 710100, China; [EMAIL_ADDRESS] (Y.W. ); [EMAIL_ADDRESS] (L.B. ); [EMAIL_ADDRESS] (Y.M.) [PERSON]  
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China Academy of Space Technology (Xi'an), Xi'an 710100, China; [EMAIL_ADDRESS] (Y.W. ); [EMAIL_ADDRESS] (L.B. ); [EMAIL_ADDRESS] (Y.M.) [PERSON]  
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China Academy of Space Technology (Xi'an), Xi'an 710100, China; [EMAIL_ADDRESS] (Y.W. ); [EMAIL_ADDRESS] (L.B. ); mengys_504@163. The LEO navigation can be divided into two categories in terms of implementation methods. One is to provide services through existing payloads, and the other is to provide services through newly added dedicated LEO navigation augmentation payloads. For the first category, represented by Iridium Next STL [9], the unique communication and navigation fusion signal is designed to provide positioning and timing services. Reference [10] designed a communication and navigation fusion signal based on the characteristics of Starlink signals. For the second category, it is mainly achieved by broadcasting dedicated LEO navigation augmentation signals to provide services through LEO navigation augmentation payloads. Represented by XONA Company in the United States, it plans to build the Pulsar constellation of 300 LEO satellites and achieve fast convergence, high precision, and high-security PNT services by broadcasting LEO navigation augmentation signals at L and C frequency bands [11]. Beijing Future Navigation Technology Co. Ltd. proposes to build a dedicated LEO navigation augmentation system consisting of 150 LEO satellites called CENTISPACE. The goal is to achieve positioning accuracy of <10 cm and PPP convergence time of 1 min [12]. CENTISPACE broadcasts the dual-frequency navigation augmentation signals in the L1 and L2 frequency bands. In orbit, test results indicate the effectiveness of LEO navigation augmentation [13]. In addition, the Luojia-1 experimental satellite of Wuhan University and the Tianxiang-1 A/B satellite launched by China Electronics Technology Group Corporation in 2019 have conducted performance verification by carrying LEO navigation augmentation payloads and broadcasting dual-frequency signals in the L-band [14; 15; 16]. In order to exploit the LEO navigation augmentation system to accelerate PPP convergence speed, it is necessary to broadcast dedicated LEO dual-frequency navigation augmentation signals. The design of the LEO navigation augmentation signal needs to meet different requirements [17]. This paper focuses on the design of the LEO navigation augmentation signal. In Section 2, the design requirements for LEO navigation augmentation signals are analyzed. In Section 3, signal design schemes are presented to meet the key design requirements.