Performance Analysis of RSMA-Assisted Integrated Navigation and Communication Satellite Network

Tocompensate for the insufficient number of visible satellites in global navigation satellite systems (GNSS), an integrated navigation and communication (INAC) network utilizing a relay satellite with rate splitting multiple access (RSMA) is proposed. In this system, an MEO satellite transmits navigation signals to both the geostationary earth orbit (GEO) satellite and ground users. When the MEO satellite is blocked, the GEO relay satellite decodes and forwards (DF) both navigation and communication signals. All information is spread and transmitted using RSMA, where the public stream carries navigation information, and the private stream carries communication data. To further reduce interference between navigation and communication signals, a zero-forcing and maximum ratio transmission (ZF-MRT) precoding is introduced. At the receiver, the navigation signal is first decoded for pseudorange accuracy using a code tracking loop (CTL), and then the communication signal is decoded using successive interference cancellation (SIC). Channel models are first established for both direct links and multi-antenna relay links. Then, signal-to-interference-plus-noise ratio (SINR) expressions under ZF-MRT precoding are derived, from which analytical results for outage probability (OP) and pseudorange accuracy are derived. Simulation results show that the proposed scheme, benefiting from ZF-MRT precoding for enhanced diversity gain, outperforms single-antenna RSMA and NOMA in both OP and positioning accuracy. In addition, increasing transmit power or spreading code length can effectively enhance navigation signals and improve communication reliability, while increasing the Rician factor has a limited effect on positioning accuracy. Finally, despite some loss in spectral efficiency (SE) due to the use of spread spectrum, this network still serves as a valuable reference for the design of future INAC systems.