A Joint Time-Frequency Channel Estimation Method for ICAN-Enabled LEO Satellites

Integrated Communication and Navigation (ICAN) has emerged as crucial technology for embedding navigation into communication waveforms for 6G satellite internet. The effective integration of communication and navigation poses the challenge in ICAN-enabled Low Earth orbit (LEO) satellites. Existing methods struggle to conduct accurate channel estimation when faced with the LEO high-dynamic channels. To address this issue, a joint time-frequency channel estimation method is proposed, which leverages the symmetry of the 2D cross-ambiguity function to perform precise and robust Doppler and delay discrimination. Due to direct utilization of communication intermediate results, it achieves the measurement limits while ensuring communication performance. In addition, a closed expression of the estimation mean square error is derived, effectively balancing the trade-off between communication and navigation within a single frame. Results show that the proposed method can control a delay and Doppler accuracy within 10 cm and 12 Hz, respectively, when the pilot ratio is 0.089 and Signal-to-Noise Ratio (SNR) is -10 dB, with an approximate 58.34% improvement over traditional Global Navigation Satellite Systems.