Analogue self-interference cancellation of co-frequency co-time unidirectional transponders for low earth orbit satellite systems

Abstract

In the era of beyond 5G and 6G, the application of low earth orbit (LEO) satellites and space Internet techniques has become a hot topic of current research. The future trend in this domain is to integrate the communication, navigation, and remote sensing functions to build a satellite–ground integration network. One of the advantages is that it will greatly benefit from making up for the shortage of traditional terrestrial cellular network coverage and the precision, convergence time, and signal strength that users receive from high-orbit navigation satellites. However, developing such a versatile, sophisticated, and intelligent platform is still challenging. The main issue arises when the low earth orbit satellites, work as transponders and communicate with high orbit navigation satellites and terminal receivers on the ground in a co-frequency co-time unidirectional transponder (CCUT) leading to severe self-interference. what’s worse, the power augmentation signal sent to the GNSS receiver is far stronger than the navigation augmentation signal received from a high-orbit satellite, which leads to receiver saturation. In this paper, a self-interference cancellation algorithm has been realized on an embedded platform. Experimental results show that the cancellation depth at the navigation frequency band with 10.23MHz bandwidth was 30dB.