Robust algorithm for high-dynamic and low-signal-tonoise ratio signal reception in deep space communications

In deep space communications, the received signals are always highly dynamic and very weak, which makes it quite challenging to achieve reliable data reception. To tackle these problems, a robust algorithm which joins tracking and code-aided synchronisation is proposed in this study. The frequency lock loop-assisted phase lock loop is used as the tracking loop, which integrates the characteristics of both outstanding dynamic performance and precise measurement. The code-aided synchronisation is adopted as the demodulation and decoding loop, which utilises the relationship among the coded symbols to assist signal demodulation under the low signal-to-noise ratio condition. It is worth pointing out that the power tradeoff between the main carrier and subcarrier signals which operate in the two loops mentioned above is also optimised to minimise the total transmitting power. Simulation results showed that the proposed scheme with code rate 1/5 low-density parity-check codes could almost eliminate the effect of these factors, with the excellent performance, which closely approximates the ideal decoder in additive white Gaussian noise channel.