A frequency-offset estimation algorithm combines code and time features for the remote reception of a weak satellite signal

Abstract

Remote control technology has greatly expanded the intelligence and automation of industry. Satellite signals are important to keep in contact with the facilities and devices in remote areas. However, satellite channels suffer from multi-scale attenuation to achieve reliable communications, which cannot provide sufficient accuracy and suitable complexity for the frequency-offset estimation of a weak signal. Therefore, this paper focused on a frequency-offset estimation method for a weak signal from a distant, poor satellite channel. First, we built a model of a distant satellite channel with mirror power reflection, considering large fading and multi-path fading simultaneously. Second, we described M-Walsh pilots and a signal vector matrix as they relate to satellite signals. Initially, we analysed the performance of different frequency-offset estimation methods in the satellite environment as opposed to the ground environment. We proposed compact M-Walsh pilots locking correlation to improve the estimation accuracy, which enhanced the frequency tracking. We further proposed equivalent weighting estimation allocation to help improve the balance of accuracy and complexity in the algorithm. Simulations and tests demonstrated that the new algorithm enhanced the root-mean-square-error frequency-offset estimate by 36.2% and the bit-to-error rate) performance by 29.5%.