Multi-Satellite Collaborative Signal Acquisition for Internet of Remote Things

This paper presents a novel non-coherent multi-satellite weak signal acquisition scheme by aggregating the observations at multiple LEO satellites. Existing aggregation schemes rely on exhaustive search over grids on Earth surface to compensate for the differences in the delay and the Doppler frequency shift experienced at different satellites, which have high computational complexity due to the wide coverage of LEO satellites. Motivated by this observation, we propose to directly work with satellites' Time-frequency (TF) grid and facilitate efficient delay and Doppler compensation by gradually narrowing down the search space over each satellite's TF grid with multi-satellites observations. Our scheme employs geometric search space reduction scheme to reduce the search space for possible Doppler frequency shift and utilizes hierarchical geometric correlation peak matching to eliminate fake correlation peaks based on multi-satellite observations. Through extensive performance evaluation, we demonstrate that, in comparison with existing schemes, our proposed multi-satellite signal acquisition scheme can achieves significantly better acquisition performance with a much lower computational complexity.