Preamble detection in NB-IoT via Satellite: A Wavelet based approach

Satellite Communications systems are a promising solution to extend and support terrestrial networks in un- or under-served areas. In Release 17, 3GPP initiated a Study Item for IoT over Non-Terrestrial Networks (NTN) to assess and adapt the NB-IoT air interface to the NTN characteristics. One of the main objective of the study is the evaluation of the Random Ac-cess procedure and the estimation of the up-link synchronization parameters at the satellite. In this context, it is essential that the detection algorithms of the NB-IoT preamble, at the receiver, satisfy the user detection requirements as well as the timing synchronization accuracy. This is not a trivial task, especially in satellite channels where the carrier frequency offset (CFO) is more severe than that of terrestrial links. In order to cope with this problem, we propose a new algorithm based on a non-decimated dyadic wavelet transform. This method is able to detect the incoming preambles and to estimate their time of arrival, without having to compensate the CFO first. The performance of the proposed algorithm is compared with a classical estimation approach based on the Fast Fourier Transform, substantiating the significant advantage obtained in the considered NTN scenarios.