Turbo-Fsk, a Physical Layer for LPWA: Synchronization and Channel Estimation.

Turbo Frequency Shift Keying (Turbo-FSK) has been considered as a promising physical layer for low power wide area applications. Its constant envelope at the transmitter combined with performance close to the Shannon's limit enable to achieve a high energy efficiency. However, results published so far in the literature for this waveform have assumed perfect synchronization and channel estimation. This paper, presents a synchronization and channel estimation approach based on a specifically built preamble and adapted to the performance of the new modulation. Simulations have been performed for both time and frequency synchronization as well as channel estimation. Less than 1 dB degradation in comparison to perfect detection is achieved for the most severe types of channels.