International audienceAs the Internet-of-Things (IoT) has expanded, multiple solutions have attempted to address the issues of the Low Power Wide Area (LPWA) networks physical layer. In a previous work, we proposed the Turbo-FSK, a constant envelope modulation with orthogonal alphabet that allows the receiver to operate at very low levels of power (high sensitivity performance) and very low levels of energy per bit E b. The scheme was demonstrated to approach Shannon's limit as close as 0.29dB. However, the scheme lacks of flexibility in terms of spectral efficiency (always lower than 0.1 bits/s/Hz), especially compared to the recently standardized Narrow-Band IoT (NB-IoT) solution. In this work, we propose an evolution of the initial schem...