A Spectral Efficiency Enhancement for Chirp Spread Spectrum Downlink Communications

The objective of the paper is to propose a transmitter/receiver system that increases the spectral efficiency in the context of CSS-type downlink communications. For this purpose, we propose to transmit simultaneously on the same time/frequency resources signals intended for several receivers. By controlling the level of interference between the different users and the properties of quasi-orthogonality between up and down chirps, we show that each receiver can correctly demodulate the symbols intended for it.