this project is based on using chirp spread spectrum modulation to modulate users signals and to use NOMA as multople access scheme lora_tx lora_rx pilot as apackage to modulate and demodulate lora as explained in lora tx&Rx.pdf noma_en.m is the code for noma system dm_css.m and respective pdf is another type of css A Downlink NOMA for Chirp Spread Spectrum Communications is the system we want to achieve using underwater acoustic channel Frequency Shift Chirp Spread Spectrum Communications with Index Modulation has its latex files 2102.04642v2