说明：   The main aim of our project is to simulate CDMA modem using DS-SS (Direct sequence spread spectrum) in MATLAB. Spread spectrum is basically type of modulation that spreads data transmission across available frequency band, in excess of minimum bandwidth available. We will be generating code by multiplying with pseudo random code in order to generate spread spectrum, transmitting it over a common frequency band and de-spreading the signal using same pseudo random code at the receiver. Also our aim is to simulate the de-spreading of the received CDMA signal in the presence of AWGN .