On random CDMA with constant envelope

This paper studies the design of random code-division multiple-access (CDMA) with continuous-time constant envelope. The proposed scheme is compatible with linear CDMA and allows for standard methods of linear multiuser detection while avoiding phase jumps at all times. The proposed algorithm finds a set of spreading waveforms with approximately rectangular power spectral density and stop-band attenuation of more than 60 dB at exactly constant envelope. Alternatively, the algorithm can provide perfect stop-band attenuation at a peak-to-average power ratio of 0.04 dB at spreading factor 512.