Multi-rate multi-code CDMA using FWT for mobile and personal communications

We simulate a flexible direct sequence-code division multiple access (DS-CDMA) multi-rate system that uses a serial variable processing gain PN modulation together with multi-code modulation. The advantage of serial transmission is that only one waveform is transmitted at a given time resulting in a constant envelope transmission. Multi-code modulation provides a reliable high-speed data communications by using the fast Walsh transform (FWT). The performance of the proposed system is evaluated using computer simulation of different groups of data rates through a frequency selective Rayleigh multipath fading channel.