MMSE interference suppression for coded multicarrier DS-CDMA in the presence of intermodulation

This paper presents a coded multicarrier (MC) DS-CDMA system which, by the use of a linear convolutional code (CC) and minimum mean-squared error (MMSE) receiver, achieves frequency diversity instead of path diversity as in a conventional single carrier RAKE DS-CDMA, and has the ability to partially compensate for the distortion introduced by a nonlinear amplifier at the transmitter. A frequency selective Rayleigh fading channel is decomposed into M frequency non-selective channels, based on the channel coherence bandwidth. A rate 1/M convolutional code, after being interleaved, is used to modulate M different DS-CDMA waveforms. The new system is shown to effectively suppress multiple access interference in the presence of intermodulation distortion.