The invention concerns a CDMA system, including a transmitter and receiver, for use in e.g. a digital wireless communications system and in particular to a method of and apparatus for mapping and demapping CDMA signals. The CDMA system comprises a transmitter and a receiver. The transmitter includes an encoder and a bit interleaver for processing said CDMA signal to be transmitted, a mapper connected in series with the encoder and bit interleaver and means for transmitting said processed CDMA signal. The receiver comprises means for receiving said transmitted CDMA signal, a bit deinterleaver and a decoder for processing said received CDMA signal and a demapper connected in series with the bit deinterleaver and decoder. Iterative demapping may be performed in the receiver by passing back the output of the decoder to the demapper. A corresponding method is also disclosed.