Iterative multiuser interference reduction: Turbo CDMA

We view the asynchronous random code-division multiple-access (CDMA) channe l as a time-varying convolutional code. We study the case where the users e ncode their data, and, therefore, the single user transmitters and the CDMA channel appear as the concatenation of two coding systems. At the receiver we employ serial Turbo decoding strategies. Unlike conventional Turbo code s where both the inner and outer code may be selected, in our case, the inn er code is due to the CDMA channel which we assume to be random. Neverthele ss, the decoding system resembles-the decoder of a serial Turbo code and si ngle-user performance is obtained even for numbers of users approaching the spreading code length.