Joint despreading and iterative decoding in DS-CDMA system with serially concatenated turbo code and Walsh code

A DS-CDMA system with integrated ECC (error control coding) technique is presented. The encoder is a serial concatenation of a turbo code and a Walsh orthogonal code. An iterative algorithm for MAP decoding is implemented in the receiver. Decoding and despreading are unified through a joint iterative process in terms of exchanging soft information among receiver components. Compared to similar DS-CDMA systems, in the region of signal-to-noise ratios of interest, the proposed system shows excellent performance even at low input block size. This approach suggests a convenient scheme that can be used to implement FEC (forward error correction) in a personal communication system, for applications intolerable to delay.