Turbo Multiuser Detection in CDMA with Turbo Coding
In this section we discuss turbo multiuser detection for CDMA
systems employing turbo codes. Parallel concatenated codes, called turbo codes, constitute the most important breakthrough
in coding of the 1990s [177]. Since these powerful codes can
achieve near-Shannon-limit error correction performance with relatively low
complexity, they have been adopted as an optional coding technique standardized
in third-generation (3G) CDMA systems [201]. We first give a brief
introduction to turbo codes and describe the turbo decoding algorithm for
computing the extrinsic information. We then compare the performance of a turbo
multiuser receiver with that of a conventional RAKE receiver followed by turbo
decoding, in a turbo-coded CDMA system with mulitpath fading channels. The
material discussed in this section was developed in [256, 257].
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