Performance of the Space-Time Block Coded DS-CDMA Uplink Employing Soft-Output ACO-Aided Multiuser Space-Time Detection and Iterative Decoding

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Description/Abstract

Abstract—In this treatise we propose a three-stage twin-transmit-antenna assisted MultiUser (MU) Direct Sequence Code-Division Mulitple Access (DS-CDMA) system employing both a Unitary Rate Code (URC) and a Recursive Systematic Code (RSC) to carry out iterative turbo detection. A Space-Time Block Code (STBC) is used to provide second-order diversity gain in conjunction with a novel soft-output (SO) ant-colony optimization (ACO) based space-time multiuser detection (ST/MUD) algorithm, which is capable of carrying out STBC decoding, while mitigating the MultiUser Interference (MUI) and generating the Log-Likelihood Ratios (LLR) for facilitating the iterative exchange of extrinsic informa- tion between the URC and RSC decoders of each user. With aid of the above mentioned state-of-the-art techniques, the proposed system becomes capable of approaching the performance of the single-user system within about 0.5dB, when K = 32 users are supported with the aid of 31-chip Gold-codes.