EXIT Chart Based Joint Code-Rate and Spreading-Factor Optimisation of Single-Carrier Interleave Division Multiple Access

Abstract—In this paper, we consider the joint code-rate and spreading-factor optimisation of turbo-style iterative joint detection and decoding assisted single-carrier interleave division multiple access (SC-IDMA) systems using different-rate convolutional codes and Extrinsic Information Transfer (EXIT) charts, when communicating over Additive White Gaussian Noise (AWGN) channels. More explicitly, we study the extrinsic information exchange between two serial concatenated components and maximise the number of users supported by the SC-IDMA system under the constraint of a fixed bandwidth expansion factor, while maintaining a predefined Bit Error Ratio (BER) versus Eb/N0 performance. We found that an optimum coderate and spreading-factor combination can be found for the SC-IDMA system at low Eb/N0 values, where maintaining a low BER inevitably requires the employment of channel coding. By contrast, at high Eb/N0 the system performs best, when no channel coding is used, i.e. DS-spreading is the only means of bandwidth expansion

Multi-carrier CDMA using convolutional coding and interference cancellation

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EXIT-charts-aided hybrid multiuser detector for multicarrier interleave-division multiple access

A generically applicable hybrid multiuser detector (MUD) concept is proposed by appropriately activating different MUDs in consecutive turbo iterations based on the mutual information (MI) gain. It is demonstrated that the proposed hybrid MUD is capable of approaching the optimal Bayesian MUD's performance despite its reduced complexity, which is at a modestly increased complexity in comparison with that of the suboptimum soft interference cancellation (SoIC) MU

Turbo Multiuser Detection Architectures

The discovery of Turbo Codes in 1996 by Berrou et. al. proved to be a huge boost for the research of channel coding. The Turbo Principle behind turbo codes was found to be applicable in other areas. One of these areas is Multiuser Detection. In this thesis, Turbo Multiuser Detection is investigated in order to answer two main questions. The questions concern the performance gain that is obtained when turbo multiuser detection is used instead of non-turbo multiuser detection and the convergence behavior of turbo multiuser detection. The performance gain is determined by comparing the bit-error-rate (BER) chart of a turbo multiuser detection architecture with the BER chart of a non-turbo multiuser detector. It was found that turbo multiuser detection results in a dramatical performance gain when Eb/N0 > 3 dB and more than one iteration is performed. The convergence behavior of turbo multiuser detection is analyzed with the help of EXIT charts. EXIT charts are recently proposed by S. ten Brink as a tool to analyze the convergence behavior of turbo architectures. EXIT charts are discussed in this thesis. An EXIT chart of a turbo multiuser detection architecture is created. From this chart, the minimum number of iterations to obtain the lowest BER possible are found.\ud EXIT charts are also used to analyze the difference of iterating aposteriori and extrinsic information in a turbo architecture. The analysis shows that EXIT charts of a-posteriori information give results, which contradict the results of simulations on turbo architectures

Turbo Decoding and Detection for Wireless Applications

A historical perspective of turbo coding and turbo transceivers inspired by the generic turbo principles is provided, as it evolved from Shannon’s visionary predictions. More specifically, we commence by discussing the turbo principles, which have been shown to be capable of performing close to Shannon’s capacity limit. We continue by reviewing the classic maximum a posteriori probability decoder. These discussions are followed by studying the effect of a range of system parameters in a systematic fashion, in order to gauge their performance ramifications. In the second part of this treatise, we focus our attention on the family of iterative receivers designed for wireless communication systems, which were partly inspired by the invention of turbo codes. More specifically, the family of iteratively detected joint coding and modulation schemes, turbo equalization, concatenated spacetime and channel coding arrangements, as well as multi-user detection and three-stage multimedia systems are highlighted