Open Access10.20381/RUOR-12320
Iterative coded multiuser detection using LDPC codes
Danfeng Xu,Claude D'Amours +1 more
- 26 May 2008
- pp 143-148
TL;DR: Three iterative soft-input soft-output (SISO) multiuser detectors are presented and it is shown that the iterative MUD and decoding can achieve a substantial performance gain over separate detection and decoding.
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Abstract: In this paper, the performance of low-density paritycheck (LDPC) coded multiuser CDMA system is investigated. Multiuser detection (MUD) and LDPC decoding are combined to improve the performance. The soft output of the LDPC decoder is fed back to the multiuser detector to improve the detection. This leads to detection variables that have a reduced multiple access interference (MAI) component. These decision variables are then returned to the decoder. Due to the soft information exchange, both the multiuser detector and the LDPC decoder outputs can be continuously improved. Therefore, the iterative MUD and decoding can achieve a substantial performance gain over separate detection and decoding. Three iterative soft-input soft-output (SISO) multiuser detectors are presented. They are soft interference cancellation detector, soft-input soft-output de-correlating detector and SISO MMSE detector. The performance comparison is also provided.
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References
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Digital Communications
John G. Proakis
- 01 Jan 1983
TL;DR: This month's guest columnist, Steve Bible, N7HPR, is completing a master’s degree in computer science at the Naval Postgraduate School in Monterey, California, and his research area closely follows his interest in amateur radio.
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Low-Density Parity-Check Codes
Robert G. Gallager
- 01 Jan 1963
TL;DR: A simple but nonoptimum decoding scheme operating directly from the channel a posteriori probabilities is described and the probability of error using this decoder on a binary symmetric channel is shown to decrease at least exponentially with a root of the block length.
Good error-correcting codes based on very sparse matrices
David J. C. MacKay
- 29 Jun 1997
TL;DR: It is proved that sequences of codes exist which, when optimally decoded, achieve information rates up to the Shannon limit, and experimental results for binary-symmetric channels and Gaussian channels demonstrate that practical performance substantially better than that of standard convolutional and concatenated codes can be achieved.
Design of capacity-approaching irregular low-density parity-check codes
TL;DR: This work designs low-density parity-check codes that perform at rates extremely close to the Shannon capacity and proves a stability condition which implies an upper bound on the fraction of errors that a belief-propagation decoder can correct when applied to a code induced from a bipartite graph with a given degree distribution.
The capacity of low-density parity-check codes under message-passing decoding
TL;DR: The results are based on the observation that the concentration of the performance of the decoder around its average performance, as observed by Luby et al. in the case of a binary-symmetric channel and a binary message-passing algorithm, is a general phenomenon.