Deep-Unfolded Sparse CDMA: Multiuser Detector and Sparse Signature Design

Sparse code division multiple access (SCDMA) is a promising non-orthogonal multiple access technique for future wireless communications. In SCDMA, transmitted symbols from multiple users are coded by their own sparse signature sequences, and a base station attempts to detect those symbols using the...

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Main Authors: Satoshi Takabe, Yuki Yamauchi, Tadashi Wadayama
Format: Article
Language:English
Published: IEEE 2021-01-01
Series:IEEE Access
Subjects:
Online Access:https://ieeexplore.ieee.org/document/9373341/
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author Satoshi Takabe
Yuki Yamauchi
Tadashi Wadayama
author_facet Satoshi Takabe
Yuki Yamauchi
Tadashi Wadayama
author_sort Satoshi Takabe
collection DOAJ
description Sparse code division multiple access (SCDMA) is a promising non-orthogonal multiple access technique for future wireless communications. In SCDMA, transmitted symbols from multiple users are coded by their own sparse signature sequences, and a base station attempts to detect those symbols using the signature sequences. In this paper, we present a new deep-unfolded multiuser detector called a complex sparse trainable projected gradient (C-STPG) detector for SCDMA systems. Deep unfolding is a deep learning method that tunes trainable parameters in iterative algorithms using supervised data and deep learning techniques. The proposed detector provides a much superior detection performance over that of the LMMSE detector. Other advantages of the proposed detector include a low computational complexity in execution and a low training cost owing to the small number of trainable parameters. In addition, we propose a novel joint learning strategy called gradual sparsification for designing sparse signature sequences based on deep unfolding. This method is computationally efficient in optimizing a set of sparse signature sequences. Numerical results show that the gradual sparsification successfully yields sparse signature sequences with a smaller symbol error rate than those of randomly designed sparse signature sequences.
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spelling doaj.art-143651b8898f4f1493ba91ac87c450c92022-12-21T17:25:29ZengIEEEIEEE Access2169-35362021-01-019400274003810.1109/ACCESS.2021.30645589373341Deep-Unfolded Sparse CDMA: Multiuser Detector and Sparse Signature DesignSatoshi Takabe0https://orcid.org/0000-0002-5755-2231Yuki Yamauchi1Tadashi Wadayama2https://orcid.org/0000-0003-4391-4294Nagoya Institute of Technology, Nagoya, JapanNagoya Institute of Technology, Nagoya, JapanNagoya Institute of Technology, Nagoya, JapanSparse code division multiple access (SCDMA) is a promising non-orthogonal multiple access technique for future wireless communications. In SCDMA, transmitted symbols from multiple users are coded by their own sparse signature sequences, and a base station attempts to detect those symbols using the signature sequences. In this paper, we present a new deep-unfolded multiuser detector called a complex sparse trainable projected gradient (C-STPG) detector for SCDMA systems. Deep unfolding is a deep learning method that tunes trainable parameters in iterative algorithms using supervised data and deep learning techniques. The proposed detector provides a much superior detection performance over that of the LMMSE detector. Other advantages of the proposed detector include a low computational complexity in execution and a low training cost owing to the small number of trainable parameters. In addition, we propose a novel joint learning strategy called gradual sparsification for designing sparse signature sequences based on deep unfolding. This method is computationally efficient in optimizing a set of sparse signature sequences. Numerical results show that the gradual sparsification successfully yields sparse signature sequences with a smaller symbol error rate than those of randomly designed sparse signature sequences.https://ieeexplore.ieee.org/document/9373341/SCDMAdeep learningdeep unfoldingmultiuser detectorsignature design
spellingShingle Satoshi Takabe
Yuki Yamauchi
Tadashi Wadayama
Deep-Unfolded Sparse CDMA: Multiuser Detector and Sparse Signature Design
IEEE Access
SCDMA
deep learning
deep unfolding
multiuser detector
signature design
title Deep-Unfolded Sparse CDMA: Multiuser Detector and Sparse Signature Design
title_full Deep-Unfolded Sparse CDMA: Multiuser Detector and Sparse Signature Design
title_fullStr Deep-Unfolded Sparse CDMA: Multiuser Detector and Sparse Signature Design
title_full_unstemmed Deep-Unfolded Sparse CDMA: Multiuser Detector and Sparse Signature Design
title_short Deep-Unfolded Sparse CDMA: Multiuser Detector and Sparse Signature Design
title_sort deep unfolded sparse cdma multiuser detector and sparse signature design
topic SCDMA
deep learning
deep unfolding
multiuser detector
signature design
url https://ieeexplore.ieee.org/document/9373341/
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AT yukiyamauchi deepunfoldedsparsecdmamultiuserdetectorandsparsesignaturedesign
AT tadashiwadayama deepunfoldedsparsecdmamultiuserdetectorandsparsesignaturedesign