Abstract
We study a multiple access encoding/decoding algorithm based on iterative (turbo) decoding. The algorithm is suitable for both synchronous and asynchronous systems. The quasi-orthogonal pseudo-noise sequences of the DS-SSMA system are replaced by independent channel codes constructed by combining convolutional codes and random interleavers. The interference is rebuilt using soft output information. The results show that the iterative joint decoder is able to completely eliminate the co-channel interference. The performance of the multiple access system tends practically to that of a single user system.
Résumé
L’article étudie un algorithme de codage/décodage pour l’accès multiple par étalement de spectre basé sur un décodage itératif (turbo). L’algorithme est applicable aux systèmes synchrones et asynchrones. Les séquences pseudo-aléatoires quasi-orthogonales du système d’accès multiple par étalement de spectre à séquences directes sont remplacées par celles de codes correcteurs d’erreurs indépendants construits par combinaison de codes convolutifs et d’entrelaceurs aléatoires. Le brouillage est reconstruit au niveau du décodeur à l’aide d’une information de sortie souple. Les résultats des simulations montrent que le décodeur itératif conjoint est capable d’éliminer complètement le brouillage multiutili-sateur. Les performances du système d’accès multiple proposé tendent pratiquement vers celles d’un système monoutilisateur.
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Brunel, L., Boutros, J. Code division multiple access based on independent codes and turbo decoding. Ann. Télécommun. 54, 401–410 (1999). https://doi.org/10.1007/BF02997762
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DOI: https://doi.org/10.1007/BF02997762
Key words
- Code division multiple access
- Direct sequence spectrum
- Error correcting code
- Decoding
- Convolutional code
- Interleaving
- Iteration
- Signal interference
- Channel capacity
- Numerical simulation
- System performance