Multi-Dimensional Codebooks for Multiple Access Schemes
The sparse code multiple access (SCMA) scheme directly maps the incoming bits of several sources (users/streams) to complex multi-dimensional codewords selected from a specific predefined sparse codebook set. The codewords of all sources are then superimposed and exchanged. The shaping gain of the m...
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| Autores principales: | , , |
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| Formato: | Capítulo de libro |
| Lenguaje: | inglés |
| Publicado: |
IntechOpen
2023
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| Materias: | |
| Acceso en línea: | https://www.intechopen.com/chapters/86135 |
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| Sumario: | The sparse code multiple access (SCMA) scheme directly maps the incoming bits of several sources (users/streams) to complex multi-dimensional codewords selected from a specific predefined sparse codebook set. The codewords of all sources are then superimposed and exchanged. The shaping gain of the multi-dimensional constellation of SCMA leads to a better system performance. The decoder’s objective will be to separate the superimposed sparse codewords. Most existing works on SCMA decoders employ message passing algorithm (MPA) or one of its variations, or a combination of MPA and other methods. The system architecture is highlighted and its basic principles are presented. Then, an overview of main multi-dimensional constellations for SCMA systems will be provided. Afterwards, we will focus on how the SCMA codebooks are decoded and how their performance is evaluated and compared. |
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| ISBN: | 978-1-83768-502-8 |
| DOI: | 10.5772/intechopen.110032 |