Abstract
WhenOFDM or multitone modulation is used, the dispersiveness of the channel is usually circumvented by means of the technique of guard time. As an alternative it is possible not to use a guard time but design receivers able to equalize theisi andici. In the present paper we show how to design fractionally spaced linear or decision-feedback Mimo equalizers for multitone systems without guard time. Full complexity and reduced complexity solutions are investigated. The design is made for anmmse criterion and the steady-state performance is analysed. It is shown that Mimo equalization outperforms the technique of guard time, that fractionally spaced devices are very effective and the complexity reduction produces a performance degradation which is negligible compared to full complexity fractionally spaced devices, especially when the processing rate is larger than the symbol rate.
Résumé
Quand les modulateursofdm ou multiporteuses sont utilisés, la dispersion du canal est généralement combattue par ľintroduction ďun temps de garde. Une autre approche consiste à concevoir des récepteurs capables ďégaliser les interférences entre symboles et entre canaux. Dans cet article, on montre comment calculer des égaliseurs à espacement fractionnaire et à décision réfléchie. Des solutions avec complexité pleine et réduite sont étudiées. Les performances en régime établi sont analysées pour un calcul basé sur le critère des moindres carrés. On montre que ľégalisation Mimomultisorties-multientrées est meilleure que la technique du temps de garde, que ľespacement fractionnaire est très efficace et que la réduction de complexité apporte une dégradation négligeable des performances, notamment quand la cadence de traitement est plus grande que la cadence des symboles.
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This author would like to thank the Belgian nsf for its financial support.
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Vandendorpe, L. Fractionally spaced linear and DF Mimo equalizers for multitone systems without guard time. Ann. Télécommun. 52, 21–30 (1997). https://doi.org/10.1007/BF03001046
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DOI: https://doi.org/10.1007/BF03001046
Key words
- Equalizer
- Linear estimation
- Decision feedback
- Frequency division multiplexing
- Orthogonal signal
- Intersymbol interference
- Signal interference
- Multipath propagation
- Complexity
- Fractional number