FTN Signaling In the Saturation Regime
Résumé
Faster-than-Nyquist (FTN) signaling is investigated in future satellite communication standardization for an improved spectral efficiency considering the increasingly constrained resource. Previous studies showed that FTN lower modulation orders compressed in time-domain could reach the spectral efficiency of uncompressed higher modulation orders. The FTN gain in terms of transmission rate is obtained at the price of a turbo-equalization at the receiver, increasing the complexity. The increased capacity in DVB-S2X’s transmissions is due to innovations increasing the fluctuation of the complex envelop of the transmitted signal. Since the satellite’s payload introduces higher non-linear distortions with increased fluctuations, the growing receiver’s complexity is unavoidable. However, in this non linear regime, the complexity of the FTN receiver is not this detrimental compared with those of a classical Nyquist receiver. For a similar spectral efficiency, its lower Peak to Average Power Ratio (PAPR), making the non-linearities treatment easier, makes this innovation suitable for future satellite communications, especially when the payload is operated in the saturation regime. In this paper, we show that compression offers a gain between 10 and 20 in terms of spectral efficiency when compared to Nyquist signaling, both equalized thanks to the MAP symbol detection based on the Volterra series model of non-linearities.
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