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1. (WO2018137782) DIGITAL PRE-DISTORTION FOR COMPLEX MODULATOR BASED-IMDD SYSTEM

Pub. No.:    WO/2018/137782    International Application No.:    PCT/EP2017/051928
Publication Date: Fri Aug 03 01:59:59 CEST 2018 International Filing Date: Tue Jan 31 00:59:59 CET 2017
IPC: H04B 10/40
H04B 10/58
Applicants: HUAWEI TECHNOLOGIES CO., LTD.
ZHANG, Qiang
Inventors: ZHANG, Qiang
Title: DIGITAL PRE-DISTORTION FOR COMPLEX MODULATOR BASED-IMDD SYSTEM
Abstract:
The present invention relates to a digital signal processing module in a transmitter of an optical transceiver. The digital signal processing module performs a bias-related linear transform in order to align, in a vector plane, the vector of an optical carrier signal with the vector of a modulated optical signal that is modulated by a modulator implemented inside the transmitter, and also performs a digital pre-distortion in order to compensate for the nonlinearity of the modulator. The digital pre-distortion method mainly consists in converting a target signal into a pre-distorted signal by subtracting a signal proportional to the distortion signal from the target signal. The non-orthogonality of the modulator is mitigated by an appropriate bias-related linear transform that is selected as to obtain the best quality performance using a scan method or as to obtain a maximum value of cross-correlation using a pilot tone method.