A phase noise compensation method and system for co-ofdm system based on rf pilot frequency

Abstract

The invention discloses an RF pilot based CO-OFDM system phase noise compensation method and system, and belongs to the technical field of optoelectronic communication. The system disclosed by the invention comprises a coarse compensation module and a fine compensation module, wherein a receiving end extracts the RF pilot by using a digital low-pass filter after coherent demodulation and analog-to-digital conversion; after being compared with a sending end and conjugated, the pilot is multiplied by a signal, so that coarse phase compensation is realized; the coarse compensation signal is converted to the frequency domain through FFT, so that constellation prejudgement is carried out; time domain partition on a prejudgement result and a coarse compensation result is carried out at the sametime; and, fine phase correction on the coarse compensation result of each partition is carried out by taking the prejudgement result as reference. The invention further discloses the RF pilot based CO-OFDM system phase noise compensation method. Compared with the existing subcarrier pilot based phase noise compensation scheme, the RF pilot based CO-OFDM system phase noise compensation method hasbetter ICI compensation performance; and in addition, due to fine compensation based on prejudgement and partition correction, the nonlinear phases shift resisting capability of the RF pilot is further improved.

Description

technical field [0001] The invention belongs to the technical field of optoelectronic communication, and more specifically relates to a CO-OFDM system phase noise compensation method based on RF pilot. Background technique [0002] The subcarriers in the optical communication CO-OFDM system are susceptible to phase-correlated noise interference, which causes the rotation and divergence of the receiving constellation diagram. The phase noise mainly comes from the laser linewidth and link nonlinearity. Due to the long symbol length and high peak-to-average power ratio of the CO-OFDM system, its transmission performance is more susceptible to phase noise degradation. How to efficiently monitor and compensate phase noise is a key issue in CO-OFDM systems. [0003] Existing schemes based on subcarrier pilots obtain the distortion of constellation symbols through subcarriers loaded in the frequency domain, but can only estimate the average phase shift error (CPE) in the entire OF...

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Problems solved by technology

[0003] Existing schemes based on subcarrier pilots obtain the distortion of constellation symbols through subcarriers loaded in the frequency domain, but can only estimate the average phase shift error (CPE) in the entire OFDM symbol period, which is difficult for intercarrier interference that changes rapidly over time. (ICI) noise is powerless; while the RF pilot-based scheme obtains instantaneous phase distortion information through the synchronous extraction of RF pilot and sampling, but its spectral efficiency is not high, the device cost is large, and the compensation performance under comprehensive conditions is often limited

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