Single-carrier-and-multi-carrier-based hybrid transmission system

Abstract

The invention provides an optical communication system, which has transmission performance higher than that of a single modulation way. Two modulation formats are multiplexed onto an optical carrier in a polarization multiplexing way to realize the hybrid transmission of the two different modulation formats. A polarization beam splitter splits laser into two paths, wherein one path adopts a single-carrier light modulation technology, and the other path adopts an orthogonal frequency division multiplexing (OFDM) light modulation technology. A polarization light combiner performs polarization multiplexing on modulated signals to finish a transmitter function. The peak-to-average ratio of light spectrums of the hybrid modulated signals is between that of single-carrier modulated signals and that of OFDM modulated signals. In the invention, a receiver selects an advantaged modulation format from the two modulation formats for the key signal processing of electrical dispersion compensation and digital phase compensation, thereby realizing the advantage complementation of the two modulation formats and improving overall system performance.

Description

technical field [0001] The invention belongs to the technical field of communication, and in particular relates to digital signal processing in a high-speed optical fiber transmission system. Background technique [0002] There are already many different modulation formats in optical fiber communication systems, but it is not easy to choose a modulation format suitable for high-speed optical communication. The main reason is that different modulation formats have different characteristics, such as different spectral efficiency, cost and computational complexity. . At present, the receiving end of the high-speed optical transmission system uses a digital signal processor (DSP) to compensate the signal distortion caused by the optical fiber link, so as to increase the optical transmission rate has become an inevitable development direction. At present, the DSP at the receiving end in the high-speed optical transmission system mainly performs the following processing before de...

AI Technical Summary

Problems solved by technology

However, a prominent problem of optical OFDM is that the peak-to-average ratio of its time-domain signal is very high, that is, its signal power fluctuates greatly.

This problem not only poses challenges to the design and manufacture of transmitters and receivers, but also causes the corresponding optical signals to cause stronger nonlinear effects of optical fibers during optical fiber transmission, thereby reducing the quality of received optical signals.

Another problem with optical OFDM is that it is sensitive to phase noise, including the phase noise of the laser

Multi-carrier systems use low-rate sub-carriers, and their tolerance to laser phase noise is relatively small. Therefore, optical OFDM systems need to use lasers with narrow linewidths, and the cost is high

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