Method and apparatus for monitoring in-line signal quality and system

An apparatus for monitoring in-line signal quality, configured in a transmitting end of a multicarrier optical communication system based on discrete multi-tone modulation, the apparatus comprising:

• a controlling unit configured to control a transmitter to transmit training sequences in subcarriers in a transmission initialization period;
• a configuring unit configured to acquire bit allocation and power allocation of the subcarriers and a position of a pilot subcarrier, configure the subcarriers, and map one of data to be transmitted and a training sequence to corresponding subcarriers;
• and
• a first processing unit configured to, when the transmitter receives a pilot-based SNR (signal to noise ratio) measurement request regarding a data subcarrier, exchange power allocation and bit allocation of the data subcarrier and the pilot subcarrier, adjust a data mapping relationship of the data subcarrier to the pilot subcarrier, adjust a mapping relationship of the training sequence of the pilot subcarrier to the data subcarrier, and synchronize with a receiver in a receiving end.

A multicarrier optical communication system based on discrete multi-tone modulation, comprising a transmitter and a receiver, and further comprising a transmitting end controller and a receiving end controller;

• wherein,
• the receiving end controller is configured to:
• according to SNRs (signal to noise ratios) of subcarriers obtained in a transmission initialization period, set a subcarrier with a highest SNR to be a pilot subcarrier and other subcarriers to be data subcarriers;
• determine bit allocation and power allocation of the pilot subcarrier and bit allocation and power allocation of the data subcarriers;
• set data-decision-based SNR measurement thresholds for the data subcarriers according to the bit allocation of the data subcarriers;
• and
• compare the SNRs of the data subcarriers obtained through data-decision-based SNR measurement in a transmission period with the SNR measurement thresholds of the data subcarriers, and when an SNR of a data subcarrier is less than a corresponding SNR measurement threshold, trigger pilot-based SNR measurement of the data subcarrier;
• and the transmitting end controller is configured to:
• control a transmitter to transmit training sequences in subcarriers in the transmission initialization period;
• acquire bit allocation and power allocation of the subcarriers and a position of a pilot subcarrier, configure the subcarriers, and map one of data to be transmitted and a training sequence to corresponding subcarriers;
• and
• when the transmitter receives a pilot-based SNR measurement request regarding a data subcarrier, exchange power allocation and bit allocation of the data subcarrier and the pilot subcarrier, adjust a data mapping relationship of the data subcarrier to the pilot subcarrier, adjust a mapping relationship of the training sequence of the pilot subcarrier to the data subcarrier, and synchronize with the receiver in the receiving end.