System, device and modulation/demodulation method suitable for OFDMA-OPN (Orthogonal Frequency Division Multiple Access Optical Passive Network)

Abstract

The invention relates to a system, device and modulation / demodulation method suitable for OFDMA-OPN. The system comprises an OLT downlink transmitter and an ONU downlink receiver. The OLT downlink transmitter modulates two paths of signals input by an electric domain to obtain two paths of OFDMA baseband signals, each path of OFDMA baseband signals and signals thereof after phase shift are loaded on one optical carrier wave which is orthogonal to the polarization direction to obtain one path of single sideband O-OFDMA signals, the two paths of single sideband O-OFDMA signals are combined into one path of O-OFDMA multiplexing signals, and the path of O-OFDMA multiplexing signals is sent to fibers for transmission. The ONU downlink receiver divides the one path of O-OFDMA multiplexing signals sent from the fibers into two paths of O-OFDMA signals orthogonal to the polarization direction, photoelectric detection and modulation are implemented on the O-OFDMA signals, and two paths of signals are output to the electric domain. Thus, cross polarization crosstalk of signals can be inhibited.

Description

technical field [0001] The invention relates to modulation and demodulation technology in an Orthogonal Frequency Division Multiple Access Passive Optical Network (OFDMA-PON) system, in particular to a system, equipment and modulation and demodulation method suitable for OFDMA-PON. Background technique [0002] OFDMA-PON has become the latest hot technology in the passive optical network (PON) system due to its advantages of high-speed information exchange rate and highly flexible dynamic bandwidth allocation. In the OFDMA-PON downlink transmission, the optical line terminal (OLT) combines the orthogonal frequency division multiplexing (OFDMA) signals of each user through the coupler in the electrical domain, and serves as the driving signal of the optical modulator. After the optical network unit (ONU) undergoes photoelectric detection, each ONU demodulates data or signals from its assigned subcarriers and time slots according to the information obtained through communicati...

AI Technical Summary

Problems solved by technology

The difficulty in realizing the direct detection system of polarization multiplexing lies in that the optical carrier transmitted together with the OFDMA signal is used as the local oscillator signal during photoelectric detection. Therefore, before the polarization beam splitter (PBS), the polarization state of the local oscillator signal Unable to know, that is, the polarization state of the optical carrier cannot be known

After PBS, the separated two optical carriers contain the mixture of the two polarization states of the optical carrier at the sending end, which loses the orthogonality with the two polarization state signals respectively, which brings serious cross-polarization crosstalk, ONU It is difficult for the receiving end to recover the original signal

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