3results about "Frequency-division multiplexing selection" patented technology

The invention discloses a quantum key distribution parameter optimization method in a space-frequency multiplexing common-fiber transmission system. The method is suitable for a quantum key distribution light-emitting network of space-frequency multiplexing common-fiber transmission. The invention provides a quantum key distribution parameter optimization method based on a coordinate descent method, which mainly considers the problem that the quantum key distribution performance of fixed parameter setting is reduced due to channel parameter changes such as background noise and channel attenuation of a quantum channel in a space-frequency multiplexing common-fiber transmission system. The method aims at optimizing quantum key distribution parameters in real time according to channel parameters and improving quantum channel performance. Technical support is provided for fusion transmission of quantum key distribution and a classic optical network, and the application process of quantum key distribution is promoted.

This invention discloses an uplink and downlink wavelength locking method and system for Time Division Frequency Division Multiplexing Passive Optical Network (TFDM-PON), including a downlink wavelength difference estimation and compensation stage; an uplink carrier construction and transmission stage; and an optical line terminal (OLT) side reception and demodulation stage. In the downlink wavelength difference estimation and compensation stage, the frequency offset between the OLT transmitting source and the ONU local laser is estimated through the reception and processing of the downlink coherent optical signal by the optical network unit (ONU), and the local laser frequency is compensated. In the uplink carrier construction and transmission stage, an uplink coherent optical signal with controllable spectrum is generated based on the local laser source locked in the downlink wavelength difference estimation and compensation stage. In the OLT side reception and demodulation stage, the OLT receives the uplink coherent optical signals from each ONU, utilizing the predictability of the uplink optical carrier frequency. This invention provides an uplink and downlink wavelength locking method and system for TFDM-PON, effectively reducing the complexity of digital signal processing on the OLT side and improving the stability, reliability, and scalability of the system in scenarios with multiple ONUs concurrent access.

The invention relates to the technical field of radio over fiber communication, and provides a hybrid transmission optical forward transmission system and a related method. The method comprises: separating an input bit stream into index bits and communication modulation bits; generating an unmodulated AFDM waveform with a corresponding chirp slope according to the index bit control, and processing the unmodulated AFDM waveform into a first baseband signal; modulating the communication modulation bit to an AFDM subcarrier to generate a second baseband signal, and carrying out up-conversion on the second baseband signal to obtain a first radio frequency signal; performing frequency division coupling on the first baseband signal and the first radio frequency signal to generate a mixed radio frequency driving signal; receiving the optical carrier frequency division mixed signal and converting the optical carrier frequency division mixed signal into a mixed radio frequency signal of an electric domain; separating the mixed radio frequency signal into a digital baseband signal and an analog radio frequency signal; performing discrete affine Fourier transform on the digital baseband signal, and determining chirp slope of the digital baseband signal through peak detection so as to demodulate index bits; and controlling the switching network to gate the analog radio frequency signal to the corresponding transmitting antenna according to the index bit.