Coherent CDMA Receiver for Multipoint Optical Transmission
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current DSP architectures in coherent CDMA systems are limited to point-to-point transmission and are not applicable to multipoint-to-point systems, and the existing CDMA architecture in wireless communication is not fully compatible with optical communication systems, where polarization mode dispersion and differential group delay effects further complicate signal recovery.
Innovation Solution
A receiver with two input ends for X-polarization and Y-polarization digital signals, a despreading module, and a multiple-input multiple-output equalization module that synchronizes and despreads signals using N delay values and spreading codes to recover data from multiple transmitters, effectively compensating for differential group delay effects in optical fiber channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If current DSP architecture is used for coherent receiver, then point to point transmission is supported, but multipoint to point transmission is not applicable
Solution Approach 1:
The patent implements a universal DSP architecture that can handle both point-to-point and multipoint-to-point transmission modes through configurable despreading modules. The receiver uses N despreading modules that can be activated based on the transmission mode, allowing the same hardware to serve multiple functions without requiring separate dedicated architectures for each transmission type.
2Adaptability or versatility
If wireless communication CDMA architecture is applied to optical communication system, then multipoint access is enabled, but polarization mode dispersion and differential group delay effects cannot be compensated
Solution Approach 1:
The patent introduces intermediate processing modules between the despreading stage and the decision stage to compensate for polarization mode dispersion and differential group delay effects. Specifically, polarization demultiplexing modules and equalization modules are inserted as intermediaries to correct signal degradation caused by fiber transmission, thereby maintaining signal quality while enabling CDMA multipoint access in optical systems.
3Productivity
If dual-polarization signals are transmitted through fiber, then transmission capacity is increased, but polarization mode dispersion and differential group delay effects are introduced
Solution Approach 1:
The patent converts the harmful effects of polarization mode dispersion and differential group delay into beneficial information by using these effects as synchronization references. The system deliberately exploits the differential group delay to achieve precise timing synchronization between multiple transmitters, and uses polarization mode dispersion characteristics for polarization state detection and compensation, thereby transforming transmission impairments into useful synchronization aids.
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
Embodiments of the present invention provide a receiver and a data receiving method. The receiver in the present invention includes: two first input ends, configured to receive a digital signal of an X-polarization state and a digital signal of a Y-polarization state; a despreading module, configured to despread the digital signal of the X-polarization state and the digital signal of the Y-polarization state based on N delay values and spreading codes of N transmitters, to obtain N first baseband signals and N second baseband signals, where the N delay values are respectively determined based on differences between synchronization positions of first polarization states and synchronization positions of second polarization states of the N transmitters; and a multiple-input multiple-output equalization module, configured to perform equalization filtering processing on the N first baseband signals and the N second baseband signals, to obtain recovered data of the first polarization states and recovered data of the second polarization states of the N transmitters. In the embodiments of the present invention, the coherent CDMA multipoint to point data transmission in an optical communications system is implemented.