Method for extracting all-optical bit clock of domain OCDMA (Optical Code Division Multiple Access) system under multi-user environment
A multi-user and environment technology, applied in the direction of time division multiplexing system, transmission system, multiplexing communication, etc., can solve the problems that the clock extraction technology cannot be directly applied to OCDMA and cannot restore user signals, etc. The method is simple, The effect of easy operation
Inactive Publication Date: 2012-11-28
NANCHANG HANGKONG UNIVERSITY
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Problems solved by technology
The clock signal at the time position of the autocorrelation peak is mixed in multiple groups of clock signals formed by interference, and sometimes even covered, so that the user signal cannot be restored
Therefore, the existing clock extraction technology cannot be directly applied to OCDMA
Method used
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[0016] The specific embodiment of the present invention is realized as follows: figure 1 As shown,
[0017] (1) Each user encoded by the encoder 1 enters the optical fiber transmission through the n×1 coupler 2, and then enters the respective decoder 3 through the 1×n coupler, and an optical hardware is added after the decoder 3 of each user A limiter 4, the optical hardware limiter 4 can only pass optical signals equal to and greater than the autocorrelation peak;
[0018] (2) The output signal of decoder 3 after being limited by the optical hardware limiter 4 enters the Fabry-Perot filter 5. The center wavelength of the Fabry-Perot filter 5 is consistent with the wavelength of the light source, which is free The spectral region is the same as the bit rate, so the Fabry-Perot filter 5 will output a clock signal. If the multiple access interference is large, the Fabry-Perot filter 5 will output two or more groups at different positions For periodic clock signals, if the interferen...
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The invention relates to a method for extracting an all-optical bit clock of a domain OCDMA (Optical Code Division Multiple Access) system under multi-user environment, which is characterized by comprising the following steps of: (1) adding an optical hardware amplitude limiter behind a decoder of each user, wherein the amplitude limiters only allow optical signals not less than self relevant peaks to pass through; (2) enabling decoder output signals subjected to amplitude limitation by the optical hardware amplitude limiters to enter a Fabry-Perot filter, wherein the central wavelength of the Fabry-Perot filter is the same as that of an optical source; and (3) because clock signals in self relevant peak positions are obviously stronger than the clock signals in other positions due to therandomness of multiple interference, carrying out amplitude limitation on the output signals of the Fabry-Perot filter once again to extract the correct bit clock signals. The invention has the advantages of simple method and convenient operation and can effectively accomplish the all-optical extraction of the bit clock signals in the self relevant peak positions.
Description
Technical field [0001] The invention relates to an all-optical bit clock extraction method, in particular to a time-domain OCDMA system all-optical bit clock extraction method in a multi-user environment. Background technique [0002] All currently reported OCDMA systems assume that the signal is judged at the time position of the autocorrelation peak. As for the autocorrelation peak clock extraction technology, it has never been reported. [0003] All-optical bit clock extraction technology has been deeply studied in other communication methods (such as OTDM), and a variety of all-optical clock extraction schemes have been proposed, such as Fabry-Perot filter (FPF), stimulated Brillouin Scattering (SBS), mode-locked lasers and phase-locked loops, etc. However, in a multi-user environment, multiple access interference and auto-correlation sidelobes (cross-correlation and auto-correlation) exist in the OCDMA system, and the distribution of these interferences is also regular, and t...
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IPC IPC(8): H04J3/06H04B10/12H04B1/711
Inventor 万生鹏
Owner NANCHANG HANGKONG UNIVERSITY