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FTTH using OCDMA

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(joined December 2014)
Participant

Hello,
How is the encoding done in the examples FE-OCDMA-3Users and FE-OCDMA-7Users and how to increase the no. of users?
Thank you,

Responses (41):

    • #16821
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      sulaiman
      Participant

      Hello,
      How is the encoding done in the examples FE-OCDMA-3Users and FE-OCDMA-7Users and how to increase the no. of users?
      Thank you,

    • #16865
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      Damian Marek
      Participant

      If you have more users you only really need to have larger code words. Then in the physical SAC-OCDMA type system you would need more fiber bragg gratings.

      +3
      • #16901
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        Heitor Galvao
        Participant

        Good afternoon there are some sample file?

    • #16868
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      sulaiman
      Participant

      thanks Mr Damian but how is it done I need to know how is the system work

    • #16952
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      Fady
      Participant

      Could you please post a sample for larger no. of users (more than 7 users)? Thank you and happy new year!

      • #16979
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        Damian Marek
        Participant

        Hi all,

        There is a sample project on this subject in the Access systems folder that I have also attached. The code word has a length of 8 and the coding is done using Hadamard code.

        Regards

        • #16992
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          Heitor Galvao
          Participant

          Thank you

        • #17003
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          Heitor Galvao
          Participant

          Hi Damian this file in which version of optisystem?

        • #17027
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          Damian Marek
          Participant

          The version number is OptiSystem 13.0.1

        • #17102
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          Heitor Galvao
          Participant

          Ok

        • #41794
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          rafik hisham
          Participant

          Hey it’s a great work but i have some questions would you help me with it ? if i want to extend number of users in this system what should i do which codes i use? which range of wavelength and what about the Receiver decoder ?? thanks in advance

    • #16996
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      Ravil
      Participant

      very useful, thanks Damian!

    • #17013
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      sulaiman
      Participant

      Hi Damian,could you pleas give example 9uses
      and how i can put the code in the FBG

      • #17029
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        Damian Marek
        Participant

        Hello,

        Could you attach an article or paper with 9 users? From my quick look I didn’t find any with 9 users, so I am not exactly sure how to generate the code words.

        Regards

    • #17034
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      sulaiman
      Participant

      Hi Damian,
      How I can put the code words in FBG for FE-OCDMA-7-Users

      • #17048
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        Damian Marek
        Participant

        Hi Sulaiman,

        Once you have the code words, that are generated first by the type of code you are using and the number of users, you can code each users spectral content by assigning each bit of the code word a wavelength. In our OptiSystem example, the range of wavelengths goes from [1549 1549.5 1550 1550.5 1551 1551.5 1552 1552.5] nm. You will notice 8 wavelengths for a code word of length 8.

        Now assigning the rule that a bit value of 1 means the user’s signal will contain that wavelength spectral content, we can place four fiber bragg gratings to create stop pass filters for the undesired spectrum (bit values equal to 0). From Hadamard coding, there will always be 4 zeros in every code word.

        I have attached a picture of the 7 users and their code words following Hadamard coding.

        Regards

    • #17119
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      sulaiman
      Participant

      Hi Damian ,
      Thanks a lot for answer but I need to know how I put the codeword0nFBG in the layout simulation and how i can used anther type of coding like Modified Quadratic Congruence (MQC) codes.

      +2
      • #17175
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        Damian Marek
        Participant

        Hi,

        Maybe I am misinterpreting what you mean by put the codeword on FBG, but I think my earlier reply answered that. If you take a look at the example file that comes with OptiSystem “FE-OCDMA 7 Users.osd” you will see that the first user has codeword: 10101010 which means we need to remove the spectral content belonging to wavelength2, wavelength4, wavelength6 and wavelength8. Using a FBG centered at the undesired wavelength you can reflect only that wavelength, so after placing 4 in succession the four wavelengths can be removed.

        I have attached some screenshots of the project to hopefully make it clearer.

        I am not familiar with MQC, but I believe once you can find the codewords for the different users then the procedure of placing the FBG’s is the same. Let me know if anything is unexplained!

        Regards

    • #17173
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      Fady
      Participant

      Could you please answer Sulimans question above? Many thanks

    • #17187
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      sulaiman
      Participant

      Thanks Damian
      I try to make user 3 on in the examples FE-OCDMA-3Users but it remain off and the BER decrease could you pleas solve this problem

      • #17206
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        Damian Marek
        Participant

        In the White Light source you need to both Enable the component ins the Simulation tab and loss convert Noise Bins in the Noise tab.

    • #17216
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      sulaiman
      Participant

      Thanks Damian
      Could you please give attachment

      • #17250
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        Damian Marek
        Participant

        Of course! Note this is a file from OptiSystem 13, so you will need the most recent version to run it.

    • #17278
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      sulaiman
      Participant

      Thanks Damian
      could you pleas give attachment to make user 3 on and give good BER for 3 user in FE-OCDMA-3-Users.

    • #17383
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      sulaiman
      Participant

      HI Damian
      could you pleas give attachment to make FE-OCDMA-3-Users for FE-5users

      • #17389
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        Damian Marek
        Participant

        Hi Sulaiman,

        The exact coding choice you want to use will change the gratings used, for example the Hadamard or Walsh code which is what I am most familiar with has codewords of length 2^k, so 4, 8 etc. The number of users that it is optimized for is one less than the codeword length, so 3 and 7. I don’t believe a 5 User FE-OCDMA Hadamard is a common system, but you could make it by simply removing two users from our 7 User example we have.

        If you have a different code word scheme just let me know the code words and I can make it quite simply.

        Regards

    • #17552
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      Fady
      Participant

      By the way what is the codes used for the 3 users example? Thanks

    • #17553
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      sulaiman
      Participant

      HI Damian
      what is type of code used in FE-OCDMA-3-UsersON

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