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Coherent optical CDMA

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(joined April 2015)
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Hi, everyone!

I have simulated a coherent OCDMA system (SPECTS-OCDMA), I am using for this project Matlab blocks to encode the signal.
In coherent OCDMA according to each user’s code phase is injected to a signal, 0 or π.
I have simulated the example Optisystem SAC-OCDMA-3users, and modified it in accordance with my requirements.
Comparing SAC-OCDMA with my simulation (SPC-OCDMA), I have got better results.
But I am not sure if I have done the coding process correctly.
Can anyone help me?

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Responses (10):

    • #23209
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      Fernando Teles
      Participant

      Hi, everyone!

      I have simulated a coherent OCDMA system (SPECTS-OCDMA), I am using for this project Matlab blocks to encode the signal.
      In coherent OCDMA according to each user’s code phase is injected to a signal, 0 or π.
      I have simulated the example Optisystem SAC-OCDMA-3users, and modified it in accordance with my requirements.
      Comparing SAC-OCDMA with my simulation (SPC-OCDMA), I have got better results.
      But I am not sure if I have done the coding process correctly.
      Can anyone help me?

      Attachments:
    • #23211
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      Fernando Teles
      Participant

      Matlab codes.

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      • #23222
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        alistu
        Participant

        Hi Fernando, I think it’s okay to see some differences between the results obtained by SAC-OCDMA and SPC-OCDMA, as there are differences between ASK and PSK. But I took a look at your Matlab programs and if it is FBGs that you have simulated using Matlab, then how have you considered parameters such as noise, bandwidth and reflectivity of it?

    • #23225
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      alistu
      Participant

      That’s it I think. Your model is a simplified model for the component and only does what you ideally want the component to do for you. Obviously, better results are obtained this way. I suggest searching in google for MATLAB models of the component and having a look at them. However, I think you could use Optiwave Team advice on this. May I ask why you are using Matlab for this? Thank you.

      +1
    • #23276
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      Fernando Teles
      Participant

      Hi Alistu, thanks for your reply.

      I’ve used Matlab to implement phase shifts the signal, according to the Hadamard code I applied 0 or pi to the frequencies set corresponding to these codes, thus I used the frequencies that the FBG were reflecting on the SAC-OCDMA, I applied shift phase of 0 degrees for these frequencies, and I applied shift phase of pi degree in the other frequencies, what featuring SPECTS system, I am using the modulation OOK, but in the future I will implement PSK or QPSK modulations. I used Matlab for it because I haven’t found components in OptiSystem that satisfy this condition.

      • #23293
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        alistu
        Participant

        You’re welcome Fernando! Thank you for your explanation and the information you provided from your simulated system, which cleared to me what you actually intend to do. But if you haven’t managed to implement the system without Matlab, what are you comparing your system’s results to when you state that you got BETTER results?

    • #23308
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      Fernando Teles
      Participant

      Hi Alistu,
      I compared my simulation with SAC-OCDMA simulation, but I have considered a ideal system therefore I have got better results, but I still not sure if I have done the logic correctly for shift phase using Matlab blocks according what to my system require.

      • #23311
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        alistu
        Participant

        Hi Fernando, I think even if you consider all destructive effects in your simulation, it is possible that you get results that are different from those obtained by using SAC-OCDMA. After all, your system is different from that and this justifies the existence of differences. Unless these two systems have the exact same performance.

        +1
    • #23323
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      Fernando Teles
      Participant

      Ok Alistar, I’ll work in this project for obtain some other results relevant for my system, thank you very much for your replies!

      • #23324
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        alistu
        Participant

        You’re welcome Fernando! And good luck on your research.

    • #49984
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      Akshay Jaiswal
      Participant

      Hii
      can u please help me i want to realise this paper in optisystem. can u share schematic of encoder and decoder of stealth channel.
      https://www.preprints.org/manuscript/201808.0367/v1

    • #66572

      (Awaiting moderation)

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