Forum Replies Created

    #67370
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    alistu
    Participant

    Dear Ahmad,

    Thank you very much for your response. I believe the number of FFT points are represented as “maximum number of subcarriers” in the BER Test Set.

    I do have basic familiarity with OFDM theory, but the BER Test Set calculation method is still not clear to me. To be more specific, if I want to implement an OFDM-CDMA structure, where every bit of the binary input is first multiplied by a code word, it is easy to implement the multiplication block through Matlab Component after the BER Test Set – please refer to an OFDM sample. That way, since the sequence length in the layout parameters is fixed, the overall bit rate and the input word length are reduced. However, I cannot figure out how to define the BER Test Set bit sequence the same as the Matlab Component output, so it correctly calculates the error.

    Another approach is to replace the BER Test Set with a suitable program via Matlab Component, but it would then require a solid knowledge of how the BER Test Set works in OptiSystem. And that is why I started the thread.

    Thank you again for helping me out.

    Best regards,
    Alistu

    #54214
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    alistu
    Participant

    Hi Ahmad,

    Thank you for your response. Regarding BER for OFDM, the help section only emphasizes in a few lines the importance of assigning the same values to the component as the ones used in OFDM transceivers with no other explanations on how the parameters are considered in calculations.

    +1
    #54028
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    alistu
    Participant

    Great! Thank you very much Ahmad.

    #51191
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    alistu
    Participant

    .

    #51183
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    alistu
    Participant

    The file:

    #51181
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    alistu
    Participant

    Hi,

    Here I have attached an .osd file of an implementation of a bidirectional system which makes use of coherent QAM both in downstream and upstream. When the downstream signal passes through the channel, it is splitted to two branches, with one going to the downstream receiver and the other to upstream transmitter, to be used as an optical source instead of the laser (which is the whole point of using remodulation technique, BTW). The problem is, though, that there is no upstream signal after the bidirectional fiber, as it can be seen by ‘Optical Spectrum Analyzer_2’. What is the problem?

    The system error is not important for me here. I just want to have the signal. Thank you in advance!

    #50508
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    alistu
    Participant

    In the most common cases, remodulation makes use of RSOA or power splitters. It is not important to me whether or not the system works well in terms of error – that can be fixed. I’d rather to get it to work first, to send the upstream signal through a birdirectional channel and get a signal at upstream receiver.

    #38687
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    alistu
    Participant

    Yes, here’s the screen shot from all users.

    BTW, did you try to change the FBG frequencies to make it work?

    #38678
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    alistu
    Participant

    Here they are.

    Regards

    Attachments:
    #38673
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    alistu
    Participant

    Here are screen shots from each of the 3 users BER analyzer. The third user signal is probably corrupted, so the BEr analyzer does not show anything. I will let you know in case any progress will be made in making it work.

    #38666
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    alistu
    Participant

    Hi Irfan,

    This file is OptiSystem SAC-OCDM sample as far as I am concerned (so you can find it in OptiSystem samples). I ran the simulation and it went smoothly with acceptable results except for the third user (which you should first enable in the simulation BTW). If you cannot open the file or do the calculation, this is a technical issue and you should contact Optiwave, which will probably answer after the weekend.

    I suspect something might be wrong with the way the third code is generated by FBGs. I haven’t worked much on SAC-OCDMA, but if you are interested to know how the codes should be generated, I suggest you thoroughly go through the related comprehensive discussion in the link below:

    how to implement sac ocdma?

    Regards

    #35599
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    alistu
    Participant

    It’s very kind of you Umer! And congratulations to you on earning your second gift certificate!

    #35556
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    alistu
    Participant

    Thank you very much Antika! I would like to congratulate you on earning your first gift certificate and wish you luck with your research work and forum participation.

    Regards

    #35555
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    alistu
    Participant

    Thank you Sahil! And congratulations to you for earning the third gift certificate. Keep up the good work!

    #35554
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    alistu
    Participant

    Thank you Aabid. And congratulations to you and other members who have recently attained gift cards.