some help please

[feras]

hello everybody ,
i am facing a problem in determined the parameter for my simulation , i am working on qpsk-ofdm and 64qam-ofdm (ROF) and i dont know how to chose the correct parameter for the system component to run the simulation . so is there any help to do that in a right way without any problem please.
and thank you all for helping

[Damian Marek]

Please attach your project file

[feras]

hi Damian Marek,
this is my files , but please dont say to me to use the new ofdm component in optisystem 13

[Damian Marek]

Got it! the 64QAM1 example you attached worked ok for me so I did not touch it. The other one was not working very well so I made some changes.

1) I changed the modulation frequency so that the entire bandwidth of the OFDM signal could be represented by positive frequencies, so around 5 Ghz.

2) I replaced the BER Visualizer with the BER Test Set, so I could use it to ignore some bits if I chose, for example cyclic prefix.

3) I also lowered the gain of the OFDM Demodulation because it seemed a little unrealistic.

4) The filter on the Quadrature demodulator had to be also changed a little.

The back to back transmission worked perfectly.

[feras]

hello Damian Marek ,
thank you very much for your help , but i have tow issue :
1- for the first file ( LTE-64QAM ) that i attached above it is worked as 16QAM not 64QAM , I i want to run it in 64QAM but it didnt give me the right result as the 16QAM did .
2- for the second file ( LTE-QPSK ) i cannt open it , and i am using optisystem version 13 , it give me error massage i will attached it below , also i want to run the simulation on (2.6 GHz) frequency because the LTE system use this frequency .
i hope you nwill help me again please .
i am very thankful to you >

[feras]

hello Damian Marek ,
thank you very much for your help , but i have tow issue :
1- for the first file ( LTE-64QAM ) that i attached above it is worked as 16QAM not 64QAM , I i want to run it in 64QAM but it didnt give me the right result as the 16QAM did .
2- for the second file ( LTE-QPSK ) i cannt open it , and i am using optisystem version 13 , it give me error massage i will attached it below , also i want to run the simulation on (2.6 GHz) frequency because the LTE system use this frequency .
i hope you nwill help me again please .
i am very thankful to you >

[Damian Marek]

Sorry for these slow responses! I do have trouble with OFDM. I am getting some ok results for the 64 QAM but they should be cleaner still working on it, however depending on with version of OptiSystem 13 you have 13.0.# you might not be able to open up the files I submit here.

[feras]

thank you very much really for your help ,
i am using optisystem 13.0 as you see so how can i open the file
and for the 64QAM file i am waiting for your result pleas ,
with my thankful and respect

[Damian Marek]

Please click on the Help->About tab in the OptiSystem window, it will tell you the exact version you have. 13.0.1/13.0.2/13.0.3

[feras]

hello damian , it is 13.0.2

[feras]

error msg

[Damian Marek]

I have made the 64 QAM system work pretty well. Feel free to modify it any further.

[feras]

thnk you very much for ur helping , but the tow file simulation that u attached never worked with me and i don not know what is the problem , i attached u the problem msg in the previous replay

[Damian Marek]

It could be that your slightly older version is not compatible with the project file, because I have no issue opening it. You can try to copy the attached screen shot. The biggest difference is the Decisions component and BER Test Set after the receiver, which removes a lot of the detection errors.

Regards

[Metin Ozturk]

Hello Damian.

Your file 64QAM OFDM is OK, but when I change the parameters of CW Laser to the Visible Light conditions such as Frequency=550 nm and Linewidth=300 GHz, BER becomes unaccaptalbe. I choose those parameters to cover whole visible range like white light.

Thank you.

Best Regards.

[alistu]

Hi Metin,

Could you please upload the OptiSystem implementation file in which you have made the changes you mentioned to the file Damian has uploaded on this page if it is possible? I would like to try solving the problem yet it takes time for me to try and make the changes by myself. Thank you.

Regards

[Metin Ozturk]

I really thank you for your help.

I attached the file. Channel and CW Laser are changed.

Thank you again.

[alistu]

You’re welcome Metin. A look into your design implementation shows the frequency filter used at the receiver is not set according to the center frequency of the signal. I changed it and the result got better. However, I haven’t managed to make it work so as to give desirable results yet.

[Metin Ozturk]

Thank you for your interest.

When I change the CW Laser power to 50 dBm, desirable results obtained. But, I do not know, 50 dBm power for laser is OK or not?

[alistu]

you’re welcome. It is actually a great value as you have mentioned. I suppose if you can get better results using higher input power, then using power booster would be helpful in your design. You can use an optical amplifier after the transmitter with the appropriate gain for this purpose.

Regards

[feras]

thank u very much i will try to do that , but i am sorry what the sgn component mean and what is its work

[alistu]

Hi feras, If you are referring to the decision component, here’s the explanation I found on the help section:

The Decision component processes the I and Q electrical signal channels received from the DSP stage, normalizes the electrical amplitudes of each I and Q channel to the respective m-PSK or m-QAM grid and performs a decision on each received symbol based on normalized threshold settings. It supports the following modulation formats: BPSK, QPSK, 8PSK, 16PSK, 16QAM and 64QAM. The Decision component supports single or dual polarization (SP/DP) multiplexing schemes

Please ask any further questions you might find.

[feras]

thank you very much alisytu for your interested

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