DDO-OFDM-DWDM-64QAM

[ali]

I got a paper simulation. But when the program runs is stuck, please help.
The article also send

[Ashu verma]

Hello Alireza
Can you please attach your system file for more understanding?You can also share the screen shot of the system
What type of problem you are facing,is there a massage of not responding?or ay simulation warning?
For just information,have you already made a 35 channel WDM system using OFDM for 1.05 Tb/s?

[alistu]

Hi Alireza,

I have also worked on optical OFDM systems and have simulated some of Dr Matin’s students’ works regarding this subject to reproduce the results. I haven’t seen your simulation yet and if you attach it here, we can help you better. But I can tell you that if you use Optisystem’s DDO-OFDM sample file (in Optisystem samples folder) to make this system, you’ll have no problem reproducing it. Just use a demux, copy the optisystem DDO-OFDM sample to make them as many as the number of users, and then set each user’s lasers’ frequencies to those mentioned in the paper and that’s it!

Cheers!

[ali]

Thanks to all friends
I ATTACH my simulation file

[alistu]

Found the problem! I have been working on the same subject and I also encountered the same problem when I was simulating one of Alatawi’s works. I contacted him 2 months ago and he told me that in his simulations, he had not considered the nonlinear effects of the fiber at all. You must do the same thing to get the same result as he did.

Cheers!

[alistu]

Another thing I have noticed in your simulation is that you haven’t used the proper values for the optical amplifiers. you must consider the overall attenuation (or loss) of each line and then determine the optical amplifiers values. By the way, if you want to consider the nonlinear effects, lower your laser powers, say, to -5dBm to avoid signal corruption.

[ali]

Thanks to guide you
Can you do that you say to non-linear changes and also the appropriate values for optical amplifier, for example, for four-channel WDM and two loop implementation and get the desired result? Because I can not get the desired result for BER and constellation
If you did, please attach result

[alistu]

In order to disable nonlinearities, you need to disable the nonlinearities in your optical fibers’ properties sections where there is a tag “nonlinearities”. And for the optical amplifiers to have the same amount of amplification as the amount of attenuation caused by the optical fibers, you are going to have to multiply each optical fiber’s length by its attenuation (or loss) and then put the value of the corresponding optical amplifier equal to that.

[alistu]

Oh, and I have to add, nonlinearities exist in optical fibers and if you disable the optical fiber line nonlinearities, then the results you get are not reliable. So is the case with the paper you are trying to reproduce whose results. So I suggest that instead, you lower the power of all the lasers to, say, 0 dBm, lower the bit rate and shorten the length of the fiber and get more realistic results instead.

[alistu]

Dear Hadi, The work done in the paper you have attached has been done as part of a master’s thesis. I recommend that you have a look at the thesis “High Data Rate Coherent Optical OFDM System for Long-Haul Transmission” done in university of Denver. At the end of the thesis, all related paper, including the one attached here, are there.

[ali]

thank you alistu
Is simulation file in this case that would help me do you know?

[alistu]

You’re welcome. Hadi. I do not have the simulated files of the project but as far as I am concerned, the EXACT previous OptiSystem versions CO-OFDM sample has been used to do the simulations of the project. I suggest that you also start with the same file. Then use MUX and DEMUX to make a WDM system.

[alistu]

I am sorry I realized you are using direct detection and not coherent detection, as in the thesis I suggested. But it does not matter as long as you use the DDO-OFDM sample file from optisystem. Just use the OFDM components with optisystem 12 OFDM components to acquire the same results as the paper you are trying to simulate.

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