OFDM with BICR

[Gokul Boro .]

Hi everybody,
Can anybody help me to know whether the system attached here in is right or not? Also if the design is ok then please help me in setting the parameters, including the pilot/training symbol insertion.

Attachments:

1. BICR-OOFDM-System-tx.osd

[alistu]

Hi Gokul,

I don’t know about the WDm interleaver you have used, but your whole system seems to have been set right. However, I generally suggest always using Optisystem sample and making the necessary changes to that.

Can you please say how many subcarriers, pilot signals, etc you want to use? And I will set them for you to see as an example. In the meanwhile, please have a look at the OptiSystem OFDM sample to get an overall idea of the setting.

Regards

[Gokul Boro .]

Thank you very much Alistu.. You have been a great help to me.
These are the parameters:
FFT length- 256
Information carried sub-carriers- 128
CP length- 1/8 of symbol period
I am not sure about the number of pilot signals. I was planning to go into it by changing arbitrarily.

[alistu]

You’re welcome! I have set the values according to the parameters you have mentioned. Please compare the OFDM components properties (for both modulator and demodulator). I am not sure if the number of training symbols should be set as the number of CP points. In OptiSystem OFDM sample, in demodulator both have the same value, while in the modulator, the values are different (I have done the same thing here).

Attachments:

1. BICR-OOFDM-System-tx-modified.osd

[Gokul Boro .]

Hi alistu,
Actually in this design I used the Inter-leaver to separate the transmitted SSB-OOFDM signal as Optical carrier and OOFDM signal. But I am not sure whether the interleaver I am using is performing the same or not.
I have tried this design with 16QAM but the constellation at the output is not 16QAM. Should I redesign a block for constellation viewing or there is some flaw in the whole design itself?
Thank you

[alistu]

Like I suggested, you’d better start with the OFDM sample file and make the changes you want to it step by step and see if you can get the results for each step. For example, first use 16-QAM modulation and try to get the results and so on. Finally, you can add the interleaver. I cannot say with certainty if your overall design is correct.

[Gokul Boro .]

Thank you Alistu,
But I don’t have any osd file for 16QAM system. Can you please share if you have it?

[alistu]

You’re welcome. There is one Optisystem sample file in the OptiSystem sample folder for 16-QAM OFDM systems with direct detection for signle polarization (as in your case). It is named “OFDM Coherent Detection Single Port Single Polarization 16QAM” and you can find it in the folder “OFDM Systems” in “Advanced Modulation Systems”.

[Gokul Boro .]

Thank you Alistu,
Yes I have already tried it, and still working with it to get the desired results…

[alistu]

You’re welcome. You’d better start with that file and if you feel you need help, please upload the sample with your changes applied on it here.

[Author]

Posts