Cyclic prefix

[Duy Le NguyenParticipant]

Hi everybody. I’m working on the OFDM modulation sample file. But when I change the number of CP points from 0 to another value, BER isn’t zero. I don’t know why.
Could you give me a explanation of why it become bad ?

[Gokul Boro .Participant]

Hi Nguyen,can you please tell if the BER before insertion of CP was zero?

[Duy Le NguyenParticipant]

Hi Gokul. Yes, BER was zero before insertion of CP. And I worked on the OFDM 12OS. You can check the attached file below ( I modified CP points to 128)

Attachments:

1. OFDM-Modulator.osd

[Gokul Boro .Participant]

Hi Nguyen, I am unable to open the file. I would like to know why you are using OS12 component? I have contacted the optiwave helpdesk once, where they replied that OFDM 12 block may sometimes give wrong results. Why don’t you use OS13 block instead.

While changing the parameters, did you increase the fiber length?

Tell me the rest of the parameters you are trying in your system, if you are working with DD-OOFDM system.

Regards

[Duy Le NguyenParticipant]

Hi Gokul.I’m using Optisystem ver 14.0.0.48, maybe it’s the reason you can’t open that file. But you can open OFDM modulation file in your sample folder and try to change the CP point.

I’m using OS12 component because OS13 block give too good constellation result, although have some mistakes in my system.

I didn’t change any parameters except CP points at OFDM modulator and demodulator because I want to know the effect of CP to the system. And I think we will have the better result but it isn’t true?

Regard!

[hosam hussenParticipant]

i have the same problem

[Duy Le NguyenParticipant]

Hi hosam!
This because the start bits and the end bits of BER analyzer. You should set those values to 1024 bits.
Regards.