[Nikolay VolkovParticipant]

Could anybody help me?

[Nikolay VolkovParticipant]

Hello Ajay!

new simulation file is attached.

Attachments:

1. OFDM-64QAM-LTE_v4.osd

[Nikolay VolkovParticipant]

Some of the problems are overcome, but some issues remained unresolved.
1) It is necessary to reduce the value of BER and EVM
2) The value of EVM on the OFDM modulator does not correspond to the constellation diagram, why the diagram looks completely perfect? In optisystem 12 it was entirely different. (see attached image).

Attachments:

1. 

   21.jpg
   

1. OFDM-64QAM-LTE_v4.osd

[Nikolay VolkovParticipant]

Hello! Finally , I am ready with optical part. EVM values is more realistic now, but BER values are still very high. Please, help me, I have some questions for you. I hope you can help me.

1) In optisystem 12 the noise can be seen and constellation diagram isn’t ideal ( see attached image). In the 13 version of Optisystem , the resultant constellation diagram is excellent, why? Where the noise is? EVM is 8-10%, but in the diagram this fact isn’t shown up.
2) Why in the electrical part Electrical Attenuator has no effect on EVM, even at 100 dB of noise, but in optical part
Optical attenuator has utterly faint effect on EVM.
3)How can I calculate SNR? I want to draw a graph SNR/ EVM

[Nikolay VolkovParticipant]

Hello, Damian,

Thank you very much, I continue to work on my project, but all attempts had practically no results. Could you please tell me, channel bandwidth can be configured through the bit rate? I chose 60 mbit/s (10 MHz Channel bandwidth) due to the best constellation diagram result, but is slightly preferable to have Channel bandwidth 20 MHz for LTE signal.

Best regards
Nikolay Volkov

[Nikolay VolkovParticipant]

Ok, thank you. You can do it in OptiSystem 13. I will download a trial version.

Best regards,
Nikolay Volkov.

[Nikolay VolkovParticipant]

Hello, Damian,
Thank you for the help!
I did everything as you said, but I still can’t receive the normal results. I’ve tried different options, but nothing happens. I hope for your help. Very grateful to you in advance!

1) I Connected Ber Set Test, but it shows a huge BER value. I changed many different values of a signal, and the BER value is always or 0,5 or 1.
2) I made everything as you told, but the value of EVM is still bad. Please explain in more detail what it means “You can introduce a gain component so the electrical signal reach the same amplitude as the input signal”. You mean, that the signal output amplitude from QAM modulator has to be the same, as output signal on QAM demodulator?
3) I would like to test the dependence Constellation diagram on the SNR, so after QAM modulator I added Electrical atenuator, but it does not affect the Constellation diagram. In what there can be a problem? I noticed, that with Electrical Power Meter vusualizer, there is in general no noise, perhaps the problem in it?

Best regards,
Nikolay Volkov.

Attachments:

1. OFDM-64QAM-LTE_v2.osd

[Nikolay VolkovParticipant]

Damian, thanks!

The New file of simulation is attached.

Attachments:

1. OFDM-64QAM-LTE-_.osd