wdm coherent ofdm

[GURINDER SINGH]

I have simulated wdm coherent ofdm for 4 channels. The BER is coming as 0.001952 for one channel and 0.48434 for the other. Is this the correct observation??? Plz help it out..

[Ashu verma]

Hello Gurinder,First of all you can ask any question regarding co-OFDM, at already started ofdm topics in this forum.As there are many discussions at this particular topic.You can also check the optisystem samples for reference.I have given some links below for ofdm

OPTISYSTEM OFDM Example

https://optiwave.com/resources/latest-news/new-version-optisystem-12-2/

BER cannot measured for 16-QAM-OFDM direct detection

16 QAM/ 64 QAM for long distance

If you want to go for more queries click on the link below

co-ofdm

As you mentioned,the bit error rate you are getting is correct or not?
Yes this is correct but this value of BER means error bits are more at the receiving end.For better information you can attach you system so that we can understand it better.Better to use BER error set rather than Ber visulizer.
Regards

[GURINDER SINGH]

i have attached the file…

[GURINDER SINGH]

file attached…..

[GURINDER SINGH]

plz…..anybody help it out….i have attached the file….kindly check it….

[Abhishek Shrama]

Hello Gurinder, The system you have attache d is almost fine,But at the constellation diagram of first channel (As you are using WDM system) is more noisy than at channel 2(you considered only two demux).This is due the reason of the different delay time of two receivers.Also you have used direct SMF of 100KM without any dispersion compensation.You have added a EDFA after 100KM fiber to mitigate the effect of attenuation.I have made several changes in your system
1)Use dispersion compensation
2)Power of transmitters 0dBm and Local oscillator with phase adjustment,always remind as you increase power non-linear effects also increase.
3)Symmetric compensation with DCF
I have used 2 loops each of 50Km SMF and 10KM DCF followed by EDFA’s.You can increase this distance further by increasing power and using non linear compensation like optical phase conjugation.Tell me if you require any assistance regarding some good research papers on this topic.Hope i have made my point clear.Good luck for research

I am attaching a file by doing these modifications

Regards

[GURINDER SINGH]

thanks a lot…..can u tell me which will give better performance out of M-QAM techniques in case of this system??

[Ashu verma]

Hello Gurinder Singh,

I agree with the basic idea given by Abhishek Shrama and just want to answer your query about which QAM will be suitable for your system.
You can try your system with 4QAM 16QAM as you increase Bit/symbol your system efficiency and bit rate both will also increase but noise may increase in case of 16QAM. To compensate the mom linear effects in OFDM system using 16QAM , you can use DSP component introduced by Optiwave in the latest version , this is a interesting MATLAB components which allows to compensate the dispersion induced in fiber and non-linear effects like FWM SPM XPM etc. You can check the forum archives for better help as there is alot of discussion on this topic. Here ↓ i have given links of some of discussions, give me an intimation if you will need more.

100Gbs with DSP

100 Gbps DP-QPSK System with Digital Signal Processing

You can also check optisystem samples for working of DSP component in OSDM system and there are many other examples of OFDM using QPSK , OFDM coherent detection , direct detection etc

[GURINDER SINGH]

I m attaching my file….please suggest how to further reduce the BER uto 10^-9

[Ashu verma]

Hello Gurinder
You are working on OFDM and i would recommend you to use BER TEST SET instead of BER analyzer.It will give the error in bits and BER also.

BER Calculation Using the BER Test Set

Check this link and also search the forum archives on this topic.This discussion has been done many times on forum better to check and understand about use of BER test set.Best of luck for research.

Regards

[GURINDER SINGH]

I have replaced the BER analyzer with BER test set…..I am attaching my file…kindly check it out….and suggest how to reduce BER further..
Regards

[GURINDER SINGH]

file attached

[GURINDER SINGH]

kindly help it out….i have attached the file

[Author]

Posts