inter symbol interference

[lavanya krishnanParticipant]

how can I reduce isi in a wdm system?

[Dr. Dhiman KakatiParticipant]

Hi lavanya, I am giving you some theoretical concept why the ISI occurs in WDM system, You may find this helpful.

one of the reason for ISI in wavelength division multiplexing is due to the less channel spacing, i.e. less difference in wavelengths or frequencies and at a high data rate transmission. On way to reduce the intersymbol interference (ISI) is to use return-to-zero (RZ) format in place of Non Return to Zero (NRZ) format. The RZ format in optical communications has advantages over the more frequently used non-return-to zero format, mainly because the RZ-modulated signal can withstand better the impact of fiber nonlinearity and polarization-mode dispersion. the most widely used method is the polarization interleaving method. However, for the very small channel spacing, the power leakage from one channel to its adjacent channels still remains. To reduce this leakage, one need to use filters with sharp spectral response, typically consisting of more than one stage- such filters are expensive, exhibit high insertion loss, and often cause large intersymbol interference (ISI). the adjacent channel interference (ACI) can be reduced by the dispersion interleaving method. these are the two methods- POLARIZATION INTERLEAVED & DISPERSION INTERLEAVED WDM SYSTEMS. you may find so many papers on these two topics on the internet.Once you make the design you have to see which method will be fruitful for you.

Regards

[lavanya krishnanParticipant]

thanks. but I need to know is there any device(block) which can reduce the isi in optisystem?

[Dr. Dhiman KakatiParticipant]

you can try using DSP at the receiver side for reducing or cancelling the ISI.

Regards

[lavanya krishnanParticipant]

where can I find DSp

[Dr. Dhiman KakatiParticipant]

You can find the DSP block following the component library default/receivers library/digital signal processing/ and choose accordingly depending on your design.

Regards

[gaganpreet KaurParticipant]

to find any component u right click on the folder of default components and you can search for any component in that

[Dr. Dhiman KakatiParticipant]

Dear Lavanya, Basically you have to compensate for dispersion. There are various techniques as I have already mentioned.

Regards

[lavanya krishnanParticipant]

thanks dhiman for ur help

[lavanya krishnanParticipant]

dear dhiwan can get a sample how to use DSP block

[Shahbaz QureshiParticipant]

Hi Lavanya,

Dhiwan explained it well along with the techniques that can be used. However, I am attaching a link about application of DSP in 100 Gbps DP-QPSK System. Hope this will help you.

LINK:

100 Gbps DP-QPSK System with Digital Signal Processing