Q FACTOR

Hi Lavanya,

Generally, Q- factor is dependent on the factors that make the system performance better. This includes reducing dispersion which might lead to ISI, nonlinear effects that may appear in a WDM system as four-wave mixing and/or cross-phase modulation, and noise of any kind.

Regards

increase power
depends upon data rate
bw of multiplex
https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0ahUKEwjtyYrn6M7MAhXHJI4KHatwCPoQFggoMAE&url=http%3A%2F%2Fwww.issr-journals.org%2Flinks%2Fpapers.php%3Fjournal%3Dijisr%26application%3Dpdf%26article%3DIJISR-14-301-03&usg=AFQjCNFq5reRBxXmcjAWxXxd0eJ4Zia2QA&sig2=XBDUgpEACyKBkTx_dUN3jA
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https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&cad=rja&uact=8&ved=0ahUKEwjtyYrn6M7MAhXHJI4KHatwCPoQFgg4MAM&url=http%3A%2F%2Fwww.ciscopress.com%2Farticles%2Farticle.asp%3Fp%3D30886%26seqNum%3D5&usg=AFQjCNEfhAYMaiGnO2FQVPbDgWy3dStH8g&sig2=gxA3_fm2tO1EO96JOuHkhQ
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https://books.google.co.in/books?id=8IcNZu1smOwC&pg=PA54&lpg=PA54&dq=wdm++with+high+quality+factor&source=bl&ots=5ugGXyKW60&sig=dreBv4HC8UoPeOheDIoDooKDPCE&hl=en&sa=X&ved=0ahUKEwjtyYrn6M7MAhXHJI4KHatwCPoQ6AEIVjAI

Hello.
I would like to mention that there are various ways to increase the quality factor for various system designs. First you need to specify for what application you are designing your system.
As mentioned by Mr Umer you can increase power to increase the quality factor but it has has an adverse effect on the channel as non linearities come into play but you can increase the transmission power.
I would provide you some links which you could refer to. I hope these will help.

Thanks
http://www.ijltet.org/wp-content/uploads/2013/08/4.pdf

16 Channel WDM System Design

I would also like to mention that you can also use various modulation techniques to improve your quality factor as the practical aspects of the generation of some of the most frequently used modulation formats is known.
Also The location of the maximum of the Q factor with respect to the averaged launched power shows that nonlinearity (as i mentioned earlier) tolerance of the different formats studied is quite different. NRZ has the lowest nonlinearity tolerance. The pulse-width is not constant for NRZ which leads to different interplay between dispersion and self-phase modulation. The other reason is related to the inter-channel cross-phase modulation and four-wave-mixing. As it has been already mentioned the faster and further the pulse spreading occurs the smaller the impact of the intra-channel nonlinearities would be. This is the basic idea behind the “pulse-overlapped” transmission. Obviously, the shorter RZ pulses will spread faster which will combat the intra-channel nonlinearities better.

Hope this will help
Thanks

Hello Iavanya,
I agree with Umer Nuzhat and Hamza. You can take up all the suggestions put forth by all the members and check for the results. You would definitely see a change in your quality factor.
I would suggest you to use different modulations schemes too. That can help too.
Regards

Hello Lavanya,

I would suggest to increase the launching power if it is not be an issue, you may also increase the symbol rate i.e symbols per sample that will reduce probability of error and will make your results better.
One more thing you can do is slightly increase the sequence length.
I hope this will be helpful.

Regards

Burhan