Hi Gurpreet, Here are some useful links that I have found, which talk about the basic concepts:
http://www.optics.rochester.edu/workgroups/agrawal/publications/papers/paper_1989_10.pdf
http://core.ac.uk/download/pdf/11533984.pdf
And this one is more practical than theoretical:
http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6813584
I suggest that you at least take a look at the last one. I hope these help.