How can i know the number m of memory registers if i know the number of input bits k,output bits n.Also i know the length of the generator polynomials.
for ex i have n gener polynomials (x1,x2...xi).Is there a relationship between m,k,n and i?

Also is the constraint length equal to k*(m-1) ?

 

What the heck are you talking about?

What is m, k, n, i, x...?

 

Probably this: http://en.wikipedia.org/wiki/Convolutional_code
In a few weeks I will have this in an exam, but as of now I really am not sure that I could help.

 

Convolutional codes can take a while to get your mind around. My recommendation would be to pick some small values for the parameters and walk through some examples by hand. In doing so, look for the underlying relationships. Then change the parameters slightly and see if your observations hold up.