method to combat IQ imbalance

Hi,
I am a student of IIT Madras (chennai),India and working for the
compensation of IQ Imbalance in OFDM system.

I followed ieee  paper "compensation of IQ imbalance in OFDM system" by
Jan Tubbax et al and found it very interesting and implementable.
I wrote Matlab code for this method but alpha and beta (parameter as
defined in the paper--functions of gain and phase imbalance))
estimation results were not satisfactory and they were varing a lot and
also some time were not close to actual value also.Ofcourse if I use
actual value of alpha and beta instead rest of the things go smoothly.

But alpha and beta estimation is still trouble for me and I am really
grappling with it.
Should I go for any other method ?
Please tell me if any of you could help me in this regard.You can send
me your code  or  I can send mine so you point out my mistake.
I would be very grateful to you for any kind of help.

Thanks in advance,

Gaurav