very interesting article from Bonada and Serra of MTG-UPF. (i guess you need ieee xplore to access the pdf.) http://ieeexplore.ieee.org/iel5/79/4116828/04117930.pdf?isnumber=4116828&prod=JNL&arnumber=4117930&arSt=67&ared=79&arAuthor=Bonada%2C+J.%3B+Xavier+Serra