Patent ID: 8913901

Claim:
An optical receiver system comprising: a digital signal processor (DSP) comprising an equalizer configured to equalize a signal representative of a quadrature amplitude modulated (QAM) optical signal transmitted over an optical transmission path, said equalizer being configured to equalize said signal by application of an equalization algorithm to said signal, said equalization algorithm being characterized by a cost function, said cost function being a function of a Euclidian distance between detected symbols of said QAM optical signal at an output of said equalizer, wherein said cost function is: J=E [( D 2 −|R 2 −|Re ( u ( n ))| 2 |) 2 ]+ E [( D 2 −|R 2 |Im ( u ( n ))| 2 |) 2 ] where J represents the cost function value E[.] denotes expectation, D is said Euclidian distance and is a minimum Euclidian distance between said symbols, R 2 is equal to ½ of the average symbol power at said output of said equalizer, Re(u(n)) is a real portion of said output of said equalizer for a current update cycle, and Im(u(n)) is an imaginary portion of said output of said equalizer for said current update cycle.