Patent ID: 9698914
Date: 2017-07-04
CPC Classifications: H04B,H04L

Claim:
1. A method of recovering data in an optical communication system, the method comprising: receiving an optical signal that is modulated using a quadrature phase shift keying (QPSK) modulation scheme; sampling the received optical signal to generate a group of samples comprising samples at time instances that are odd integer multiples of T/2, where T represents a symbol time interval of the QPSK modulation scheme; estimating received constellation symbols from the group of samples using a decision-directed least radius distance (DD-LRD) algorithm for blind equalization, wherein the DD-LRD algorithm includes iteratively refining symbol estimates using an adaptive filter; processing an output of the blind equalization using a decision-directed least-mean-square (DD-LMS) channel equalizer; and recovering data bits transmitted in the optical signal from the estimated constellation symbols.