RECOVERING DATA FROM QUADRATURE PHASE SHIFT KEYING MODULATED OPTICAL SIGNALS

摘要

Systems, devices and techniques for processing received QPSK modulated optical signals include sampling the received signal at twice the baud rate, thereby producing samples that are then processed as 9-QAM symbols using a decision directed least squares optimization method. Data bits are then recovered from the resulting symbol estimates. The received optical signal may also include dual polarized signals for increased bandwidth capacity.

主权项

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; and recovering data bits transmitted in the optical signal from the estimated constellation symbols.