Patent ID: 8977136
Filing Date: 2015-03-10
Classification: H04B,H04L

Abstract:
1. A receiver comprising a carrier recovery module, wherein the carrier recovery module comprises: a port arranged to receive a receiver input signal that is representative of an optically coherent signal that was received by the receiver as a result of a transmission, by an optical transmitter, of a transmitter signal that is a carrier signal that is being modulated by information; a reference signal generator that is arranged to generate a reference signal that estimates the carrier signal; a decision module that is arranged to demodulate the receiver input signal by the reference signal to provide a demodulated signal and to evaluate the demodulated signal to provide a decision module output signal that estimates the carrier signal; wherein the reference signal generator comprises: a delay and rotation module that is arranged to delay receiver input signals to provide delayed receiver input signals and to align the delayed receiver input signals by a rotation that is responsive to the decision module output signal thereby providing aligned signals; and a multiplication and summation module that is arranged to generate the reference signal by calculating a weighted sum of the aligned signals; wherein the multiplication and summation module comprises multiple adders and only a single multiplier; wherein the multiple adders are arranged to add the aligned signals to provide an first sum and wherein the single multiplier is arranged to multiply the first sum by a single coefficient to provide the weighted sum of the aligned signals.