Patent ID: 8886058
Filing Date: 2014-11-11
Classification: H04B

Abstract:
1. A method comprising: receiving an optical signal comprising an optical carrier that has been amplitude and phase modulated according to a modulation scheme and obtaining the optical carrier from the received optical signal using coherent optical reception; converting the optical carrier to an electrical signal; converting the electrical signal to a digital signal in a representation of complex numbers, each complex number being associated with a constellation point of a symbol constellation according to the modulation scheme; performing in parallel first and second carrier phase estimation operations on the digital signal, the first carrier phase estimation operation to track relatively fast phase variations of the optical carrier of the received optical signal to produce a first carrier phase estimation and the second carrier phase estimation operation to track relatively slow phase variations of the optical carrier of the received optical signal to produce a second carrier phase estimation; computing a difference between the first and second carrier phase estimations; and determining occurrence of a cycle slip when the difference is greater than a threshold.