A dual-polarization, 2-subcarriers code orthogonal, orthogonal frequency division multiplexed signal carrying information bits is transmitted in an optical communication network without transmitting a corresponding pilot tone or training sequence. A receiver receives the transmitted signal and recovers information bits using a blind equalization technique and by equalizing the 2-subcarriers OFDM signal as a 49-QAM signal in time domain with a CMMA (constant multi modulus algorithm) equalization method.

A group of data symbols for a current block of data symbols in multiple blocks received over a communication channel is equalized, based on a pilot block, to generate a group of equalized symbols. The group of equalized symbols is de-rotated as a function of a current phase estimate to determine initial de-rotated equalized symbols. The phase estimate is an estimate of phase caused by noise for blocks previous to the current block. Additionally, a phase metric is calculated from real and imaginary parts of the initial de-rotated equalized symbols, wherein the phase metric estimates phase caused by noise for the current block. The current phase estimate is updated with the phase metric. The initial de-rotated equalized symbols are de-rotated by the phase metric to determine final equalized and de-rotated symbol estimates. The final equalized and de-rotated symbol estimates are output. Apparatus, methods, and computer program products are disclosed.

A method and apparatus for performing residual phase noise compensation is described. A coarse carrier compensation of a received modulated signal is performed to obtain a coarse carrier compensated signal and a trellis-based residual carrier recovery is performed to estimate a residual phase noise of the coarse carrier compensated signal. The coarse carrier compensated signal is compensated based on the estimated residual phase noise.

In accordance with a first aspect of the present disclosure, a communication device is provided, comprising: a receiver configured to receive one or more signals from an external communication device; a classifier configured to classify the external communication device using the signals received by the receiver and to output a corresponding classification result; and a processing unit configured to change one or more configuration settings of the communication device in dependence on the classification result. In accordance with a second aspect of the present disclosure, a corresponding method of operating a communication device is conceived. In accordance with a third aspect of the present disclosure, a corresponding computer program is provided.