Digital filter arrangement for compensating group velocity dispersion in an optical transmission system

An optical transmission system (OTS), comprising:

• one or more optical fibers;
• a transmitter;
• and
• a receiver;
• wherein the transmitter is configured to transmit, on the basis of a first digital signal, a modulated light signal via the one or more optical fibers to the receiver;
• wherein the receiver is configured to receive the modulated light signal via the one or more optical fibers from the transmitter and convert the received modulated light signal into a second digital signal;
• wherein:
• the transmitter is configured to pre-compensate group velocity dispersion (GVD) of the modulated light signal on the basis of the first digital signal using a digital filter arrangement (DFA), or
• the receiver is configured to compensate GVD of the received modulated light signal on the basis of the second digital signal using a DFA;
• and
• wherein the DFA comprises:
• a DFA receiver;
• M discrete Fourier transform (DFT) filters, wherein M is a positive integer, wherein each DFT filter of the M DFT filters is implemented by a fast Fourier transform (FFT) algorithm of a size T smaller than a size N and by an interpolation algorithm;
• and
• a compensation filter, implemented by a delay network and a linear combination algorithm;
• wherein the DFA receiver is configured to:
• receive a sequence of samples of a digital input signal in the time domain in the form of consecutive blocks of size L, wherein each block of the consecutive blocks comprises L consecutive samples of the digital input signal;
• wherein the M DFT filters are configured to:
• generate M discrete Fourier transforms of a current overlap block and of M−1 delayed versions of the current overlap block, wherein the current overlap block is of the size N and the size N is greater than the size L, wherein each generated discrete Fourier transform is of the size N and comprises N entries, the current overlap block comprises samples of a current block of the blocks and the N−L last consecutive samples of a directly previous block that was received by the DFA directly before the current block of the blocks, and
• wherein the compensation filter is configured to:
• filter the N entries of the generated M discrete Fourier transforms to generate an output discrete Fourier transform with N entries.

A method, comprising:

• receiving a sequence of samples of a digital input signal in the time domain in the form of consecutive blocks of size L, wherein each block comprises L consecutive samples of the digital input signal;
• generating M discrete Fourier transforms wherein M is a positive integer, of a current overlap block and of M−1 delayed versions of the current overlap block by using M discrete Fourier transform (DFT) filters, wherein the current overlap block is of a size N greater than the size L, each generated discrete Fourier transform is of the size N and comprises N entries, the current overlap block comprises the samples of a current block and the N−L last consecutive samples of a directly previous block that was received directly before the current block, and each DFT filter of the M DFT filters is implemented by a fast Fourier transform (FFT) algorithm, of a size T smaller than the size N and by an interpolation algorithm;
• and
• filtering, by a compensation filter, the N entries of the generated M discrete Fourier transforms to generate an output discrete Fourier transform with N entries, wherein the compensation filter is implemented by a delay network and a linear combination algorithm.