Optical transmission method and optical receiver apparatus for determining received symbols from a received electrical signal using an indication of a nonlinear impulse response of the direct detection and without performing equalization following the direct detection

Patent metadata

Field	Value
Publication number	US-10826615-B2
Application number	US-201616461036-A
Country	US
Kind code	B2
Filing date	Dec 2, 2016
Priority date	Dec 2, 2016
Publication date	Nov 3, 2020
Grant date	Nov 3, 2020

Abstract

An optical transmission method ( 10 ) comprising steps of receiving ( 12 ) a communication signal comprising symbols for transmission. The method comprises performing ( 16 ) linear amplitude modulation of an optical carrier with the communication signal to generate an amplitude modulated optical carrier. The method comprises performing low-pass filtering ( 14 ) to reduce a bandwidth of the symbols to less than a Nyquist bandwidth of the symbols. The method comprises transmitting ( 18 ) the amplitude modulated optical carrier. The method further comprises receiving ( 20 ) the amplitude modulated optical carrier following transmission and performing direct detection of the received amplitude modulated optical carrier to generate a received electrical signal; and determining ( 22 ) received symbols from the received electrical signal using an indication of a nonlinear impulse response of the direct detection.

First claim

The invention claimed is:

1. An optical transmission method comprising:
receiving a communication signal comprising symbols for transmission;
performing amplitude modulation of an optical carrier with the communication signal to generate an amplitude-modulated optical carrier;
performing low-pass filtering to reduce a bandwidth of the amplitude-modulated optical carrier to less than a Nyquist bandwidth of the symbols;
transmitting the amplitude-modulated optical carrier;
receiving the amplitude-modulated optical carrier following transmission and performing direct detection of the received amplitude-modulated optical carrier to generate a received electrical signal; and
determining received symbols from the received electrical signal using an indication of a nonlinear impulse response of the direct detection and without performing equalization following the direct detection, wherein the indication of the nonlinear impulse response comprises Volterra series kernel coefficients of the nonlinear impulse response.

2. The method of claim 1 , wherein the indication of the nonlinear impulse response is based on two consecutive transmitted symbols.

3. The method of claim 1 , further comprising encoding the symbols using an error correcting code that enables a maximum achievable spectral efficiency for the amplitude modulation and the direct detection, wherein the amplitude-modulated carrier is generated based on the encoded symbols.

4. The method of claim 3 , wherein determining received symbols comprises performing iterative decoding of the received electrical signal based on the indication of the nonlinear impulse response and the error correcting code used to encode the symbols.

5. An optical receiver apparatus for an optical transmission system, the optical receiver apparatus comprising:
a photodiode configured to:
receive an amplitude-modulated optical carrier, wherein the amplitude-modulated optical carrier carries a communication signal comprising symbols and has a bandwidth less than a Nyquist bandwidth of the symbols, and
perform direct detection of the received amplitude-modulated optical carrier to generate a received electrical signal; and

a symbol determination apparatus configured to determine received symbols from the received electrical signal using an indication of a nonlinear impulse response of the photodiode and without performing equalization following the direct detection, wherein the indication of the nonlinear impulse response comprises Volterra series kernel coefficients of the nonlinear impulse response.

6. The optical receiver apparatus of claim 5 , wherein the indication of the nonlinear impulse response is based on two consecutive transmitted symbols.

7. The optical receiver apparatus of claim 5 , wherein:
the symbols are encoded with an error correcting code that enables a maximum achievable spectral efficiency for the amplitude modulation; and
the symbol determination apparatus comprises an iterative decoding apparatus configured to perform iterative decoding of the received electrical signal based on the indication of the nonlinear impulse response and the error correcting code used to encode the symbols, thereby determining the received symbols.

8. The optical receiver apparatus of claim 7 , wherein the symbol determination apparatus further comprises a kernel estimation apparatus configured to generate Volterra series kernel coefficients comprising the non-linear impulse response.

9. The optical receiver apparatus of claim 8 , wherein the Volterra series kernel coefficients are used by the iterative decoding apparatus to determine the received symbols.

10. A method of receiving an amplitude modulated optical carrier carrying a communication signal comprising symbols and having a bandwidth less than a Nyquist bandwidth of the symbols, the method comprising:
performing direct detection of the received amplitude modulated optical carrier to generate a received electrical signal; and
determining received symbols from the received electrical signal using an indication of a nonlinear impulse response of the direct detection and without performing equalization following the direct detection,
wherein determining the received symbols comprises:
generating Volterra series kernel coefficients comprising the non-linear impulse response; and
iteratively decoding the received electrical signal based on the Volterra series kernel coefficients and an error correcting code used to encode the symbols.

11. An optical receiver for receiving an amplitude modulated optical carrier carrying a communication signal, the communication signal comprising symbols and having a bandwidth less than a Nyquist bandwidth of the symbols, the optical receiver comprising processing circuitry configured to control operations corresponding to the method of claim 10 .

Assignees

• Ericsson Telefon Ab L M

Inventors

• Cavaliere Fabio
• Malacarne Antonio
• Foggi Tommaso
• Fresi Francesco
• Meloni Gianluca
• Poti Luca

Classifications

• H04B10/25

  Arrangements specific to fibre transmission · CPC title

• H04B10/541 Primary

  Digital intensity or amplitude modulation · CPC title

• H04B10/695

  Arrangements for optimizing the decision element in the receiver, e.g. by using automatic threshold control · CPC title

• H04B10/516 Primary

  Details of coding or modulation · CPC title