Time-domain based composite modulation for spectrally efficient optical networks

Patent metadata

Field	Value
Publication number	US-9337928-B2
Application number	US-201414477435-A
Country	US
Kind code	B2
Filing date	Sep 4, 2014
Priority date	Nov 30, 2011
Publication date	May 10, 2016
Grant date	May 10, 2016

Abstract

Methods, systems, and apparatuses for time-based composite modulation of an optical carrier signal are provided. Time-based composite modulation includes determining a plurality of fixed time slots for the optical carrier signal, wherein the plurality of fixed time slots comprise a time-division-multiplexing frame. Determining a modulation format for each fixed time slot of the time-division-multiplexing frame, wherein a transport spectral efficiency of the modulation format determined for a first fixed time slot is different from a transport spectral efficiency of the modulation format determined for a second fixed time slot, and determining a number of binary bits for each fixed time slot of the time-division-multiplexing frame, wherein the number of binary bits for a fixed time slot is based on the modulation format determined for the fixed time slot.

First claim

We claim:

1. A method comprising:
receiving by an optical receiver an optical carrier signal;
determining a plurality of fixed time slots defining a time-division-multiplexing frame for the optical carrier signal;
determining a modulation format for each fixed time slot of the time-division-multiplexing frame;
determining a number of binary bits for each fixed time slot of the time-division-multiplexing frame; and
generating a frame sync marker for the time-division-multiplexing frame based on a determined modulation format.

2. The method of claim 1 , wherein the modulation format determined for a fixed time slot is one of a PDM-4QAM, PDM-8QAM, PDM-16QAM, PDM-32QAM and PDM-64QAM modulation format.

3. The method of claim 1 , wherein one or more time-division-multiplexing frames define a packet.

4. The method of claim 1 , wherein a transport spectral efficiency of the modulation format determined for a first fixed time slot is different from a transport spectral efficiency of the modulation format determined for a second fixed time slot.

5. The method of claim 1 , wherein the number of binary bits for a fixed time slot is based on the modulation format determined for the fixed time slot.

6. An apparatus comprising:
a processing module;
a non-transitory computer-readable medium storing computer program instructions for generating a compositely-modulated digital signal, which, when executed on the processing module, cause the processing module to perform operations comprising:
determining a plurality of fixed time slots defining a time-division-multiplexing frame for an optical carrier signal;
determining a modulation format for each fixed time slot of the time-division-multiplexing frame, wherein one or more time-division-multiplexing frames define a packet;
determining a number of binary bits for each fixed time slot of the time-division-multiplexing frame based on the modulation format determined for the fixed time slot to generate a compositely modulated digital signal;
a digital-to-analog converter, having a digital signal input coupled to an output of the processing module and providing an analog signal output, for converting the compositely-modulated digital signal into a compositely-modulated analog signal; and
an optical modulator, having an analog signal input coupled to the analog signal output of the digital-to-analog converter and providing an optical signal output, for generating a compositely-modulated optical signal based on the compositely-modulated analog signal.

7. The apparatus of claim 6 , wherein the modulation format determined for a fixed time slot is one of a PDM-4QAM, PDM-8QAM, PDM-16QAM, PDM-32QAM and PDM-64QAM modulation format.

8. The apparatus of claim 6 , further comprising computer program instructions causing the processing module to perform an operation for generating a frame sync marker for the time-division-multiplexing frame, wherein the frame sync marker indicates the modulation format determined for a fixed time slot of the time-division-multiplexing frame.

9. The apparatus of claim 6 , wherein the processing module is implemented by a CMOS-based digital signal processing chip.

10. The apparatus of claim 6 , wherein the processing module and the digital-to-analog converter are integrated on a CMOS-based chip.

11. A non-transitory computer-readable medium storing computer program instructions for generating a compositely-modulated digital signal, which, when executed on a processor, cause the processor to perform operations comprising:
receiving with an optical receiver an optical carrier signal;
determining a plurality of fixed time slots defining a time-division-multiplexing frame for an optical carrier signal;
determining a modulation format for each fixed time slot of the time-division-multiplexing frame;
determining a number of binary bits for each fixed time slot of the time-division-multiplexing frame; and
generating a frame sync marker for the time-division-multiplexing frame based on a determined modulation format.

12. The non-transitory computer-readable medium of claim 11 wherein the modulation format determined for a fixed time slot is one of a PDM-4QAM, PDM-8QAM, PDM-16QAM, PDM-32QAM and PDM-64QAM modulation format.

13. The non-transitory computer-readable medium of claim 11 , wherein one or more time-division-multiplexing frames define a packet.

14. The non-transitory computer-readable medium of claim 11 , wherein a transport spectral efficiency of the modulation format determined for a first fixed time slot is different from a transport spectral efficiency of the modulation format determined for a second fixed time slot.

15. The non-transitory computer-readable medium of claim 11 , wherein the number of binary bits for a fixed time slot is based on the modulation format determined for the fixed time slot.

Assignees

• At & T Ip I Lp

Inventors

• Zhou Xiang
• Magill Peter

Classifications

• H04B10/5161

  Combination of different modulation schemes · CPC title

• H04B10/116 Primary

  Visible light communication · CPC title

• H04J14/08 Primary

  Time-division multiplex systems · CPC title

• H04J3/0605

  Special codes used as synchronising signal · CPC title

• H04B10/516

  Details of coding or modulation · CPC title