Hybrid TDM/WDM demultiplexing in low duty cycle optical transmission systems
AssigneeLucent Technologies Inc.
InventorsBrandon C. Collings, Howard R. Stuart
Life of this patent
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Abstract
A method and apparatus for preparing groups of low duty cycle WDM transmission channels such that each group can be demultiplexed either via conventional WDM (e.g., by optically filtering each channel and receiving that channel at its line rate) or via TDM (e.g., directing an entire group of WDM channels onto a signal higher speed detector, receiving them all and demultiplexing the channels in a temporal (electronic) domain).
Claims31
Apparatus, comprising:
- N modulators, for modulating N data streams onto respective wave division multiplex (WDM) channels to form a group of WDM channels, said WDM channels having a spacing of Δλ, where N is an integer;
- at least N−1 delay elements, for delaying respective WDM channels such that each adjacent WDM channel is temporally offset from an adjacent channel by an integer multiple of 1 Nf ,
- where f is the maximum bitrate of said N data streams;
- and
- a combiner, for combining said temporally offset WDM channels.
Apparatus for processing a signal including a plurality of wave division multiplex (WDM) channel groups, each of said WDM channel groups comprising N data streams modulated onto N respective WDM channels having a spacing of Δλ, each WDM channel being temporally offset from an adjacent WDM channel by an integer multiple of 1 Nf ,
- where N is an integer and f is the maximum bitrate of said N data streams, said apparatus comprising:
- an optical demultiplexer, for extracting at least one WDM channel group from said signal;
- a detector, for receiving said extracted WDM channel group and responsively providing a bit-interleaved time division multiplex (TDM) stream including N respective data streams;
- and
- an electronic demultiplexer, for demultiplexing at least one of said N respective data streams from said bit-interleaved TDM stream.
A method, comprising the steps of:
- generating M wave division multiplex (WDM) channels being spaced by Δλ, where M is an integer;
- grouping said WDM channels into at least one channel group comprising N WDM channels, each adjacent WDM channel in said at least one channel group being temporally offset from an adjacent channel by an integer multiple of 1 Nf ,
- where f is the maximum bitrate of said WDM channels and N is an integer;
- and
- combining, into an output signal, said N WDM channels forming said at least one channel group.
Method for processing a signal including a plurality of wave division multiplex (WDM) channel groups, each of said WDM channel groups comprising N data streams modulated onto N respective WDM channels having a spacing of Δλ, each WDM channel being temporally offset from an adjacent WDM channel by an integer multiple of 1 Nf ,
- where N is an integer and f is the maximum bitrate of said N data streams, said method comprising the steps of:
- extracting, using an optical demultiplexer, at least one WDM channel group from said signal;
- converting, using an optical to electrical detector, said extracted WDM channel group to a bit-interleaved time division multiplex (TDM) stream including N respective data streams;
- and
- demultiplexing at least one of said N respective data streams from said bit-interleaved TDM stream.
A computer readable medium having computer executable instructions for performing steps comprising:
- generating M wave division multiplex (WDM) channels being spaced by Δλ, where M is an integer;
- grouping said WDM channels into at least one channel group comprising N WDM channels, each adjacent WDM channel in said at least one channel group being temporally offset from an adjacent channel by an integer multiple of 1 Nf ,
- where f is the maximum bitrate of said WDM channels and N is an integer;
- and
- combining, into an output signal, said N WDM channels forming said at least one channel group.
Dependencies are inferred from the claim text.