Optical: systems and elements – Deflection using a moving element – Using a periodically moving element
Reexamination Certificate
1998-03-31
2001-04-24
Negash, Kinfe-Michael (Department: 2633)
Optical: systems and elements
Deflection using a moving element
Using a periodically moving element
C359S199200, C359S199200, C359S199200
Reexamination Certificate
active
06222653
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical transmission device comprising a plurality of nodes connected to each other to form a ring structure. In particular, the present invention relates to an optical transmission device having a ring structure using wavelength division multiplexing technology (WDM).
2. Description of the Related Art
A conventional optical transmission device comprising a plurality of nodes connected to each other to form a ring structure is described as the conventional art with reference to FIG.
16
.
FIG. 16
is a block diagram for illustrating an exemplary structure of an optical transmission device having a ring structure comprising m nodes, the respective nodes performs optical wavelength division multiplexing of wavelengths 1 to n to transmit optical signals.
In
FIG. 16
,
901
-
1
to
901
-m represent optical insertion division nodes,
902
-
1
to
902
-
4
represent transmission line optical fibers (
902
-
1
: counter-clockwise working (or primary) operation system,
902
-
2
: clockwise working operation system,
902
-
3
: counter-clockwise stand-by (or spare) system, and
902
-
4
: clockwise stand-by system,
951
represents an optical pre-amplifier (pre-optical amplifier),
952
represents a wavelength division section,
953
represents wavelength multiplexing section,
954
represents an optical booster amplifier (booster optical amplifier),
955
represents an optical pre-amplifier,
956
represents a wavelength division section,
957
represents a wavelength multiplexing section,
958
represents an optical booster amplifier,
959
represents an optical pre-amplifier,
960
represents a wavelength division section,
961
represents a wavelength multiplexing section,
962
represents an optical booster amplifier,
963
represents an optical amplifier,
964
represents a wavelength division section,
965
represents a wavelength multiplexing section,
966
represents an optical booster amplifier,
967
-
1
to
967
-n represent insertion division (ADM) devices,
971
to
974
represent high speed signal reception interface sections,
975
to
978
represent high speed signal transmission interface sections,
979
represents a cross connector section, and
980
represents a low speed signal interface section.
In
FIG. 16
, m nodes are connected to form a ring with a total of four transmission line optical fibers, where two of the lines comprise a bi-directional working (or primary) operation system, and where the other two of the lines comprise a bi-directional stand-by (or backup) operation system. Each node transmits a wavelength division multiplexed (WDM) optical signal having n wavelengths of &lgr;1 to &lgr;n to the above-mentioned four optical fiber transmission lines respectively, and each node receives the wavelength division multiplexed optical signal having n wavelengths of &lgr;1 to &lgr;n from the above-mentioned four optical fiber transmission lines.
Next, an operation performed in each node of the conventional optical transmission device having a ring structure as described above is described herein under.
The optical signal received from the counter-clockwise operation system is amplified by the optical pre-amplifier
951
, and divided into n wavelength components having wavelengths of &lgr;1 to &lgr;n in the wavelength division section
952
. The wavelength-divided n optical signals having wavelengths of &lgr;1 to &lgr;n are inputted to ADM devices
967
-
1
to
967
-n respectively. In detail, the optical signal having a wavelength of &lgr;1 is inputted to the ADM device
967
-
1
, the optical signal having a wavelength of &lgr;2 is inputted to the ADM device
967
-
2
, and the optical signal having a wavelength &lgr;n is inputted to the ADM device
967
-n.
n optical signals having wavelengths of &lgr;1 to &lgr;n are outputted from the respective ADM devices
967
-
1
to
967
-n. In detail, the optical signal having a wavelength of &lgr;1 is outputted from the ADM device
967
-
1
, the optical signal having a wavelength of &lgr;2 is outputted from the ADM device
967
-
2
, and the optical signal having a wavelength &lgr;n is outputted from the ADM device
967
-n. n optical signals having wavelengths of &lgr;1 to &lgr;n are subjected to wavelength division multiplexing operation in the wavelength multiplexing section
953
to form a single optical signal. The single optical signal is amplified by the optical booster amplifier
954
, and then sent out to the counter-clockwise operation optical fiber transmission line. The optical signal that is transmitted/received through other transmission lines, namely, the clockwise working operation system
902
-
2
, counter-clockwise stand-by system
902
-
3
, and clockwise stand-by system
902
-
4
, is subjected to a multiplexing division (or separation) operation involving wavelengths of &lgr;1 to &lgr;n like the above-mentioned operation.
In
FIG. 16
, the optical pre-amplifier
955
, wavelength division section
956
, wavelength multiplexing section
957
, and optical booster amplifier
958
are applied to the clockwise working operation system, the optical pre-amplifier
959
, wavelength division section
960
, wavelength multiplexing section
961
, and optical booster amplifier
962
are applied to the counter-clockwise stand-by system, and the optical pre-amplifier
963
, wavelength division section
964
, wavelength multiplexing section
965
, and optical booster amplifier
966
are applied to the clockwise stand-by system.
Operation in the ADM device
967
-
1
is described herein under.
Four optical signals having wavelength of &lgr;1 inputted from the wavelength division sections
952
,
956
,
960
, and
964
are respectively subjected to optical/electric conversion, overhead signal termination, and time-division separation in high speed signal reception interface sections (HSRx)
971
to
974
. Afterwards, the optical signals are inputted to the cross connector section
979
as electric data signals. Electric signals are inputted from the cross connector section
979
to the high speed signal transmission interface sections (HSTx)
975
to
978
, where the electric signals are subjected to time-division multiplexing, overhead signal insertion, and electric/optical conversion operation, and then optical signals having wavelength of &lgr;1 are outputted to the wavelength multiplexing section
953
,
957
,
961
, and
965
. The cross connector section
979
functions to connect four pairs of electric data signals inputted from the high speed reception interface sections (HSRx)
971
to
974
selectively to four pairs of electric signals to be outputted to the high speed signal transmission interface sections
975
to
978
depending on the failure condition of transmission lines in the ring network, and functions to division-connect partially or entirely the input electric data signal to the low speed signal interface section
980
and to insert the signal from the low speed signal interface section
980
in an output data signal.
Next, recovery operation performed when the transmission line of the conventional ring optical transmission device shown in
FIG. 16
experiences a failure is described.
FIG. 17
is a set of diagrams for illustrating the recovery operation.
In FIG.
17
(
a
) during working (or normal) operation, data signals are communicated through the two operation transmission lines between the node
2
and node
5
. In node
2
and node
5
, the data signal is inputted from/outputted to the low speed signal interface section in each node, and the cross connector section sets the path.
Recovery operation performed when two operation transmission lines experiences a failure between the node
2
and node
3
is shown in FIG.
17
(
b
). In this case, in the node
2
, the cross connector section changes connection from the path that a data signal is allowed to be communicated through the operation transmission line side between the node
3
and node
2
for insertion division, to the path that a data signal is allowed t
Foley & Lardner
NEC Corporation
Negash Kinfe-Michael
LandOfFree
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