U.S. patent application number 16/161165 was filed with the patent office on 2020-04-16 for optimized colorless, directionless, and contentionless roadm in a module.
The applicant listed for this patent is Ciena Corporation. Invention is credited to Jean-Luc Archambault, Paul Chedore.
Application Number | 20200119829 16/161165 |
Document ID | / |
Family ID | 70160599 |
Filed Date | 2020-04-16 |
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United States Patent
Application |
20200119829 |
Kind Code |
A1 |
Chedore; Paul ; et
al. |
April 16, 2020 |
OPTIMIZED COLORLESS, DIRECTIONLESS, AND CONTENTIONLESS ROADM IN A
MODULE
Abstract
A Reconfigurable Optical Add/Drop Multiplexer (ROADM) node with
a Colorless, Directionless, and Contentionless (CDC) architecture,
targeting smaller degree nodes, includes an integrated ROADM degree
and add/drop module having M common input and output ports and N
add/drop input and output ports, wherein the integrated ROADM
degree and add/drop module is formed by an M.times.N demultiplexer
Contentionless Wavelength Selective Switch (CWSS) and an M.times.N
multiplexer CWSS; and X degree modules, each having an input and
output port connected to common ports of the integrated ROADM
degree and add/drop module, a first set of ports of the N add/drop
input and output ports are connected for degree-to-degree
connectivity and a second set of ports of the N add/drop input and
output ports are utilized for local add/drop, such that the
integrated module provides both the degree-to-degree connectivity
and the local add/drop.
Inventors: |
Chedore; Paul; (Ottawa,
CA) ; Archambault; Jean-Luc; (Ottawa, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ciena Corporation |
Hanover |
MD |
US |
|
|
Family ID: |
70160599 |
Appl. No.: |
16/161165 |
Filed: |
October 16, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04J 14/0217 20130101;
H04Q 2011/0016 20130101; H04J 14/0212 20130101; H04Q 11/0005
20130101 |
International
Class: |
H04J 14/02 20060101
H04J014/02; H04Q 11/00 20060101 H04Q011/00 |
Claims
1. A Reconfigurable Optical Add/Drop Multiplexer (ROADM) node with
a Colorless, Directionless, and Contentionless (CDC) architecture,
the ROADM node comprising: an integrated ROADM degree and add/drop
module having M common input and output ports and N add/drop input
and output ports, wherein the integrated ROADM degree and add/drop
module is formed by an M.times.N demultiplexer Contentionless
Wavelength Selective Switch (CWSS) and an M.times.N multiplexer
CWSS, M and N are integers; and X degree modules, X is an integer
and represents a number of degrees of the ROADM node, each having
an input and output port connected to associated common ports of
the integrated ROADM degree and add/drop module, wherein a first
set of ports of the N add/drop input and output ports are connected
between the demultiplexer CWSS and the multiplexer CWSS for
degree-to-degree connectivity and a second set of ports of the N
add/drop input and output ports are utilized for local add/drop of
channels, such that the integrated ROADM degree and add/drop module
provides both the degree-to-degree connectivity and the local
add/drop of channels utilizing the demultiplexer CWSS and the
multiplexer CWSS, and wherein the first set of ports is X*(X-1)
input and output ports and the second set of ports is N-X*(X-1)
input and output ports.
2. The ROADM node of claim 1, wherein X.ltoreq.4.
3. (canceled)
4. The ROADM node of claim 1, wherein M-X input and output ports of
the M common input and output ports are unequipped.
5. The ROADM node of claim 1, wherein the first set of ports
comprise input and output ports for each degree to connect to every
other degree.
6. The ROADM node of claim 1, wherein the demultiplexer CWSS and
the multiplexer CWSS each comprise: M 1.times.N Wavelength
Selective Switches (WSSs) each connected to one of M common ports;
and N M-1 selector switches each connected to each of the M
1.times.N WSSs and connected to N add/drop ports.
7. The ROADM node of claim 6, wherein the M 1.times.N WSSs are each
formed using Liquid Crystal On Silicon (LCOS) and the N M.times.1
selector switches are formed using Microelectromechanical systems
(MEMS) mirrors or a Planar Lightwave Circuit (PLC).
8. The ROADM node of claim 1, wherein the X degree modules each
comprise a pre-amplifier, a post-amplifier, and an Optical Service
Channel (OSC) module.
9. An integrated Reconfigurable Optical Add/Drop Multiplexer
(ROADM) degree and add/drop module with a Colorless, Directionless,
and Contentionless (CDC) architecture, comprising: M common input
and output ports; and N add/drop input and output ports, an
M.times.N demultiplexer Contentionless Wavelength Selective Switch
(CWSS) and an M.times.N multiplexer CWSS, M and N are integers,
configured to optically connect the M common input and output ports
and the N add/drop input and output ports, wherein the integrated
ROADM degree and add/drop module is utilized in an X degree ROADM
node, X is an integer, wherein a first set of ports of the N
add/drop input and output ports are connected between the
demultiplexer CWSS and the multiplexer CWSS for degree-to-degree
connectivity and a second set of ports of the N add/drop input and
output ports are utilized for local add/drop of channels, such that
the integrated ROADM degree and add/drop module provides both the
degree-to-degree connectivity and the local add/drop of channels
utilizing the demultiplexer CWSS and the multiplexer CWSS, and
wherein the first set of ports is X*(X-1) input and output ports
and the second set of ports is N-X*(X-1) input and output
ports.
10. The integrated ROADM degree and add/drop module of claim 9,
wherein X.ltoreq.4.
11. (canceled)
12. The integrated ROADM degree and add/drop module of claim 9,
wherein M-X input and output ports of the M common input and output
ports are unequipped.
13. The integrated ROADM degree and add/drop module of claim 9,
wherein the first set of ports comprise input and output ports for
each degree to connect to every other degree.
14. The integrated ROADM degree and add/drop module of claim 9,
wherein the demultiplexer CWSS and the multiplexer CWSS each
comprise: M 1.times.N Wavelength Selective Switches (WSSs) each
connected to one of M common ports; and N M.times.1 selector
switches each connected to each of the M 1.times.N WSSs and
connected to N add/drop ports.
15. The integrated ROADM degree and add/drop module of claim 14,
wherein the M 1.times.N WSSs are each formed using Liquid Crystal
On Silicon (LCOS) and the N M.times.1 selector switches are formed
using Microelectromechanical systems (MEMS) mirrors or a Planar
Lightwave Circuit (PLC).
16. The integrated ROADM degree and add/drop module of claim 9,
wherein each of X of the M common input and output ports are each
connected to an associated degree module each comprising a
pre-amplifier, a post-amplifier, and an Optical Service Channel
(OSC) module.
17. (canceled)
18. (canceled)
19. (canceled)
20. (canceled)
21. An integrated Reconfigurable Optical Add/Drop Multiplexer
(ROADM) degree and add/drop module with a Colorless, Directionless,
and Contentionless (CDC) architecture, comprising: M common input
and output ports; and N add/drop input and output ports, an
M.times.N demultiplexer Contentionless Wavelength Selective Switch
(CWSS) and an M.times.N multiplexer CWSS, M and N are integers,
configured to optically connect the M common input and output ports
and the N add/drop input and output ports, wherein the integrated
ROADM degree and add/drop module is utilized in an X degree ROADM
node, X is an integer, wherein a first set of ports of the N
add/drop input and output ports are connected between the
demultiplexer CWSS and the multiplexer CWSS for degree-to-degree
connectivity and a second set of ports of the N add/drop input and
output ports are utilized for local add/drop of channels, such that
the integrated ROADM degree and add/drop module provides both the
degree-to-degree connectivity and the local add/drop of channels
utilizing the demultiplexer CWSS and the multiplexer CWSS, and.
wherein the demultiplexer CWSS and the multiplexer CWSS each
include M 1.times.N Wavelength Selective Switches (WSSs) each
connected to one of M common ports, and N M.times.1 selector
switches each connected to each of the M 1.times.N WSSs and
connected to N add/drop ports.
22. The integrated ROADM degree and add/drop module of claim 21,
wherein X.ltoreq.4.
23. The integrated ROADM degree and add/drop module of claim 21,
wherein M-X input and output ports of the M common input and output
ports are unequipped.
24. The integrated ROADM degree and add/drop module of claim 21,
wherein the first set of ports comprise input and output ports for
each degree to connect to every other degree.
25. The integrated ROADM degree and add/drop module of claim 21,
wherein the M 1.times.N WSSs are each formed using Liquid Crystal
On Silicon (LCOS) and the N M.times.1 selector switches are formed
using Microelectromechanical systems (MEMS) mirrors or a Planar
Lightwave Circuit (PLC).
26. The integrated ROADM degree and add/drop module of claim 21,
wherein each of X of the M common input and output ports are each
connected to an associated degree module each comprising a
pre-amplifier, a post-amplifier, and an Optical Service Channel
(OSC) module.
Description
FIELD OF THE DISCLOSURE
[0001] The present disclosure generally relates to optical
networking. More particularly, the present disclosure relates to
systems and methods for an optimized Colorless, Directionless, and
Contentionless (CDC) Reconfigurable Optical Add/Drop Multiplexer
(ROADM) in an integrated module.
BACKGROUND OF THE DISCLOSURE
[0002] Optical networks utilize Reconfigurable Optical Add-Drop
Multiplexers (ROADMs) to realize selective and reconfigurable
add/drop of wavelengths or spectrum locally and between various
degrees. ROADMs generally utilize Wavelength Selective Switches
(WSSs) in different configurations. Flexibility in add/drop
requirements has led to so-called colorless, directionless, and
optionally contentionless add/drop multiplexer structures, such as
in ROADM devices, nodes, architectures, and structures. A colorless
add/drop device supports any wavelength or spectral occupancy/band
being added to any port of an add/drop device, i.e., ports are not
wavelength specific. A directionless add/drop device supports any
port being directed to any degree. Finally, a contentionless
add/drop device supports multiple instances of the same channel
(wavelength) in the same device (albeit to different degrees). A
colorless, directionless add/drop device can be referred to as a CD
device, and a colorless, directionless, and contentionless add/drop
device can be referred to as a CDC device.
[0003] CDC ROADM deployments are common and offer the most
flexibility, albeit at higher costs and equipment requirements. Of
note, conventional CDC configurations are less cost effective for
smaller degree nodes. For this reason, network operators typically
opt for CD or Colorless Direct Attach (CDA) configurations for
smaller degree nodes (e.g., four or fewer degrees). It would be
advantageous to provide a configuration which supports CDC in
smaller degree and add/drop nodes with lower costs and equipment
requirements.
BRIEF SUMMARY OF THE DISCLOSURE
[0004] In an embodiment, a Reconfigurable Optical Add/Drop
Multiplexer (ROADM) node with a Colorless, Directionless, and
Contentionless (CDC) architecture includes an integrated ROADM
degree and add/drop module having M common input and output ports
and N add/drop input and output ports, wherein the integrated ROADM
degree and add/drop module is formed by an M.times.N demultiplexer
Contentionless Wavelength Selective Switch (CWSS) and an M.times.N
multiplexer CWSS, M and N are integers; and X degree modules, X is
an integer and represents a number of degrees of the ROADM node,
each having an input and output port connected to associated common
ports of the integrated ROADM degree and add/drop module, wherein a
first set of ports of the N add/drop input and output ports are
connected between the demultiplexer CWSS and the multiplexer CWSS
for degree-to-degree connectivity and a second set of ports of the
N add/drop input and output ports are utilized for local add/drop
of channels, such that the integrated ROADM degree and add/drop
module provides both the degree-to-degree connectivity and the
local add/drop of channels utilizing the demultiplexer CWSS and the
multiplexer CWSS. X can be .ltoreq.4.
[0005] The first set of ports can be X*(X-1) input and output ports
and the second set of ports can be N-X*(X-1) input and output
ports. M-X input and output ports of the M common input and output
ports can be unequipped. The first set of ports can include input
and output ports for each degree to connect to every other degree.
The demultiplexer CWSS and the multiplexer CWSS each can include M
1.times.N Wavelength Selective Switches (WSSs) each connected to
one of M common ports; and N M.times.1 selector switches each
connected to each of the M 1.times.N WSSs and connected to N
add/drop ports. The M 1.times.N WSSs can be each formed using
Liquid Crystal On Silicon (LCOS) and the N M.times.1 selector
switches can be formed using Microelectromechanical systems (MEMS)
mirrors or a Planar Lightwave Circuit (PLC). The X degree modules
each can include a pre-amplifier, a post-amplifier, and an Optical
Service Channel (OSC) module.
[0006] In another embodiment, an integrated Reconfigurable Optical
Add/Drop Multiplexer (ROADM) degree and add/drop module with a
Colorless, Directionless, and Contentionless (CDC) architecture
includes M common input and output ports; and N add/drop input and
output ports, an M.times.N demultiplexer Contentionless Wavelength
Selective Switch (CWSS) and an M.times.N multiplexer CWSS, M and N
are integers, configured to optically connect the M common input
and output ports and the N add/drop input and output ports, wherein
the integrated ROADM degree and add/drop module is utilized in an X
degree ROADM node, X is an integer, and wherein a first set of
ports of the N add/drop input and output ports are connected
between the demultiplexer CWSS and the multiplexer CWSS for
degree-to-degree connectivity and a second set of ports of the N
add/drop input and output ports are utilized for local add/drop of
channels, such that the integrated ROADM degree and add/drop module
provides both the degree-to-degree connectivity and the local
add/drop of channels utilizing the demultiplexer CWSS and the
multiplexer CWSS. X can be .ltoreq.4.
[0007] The first set of ports can be X*(X-1) input and output ports
and the second set of ports can be N-X*(X-1) input and output
ports. M-X input and output ports of the M common input and output
ports can be unequipped. The first set of ports can include input
and output ports for each degree to connect to every other degree.
The demultiplexer CWSS and the multiplexer CWSS each can include M
1.times.N Wavelength Selective Switches (WSSs) each connected to
one of M common ports; and N M.times.1 selector switches each
connected to each of the M 1.times.N WSSs and connected to N
add/drop ports. The M 1.times.N WSSs can be each formed using
Liquid Crystal On Silicon (LCOS) and the N M.times.1 selector
switches can be formed using Microelectromechanical systems (MEMS)
mirrors or a Planar Lightwave Circuit (PLC). Each of X of the M
common input and output ports can be each connected to an
associated degree module each including a pre-amplifier, a
post-amplifier, and an Optical Service Channel (OSC) module.
[0008] In a further embodiment, a method includes providing an
integrated Reconfigurable Optical Add/Drop Multiplexer (ROADM)
degree and add/drop module with a Colorless, Directionless, and
Contentionless (CDC) architecture, including M common input and
output ports; and N add/drop input and output ports, an M.times.N
demultiplexer Contentionless Wavelength Selective Switch (CWSS) and
an M.times.N multiplexer CWSS, M and N are integers, configured to
optically connect the M common input and output ports and the N
add/drop input and output ports, wherein the integrated ROADM
degree and add/drop module is utilized in an X degree ROADM node, X
is an integer, and wherein a first set of ports of the N add/drop
input and output ports are connected between the demultiplexer CWSS
and the multiplexer CWSS for degree-to-degree connectivity and a
second set of ports of the N add/drop input and output ports are
utilized for local add/drop of channels, such that the integrated
ROADM degree and add/drop module provides both the degree-to-degree
connectivity and the local add/drop of channels utilizing the
demultiplexer CWSS and the multiplexer CWSS. The method can further
include providing X degree modules each having an input and output
port connected to associated common ports of the integrated ROADM
degree and add/drop module. X can be .ltoreq.4. The first set of
ports can be X*(X-1) input and output ports and the second set of
ports can be N-X*(X-1) input and output ports.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The present disclosure is illustrated and described herein
with reference to the various drawings, in which like reference
numbers are used to denote like system components/method steps, as
appropriate, and in which:
[0010] FIG. 1 is a block diagram of an example four degree ROADM
node utilizing multiple modules to form the degrees and the local
add/drop;
[0011] FIG. 2 is a block diagram of an optimized ROADM node
utilizing a single module to form the degrees and the local
add/drop;
[0012] FIG. 3 is a block diagram of a contentionless WSS utilized
in the optimized ROADM node;
[0013] FIG. 4 is a block diagram of nodal connectivity associated
with the ROADM degree and add/drop module and two Contentionless
Wavelength Selective Switches (CWSSs) in the optimized ROADM node
of FIG. 2;
[0014] FIG. 5 is a block diagram of module connectivity between the
ROADM degree and add/drop module and the amplifier modules in the
optimized ROADM node of FIG. 2;
[0015] FIG. 6 is a block diagram of a CWSS on a demultiplexer side
illustrating degree routing; and
[0016] FIG. 7 is a block diagram of module connectivity in an
optimized ROAM node which includes two ROADM degree and add/drop
modules for redundancy and/or increased port count.
DETAILED DESCRIPTION OF THE DISCLOSURE
[0017] In various embodiments, the present disclosure relates to an
optimized Colorless, Directionless, and Contentionless (CDC)
Reconfigurable Optical Add/Drop Multiplexer (ROADM) in an
integrated module. Specifically, the proposed CDC ROADM described
herein provides a small CDC architecture within a single module,
e.g., supporting a four degree or less ROADM node. Variously, the
CDC architecture proposed herein utilizes a same Wavelength
Selective Switch (WSS) module for both degree connectivity and for
local add/drop, enabling a single module to support a cost-reduced
CDC ROADM. Thus, the switching elements of a CDC architecture is
self-contained in the single module, providing cost reduction, less
equipment, reduced power consumption, etc. versus a conventional,
multi-module CDC architecture. The CDC architecture proposed herein
is ideal for smaller degree nodes.
Conventional CDC ROADM Architecture
[0018] FIG. 1 is a block diagram of an example four degree ROADM
node 100 utilizing multiple modules 102, 104, 106 to form the
degrees and the local add/drop. Specifically, the ROADM node 100
includes four-degree modules 102A, 102B, 102C, 102D, a Fiber
Interface Module (FIM) 104 for managing fiber connectivity between
the modules 102, 106, and a local add/drop module 106. The degree
modules 102A, 102B, 102C, 102D each include a Wavelength Selective
Switch (WSS) demultiplexer 110, a WSS multiplexer 112,
pre-amplifier 116, a post-amplifier 118, and an Optical Channel
Monitor (OCM) 114. The degree modules 102A, 102B, 102C, 102D can
further include an Optical Service Channel (OSC), and other
components. The FIM module 104 can be a passive device which
provides optical fiber connectivity between the degree modules
102A, 102B, 102C, 102D, between the degree modules 102A, 102B,
102C, 102D and the local add/drop module 106. The local add/drop
module 106 provides connectivity to local optical transceivers,
modems, etc. to the degrees via the degree modules 102A, 102B,
102C, 102D. The local add/drop module 106 includes a WSS 120 for
channel adds, a WSS 122 for channel drops, and amplifiers 124
(which can be optional).
[0019] The four-degree ROADM node 100 includes a CDC architecture
which is flexible, operationally simple, and future-proof. Any
wavelength can be added/dropped or expressed through any degree,
through software configuration. However, the CDC architecture
illustrated in the four degree ROADM node 100 has significant cost,
required equipment, and power consumption. Specifically, the
four-degree ROADM node 100 has eight WSS modules 110, 112 and two
WSS modules 120,122 for a total of 10 WSS modules.
Optimized CDC ROADM Architecture
[0020] Accordingly, embodiments are presented directed to an
optimized CDC ROADM architecture which reduces the equipment,
footprint, and cost/power associated with the four degree ROADM
node 100. FIG. 2 is a block diagram of an optimized ROADM node 200
utilizing a single module 202 to form the degrees and the local
add/drop degrees and local add/drop switching. Specifically, the
optimized ROADM node 200 provides the same CDC architecture as the
four-degree ROADM node 100 albeit with reduced equipment. The
optimized ROADM node 200 includes a ROADM degree and add/drop
module 202 which is a single module providing WSS functionality for
both degree-to-degree connectivity and for local add/drop. The
ROADM degree and add/drop module 202 provides the degree
functionality of the degree modules 102A, 102B, 102C, 102D.
Instead, the optimized ROADM node 200 includes amplifier modules
204A, 204B, 204C, 204D instead of the degree modules 102A, 102B,
102C, 102D. The amplifier module 204 includes a pre-amplifier 206,
a post-amplifier 208, and an OSC 210. Note, the amplifier modules
204 do not require WSS components as the degree modules 102
include. Accordingly, the amplifier modules 204 have reduced cost,
space, and power relative to the degree modules 102.
[0021] Note, the four-degree ROADM node 100 and the optimized ROADM
node 200 are both shown with four degrees for illustration
purposes. As described herein, the four-degree ROADM node 100 has a
total of 10 WSS modules whereas the optimized ROADM node 200
requires only 2 WSS modules, namely a contentionless WSS 250 (one
for the multiplexer and one for the demultiplexer). Those of
ordinary skill in the art will recognize the single module 202 can
be used to form other nodal architectures, i.e., one, two,
three-degrees. Also, the single module 202 can be used to form
larger degrees, i.e., five or more, at the expense of a reduction
in local add/drop. The proposed solution advantageously enables
implementation of smaller degree nodes with a CDC approach.
[0022] The four-degree ROADM node 100 can also include the OCM 114
to provide monitoring functionality. In an embodiment, the OCM 114
can be integrated in the single module 202. In another embodiment,
the OCM 114 can be in each of the amplifier modules 204A, 204B,
204C, 204D.
Contentionless WSS
[0023] FIG. 3 is a block diagram of a contentionless WSS (CWSS) 250
utilized in the optimized ROADM node 200. The CWSS 250 is utilized
to realize the CDC architecture. Previously, the CDC architecture
was formed through Multicast Switches (MCS). Advantageously, the
CWSS 250 has, relative to the MCS implementation of a CDC
architecture, a significantly lower loss, the potential to scale to
higher port counts, and channel filtering is built-in in the
multiplexing direction to reduce noise funneling. The systems and
methods herein utilize the CWSS 250 to realize the CDC architecture
in the optimized ROADM node 200. An example of the CWSS 250 is
described in Colbourne, P. D., McLaughlin, S., Murley, C., Gaudet,
S., & Burke, D. (2018, March), "Contentionless Twin 833 24 WSS
with Low Insertion Loss," in Optical Fiber Communication Conference
(pp. Th4A-1), Optical Society of America, the contents of which are
incorporated by reference herein.
[0024] The CWSS 250 includes an M-array of 1.times.N WSSs 252 and
an N-array of M.times.1 selector switches 254. The CWSS 250
requires two switching elements, namely the M-array of 1.times.N
WSS 252 and the N-array of M.times.1 selector switches 254 (whereas
the MCS has a single switching element with combiners/splitters).
Thus, the CWSS 250 can be referred to as an M.times.N device (M, N
are integers, such as 8.times.24, etc.).
[0025] The M ports connected to the 1.times.N WSSs 252 can be
referred to as common ports 256 of the CWSS 250 and each is
connected to a fully independent 1.times.N WSS 252, enabling
individual wavelengths to be routed independently to any of N
Add/Drop ports 258 connected to the M.times.1 selector switches
254. Each of the N Add/Drop ports 258 can be coupled to any common
port 256 of the CWSS 250 via the bank of M.times.1 selector
switches 254. Note that each add/drop port 258 can be connected to
only one common port 256 at one time (there is no wavelength
selectivity in the M.times.1 selector switches 254). The function
is similar to a multicast switch, but with 1.times.N splitters
replaced by 1.times.N WSS's. Up to M instances of a given
wavelength can be routed independently through the M.times.N CWSS
250 without contention.
[0026] In an embodiment, the CWSS 250 can be 8.times.24 (M=8, N=24)
and the 1.times.24 WSS's 252 can be implemented using Liquid
Crystal On Silicon (LCOS) phase modulator beam steering. One LCOS
panel can be sub-divided into several independent sections, to
control multiple independent WSS's within the same device, plus the
LCOS steering engine enables flexible spectrum operation with
variable channel widths. To minimize insertion loss, the 8.times.1
selector switches 254 can be implemented using an array of
Microelectromechanical systems (MEMS) mirrors (a Planar Lightwave
Circuit (PLC) design also possible). An advantage of MEMS mirrors
as the switch elements is high isolation, thus preventing
same-wavelength signals from different common ports 256 from
causing interference.
[0027] The foregoing description utilizes the CWSS 250 as an
8.times.26 device (M=8, N=26) for describing the implementation of
the ROADM degree and add/drop module 202. Those of ordinary skill
in the art will recognize that different values of M and N are
contemplated.
Single ROADM Degree and Add/Drop Module
[0028] FIG. 4 is a block diagram of nodal connectivity associated
with the ROADM degree and add/drop module 202 and two CWSSs 250 in
the optimized ROADM node 200. FIG. 5 is a block diagram of module
connectivity between the ROADM degree and add/drop module 202 and
the amplifier modules 204A, 204B, 204C, 204D in the optimized ROADM
node 200. Again, for illustration purposes, FIGS. 4 and 5
illustrate a four-degree configuration and other degree
configurations are also contemplated.
[0029] The present disclosure contemplates a single ROADM degree
and add/drop module 202 which performs the degree connectivity and
the local add/drop connectivity in a single, integrated module. The
ROADM degree and add/drop module 202 provides the functionality of
the local add/drop module 106 and the WSS demultiplexer 110 and the
WSS multiplexer 112 in the degree modules 102.
[0030] The single ROADM degree and add/drop module 202 includes two
CWSS 250 modules which are denoted as CWSS 250D for a demultiplexer
WSS and CWSS 250M for a multiplexer WSS, i.e., the single ROADM
degree and add/drop module 202 contains both the multiplexer and
demultiplexer WSS functions. In an embodiment, the CWSS 250D, 250M
can be a twin contentionless 8.times.26 WSS module. The CWSS 250D,
250M is generally designed to act as CDC multiplexer/demultiplexer
when used in combination with a high port count twin WSS on the
line side (such as the WSSs 120, 122 in FIG. 1). However, through
remapped internal connectivity, the CWSSs 250D, 250M are also
repurposed to provide a multi-degree CDC ROADM along with the
add/drop functionality.
[0031] FIG. 4 illustrates logical connectivity using the single
ROADM degree and add/drop module 202 to provide a four degree CDC
architecture and to locally add/drop 14 channels. The optimized
ROADM node 200 includes four degrees, labeled D1, D2, D3, D4. FIG.
4 is illustrated logically from right to left with the right side
showing node ingress via four pre-amplifiers 206, one for each
degree D1, D2, D3, D4, and each input into an associated common
port 256 of the CWSS 250D.
[0032] The CWSS 250D has ports 258, which are denoted as add/drop
ports 258A and express ports 258B. The add/drop ports 258A are used
for local add/drop 260 and the express ports 258B are used for
degree-to-degree connectivity 262. On the CWSS 250D, the add/drop
ports 258A are used for dropping channels from the degrees D1, D2,
D3, D4. The express ports 258B on the CWSS 250D connect to
respective express ports 258B on the CWSS 250M. For example, a
degree D1-D2 express port 258B on the CWSS 250D connects to a
corresponding degree D1-D2 express port 258B on the CWSS 250M, and
the like. The CWSS 250M also has add/drop ports 258A used for local
add/drop 260. On the CWSS 250M, the add/drop ports 258A are used
for adding channels locally to the degrees D1, D2, D3, D4.
[0033] Of note, an aspect of the proposed solution is the unique
connectivity between the express ports 258B on the CWSS 250D and
the express ports 258B on the CWSS 250M for the degree-to-degree
connectivity. Because the CWSS 250D, 250M uses MEMS for the
add/drop ports 258, e.g., the M.times.1 selector switches 254, the
CWSS 250D, 250M can only route spectrum from/to a specific degree.
As such, it is not possible to simply connect the multiplexer and
demultiplexer halves of a module and route traffic arbitrarily
between degrees.
[0034] For example, traffic incident on degree D1 has spectrum that
needs to be routed to degrees D2, D3, D4. Since the input to the
CWSS 250M module has a MEMs switch which selects a given degree
(stripe of LCOS), it is not possible to send all the express
traffic to one port. Express traffic from degree D1 needs to be
routable to an input dedicated to degree D2, D3, D4. FIG. 6 is a
block diagram of the CWSS 250D illustrating degree routing. Here,
degree D1 is input to a 1.times.N WSS 252A which steers light
towards a given output port's MEMs switch. As such, the express
ports 258B require a port for each degree, namely D1-D2, D1-D3,
etc.
[0035] For X degrees, X being an integer, the configuration of the
CWSS 250D, 250M requires X*(X-1) ports to route express traffic.
Thus, for four degrees, the optimized ROADM node 200 requires
4*(4-1)=12 port connections between the CWSS 250D and the CWSS 250M
halves of the module.
[0036] Assume the CWSS 250D, 250M are M.times.N devices (M, N are
integers, typically M<N, but not required) and there are X
degrees, X is an integer (X must be less than or equal to M), the
following provides the port numbers available for local
add/drop.
[0037] Number of the express ports 258B required for
degree-to-degree connectivity 262=X*(X-1).
[0038] The M common ports 256 on each of the CWSS 250D, 250M are
connected to the X degrees, and if M>X, these ports are
unequipped.
[0039] Number of the express ports 258B for the local add/drop
260=N-X*(X-1).
[0040] Assume the CWSS 250D, 250M are 8.times.26 (M=8, N=26), the
following table illustrates capabilities for a different number of
degrees (these numbers apply to one of the CWSS 250D, 250M):
TABLE-US-00001 TABLE 1 Example port counts for different degrees
and an 8 .times. 26 CWSS Number of Degrees Common ports 256
Add/drop ports 258 2 2 equipped; 6 unequipped 2 for
degree-to-degree connectivity 262 24 for local add/drop 260 3 3
equipped; 5 unequipped 6 for degree-to-degree connectivity 262 20
for local add/drop 260 4 4 equipped; 4 unequipped 12 for
degree-to-degree connectivity 262 14 for local add/drop 260 5 5
equipped; 3 unequipped 20 for degree-to-degree connectivity 262 6
for local add/drop 260
[0041] As seen in Table 1, the CWSS 250D, 250M in the optimized
ROADM node 200 provide reasonable add/drop counts for degrees four
and lower, at the expense of unused/unequipped common ports and at
a significantly lower cost, power, and footprint relative to the
CDC architecture of the four-degree ROADM node 100.
[0042] Of course, other values of M.times.N are contemplated. For
example, it is expected that N will increase, e.g., 26 to 40, etc.
This would enable more degrees, e.g., an 8.times.40 CWSS 250D, 250M
would enable the 5 degrees with 20 local add/drop 260. Thus, when N
is larger, it may be possible to deploy the optimized ROADM node
200 at higher degree nodes (e.g., 5 or more). In this manner, the
optimized ROADM node 200 may support the CDC architecture at all
nodes in a network.
[0043] FIG. 5 illustrates a module configuration for realizing the
optimized ROADM node 200 using the CWSS 250D, 250M. Of note, FIG. 5
has the same functionality as FIG. 1 albeit with less equipment and
the ROADM degree and add/drop module 202 for providing both local
add/drop 260 and degree-to-degree connectivity 262. From a hardware
perspective, the ROADM degree and add/drop module 202 can be a
rack-mountable module (e.g., 1-2 Rack Units (RU) high) or circuit
pack inserted into a shelf with 2M common ports 270 and 2N add/drop
ports 272. The ports 270, 272 are optical ports configured for an
optical fiber, patch cord, etc. The ROADM degree and add/drop
module 202 includes both the CWSS 250D, 250M and thus has 2M common
ports 270 and 2N add/drop ports 272.
[0044] In this example, four degrees and 8.times.26 CWSS 250D,
250M, the 2M common ports 270 include 8 ports on the CWSS 250D and
8 ports on the CWSS 250M, four of which on each are
unused/unequipped as described herein. The 2N add/drop ports 272
includes 14 local add/drop 260 channels on each of the CWSS 250D,
250M and 12 express connections between the express ports 258B for
the degree-to-degree connectivity 262. In an embodiment, express
connections 280 can be internally connected inside the ROADM degree
and add/drop module 202 (as illustrated in FIG. 5). In another
embodiment, the express ports 258B can also have faceplate ports on
the ROADM degree and add/drop module 202 and the express
connections 280 can be formed by cabling between the faceplate
ports.
[0045] Note, each of the CWSS 250D, 250M is M.times.N, so the
overall ROADM degree and add/drop module 202 can have 2M common
ports and 2N add/drop ports on the faceplate, i.e., each port can
connect to one optical fiber and a channel can be an input and an
output port. Additionally, the term port used herein can refer to
two physical connections on the ROADM degree and add/drop module
202. For example, an input and output port physically has two
connections--one each for input and output. For example, the CWSS
250D, 250M are deployed in a so-called twin module. The express
connections 280 can be ports of each of the twin connected to one
another.
ROADM Node with an Optimized CDC Architecture
[0046] In an embodiment, a ROADM node with an optimized CDC
architecture includes an integrated ROADM degree and add/drop
module 202 having M common input and output ports 270 and N
add/drop input and output ports 272, wherein the integrated ROADM
degree and add/drop module 202 is formed by an M.times.N
demultiplexer Contentionless Wavelength Selective Switch (CWSS)
250D and an M.times.N multiplexer CWSS 250M, M and N are integers;
and X degree modules 204, X is an integer and represents a number
of degrees of the ROADM node, each having an input and output port
connected to associated common ports 270 of the integrated ROADM
degree and add/drop module 202, wherein a first set of ports 258B
of the N add/drop input and output ports 272 are connected between
the demultiplexer CWSS 250D and the multiplexer CWSS 250M for
degree-to-degree connectivity 262 and a second set of ports 258A of
the N add/drop input and output ports 272 are utilized for local
add/drop 260 of channels, such that the integrated ROADM degree and
add/drop module 202 provides both the degree-to-degree connectivity
262 and the local add/drop 260 of channels utilizing the
demultiplexer CWSS 250D and the multiplexer CWSS 250M. Optionally,
the number of degrees is X.ltoreq.4.
[0047] The first set of ports 258B is X*(X-1) input and output
ports and the second set of ports 258A is N-X*(X-1) input and
output ports. M-X input and output ports of the M common input and
output ports 270 are unequipped. The first set of ports 258B
include input and output ports for each degree to connect to every
other degree. The demultiplexer CWSS 250D and the multiplexer CWSS
250M each include M 1.times.N Wavelength Selective Switches (WSSs)
252 each connected to one of M common ports 256; and N M.times.1
selector switches 254 each connected to each of the M 1.times.N
WSSs 252 and connected to N add/drop ports 258. The M 1.times.N
WSSs 252 are each formed using Liquid Crystal On Silicon (LCOS) and
the N M.times.1 selector switches 254 are formed using
Microelectromechanical systems (MEMS) mirrors. The X degree modules
204 each can include a pre-amplifier 206, a post-amplifier 208, and
an Optical Service Channel (OSC) module 210.
[0048] In another embodiment, an integrated ROADM degree and
add/drop module 202 with an optimized CDC architecture includes M
common input and output ports 270; and N add/drop input and output
ports 272, an M.times.N demultiplexer Contentionless Wavelength
Selective Switch (CWSS) 250D and an M.times.N multiplexer CWSS
250M, M and N are integers, configured to optically connect the M
common input and output ports 270 and the N add/drop input and
output ports 272, wherein the integrated ROADM degree and add/drop
module 202 is utilized in an X degree ROADM node, X is an integer,
and wherein a first set of ports 258B of the N add/drop input and
output ports 272 are connected between the demultiplexer CWSS 250D
and the multiplexer CWSS 250M for degree-to-degree connectivity 262
and a second set of ports 258A of the N add/drop input and output
ports 272 are utilized for local add/drop 260 of channels, such
that the integrated ROADM degree and add/drop module 202 provides
both the degree-to-degree connectivity 262 and the local add/drop
260 of channels utilizing the demultiplexer CWSS 250D and the
multiplexer CWSS 250M.
Redundant Configuration
[0049] FIG. 7 is a block diagram of module connectivity in an
optimized ROAM node 200A which includes two ROADM degree and
add/drop modules 202A, 202B for redundancy and/or increased port
count. The optimized ROAM node 200A in FIG. 7 is similar to the
optimized ROAM node 200 in FIG. 5 with four amplifier modules 204A,
204B, 204C, 204D. Again, for illustration purposes, FIG. 7
illustrates a four-degree configuration and other degree
configurations are also contemplated. The optimized ROAM node 200A
includes two of the ROADM degree and add/drop modules 202A, 202B
along with a splitter 300 located between the ROADM degree and
add/drop modules 202A, 202B and the amplifier modules 204A, 204B,
204C, 204D. The splitter 300 is a passive splitter array in both
the transmit and the receive direction.
[0050] Functionally, the optimized ROAM node 200A provides
redundancy, namely the ROADM degree and add/drop modules 202 is not
a single point of failure. However, the optimized ROAM node 200A
can also support 2.times. the port count due to the presence of two
ROADM degree and add/drop modules 202A, 202B. For example, the
optimized ROAM node 200A can support additional local add/drop
ports.
[0051] On the add/drop ports 272, there can be a second transceiver
for 1+1/1:1/etc. protection or an Optical Protection Switch (OPS)
which only utilizes a single transceiver. With the optimized ROAM
node 200A for redundancy, there is protection against a complete
node failure in the event a single ROADM degree and add/drop module
202 fails. Also, the optimized ROAM node 200A can also provide
express redundancy, software could detect a failed ROADM degree and
add/drop module 202A and route the express traffic via the second
ROADM degree and add/drop module 202B.
[0052] It will be appreciated that some embodiments described
herein may include one or more generic or specialized processors
("one or more processors") such as microprocessors; Central
Processing Units (CPUs); Digital Signal Processors (DSPs):
customized processors such as Network Processors (NPs) or Network
Processing Units (NPUs), Graphics Processing Units (GPUs), or the
like; Field Programmable Gate Arrays (FPGAs); and the like along
with unique stored program instructions (including both software
and firmware) for control thereof to implement, in conjunction with
certain non-processor circuits, some, most, or all of the functions
of the methods and/or systems described herein. Alternatively, some
or all functions may be implemented by a state machine that has no
stored program instructions, or in one or more Application Specific
Integrated Circuits (ASICs), in which each function or some
combinations of certain of the functions are implemented as custom
logic or circuitry. Of course, a combination of the aforementioned
approaches may be used. For some of the embodiments described
herein, a corresponding device in hardware and optionally with
software, firmware, and a combination thereof can be referred to as
"circuitry configured or adapted to," "logic configured or adapted
to," etc. perform a set of operations, steps, methods, processes,
algorithms, functions, techniques, etc. on digital and/or analog
signals as described herein for the various embodiments.
[0053] Moreover, some embodiments may include a non-transitory
computer-readable storage medium having computer readable code
stored thereon for programming a computer, server, appliance,
device, processor, circuit, etc. each of which may include a
processor to perform functions as described and claimed herein.
Examples of such computer-readable storage mediums include, but are
not limited to, a hard disk, an optical storage device, a magnetic
storage device, a ROM (Read Only Memory), a PROM (Programmable Read
Only Memory), an EPROM (Erasable Programmable Read Only Memory), an
EEPROM (Electrically Erasable Programmable Read Only Memory), Flash
memory, and the like. When stored in the non-transitory
computer-readable medium, software can include instructions
executable by a processor or device (e.g., any type of programmable
circuitry or logic) that, in response to such execution, cause a
processor or the device to perform a set of operations, steps,
methods, processes, algorithms, functions, techniques, etc. as
described herein for the various embodiments.
[0054] Although the present disclosure has been illustrated and
described herein with reference to preferred embodiments and
specific examples thereof, it will be readily apparent to those of
ordinary skill in the art that other embodiments and examples may
perform similar functions and/or achieve like results. All such
equivalent embodiments and examples are within the spirit and scope
of the present disclosure, are contemplated thereby, and are
intended to be covered by the following claims.
* * * * *