U.S. patent application number 10/179901 was filed with the patent office on 2003-01-09 for integrated multi-rate cross-connect system.
Invention is credited to Deschaine, Stephen A., Doss, Dwight W., Hanson, Gary D., Read, E. Lawrence, Schroder, Richard, Sensel, Steven D., Traupman, Edward P., Weldon, Richard S..
Application Number | 20030007491 10/179901 |
Document ID | / |
Family ID | 22644807 |
Filed Date | 2003-01-09 |
United States Patent
Application |
20030007491 |
Kind Code |
A1 |
Read, E. Lawrence ; et
al. |
January 9, 2003 |
Integrated multi-rate cross-connect system
Abstract
An integrated multi-rate cross-connect system (10) includes a
broadband subsystem (14) for processing optical and electrical
telecommunication network signals. A wideband subsystem (16)
processes wideband level electrical telecommunication signals from
the network, from the broadband subsystem (14), and from a
narrowband subsystem (18). The narrowband subsystem (18) processes
narrowband level electrical telecommunication signals from the
network and the wideband subsystem (16). An administration
subsystem (12) provides centralized control and synchronization to
the broadband subsystem (14), the wideband subsystem (16), and the
narrowband subsystem (18). The wideband subsystem (16) is coupled
to the broadband subsystem (14) and the narrowband subsystem (18)
by internal transmission links (30) to allow for remote
distribution of each subsystem. Each subsystem operates within its
own timing island synchronized to a reference timing signal to
facilitate component distribution.
Inventors: |
Read, E. Lawrence; (Plano,
TX) ; Deschaine, Stephen A.; (Garland, TX) ;
Doss, Dwight W.; (Richardson, TX) ; Hanson, Gary
D.; (Plano, TX) ; Sensel, Steven D.; (The
Colony, TX) ; Schroder, Richard; (Plano, TX) ;
Traupman, Edward P.; (Fairview, TX) ; Weldon, Richard
S.; (Plano, TX) |
Correspondence
Address: |
ALCATEL USA
INTELLECTUAL PROPERTY DEPARTMENT
1000 COIT ROAD, MS LEGL2
PLANO
TX
75075
US
|
Family ID: |
22644807 |
Appl. No.: |
10/179901 |
Filed: |
June 25, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10179901 |
Jun 25, 2002 |
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09083798 |
May 22, 1998 |
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09083798 |
May 22, 1998 |
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08762931 |
Dec 10, 1996 |
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5757793 |
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08762931 |
Dec 10, 1996 |
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08176548 |
Dec 30, 1993 |
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5436890 |
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Current U.S.
Class: |
370/395.1 ;
370/401 |
Current CPC
Class: |
H04J 2203/0041 20130101;
H04J 2203/0089 20130101; H04Q 2213/13208 20130101; H04J 3/1611
20130101; H04J 2203/0012 20130101; H04J 2203/006 20130101; H04Q
2213/13216 20130101; H04Q 11/0478 20130101; H04Q 11/04 20130101;
H04Q 2213/1336 20130101; H04Q 2213/13292 20130101; H04Q 2213/13367
20130101; H04J 2203/0003 20130101; H04Q 2213/1301 20130101; H04Q
2213/1304 20130101; H04Q 2213/13332 20130101; H04Q 2213/1302
20130101; H04J 3/0685 20130101 |
Class at
Publication: |
370/395.1 ;
370/401 |
International
Class: |
H04L 012/56 |
Claims
What is claimed is:
1. An integrated multi-rate cross-connect system in a
telecommunication network, comprising: a broadband subsystem for
processing and cross-connecting broadband frequency level optical
and electrical telecommunication network signals; a wideband
subsystem for processing and cross-connecting wideband frequency
level electrical telecommunication signals from a network interface
and directly from said broadband subsystem without passing through
a network interface; a narrowband subsystem for processing and
cross-connecting narrowband frequency level electrical
telecommunication signals from a network interface and directly
from said wideband subsystem without using a network interface,
said wideband subsystem operable to process electrical
telecommunication signals from said narrowband subsystem; an
administration subsystem for providing centralized control and
synchronization to said broadband, wideband, and narrowband
subsystems.
2. The integrated multi-rate cross-connect system of claim 1,
further comprising: internal transmission links coupling said
broadband subsystem with said wideband subsystem and said wideband
subsystem with said narrowband subsystem to allow for remote
geographic distribution of said broadband, wideband, and narrowband
subsystems.
3. The integrated multi-rate cross connect system of claim 2,
wherein said internal transmission links carry optical signals in
an internal format common to each subsystem.
4. The integrated multi-rate cross-connect system of claim 1,
wherein said broadband, wideband, and narrowband subsystems are
organized into separate timing islands synchronized by said
administration subsystem to facilitate remote distribution and
integration of said broadband, wideband, and narrowband
subsystems.
5. The integrated multi-rate cross-connect system of claim 4,
wherein said wideband subsystem includes tributary signal
processing units to interface said wideband subsystem to said
broadband and narrowband subsystems for transmission of signals and
conversion between said timing islands.
6. The integrated multi-rate cross-connect system of claim 5,
wherein said tributary signal processing units process higher rate
signals to lower rate signals and lower rate signals to higher rate
signals and provide gateway functions and mapping between
asynchronous and synchronous signal types.
7. The integrated multi-rate cross-connect system of claim 1,
wherein said administration subsystem includes: an administration
unit for generating control information to each subsystem; and a
timing/communication controller unit for distributing timing
information to each subsystem.
8. The integrated multi-rate cross-connect system of claim 7,
wherein said timing/communication controller unit includes unit
managers for receiving control information from said administration
unit and distributing said control information to components in
each subsystem.
9. The integrated multi-rate cross-connect system of claim 8,
wherein said broadband, wideband, and narrowband subsystems include
a plurality of unit controllers for receiving and processing said
control information distributed by said unit managers.
10. The integrated multi-rate cross-connect system of claim 7,
wherein said timing/communication controller unit synchronizes said
subsystems from an office timing source or in response to signals
received from the network.
11. The integrated multi-rate cross-connect system of claim 7,
wherein said administration unit includes a processor for
interfacing with a central office and an operator in order to
generate said control information.
12. The integrated multi-rate cross-connect system of claim 1,
wherein said broadband subsystem includes: a high speed optical
unit for processing synchronous optical signals; a high speed
electrical unit for processing synchronous and asynchronous
electrical signals; and a broadband matrix unit for
cross-connecting said optical and electrical signals, said
broadband matrix unit coupled to said high speed optical unit and
said high speed electrical unit by internal transmission links
carrying optical signals in an internal format.
13. The integrated multi-rate cross-connect system of claim 1,
wherein said narrowband subsystem includes: a subrate interface
unit for processing network signals; a narrowband interface unit
for processing internal signals from and to said wideband
subsystem; and a narrowband matrix unit for cross-connecting said
network and internal signals, said narrowband interface unit
coupled to said wideband subsystem by an internal transmission link
carrying optical signals in an internal format.
14. The integrated multi-rate cross-connect system of claim 1,
wherein said wideband subsystem includes: a low speed electrical
unit for processing network signals; a plurality of tributary
signal processing units for processing signal information at said
broadband subsystem, said narrowband subsystem, and said low speed
electrical unit; and a wideband matrix center stage for
cross-connecting said signal information, said tributary signal
processing unit communicating with said broadband subsystem, said
narrowband subsystem, and said low speed electrical unit over
internal transmission links carrying optical signals in a first
internal format, said tributary signal processing system
communicating with said wideband matrix center stage through a
second internal format.
15. An integrated multi-rate cross-connect system in a
telecommunication network, comprising: a broadband subsystem for
terminating broadband frequency level optical and electrical
telecommunication network signals, said broadband subsystem
includes a high speed optical unit for processing synchronous
optical signals, a high speed electrical unit for processing
synchronous and asynchronous electrical signals, and a broadband
matrix unit for cross-connecting said optical and electrical
signals, said broadband matrix unit coupled to said high speed
optical unit and said high speed electrical unit by internal
transmission links carrying optical signals in a first internal
format; a wideband subsystem for processing wideband frequency
level electrical telecommunication signals from the network and
said broadband subsystem, said wideband subsystem includes a low
speed electrical unit for processing network signals, a plurality
of tributary signal processing units for processing signal
information from said broadband subsystem, said narrowband
subsystem, and said low speed electrical unit, and a wideband
matrix center stage for cross-connecting said signal information,
said tributary signal processing unit communicating with said
broadband subsystem, said narrowband subsystem, and said low speed
electrical unit over internal transmission links carrying optical
signals in said first internal format, said tributary signal
processing system communicating with said wideband matrix center
stage through a second internal format; a narrowband subsystem for
processing narrowband frequency level electrical telecommunication
signals from the network and said wideband subsystem, said wideband
subsystem operable to process electrical telecommunication signals
from said narrowband subsystem, said narrowband subsystem includes
a cross-connect interface unit for processing network signals, a
narrowband interface unit for processing internal signals from and
to said wideband subsystem, and a narrowband matrix unit for
cross-connecting said network and internal signals, said narrowband
interface unit coupled to said wideband subsystem by an internal
transmission link carrying optical signal in said first internal
format; an administration subsystem for providing centralized
control and synchronization to said broadband, wideband, and
narrowband subsystems, said administration subsystem includes an
administration unit for generating control information to each
subsystem and a timing/communication controller for distributing
timing information and to each subsystem.
16. The integrated multi-rate cross-connect system of claim 15,
wherein said administration subsystem provides test capabilities
for all signals cross-connected in each subsystem for direct access
to narrowband, wideband, and broadband signals.
17. The integrated multi-rate cross-connect system of claim 15,
further comprising an asynchronous transfer mode subsystem for
transmitting network signals in asynchronous transfer mode
cells.
18. The integrated multi-rate cross-connect system of claim 15,
further comprising redundant signal paths and protection schemes
throughout each subsystem to increase reliability and improve
operation.
19. The integrated multi-rate cross-connect system of claim 15,
wherein each subsystem operates on a specific time base within a
separate timing island to facilitate remote distribution and
integration of each subsystem.
Description
TECHNICAL FIELD OF THE INVENTION
[0001] The present invention relates in general to
telecommunications switching systems and more particularly to an
integrated multi-rate cross-connect system.
BACKGROUND OF THE INVENTION
[0002] Digital cross-connect systems are an integral part of
today's modern telecommunications transport network. They are
increasingly used by all service providers including exchange
carriers, long distance carriers, and competitive by-pass carriers.
Significant technology advancements have allowed digital
cross-connect systems to evolve from narrowband grooming and test
applications to cross-connection of larger network signals in
wideband and broadband frequency domains.
[0003] Conventional digital cross-connect systems have largely been
based on a single core architecture approach where all
cross-connections are made through a single switching node or
matrix. However, most transport network architectures are based on
a layered signal structure where one layer must be completely
exposed or processed before accessing the next layer. To completely
handle layered signal structure network architectures, digital
cross-connect systems capable of handling different feature
requirements must be connected in series.
[0004] For multiple digital cross-connect systems connected in
series, a broadband system is first used to terminate high speed
optical and electrical signals in order to path terminate and groom
lower speed broadband signals. The broadband system also supports
performance monitoring and test access functions. A payload
containing the broadband signals is then connected to a wideband
system to support similar functions in obtaining wideband signals.
The wideband signals are then terminated by a narrowband system.
For a hub office, the procedure is done in reverse order in order
for signals to leave the office.
[0005] As new services, new capabilities, and new network transport
signals that increase network complexity develop and evolve, a
higher emphasis is placed on test access functions to improve
network survivability and service quality through quick fault
isolation and reduce outage duration. However, in conventional
cross-connect systems connected in series, once a signal is
terminated to extract embedded signals, access monitoring and test
of the terminated signal is lost.
[0006] A series of single digital cross-connect systems cannot
provide complete test access to signals carried over the network.
Failure to provide complete performance monitoring, test access,
path termination, and grooming functions at all network levels can
significantly impact network survivability and office
flexibility.
[0007] From the foregoing, we have recognized that a need has
arisen for a digital cross-connect system that overcomes the
reliability problems of conventional digital cross-connect systems.
We have conceived that there is a utility for a digital
cross-connect system that can perform complete test access and
monitoring of all signals in a layered signal structure. Further,
it would be advantageous to have a single cross-connect system that
can process all signals embedded within a multi-layer signal
structure.
SUMMARY OF THE INVENTION
[0008] In accordance with the present invention, an integrated
multi-rate cross-connect system is provided which substantially
eliminates or reduces disadvantages and problems associated with
conventional series linked digital cross-connect systems.
[0009] According to an embodiment of the present invention, there
is provided an integrated multi-rate cross-connect system that
includes a broadband subsystem for processing and cross-connecting
broadband frequency level optical and electrical communication
network signals. A wideband subsystem processes and cross-connects
wideband frequency level electrical telecommunication signals from
the network and the broadband subsystem. A narrowband subsystem
processes and cross-connects narrowband frequency level electrical
telecommunication signals from the network and the wideband
subsystem.
[0010] The broadband subsystem also processes and cross-connects
signals from the wideband system. The wideband subsystem also
processes and cross-connects electrical telecommunication signals
from the narrowband subsystem. Each of the broadband, wideband, and
narrowband subsystems are under the centralized control of an
administration subsystem that provides synchronization, monitoring,
and control for the integrated multi-rate cross-connect system.
[0011] The integrated multi-rate cross-connect system of the
present invention provides various technical advantages over
conventional single subsystem digital cross-connect systems. For
example, one technical advantage is in implementing narrowband,
wideband, and broadband subsystems within an integrated system.
Another technical advantage is in providing centralized control and
synchronization to each separate subsystem of the integrated
multi-rate cross-connect system.
[0012] Yet another technical advantage is to provide test access
and fault coverage to all layered signals of a signal structure.
Still another technical advantage is the reduction in the number of
network interfaces and the increased speed and reliability as
compared to stand alone cross-connect systems. Other technical
advantages are readily apparent to one skilled in the art from the
following figures, descriptions, and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] For a more complete understanding of the present invention
and the advantages thereof, reference is now made to the following
description taken in conjunction with the accompanying drawings,
wherein like reference numerals represent like parts, in which:
[0014] FIG. 1 illustrates a conceptual block diagram of an
integrated multi-rate cross-connect system;
[0015] FIG. 2 illustrates a block diagram of an architecture for
the integrated multi-rate cross-connect system;
[0016] FIG. 3 illustrates a block diagram of a control architecture
for the integrated multi-rate cross-connect system;
[0017] FIG. 4 illustrates a block diagram of a timing distribution
for the integrated multi-rate cross-connect system;
[0018] FIG. 5 illustrates a timing island concept for the
integrated multi-rate cross-connect system;
[0019] FIG. 6 illustrates a block diagram of a portion of a
broadband subsystem within the integrated multi-rate cross-connect
system;
[0020] FIG. 7 illustrates an example of an overhead format for
signals used within the broadband subsystem;
[0021] FIG. 8 illustrates a block diagram of a portion of the
broadband system;
[0022] FIG. 9 illustrates a block diagram of a cross-connect matrix
within the broadband subsystem;
[0023] FIG. 10 illustrates a block diagram of a wideband subsystem
within the integrated multi-rate cross-connect system;
[0024] FIG. 11 illustrates a block diagram of a narrowband
subsystem within the integrated multi-rate cross-connect
system;
[0025] FIG. 12 illustrates examples of matrix payload capacity
frames generated by the integrated multi-rate cross-connect
system;
[0026] FIG. 13 illustrates examples of matrix payload envelopes
generated by the integrated multi-rate cross-connect system;
and
[0027] FIG. 14 illustrates a matrix transport format for the
integrated multi-rate cross-connect system.
DETAILED DESCRIPTION OF THE INVENTION
I. Conceptual Organization
[0028] FIG. 1 is a conceptual block diagram of an integrated
multi-rate cross-connect system 10. Integrated multi-rate
cross-connect system 10 includes a broadband subsystem 14, a
wideband subsystem 16, and a narrowband subsystem 18 under the
control of an administration subsystem 12. Integrated multi-rate
cross-connect system 10 integrates different subsystem types into a
single cross-connect system. Broadband subsystem 14 receives
network optical and electrical signals through a broadband
interface unit 13 for processing and cross-connection back to the
network or to wideband subsystem 16. Wideband subsystem 16 receives
lower rate network signals through a wideband interface unit 15 for
cross-connection back to the network directly or through broadband
subsystem 14 or narrowband subsystem 18.
[0029] Wideband subsystem 16 also receives higher rate signals from
broadband subsystem 14 for path termination, demultiplexing,
processing, and cross-connection through a tributary signal
processing resource. The resource concept employed in wideband
subsystem 16 is a significant advantage of integrated multi-rate
cross-connect system 10, providing a pool of easily managed
resources, such as multiplexers, which can be provisioned and
reassigned on demand rather than as dedicated hardware which
requires physical installation and removal to implement
configuration changes.
[0030] Narrowband subsystem 18 receives network signals through a
narrowband interface unit 17 for cross-connection back to the
network or to wideband subsystem 16. Similar tributary signal
processing resources are used to connect wideband signals to
narrowband subsystem 18 for path termination, processing, and
cross-connection.
[0031] Administration subsystem 12 provides centralized control,
monitoring, and synchronization to each subsystem within integrated
multi-rate cross-connect system 10. Synchronization is performed
through a central office standard reference frequency or derived
from network signal timing. Integrated multi-rate cross-connect
system 10 also includes an asynchronous transfer mode subsystem 19
to allow integrated multi-rate cross-connect system 10 to
communicate over the network through ATM cell packet
transmission.
II. System Architecture
[0032] FIG. 2 is a high level system architecture of integrated
multi-rate cross-connect system 10. Integrated multi-rate
cross-connect system 10 provides an integrated platform for
cross-connecting signals at broadband, wideband, and narrowband
levels and supports cross-connection of both domestic and
international rates and formats. For purposes of this description,
discussion is limited to domestic signalling at DS-1, DS-3, STS-1,
OC-3, and OC-12 rates though integrated multi-rate cross-connect
system 10 may also process signals at other rates.
[0033] Integrated multi-rate cross-connect system 10 terminates
synchronous optical (OC-3, OC-12), synchronous electrical (STS-1),
and asynchronous electrical (DS-3, DS-1) network signals.
Cross-connection is provided via a multi-rate, multi-subsystem
architecture that ensures maximum flexibility and growth at all
network levels. With multiple subsystems under a single
administrative control, integrated multi-rate cross-connect system
10 manages individual high capacity, non-blocking matrix subsystems
in order to perform cross-connections. Integrated multi-rate
cross-connect system 10 includes an administration subsystem 12, a
broadband subsystem 14, a wideband subsystem 16, and a narrowband
subsystem 18.
[0034] Administration subsystem 12 includes an administration unit
20 and a timing/communication controller (TCC) unit 22.
Administration unit 20 performs operations, administration,
maintenance, and provisioning (OAM&P) functions for integrated
multi-rate cross-connect system 10. Administration unit 20 provides
communication interfaces to a user. Administration unit 20 also
interfaces with central office discrete signals and provides alarm
conditions to the central office alarm systems. Local or remote
terminal access is provided through a craft interface.
Administration unit 20 handles system control for integrated
multi-rate cross-connect system 10 through a hierarchical
distribution scheme among the various components of the system.
[0035] Timing/communication controller unit 22 provides
communications and timing functions for integrated multi-rate
cross-connect system 10. Timing/communications controller unit 22
receives an office timing source to generate the internal timing
for synchronizing broadband subsystem 14, wideband subsystem 16,
and narrowband subsystem 18 and controls every component within
integrated multi-rate cross-connect system 10 through a hierarchy
of controllers as supervised by administration unit 20. Timing
synchronization may also be derived from network signals for
distribution to each subsystem. Synchronization and control
information are distributed throughout integrated multi-rate
cross-connect system 10 by timing/communication controller unit 22.
Communication to terminals outside integrated multi-rate
cross-connect system 10 is provided through a remote communication
interface. Timing/communication controller unit 22 provides a
communication interface to an operations support system.
[0036] Broadband subsystem 14 includes three unit types--high speed
optical (HSO) units 24, high speed electrical (HSE) units 26, and a
broadband matrix unit 28. Broadband subsystem 14 supports network
termination of DS-3, STS-1, OC-3, and OC-12 signals as well as
international termination capability. High speed optical unit 24
terminates synchronous optical signals at the OC-3 and OC-12 rates.
High speed electrical unit 26 provides electrical termination of
asynchronous electrical and synchronous electrical signals at the
DS-3 and STS-1 rates, respectively. Broadband subsystem 14 also
processes section and line overhead fields. Network signals are
cross-connected through broadband subsystem 14 through internal
STS-1 signals having an STS-1 rate locked to the time base of
broadband subsystem 14, but with an alternate use of overhead from
standard STS-1 signal processing. Signals are transported through
broadband subsystem 14 in STS-1 frames at transport rate of 51.84
Mb/s.
[0037] High speed optical unit 24 and high speed electrical unit 26
act as interfaces between broadband matrix unit 28 and the network
optical and electrical domains, respectively. High speed optical
unit 24 and high speed electrical unit 26 monitor the quality of
the data streams and provide a protection scheme by switching from
a failed channel to a dedicated protection channel upon detection
of a degraded signal. High speed optical unit 24 and high speed
electrical unit 26 also insert and extract overhead data which is
used to carry information about the payload and perform
communication with other network elements.
[0038] High speed optical unit 24 and high speed electrical unit 26
connect to broadband matrix unit 28 through internal transmission
links 30. Internal transmission link 30 may be up to 2 kilometers
in length to allow high speed optical units 24 and high speed
electrical units 26 to be remotely located from broadband matrix
unit 28. Internal transmission link 30 carries optical signals and
permits flexibility in physical arrangement and location of
integrated multi-rate cross-connect system 10 components. Broadband
matrix unit 28 provides redundant three stage non-blocking
cross-connects at the STS-1 rate with error free redundant plane
and clock switching arrangement under normal operating
conditions.
[0039] Wideband subsystem 16 includes three unit types--low speed
electrical units 32, tributary signal processing units 38, and
wideband matrix center stage 40. Wideband subsystem 16 supports
network termination of DS-3 and DS-1 signals as well as
international termination capability. Network signals are
cross-connected through wideband subsystem 16 in an internal matrix
transport format.
[0040] Low speed electrical units 32 provide network termination of
asynchronous electrical signals at the DS-1 rate. Termination of
DS-3 signals is performed by interfacing with existing switching
equipment (not shown).
[0041] Tributary signal processing units 38 act as interfaces
between wideband matrix center stage 40 and broadband matrix unit
28, low speed electrical units 32, and narrowband subsystem 18
through communication over respective internal transmission links
30. Tributary signal processing units 38 perform multiplexing
format conversion and mapping functions between synchronous optical
network (SONET) and asynchronous signals. Tributary signal
processing units 38 are also used as the interface to narrowband
subsystem 18 for access to DS-0 rate services. Originating and
terminating stages of the wideband matrix are provided by tributary
signal processing units 38 for interfacing with wideband matrix
center stage 40 in order to provide redundant three stage
non-blocking cross-connects with error free redundant plane and
clock switching arrangement under normal operating conditions.
[0042] Wideband subsystem 16 signals are cross-connected at
VT1.5-VT6 rates into internal synchronous channels 42 having a
wideband matrix transport format (MTF) of a matrix payload envelope
capable of carrying the VT rated signal. Higher rate network
signals including DS-3 and STS-1 discussed in conjunction with
broadband subsystem 14 will normally access wideband subsystem 16
for tributary access or switching through broadband subsystem 14
over internal transmission links 30 and tributary signal processing
unit 38.
[0043] Narrowband subsystem 18 includes three unit
types--narrowband interface unit 44, subrate interface units 46,
and a narrowband matrix unit 48. Narrowband subsystem 18 signals
are cross-connected preferably at a DS-0 rate. An optional subrate
interface unit 46 provides direct electrical termination of signals
at the DS-1 and DS-3 rates. However, instead of direct signal
termination, narrowband subsystem 18 normally accesses network
traffic through wideband subsystem 16.
[0044] For access to lower level signal rate components, wideband
subsystem 16 routes its VT rated cross-connect signals to
narrowband subsystem 18 for processing into DS-0 signals.
Narrowband interface unit 44 provides the interface to wideband
subsystem 16 through an internal transmission link 30. Narrowband
matrix unit 48 provides redundant non-blocking dual time slot
interchange matrix planes to cross-connect signals at lower rate
levels, including the DS-0 rate and subrate levels.
[0045] As shown throughout, integrated multi-rate cross-connect
system 10 also uses redundant data paths in coupling each component
together to increase operation reliability. Each subsystem is
organized in dual independent planes with no cross coupling within
the planes. Each unit within each subsystem has access to both
planes and is capable of independently selecting an active plane.
Thus, a number of failures can be accommodated in both planes
without loss of network traffic.
III. Control Structure
[0046] Integrated multi-rate cross-connect system 10 has a control
structure that operates through a three tier processing hierarchy.
FIG. 3 is a high level view of the control structure for integrated
multi-rate cross-connect system 10. Top level control is found
within administration unit 20 of administration subsystem 12.
Though integrated multi-rate cross-connect system 10 implements
multiple subsystems at multiple rates, for administrative purposes
cross-connections are created across a single logical
subsystem.
[0047] Administration unit 20 includes redundant processors 50 to
provide the platform to perform operations, administration,
maintenance, and provisioning (OAM&P) functions. Processors 50
perform the monitoring and control for integrated multi-rate
cross-connect system 10. Processors 50 interface with central
office discrete signals through serial interface 52 to perform top
level monitoring and control for integrated multi-rate
cross-connect system 10. Maintenance access to processors 50 is
accomplished through either a local terminal 54 or by remote access
through a modem 56. An RS232 switch 58 determines whether access to
processors 50 is by local or remote terminals.
[0048] Administration unit 20 also includes an alarm interface 60
that provides interfaces to central office discrete signals. Alarm
interface 60 performs intelligent watchdog communications to each
processor 50, monitors and processes alarm conditions, and controls
reset of processors 50. Alarm interface 60 also provides input
sense points and contact closures for system and customer use.
Remote alarm surveillance and processing may be accomplished over
an E2A serial communications channel.
[0049] Operator system control is available through a graphical
user interface over terminals 62. The graphical user interface
provides an intuitive interface between the operator and the
functions of integrated multi-rate cross-connect system 10. The
operator uses a point and click system in a control and analysis
environment that simplifies system operation and dramatically
shortens training time.
[0050] The second tier in the control hierarchy are unit managers
64 found within timing/communications control unit 22. Unit manager
64 provides a redundant communications and control path between
processor 50 and the third level of the control hierarchy.
Intrasystem control information is sent from administration unit 20
to unit manager 64. Unit manager 64 provides intermediate level
OAM&P functions. Communications between processors 50 and
between unit manager 64 and processors 50 may be accomplished by a
redundant ethernet local area network. Serial interface 52 provides
communications between a central office or other external source
and processors 50 and unit manager 64.
[0051] Timing/communications control unit 22 also includes a
synchronizer 66 that accepts a central office timing source and
generates the timing signals required for broadband subsystem 14,
wideband subsystem 16, and narrowband subsystem 18. Separate
synchronizer units may be provided for each subsystem. If
additional timing signals are required for the subsystems, a
synchronizer distributor 68 works in conjunction with synchronizer
66 to provide the additional signals. Unit manager 64 provides
control information to synchronizer 66 and synchronizer
distributor. 68.
[0052] The third tier of the control hierarchy is performed by unit
controllers 70 located in each component and unit of broadband
subsystem 14, wideband subsystem 16, and narrowband subsystem 18.
Unit controller 70 controls and monitors functions provided in
associated matrix units and performs the low level OAM&P
function. Control information transmitted between unit manager 64
and unit controller 70 may be carried on internal transmission
links 30 or through direct cabling connections as determined by
location constraints. Redundant unit controllers 70 are found in
all components of each subsystem including high speed optical unit
24, high speed electrical unit 26, broadband matrix unit 28, low
speed electrical unit 32, tributary signal processing unit 38, and
wideband center stage matrix 40, as shown.
IV. Timing Considerations
[0053] As previously discussed, timing/communications controller
unit 22 provides the timing signals for broadband subsystem 14,
wideband subsystem 16, and narrowband subsystem 18 through
synchronizer 66 and, if necessary, synchronizer distributor 68.
Synchronizer 66 processes a central office timing source and
generates timing signals required for each subsystem. Synchronizer
distributor 68 provides fanout of timing signals from synchronizer
66 for additional timing signal requirements. Unit managers 64
provide a redundant control path between administration unit 20 and
synchronizers 66.
[0054] FIG. 4 is a block diagram of the timing distribution for
integrated multi-rate cross-connect system 10. A stratum-3 timebase
is incorporated for each cross-connect subsystem in separate timing
units 72. Maintenance and control functions associated with each
timing unit 72 is performed through a unit manager 64 of
timing/communication controller 22. Subsystem timing units 72 are
synchronized to an office timing source, or timing reference
signals may be derived by signals received from the network.
Subsystem timing units 72 will generate timing distribution signals
74 based on a selected office reference signal for distribution to
the appropriate matrix. Timing signals are hierarchically
distributed to other units throughout the associated subsystem by a
respective timing unit 72.
[0055] Integrated multi-rate cross-connect system 10 is capable of
providing signals that may be used as timing references to the
office time base or may be connected directly to subsystem timing
units 72. Low speed electrical unit 32 of wideband subsystem 16 or
high speed optical unit 24 of broadband subsystem 14 may provide
lower rate timing reference signals for the office time base or
subsystem timing units 72.
[0056] FIG. 5 shows a timing configuration for integrated
multi-rate cross-connect system 10. Each subsystem is separated
into its own unique timing island operating off of a specific time
base. Synchronization is performed between timing islands in order
to convert from one time base to another. Broadband subsystem 16
operates within a broadband time base 76, wideband subsystem 16
operates within a wideband time base 77, and narrowband subsystem
18 operates within a narrowband time base 78. Tributary signal
processing unit 38 that couples wideband subsystem 16 with
broadband subsystem 18 provides the conversion from/to broadband
time base 76 to/from wideband time base 77. Similarly, narrowband
interface 44 that couples narrowband subsystem 18 with wideband
subsystem 16 provides the conversion from/to narrowband time base
78 to/from wideband time base 77.
[0057] The selection of the position of conversion between timing
islands of integrated multi-rate cross-connect system 10 is made to
minimize circuit complexity and SONET pointer movements. For
example, the interface between the broadband and wideband timing
islands for DS-3 mapped STS-1 synchronous payload envelopes will be
at the point where the STS-1 signal path is terminated within
tributary signal processing subsystem 38.
[0058] The timing island concept implemented within integrated
multi-rate cross-connect system 10 allows components and subsystems
to be geographically remotely distributed while maintaining the
integrated characteristics of the system. Further information
regarding timing considerations for integrated multi-rate
cross-connect system 10 can be found in copending U.S. patent
application Ser. No. ______, entitled "Integrated Multi-Fabric
Digital Cross-Connect Timing Architecture", which is hereby
incorporated by reference herein.
V. Broadband Subsystem
[0059] FIG. 6 is block diagrams of a portion broadband subsystem
14. Broadband subsystem 14 includes high speed optical unit 24 and
high speed electrical unit 26 of FIG. 6, and broadband matrix unit
28 as previously described.
[0060] Each high speed optical unit 24 can terminate OC-3 or OC-12
optical signals or terminate a mixture of OC-3 and OC-12 optical
signals. High speed optical unit 24 provides an interface between
the optical network signals and broadband matrix unit 28. High
speed optical unit 24 also monitors the quality of the data and
inserts and extracts overhead data and provides protection
switching when necessary. Internal STS-1P signals are generated and
converted in high speed optical unit 24 and transmitted to and
received from broadband matrix unit 28 over internal transmission
link 30.
[0061] Each high speed optical unit 24 includes an optical
terminator 80 for terminating an appropriate optical signal.
Optical terminator 80 converts the optical signal into an
electrical signal and the data is unscrambled and demultiplexed
into internal STS-1P signals. Redundant internal STS-1P signals are
applied to a pair of groomers 82.
[0062] Groomer 82 is capable of grooming signals such that an
assignment of matrix bandwidth is not required for unused network
capacity and maximum fill of internal transmission links 30 is
achieved to preserve matrix capacity for under filled OC-N signals.
Groomer 82 also provides automatic protection switching in the
event that a degraded signal is detected during a quality check. If
a degraded signal is detected, groomer 82 switches signal transfer
from a failed channel to a dedicated protection channel.
[0063] After processing by groomer 82, internal STS-1P signals are
interfaced to internal transmission link 30 through a matrix
interface 84. Matrix interface 84 transports internal STS-1P
signals from groomer 82 and control signals from unit controller 70
associated with high speed optical unit 24 to broadband matrix unit
28 over internal transmission link 30.
[0064] An attached processor 85 provides multiplexing and
demultiplexing of selected overhead bits for internal STS-1P
mapping through matrix interface 84. Attached processor 85 can also
be used for processing select overhead, specifically new or
modified overhead processing requirements may be accommodated at
attached processor 85.
[0065] High speed electrical unit 26 provides termination of higher
rate electrical signals such as DS-3 and STS-1 and transports them
over internal transmission link 30 to broadband matrix unit 28.
Signals enter and leave high speed electrical unit 26 at a
terminator 86 prior to and after processing by a network processor
88. Redundancy protection is provided by a redundancy switch 90 and
a redundant network processor 92.
[0066] Network processor 88 performs mapping and desynchronizing
required for DS-3 signal to STS-1 synchronous payload envelope
gateway functionality. Network processors 88 and 92 terminate the
respective line rates and perform enhanced performance monitoring
in order to detect a degraded signal and take appropriate action.
Network processors 88 and 92 generate and convert internal STS-1P
signals for placement on and receipt from internal transmission
link 30 by a matrix interface 94.
[0067] Internal transmission link 30 carries system data, overhead,
timing, control, and status information from high speed electrical
unit 26 to broadband matrix unit 28. Matrix interface 94 extracts
control information from internal transmission link 30 for
processing by a unit controller 70 and provides the interface to
broadband matrix unit 28. An attached processor 95 under control of
unit controller 70 processes overhead data for internal STS-1
mapping through matrix interface 94.
[0068] Internal transmission links 30 connect major elements within
integrated multi-rate cross-connect system 10. Internal
transmission links 30 use the rate and frame structure of SONET
OC-12 signals, allowing each internal transmission link 30 to carry
twelve internal STS-1P signals. Internal STS-1 signals carried on
internal transmission links 30 follow the frame format defined for
SONET STS-1 signals.
[0069] Internal STS-1 signals contain 27 bytes per frame of
overhead capacity corresponding to the Section and Line overhead
positions of standard STS-1 signals. The total internal
transmission link 30 overhead capacity for twelve internal STS-1P
signals is 324 bytes per 125 microsecond frame. The internal
transmission link 30 overhead capacity is divided into the
following four fields--STS-1P Overhead (96 bytes), Network Overhead
Transport OHT (192 bytes), ITL Fault Coverage B1 (1 byte), and ITL
Communication Channel ITL-COM (24 bytes).
[0070] FIG. 7 shows the internal use of overhead for internal
STS-1P signals. Matrix interface 84 normally processes overhead
information that is currently well defined. Other overhead
associated with network signals that is not processed at matrix
interface 84 is connected to attached processor 85 for additional
processing capability. Certain overhead fields connected to
attached processor 85 are mapped into OHT fields of the internal
STS-1P signal overhead for transport. OHT fields are generated and
terminated at attached processor 85.
[0071] The STS-1P Overhead fields are generated and terminated at
the point where the internal STS-1P signal frames are created and
terminated in order to provide end to end framing and fault
coverage for the internal STS-1P frames. The B1 signal provides
fault coverage for internal transmission link 30 signals and are
terminated at broadband matrix unit 28. Control information is
transported across internal transmission link 30 through the
ITL-COM channels to allow for communication between unit
controllers 70 and unit manager 64. The OHT fields are used for
mapping of overhead information for each signal (OC-3, OC-12, DS-3,
STS-1) terminated within broadband subsystem 14.
[0072] The four fields defined for the internal STS-1 signal
overhead are multiplexed into the overhead capacity of internal
transmission link 30 at broadband matrix unit 28. Connections for
internal transmission link 30 terminations within wideband system
16 and narrowband system 18 are similar to that shown with respect
to high speed optical unit 24 and high speed electrical unit 26.
However, the ITL-COM field is not used at the wideband/broadband
interface or the wideband/narrowband interface. Further, the OHT
field is not used at the wideband/network, wideband/broadband, and
wideband/narrowband interfaces.
[0073] The STS-1P Overhead field includes bytes A1, A2, H1, H2, and
H3 defined by the SONET standard and bytes EC-BIP, CNTL, and BCID
for internal use. The EC-BIP (Envelope Capacity) field is
associated with SONET defined B2 position so that standard B2
processing can be used. The BCID (Broadband Channel ID) field is
used to carry a unique code assigned to each internal STS-1P signal
associated with broadband subsystem 14. The CNTL field is
associated with alarm handling and fault isolation mechanisms.
[0074] In FIG. 8, broadband matrix unit 28 processes internal
STS-1P signals received and transmitted over internal transmission
link 30 through internal transmission link multiplexers 96 for
cross-connection. Internal transmission link multiplexers 96
interface internal STS-1P signals with cross-connect matrix 98 of
broadband matrix unit 28. Cross-connect matrix 98 performs the
three stage non-blocking switching function for broadband matrix
unit 28. Broadband matrix unit 28 of broadband subsystem 14
interfaces with wideband subsystem 16 at tributary signal
processing unit 38. Unit controller 70 interfaces control
information in overhead space for transmission over internal
transmission link 30.
[0075] Internal STS-1P signals are transported between broadband
matrix unit 28 and tributary signal processing unit 38 over
internal transmission link 30. Internal STS-1P signals between
broadband matrix unit 28 and tributary signal processing unit 38
occur over internal transmission link 30 through internal
transmission link multiplexers 96 of broadband matrix unit 28 and
matrix interfaces 100 of tributary signal processing unit 38.
Information between broadband subsystem 14 and wideband subsystem
16 is processed by tributary signal processor 102 within a
tributary signal processing unit 38. Unit controller 70 interfaces
control information with matrix interface 100 and tributary signal
processor 102.
[0076] FIG. 9 is a block diagram of cross-connect matrix 98 within
broadband matrix unit 28. Cross-connect matrix 28 uses a three
stage architecture capable of switching internal STS-1P signals at
the STS-1 rate. The three matrix stages for cross-connect matrix 98
are designated as the originating stage, center stage, and
terminating stage. Internal transmission link multiplexers 96 are
associated with the originating stage and the terminating stage of
cross-connect matrix 98. Internal transmission link multiplexers 96
demultiplex inbound internal STS-1P signals at the OC-12 rate for
cross-connection at the STS-1 rate. Internal transmission link
multiplexers 96 also multiplex outbound internal STS-1P signals for
transmission on internal transmission links 30.
VI. Wideband Subsystem
[0077] Internal STS-1P signals may be routed via broadband matrix
unit 28 to wideband subsystem 16. FIG. 10 is a block diagram of
wideband subsystem 16. Wideband subsystem 16 couples to broadband
subsystem 14 through tributary signal processing units 38.
[0078] Tributary signal processing unit 38 includes a matrix
interface 100 for multiplexing and demultiplexing internal STS-1P
signals to and from internal transmission link 30, respectively.
Tributary signal processors 102 within tributary signal processing
unit 38 convert internal STS-1P signals output from matrix
interface 100 into an internal mapped matrix transport format (MTF)
and vice versa.
[0079] Signal flow to and from wideband center stage matrix 40
occur through a wideband digital matrix unit 103 within tributary
signal processing unit 38. Wideband digital matrix unit 103
includes the originating and terminating stages as the first and
third stages of a three stage wideband cross-connect matrix. The
second stage of the wideband cross-connect matrix is performed by
wideband center stage matrix 40.
[0080] Redundant attached processors (not shown) extract overhead
data as supervised by a unit controller. All tributary signal
processing units 38 include similar configurations for
interconnection with narrowband subsystem 18 and low speed
electrical unit 32.
[0081] For asynchronous payloads, tributary signal processor 102
terminates/creates an internal STS-1P signal that carries a DS-3
mapped synchronous payload envelope, demultiplexes/multiplexes DS-1
signals from/to DS-3 signals, and maps/unmaps DS-1 signals to/from
internal mapped matrix transport format through an internal matrix
payload capacity format.
[0082] For synchronous payloads, gateway functions for both
asynchronous and byte synchronous mapped floating VT1.5 signals are
also provided. Such functions include cross-connecting asynchronous
DS-1 signals to DS-1 asynchronous mapped floating VT1.5 signals,
asynchronous DS-1 signals to DS-1 byte synchronous mapped floating
VT1.5 signals, DS-1 asynchronous mapped floating VT1.5 signals to
DS-1 byte synchronous mapped floating VT1.5, and two synchronous
floating VT1.5 signals. Gateway functions are also provided for
both asynchronous mapped VT signals.
[0083] Low speed electrical unit 32 of wideband subsystem 16
provides the DS-1 network interface to wideband subsystem 16. Low
speed electrical unit 32 terminates DS-1 signals and performs
performance monitoring and formats DS-1 signals for transport to
wideband matrix center stage 40 through tributary signal processing
unit 38.
[0084] A network processor 104 is utilized by low speed electrical
unit 32 for DS-1 line termination. DS-1 signals are terminated and
mapped into an internal matrix payload capacity (MPC) format.
Besides line and path performance monitoring, network processor 104
performs ESF data link monitoring and allows outbound DS-1 signals
to be timed to received DS-1 signals or retimed to the standard
reference frequency (SRF).
[0085] A mapper 106 provides the interface between network
processor 104 and a matrix interface 108. Mapper 106 also provides
the communication path between unit controller 70 and network
processor 104. Mapper 106 interfaces signals mapped into matrix
payload capacity format with internal STS-1P signals.
[0086] Matrix interface 108 is identical to matrix interfaces
previously discussed. Matrix interface 108 terminates internal
transmission link 30 signals and distributes internal STS-1P
signals to mapper 106. Internal transmission link 30 provides the
communication path between a remote low speed electrical unit 32
and tributary signal processor unit 38.
[0087] A local low speed electrical unit, which does not use
internal transmission link 30, may be implemented by removing its
associated tributary signal processor 102, replacing matrix
interface 108 with a wideband digital matrix unit 103, and change
mapper 106 to convert between matrix payload capacity format and
matrix transport format. Unit controller 70 provides an interface
for control signals between administration unit 20 and all
components of low speed electrical unit 32.
[0088] Wideband matrix center stage 40 performs data channelization
and switching functions for all cross-connected data. Wideband
matrix center stage 40 includes a wideband center stage interface
114 and a wideband center stage switch 116. Wideband center stage
interface 114 terminates signals from originating and termination
stages of wideband digital matrix unit 103 within tributary signal
processing units 38 for cross-connecting by wideband center stage
switch 116.
[0089] Wideband center stage interface 114 performs the data
channelization by preparing data for transport through wideband
center stage switch 116, grouping like channels for placement on a
common output, and monitoring path integrity. Wideband center stage
switch 116, in conjunction with wideband digital matrix unit 103,
performs the matrix switching and cross-connection function for
wideband subsystem 16. A unit controller 70 provides the interface
for the control signals between administration unit 20 and all
components of wideband matrix center stage 40.
VII. Narrowband Subsystem
[0090] Wideband subsystem 16 is capable of routing signals to
narrowband subsystem 18. FIG. 11 is a block diagram of narrowband
subsystem 18. Narrowband subsystem 18 couples to wideband subsystem
16, without the need for a network interface, through narrowband
interface unit 44 by an internal transmission link 30. Narrowband
interface unit 44 includes a matrix interface 120 for multiplexing
and demultiplexing internal STS-1P signals to and from internal
transmission link 30. An STS-1 multiplexer 122 converts internal
STS-1 signals into VT signals and converts VT signals into internal
STS-1P signals.
[0091] A narrowband unit controller 124 extracts a payload from the
VT signals received from STS-1P multiplexer 122 for
cross-connection through narrowband matrix unit 48 and ultimate
output to the network through subrate interface unit 46 or other
wideband channels. Narrowband unit controller 124 also maps
payloads from the network into VT signals for ultimate
cross-connection in wideband subsystem 16.
VIII. Broadband Operation
A. Network Optical Signals
[0092] Operation of integrated multi-rate cross-connect system 10
is dependent upon received network signals. Referring to FIG. 6 for
signal flow discussion, inbound data at an OC-3 rate received from
the network optical domain at high speed optical unit 24 of
broadband subsystem 14 is received by optical terminator 80 which
converts the optical signal to an STS-3 electrical signal, recovers
clock and frame information, and checks the quality of the STS-3
signal.
[0093] Next, optical terminator 80 unscrambles and demultiplexes
the STS-3 signal into its three STS-1 component signals and checks
the quality of each STS-1 signal. Overhead bytes are extracted and
processed from each STS-1 signal and are multiplexed and sent to
attached processors 85. Each STS-1 signal is pointer processed, the
STS-1 synchronous payload envelopes (SPE) are extracted, and the
STS-1 signal synchronous payload envelopes are mapped into an
internal STS-1P signal that is timed to the broadband time
base.
[0094] Groomer 82 receives the internal STS-1P signals and performs
switching and protection as instructed by unit controller 70.
Internal STS-1P signals from groomer 82 are routed to matrix
interface 84. Matrix interface 84 checks the quality of each
internal STS-1P signal and inserts internal overhead bytes into the
internal STS-1P signal transport overhead. A plurality of internal
STS-1P signals, preferably twelve, are multiplexed into an STS-12P
electrical signal, which is converted to an optical signal for
output over internal transmission link 30 to broadband matrix unit
28.
[0095] For outbound OC-3 data, matrix interface 84 of high speed
optical shelf 24 receives an optical input from broadband matrix
unit 28 over internal transmission link 30. Matrix interface 84
converts the optical signal into an internal STS-12P electrical
signal, recovers clock and frame information, and checks the
quality of the internal STS-12P signal. Matrix interface 84
unscrambles and demultiplexes the internal STS-12P signal into
twelve internal STS-1 signals.
[0096] Internal overhead bytes are extracted from the internal
STS-1P signal transport overheads and are forwarded to attached
processor 85 and unit controllers 70 for interpretation and
subsequent appropriate action. Internal STS-1P signals are
reconditioned and output to groomer 82. Groomer 82 performs
switching and protection of internal STS-1P signals. Internal
STS-1P signals from groomer 82 are transmitted to optical
terminator 80. Optical terminator 80 checks the quality of each
internal STS-1 signal, inserts appropriate overhead information to
transform the internal STS-1P signals into standard STS-1 signals,
and multiplexes the standard STS-1 signals into an STS-3 signal.
The STS-3 signal is then converted to an appropriate optical signal
for transmission to the network.
B. Network Electrical Signals
[0097] For inbound DS-3 or STS-1 signals at high speed electrical
unit 26, terminator 86 receives network signals at the DS-3 and/or
STS-1 rates. Network processors 88 terminate the respective DS-3 or
STS-1P line rates, map their payloads into an STS-1 synchronous
payload envelope, and wrap their payloads into an internal STS-1P
signal based on broadband subsystem 14 time base.
[0098] DS-3 and/or STS-1 network signals are also sent from
terminator 86 to redundancy switch 90 where one signal is selected
for output to spare network processor 92. Redundancy switch 90 and
spare network processor 92 perform the protection scheme for high
speed electrical unit 26.
[0099] Internal STS-1P signals from network processor 88 are sent
to matrix interface 94 which multiplexes the internal STS-1P
signals into an internal STS-12P signal. The internal STS-12P
signal is converted into an optical signal that contains system
data, a DS-3 overhead, SONET overhead, internal overhead, timing,
control, and status information for transmission to broadband
matrix unit 28 over internal transmission link 30.
[0100] For outbound DS-3 and/or STS-1 signals, matrix interface 94
converts the optical signal from broadband matrix unit 28 over
internal transmission link 30 into an internal STS-12P electrical
signal. Matrix interface 94 demultiplexes the internal STS-12P
signal into twelve internal STS-1P signals for distribution to
network processor 88. For DS-3 signal output, the internal STS-1P
signals are terminated and the DS-3 signal is removed from the STS
synchronous payload envelope. For STS-1 signal output, network
processor 88 leaves the internal STS-1P signal intact but removes
the internal overhead information and inserts the SONET compatible
overhead information. The DS-3 and/or STS-1 signal payloads are
then prepared for transmission to the network by terminator 86.
IX. Wideband Operation
A. Broadband Interface
[0101] For signal flow in wideband subsystem 16, reference is made
to FIG. 10. Inbound data from broadband subsystem 14 over internal
transmission link 30 is received at matrix interface 100 of
tributary signal processing unit 38. Matrix interface 100 converts
the optical signal from internal transmission link 30 into an
internal STS-12P electrical signal, recovers clock and frame
information, and checks the quality of the internal STS-12P signal.
Matrix interface 100 unscrambles and demultiplexes the internal
STS-12P signal into twelve STS-1 signals.
[0102] Internal overhead information is stripped from the internal
STS-1 signals for processing by an attached processor (not shown)
under the control of a unit controller. Each internal STS-1 signal
is output from matrix interface 100 to a separate tributary signal
processor 102.
[0103] Tributary signal processor 102 terminates one internal STS-1
signal that carries either an asynchronous or synchronous payload.
Asynchronous payloads carry DS-3 mapped synchronous payload
envelopes and synchronous payloads carry VT mapped synchronous
payload envelopes.
B. Asynchronous Payloads
[0104] For asynchronous payloads, tributary signal processor 102
terminates the internal STS-1P signal to extract the DS-3 signals.
The DS-3 signals are terminated and associated DS-1 signals are
extracted and mapped into synchronous matrix payload capacity
frames locked to the local system timing.
[0105] FIG. 12 shows an example of mapping in matrix payload
capacity frames for a DS-1 signal. Matrix payload capacity frames
have a structure similar to a VT1.5 signal except that overhead
bytes are used for internal wideband functions. DS-1 signals are
mapped into a matrix payload capacity frame in a similar manner as
defined for a SONET VT1.5 signal.
[0106] Matrix payload capacity signals are mapped into a matrix
payload envelope. Network traffic is transported through tributary
signal processing unit 38 in matrix payload envelope frames that
have been defined for carrying various network signals. The matrix
payload envelope payload will contain the capacity of 36 fields and
an internal overhead field for mapping of various asynchronous
network signals. Each of the fields provides one byte position for
28 channels plus a stuff byte. The stuff byte is used for frequency
justification compatibility. Matrix payload envelopes carry an
STS-1 payload capacity for either VT1.5 or VT2 signals.
[0107] FIG. 13 shows an example of a matrix payload envelope. The
matrix payload envelope is in a byte interleave data format which
is mapped into a bit interleave signal in the form of a matrix
transport format for serial transmission to wideband matrix center
stage 40.
[0108] Signals are transported through wideband matrix center stage
40 in 125 microsecond synchronous frames using the matrix transport
format. FIG. 14 shows an example of the matrix transport format.
Matrix transport format links provide 28 wideband channels, each
channel capable of carrying a VT1.5 or VT2 payload. The matrix
channels are bit interleaved on matrix transport format frames to
minimize delay and storage requirements of the matrix switching
elements.
[0109] A super frame consisting of 24 matrix transport format
frames has been defined to provide a bandwidth efficient means of
transporting certain internal wideband maintenance information. The
matrix transport format frames contain 296 matrix frames
corresponding to the 296 bits (37 bytes) carried in the matrix
channels. Each matrix frame carries one bit for each of the 28
wideband matrix channels plus a frame bit. Matrix transport format
signals are transmitted from tributary signal processor 102 to
wideband digital matrix unit 103 in a serial 68.672 Mbit/s wideband
frequency stream in order to enter the originating stage of the
wideband cross-connect matrix for processing through wideband
matrix center stage 40.
[0110] For outbound data, wideband digital matrix unit 103 receives
the matrix transport format signals at the terminating stage of the
wideband cross-connect matrix and transmits the matrix transport
format signals to tributary signal processor 102. Wideband digital
matrix unit 103 receives matrix transport format signals from
wideband matrix center stage 40 and converts them from differential
signals into single ended matrix transport format signals for
tributary signal processor 102.
[0111] Tributary signal processor 102 demultiplexes the matrix
transport format signals into 28 matrix payload envelope signals
representing the 28 wideband channels. A data plane selection is
made based on performance monitoring of VT parity and channel
overhead for both planes on a channel by channel basis to select
one of the redundant signal paths.
[0112] Matrix payload capacity frames are extracted from selected
matrix payload envelope, signals and further extracted into DS-1
signals. The DS-1 signals are multiplexed into a DS-3 signal and
mapped into an internal STS-1P synchronous payload envelope. The
internal STS-1P signal is constructed and sent to matrix interface
100, which multiplexes twelve internal STS-1 signals into an
internal STS-12P electrical signal. The internal STS-12P signal is
scrambled and converted into an optical signal for transmission to
broadband subsystem 14 over internal transmission link 30.
[0113] The matrix payload capacity frames carry asynchronous
signals mapped using standard SONET asynchronous mappings. By
mapping matrix payload capacity frames into matrix payload
envelopes, additional overhead can be added that was not supported
in the matrix payload capacity format. To reduce storage
requirements, the matrix payload envelopes having a parallel format
are mapped into the serial scheme of the matrix transport format.
The serial scheme requires the storage of only a single bit unlike
multiple storage required for the parallel format of the matrix
payload envelope. Further, framing overhead can be added in the
mapping from matrix payload envelopes into the matrix transport
format.
C. Synchronous Payloads
[0114] For synchronous payloads, tributary signal processors 102
support a wide variety of cross-connections. For instance,
tributary signal processors 102 perform the following
cross-connections--between asynchronous DS-1 signals and DS-1
signals carried in asynchronous mapped VT signals and synchronous
VT signal to VT signal cross-connections.
[0115] For inbound data, matrix interface 100 of tributary signal
processing unit 38 receives optical signals from internal
transmission link 30 and converts the optical signals to an
internal STS-12P electrical signal at matrix interface 100. Matrix
interface 100 performs a quality check on the internal STS-12P
signal and descrambles and demultiplexes the internal STS-12P
signal into twelve internal STS-1P signals. Internal overhead is
retrieved from the internal STS-1P signals and processed by an
attached processor (not shown).
[0116] Each internal STS-1P signal is sent from matrix interface
100 to a separate tributary signal processor 102. Tributary signal
processor 102 frames up and phase aligns the internal STS-1P signal
and selects one of the redundant internal STS-1P signals in
response to quality checks and performance monitoring of the
signals.
[0117] For synchronous VT signal to VT signal cross-connections,
the selected internal STS-1P signal is terminated and the
synchronous payload envelope is extracted and the VT signals in the
synchronous payload envelope are locked to the local time base in
frequency and phase through pointer processing. The VT signals are
mapped directly into a matrix payload envelope prior to mapping
into the matrix transport format.
[0118] For asynchronous mapped VT signals, the VT signals are
terminated and DS-1 signals within the VT signal synchronous
payload envelope are extracted. The DS-1 signal is desynchronized
and mapped into synchronous matrix payload capacity frames. The
matrix payload capacity frames are mapped into the matrix payload
envelope which is subsequently mapped into the matrix transport
format for transport to the originating stage of the wideband
cross-connect matrix within wideband digital matrix unit 103.
[0119] In the outbound direction, the matrix transport format
signal is received at the tributary signal processor 102 through
the wideband cross-connect matrix of wideband center stage 40 and
the terminating stage of wideband digital matrix unit 103.
[0120] For synchronous VT to VT cross connections, tributary signal
processor 102 extracts matrix payload envelope signals from the
matrix transport format. The VT signals are extracted from the
matrix payload envelope and mapped into internal STS-1P signals for
processing by matrix interface 100 and ultimate transmission on
internal transmission link 30.
[0121] For asynchronous mapped VT signals, tributary signal
processor 102 extracts matrix payload envelope signals from matrix
transport format frames and further extracts matrix payload
capacity signals from the matrix payload envelope signals. DS-1
signals are extracted from the matrix payload capacity frames and
desynchronized and asynchronously mapped into VT signals. The VT
signals are mapped into internal STS-1P signals for processing by
matrix interface 100 and ultimate transmission on internal
transmission link 30.
[0122] Tributary signal processors 102 also support the following
cross-connections--between asynchronous DS-1 signals and DS-1
signals carried in asynchronous map floating VT1.5 signals, between
asynchronous DS-1 signals and DS-1 signals carried in byte
synchronous map floating VT1.5 signals, between DS-1 signals
carried in asynchronous map floating VT1.5 signals and DS-1 signals
carried in byte synchronous map floating VT1.5 signals, and between
two synchronous floating VT1.5 signals.
[0123] In the inbound direction, matrix interface 100 receives
optical signals from internal transmission link 30 and processes
the optical signals to produce the internal STS-1 signals as
previously discussed. Tributary signal processor 102 selects an
appropriate one of the redundant STS-1 signals and extracts the
synchronous payload envelope of the internal STS-1 signal. VT
signals in the synchronous payload envelope are locked to a local
time base and frequency and phase aligned through pointer
processing.
[0124] For synchronous floating VT to VT signal cross-connects, the
VT signals are mapped directly into matrix payload capacity frames.
The matrix payload capacity signals are mapped into the matrix
payload envelope which is subsequently mapped into the matrix
transport format for transport through wideband subsystem 16.
[0125] For asynchronous mapped signals, DS-1 signals are extracted
from the VT1.5 payload through destuffing processes and the DS-1
signal is desynchronized to produce a smooth DS-1 signal. The DS-1
signal is mapped into matrix payload capacity frames for subsequent
mapping to the matrix transport format through the matrix payload
envelope.
[0126] In byte synchronous operation, a new DS-1 signal frame is
created and the DS-0 signalling bits and data are mapped into this
DS-1 frame. The DS-1 signals are then mapped into matrix payload
capacity frames. The matrix payload capacity signals are mapped
into the matrix payload envelope which is subsequently mapped into
the matrix transport format for transport through wideband
subsystem 16.
[0127] In the outbound direction, matrix transport format signals
are received by tributary signal processor 102 through the
cross-connect matrix of wideband matrix center stage 40 and
wideband digital matrix unit 103. Matrix payload envelope signals
are extracted from the matrix transport format signals and matrix
payload capacity signals are extracted from the matrix payload
envelope signals.
[0128] For synchronous floating VT signal to VT signal
cross-connects, the matrix payload capacity signal is converted
directly to a VT signal synchronous payload envelope.
[0129] For byte synchronous operation, DS-1 signals are extracted
from the matrix payload capacity signal, each DS-1 frame is
terminated, the DS-1 frame bit, signalling bits, and DS-0 signals
are extracted. A VT synchronous payload envelope phase and
frequency locked to the local wideband timing base is created and a
DS-1 frame bit, signalling bits, and DS-0 signals are mapped into
the VT signal synchronous payload envelope using transmit pointer
processing to account for frequency variations of the outbound DS-1
signal.
[0130] For asynchronous mapped signals, DS-1 signals are extracted
from the matrix payload capacity signal. The DS-1signals are then
mapped into VT signal synchronous payload envelopes based on the
wideband timing base through a stuffing operation.
[0131] After creation of the VT signal synchronous payload envelope
for each of the cross-connects, the VT signals are mapped into an
internal STS-1P signal synchronous payload envelope and mapped into
internal STS-1P signals for transport onto internal transmission
link 30 through matrix interface 100.
X. Narrowband Operation
[0132] For signal flow in narrowband subsystem 18, reference is
made to FIG. 9. Network outbound data from wideband subsystem 16 is
received at matrix interface 120 of narrowband interface unit 44
over internal transmission link 30. Matrix interface 120
demultiplexes traffic on internal transmission link 30 into
internal STS-1P signals. Internal STS-1P signals are terminated at
STS-1 multiplexer 122 and VT signals are extracted from the
synchronous payload envelope. Narrowband controller 124 terminates
the VT (and, if necessary, DS-1) signals and extracts DS-0 signals
for cross-connection at narrowband matrix unit 48 and network
processing by subrate interface unit 46.
[0133] For inbound signals from the network, narrowband controller
124 either maps the received DS-0 signals to DS1 signals to a
matrix payload capacity signal, to DS-1 signals to an asynchronous
floating VT1.5 signal, to DS-1 signals to byte synchronous floating
VT1.5 signals, or directly to a byte synchronous floating VT1.5
signal. The VT/MPC signal created by narrowband controller 124 are
converted into an internal STS-1P signal by STS-1 multiplexer 122.
Matrix interface 100 multiplexes the internal STS-1P signals for
transmission to wideband subsystem 16 over internal transmission
link 30.
XI. Fault Coverage
[0134] Each subsystem of integrated multi-rate cross-connect system
10 provides fault coverage and monitoring for network traffic that
each carry. Equipment fault detection for signals within integrated
multi-rate cross-connect system 10 carrying network traffic are
provided at signal termination points. Fault coverage information
for each internal signal are generated at points where the internal
signals are created and the fault coverage signals are constantly
monitored at the termination points. Fault coverage for all signals
is placed in corresponding overhead fields for each signal.
XII. Summary
[0135] In summary, an integrated multi-rate cross-connect system
incorporates broadband, narrowband, and wideband subsystems within
a single integrated unit. Components within the integrated
multi-rate cross-connect system can be distributed over a wide
geographic area through internal transmission links. Each subsystem
is placed within its own unique timing island to provide a
distributed implementation and allow for synchronization within the
integrated multi-rate cross-connect system. The integrated
multi-rate cross-connect system is capable of handling optical and
electrical signals in domestic and international
configurations.
[0136] Thus, it is apparent that there has been provided, in
accordance with the present invention, an integrated multi-rate
cross-connect system that satisfies the advantages set forth above.
Although the preferred embodiment has been described in detail, it
should be understood that various changes, substitutions, and
alterations can be made herein. For example, a different number of
signal paths may be used in operation of the integrated multi-rate
cross-connect system. Other examples are readily ascertainable by
one skilled in the art and could be made without departing from the
spirit and scope of the present invention as defined by the
following claims.
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