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Claims  |
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What is claim is:
1. A distributed telecommunications switching system, comprising:
a plurality of delivery units for providing subscriber line and/or network
trunk interfaces to receive and transmit call control information and call
traffic information for a particular call, each of said plurality of
delivery units distributed throughout the system to provide a local
switching function for said call traffic information according to
destination and service requirements of said call control information;
a service unit for providing centralized control, management, and
maintenance functions for each of said plurality of delivery units in
order to direct where and how each of said plurality of delivery units is
to deliver said call traffic information in response to said call control
information, said service unit providing said centralized control,
management, and maintenance functions independently and separately from
said local switching function provided by said plurality of delivery
units; and
a distributed center stage switching fabric providing a communication path
between each of said plurality of delivery units and other of said
plurality of delivery units and between said service unit and each of said
plurality of delivery units.
2. The system of claim 1, further comprising:
a plurality of radio frequency transceivers each associated with one of
said plurality of delivery units for receiving and transmitting call
traffic and call control information from and to a plurality of individual
radio frequency portable units associated with each radio frequency
transceiver, each of said plurality of delivery units receiving said call
traffic and call control information from a corresponding originating
radio frequency transceiver and delivering said call traffic information
to an appropriate destination radio frequency transceiver as directed by
said service unit in response to said call control information.
3. The system of claim 2, wherein each of said plurality of delivery units
includes a plurality of radio banks to provide wireless interfaces to
local subscribers.
4. The system of claim 1, wherein said distributed center stage switching
fabric includes a fiber optic ring that provides multiple communication
paths for simultaneous delivery of said call traffic and call control
information for a plurality of calls and a plurality of call types.
5. The system of claim 1, wherein said distributed center stage switching
fabric includes point to point fiber optic connections to provide multiple
communication paths for simultaneous delivery of said call traffic and
call control information for a plurality of calls.
6. The system of claim 1, further comprising:
a local central office associated with each of said plurality of delivery
to allow communications between subscribers served by said plurality of
delivery units and subscribers served by said local central office.
7. The system of claim 1, wherein each of said plurality of delivery
includes a plurality of channel banks to provide wireline interfaces to
local subscribers.
8. The system of claim 1, wherein each of said plurality of delivery
includes a common control element to perform switching of said call
traffic and call control information to and from other of said plurality
of delivery units under the direction of said service unit.
9. The system of claim 1, wherein each of said plurality of delivery units
processes call traffic and call control information in asynchronous
transfer mode cells for transfer of call traffic information between said
plurality of delivery units and call control information between each of
said plurality of delivery units and said service unit.
10. The system of claim 1, wherein said service unit provides various
services to subscribers of the network, said service unit being adaptable
to provide additional services without affecting operation of existing
services.
11. The system of claim 1, wherein each delivery unit includes a cable bank
to accommodate cable television distribution for telecommunications
services.
12. A distributed personal communications services system, comprising:
a plurality of delivery units for providing wireline and wireless
communication interfaces to a plurality of wireless subscribers in order
to transmit and receive call traffic information and call control
information to and from said wireless subscribers, each delivery unit
distributed throughout the system to provide local switching of call
traffic information to and from said wireless subscribers according to
destination and service requirements within said call control information;
a service unit for providing centralized control, management, and
maintenance of each delivery unit to direct where and how each delivery
unit is to deliver said call traffic information in response to said call
control information;
a fiber optic ring for providing a communication path between each delivery
unit and other delivery units and between said service unit and each
delivery unit, each delivery unit including an add/drop multiplexer for
interfacing with said fiber optic ring in order to process and communicate
call traffic and call control information through asynchronous transfer
mode cells; and
a plurality of radio frequency transceivers associated with each delivery
unit for transmitting and receiving said call traffic and call control
information to and from said wireless subscribers, each delivery unit
receiving said call traffic information from a corresponding originating
radio frequency transceiver and delivering said call traffic information
to an appropriate destination radio frequency transceiver as directed by
said service unit in response to said call control information.
13. The system of claim 12, further comprising:
a local central office associated with each delivery unit to allow
communications between a wireless subscriber and a wireline subscriber and
between wireline subscribers.
14. The system of claim 12, wherein each delivery unit includes a channel
bank to allow communications between a wireless subscriber and a wireline
subscriber and between wireline subscribers.
15. The system of claim 12, wherein each delivery unit allows wireline and
wireless communications between local subscribers and subscribers on other
networks including public and private switched telephone network.
16. The system of claim 12, wherein said service unit locates a particular
subscriber and determines that said particular subscriber is capable of
communicating call traffic and call control information destined for said
particular subscriber, said service unit directing a particular delivery
unit associated with a zone of coverage where said particular subscriber
is found to establish a communication path to a particular radio frequency
transceiver within said zone of coverage and associated with said
particular delivery unit and said particular subscriber.
17. The system of claim 16, wherein said service unit controls a transfer
of said communication path between delivery units and radio frequency
transceivers in the event of subscriber movement from one zone of coverage
to a different zone of coverage during a single continuous call.
18. The system of claim 12, wherein said service unit directs a specific
delivery unit associated with an originating subscriber to establish an
originating connection path for call traffic and call control information
from said originating subscriber.
19. The system of claim 18, wherein said service unit controls a transfer
of said originating connection path between delivery units and radio
frequency transceivers in the event of subscriber movement from one zone
of coverage to a different zone of coverage during a single continuous
call.
20. The system of claim 12, wherein said service unit performs database
queries and initiates call setup procedures for call traffic information
destined for external wireline or wireless networks in response to said
call control information.
21. A distributed telecommunication switching system, comprising:
a plurality of delivery units each operable to provide at least one of a
plurality of telecommunication services, each of said plurality of
delivery units being distributed throughout the system and operable to
provide a switching function for information to other delivery units
according to a telecommunication service associated with said information
and according to destination requirements of said information;
a service unit operable to provide control, management, and maintenance
functions for each of said plurality of delivery units, said service unit
operable to direct how each of said plurality of delivery units is to
perform said plurality of telecommunication services said service unit
providing said control, management, and maintenance functions
independently and separately from said switching function provided by said
delivery units; and
a fiber optic ring operable to provide a communication path for said
plurality of delivery units and said service unit.
22. The distributed telecommunications switching system of claim 21,
wherein said plurality of services include broadband, conventional
telephone, video, and wireless services.
23. The distributed telecommunications switching system of claim 21,
wherein one of said plurality of delivery units provides different
services than another of said plurality of delivery units.
24. The distributed telecommunications switching system of claim 21,
wherein said fiber optic ring has a bandwidth allocated to support
concurrent multiple services and concurrent multi-service transport of
said information.
25. The distributed telecommunications switching system of claim 24,
wherein each of said plurality of delivery units dynamically allocates
said bandwidth of said fiber optic ring according to said information and
services associated with said information.
26. The distributed telecommunications switching system of claim 21,
wherein said service unit and said plurality of delivery units are
adaptable to provide additional telecommunication services without
affecting operation of existing telecommunication services.
27. The distributed telecommunication switching system of claim 21, wherein
said fiber optic ring provides multiple communication paths between said
plurality of delivery units to allow for multiple transfers of information
among said plurality of delivery units. |
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Claims |
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Description |
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TECHNICAL FIELD OF THE INVENTION
The present invention relates in general to telecommunications systems and
more particularly to a distributed telecommunications switching system.
BACKGROUND OF THE INVENTION
The trend in telecommunication systems of today is toward increased
mobility, as evident in the cellular environment where nearly ninety
percent of new cellular phone sales are portable units. However, portable
cellular phones require relatively high power, have a limited talk time
duration, and are relatively high in price for a subscriber. Further, the
transmission path for cellular traffic goes from a radio port to a radio
port controller where it travels through a private line facility through a
local central office to a central switching facility. The central
switching facility switches the call traffic to a nearby central office
where it is trunked back to the local central office for termination. Such
a roundabout switching path is expensive and time consuming in operation.
Telecommunication subscribers demand small, light weight, hand held
portable phones with longer talk times and lower power requirements at a
lower cost to the subscriber. The demand and trend has led to a personal
communications service, a tetherless local access service that will serve
a variety of business and residential communities of interest. However,
presently discussed personal communication networks are dependent upon
conventional wireline switching systems similarly used with cellular
traffic. These conventional wireline switching systems employ centralized
switching facilities which cause the lengthy switching path described
above. Therefore, it is desirable to have a distributed telecommunications
switching system that can provide a calling service through low power,
long talk time, hand held portable communication devices that avoids the
centralized switching facility requirement.
From the foregoing, it may be appreciated that a need has arisen for a
distributed telecommunications switching system that can process call
information without the use of a centralized switching facility. A need
has also arisen for a specific application of a communications network in
the form of a personal communications service network that can provide
improved service to telecommunication subscribers. Further, a need has
also arisen for a personal communications service network that can utilize
existing wire line equipment while implementing its own switching
architecture. Additionally, a need has arisen for a personal
communications service network that has a minimal dependency upon local
exchange carriers and centralized switching facilities.
SUMMARY OF THE INVENTION
In accordance with the present invention, a distributed telecommunications
switching system is provided which substantially eliminates or reduces
disadvantages and problems associated with conventional telecommunication
systems.
According to an embodiment of the present invention, there is provided a
distributed telecommunications switching system that includes a plurality
of delivery units to provide network telephony interfaces and radio system
interfaces in order to receive and transmit call information to and from
wire line and wireless communication devices. Each delivery unit provides
call information to destination communication devices by local switching
through other delivery units or other personal communications networks. A
service unit provides centralized control, administration, operations, and
maintenance for all delivery units under its control in order to direct
where and how each delivery unit is to deliver the call information.
The distributed telecommunications switching system of the present
invention provides various technical advantages over conventional
telecommunication systems. For example, one technical advantage is
co-locating the delivery units that provide call information switching
within each community of interest or geographical area where a significant
quantity of service traffic is originated or terminated. Another technical
advantage is in reducing dependency upon local exchange carriers by
providing separate switching, independent service transport, and
intelligent network services. Yet another technical advantage is in having
a service unit to provide centralized control of the delivery units and
their distributed switching. Still another technical advantage is in
having centralized service management capabilities. Other technical
advantages are readily apparent to one skilled in the art from the
following figures, descriptions, and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
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:
FIG. 1 illustrates a block diagram of a distributed telecommunication
switching system;
FIG. 2 illustrates a block diagram of a conventional switching system as
compared to the distributed telecommunication switching system;
FIG. 3 illustrates a block diagram of an example of switch connections
within the distributed telecommunication switching system;
FIG. 4 illustrates a simplified diagram of an architecture applying the
distributed telecommunications switching system within a personal
communications service environment;
FIG. 5 illustrates a block diagram of a service unit within the personal
communications service environment;
FIG. 6 illustrates a block diagram of a delivery unit within the personal
communications service environment;
FIG. 7 illustrates a block diagram of a common control element within the
delivery unit;
FIG. 8 illustrates a block diagram of a radio bank within the delivery
unit; and
FIG. 9 illustrates a block diagram of a radio frequency transceiver
providing information to the radio bank.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a block diagram of a distributed telecommunications switching
system 10. Distributed telecommunications switching system 10 includes a
service unit subsystem 12 that provides control and management on an
advanced intelligent network (AIN) service platform using information
network architecture (INA) software design principles. Distributed
telecommunications switching system 10 also includes a plurality of
delivery unit subsystems 14 that provide the message transport mechanism
for call information under the control and direction of service unit
subsystem 12. Service unit subsystem 12 and delivery unit subsystems 14
communicate with one another through a fiber optic ring 16. Call
information is transported between delivery unit subsystems 14 and between
service unit subsystem 12 and each delivery unit subsystem 14 on fiber
optic ring 16 in asynchronous transfer mode (ATM) cell format.
Service unit subsystem 12 provides the control and management functions for
distributed telecommunications switching system 10 and is separated from
the transport mechanism function of delivery unit subsystem 14. This
separation of functionality allows service unit subsystem 12 and delivery
unit subsystem 14 to independently evolve and be upgraded to support new
services or new technologies for unique enhancements to service unit
subsystem 12 or delivery unit subsystems 14. Service unit subsystem 12 can
support multiple types of delivery unit subsystems 14 that can provide
multiple services including broadband, video, conventional telephone, and
personal communications services. Service unit subsystem 12 and delivery
unit subsystems 14 of distributed telecommunications switching system 10
may be geographically grouped within a single area or geographically
disbursed in several remote areas while maintaining the distributed nature
of the switching function performed.
FIG. 2 is a block diagram comparing a conventional switch architecture 11
with the architecture of distributed telecommunications switching system
10. Conventional switch architecture 11 includes a common control unit 13
that communicates to trunk units 15 through a control bus 17. Trunk units
15 interface with each other through a matrix 19 having a center stage 21.
Distributed telecommunications switching system 10 is classified into
three types of subsystems--a service unit subsystem 12, a delivery unit
subsystem 14, and a distributed center stage switching subsystem 18.
Distributed center stage switching subsystem 18 allows communication
between service unit subsystem 12 and delivery unit subsystem 14 and
between multiple delivery unit subsystems 14 through fiber optic ring 16
having add/drop multiplexers (ADM) 20 to interface with each subsystem.
Information received by and transmitted from delivery unit subsystem 14 is
time slot interchanged prior to and after transmission to and from fiber
optic ring 16 and add/drop multiplexer 20, respectively, of distributed
center stage switching subsystem 18. Distributed center stage switching
subsystem 18 allows for the replacement of the center stage matrix 21 and
control bus structure 17 found in conventional switching architecture 11
through the use of fiber optic ring 16.
The centralized control and management provided by service unit subsystem
12 allows an end user to be connected to different delivery unit
subsystems 14 while maintaining a common directory number. Conventional
switching systems would require two directory numbers in order to connect
an end user to two different switches. Service unit subsystem 12 exceeds
telecommunications reliability requirements by providing fault tolerance
such that single point failures can occur without loss of information.
Service unit subsystem 12 also provides a centralized control for
services, connection, maintenance, and external signaling interfaces to
other switching systems.
Delivery unit subsystem 14 provides the switching fabric for distributed
telecommunications switching system 10. Distributed telecommunications
switching system 10 can support multiple delivery unit subsystems 14 that
can provide a multitude of services. These services include broadband
interfacing, cable applications, telephony interfacing, and personal
communication services. Delivery unit subsystems 14 may be dedicated to a
specific type of service or multiple services may be accommodated within a
single delivery unit subsystem 14.
Distributed center stage switching subsystem 18 allows for communication of
service control, user traffic transport (including video, data, image, and
voice), and operations, administration, maintenance, and provisioning
(OAM&P) message transport through fiber optic ring 16. Fiber optic ring 16
provides quality information transmission and dual physical path
transmission capability. Information may be transmitted between subsystems
along one portion of fiber optic ring 16, leaving other portions of fiber
optic ring 16 available for simultaneous transmissions between other
subsystems within distributed telecommunications switching system 10.
Distributed center stage switching subsystem 18 can dynamically allocate
and reallocate bandwidths for fiber optic ring 16 transmission in order to
handle times of increased information transmission demand. The bandwidth
of fiber optic ring 16 may also be allocated to support concurrent
multiple services and concurrent multi service transport and allow for
simultaneous use of a specific bandwidth during simultaneous transmissions
on different portions of fiber optic ring 16.
FIG. 3 is a block diagram of an example of switch connection routing for
distributed telecommunications switching system 10. Each delivery unit
subsystem 14 performs switching connections for end users in a switch
function 22 and the ATM cell adaptation in an ATM adaptor 24 in order to
interface with fiber optic ring 16 of distributed center stage switching
subsystem 18. For an intra-delivery unit call connection, switching
function 22 connects end user 1 with end user 2 within delivery unit B
without the necessity of interfacing with fiber optic ring 16. This
intra-delivery unit call connection is performed by all delivery unit
subsystems 14 with corresponding end users for the origination and
destination of a call.
For an inter-delivery unit call connection, end user 3 originates a call
that is processed by its corresponding delivery unit C. Switch function 22
of delivery unit C makes the appropriate connection to ATM adapter 24 and
subsequent placement of information on fiber optic ring 16. Distributed
center stage switching subsystem 18 selects a primary path 16a for
information transmission to destination delivery unit D. Distributed
center stage switching subsystem 18 also allocates an appropriate
bandwidth for transmission of information on primary path 16a of fiber
optic ring 16. Destination delivery unit D receives the call information
and performs translation at ATM adapter 24 and connection at switch
function 22 to appropriate end user 4.
In the event that primary path 16a is damaged or unavailable, call
information transmission from delivery unit C to delivery unit D may still
occur along secondary path 16b. Distributed center stage switching
subsystem 18 allows for dual path interconnection of subsystems in order
to provide continuous operation of switch connections for overcoming any
breaks or cuts in fiber optic ring 16. If call information can flow
through primary path 16a, the portions of fiber optic ring 16
corresponding to secondary virtual path 16b can be available for use by
other delivery units for simultaneous transmission of multiple sets of
call information at the same allocated bandwidth in order to increase the
transmission capacity of fiber optic ring 16.
For calls made between delivery unit subsystems 14 of different distributed
telecommunications switching systems, the call connection can be made as
in delivery unit B or delivery units C and D with originating end users 1
and 3 and end users 2 and 4 as remote destination delivery units,
respectively. The originating end user, the destination end user, and the
link between separate delivery unit subsystems determine the appropriate
connections for the call between different telecommunications switching
systems.
FIG. 4 is a block diagram of a specific application of distributed
telecommunications switching system 10. FIG. 2 shows a distributed
personal communications service (PCS) system 30 for operation within a
particular service area composed of multiple service communities of
interest. Distributed PCS system 30 includes a service unit 12 that
communicates to a plurality of delivery units 14. Delivery units 14
receive and transmit call information from and to a plurality of radio
frequency transceivers 32 as well as conventional wireline facilities.
Radio frequency transceivers 32 receive call information from originating
lightweight, portable personal telephone units 17 within a specific zone
of coverage 36 and transmit call information to similar portable personal
telephone units 34 as determined by delivery units 14 and service unit 12.
All delivery units are interconnected by a fiber optic ring 16 as shown.
Delivery units 14 may also receive and transmit call information through
local central offices 38 co-located with each delivery unit 14 within a
specific community of interest.
Service unit 12 is shown in a logical centralized configuration but still
physically couples to fiber optic ring 16 as previously described. Service
unit 12 communicates with each delivery unit 14 and also communicates with
other wireless networks 40, wire line networks 41, and mobility databases
42, through an SS7 signalling network 43. Service unit 12 also
communicates with a network manager 44 to enable external operations and
maintenance activities.
Service unit 12 communicates with a service creation environment (SCE) and
service management system (SMS) processor 45 to enable development of
reusable services in order to minimize the development cycle, and
significantly increase the speed and reliability of new service
deployment. Service unit 12 employs advanced intelligent network (AIN) and
information network architecture (INA) concepts enabling rapid service
introduction through application modularity, reusability, and portability.
The modularity aspect of distributed PCS system 30 allows for operating a
variety of hardware and software products developed and modified by
different vendors at different times. Service unit 12 and delivery units
14 are designed according to Information Network Architecture (INA)
principles that separate service control from service delivery
functionality. The separation of service control from service delivery
allows distributed PCS system 30 to evolve as new services are developed
and additional services are provided.
In operation, distributed PCS system 30 handles calls to and from wireless
personal telephone units 34. Call information is transmitted from an
originating personal telephone unit 34 to an originating radio frequency
transceiver 32 within a zone of coverage 36 of personal telephone unit 34.
Call information is transferred from originating radio frequency
transceiver 32 to an originating delivery unit 14. Originating delivery
unit 14 performs the necessary switching operation to deliver the call
information to its appropriate destination as directed by service unit 12.
Service unit 12 provides centralized control, operation, administration,
and maintenance for each delivery unit 14 to assist in the delivery of the
call information.
Originating delivery unit 14 switches the call information to the
appropriate destination delivery unit 14 over fiber optic ring 16.
Destination delivery unit 14 sends the call information to an appropriate
destination radio frequency transceiver 32 for transmission to an
appropriate destination personal telephone unit 34. For destinations
outside distributed PCS system 30 or within a wire line network,
destination delivery unit 14 sends the call information to its associated
central office 38 for transmission over the public switch telephone
network to a wire line telephone or a delivery unit within another
distributed PCS network.
Fiber optic ring 16 is a self healing asynchronous transfer mode (ATM)
synchronous optical network (SONET) ring that provides high speed transfer
of call information along two possible paths to and from origination and
destination delivery units 14. Fiber optic ring 16 forms the center stage
of the distributed telecommunications switching system 10 implemented in
distributed PCS system 30. Fiber optic ring 16 is utilized whenever two or
more delivery units 14 are associated with a call as determined by
applications software within service unit 12. In the event of a fiber cut,
the self healing nature of fiber optic ring 16 provides for virtual path
rerouting for call information transportation. Distributed PCS system 30
has the most power and flexibility when implemented with fiber optic ring
16. However, if distributed PCS system 30 is comprised of a smaller number
of delivery units 14, point to point fiber optic connections may be
implemented in distributed PCS system 30 between delivery units 14 for
call information transmission.
FIG. 5 is a simplified block diagram of service unit 12 showing its various
services and applications. Service unit 12 provides centralized service
and connection management for distributed PCS system 30 using advanced
intelligent network (AIN) concepts. Service unit 12 provides
administrative, maintenance, and network level management, and call
processing functions, including connection, service, and mobility
management. A programmable application computing environment (PACE.TM.)
provides the basis for the service unit 12 component of the distributed
PCS system 30. Service unit 12 communicates with delivery units 14 over a
high speed data link 46 and an add/drop multiplexer interface 47 to the
fiber optic ring 16. Service unit 12 communicates to local exchange
carriers and interexchange carriers of the public switch telephone network
and other networks and databases through SS7 links 48 of the SS7 network
43. The SS7 signaling connection provided by service unit 12 to other
networks and databases 49 allows for call set up to external networks and
database queries and responses.
During processing of a call, service unit 12 controls the alerting process
by establishing that the subscriber unit is capable of communicating and
by directing the appropriate delivery unit 14 to establish a voice
connection to an appropriate radio frequency transceiver 32 for alerting
the subscriber of an incoming telephone call. Calls destined for
subscribers are delivered to the appropriate delivery unit 14 that serves
the radio frequency transceiver 32 in the area where the subscriber is
active. Service unit 12 directs the appropriate delivery unit 14 to
deliver the call to the appropriate radio frequency transceiver 32.
Service unit 12 interacts with internal databases to determine the
subscriber's radio location, status, alerting information, and terminating
features. From information stored within the internal databases, service
unit 12 controls where and how to deliver the call to the subscriber.
Service unit 12 also works with the appropriate delivery unit to provide
originating service for wireless calls. Service unit 12 instructs the
appropriate delivery unit 14 to associate the call origination with the
subscriber and queries the appropriate database for the subscriber's
originating features and controls the delivery unit 14 in providing that
set of features. In the event of subscriber movement from one zone of
coverage 36 to another zone of coverage 36, service unit 12 controls the
actions required to maintain a seamless connection for the call. Service
unit 12 controls the transfer between delivery units 14 by controlling
switch actions of delivery units 14.
Service unit 12 provides the storage, maintenance, access, and control of
the data necessary to provide all the services for distributed PCS system
30. Databases necessary to provide appropriate services include call
processing information, encryption information, radio equipment
configuration, routing instructions, subscriber features, subscriber
location mapping, and subscriber status. The call models, conventionally
placed in the switching modules of a cellular and public switched
telephone network, appropriate for distributed PCS system 30 are centrally
placed within service unit 12. Security provided by service unit 12
includes authentication and registration for the subscribers and
terminals. Service unit 12 also provides operations, administration,
maintenance, and provisioning (OAM&P) functionality through interfaces to
operation support systems 50. Service unit 12 also records and generates
details of the call to ensure accurate billing data. By having a
centralized control, service unit 12 ensures that each delivery unit 14
can support the various services and features for distributed PCS system
30.
FIG. 6 is a simplified block diagram of a delivery unit 14. The switching
functionality for distributed PCS system 30 is distributed around the
service area through delivery units 14 that operate as small switching
modules under the centralized control and management of service unit 12.
Delivery unit 14 is the local access element providing the switching
fabric and network interfaces and interconnected with other delivery units
by fiber optic ring 16. Interfacing of delivery unit 14 to fiber optic
ring 16 is through an ATM add drop multiplexer 20.
Delivery unit 14 includes an integrated radio bank 51, a channel bank 52,
and a fiber bank 54, and a cable bank 55. The use of these different banks
allows for delivery unit 14 to accommodate integration of different radio
technologies and wireline connectivity. Integrated radio bank 51 provides
an interface to a radio frequency transceiver 32 that utilize different
communication links, including fiber, coaxial cable, and copper. A base
station controller 56 may provide an external interface to a radio
frequency transceiver 32 and communicate call information to delivery unit
14 over an integrated services digital network (ISDN) communication link
to channel bank 52. Though shown external to delivery unit 14, base
station controller 56 may be integrated into delivery unit 14 instead of
interconnected via a standard open interface, as similarly shown with
respect to integrated radio bank 51. Delivery unit 14 may also interface
with a radio network unit 58 that receives communication data from a radio
frequency transceiver 32 and relays the data to delivery unit 14 at fiber
bank 54 through a fiber optic connection. Switching service using cable
television distribution may also be provided by delivery unit 14 through
cable bank 55 interface with a cable head 57.
As described above, delivery unit 14 has flexibility to accommodate a
variety of radio technologies. Delivery unit 14 can also support
conventional wire line and switching technology through interfacing with
local exchange carriers and interexchange carriers through a channel bank
59. By providing trunk interfacing to a nearby central office 38, delivery
unit 14 allows for ingress and egress of public, local, and interexchange
network call information without the need for expensive back haul to a
central switch as found in cellular communication transmission.
Co-location of delivery units 14 with central office 38 allows access to
radio resource distribution facilities and unbundling of services for
subscriber specific usage. Delivery unit 14 also has a common control
element 60 to provide local control and management and diagnostic
capabilities. Common control element 60 also provides a local switching
matrix to connect bank channels to bank channels or bank channels to ATM
add drop multiplexer 20 interface to fiber optic ring 16 and stand alone
emergency operation in the event of isolation from service unit 12.
FIG. 7 is a block diagram of common control element 60 of delivery unit 14.
Common control element 60 interfaces with fiber optic ring 16 though an
optical receiver 61 and an optical transmitter 62 that provide modulation
and demodulation of call information for fiber optic ring 16. An add/drop
multiplexer 20 processes call information from and to optical receiver 61
and optical transmitter 62, respectively. A service unit ATM adaptation
layer (AAL) 64 handles communications between service unit 12 and delivery
unit 14. A delivery unit AAL 65 handles call information transfer between
delivery units 14. A SONET framer 66 formats call information for
placement onto fiber optic ring 16 through delivery unit AAL 65 and
provides conversion of call information obtained by optical receiver 61
through delivery unit AAL 65.
Call information to and from SONET framer 66 traverses through a time slot
interchanger 67. Time slot interchanger 67 performs the appropriate
switching for the call information to and from bank control units found in
each of the various banks of delivery unit 14. A control unit 68 includes
clock generation, system memory, and control processor functions to
control operation of delivery unit 14 as directed by service unit 12. A
set of service circuits 69 supervise operation of time slot interchanger
67.
FIG. 8 is a block diagram of an example of radio bank 70 for use in
delivery unit 14. Radio bank 70 has a plurality of line interfaces 72,
each line interface 72 connecting to a corresponding radio frequency
transceiver 32 over a digital link 74. Each line interface 72 also
connects to a selector matrix 76. Selector matrix 76 provides call
information from an appropriate line interface 72 to, and receives call
information for an appropriate line interface 72 from, a plurality of
digital signal processing channels 78. Digital signal processing channels
78 include a call control signaling circuit 82 which are under the control
of a control processor 80. Call control signaling circuit 82 performs
encryption and decryption of call information, transcoding of call
information, fax and data service, as well as other digital signal
processing functions. Each call control signaling circuit 82 within each
digital signal processing channel 80 receives and transmits call
information from and to a bank control unit 84. Bank control unit 84 sends
and receives information to and from time slot interchanger 65 of common
control element 60 in each delivery unit 14.
FIG. 9 is a block diagram of an example of radio frequency transceiver 32
that interfaces with radio bank 70. Radio frequency transceiver 32
receives call information on redundant receivers 90 of one of a plurality
of radio ports 92. Call information is processed by redundant decoders 94
and placed onto signal line 98 by a diversity switch 96. The call
information on signal line 98 is processed by a quality measure circuit
100 and switched by a multiplexer 102 to a line interface 104. Line
interface 104 transmits the call information to radio bank 70 over digital
link 74 according to clock generator 106. For transmission to a wireless
subscriber, call information flows from radio bank 70 on digital link 74
through line interface 104 to multiplexer 102. Multiplexer 102 selects an
available radio port 92 and sends the call information on signal line 98
to an encoder 108. The call information is modulated by a modulator 110
for transmission to the wireless subscriber by power amplifier 112.
Though a specific radio bank and radio frequency transceiver 32 cell site
using time division multiple access (TDMA) technology shown, delivery unit
14 may accommodate other radio banks and radio frequency transceivers
having different radio technologies.
In summary, a distributed telecommunications switching system includes a
service unit that provides centralized control, administration, and
maintenance function for a plurality of delivery units. Each delivery unit
is associated with a central office to support local communities of
interest and provide easy interconnect for local terminating and
originating traffic in a most efficient and economical manner. The
delivery units provide the switching function for the distributed personal
communications network. Each delivery unit within the distributed
telecommunications switching system is tied to each other delivery unit by
a fiber optic ring or through a point-to-point fiber connection. Each
delivery unit receives call information from personal wireless telephone
units through a series of radio frequency transceivers. In a specific
application, each delivery unit also can receive wire line transmissions
through connection with the public switch telephone network or through its
own equipped wireline subscriber interfaces. A delivery unit switches cal | | |
