Title of Invention

A METHOD AND SYSTEM FOR MULTICAST DELIVERY OF INFORMATION IN A DSL NETWORK.

Abstract This invention relates to a method for multicast delivery of information in a DSL network comprising the steps of creating transmission paths between a single source port (21) and multiple destination ports (22-28) in a DSL network receiving step (5) information of said source port determining step (6) which of said destination ports is to receive said information and distributing said information from said source port (21) to selective ones of said destination ports (22-28) by employing a digital subscriber line access multiplexer (DBLAM) (20) to duplicate and distribute a single source stream to the selective ones of the destination ports.
Full Text FIELD OF THE INVENTION
The present invention generally relates to network communications and,
more particularly, to a method of ATM multicast distribution at an ATM network
layer.
BACKGROUND OF THE INVENTION
Changing communications demands are transforming the existing public
information network from one limited to voice, text and low resolution graphics
to bringing multimedia, including full motion video, to everyone's home. A key
communications transmission technology that is enabling transformation of
existing public information networks to accommodate higher bandwidth needs is
Asymmetric Digital Subscriber Line (ADSL), a modem technology. ADSL converts
existing twisted-pair telephone lines into access paths for multimedia and high-
speed data communications. ADSL can transmit up to 8 Mbps (Megabits per
second) to a subscriber, and as much as 960 kbps (kilobits per second) or more
in both directions. Such rates expand existing access capacity by a factor of 50
or more without new cable installations.
Asymmetric Digital Subscriber Line ADSL technology involves modems
attached across twisted pair copper wiring in which transmission rates can be up
to 8 Mbps downstream (to the subscriber) and from 16 kbps to 960 kbps
upstream (from the subscriber), depending on line distance, can be achieved.
Asynchronous Transfer Mode ATM is an ultra high-speed cell based data
transmission protocol that may be run over ADSL. A Digital Subscriber Line
Access Multiplexer (DSLAM) is a device that takes a number of ADSL subscriber
lines and concentrates them to a single ATM line. Plain old telephone service
POTS refers to basic analog telephone service. POTS takes the lowest 4 kHz
bandwidth on twisted pair wiring. Any server sharing a line with POTS must
either use frequencies above POTS or convert POTS to digital and interleave with
other data signals.
Audio, video and other information is increasingly being distributed over
networks from a single source to multiple destination points on the network.
Networks have finite bandwidth capacities associated with them. Sending
multiple copies of the same information to multiple destinations can become
demanding on the network and does not constitute an efficient use of resources.
Accordingly, there is a need for implementing a multicast delivery service
in a DSL network to make efficient use of the network.
SUMMARY OF THE INVENTION
A method that provides for multicast delivery of information in a DSL
network includes creating transmission paths between a single source port and
multiple destination ports in a DSL network; receiving information at the source
port; determining which of the destination ports is to receive the information;
and distributing the information from the source port to selective ones of the
destination ports based on the prior referencing step.
A DSL system for providing multicast delivery of information includes
an ATM network layer for sending information; a digital subscriber line access
multiplexer (DSLAM) coupled to the ATM network layer for receiving the
information; and a network control system for controlling selective multiplexing
of the information through the digital subscriber line access multiplexer (DSLAM).
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The advantages, nature, and various additional features of the invention
will appear more fully upon consideration of the illustrative embodiments now to
be described in detail in connection with accompanying drawings wherein:
Fig. 1 is an exemplary digital subscriber line (DSL) system architecture
capable of offering integrated multi-line telephony services such as voice, data
and video.
Fig. 2 is a block diagram of the inventive method of multicast delivery of
information in a DSLAM at the head-end of a DSL network.
Fig. 3 is an example of a multimedia setup request to network to join a
point-to-multipoint ATM virtual circuit.
It should be understood that the drawings are for purposes of illustrating
the concepts of the invention and are not necessarily the only possible
configuration for illustrating the invention.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is a method of ATM multicasting at the ATM
network layer in a DSLAM at the head-end network for the purpose of
distributing information, such as real-time data, video or audio, to the customer
premise equipment CPE. The ATM layer multicast delivery service enables a
source to transmit ATM cells from a single point to multiple destinations (point-
to-multipoint), rather than using traditional broadcast or uni-cast distribution
methods. This can be viewed as an ATM virtual path/virtual circuit with a single
source and multiple destinations. The ATM network layer will deliver the ATM
cells (on a multicast basis) to the destination points specified in the ATM virtual
path/virtual circuit connection profile. By implementing a multicast delivery
service in a DSLAM at the head-end of a DSL network it is possible to make
efficient use of network resources for the purpose of distributing audio, video
and other information to the customer premise.
A DSL system architecture 1 for integrating voice, data and video
services, shown in Fig. 1, is presented as an exemplary DSL environment for
employing the inventive method of enabling video phone communication and
similar multimedia communication over a DSL link. Details of the individual block
components making up the system architecture are known to skilled artisans,
and will only be described in details sufficient for an understanding of the
invention. The system block diagram 1 is composed of several functional blocks.
The system domain is composed of Central Office (CO) Equipment 100 and
Customer Premise Equipment (CPE). The component blocks within the system
domain and their respective interfaces are: customer premise equipment (CPE),
Digital Subscriber Line Access Multiplexer (DSLAM) 9, an ATM switch 2, an IP
router 13 and DSL terminator 12, and a network control system (NCS) 11.
The current customer premise equipment (CPE) 2 includes a DSL modem
unit that interfaces with four separate analog telephones 3-6 over a plain old
telephone service (POTS), a 10Base-T Ethernet connection to a PC desktop
system 7, and an Ethernet or RS-422 connection to a set-top box with a decoder
8 for connection to a television or video display 8'. From the customer's analog
end, the CPE device 2 accepts the analog input from each of the telephones 3-6,
converts the analog input to digital data, and packages the data into ATM
packets (POTS over ATM), with each connection having a unique virtual channel
identifier/virtual path identifier (VPI/PCI). Known to skilled artisans, ATM is a
connection oriented protocol and as such there is a connection identifier in every
cell header which explicitly associates a cell with a given virtual channel on a
physical link. The connection identifier consists of two sub-fields, the virtual
channel identifier (VCI) and the virtual path identifier (VPI). Together these
identifiers are used at multiplexing, de-multiplexing and switching a cell through
the network. VCIs and VPIs are not addresses, but are explicitly assigned at
each segment link between ATM nodes of a connection when a connection is
established, and remain for the duration of the connection. When using the
VCI/VPI, the ATM layer can asynchronously interleave (multiplex) cells from
multiple connections.
The Ethernet data is also encapsulated into ATM cells with a unique
VPI/VCI. The ATM cell stream is sent to the DSL modem to be modulated and
delivered to the DSLAM unit 9.
Going in the other direction, the DSL signal is received and demodulated
by the DSL modem in the customer premise equipment 2 and delivered to
VPI/VCI detection processing. The ATM cell data with VPI/VCI matching that of
the end user's telephone is then extracted and converted to analog POTS to be
delivered to the telephone. The ATM cell data with VPI/VCI matching that of the
end user's Ethernet is extracted and delivered to an Ethernet transceiver for
delivery to the port.
The Digital Subscriber Line Access Multiplexer DSLAM 9 demodulates
data from multiple DSL modems and concentrates the data onto the ATM
backbone network for connection to the rest of the network. That DSLAM
provides back-haul services for package, cell, and/or circuit based applications
through concentration of the DSL lines onto ATM outputs to the ATM switch 10.
The ATM switch 10 is the backbone of the ATM network. The ATM
switch 10 performs various functions in the network, including cell transport,
multiplexing and concentration, traffic control and ATM-layer management. Of
particular interest in the system domain 100, the ATM switch provides for the
cell routing and buffering in connection to the DSLAM, network control system
11 and the Internet gateway (Internet Protocol IP router 13 and DSL terminator
12), and T.1 circuit emulation support in connection with the multiple telephony
links switch 15. A T1 circuit provides 24 voice channels packed into a 193 bit
frame transmitted at 8000 frames per second. The total bit rate is 1.544 Mbps.
The unframed version, or payload, consists of 192 bit frames for a total rate of
1.536 Mbps.
The ATM switch 10 is shown coupled to a program guide server/video
server 16 to satellite 17, radio broadcast 18 or cable 19 networks. The ATM
switch 10 is also coupled over the DSL terminator 12 and IP router 13 pair to
receive Internet Protocol IP packet data from the Internet 14.
The network control system 100 provides for address translation, demand
assignment and call management functions. The Network Control System's
principle function is to manage the DSL/ATM network including the origination
and termination of phone calls. The NCS is essentially the control entity
communicating and translating control information between the class 5 PSTN
switch (using the GR-303 protocol) and the CPE. The network control system
100 is available for other functions such as downloadable code to the CPE, and
bandwidth and call management (e.g., busy) functions, as well as other service
provisioning and set up tasks.
Turning now to Fig. 2, the block diagram 20 illustrates ATM multicasting
at the ATM layer at the head-end of the network for the purposes of distributing
audio, video and other information to the customer premises equipment CPE.
Multicasting is an efficient method of data delivery that simultaneously sends
information to a group of interested destination points. Networks have finite
bandwidth capacities. Sending multiple copies of the same information to
multiple destinations can become demanding on the network and does not
constitute an efficient use of resources.
The DSLAM of FIG. 2 is configured with an ATM trunk port 21 and
multiple destination ports 22-28. The ATM trunk port 21 is a single virtual
path/virtual channel, illustratively assigned a VPI of 39 and a VCI of 12. In this
exemplary ATM multicast/point-to-multipoint distribution information is delivered
from the ATM trunk port 21 to multipoint destinations: ADSL port 1 22, ADSL
port 2 23, ADSL port 4 25 and ADSL port N 28. ADSL port 1 22 is assigned
a VPI of 36 and VCI of 21. ADSL port 2 23 is assigned a VPI of 36 and VCI of
20. ADSL port 4 25 is assigned a VPI of 45 and VCI of 9. ADSL port N is
assigned a VPI of 37 and a VCI of 4.
ATM multicasting can be done at the ATM network layer. The ATM
network layer is responsible for cell header generation and extraction, cell
VPI/VCI translation and cell multiplexing and de-multiplexing. When a cell arrives
at the trunk port it is identified as a channel of video or other information. This
is based upon the arrived cell's VPI/VCI pair indicated in the cell header, which is
a relationship known by the network control system. A connection profile can
be referenced to find the subscribers to this particular ATM virtual circuit. Based
upon the connection profile, ATM cells can be duplicated to the group of
customers subscribing to this channel.
Fig. 3 shows an example of a multimedia setup request to network to join
a point-to multipoint ATM virtual circuit.
The Customer Premise Equipment (CPE) sends a request to the network
for a multimedia program on an ATM signaling virtual circuit (1, FIG.3). The
message is sent to the ATM switch based on the ATM signaling virtual circuit (2,
FIG.3). The message is sent to the Network Control System (NCS) based on the
ATM signaling virtual circuit (3, FIG. 3). The Network Control System (NCS)
determines if the request is valid (4, FIG.3). If it is a valid request, it sends a
request to the Multimedia server for the CPE to join/build a multicast/point-to-
multipoint ATM virtual circuit for the selected channel (5, FIG.3). The Network
Control System (NCS) sends a request to the ATM switch for the CPE to join a
multicast/point-to-multipoint ATM virtual circuit for the selected channel (6, FIG.
3). The Network Control System (NCS) sends a request to the Digital Subscriber
Line Access Multiplexer (DSLAM) for the CPE to join a multicast/point-to-
multipoint ATM virtual circuit for the selected channel (7, FIG. 3). Once this
connection has been made, the multimedia information will flow to one or more
CPE end-nodes (8, FIG. 3).
In order to provide support for the delivery of multimedia services in a DSL
network, an economies of scale needs to be achieved for the service provider in
order to cost effectively deliver these services to the end user. This economies
of scale can be achieved by efficiently using network resources during the
delivery of this multimedia information to the end user. In order to efficiently
deliver multimedia to the end user a concept known as multicast can be
employed in the network. The basic principle of multicast is the delivery of a
single stream of information to many while efficiently using the resources of the
network. It efficiently uses the resources of the network by having the server
only send a single copy of the multimedia program and having downstream
intermediate nodes replicate this program until it reaches the necessary end
users. Broadcasting is ineffective at providing this, unless every end user is
requesting the multimedia.
The ideal place for effective multicasting is at the edge of the network.
The edge device in a Digital Subscriber Line (DSL) network is the Digital
Subscriber Line Access Multiplexer (DSLAM). The DSLAM shall have the
capabilities of setting up point-to-multipoint connections at the ATM layer (i.e., a
multicast connection). By having this function, the DSLAM can replicate data
and send it to multiple subscribers on different ports.
The uniqueness of this invention is the method by which the
multicast/point-to-multipoint ATM virtual circuits are set up for the delivery of
information to the end user. Also, that the system provides the control for the
multicast/point-to-multipoint delivery of information to the end user.
Although the embodiment which incorporates the teachings of the present
invention has been shown and described in detail herein, those skilled in the art
can readily devise many other varied embodiments that still incorporate these
teachings.
WE CLAIM:
1. A method for multicast delivery of information in a DSL network
comprising the steps of:
creating transmission paths between a single source port and multiple
destination ports in a DSL network;
receiving information at said source port;
determining which of said destination ports is to receive said information;
and
distributing said information from said source port to selective ones of
said destination ports based on said step of referencing, said distributing
step including a control system for communicationing and translating
control information, for providing address translation, demand assignment
and call management functions.
2. A method as claimed in claim 1, wherein said step of creating comprises
creating paths between said source port and said destination ports that
can be selectively multiplexed in a digital subscriber line access
multiplexer DSLAM.
3. A method as claimed in claim 1, wherein said step of distributing
comprises multiplexing said source port to said selective destination ports
in a digital subscriber line access multiplexer DSLAM.
4. A method as claimed in claim 1, wherein said step of receiving comprises
receiving said information at an ATM trunk port of a digital subscriber line
access multiplexer.
5. A method as claimed in claim 1, wherein said step of determining
comprises determining which destination ports are associated with users
who have subscribed to receive said information.
6. A method as claimed in claim 1, wherein said step of determining
comprises referencing a connection profile to determine destination ports
for said information.
7. A method as claimed in claim 1, wherein said step of receiving comprises
receiving said information at an ATM trunk port of a digital subscriber line
access multiplexer and said step of distributing comprises multiplexing
said source port to said selective destination ports in a digital subscriber
line access multiplexer DSLAM.
8. A method as claimed in claim 1, wherein said step of receiving comprises
receiving said information at an ATM trunk port of a digital subscriber line
access multiplexer, said step of determining comprises determining which
destination ports are associated with users who have subscribed to
receive said information, and said step of distributing comprises
multiplexing said source port to said selective destination ports in a digital
subscriber line access multiplexer DSLAM.
9. A DSL system for providing multicast delivery of information comprising:
an ATM network layer for sending information;
a digital subscriber line access multiplexer (DSLAM) coupled to said ATM
network layer for receiving said information; and
a network control system for controlling selective multiplexing of said
information through said digital subscriber line access multiplexer
(DSLAM), said control system for communicatloning and translating
control information, for providing address translation, demand assignment
and call management functions.
10.A DSL system as claimed in claim 9, wherein said ATM network layer is
included in an ATM switch.
11.A DSL system as claimed in claim 9, wherein said digital subscriber line
access multiplexer DSLAM comprises an ATM trunk port for receiving said
information from said network layer and destination ports for receiving
said information selectively.
12.A DSL system as claimed in claim 9, wherein said destination ports
comprise ADSL ports.
13.A DSL system as claimed in claim 10, wherein said network control system
comprises a connection profile to determine which of said destination
ports to receive said information from said ATM trunk port.
14.A DSL access system as claimed in claim 9, wherein said digital subscriber
line access multiplexer DSLAM c omprises an ATM trunk port for receiving
said information from said network layer and ADSL ports for receiving said
information from said ATM trunk port.
15.A DSL system as claimed in claim 14, wherein each of said ATM trunk and
ADSL ports is assigned a unique combination of virtual path and virtual
channel identifiers.
This invention relates to a method for multicast delivery of
information in a DSL network comprising the steps of creating
transmission paths between a single source port (21) and multiple
destination ports (22-28) in a DSL network receiving step (5)
information of said source port determining step (6) which of
said destination ports is to receive said information and
distributing said information from said source port (21) to
selective ones of said destination ports (22-28) by employing a
digital subscriber line access multiplexer (DBLAM) (20) to
duplicate and distribute a single source stream to the selective
ones of the destination ports.

Documents:


Patent Number 223909
Indian Patent Application Number IN/PCT/2002/01424/KOL
PG Journal Number 39/2008
Publication Date 26-Sep-2008
Grant Date 23-Sep-2008
Date of Filing 21-Nov-2002
Name of Patentee THOMSON LICENSING S.A.
Applicant Address 46 QUAI ALPHONSE LE GALLO, F-92648 BOULOGNE CEDEX
Inventors:
# Inventor's Name Inventor's Address
1 RICHARDSON JOHN WILLIAM 30 MATTHEW DRIVE, HAMILTON, NJ
2 RAMASWAMY KUMAR 7701 TAMARRON DRIVE, PLAIN-BORO, NJ 08536
PCT International Classification Number H04L 12/00
PCT International Application Number PCT/US01/18755
PCT International Filing date 2001-06-08
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 60/210,257 2000-06-08 U.S.A.