U.S. patent application number 10/004031 was filed with the patent office on 2002-04-11 for media server interconnect architecture.
This patent application is currently assigned to Time Warner Entertainment Company, L.P., D.B.A. Time Warner Cable. Invention is credited to Adams, Michael Brian.
Application Number | 20020042924 10/004031 |
Document ID | / |
Family ID | 25495771 |
Filed Date | 2002-04-11 |
United States Patent
Application |
20020042924 |
Kind Code |
A1 |
Adams, Michael Brian |
April 11, 2002 |
Media server interconnect architecture
Abstract
An improved media server interconnect to subscriber terminals is
accomplished with a plurality of media servers at a headend where
each media server provides one or more programs for distribution to
the subscriber terminals. An array of modulators connects a
requested media asset, such as a video program or WEB page, from a
media server to a requesting subscriber terminal. A connection
manager responds to a media asset request from the requesting
subscriber terminal and selects a source server to provide the
requested media asset and selects a modulator in the array to send
the requested media asset from the source server to the requesting
subscriber terminal. The array of modulators acts as a two stage
switch between the source server and the requesting subscriber
terminal. A selected modulator in said array is the switch point in
the two stage switch. The connection manager controls a first stage
of the switch by selecting the selected modulator to receive the
requested media asset from the source server. The requesting
subscriber terminal acts as a second stage of the two stage switch
also under the control of the connection manager by tuning to the
channel frequency of the selected modulator. The connection manager
also allocates a media asset identifier to the requested media
asset and notifies the subscriber terminal of the media asset
identifier. The source media server sends the requested media asset
as digital data packets. The source media server inserts the
program identifier in each digital data packet of the requested
media asset. The requesting subscriber terminal, responds to the
media asset identifier in the digital data packets and extracts the
digital data packets of the requested media asset from a data
stream received from the selected modulator.
Inventors: |
Adams, Michael Brian;
(Castle Rock, CO) |
Correspondence
Address: |
Brian P. Kinnear
HOLLAND & HART LLP
555 Seventeenth Street, Suite 3200
P.O. Box 8749
Denver
CO
80201
US
|
Assignee: |
Time Warner Entertainment Company,
L.P., D.B.A. Time Warner Cable
|
Family ID: |
25495771 |
Appl. No.: |
10/004031 |
Filed: |
October 31, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10004031 |
Oct 31, 2001 |
|
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08954672 |
Oct 20, 1997 |
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Current U.S.
Class: |
725/114 ;
348/E7.073; 709/219; 725/116 |
Current CPC
Class: |
H04L 65/1101 20220501;
H04N 7/17336 20130101; H04N 21/2383 20130101; H04L 65/612 20220501;
H04N 21/2225 20130101; H04N 21/2393 20130101; H04L 67/02
20130101 |
Class at
Publication: |
725/114 ;
725/116; 709/219 |
International
Class: |
H04N 007/173; G06F
015/16 |
Claims
What is claimed is:
1. Apparatus for interconnecting media servers to subscriber
terminals in a system having a headend and a distribution network
with a plurality of subscriber terminals connected to the network,
said apparatus comprising: a plurality of media servers at the
headend, each media server providing one or more media assets for
distribution to the subscriber terminals; a plurality of modulators
connecting a requested media asset from a media server to a
requesting subscriber terminal; and a connection manager,
responsive to a media asset request from the requesting subscriber
terminal, selecting a source media server from the plurality of
media servers to provide the requested media asset and selecting a
modulator from the plurality of modulators to send the requested
media asset from the source media server to the requesting
subscriber terminal.
2. The apparatus in claim 1 wherein: said plurality of modulators
acts as switch points in a two stage switch between the source
media server and the requesting subscriber terminal; a selected
modulator operating at its channel frequency in said plurality of
modulators being the switch point in the two stage switch; said
source media server under the control of the connection manager
acting as a first stage of the switch by selecting the selected
modulator to receive the requested media asset from the source
media server; and said requesting subscriber terminal acting as a
second stage of the switch by tuning to the channel frequency of
the selected modulator.
3. The apparatus of claim 2 wherein: said media server sends the
requested media asset as digital data packets; said connection
manager allocates a program identifier to the requested media asset
and notifies the subscriber terminal of the program identifier;
said media server inserts the program identifier in each digital
data packet of the requested media asset; said requesting
subscriber terminal, responsive to the program identifier in the
digital data packets, extracting the digital data packets of the
requested media asset from a data stream received from the selected
modulator.
4. The apparatus of claim 1 wherein said plurality of modulators
comprises: a rectangular array of modulators; each modulator in a
row of modulators in the rectangular array receives a media asset
from a media server linked to the modulator, and each modulator in
a row modulates at the same frequency a media asset from the media
server; each modulator in a column of modulators in the rectangular
array modulates at a different frequency a media asset from a media
server; and a combiner combining all of the modulated media assets
from a column of modulators for distribution to a pre-defined set
of subscriber terminals.
5. The apparatus of claim 4 wherein the pre-defined set of
subscriber terminals is a node group of subscriber terminals.
6. The apparatus of claim 4 wherein each modulator in a row is
linked in parallel with other modulators in the row to the media
server for the row.
7. The apparatus of claim 4 wherein: each modulator in a row is
linked in series with other modulators in the row to the media
server for the row; said media server sends the requested media
asset as digital data packets; said connection manager allocates a
program identifier to the requested media asset and notifies a
selected modulator in the row of the program identifier; and said
selected modulator, responsive to the program identifier, for
modulating the digital data packet of the requested media asset for
transmission to the requesting subscriber terminal.
8. In a method for managing the connection from a media server to a
subscriber terminal to provide a media asset from the media server
to a requesting subscriber terminal, said method comprising the
computer implemented steps of: analyzing a workload at each of a
plurality of media servers and selecting a media server for
supplying the media asset and selecting a transmission path for
passing the media asset from a selected media server to the
requesting subscriber terminal; allocating an media asset
identifier to the media asset; instructing the selected media
server to play the media asset as a media asset stream tagged with
the media asset identifier; sending a reply message to the
requesting subscriber terminal, said reply message containing the
media asset identifier allocated to the media asset and the
transmission path whereby the subscriber terminal has the
information required to receive the media asset.
9. The method of claim 8 further comprising the steps of: acquiring
at the requesting subscriber terminal the transmission path; and
extracting at the requesting subscriber terminal the media asset
stream tagged with the media asset identifier received over the
transmission path whereby the requested media asset is delivered to
the requesting subscriber terminal.
10. The method of claim 8 wherein said analyzing step further
comprises the steps of: selecting a media server to provide the
media asset; and selecting a modulator to modulate at a
predetermined frequency the media asset stream and thereby select
the transmission path to the requesting subscriber terminal.
11. The method of claim 10 wherein the step of selecting a
modulator comprises the step of: providing the media asset stream
on an output port of the media server, said output port being
connected to predetermined modulator.
12. The method of claim 10 wherein the step of selecting a
modulator comprises the step of: providing the media asset stream
to a plurality of modulators; sending to the selected modulator the
media asset identifier allocated to the media asset whereby the
selected modulator, when receiving the media asset stream, will
modulate only the media asset with the media asset identifier.
13. The method of claim 10 further comprising the steps of tuning
the requesting subscriber terminal to the predetermined frequency
of the selected modulator; and extracting at the requesting
subscriber terminal the media asset stream tagged with the media
asset identifier received on the frequency of the selected
modulator whereby the requested media asset is delivered to the
requesting subscriber terminal.
14. Apparatus for interconnecting media servers to subscriber
terminals in a system having a headend and a distribution network,
a plurality of media servers connected at the headend, and a
plurality of subscriber terminals connected to the network, a
requesting subscriber terminal requesting a media asset from the
media servers, said apparatus comprising: each media server
providing one or more media assets for distribution to the
subscriber terminals; an array of modulators modulating requested
media assets provided by the media servers; a plurality of sets of
modulators in the array, a media server linked to each set of
modulators, each modulator in a set modulates at the same frequency
a media asset from the media server linked to the set, and each set
of modulators modulates at a different frequency from other sets of
modulators in the array; a connection manager, responsive to a
media asset request from the requesting subscriber terminal,
selecting a media server as a source media server to provide the
requested media asset and selecting a modulator from the set of
modulators linked to the source media server to modulate the
requested media asset for transmission to the requesting subscriber
terminal through a combiner for a group of subscriber terminals
containing the requesting subscriber terminal; and said combiner
combining all of the modulated media assets from each of the sets
of modulators for distribution to a pre-defined group of subscriber
terminals.
15. The apparatus of claim 14 wherein each modulator in a set is
linked in parallel with other modulators in the set to the media
server for the set.
16. The apparatus of claim 14 wherein: each modulator in a set is
linked in series with other modulators in the set to the media
server for the set; said source media server sends the requested
media asset as digital data packets; said connection manager tags a
program number to the requested media asset and notifies the
selected modulator in the set of the program number; and said
selected modulator, responsive to the program number, for
modulating the digital data packet of the requested media asset for
transmission to the requesting subscriber terminal.
17. The apparatus of claim 14 comprises in addition: said
requesting subscriber terminal tuning to the frequency of the set
of modulators linked to the source media server.
18. The apparatus of claim 17 comprises in addition: said
connection manager tags a program number to the requested media
asset; and said requesting subscriber terminal displaying a media
asset tagged with the program number received on the frequency of
the set of modulators linked to the source media server whereby the
requested media asset is delivered to the requesting subscriber
terminal.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a server interconnect architecture
for supplying Broadband On-Demand Services (for example,
Video-On-Demand (VOD), WEB browsing, etc.) in a communication
network to residential or business communication services
subscribers. More particularly, this invention relates to
selectively interconnecting a plurality of media servers at a
headend in the communication network to subscriber terminals
attached to the network.
[0003] 2. Description of the Related Art
[0004] The state of the art in the delivery of entertainment
services and other services to subscribers is exemplified by a full
service network described in copending, commonly-assigned U.S.
patent application Ser. No. 08/802,833, filed Feb. 19, 1997,
entitled "System and Method For Providing A Full Service Television
System" invented by M. L. LaJoie et al. One embodiment of the
LaJoie et al full service network or cable system is shown in FIG.
1 herein.
[0005] As illustrated in FIG. 1, a preferred full service network 1
comprises five primary components: a headend 2; at least one fiber
transport 3, at least one distribution hub 4; at least one hybrid
fiber coax plant 5; and a plurality of set-top terminals 6. The
set-top terminal 6 is a subscriber terminal in the cable network. A
subscriber terminal is any device connected to a cable network that
provides security, navigation and other services to a subscriber.
The subscriber terminal may be a standalone set-top, or
incorporated into a television, Personal Computer, DVD (Digital
Video Disk) player, or other subscriber equipment.
[0006] Headend 2 provides the primary source of services and
control of system 1. Programs, services and control signals are
delivered to the subscribers' set-top terminals 6 from headend 2 by
transmitting signals through fiber transport 3, distribution hub 4,
and hybrid fiber coax plant 5.
[0007] The subscribers may also interact with the services and
programming provided by headend 2. This is accomplished by set-top
terminals 6 in the subscribers' homes transmitting signals back
through hybrid fiber coax 5, distribution hub 4, and fiber
transport 3 to headend 2. In this way, a two-way, interactive, full
service network is provided.
[0008] In order to provide the services and control of system 1,
headend 2 includes a plurality of digital satellite receivers 10, a
Broadcast Cable Gateway (BCG) 11, a plurality of analog receivers
12, a plurality of Integrated Receiver Decoders (IRD) 13, analog
scrambling and modulation circuitry 20, an Addressable Controller
(AC) 14, a plurality of application servers 15, a plurality of
media servers 16, a digital switch or multiplexer 17, and an
Interactive Cable Gateway (ICG) 18.
[0009] The programs and services generated by headend 2 are
received from primary sources: Digital satellite transmissions from
digital service providers, analog satellite transmissions from
analog service providers, application services on application
servers 15, and media services on media servers 16. Digital and
analog services provide the more traditional forms of television
broadcast services, including services such as television programs
and information services. Application servers provide services,
such as database services, network management services,
transactional electronic commerce services, system administration
console services, application specific services (such as stock
ticker, sport ticker, and weather), resource management services,
connection management services, subscriber care services, billing
services, operation system services, and object management
services. Media servers provide time-critical media assets
including MPEG-2 encoded video and audio, MPEG-2 encoded still
images, WEB pages, bit-mapped graphic images, PCM digital audio,
application programs, and application data files. A media asset is
defined as a collection of one or more of these stream or file
types together with the associated meta-data that binds them
together.
[0010] In order to provide this multitude of cable services to
subscribers over the cable network, the signals are modulated onto
a plurality of 6 MHz Frequency Division Multiplexed (FDM) channels
in the RF Spectrum from 5 MHz through 860 MHz. More specifically,
the 6 MHz FDM channels can be used to carry analog channels with
Vertical Blanking Interval (VBI) signals, Forward Application
Transport (FAT) channels, Forward Data Channels (FDC), and Reverse
Data Channels (RDC). The frequencies of the analog channels are in
the range of 50 to 500 MHz, the FAT channels are in the range of 50
to 750 MHz, and the RDCs and FDCs are in the ranges of 5 to 40 MHz
and 50 to 750 MHz, respectively.
[0011] Digital services are received from satellites by digital
satellite receivers 10. The signals received by digital satellite
receivers 10 arrive in a Quadrature Phase Shift Key (QPSK)
modulated, encrypted MPEG-2 transport stream format. Once the
satellite signals have been received by the digital satellite
receivers, Broadcast Cable Gateway (BCG) 11 converts the signals
for transmission over the cable system's communication network
under the control of addressable controller 14. Broadcast Cable
Gateway 11 demodulates, applies Forward Error Correction (FEC), if
desired, and decrypts the satellite transmission to recover an
MPEG-2 transport stream. The MPEG-2 stream is then manipulated by
BCG 11 to remove unwanted programs from the stream to form an
MPEG-2 payload. BCG 11 then encrypts the payload (if desired), adds
FEC and modulates the payload onto a Forward Application Transport
(FAT) 6 MHz FDM channel. The modulation used on the FAT channels is
preferably 64 or 256 Quadrature Amplitude Modulation (QAM) which
enables the channels to carry digital data at rates typically in
the range of 27 or 38 Mbps, respectively
[0012] Analog programs and services are received from satellite
transmissions by receivers 12 and processed by integrated receiver
decoders 13 and analog scrambler and modulator 20 Analog satellite
receivers 12 typically receive the satellite transmissions from the
analog service providers in a modulated and scrambled NTSC format.
Integrated receiver decoders 13 demodulate and descramble the
satellite signals into NTSC signals, and then analog scrambler and
modulator 20 scrambles using the cable system's scrambling method,
if desired, and modulates the NTSC signals onto an analog 6 MHz FDM
channel. The FDM modulation frequencies and scrambling techniques
used for the NTSC signals are preferably selected to maintain
downward compatibility with analog set-top terminals which may be
already deployed at the time of implementation of the full service
network.
[0013] Application and media programs and services are provided by
application and media servers 15 and 16 under the control of
addressable controller 14 through digital switch or multiplexer 17,
interactive cable gateway 18 and data channel gateways 19 in
distribution hubs 4. The programs and services by servers 15 and 16
are preferably provided in MPEG-2transport stream format.
Addressable controller 14 may oversee the distribution of programs
and services by servers 15 and 16 by processing requests for
programs and services from the set-top terminals, instructing the
servers when, how and where to deliver a requested program or
service and directing the programs and services through the digital
switch or multiplexer 17 to the interactive cable gateway 18 in
headend 2 and the data channel gateways 19 in the distribution hubs
4.
[0014] Digital switch, or multiplexer 17, connects servers 15 and
16 with addressable controller 14, interactive cable gateway 18 and
data channel gateways 19 in distribution hubs 4. Addressable
controller 14 provides control signals to servers 15 and 16,
set-top terminals 6, BCG 11 and Data Channel Gateways (DCGs) 19.
Controller 14 communicates with DCGs 19 and set-top terminals 6 via
Internet Protocol (IP) datagrams through Forward (in the direction
towards set-top terminals 6) and Reverse (in the direction towards
headend 2) data channels.
[0015] Because the programs and services provided by the
application servers 15 typically do not require high bandwidth,
these servers may be connected to digital switch or multiplexer 17
directly (as shown), or via intermediate networks. Media servers
16, however, do require a great deal of bandwidth, and accordingly
are best connected to digital switch or multiplexer 17 directly.
Furthermore, to achieve the high bandwidth requirement, media
servers 16 should incorporate disk drives utilizing interfaces
achieving at least the speeds of SCSI Fast and SCSI wide
interfaces, with Ultra SCSI and Fiber Channel interfaces being
preferred.
[0016] Interactive Cable Gateway (ICG) 18 processes the servers'
signals so that they may be transmitted over the cable system's
communication network. Signals from servers 15 and 16 received at
ICG 18 through digital switch or multiplexer 17 are encrypted, if
desired, subjected to Forward error correction (FEC), if desired,
and modulated onto a 6 MHz FAT channel using 64 or 256 Quadrature
Amplitude Modulation.
[0017] The analog channels, forward application transport channels,
forward data channels and reverse data channels are transmitted
between the cable headend and the set-top terminals over the cable
system's communication network. As shown in FIG. 2, Fiber Transport
3 connects headend 2 to distribution hubs 4. Fiber Transport 3 is a
ring of fiber optic cable connecting multiple distribution hubs 4
to a headend 2. Six strands in the fiber optic cable of Fiber
Transport 3 are usually dedicated to each hub 4 on the ring and
each hub is typically within twenty miles of the headend 2. In
cases in which hub 4 is more than twenty miles from headend 2, an
intermediate hub 4 may be used to repeat the signals in Fiber
Transport 3. By utilizing a ring of Fiber Transport 3, no
distribution hub 4 is cut off from headend 2 by a single break in
fiber transport 3
[0018] Hybrid Fiber Coax Plants 5 connect distribution hubs 4 to
set-top terminals 6. Plants 5 comprise a network of fiber optic
cables 25, a plurality of nodes 26, and a plurality of coaxial
cables 27. A plurality of Radio Frequency (RF) amplifiers (not
shown) may also be required in intermittent spacing throughout
coaxial cables 27 to compensate for losses which occur when the
coaxial cable is split to connect each set-top terminal. Nodes 26
convert the optical signals in fiber optic cables 25 from the
distribution hub 4 into electrical signals for transmission on
coaxial cables 27 to set-top terminals 6. Return signals from
set-top terminals 6 on coaxial cables 27 are converted to optical
signals by nodes 26 for transmission in fiber optic cables 25 to
distribution hubs 4.
[0019] As shown in FIG. 1, each hub 4 comprises a plurality of Data
Channel Gateways 19 which support the Forward and Reverse Data
Channels between hubs 2 and set-top terminals 6. The signals in
Forward and Reverse Data Channels between headend 2 and DCGs 19 are
Internet Protocol datagrams. Between DCGs 19 and set-top terminals
6 these Internet Protocol datagrams may be encrypted and decrypted,
if desired, and QPSK modulated and demodulated. Accordingly, the
Data Channel Gateways 19 include routing, encryption, decryption,
QPSK modulation, and QPSK demodulation functions.
[0020] Referring to FIG. 3, one embodiment of set-top terminals 6
used in the full service network is illustrated. As shown, a
set-top terminal 6 comprises a Central Processing Unit (CPU) 30, a
Memory Management Unit (MMU) 31, a Unified Memory Architecture
(UMA) 32 comprising ROM, NVRAM, Flash ROM, and DRAM, an MPEG
decompression unit 33, an NTSC descramble unit 34, an IP router 35,
a security unit 36, a QAM 64/256 demodulator 37, an NTSC decoder
38, a QPSK demodulate unit 39, a QPSK modulate unit 40, a first
tuner 41, a second tuner 42, a transmitter 43, and NTSC encoder 44,
an RF output 45, a graphics subsystem 46, an S-Video output 47, a
baseband video output 48, an audio subsystem 49, an AC-3 audio
output 50, a baseband audio output 51, an I/O subsystem 52, a
keypad 53, an LED display 54, an IR receiver 55, an IR transmitter
56, an accessories bus interface 57, and a 10-base-T interface
58.
[0021] Controlling the operation of set-top terminal 6 is Central
Processing Unit 30. Preferably, CPU 30 is a processor that can
support 32-bit arithmetic and logical operations that can operate
at speeds of at least 25 MIPs, and that supports a system of
dynamically prioritizable hardware and software interrupts. An
example of a suitable processor for CPU 30 is the SUN MicroSystems
Micro-SPARC core. CPU 30 operates by executing instructions stored
in Unified Memory Architecture 32 under the control of an operating
system such as the Power TV Operating system by Power TV, Inc. of
Cupertino, California CPU 30 accesses UMA 32 through Memory
Management Unit 31. MMU 31 provides memory protection for
application processes and the kernel, and provides a flat address
space for user processes.
[0022] Memory, or UMA, 32 comprises Read Only Memory (ROM), Flash
ROM, Non-Volatile Random Access Memory (NVRAM), and Dynamic RAM
(DRAM). ROM is used primarily for the storage of the operating
system and application software available at the time of
manufacture of set-top terminal 6. At least 1 Mbyte of Read Only
Memory should be provided in UMA 32. Flash ROM is used primarily
for the storage of resident application software, as well as
patches to the operating system and application software. These
patches will be downloaded to set-top terminal 6 from headend 2
after the set-top terminal has been deployed in the subscriber's
home. At least 1 Mbyte of Flash ROM should be provided in memory
32. NVRAM is used primarily for the storage of settings such as
parental control codes, favorite channel line-ups, set-top terminal
setups, channel maps, authorization tables, and Forward Data
Channel address assignments. At least 2 Kbytes of NVRAM should be
provided in UMA 32. Dynamic RAM is used for most application and
operating system storage requirements such as the stack, heap,
graphics, Interactive Program Guide data, channel map, VCR codes,
and marketing data, usage data and functions such as MPEG-2 video
decompression, AC-3 audio decoding, and video manipulation. At
least four Mbytes of Dynamic RAM should be provided in memory
32.
[0023] Frequency Division Multiplexed (FDM) signals from headend 2
are initially received by tuners 41 and 42 through Hybrid Fiber
Coax Plant 5. In-band tuner 41 receives program and services
transmitted to the set-top terminal on analog channels and Forward
Application Transport channels. These programs and services include
analog programs and services from analog satellite broadcasts,
digital programs and services from digital satellite broadcasts,
digital program and services from digital satellite broadcasts,
some digital program and services from the application servers, and
digital program and services from the media servers. NTSC decoder
38 receives the analog program and services from tuner 41 and
produces NTSC baseband signals. QAM 64/256 demodulator 37 receives
the digital services from in-band tuner 41 and demodulates the
signal into MPEG-2 payloads. Out-of-band tuner 42 receives only
incoming IP datagram messages from headend 2 on the Forward Data
Channel. Messages which are transmitted from the headend to the
set-top terminals in Internet Protocol datagrams on the Forward
Data Channel include Interactive Program Guide data messages as
well as other data and control messages. These messages are QPSK
demodulated by QPSK demodulator 39 to reveal the IP datagrams. The
analog NTSC baseband signals, the digital MPEG-2 payloads, and the
digital IP datagrams are descrambled (if necessary), decrypted (if
necessary) and screened by security unit 36. Additionally, security
unit 36 provides encryption, key management, authentication, and
secure transaction functions, and prevents downloading of viruses,
vandalism of software, theft of services, falsified orders,
tampering with the set-top terminal, and direct cloning or
re-manufacturing of the set-top terminal.
[0024] After descrambling, decryption, and screening by security
unit 36, the baseband signals, MPEG-2 payloads, and IP datagrams
are passed on to the analog-to-digital converter 34, MPEG-2
decompression unit 33, and IP router 35. As their names imply, A/D
converter 34 converts the NTSC baseband signals to digital signals;
MPEG-2 decompression unit 33 decompresses the MPEG-2 payloads; and
IP router 35 routes the IP datagrams toward their ultimate
destination.
[0025] Outgoing IP datagram messages are also processed by IP
router 35. After routing the outgoing IP datagrams, security unit
36 screens and encrypts the IP datagrams (if necessary). The IP
datagrams are then QPSK modulated by QPSK modulator 40 and
transmitted to Hybrid Fiber Coax Plant 5 by out-of-band transmitter
43.
[0026] The video and audio outputs of set-top terminal 6 are
generated by NTSC encoder 44, graphics subsystem 46, audio
subsystem 49 and RF modulator 61 NTSC encoder 44 generates S-Video
output 47 and baseband video output 48 from digitized MPEG-2 and
NTSC video. Graphics subsystem 46 produces graphic images and
scales MPEG-2 and NTSC video. Audio subsystem 49 produces the audio
outputs for set-top terminal 6 including AC-3 audio output 50 and
baseband audio output 51. RF modulator 61 generates NTSC RF output
45 necessary to drive a television without S-Video or baseband
inputs from signals received from NTSC encoder 44 and audio
subsystem 49.
[0027] I/O subsystem 52 controls the input and output controls and
the 10-base-T interface 58 for set-top terminal 6. As shown in FIG.
3, I/O subsystem 52 receives inputs from keypad 53, I/R receiver
55, accessories bus 57, and 10-base-T interface 58. I/O subsystem
52 also produces outputs to LED display 54, I/R transmitter 56,
accessories bus 57 and 10-base-T interface 58. Keypad 53 enables
the user to control set-top terminal 6 without requiring the use of
a remote control 59. LED display 54 provides a numeric display for
channel or time indication, and a plurality of single LEDs to
indicate status such as power on, message waiting, set-top output
disabled, etc. I/R receiver 54 is used to receive and digitize
input from remote control 59. I/R transmitter 56 is used to control
a VCR 60 or send updates to remote control 59. Accessories bus 57
is used to connect to external equipment such as a keyboard,
joystick, mouse, I/R transmitter, etc. The 10-base-T interface can
be used to connect to Ethernet interfaces in equipment such as
routers, personal computers, or home entertainment equipment.
[0028] In this full service network, it would be desirable to
provide an improved media server interconnect from the headend to
the set-tops so as to provide more on-demand service versatility
and capacity at reasonable cost.
SUMMARY OF THE INVENTION
[0029] In accordance with this invention an improved media server
interconnect to subscriber terminals is accomplished with a
plurality of media servers at a headend where each media server
provides one or more on-demand programs or services for
distribution to the subscriber terminals. An array of modulators
connects a requested media asset, such as a video program, WEB
page, etc., from a media server to a requesting subscriber
terminal. A connection manager responds to a media asset request
from the requesting subscriber terminal and selects a source server
to provide the requested media asset and selects a modulator in the
array to send the requested media asset from the source server to
the requesting subscriber terminal.
[0030] In another feature of the invention, the array of modulators
acts as a two stage switch between the source server and the
requesting subscriber terminal. A selected modulator in said array
is the switch point in the two stage switch. The connection manager
controls a first stage of the switch by selecting the selected
modulator to receive the requested media asset from the source
server. The requesting subscriber terminal acts as a second stage
of the two stage switch also under the control of the connection
manager by tuning to the channel frequency of the selected
modulator.
[0031] In another feature of the invention, the connection manager
allocates a program identifier to the requested media asset and
notifies the subscriber terminal of the program identifier. The
source media server sends the requested media asset as digital data
packets. The source media server inserts the program identifier in
each digital data packet of the requested media asset. The
requesting subscriber terminal, responds to the program identifier
in the digital data packets and extracts the digital data packets
of the requested media asset from a data stream received from the
selected modulator.
[0032] In another feature of the invention, the array, or matrix of
modulators, is a rectangular array of modulators. Each modulator in
a row of modulators in the rectangular array receives a media asset
from a media server linked to the modulator, and each modulator in
a row modulates at the same frequency a number of media assets from
the media server. Each modulator in a column of modulators in the
rectangular array modulates at a different frequency a media asset
from its media server. A node group combiner combines all of the
modulated media assets from a column of modulators for distribution
to a pre-defined set of subscriber terminals. The pre-defined set
of subscriber terminals is a node group of subscriber terminals. In
one embodiment, each modulator in a row is linked in parallel to
the media server for the row. In another preferred embodiment, each
modulator in a row is linked in series to the media server for the
row. In the latter embodiment, the connection manager allocates a
program identifier to the requested media asset and notifies a
selected modulator in the row of the program identifier. The
selected modulator responds to the program identifier, extracts the
digital data packets and modulates the digital data packet of the
requested media asset for transmission to the requesting subscriber
terminal.
[0033] One great advantage and utility of the present invention is
the ease with which the capacity of the system to deliver on-demand
programs and services may be changed. Also, the present invention
is much less complex than prior media delivery systems providing
the same services. The foregoing and other features, utilities and
advantages of the invention will be apparent from the following
more particular description of a preferred embodiment of the
invention as illustrated in the accompany drawings.
BRIEF DESCRIPTION OF DRAWINGS
[0034] FIG. 1 shows a full service network for providing
entertainment and information services to subscribers.
[0035] FIG. 2 is an example of a fiber-optical/coax cable system
interconnecting the elements of the full service network.
[0036] FIG. 3 is a detailed illustration of a set-top terminal used
in the networks of FIG. 1 and FIG. 2.
[0037] FIG. 4 illustrates one preferred embodiment of invention
showing a plurality of media servers delivering media asset signals
to a modulator array which in turn connects the media asset signals
to node groups of subscriber terminals.
[0038] FIG. 5 shows one preferred embodiment of the modulator array
in FIG. 4.
[0039] FIG. 6 shows another preferred embodiment of the modulator
array in FIG. 4 using Digital Video Broadcast (DVB) standard
Asynchronous Interface (ASI) between media servers and
modulator.
[0040] FIG. 7 illustrates the process flow of control operations
between subscriber terminals and connection management agents in
the media servers in the preferred embodiments of the
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0041] In the preferred embodiment of the invention. as shown in
FIG. 4, a modulator array 70 provides the server interconnect of
media asset signals from the media servers 72 to the fiber
transport 3 for distribution to nodes 26 of set-top terminals 6 In
FIG. 4, elements common to FIGS. 1 and 2 are given the same
reference numerals. Thus, the server interconnect of the present
invention may be used in the full service network of FIGS. 1 and 2,
when modified as shown in FIG. 4.
[0042] The modulator array operates with the subscriber terminals
as a distributed two-stage switch to connect any media server 72 to
any subscriber terminal 6. The first stage is the selection of a
modulator in the modulator array 70 to receive a media or media
asset input from a media server 72. The second stage is the
selection of a modulator (by tuning to a channel or frequency) in
the modulator array by the subscriber terminal 6 to receive the
media asset. The modulator selected by a given media server 72 and
a given subscriber terminal 6 is effectively the switch point in a
two dimensional array of switch points provided by the modulator
array. The selection of server-to-modulator connection and
subscriber terminal-to-modulator connection is performed by a
connection management agent 74 in each media server 72
communicating with the subscriber terminal and the other connection
management agents in the other media servers.
[0043] Modulator array 70, as will be described hereinafter with
reference to FIGS. 5 and 6, includes an array of modulators and a
plurality of node group combiners. The combiners combine signals
from a set of modulators and connect that set of modulators to a
node group. The node group includes a predetermined number of
subscriber terminals and one or more nodes 26. A given subscriber
terminal is in only one node group. All subscriber terminals can
receive a program from any one of the media servers 72. Connection
management agents 74 in media servers 72 send and receive control
information or messages in the form of IP datagrams through digital
switch 17 and interactive control gateway 19. All media assets
provided by the media servers 16 go through the modulator array 70
to the subscriber terminals 6. The media assets do not go through
digital switch 17 and ICG 18, as was previously done in FIG. 1.
Accordingly, digital switch 17 and interactive control gateway 18
are no longer required. Further, the modulator array 70, which is
implemented in one preferred embodiment with QAM modulators and
combiner circuits contains components which are much cheaper than
the components in the digital switch 17 and the interactive control
gateway 18.
[0044] One preferred embodiment of the modulator array 70 is
illustrated in FIG. 5. The media servers 72 in FIG. 4 are depicted
as video servers 76 in FIG. 5. However, it should be understood
that many different types of the media asset will be distributed
from the servers through the modulator array 70 in support of
on-demand service, the typical media asset will be MPEG-2encoded
video and audio, MPEG-2 encoded still images, WEB pages, bit-mapped
graphic images, PCM digital audio, application programs, and
application data files.
[0045] In FIG. 5, modulator array 70 in the preferred embodiment is
made up of a plurality of rows of QAM modulators. Each row is
referred to as a slice or a set, and all modulator in a set
modulate at the same channel frequency and modulate an MPEG-2
formatted data packet from a single server. Modulated signals from
a column of modulators in the modulator array are collected for
transmission over an interactive FAT channel by a combiner for a
given node group of subscriber terminals.
[0046] Video, or media, server 76 provides a selected media asset
to each of the modulators 78, 80 and 82 in slice 1 of array 70. All
modulators in a slice, or set, are linked in parallel to the media
server for that set. A different media asset may be provided to
each of the modulators 78, 80 and 82. The media assets are provided
in the form of digital data packets, and an MPEG program number is
attached to each data packet to identify the media asset contained
in the data packet. Similarly, media server 84 sends the same or
different media asset to each of the modulators 86, 88 and 90
making up slice 2 of the modulator array 70. All of the modulator
in slice 2 are modulating media data packets at the same frequency,
f.sub.2, which is a different frequency from the modulators in
slice 1. There may be any number of slices, i.e., sets or rows of
QAM modulators in the modulator array 70. All modulators in the
same set modulate at the same frequency, and each set of modulators
modulates at a different frequency from the other sets of
modulators. As depicted in FIG. 5, "slice m" with media server 92
and modulator 94, 96 and 98 modulating media data packets at
frequency, f.sub.m, makes up the last set or slice.
[0047] Node group combiners 100, 102 and 104 collect, or combine,
the modulated data packet signals from one modulator in each slice,
i.e. all modulator in a column of the rectangular array 70. There
may be any number of channels (frequencies) combined by a node
group combiner. The number of slices, m, corresponds to the number
of channels m allocated for the media servers to provide programs
to the subscriber terminals.
[0048] The number of node group combiners, and thus the number of
columns in the modulator array 70, depends upon the number of
subscriber terminals to be served. The size of a node group, i.e.
the number of subscriber terminals in a node group, depends upon
the viewing demands of the subscribers in the network. A node group
might typically include 20 nodes with 40 or 50 subscriber terminals
connected to each node. The number of nodes in a node group and the
number of subscriber terminals attached to each node is highly
variable and depends upon the capacity of the communication
components in the network. The size of a node group forms no part
of the invention. However, what is a part of the invention is the
ease with which the capacity of interconnection between servers and
subscriber terminals may be increased. Node groups may be added by
simply adding another column to the modulator array 70. On-demand
capacity to each node group may simply be increased by adding
another slice, i.e , row, to the modulator array 70. In either
case, this may be accomplished by with little, or no, disruption to
service to existing subscribers.
[0049] Each of the media servers 76, 84, 91, and 92 contains a
connection management agent 77, 85, 93 and 95 respectively. These
connection management agents communicate with each other through
control bus 106. The control bus 106 also connects to digital
switch 17 so that the connection management agents may exchange
control messages (IP datagrams) with the subscriber terminals. The
operation of connection management agents will be described
hereinafter with reference to FIG. 7.
[0050] Another preferred embodiment of the invention is illustrated
in FIG. 6. The difference between the embodiments of the invention
in FIGS. 5 and 6 is that in FIG. 6, the modulators in each slice,
or set, are serially connected or daisy-chained to one video or
media server. Each modulator in a set is linked or connected in
series with the other modulators in the set to their media server
using the Digital Video Broadcast Asynchronous Interface (DVB ASI).
The digital data packets for each media asset from the media server
are timed division multiplexed on this serial link from the server
to the modulator in the slice. Each data packet is marked with the
MPEG program number, or media asset identifier, that identifies the
media asset being carried by the data packet. Each modulator in the
slice reads the MPEG number in the digital data packets in the data
stream and extracts the digital data packet that is to be modulated
by the modulator. A control signal goes from the media server to
each modulator notifying the modulator of the MPEG number of data
packets that it is to modulate. Otherwise, the operations of the
server interconnection to node groups by array 70 in FIGS. 5 and 6
are the same. In summary, the media servers select a modulator for
each media asset, and each slice, or set, uses modulator at a
different channel frequency. The column of modulator is collected
by a node group combiner so that any subscriber terminal in a node
group may select a program being provided from any server.
[0051] The operation of the connection management agents with the
subscriber terminals, to provide a requested media asset to a
requesting subscriber terminal is shown in the logical operations
of FIG. 7. The operations in the left column of FIG. 7 are
performed by the connection management agent and the operations in
the right column are performed by a given subscriber terminal
requesting a particular media asset. The logical operation begins
with the subscriber terminal in operation 110 requesting a media
asset, such as a video program, or web page, and sending this
request as an Internet protocol datagram over a reverse data
channel back through the ICG 18 to digital switch 17 to the
connection management agents 74 (FIG. 4). Each connection
management agent receives the request for the media asset at
receive module 112. Analysis operation 114 analyzes availability of
the media asset at its server and the loading, or workload, of the
various media servers in the network.
[0052] Each media server computing system 72, when running the
connection management agent, maintains a media server utilization
table indicating the utilization of each media server 72. Each
connection management agent 74 in each server 72 updates entries in
this table for its server, the updates are transmitted and received
by the other agents and used to update their media server
utilization table. Accordingly, analysis operation 114 first
identifies whether the requested media asset is available at its
server. If it is not, this connection management agent cannot reply
to the request from the subscriber terminal. The connection
management agents in the set of servers, where the media asset is
available, identify a subset of servers with the available program
that, in addition, have available modulator bandwidth, i.e.
modulators, for providing the media asset to the subscriber
terminal. Next, in this subset of servers, the connection
management agents identify the server with the modulator that is
least loaded, i.e. smallest workload, by the current demands on the
network.
[0053] Based on this internal process, the analysis operation 114
then selects a server and a modulator communicating with the node
group containing the subscriber terminal. The selection of a server
defines the frequency, f.sub.y, that the media asset will be
transmitted on, since all modulators for a given server use the
same modulation frequency. In the embodiment of FIG. 5, selecting a
modulator is accomplished by selecting a server output port
connected to that QAM modulator. In the embodiment of FIG. 6,
selecting a modulator is accomplished by identifying a modulator
that will be subsequently instructed in operation 119 to operate on
the MPEG program stream.
[0054] Operation 116 allocates a media asset identifier, or an MPEG
program number, #X, to the requested media asset. This MPEG program
number is a program identifier; it allows the subscriber terminal
to identify the required PIDs (Packet IDentifiers) using the MPEG
Program Specific Information (PSI) transmitted with each data
packet of the media asset as the media asset is transmitted.
Instruct server operation 118 in the connection management agent
instructs the server that when it plays the media asset it is to be
played as an MPEG program, or media asset, stream tagged with the
allocated MPEG program number from allocation operation 116.
[0055] Instruct modulator operation 119 is only executed in the
embodiment of FIG. 6. Operation 119 sends a message to the
modulator selected in operation 114. The message contains the
allocated MPEG program #X and instructs the modulator to modulate
the MPEG program stream tagged with MPEG program #X. In this way,
the appropriate MPEG program stream is switched for transmission to
the node group containing the subscriber terminal.
[0056] Reply operation 120 in the connection management agent in
the selected server sends a reply message to the subscriber
terminal requesting the media asset. The reply message contains the
allocated MPEG program number, #X, and the channel frequency,
f.sub.Y, for receiving the requested media asset. This reply is
passed over control bus 106 to the switch 17 through the DCG 19 and
out over the network through the hubs, through the nodes and to the
subscriber terminal.
[0057] The connection management agent in operation 121 begins to
play the media asset out from the server as an MPEG-2 program
stream. The string of digital data packets for the requested media
asset are tagged with the MPEG program number #X. These data
packets are sent to the selected modulator in the node group for
the subscriber terminal.
[0058] At the subscriber terminal, the reply from the connection
management agent is received at operation 122. The subscriber
terminal now knows that it must tune to the selected channel
frequency, f.sub.Y+L, and look for data packets with the allocated
MPEG program number, #X. The subscriber terminal in operation 123
tunes to frequency, f.sub.Y, to receive the MPEG program stream on
that frequency. Extract operation 124 looks for an MPEG program
stream tagged with MPEG program #X. When the tag is found, the MPEG
program stream so tagged is extracted. Operation 124 then displays
the media asset requested by the terminal subscriber which is now
being received in the tagged MPEG program stream.
[0059] While a plurality of embodiments for implementing the
invention have been described, it will be appreciated that any
number of additional variations or alterations in the elements used
to implement the invention may be made and are within the scope of
the invention as claimed hereinafter.
* * * * *