Note: Descriptions are shown in the official language in which they were submitted.
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SYSTEM MANAGER WITH HYPERTEXT CONTROL INTERFACE FOR
INTERACTIVE CABLE TELEVISION SYSTEM
Field of Invention
The invention relates to cable television systems, and more particularly to
such systems capable of providing interactive services provided over a cable
television network.
Background Art
Bandwidth problems have long restricted the ability of cable television
systems to provide information services to subscribers. Although a coaxial
cable
system may permit a cable system operator to provide, for example, 50
television
channels, each 6 MHZ wide, with a total bandwidth of 300 MHZ, this total
bandwidth is insufficient to permit an arrangement wherein each subscriber may
have, in addition to these 50 channels, an interactive information service
that
functions independently of interactive information services to all other
subscribers and provides full color video, motion typical of movies or
television,
and sound.
The reason for the insufficiency in bandwidth is apparent on a
consideration of the demands on the system. Typically a subscriber on a cable
system obtains information services over a communication path that starts at
the
head end, proceeds over one of typically a number of trunks, and then over one
of a number of feeders, and then over one of a number of taps. Each feeder may
have, for example, fifty or more subscribers, and each trunk might serve a
hundred or more feeders. The result is that 5000 subscribers per trunk is not
atypical. Thus merely to provide a private one-way information service, and
nothing else, to each of these 5000 subscribers would require the trunk to
carry
5000 different signals, each using about 6 MHZ of bandwidth, and would alone
require a trunk bandwidth of 30 GHz, which is nearly two orders of magnitude
greater than provided by a typical coaxial cable system.
The use of fiber optic trunks can assist in providing additional bandwidth.
but to the extent that coaxial cable secondary trunks and feeders are used in
a
hybrid fiber-cable system, bandwidth limitations may continue to pose
problems.
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While video compression schemes may assist in bringing the bandwidth
requirements within more practical limits, each subscriber would then need to
be
provided with his own decompression unit.
Another problem lies in how to handle the switching and computing
demands on the head end to provide separate and private information service to
potentially hundreds of thousands of subscribers simultaneously.
One approach to the above problem involves placing a digital computer in
the home of each subscriber to provide interactive service, where the computer
operates over a traditional network of computers. However, with the above
approach, a large capital investment is needed to provide each subscriber with
a
computer.
Summary of the Invention
In a preferred embodiment, the present invention provides a system
manager for use with an interactive cable system. The cable system has (i) an
information service network for delivering information services to subscriber
televisions, (ii) a plurality of home interface controllers, each home
interface
controller associated with a subscriber television and having a data
transceiver
operative over a data communications link to the headend, (iii) a plurality of
subscriber selection devices, each such device associated with a home
interface
controller and in communication with the data transceiver thereof, for
permitting
subscriber interaction, and (iv) a plurality of interactive controllers,
disposed at
the headend, each interactive controller in assignable television
communication
over the network with a subscriber television and in data communication with a
subscriber selection device.
The system manager has a call set-up server to receive and handle an
initial data exchange with a calling home interface controller; and a first
service
allocation server to pass communication and control associated with the
calling
home interface controller to one of a plurality of first application
processors, each
first application processor being one of the interactive controllers, to
provide a
first information service; wherein the call set-up server and the first
service
allocation server operate as independent processes.
In a further embodiment, the system manager also has a second service
allocation server to pass communication and control associated with a home
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interface controller seeking a second information service to an available one
of a
plurality of second application processors. Each second application processor
is
one of the interactive controllers, and provides the second information
service.
The second service allocation server operates as an independent process. The
first
service allocation server maintains a list of available first application
processors
and the second service allocation server maintains a list of available second
application processors.
In a further embodiment, (1) an interactive controller in assigned
television communication with the calling home interface controller causes
display on the subscriber television associated with the calling home
interface
controller of a page having at least one hyperlink to an additional page and
(2)
selection of such a hyperlink by the selection device associated with the
calling
home interface controller causes a transfer (which may be direct or indirect)
between one of the first and second service allocation servers to the other of
them
so as to cause a change in the information service provided to such subscriber
television. In this embodiment, the page and the additional page are created
in
HTML format, although any hyperlink arrangement may be employed. The effect
is that a subscriber may use an Internet browser type of display to choose
among
various information services, not just Internet service.
In an alternative embodiment of the invention, there is provided a cable
system having (i) an information service network, for delivering information
services to subscriber televisions, (ii) a plurality of home interface
controllers,
each home interface controller associated with a subscriber television and
having
a data transceiver operative over a data communications link to the headend,
(iii)
a plurality of subscriber selection devices, each such device associated with
a
home interface controller and in communication with the data transceiver
thereof, for permitting subscriber interaction, and (iv) a plurality of
interactive
controllers, disposed at the headend, each interactive controller in
assignable
television communication over the network with a subscriber television and in
data communication with a subscriber selection device. The subscriber
selection
device may communicate over the data link each time a cursor movement or
other selection activity is effectuated; alternatively, the data link can
cause
periodic transmission of cursor coordinates when a critical selection activity
has
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occurred, such as pressing a "select" button.
The system manager has a first service allocation server to pass
communication and control associated with a calling home interface controller
to
one of a plurality of first application processors, where each application
processor
is one of the interactive controllers, to provide a first information service.
The
system manager also has a second service allocation server to pass
communication and control associated with a home interface controller seeking
a
second information service to an available one of a plurality of second
application
processors, each second application processor being one of the interactive
controllers, to provide the second information service; where each of the
first
and second service allocation servers operates as an independent process. The
system manager also is such that (1) the interactive controller in assigned
television communication with the calling home interface controller causes to
display on the subscriber television associated with the calling home
interface
controller a page having at least one hyperlink to an additional page and (2)
the
selection of such a hyperlink by the selection device associated with the
calling
home interface controller causes a transfer (indirect or direct hand-off)
between
one of the first and second service allocation servers to the other of them so
as to
cause a change in the information service provided to the subscriber
television.
The system manager is also such that the page and the additional page are
created in HTML format.
The interactive cable system includes (i) an information service network,
for delivering information services to subscriber televisions, (ii) a
plurality of
home interface controllers, each home interface controller associated with a
subscriber television and having a data transceiver operative over a data
communications link to the headend, (iii) a plurality of subscriber selection
devices, each such device associated with a home interface controller and in
communication with the data transceiver thereof, for permitting subscriber
interaction, and (iv) a plurality of interactive controllers, disposed at the
headend, where each interactive controller is in assignable television
communication over the network with a subscriber television and in data
communication with a subscriber selection device.
In yet another embodiment, the system manager has a first service
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allocation server to pass communication and control associated with a calling
home interface controller to one of a plurality of first application
processors,
where each application processor is one of the interactive controllers, to
provide
a first information service; a second service allocation server to pass
communication and control associated with a home interface controller seeking
a
second information service to an available one of a plurality of second
application
processors, where each second application processor is one of the interactive
controllers, to provide the second information service; wherein each of the
first
and second service allocation servers operates as an independent process; and
wherein (1) an interactive controller in assigned television communication
with
the calling home interface controller causes display on the subscriber
television
associated with the calling home interface controller of a page having at
least one
hyperlink to an additional page and (2) the selection of such a hyperlink by
the
selection device associated with the calling home interface controller causes
a
transfer (either indirect or direct hand-off) between one of the first and
second
service allocation servers to the other of them so as to cause a change in the
information service provided to such subscriber television. Further the system
manager is such that the page and the additional page are created in HTML
format.
In yet another embodiment, the system manager and cable system are such
that the cable system has (i) an information service network, for delivering
information services to subscriber televisions, (ii) a plurality of home
interface
controllers, each home interface controller associated with a subscriber
television
and having a data transceiver, operative over a data communications link to
the
headend, with a transmitter having a tunable carrier frequency; (iii) a
plurality of
subscriber selection devices, each such device associated with a home
interface
controller and in communication with the data transceiver thereof, for
permitting
subscriber interaction, and (iv) a plurality of interactive controllers,
disposed at
the headend, each interactive controller in assignable television
communication
over the network with a subscriber television and in data communication with a
subscriber selection device.
The system manager has a data path manager for maintaining a list of
available data channels for upstream communications from a calling home
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interface controller to the headend and preventing simultaneous use of a
channel
by more than one home interface controller; and an assignment system by which
the transmitter in the data transceiver of a calling home interface controller
is
caused to tune to an available channel. (A "channel" here may be a time slice,
a
frequency slice, or a code slice, although in a preferred embodiment we use a
frequency slice..) The system manager is also such that the assignment system
includes a hailing channel over which the transmitter in the data transceiver
of a
calling home interface controller seeks assignment by the data path manager of
an available channel. Further, the system manager is such that the assignment
system includes an arrangement for the periodic broadcast, from the headend
over a downstream portion of the data link to the home interface controllers,
identifying of available channels, and the home interface controller has a
rule for
picking one of the available channels for use by the transmitter in the data
transceiver of a calling home interface controller.
The servers and controllers referred to herein may be implemented as
distinct hardware elements or they may be virtual elements in one or more
computing devices.
Brief Description of the Drawings
Fig. 1 is a block diagram of a preferred embodiment of a cable television
system in accordance with the present invention, for providing information
content with interactivity;
Fig. 2 is a block diagram of an embodiment of the headend of Fig. 1,
showing the back end, front end, and switching output RF hub of Fig. 1;
Fig. 3 illustrates an embodiment of the back end of Fig. l;
Fig. 4 illustrates an embodiment of the front end of Fig. 1;
Fig. 5 illustrates an embodiment of the switching output IZF hub of Fig. 1;
Fig. 6 illustrates an embodiment of a home interface controller for use in
connection with the embodiment of Fig. 1;
Figs. 7A-7F illustrate examples of subscriber television screen displays
during an interactive session;
Fig. 8 illustrates a system diagram for the system manager of Fig. 1; and
Fig. 9 illustrates a flow diagram for a call set-up and tear down procedure
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as shown in Fig. 8.
Fig. 10 illustrates the frequency spectrum of the various signals used by a
cable television system of Fig. 1.
Fig. 11 is a high-level diagram of a home interface controller in
communication with the back end.
Fig. 12 is a high-level diagram illustrating a cable return system.
Detailed Description of Specific Embodiments
For the purposes of the description herein and the claims that follow it,
unless the context otherwise requires, the terms "cable television
environment"
and "cable television system" include all integrated systems for delivery of
any
information service to subscribers for use in connection with their
televisions.
These include conventional cable television systems utilizing coaxial cable
for
distribution primarily of broadcast and paid television programming, cable
television systems using fiber optics and mixed fiber optic-coaxial cable, as
well
as other means for distribution of information services to subscribers.
Similarly,
unless the context otherwise requires, the term "information service" includes
any service capable of being furnished to a television viewer having an
interface
permitting (but not necessarily requiring) interaction with a facility of the
cable
provider, including but not limited to an interactive information service,
video on
demand, local origination service, community event service, regular broadcast
service, etc. "Television communication" means providing an information
service
via a television information signal. A "television information signal" is any
signal
that may be utilized by a television for video display, regardless of the
form,
including a standard NTSC-modulated rf carrier, an MPEG-compressed digital
data stream, or any other format. "Interactive television service" means an
information service that utilizes an interface affording two-way communication
with a facility of the cable provider. When a node is said to be in an
"interactive
mode," it means that the node is providing an information service to the home
interface controller; the home interface controller may, but need not, be
furnishing data to the node as to what information service to provide.
Fig. 1 illustrates an embodiment of a cable television system in accordance
with a preferred embodiment of the present invention for providing information
services. The system of this figure is generally similar to that described in
United
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States patent 5,550,578, entitled "Interactive and Conventional Television
Information System", for an invention by Hoarty and Soske. The cable
television
system comprises headend 10 and distribution plant 14. Headend 10 comprises
back end 11, front end 12, and switching output RF hub 13. In back end 11,
information source 1I1 provides information source content via switch 112 to
front end 12. In front end 12, information content is switched via switch 121
to a
plurality of personal multi-media modules (PMMs) 122, usage of which is
allocated on a demand basis. Conventional cable broadcast channels 120 are
routed over main fiber trunks 144a, 144b, and 144c. Analog television
information signals from appropriate analog PMMs are processed by scrambling
at 224 and modulating at modulators 125, whereas digital television
information
signals from appropriate digital PMMs are processed by combining them into a
composite QAM (quadrature amplitude modulation) signal before going to
modulators 125. Modulators 125 and combiner 132 form part of switching output
radio frequency (RF) hub 13. The modulators are preferably capable of
modulating a carrier that is tunable by the network manager 127, so that any
given modulator may be configured to best handle demands placed on the
system.
Depending on the capacity of the cable system and the information
services sought to be delivered, some of the cable broadcast channels 120 may
be
provided over path 123 to the PMMs. Additionally, the path 123 allows the
PMMs operating interactively to permit a subscriber to make overlays on
otherwise conventional cable television programming. The output of items 125
are then combined by combiner 132 and fed to the interactive trunk 142b. The
cable distribution plant 14 includes bridger amplifiers 148, feeders 148a,
feeder
amplifiers 148b, and cable drops such as 149a, 149b, and 149c serving homes
141a,141b, and 141c.
The information services can be provided to a subscriber over virtual
channels in which the channel number changes for different interactive
information services, even though the various information services may be
provided over a fixed frequency input to the set top, with the control data
from
the subscriber's set top causing the back end to supply a different
information
service as the subscriber appears to be changing the channel.
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System manager 113 in back end 11 provides for the allocation of resources
to permit interactive services with a user, as well as procedures for call set-
up
and tear down, and is discussed in more detail in reference to Figs. 8 and 9.
Commerce manager 114 manages real-time transactions and converts billing to a
batch format for handling by legacy systems.
In Fig. 2 are illustrated back end 11, front end 12, and switching output RF
hub 13 of Fig 1. In back end 11, network interface 215 is in communication
with
an Internet service provider, return path processing telephone 212 is in
communication with telephone lines, and return path processing cable 211 is in
communication with signals provided over a cable return path. Network
interface 216, return path processing telephone 212, and return path
processing
cable 211 are also in communication with back end switches 112. Back end
switches 112 are in communication with web proxy and PMM boot and
application server 213 as well as system manager 113, and are in communication
with front end 12 via distribution switches 121. Because the PMMs in a
preferred
embodiment are diskless and lack ROM with stored software necessary for
bootup, server 213 provides booting-up for the PMMs. Also, server 213 provides
a web proxy server function so that information downloaded from a remote
server on the Internet is quickly cached on server 213.
Distribution switches 121 provide communication signals and control
signals to PMMs, which in Fig. 2 are illustrated by Internet service cards
222,
video game player cards 225, and MPEG-to-video decoder cards 227. NTSC /PAL
TV modulator cards 223, 226 and 228 provide television signals from the
outputs
of Internet service card 222, video game player card 225, and MPEG-to-video
decoder card 227, respectively, in the form of NTSC or PAL IF (intermediate
frequency) signals to switching output RF hub 13. To provide MPEG2 encoded
digital signals directly to users, MPEG2 pass-thru 229 may be implemented by
which MPEG-to-video decoder card 227 and NTSC/PAL TV modulator card 228
are bypassed; in such case 64-QAM encoding is performed before processing by
switching output RF hub 13. Within switching output RF hub 13, initial RF
processing 231 is performed in which there is one RF module per simultaneous
user, and the output of RF processing 231 is combined via switcher-combiner
132,
and final RF processing is performed by 233.
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An embodiment of back end 11 is shown in more detail in Fig. 3. Return
path processing cable 211 is provided by CDSL gateway 322 in communication
with users via RF modems 321. Return path processing telephone 212 is provided
by terminal server 314 in communication with telephone network 311 via channel
banks 312 and modem banks 313. Terminal server 314 and CDSL gateway 322 are
in communication with back end switches 112, which in Fig. 3 are indicated as
an
Ethernet switch. In the alternative presently preferred embodiment, the
terminal
server 314 and CDSL gateway 322 may be replaced by return data path switches
which distribute communications to the assigned PMMs 122 without imposing
on the back end switches 112. Network interface 216 is provided by router
firewall 332 and CSU/DSU (customer service unit/data service unit) 331. Router
firewall is in communication with ethernet switch 112. Also shown in Fig. 3
are
web proxy and PMM boot and application server 341, system manager 113,
network manager 127, and commerce manager 114 in communication with
ethernet switch 112. Also shown in Fig. 3 are operations console 351 in
communication with ethernet switch 112.
An embodiment of front end 12 is shown in Fig. 4. Ethernet switches 121
are connected to PMMs 122 through a LAN interface 412 at each PMM. A PMM
122 typically includes an SBC PC (single board computer personal computer)
card 411 for running an interactive program. A return path interface 413
receives
communications from the home interface controllers through the return path
whether it be the cable or a telephone line. A VGA to NTSC/PAL converter 414
produces a signal that can produce a picture on a television. Scrambling may
be
provided by a complete scrambler 124 assigned to the PMM or, alternatively,
scrambling may be distributed so that only one complete scrambler is required
per channel frequency. Each PMM then only needs sync suppression and a
conditional access code inserter obtaining the conditional access code from
the
complete scrambler for the respective channel frequency. An RF modulator 415
puts the NTSC or PAL signal on an intermediate frequency, preferably 45MHz,
for supply to switching output RF hub 13.
An embodiment of switching output RF hub 13 is shown in Fig. 5. Initial
RF processing is performed by 231, which are essentially integrated up-
converters, converting 45 MHZ input to an output in the range of 150 to 300
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MHZ. RF switch and combiner network 132 provides the output of 231 to final
RF processing 231, which in Fig. 5 are indicated by block channel converters
51
and amplifiers 52.
An embodiment of a home interface controller is shown in Fig. 6. A cable
149 carrying the television signals, such as drops 149a, 149b, and 149c of
Fig. 1, is
connected to a two-way splitter which may also be connected to a cable set-top
provided by a third party. A diplex filter and combiner 601 provide a first
frequency path to splitter 602 and a second frequency path to FSK (frequency
shift-key) radio 615, where the first frequency path occupies a higher
spectral
region than the second frequency path. The first frequency path provides a
downstream path for signals going from front end 12 to the user of the home
interface controller whereas the second frequency path provides an upstream
path for signals going from the user to front end 12.
Splitter 602 provides a signal path to low pass filter 606 and an impairment
removal circuit 605. The outputs of 602 and 605 are re-combined at combiner
607,
then amplified by amplifier 608. Switch 609 allows the user of the home
interface
controller to switch between the signal output of amplifier 608 and the output
of
the third party set-top 610 (if present). Switch 609 may also be under control
of
home box CPU 604.
Home box CPU 604 provides control and communication signals to
impairment removal circuit 605, duo-binary down stream radio 603, FSK
upstream radio 615, telephone interface 613, serial port 614, infrared
transmitter
612, and infrared receiver 611. Infrared transmitter 612 and infrared receiver
611
provide communication between the home interface controller and a subscriber
selection device, which may be, for example, a keyboard. Serial port 614 may
provide communication with a printer for hard copy printouts. FSK upstream
radio 615 is a modulator for providing a data communication link between the
interface controller and front end 12. Collectively, the upstream radio 615
and the
downstream rado 603 constitute the transmitter and receiver, respectively, of
a
data transceiver. Telephone interface 613 also can provide communication over
ordinary telephone lines.
When a user of the home interface controller requests an interactive
service from head end 12, such as Internet service or a video game, an
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appropriate PMM is placed in use for providing the service to the user. The
user
selects the desired service by using the subscriber selection device in
conjunction
with the home interface controller. Examples of screen displays available to
the
user for selection of a service are illustrated in Figs. 7A-7F. Fig. 7A shows
a
beginning display, in which front end 12 requests appropriate information from
the user, including a PIN code number. In this way, for example, children may
be
blocked from requesting unsuitable video content. Once the back end identifies
the user (this will be discussed in more detail later), various options are
available,
as shown in Fig. 7B. Fig. 7C shows a screen in which the "news" option of Fig.
7B
has been chosen. In Fig. 7C, once the user has decided to choose a news
program,
the user may decide to choose CNN or MSNBC. Fig. 7D shows the screen when
the user has selected the CNN option of Fig. 7C. Fig. 7E is similar to Fig.
7B,
except that this screen appears when the "Junior" button and appropriate PIN
code is entered in Fig. 7A. Fig. 7E shows the screen that results when the
"games" button in Fig. 7E is entered. It should be noted that the interaction
here
is via an Internet-type browser, which permits not merely surfing the
Internet,
but actually selecting different information services using hyperlinks.
Fig. 8 illustrates a system diagram for system manager 113, indicating the
two functions of (1) call set-up and tear down and (2) resource allocation
with the
interactive TV system of Fig. 1. Call set-up is the process of causing the
assignment of a television information signal path to the home interface
controller for interactive service, and resource allocation is the process of
assigning appropriate PMM cards and virtual circuits within the switching
system in the back end.
Call set-up is initiated by a small program in the home interface controller
which keeps track of the channel the user is watching. The channels are broken
into bands where, for instance, channels 2 through 73 are assigned regular TV
programming both off-air TV channels as well as cable channels such as MTV,
HBO, CNN, etc. The band above this broadcast band uses channels 74 to 79, for
instance, for interactive services where a user is assigned one of these
channels
only during the duration of that user's interaction with the interactive TV
system
(i.e. - while looking up a restaurant in the entertainment guide, or while
watching
a movie, etc.). A user may tune from a broadcast channel (e.g. - ch. 37 CNN)
to
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an interactive service virtual channel, at which time the user will be
provided
with the screen displays of the type shown, for example, in Figs. 7A through
7F.
When the user selects interactive service, the small program in the home
interface
controller sends a signal to the system manager at the back end to initiate
call set-
up.
The system manager in back end 11 begins the call set-up process through
a system manager subsystem called the call setup server (CSS) 80. The CSS 80
finds a free interactive element or selection element corresponding to the
virtual
channel number the user is trying to tune to. As an example, assume the user
is
interested in movie previews which are viewed through interacting with a PMM
and a program run on service "A" application process 811. The CSS 80 will call
a
video path manager subroutine to check for an available television information
channel within the band of television information signals allocated to provide
interactive service to the neighborhood of the requesting user. The newly
assigned television information signal of the requesting user and the user's
network address is passed to a service allocation server (SAS) 81 associated
with
the application process.
Assuming a non-blocked call, the system management function has now
passed from the CSS 80 sub-system to the SAS 81 (for this example). The CSS 80
is now out of the loop. The SAS 81 checks for a free resource, i.e., a
processor for
running a service application process. if one is available, control is passed
to it
along with the assigned television information signal and address of the
calling
user. The processor, in this example, is a PMM card 122. The service
application
process run by the PMM sends a request to the application support server 87
for
subscriber information to authenticate the user id for the neighborhood from
which the signal is originating. The service application process also requests
subscriber information from the application support server 87 customer
database
to check for paid-up service and/or access to service permission (e.g. - used
to
block children from viewing R rated movie previews, for one example). Upon
success, the service application process directs the conditional access
controller
(CAC) 86 to send a descramble key code to the user's set-top converter to
allow it
to descramble the video signal that the service application process will be
using.
The service application process also communicates directly with the set-top in-
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home operations process (IHOP) 85, informing the program of the assigned
television information signal. The home interface controller operates the in-
home
operations process. A separate processor in the set-top receives the
descrambling
keys and translates them.
The set-top IHOP 85, upon receiving the assigned channel, tunes the cable
TV set-top to the assigned channel. The user will see the output of the SAP
811
and can begin using the remote control to manipulate the program running on
the SAP 811. The in-home operation process 85 transmits appropriate remote
control commands addressed to the processor/process assigned to it. When the
user tunes to a broadcast TV channel, the call take down process is initiated
by
the set-top system manager extension signaling the 811 that the user has tuned
away, and, after a time-out period (for instance, five minutes), the 811
signals the
call set-up server 80 to release the interactive virtual channel previously
assigned.
The virtual channel is logged back into the free channels list by the CSS 80.
At
the same time, the SAP 8I1 signals the SAS 81 that it is now a free resource
and
the SAS places the PMM that had provided the application process on its free
card list.
The example above is the same for other kinds of PMMs for interactive
multimedia, such as Internet service cards 222, video game player cards 225,
and
MPEG-to-video decoder cards 227. A PMM card can be used for a front end
application such as movie previewing and purchasing. When the user picks a
movie using a PMM, the PMM will then pass control of the user to a control
program that manages movie playback and decompression (MPEG2 to NTSC).
When the movie is over, the movie playback control program follows the same
steps of call take down as the PMM did.
The above system management scheme can accommodate any number of
diverse services in a fully distributed manner such that there are no
bottlenecks
in the system. This affords optimal performance in response to user requests.
By
distributing the processing of communications with home interface controllers
throughout system management, a greater amount of processing can be
conducted in less time with less expensive processing units.
System management may include separate service allocation servers 81 or
82 for each of the switched channel system, the digital interactive elements,
and
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the analog interactive elements. Moreover, there may be additional service
allocation servers further dividing the interactive elements into groups
according
to the type of interactive service provided. Thus, there may be a service
allocation server for movies only, for games, and for catalogs. The service
allocation servers act as intermediaries between the call set-up server and
the
video provider elements whether they be Internet service cards 222, video game
player cards 225, or MPEG-to-video decoder cards 227. The service allocation
servers provide distributed management. The call set-up server 80 can pass the
call set-up to the appropriate service allocation server. As the service
allocation
server identifies a video provider element and completes the connection with
the
home interface controller, the call set up server can be attending to the next
caller.
As mentioned above, the user interface may be provided with hyperlinks
which when activated permit selection of different information services. For
example, a user interacting with a catalog may find a hyperlink to a movie,
which
when selected puts the user in connection with a movie service. The hyperlink
institutes a routine which causes a hand-off from the service allocation
server
handling catalogs to the service allocation server handling movies. Such a
routine may begin by having the currently assigned service allocation server
ask
the target service allocation server if it can accept a new user. If not, the
user may
need to wait before the hyperlink can be completed. If available, the current
service allocation server passes user identification information to the target
service allocation server and terminates the current session freeing up the
current
service application process. The target service allocation server assigns a
processor to the user for running a service application process (to play a
movie in
the example). If a channel change is necessitated, the video path manager is
involved and the home interface controller of the user is informed of the new
channel. Communication proceeds between the home interface controller and
the newly assigned service application process.
The communications gateway 83 acts as a translator between the IHOP 85
and the back end 11 LAN connecting the distributed processes of the system
manager. The communications gateway 83 translates the IHOP address from an
individual user into a global Internet Protocol (IP) address for addressing
ethernet data packets within the back end LAN. IP is part of TCP/IP.
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Communications are directed from the communications gateway 83 to the
application process directly. Once the service allocation server assigned to a
home interface controller has put the home interface controller in
communication
with the requested application process, the communications can be handled
directly. The control of the switched channel system is simple in that it is
only
necessary to put the requested information service on the assigned television
information signal. The interactive elements require greater processing
requirements as interactive communications continue throughout a session.
System management is also required to maintain administrative tasks such as
billing. Each of the service application processes is in communication with a
transaction interface process so that billing and credit and other financial
matters
can be taken care of.
Fig. 9 illustrates a flow diagram for a call set-up and tear down procedure
as shown in Fig. 8. In Fig. 9, step 91 indicates that a request for an
interactive
service from a home interface controller is made on a hailing frequency. The
hailing frequency need only occupy a relatively small bandwidth at a
relatively
low carrier frequency (compared to ordinary television signals). In step 92,
the
gateway receives the request from the user and transmits a private frequency
(approximately 25 kHz bandwidth) assignment to the home interface controller
to be used for upstream data. In step 93, the gateway also converts the
private
address to an IP address, as discussed in relation to Fig. 8. In step 95, the
system
manager hands off to the call set-up server, and in step 951, the call set-up
server
hands off to the service A (for example) allocation server. In step 952, the
service
allocation server hands off to the video path manager to identify an open TV
channel to assign to the home interface controller. In step 953, the video
path
manager hands off to service A application process to identify an available
PMM
to run service process A and to assign to the home interface controller
requesting
the requested service. In step 954, the assigned PMM provides an interactive
menu and, if selected, Internet Web service is provided via an application
support server (proxy server). Step 96 indicates that a newly requested
service is
handled by service A allocation server. If a new service is requested, then in
step
97 the service A allocation server hands off to the call set-up server, and in
step
98 the call set-up server hands off to the appropriate service allocation
server.
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Step 99 indicates that additional processing maybe necessary, depending upon
the requested service (as discussed in relation to Fig. 8). Application
processing is
terminated in step 991 when the interactive service is completed, whereupon in
step 992 the assigned TV channel is returned to the pool of available channels
to
the video path manager. Also, upon completion of the interactive service, the
assigned PMM is also made available to the pool of available service
application
processors. In step 994, the assigned frequency is returned to the pool of
available
frequency assignments so that the gateway can re-use the frequency for
upstream
data from another home interface controller.
Fig. 10 indicates the frequency spectrum of the various signals used by the
television system. The spectrum to the left of the left-to-right arrow in Fig.
10
indicates upstream data, whereas the spectrum to the right of the right-to-
left
arrow in Fig. 10 indicates downstream data. Interactive channels (NTSC video
or
MPEG2) are in channels 74-79 (522 MHZ to 552 MHZ). Upstream data has a small
bandwidth of 25 kHz in the frequency range of 5 MHZ to 40 MHZ.
Fig. 11 shows a high-level diagram of the home interface controller in
communication with the back end. In this embodiment, downstream data is in
the form of packet data on a 300 Kbps data channel. When providing upstream
data, the home interface controller uses a dedicated upstream channel
requiring
only a 25 kHz bandwidth for each home interface controller, so as to provide
noise immunity. Fig. 11 is similar to Fig. 10, except that a common upstream
channel is used by all the home interface controllers for hailing the back
end. No
carrier or collision detection algorithms are employed, but rather, any lost
requests due to collisions among the home interface controllers are "detected"
by
an absence of response from the back end after a suitable time-out. This
common
upstream channel is used only briefly during and initial log-on to request a
private data channel, where the private data channel is indicated in Fig. 12.
As an
alternative to the use of a hailing channel, the system manager may include an
arrangement for the periodic broadcast, from the headend over a downstream
portion of the data link to the home interface controllers, identifying of
available
channels; in this embodiment, each home interface controller has a rule for
picking one of the available channels for use by the transmitter of its data
transceiver.
