Title: Session oriented settop communication using dynamic, synchronized routing
Abstract: A system which provides session oriented communications between a settop terminal and a headend of a CATV communication system assigns downstream and upstream communication paths to the communication. A data router monitors the downstream communication path and re-routes the downstream communication path when a channel change is requested by a subscriber. The settop terminal notifies the data router that a channel change has been requested by the subscriber. The router re-routes the downstream portion of the data communication to the new channel requested by the subscriber, thereby insuring an uninterrupted data communication session.
Patent Number: 6,918,135 Issued on 07/12/2005 to Goffin, II
| Inventors:
|
Goffin, II; Glen Peter (Fountainville, PA)
|
| Assignee:
|
General Instrument Corporation (Horsham, PA)
|
| Appl. No.:
|
265774 |
| Filed:
|
March 10, 1999 |
| Current U.S. Class: |
725/116; 725/34 |
| Intern'l Class: |
H04N 007/02.5; H04N007/10; H04N007/17.3 |
| Field of Search: |
725/32- 36,91,93,94,114,116,117,131
348/180,192,461,465,473,474,705
|
References Cited [Referenced By]
U.S. Patent Documents
| 5734833 | Mar., 1998 | Chiu et al.
| |
| 5999970 | Dec., 1999 | Krisbergh et al.
| |
| 6124878 | Sep., 2000 | Adams et al.
| |
| 6201538 | Mar., 2001 | Wugofski.
| |
| 6304578 | Oct., 2001 | Fluss.
| |
| 6484318 | Nov., 2002 | Shioda et al.
| |
| 6574797 | Jun., 2003 | Naegeli et al.
| |
| Foreign Patent Documents |
| 9414279 | Jun., 1994 | WO.
| |
| 9641478 | Dec., 1996 | WO.
| |
| 9716925 | May., 1997 | WO.
| |
Primary Examiner: Grant; Chris
Assistant Examiner: Lonsberry; Hunter
Attorney, Agent or Firm: Volpe and Koenig, P.C.
Claims
1. A headend for transmitting downstream a CATV signal having a plurality of
program channels and for facilitating bidirectional data communications with CATV
settop terminals which receive said program channels over a CATV network; said
headend comprising:
a processing means associated with each of the program channels for selectively
inserting communication data into the associated program channel for downstream
transmission; and
means for bidirectional communication with settop terminals of upstream and associated
downstream communication data including:
means for receiving upstream communication data from said settop terminals including
settop terminal identification information and current settop terminal channel
selection information; and
a data router, responsive to said current settop terminal channel selection information,
for directing downstream communication data associated with the upstream communication
data from an identified settop terminal to the processing means associated with
the channel corresponding to the current settop terminal channel selection information
of the identified settop terminal, whereby a user continues to receive the same
downstream communication data through the new program channel that the user has
selected.
2. The headend of claim 1 further including a storage means for storing said
settop terminal identification information and for storing said current settop
terminal channel selection information.
3. The headend of claim 1 wherein said data router is coupled to a telecommunications
network for transmitting and receiving data communications between said telecommunications
network and said CATV network.
4. The headend of claim 1 wherein each processing means further includes means
for combining a plurality of program channels to create a program channel multiplex.
5. The headend of claim 4 wherein each of said processing means inserts the downstream
data communication into said program channel multiplex to provide a baseband multiplex.
6. The headend of claim 5 wherein each of said processing means further includes
means for upconverting said baseband multiplex to a desired carrier frequency for
transmission to the settop terminals.
7. A method for providing bidirectional data communications over a CATV network
having a headend and at least one settop terminal, the method comprising:
(a) generating a plurality of program channels at said headend with a plurality
of program channel processing means;
(b) transmitting said plurality of program channels from said headend to said
settop terminal;
(c) receiving said plurality of program channels at said settop terminal;
(d) selecting, at said settop terminal, one of said plurality of program channels;
(e) monitoring said settop terminal from said headend and determining said selected
program channel;
(f) routing a downstream data communication to the program channel processing
means which generates said selected program channel, whereby a user can change
the selected program channel and continue to receive the same downstream data communication
through the new program channel that the user has selected; and
(g) receiving an upstream data communication from said settop terminal.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to cable television (CATV) networks and services. More
particularly, the invention relates to an in-band traffic routing system for a
CATV communication system.
2. Description of the Related Art
CATV network operators have begun to offer their subscribers an increasingly
diverse array of services from which to choose. In addition to the more "traditional"
services that are offered, such as broadcast and premium video entertainment services,
settop terminals are capable of handling interactive data and services.
The CATV transmission spectrum
21, as shown in FIG. 1, typically extends
up to one gigahertz (1 GHz). In order to provide a bidirectional communication
flow over the cable transmission network between the headend and the settop terminals,
the transmission spectrum
21 is divided into upstream and downstream bandwidths
26,
28. The upstream bandwidth
26 is utilized to send communications
from a settop terminal to the headend. The downstream bandwidth
28 is for
communications from the headend to the settop terminals. The upstream bandwidth
26 includes frequencies from five to fifty megahertz, and typically includes
a plurality of upstream communication channels
37. The downstream bandwidth
28 includes frequencies above fifty megahertz, and is further divided into
a plurality of "in-band" channels
32, each having a bandwidth of 6 MHZ.
The in-band channels
32 are primarily used for transmission of analog or
digital video broadcasts and their associated analog or digital audio programs.
Data channels
33, which typically have a much smaller bandwidth than in-band
channels
32, are interspersed throughout the upstream bandwidth
26
and are used to transmit all other downstream communications. A separate control
data channel (CDC)
34 is provided as a fixed data channel for facilitating
administrative functions.
When an interactive communication is desired by the user of a settop terminal,
the downstream communication path is established on one of the downstream data
channels
33,
34. The upstream communication path is established on
one of the upstream communication channels
37 or via the local telecommunication
(telco) network. The drawback with this type of arrangement is that a settop terminal
must have two separate receivers: 1) a tuner for receiving the in-band channels
32; and 2) an out-of-band data receiver for receiving the data channels
33,
34. This increases the cost and complexity of the settop terminal.
One alternative for eliminating the need for a separate data receiver is to send
the data within the in-band channels
32. However, a significant problem
in establishing communications between a headend and a settop terminal in this
manner is that the downstream communication path is almost randomly dynamic. Since
the downstream communication path is dependent upon the in-band channel
32
that a subscriber selects, it is impossible to predict when a change to a different
in-band channel
32 will be made, or to which in-band channel
32 the
tuner will be tuned. If a communication session using an in-band channel
32
is initially established, the subscriber must not change in-band channels
32
during the duration of the session or the downstream communication path will be
lost, thereby interrupting the session. This is unacceptable for data-critical applications.
An alternative for eliminating the data receiver is to replicate the out-of-band
data stream on each in-band channel
32. In this manner, the out-of-band
data stream is available for every in-band channel
32 that the subscriber
chooses. However, this approach is inherently wasteful of the bandwidth if the
data is only required for a single settop terminal, such as for an interactive communication.
Accordingly, there exists a need for a system which conservatively utilizes
the available communication bandwidth and does not require two separate receivers.
SUMMARY OF THE INVENTION
The present invention is a system which provides real-time session oriented communications
between a settop terminal and a headend. The system in it initially assigns both
downstream and upstream communication paths. The system monitors the downstream
communication path associated with the session and re-routes the downstream communication
path when a channel change is requested by a subscriber. The settop terminal notifies
a data router within the headend that a channel change has been requested by the
subscriber. The data router re-routes the downstream communication path from the
current in-band channel to the next in-band channel, thereby insuring an uninterrupted
communication session. In this manner the data can "follow" the settop terminal
as the subscriber changes in-band channels. Accordingly, it becomes unnecessary
to replicate the data on more than one in-band channel.
Accordingly, it is an object of the present invention to provide a system
which efficiently utilizes the transmission spectrum of a CATV communication system
by providing data communications within in-band channels.
Other objects and advantages of the present invention will become apparent
after reading the description of a presently preferred embodiment.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is the transmission spectrum utilized by a CATV communication system.
FIG. 2 is a simplified view of a CATV communication system.
FIG. 3 is a block diagram of a headend made in accordance with the present invention.
FIG. 4 is a block diagram of a settop terminal made in accordance with the present invention.
FIG. 5 is a more detailed block diagram of a headend including the data module
in accordance with the present invention.
FIG. 6 is a look-up table implemented in memory.
FIG. 7A is a flow diagram illustrating the data re-routing process in accordance
with the present invention.
FIG. 7B is an alternative embodiment of the data re-routing process in FIG. 7A.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The preferred embodiment is described with reference to the drawing figures where
like numerals represent like elements throughout.
A CATV communication network
10 embodying the present invention is shown
in FIG.
2. The communication network
10 generally comprises one or
more uplinks
14 which communicate with a plurality of headends
16,
each of which in turn communicates with a plurality of settop terminals
12.
The settop terminals
12 receive transmissions from the headend
16
through the CATV network
22. The network
22 may comprise a standard
coaxial network, a hybrid fiber-coax network or a "wireless cable" network comprising
microwave antennas and receivers. The settop terminals
12 are the user interface
between a subscriber, the subscriber's receiving and transmitting equipment, (such
as a television, a stereo system, a PC or other devices), and the communication
network
10.
The uplink
14 is located remotely from headends
16 and communicates
with the headends
16 via a satellite link
20. The uplink
14
generally receives video, audio and data content from remote content providers
70, (shown in FIG.
3), and forwards the content to the headends
16.
This content may originate in digital or analog form and may include live or archival
programs or interactive services, (for example movies, electronic encyclopedias,
electronic catalogs and downloadable applications) The content is transmitted to
the uplink
14 from a plurality of separate remote content providers
70
and is combined at the uplink
14 before being forwarded to the headends
16. Alternatively, a plurality of uplinks
14 may independently provide
the content to each headend
16 which will receive and coordinate the transmissions
from the uplinks
14.
The content from separate uplinks
14 and direct transmissions from remote
content providers
70 are received and multiplexed together at the headend
16 and forwarded to the settop terminal
12 via a plurality of in-band
channels
32. The programs on a given in-band channel
32 may comprise
analog video and audio, digital video and audio, digital data or any combination
or multiplex thereof. Thus, ten separate programs or more may be multiplexed within
a single in-band channel
32. When a subscriber selects a program for viewing
and/or listening, the settop terminal
12 will tune to the corresponding
in-band channel
32 and will access the desired program from among the plurality
of programs within the multiplex on that in-band channel
32.
Referring to FIG. 3, a headend
16 made in accordance with the teachings
of the present invention is shown. The headend
16 receives the content from
remote content providers
70 directly, or via an uplink
14, and retransmits
this information over the CATV transmission network
22 in a manner that
is well known to those skilled in the art. The headend
16 may also be the
origination source of local programing content. Optionally, the headend
16
may be coupled with a local telecommunication (telco) network
71.
The headend
16 includes a controller
60 which controls all internal
functions of the headend
16 including the reception and transmission of
video, audio and data content to and from the remote content providers
70
and the settop terminals
12. The headend
16 also includes a video/audio
programming module
66 and a data module
64. The video/audio programming
module
66 facilitates transmission and reception of video and audio content
between the remote content providers
70 and the settop terminals
12
as is well understood by those of skill in the art. The data module
64 facilitates
data communications between the headend
16 and settop terminals
12;
whether those communications originate via one of the settop terminals
12
or by an entity located outside of the CATV communication network
10. The
manner in which these data communications are processed by the data module
64
will be described in greater detail hereinafter.
Referring to FIG. 4, a block diagram of a settop terminal
12 made
in accordance with the present invention is shown. The settop terminal
12
includes a frequency agile tuner
110, a data transmitter
142, a microprocessor
111, (including an associated memory, not shown), and an IR receiver
148.
The tuner
110 receives all video, audio and data communications from the
headend
16. The data transmitter
142 transmits data from the settop
terminal
12 to the headend
16.
The microprocessor
111 controls all internal functions of the settop terminal
12, including the processing of video and audio content for output to a
subscriber's television
114, in a manner that is well understood by those
of skill in the art. The microprocessor
111 facilitates the reception of
data from the headend
16 via the tuner
110 and the transmission of
data to the headend
16 via the data transmitter
142. The microprocessor
111 also facilitates communication with an external data device
113,
such as a keyboard, a PC, or a joystick, via a data input/output (I/O) port
115.
The settop terminal
12 receives channel change and volume control instructions
from the subscriber via a remote control
144. The remote control
144
includes an infrared (IR) signal emitter
146 which sends IR control signals
to the IR receiver
148. The settop terminal
12 may also receive control
instructions from an external data device
113 via the external data input/output
(I/O)
115 or a front panel keyboard (not shown).
Video, audio and data content from the headend
16 is transmitted across
the CATV network
22 and is processed through the tuner
110 and the
microprocessor
111. The tuner
110 is responsive to tune to the frequency
of the in-band channel
32 selected by the subscriber. It should be noted
that since the content transmitted on an in-band channel
32 may comprise
a multiplex of separate video, audio or data programs, the microprocessor
111
must translate the "channel" selection input by the subscriber into the correct
in-band channel
32 and the correct program within the multiplex. The microprocessor
111 accesses the program from the multiplex and descrambles the selected
baseband signal. Digital video and audio is decrypted, decoded and D/A converted.
The baseband video and audio signal is placed on a second carrier signal frequency,
typically television channel 3 or 4, for output to the television
114. Data
content is forwarded by the microprocessor
111 to the proper destination.
For example, the data content may comprise electronic programming guide (EPG) information
which will be stored within the settop terminal
12 until the EPG is utilized
by the subscriber. The data content may alternatively be forwarded through the
data I/O
115 to the subscriber's PC
113.
Referring to FIG. 5, a detailed block diagram of a headend
16 including
a data module
64 is shown. The data module
64 includes a data router
202, a modulator
204 (optional) and a demodulator
206. The
data router
202 is coupled to the controller
60, the telco network
71, and the video/audio programming module
66. The video/audio programming
module
66 includes a processing means
201-
207 for each in-band
channel
32, (shown in FIG. 5 as Channel
1 . . . Channel N). Each
processing means
201,
203,
205,
207 comprises a receiver/multiplexer
(R/M) module
210,
212,
214,
216, and an up-converter
220-
226. All of the up-converters
220,
222,
224,
226 are coupled to a combiner
230.
The video, audio and data content from the uplinks
14 and content providers
70 is forwarded to the video/audio programming module
66. The programming
module
66 creates a plurality of content multiplexes
209,
211,
213,
215; one for each in-band channel
32. Each content multiplex
209,
211,
213,
215 is forwarded to a respective R/M
module
210,
212,
214,
216. Each R/M module
210,
212,
214,
216 further multiplexes any data forwarded from
the data router
202 with the respective content multiplex
209,
211,
213,
215 to create an baseband multiplex
217,
219,
221,
223. Each baseband multiplex
217,
219,
221,
223 is then forwarded to the corresponding up-converter
220,
222,
224,
226 which places the baseband multiplexes on the proper carrier
signals within the transmission spectrum
21 for transmission. The combiner
230 combines the signals from all of the up-converters
220,
222,
224,
226 for transmission through the CATV plant
22 to the
settop terminals
12. If a data-only transmission is desired, it may be forwarded
by the data router
202 through the modulator
204 on a data channel
33 (as shown in FIG.
1). The data channel
33 is then sent
to the combiner
230 for combining with all other channels. Use of the data
channel
33 would necessitate the use of a data receiver at the settop terminals
12 to receive the data.
The upstream path is from the settop terminals
12, through the CATV plant
22, into the headend
16 terminating at the demodulator
206.
For upstream communications, the microprocessor
111 within the settop terminal
12 forwards the baseband communication to the data transmitter
142
which upconverts the communication for transmission on one of the upstream data
channels
37. The data transmitter
142 may share an upstream channel
37 with a plurality of other settop terminals
12. Alternatively,
the data transmitter
142 may be frequency agile and may search for the next
available upstream channel
37 or request the next available upstream channel
37 from the data router
202 within the headend
16. Any one
of a plurality of known methods may be used to transmit this information upstream
since the particular method of transmission of signals from the settop terminal
12 to the headend
16 is not central to the present invention. Preferably,
the upstream communication will include a header which identifies the settop terminal
12 from which the upstream communication emanated.
The data router
202 stores information pertinent to each settop terminal
12; such as the address of each settop terminal
12 the in-band channel
32 to which each settop terminal
12 is tuned, and the upstream channel
37 requested by the settop terminal
12. This information may be periodically
transmitted to the data router
202 by each settop terminal
12, or
may only be transmitted upon initial settop terminal
12 energization and
upon a channel change. As shown in FIG. 6, this may be stored in memory
290
within the data router
202 or the controller
60 as a look-up table
291. For example, the look-up table
291 indicates that subscriber
number 129 is currently tuned to channel 50. Accordingly, data intended for subscriber
number 129 is forwarded by the data router
202 to the R/M module
210,
212,
214,
216 that corresponds to in-band channel 50 and will
transmit on upstream channel J. The data is multiplexed with the content multiplex
for that channel to form the baseband multiplex
217-
223 for transmission
to the settop terminal
12. Data is received from subscriber number
129
on upstream channel J.
Referring back to FIG. 5, the return path demodulator
206 receives
signals sent from the settop terminals
12 and demodulates the signals. The
demodulated signals are forwarded to the data router
202, which reads the
signals' destination address, comprising a settop terminal address, URL web address
or any other form of electronic address, and determines where the signal must be
routed. For example, the data router
202 may broadcast the signal to all
settop terminals
12, forward the signal to a particular settop terminal
12, or transmit the signal to an external entity, such as a website, via
the telco network
71. Signals forwarded to a particular settop terminal
12 are routed to the R/M module
210,
212,
214,
216
which generates the in-band channel
32 to which the particular settop terminal
12 is tuned. The settop terminal
12 receives the data over that in-band
channel
32. Alternatively, the data router
202 may forward a communication
to a settop terminal
12 via the optional modulator
204.
In order for the communication session to continue to completion without interruption,
the data router
202 must always know the in-band channel
32 to which
the settop terminal
12 is tuned. Accordingly, the settop terminal
12
forwards a "channel change notification" to the data router
202 when a subscriber
desires to tune the settop terminal
12 to a new in-band channel
32.
This channel change notification comprises the address of the settop terminal
12,
(or a similar identification number), and the new channel number. The new channel
number is derived from the preceding or subsequent channel when the down (▾)
or up (▴) channel keys on the remote control
144, respectively, are
depressed; or it is derived from the channel number input directly by the subscriber.
The data router
202 detects the channel change notification, updates the
look-up table
291 and routes all subsequent data for that settop terminal
12 to the R/M
210,
212,
214,
216 corresponding
to the new in-band channel
32. Additionally, if there is a conflict resulting
from two subscribers that attempt to use the same upstream communication channel
37, the data router
202 detects the conflict and notifies one or
both of the subscribers to relocate to a different channel.
In an alternative embodiment, the settop terminal
12 will not change from
the current in-band channel
32 to a new in-band channel
32 until
all of the data on the current in-band channel
32 has been safely delivered
to the settop terminal
12 and the data router
202 has forwarded a
"channel change confirmation" message to the settop terminal
12. Data transmissions
will be temporarily halted or stored in memory
290 until the settop terminal
12 receives the channel change confirmation message and confirms that it
has tuned to the new in-band channel
32. This confirmation is communicated
to the data router
202 via a "new channel confirmation" message transmitted
from the settop terminal
12 to the data router
202.
Referring to FIG. 7A, a flow diagram illustrating the data re-routing process
in accordance with the present invention is shown. In order to change channels
and continue to receive uninterrupted data flow, a subscriber initiates a channel
change (step
602) and the settop terminal
12 forwards a channel change
notification to the data router
202 (step
604). After a predetermined
delay, which may be on the order of milliseconds, the settop terminal
12
changes to the new in-band channel (step
612). This delay permits the settop
terminal
12 to receive any data that was sent by the data router
202
prior to the receipt of the channel change notification by the data router
202.
The data router
202 detects the channel change notification (step
606),
updates the lookup table
291 (step
608) and routes all subsequent
data to the respective R/M module
210,
212,
214,
216
(step
610) for the new in-band channel. In order to avoid the loss of data
during a channel change, the data may be transmitted simultaneously on the old
channel and the new channel for a predetermined duration, or may briefly be stored
within memory
290.
Referring to FIG. 7B, a flow diagram illustrating an alternative method
in accordance with the present invention will be described. In this method, steps
702-
708 are the same as corresponding steps
602-
608.
However, several additional steps are performed in order to confirm that data is
being properly routed. Referring to step
710, the data router
202
prepares to send all subsequent data to the respective R/M module
210,
212,
214,
216 for the new in-band channel; however, it does not send the
data until steps
712 through
718 have been completed. In essence,
the data transmission will be suspended until the new channel has been acquired
and a confirmation is sent to the data router
202.
Referring to step
712, the data router
202 forwards a "channel
change confirmation" to the settop terminal
12. The settop terminal
12
receives the channel change confirmation (step
714) and changes to the new
in-band channel (step
716). The settop terminal
12 then confirms
that it has tuned to the new channel by transmitting a "new channel confirmation"
message to the data router
202 (step
718). After the data router
has received the new channel confirmation message, all subsequent data communications
are then routed by the data router
202 to the new respective R/M module
210,
212,
214,
216 associated with the in-band channel.
*
