GB2422754A

GB2422754A - Digital multicast system

Info

Publication number: GB2422754A
Application number: GB0501546A
Authority: GB
Inventors: Wai Kin Lee
Original assignee: PCCW HKT Datacom Services Ltd
Current assignee: PCCW HKT Datacom Services Ltd
Priority date: 2005-01-27
Filing date: 2005-01-27
Publication date: 2006-08-02
Anticipated expiration: 2025-01-27
Also published as: GB2422754B; HK1089012A1; GB0501546D0

Abstract

A digital multicast system for distributing channels of multimedia programmes to subscriber locations (900) over a digital network. The system has a digital subscriber line access multiplexer or DSLAM (400) for receiving the channels, and telephone lines (330) for transmitting them to the locations (900). The DSLAM (400) has a conditional access unit or CAU (410) which includes a data memory for storing a customer profile for each subscriber including subscribed channels and permits or denies access to the channels based on the customer profile. The CAU (410) identifies a "Preview" state for an unsubscribed channel for a subscriber and permits limited access to that channel for temporary viewing, and/or a "Private" state for a certain channel for access by subscribers nominated by a content provider of that channel.

Description

DIGITAL MtJLTICAST SYSTEI'! The present invention refers to improvements

relating to digital video and audio multicast services that are used to distribute television and video programmes, etc. from a single source or head End' simultaneously to many locations over a digital network including subscriber lines.

SU*RY OF THE INVENTION According to the invention, there is provided a digital multicast system for distributing channels of multimedia programmes from a programme source to a plurality of subscriber locations over a digital network, comprising a digital subscriber line access multiplexer connected by the network to the programme source for receiving the programme channels, and a plurality of data lines connected from the multiplexer to the locations for transmitting the programme channels thereto. Included is a conditional access unit associated with the multiplexer and including a data memory for storing a customer profile for each subscriber including channels subscribed thereby. The conditional access unit is adapted to permit or deny access to the programme channels by each

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o i * i I * .0 * I. lIE * I I * 0 I I I I III It I subscriber based on the corresponding customer profile.

There is also a digital decoder provided at each the location and connected to the corresponding data line for processing incoming programme signals and accessing the corresponding customer profile. The conditional access unit is adapted to identify a preview state for an unsubscribed channel for a subscriber and to permit limited access to the channel by the subscriber for temporary viewing thereof.

Preferably, the limited access to the channel is limited to a predetermined interval of time.

More preferably, the limited access to the channel is repeatable for a predetermined number of times over a predetermined period of time.

More preferably, the limited access to the channel is not repeatable for a predetermined period of time following the access.

It is preferred that the preview state is included in the tomer profile for the subscriber.

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I. S I * * I I IS * S * I I S S * S. * S S S S S S * II* S. -3.- In a preferred embodiment, the digital multicast system includes a multicast video portal connected by the network to the conditional access unit to enable on-line updating of the customer profiles by the subscribers, the multicast video portal being accessible by the subscriber using the corresponding digital decoder via the multiplexer to subscribe to the channel.

More preferably, the digital decoder includes browser means to promote subscription to the channel.

More preferably, the multicast video portal includes a database including a master copy of the customer profiles, based on which the customer profiles in the conditional access unit are to be updated.

It is preferred that the conditional access unit is adapted to identify a private state for a specific channel for access by subscribers predetermined by a content provider of the channel.

BRIEF DESCRIPTION OF DRAWING

The invention will now be more particularly described, by way of example only, with reference to the accompanying * * : .. .11 * * * ** S *,. S S * S S S * e S drawing, which is a schematic block diagram of an embodiment of a digital mu].ticast system in accordance with the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Referring to the drawing, there is shown a digital multicast system embodying the invention for distributing a large number of multimedia programmes, especially video programmes, from a single head end source 200 to many subscriber locations 900 over a digital network 300, as a payTV service. The subscriber locations 900 are mostly but not exclusively home locations including those as depicted in a residential building. The digital network 300 is shared by other telecommunication services and, for these purposes, includes the Internet 310, an IP (Internet Protocol) network 320 connected to the Internet 310, and domestic telephone lines 330 leading to respective subscriber locations 900.

The digital multicast system incorporates a Multicast Video Portal or MVP 100 for operation. The I? network 320 may be divided into an I? multicast network 322 and an IP core network 324. The MVP 100 and the head end source 200 are set up in a place remote from the subscriber * * . I * : : * * * * I. I.. I I I I

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*:. *. * locations 900, for example at the site of the system operator. The MVP 100 is connected to the IP core network 324, and the head end source 200 to the IP multicast network 322.

As is typical for digital mu].ticast services, multiple video and audio signals are encoded in a compressed format such as MPEG2 or MPEG4 at the head end source 200 and then transmitted in an IP packet format over the IP network 320 and more specifically the IP multicast network 322. These many xnulticast signals are received at a Digital Subscriber Line Access Multiplexer or DSLAN 400 which is usually located at the subscribers' building or a telephone exchange for that area. The DSLN4 400 is connected typically by optical fibre to the IP network 320 and more specifically the IP core network 324 and to a Public Switched Telephone Network or PSTN 340.

The IDSLAM 400 transmits and receives digital signals over a copper pair circuit or telephone line 330 connecting to each subscriber location, serving up to 192 subscribers for example. The copper pair circuit 330 also carries conventional telephone service such that both the telephone and the broadband IP signals can be used simultaneously.

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* . S I S S * * The maximum bandwidth of the digital signals will be limited by the length of the copper pair circuit 330, but will typically be up to 6Mbps downstream (from the DSLAM 400 to the customers) for lines up to 2km in length, with a lower capacity upstream from the customers to the DSLM 400. This capacity is sufficient to carry a high quality digital MPEG2 video signal, as well as allowing Internet access and telephony on the same line. If the DSLM 400 is located in or near the customers' building, the bandwidth can be increased to over 20Mbps downstream, allowing the simultaneous transmission of more than one MPEG2 or MPEG4 signal to the home or office over a single copper pair circuit 330.

At each subscriber location 900, normally connected to the incoming telephone line 330 are a telephone set 331 for telephone service and a modem 332 for signal decoding and encoding to enable Internet access via a personal computer 333. Also connected to the modem 332 is a digital decoder 334 which converts the incoming EG digital signals into conventional video and audio normally analoua, for a TV t 336 conneoted thereto. a.

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I.e I. Each copper pair line 330 carries one channel of video/audio programme signals, and the digital decoder 334 is provided with a remote control unit 335 that allows the user to select one from the many channels available at the DSLAN 400. In this way, the subscriber can gain access to a relatively unlimited number of channels, in contrast to the limited number available in the existing cable or satellite TV schemes, and this in turn allows minority interest or specialist channels to be provided economically.

Another possibility is the provision of commercial private closed user group' channels which may only be distributed to those lines by specific content providers, such as retail outlets and bank branches. Such contents will not be accessible by the general subscription users but will only be made available to specific users as predetermined by the content owners. Unlike conventional cable TV and satellite TV schemes, these contents will never be transmitted to the general subscription users and cannot therefore be accessed by tampering with the decoders at the users' premises.

Within or provided to the DSLAM 400 is a Conditional Access Unit or CAU 410 that routes the chosen programme

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channels to the respective subscriber lines 330 leading therefrom. The CAU 410 is connected by dedicated links to both the IP multicast and core networks 322 and 324. The channels are fed from the head end source 200 via the IP multicast network 322 to the CAU 410 for subsequently routing in a controlled manner based on subscription.

The CAU 410 includes data memory which keeps a customer profile for each subscriber and identifies the permissible or subscribed programme channel combination for the corresponding subscriber line 330. Based on the customer profiles, the CAU 410 determines, permits or denies, access to the channels via the subscriber lines 330. In particular, the CAU 410 is able to deny access to any channels, for example due to non-subscription in the payTV service, failure to pay outstanding bills, or total denial in the case of private channels that are receivable only by a limited and pre-defined closed user group for example in a business application. This feature provides highly secure control over unauthorized access to channels, in comparison to the cable TV or satellite TV systems, because denied channels are never transmitted to th diita1 dode 334 and are therefore incapable of unauthorized access by users.

a I I ** I. I I * * a a SI * * * SI! * I I * a I. a * a S S a *., Ia A large number of the DSL7Ws 400, with individual CAU 410, are connected to the IP network 320 for serving subscribers at different buildings or areas. The maintenance and control of the customer profiles in all the CAU's 410 is provided from a Conditional Access Gateway or CAG 420 connected between the IP core network 324 and an Operational Support System or OSS 500. Also connected between the IP core network 324 and the OSS 500 is the MVP 100.

In a conventional system of broadcast or multicast video distribution service for free-to-air channels, the choice of prograes or channels will not vary between different subscribers. But for payTV services, it is coon practice to bundle groups of channels (say 5-20 channels per bundle) as subscription service options. This arrangement requires a customer's service request (typically made by telephone) to be logged into the OSS 500, which has the capability to validate the appropriate payTV channels in the relevant digital decoder 334, while also providing billing data to enable invoicing of customers.

In the described IP multicast service, the payTv service is implemented based on the memory data, i.e. customer * I * * * * * * * * ** I. *. I I I * S S * S S 4** 4* * S S profiles, stored in the CATJ's 410 to allow or deny access to each channel. All the CALl's 410 are connected over the IP core network 324 to the CAG 420, which includes a database that contains all the conditional access data (customer profiles) for every CALl 410 and can issue instructions to each CALl 410 for changes in subscribers' channel access needs. The AG 420 is in turn synchronized with a database in the OSS 500, which retains the customer channel subscription data as well as the billing data. Thus, customer requests can be processed through the OSS 500 to update the customer access capability as well as billing/invoicing data.

The conventional arrangements have been satisfactory for both free-to-air and payTV services with a limited number of channels, but the subject IP multicast technology allows access to many hundreds of channels. The conventional channel bundling approach limits the variations in billing entities for convenience, but does not allow the customers to match their individual needs.

It is also common with the OSS 500 conventionally that a request for service change cannot be accommodated quickly, sometimes taking several hours.

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a S S * S S It. *i The ideal approach would be for any customer to be able to subscribe to any of several hundred individual channels, to do so by direct command from the remote control unit 335 of the digital decoder 334, and to receive service almost iuimediate.y within a minute or less. The channel access profile of each customer may differ from all others, and to manage such a service it is also desirable to provide each subscriber with a personalized electronic programme guide (EPG) relating to the subscribed channels. These requirements can create major cost penalties if implemented in the OSS 500 or the CAU 410 and CAG 420 systems alone.

The MVP 100 is connected to the I? core network 324 for communication with the CAG 420. Each subscriber can communicate using the remote control unit 335 of his/her digital decoder 334 with the MV? 100 via the IP network 320.

The MVP 100 is implemented by a conventional computer server that includes data memory and processing capabilities, and IP communication access lines connected to the OSS 500 and the I? core network 324 and hence indirectly to the CAG 420. The MV? data memory contains a master network customer database that includes the * * I. I I * * I I * * I I II I. I. * * * * I * I S * * * customer profiles of all subscribers, with the GAG 420 being a slave to the MVP 100. Thus, the MVP 100 keeps a master copy of the customer profiles, based on which the customer profiles in the CAG 420 (and hence those in the OSS 500 through synchronisation) are regularly updated for in turn updating the customer profiles in each CAU 410 associated with the GAG 420.

The MV? 100 also creates a web page of the prograiame guide for display on the subscriber's TV set 336 to show subscription information according to the corresponding customer profile. Conventional browser technology including a browser resident in the digital decoder 334 is used to view and operate the web page, thereby enabling interactive on-line activities by the subscriber.

To subscribe or unsubscribe a specific channel, the subscriber should identify the channel using up-down controls on the prograitime guide and key in a subscribe/unsubscribe conunand on the remote control unit 335. This command is transmitted in I? format from the digital decoder 334 via tho DSLM 400 (without encountering the associated CAU 410) and the I? core network 324 to the MV? 100. The MVP 100 then updates the S * S * * I S * *

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corresponding customer profile in its database, and issues appropriate commands to the CAG 420 and the OSS 500 to make corresponding updates in their databases. The CAG 420 subsequently commands the subscriber' s CAU 410 to change the status for that channel'.

Finally, the MVP 100 will transmit a revised programme guide page to the subscriber's TV set 336 via the browser of the digital decoder 334, confirming that the instruction has been received and implemented. Al].

subscribed channels are preferably highlighted.

It is noted that the database of the OSS 500 need not be updated before the subscriber instruction is confirmed, to speed up the process.

For security and other reasons, the CAG 420 is barred from receiving control signals directly from the remote control units 335. Thus, changes to individual customer profiles in the CAU 410 can only be entered via the CAG 420 by way of browser access using the MVP 100 or from the OSS 500 as a result of a telephone request from the customer concerned.

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- 14 - The same process can also be used to enable or disable parental control, in which a specific subscribed channel can only be accessed using a password known to some users of a subscriber line 330..

To select a subscribed channel for viewing the programme, the subscriber may identify the channel using the numeric keypad on the remote control unit 335 or using the up- down controls on the programme guide, then followed by a view key command from the control unit 335. This command is transmitted from the digital decoder 334 via the DSLAM 400 to the CAU 410, which in turn permits access to the channel if the relevant customer profile agrees.

The MV? 100 is also able to provide billing information to each subscriber. A billing request from the remote control unit 335 via the DSLAM 400 and the I? core network 324 to the MV? 100 will cause the MV? 100 to access the OSS 500 for retrieving the up-to-date billing status for the subscriber. This data is then formatted into an I? page and transmitted via the CAtJ 410 to the browser of the digital decoder 334 for display as a page on the subscriber's TV set 336.

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b IS S The I4VP 100 makes possible interactive on-line activities between the subscribers and the system operation, which is especially critical to selection at will of programme channels out of a large number of available choices. The activities include subscriptioz or cancellation of individual channels and setting or deactivation of parental control (relating to customer profiles). Other activities are billing enquiries, reviewing an electronic programme guide, and obtaining usage and customer training information for example in the form of a help menu.

The subject digital multicast system allows the customers to subscribe to individual channels to match individual user requirements and provides virtually instant subscription to individual new channels, even if there are many hundreds of channels. The access profile, i.e. channels that are subscribed and may be accessed, for one customer may be different from any other.

Uowever, with a large number of available channels it becomes increasingly difficult for the customers to be aware of all the channel contents that are currently available. Conventional advertising of channels in print media or on a separate channel promoting the programmes S S 55 S I. S I S * * S S IS *5 III * S I S S S I I * Is, S. * I S are helpful, but relatively expensive and ineffective for specialist channels having little mass market appeal.

According to the present invention, the conditional access facility in the DSLAM 400 is provided with four states applicable to the programme channels relative to the customers in the customer profiles, rather than the simply two "Subscribed" and "Denied" options as are found in typical payTV services.

The third state is known as the "Preview" option, which allows temporary viewing of an unsubscribed channel for a limited period and on a limited number of occasions. At the completion of the limited period, the video and/or audio signals will be disconnected by the CAU 410. The Preview option thus allows customers to form an immediate opinion of the nature and quality of the unsubscribed channel to assist in the subscription decision, which cannot be performed using the conventional advertising means. The number of access occasions can be limited in any daily period.

The fourth state is known as the "Private" option, in which the channels cannot be subscribed by the end users but can only be nominated by the content providers and * * . a. S * * S * I * S * * * S * *5 *. S * S S S S I S * I.. ** . . S validated over the I? core network 324, not from the end users' remote control units 335. The Private option allows the creation of Closed User Groups or CUG, in which each authorised CUG user can also have the normal subscription access to all the public channels.

The data memory of the CAU 410 in the DSLN 400 holds and defines which one of the four possible access states applies to each channel for each customer line 330. The CAU memory in turn is a partial copy of the network-wide database held in the MVP 100. In the case of Private channels, the denied status can only be modified by a customer service representative accessing the MTP 100. In the case of a permitted but unsubscribed Preview channel, the customer can subscribe directly from his/her remote control unit 335, as described above.

A preview channel will be provided from the DSLAN 400 to the digital decoder 334 requesting the same for a limited predetermined interval of typically 3 minutes for preview, after which the video and audio streams will be disconnected. Repeated attempts to access the same channel will be permitted for up to a predetermined maximum number of times, such as three attempts over a 24 hours period. An alternative option is to provide a * * S * I. I * * S S S * I I * * S S SI * S. 115 I * S S I. S S S -18- III blackout' period which prevents a repeated access to the same channel for a predetermined period of say several minutes izximediately following the access.

The Preview facility may be made available to only some of the channels and especially the new channels for promotion. As the channel under Preview will be disconnected at the end of the preview period and that period is short, security is not sacrificed.

A further option is to provide in the digital decoder 334 a superimposed browser capability which announces that a specific channel currently under preview is unsubscribed and offers instructions, on the electronic progranime guide provided by the MVP 100, to promote on-line subscription. The promotion text/images may cover all or part of the screen, thereby obscuring the preview for security, and sound may also be disconnected (by the decoder 334) for the same reason. This browser capability employs the customer's preferred language, and will be superimposed before the preview period in the DSLM 400 expires.

The invention has been given by way of example only, and various modifications of and/or alterations to the * * * * U. U. * * . I S I * S I * * S S IS * ** III S U I S -19- .:. .. : .*. **.

described embodiment may be made by persons skilled in the art without departing from the scope of the invention as specified in the appended claims. * a S * a

Claims

*5 S S S S * a.: *. * * a * -20- .* ** : . CLAIMS

1. A digital multicast system for distributing channels of multimedia programmes from a programme source to a plurality of subscriber locations over a digital network, comprising: a digital subscriber line access multiplexer connected by said network to said programme source for receiving said programme channels; a plurality of data lines connected from the multiplexer to said locations for transmitting said programme channels thereto; a conditional access unit associated with the multiplexer and including a data memory for storing a customer profile for each subscriber including channels subscribed thereby, the conditional access unit being adapted to permit or deny access to said programme channels by each subscriber based on the corresponding customer profile; and a digital decoder provided at each said location and connected to the corresponding data line for processing incoming programme signals and accessing the correpond.ng cu3tomer profile; wherein the conditional access unit is adapted to identify a preview state for an unsubscribed channel for I ** * * : * * * : * * * * : * : : : : : * I S -21- . a subscriber arid to permit limited access to said channel by said subscriber for temporary viewing thereof.

2. The digital multicast system as claimed in claim 1, wherein the limited access to said channel is limited to a predetermined interval of time.

3.0. A digital multicast system substantially as hereinbef ore described with reference to the accompanying drawing.

3. The digital inulticast system as claimed in claim 2, wherein the limited access to said channel is repeatable for a predetermined number of times over a predetermined period of time.

4. The digital multicast system as claimed in claim 2, wherein the limited access to said channel is not repeatable for a predetermined period of time following the access.

5. The digital multicast system as claimed in any one of claims 1 to 4, wherein the preview state is included in the customer profile for said subscriber.

6. The digital multicast system as claimed in any one of claims to 5, including a multica3t video portal connected by said network to the conditional access unit to enable on-line updating of the customer profiles by a a * *1 S * * S * * a S * I. **f S S S S

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the subscribers, the multicast video portal being acceSsible by said subscriber using the corresponding digital decoder via the multiplexer to subscribe to said channel.

7. The digital multicast system as claimed in claim 6, wherein the digital decoder includes browser means to promote subscription to said channel.

8. The digital multicast system as claimed in claim 6 or claim 7, wherein the multicast video portal includes a database including a master copy of the customer profiles, based on which the customer profiles in the conditional access unit are to be updated.

9. The digital multicast system as claimed in any one of claims 1 to 8, wherein the conditional access unit is adapted to identify a private state for a specific channel for access by subscribers predetermined by a content provider of said channel.