WO2005055603A1

WO2005055603A1 - A method of enhancing data transfer

Info

Publication number: WO2005055603A1
Application number: PCT/GB2004/004368
Authority: WO
Inventors: Peter William Wild
Original assignee: Roke Manor Research Limited
Priority date: 2003-11-19
Filing date: 2004-10-14
Publication date: 2005-06-16
Also published as: GB2408402A; GB0327030D0

Abstract

A method of enhancing data transfer in a communication system comprising a transmitter and at least one receiver comprises setting access criteria for at least first and second data sources (3, 4) to non-subscribed and subscribed modes respectively. The first and second data sources are transmitted on a single frequency communication channel (9) from the transmitter to the or each receiver; and the second data source comprises the same type of data as the first data source transmitted at a higher resolution, higher data rate, or enhanced quality. The first data source is decodable at receivers in both subscribed and non-subscribed mode. The second data source is decoded only at receivers operating in subscribed mode.

Description

A METHOD OF ENHANCING DATA TRANSFER This invention relates to a method of enhancing data transfer in a communication system. There are a number of situations in which data transmission is carried out using different mechanisms in a communication system. A particular example is transmission of television programmes. For example, a programme's vision content is transmitted using amplitude modulation, while its sound content is transmitted via frequency modulation. It may be that a programme can be broadcast free to any user with a suitable receiver or it may be intended only for subscribers who have paid for the service. One way in which access control is achieved, taking advantage of the different mechanisms, is by using different mediums for reception, i.e. a standard TV aerial for the free broadcast and a cable system for the subscription service. Another is to encrypt the transmission and only issue the means to decode this to subscribers, e.g. using a set- top box. Broadcasters would like to tempt non-subscribers to take up their services, but there may be some reluctance if this involves purchasing and installing additional equipment. For example a set top box can receive free to view channels, and in addition has a smart card reader that allows viewers to subscribe and view additional channels by purchasing a suitable smart card In accordance with the present invention, a method of enhancing data transfer in a communication system comprising a transmitter and at least one receiver comprises setting access criteria for at least first and second data sources to non-subscribed and subscribed modes respectively; transmitting the first and second data sources on a single frequency communication channel from the transmitter to the or each receiver; wherein the second data source comprises the same type of data as the first data source transmitted at a higher resolution, higher data rate, or enhanced quality; wherein the first data source is decodable at receivers in both subscribed and non-subscribed mode; and wherein the second data source is decoded only at receivers operating in subscribed mode. Data transfer is enhanced in that the receiver is able to receive more than one data source simultaneously, so that all data sources can be sent in common over a single frequency communications channel, but the receiver only decodes all data sources if it is subscribed to the appropriate service for each. If the receiver is in non-subscribed mode, then it can only decode the first data source, or each data source which has been allocated for non-subscribed mode. Preferably, each data source is transmitted on a separate sub-channel of the single frequency communication channel. The number of data sources that can be transmitted and controlled is directly related to the number of sub-channels available. In general, the receiver uses the data from the second source on a second channel to either improve the quality of the data from the first source on a first channel, or to provide additional data content to enhance the data in the first channel. The second data source comprises the same type of data as the first data source, in a different format. This is particularly applicable where the supplier is trying to attract new custom, because a user receiving the low quality free service can simply pay to upgrade to the enhanced service. An example of this is where the first data source is one of a video stream, or share prices on an internet web page. The enhanced service provides the video stream at a higher resolution to give a better quality image or at a higher data rate to update the share price more frequently. Another example is the rate of updating of prices for goods or services on an auction web site. In an alternative example, the first data source is a black and white video stream and the second data source is a colour video stream. Here, the basic service (non-subscribed) provides black and white images and the enhanced service (subscribed) provides colour images. Preferably, the sub-channels are separated in time. Preferably, the communication system uses a single frequency, multiple channel system, such as time division multiple access (TDMA) or code division multiple access (CDMA). An example of a method of controlling data transfer according to the present invention will now be described with reference to the accompanying drawing in which:

Figure 1 is a block diagram illustrating one embodiment of the method of the present invention. A communication system 1, capable of transmitting data 2 via at least two subchannels 3, 4 within a transmission, receives data 2 from a data source and splits it into different data types in a data splitter 5. Data of a first type on the first sub-channel 3 is subjected to conditional access coding 6 and then coded 7 for transmission. Data of the second type is sent via an alternative path, sub-channel 4, direct to the coder 7. The two sub-channels are recombined and sent to a transmitter 8 which transmits them via an appropriate medium 9 to a dual channel receiver 10. The receiver in such a system is capable of decoding the transmitted data from the two sub-channels simultaneously. At the receiver the data in the respective subchannels 3, 4 are directed to a data fuser 12, the first sub-channel data having first passed through a conditional access decode 11. In the data fuser, the data is prepared for presentation according to whether the receiver is set-up in subscribed or non-subscribed mode and then presented accordingly in a data presentation stage 13. The communication system generally transmits to multiple users, each having a receiver, although, for simplicity, only one user and associated receiver is shown in this example. The non-subscribed mode data is broadcast, in the sense that it is available to any user with a suitable receiver, but the actual mechanism by which it is transmitted may be via an RF transmitter, a cable network, a mobile phone network, or any other suitable medium. Splitting the source data into two sub-channels allows low value data to be provided via one sub-channel, and high value data via the second sub-channel. If the system has provision for multiple sub-channels, then far more options are available to the service provider. Although these examples are directed to two sub-channels, the invention is not limited to this. A conditional access (CA) scheme is employed to limit access to the high value data, unless the user has subscribed and typically also paid a fee. Generally, the low value sub-channel reception is free, but this is not always the case and it is quite possible that the "non-subscribed" mode simply means that only a basic package has been purchased, whereas the "subscribed" mode allows the user access to the premium package. Different criteria can be used to define the high value data, for example, on the basis of its content value, or speed of delivery. The subscription content could be unique content or alternatively could be the same content as presented on the 'free to air' channel, only provided at a higher data rate, so enhancing the speed of response and hence user experience. A specific example is in the case of digital television, where a user might subscribe to a service which transmits a film at a higher resolution than the free service in order to get a better quality picture. Another example is a webpage with some data which is only visible to subscribers, e.g. stockmarket data giving yesterday's closing price for all to see and prices updated every minute for subscribing users only. Alternatively, the split channels enhance the response rate of what is otherwise the same information, e.g. that the webpage updates share prices once an hour on the non- subscribed service and every minute on the subscribed service. Another use is in providing common data via a mobile phone network, for example traffic information broadcast to all subscribed users under the control of a particular base station or within a specific cell. The presentation of data within the receiver will adapt depending on whether single or dual sub-channel reception is available, so that if only single channel reception is available, it can still decode the signal if the user has subscribed to the service. The examples have been given for two sub-channels in a single frequency channel, but the invention applies to any systems where there are at least two subchannels, so use of multiple sub-channels on a single radio frequency channel is equally applicable, such as is possible with TDMA or CDMA systems. Another example of a suitable technology is orthogonal frequency division multiplexing (OFDM) systems, such as digital audio broadcasting (DAB) or digital terrestrial television (DTT). In

OFDM, a data stream is divided into multiple parallel bit streams at a lower bit rate and these bit streams are used to modulate multiple carriers. A single channel, for example at 20MHz, is divided into multiple narrowband sub-carriers. The data streams are divided into symbols of fixed duration. This allows sub channels to be created from a number of these symbols within a time frame structure. The resulting data streams are multiplexed on to the single frequency channel and the receiver time aligns itself to receive a given sub-channel within a time frame structure. Typical frequencies for audio and video data via DAB would be 200MHz or 1.4GHz. Using a receiver which can decode multiple sub-channels within a given time frame, it becomes possible to 'integrate' the content from these respective channels to generate a composite service. Typically this will be multi-media data, presented via a User Interface (UI), typically a browser. Certain elements on the UI will be from one received sub-channel, others from the second. The data content from the two streams is seamlessly integrated from the respective sub-channels into a single user presentation.

Claims

1. A method of enhancing data transfer in a communication system comprising a transmitter and at least one receiver, the method comprising setting access criteria for at least first and second data sources to non-subscribed and subscribed modes respectively; transmitting the first and second data sources on a single frequency communication channel from the transmitter to the or each receiver; wherein the second data source comprises the same type of data as the first data source transmitted at a higher resolution, higher data rate, or enhanced quality; wherein the first data source is decodable at receivers in both subscribed and non-subscribed mode; and wherein the second data source is decoded only at receivers operating in subscribed mode.

2. A method according to claim 1, wherein each data source is transmitted on a separate sub-channel of the single frequency communication channel

3. A method according to claim 1 or claim 2, wherein the first data source is one of a video stream or share prices, on an internet web page.

4. A method according to claim 1 or claim 2, wherein the first data source is black and white video and the second data source is colour video.

5. A method according to at least claim 2, wherein the sub-channels are separated in time.

6. A method according to any preceding claim, where the communication system uses a single frequency, multiple channel system, such as time division multiple access (TDMA) or code division multiple access (CDMA).