BANDWIDTH MANAGEMENT ON A HYBRID POINT TO POINT BROADCAST

Abstract: A system and method implemented in an interactive television system for managing transmission of data over broadcast and point-to-point channels. In one embodiment, the system comprises a broadcast station (10), a plurality of receiving stations (20), a broadcast channel through which data can be transmitted from the broadcast station to the receiving stations, and a plurality of point-to-point channels (13), each of which is between a corresponding one of the receiving stations and the broadcast station. The broadcast station monitors the demand for particular pieces of information and determines whether the information should be delivered via the broadcast channel or the point-to-point channels. Higher-demand pieces of information are broadcast cyclically over the broadcast channel, while lower-demand information is transmitted over the point-to-point channels.

Description: TITLE: BANDWIDTH MANAGEMENT ON A HYBRID POINT TO POINT BROADCAST BACKGROUND OF THE INVENTION 1 Field of the Invention The invention relates to interactive television systems and more particularly to optimization of data delivery in an interactive television system which has both a broadcast channel and a point-to-point channel. 2 Description of the Related Art Interactive television systems can be used to provide a wide variety of services to viewers Interactive television systems are capable of delivering typical video program streams, interactive television applications, text and graphic images, web pages and other types of information. Interactive television systems are also capable of registering viewer actions or responses. Interactive television systems can be used for such purposes as marketing, entertainment and education Users may interact with the systems by ordering advertised products or services, competing against contestants in a game show, requesting specialized information regarding particular programs, or navigating through pages of information Typically, a broadcast service provider generates an interactive television signal for transmission to a viewer's television. The mteractive television signal may include an mteractive portion consisting of application code or control information, as well as an audio-video portion consisting of a television program or other informational displays. The broadcast service provider combmes the audio-video and interactive portions mto a single signal for transmission to a receiver connected to the user's television. The signal is generally compressed pπor to transmission and transmitted through typical broadcast channels, such as cable television (CATV) lines or direct satellite transmission systems. The interactive functionality of the television is controlled by a set-top box connected to the television. The set-top box receives the signal transmitted by the broadcast service provider, separates the interactive portion from the audio-video portion and decompresses the respective portions of the signal. The set-top box uses the interactive information, for example, to execute an application while the audio-video mformation is transmitted to the television. The set-top box may combine the audio-video mformation with mteractive graphics or audio generated by the mteractive application prior to transmitting the mformation to the television. The interactive graphics and audio may present additional information to the viewer or may prompt the viewer for mput. The set-top box may provide viewer put or other information to the broadcast service provider via a modem connection. By their nature, interactive television systems provide vaπous different pieces of information which may be displayed to a particular viewer. The mteraction of the viewer with the system determines which of the information is presented to him or her as well as what information is transmitted from the viewer back to the system Interactive television systems may therefore have to transmit large amounts of mformation to a group of viewers because each of the viewers may request different pieces of the mformation. As a result of the demand for such large amounts of data, the bandwidth of the system may be insufficient to provide the mformation to the viewers within a sufficiently short response time. SUMMARY OF THE INVENTION The invention provides a method and apparatus for managing an interactive television system to optimize usage of the available bandwidth and minimize the system's response time. In one embodiment, the interactive television system comprises a broadcast station, a plurality of receiving stations, a broadcast channel through which data can be transmitted from the broadcast station to the receiving stations, and a plurality of point-to-point channels, each of which is between a corresponding one of the receiving stations and the broadcast station. Data can be transmitted from the broadcast station over each of the point-to-point channels to the respective receiving stations, as well as from the receiving stations to the broadcast station. The broadcast station monitors the demand for particular pieces of information and determines whether the information should be delivered via the broadcast channel or the point-to-point channels. In one embodiment, the interactive television system is configured to deliver requested web pages from the broadcast station to the receiving stations. Each of the receiving stations is configured to transmit requests for particular web pages to the broadcast station and to display the requested pages when they are received from the broadcast station. The broadcast station is configured to cyclically broadcast a certain number of web pages on the broadcast channel. After each of the pages has been broadcast once, the series repeats and each of the pages is broadcast again. The broadcast station is also configured to transmit individual web pages on the point-to-point channels. The broadcast station monitors the requests from the receiving stations and determines which of the requested pages are in higher demand. The pages which have the greatest demand are transmitted to all of the receiving stations on the broadcast channel. Pages which were requested by a particular receiving station are displayed by that receiving station. Pages which were not requested are ignored. Pages which have been requested by fewer receiving stations can be transmitted via the point-to-point channels of the respective receiving stations. Thus, the broadcast channels are used primarily to transmit pages which are requested by a large number of viewers, while the point-to-point channels are used to transmit pages which are requested by a small number of viewers. The use of the system's available bandwidth is thereby used in a way that minimizes the response time between a receiving station's request for a page and delivery of the page to the receiving station. While this embodiment comprises a system for delivering web pages, it is understood that other embodiments may be configured to deliver interactive television applications, multimedia data, or other types of information. BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the accompanying drawings in which: Fig. 1 is a block diagram illustrating the distribution of interactive television applications and television programs from their sources to a series of viewers. Fig. 2 is a block diagram illustrating the interconnection of a broadcast station and several receiving stations in one embodiment of the invention. Fig. 3 is a functional block diagram illustrating the flow of information through the broadcast station in one embodiment of the invention. Fig 4 is a block diagram of a set-top box used in one embodiment of the mvention While the mvention is susceptible to vaπous modifications and alternative forms, specific embodiments thereof are shown by way of example m the drawings and will herein be descπbed m detail It should be understood, however, that the drawings and detailed description thereto are not intended to limit the mvention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spiπt and scope of the present mvention as defined by the appended claims DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT One embodiment of the mvention is descπbed below In this embodiment, an mteractive television system mcludes a broadcast station and a number of receivmg stations The broadcast station and receivmg stations are coupled by a broadcast channel such as direct satellite transmission ("Broadcast" is used herem to refer to transmission of a smgle signal to all subscπbmg receivers "Direct" satellite transmission as used herem contemplates transmissions received by the mteractive television receiver, through its antenna, directly from the satellite ) The broadcast station and receivmg stations are also connected by several pomt-to-pomt channels, each of which forms a direct channel between the broadcast station and one of the receivmg stations The broadcast and pomt-to-pomt channels may both be used to transmit vaπous pieces of data to the receivmg stations The data may be audio-video-interactive mformation, such as mteractive application modules, or any other type of data, such as web pages The embodiment descπbed below is configured to transmit web pages The descπption of this embodiment, however, is mtended to be illustrative rather than limiting, and the transmitted data can represent any type of mformation, such as application code, raw data or graphical information In the descπbed embodiment, the receivmg stations are configured to transmit mformation requests to the broadcast station The mformation requests transmitted by a particular receivmg station correspond to web pages which the user at the receivmg station wishes to view The broadcast station receives the requests and retrieves the requested pages from the appropnate sources After the requested pages have been retrieved by the broadcast station, they must be transmitted to the receivmg stations which submitted the corresponding requests The retrieved pages may be transmitted to the receivmg stations via either the broadcast channel or the pomt-to-pomt channels Data transmitted via the broadcast channel is distπbuted to all of the receivmg stations, whether they requested the transmitted pages or not Data transmitted via the pomt-to-pomt channels is distπbuted only to those receivmg stations which requested it, but the broadcast station can only transmit a limited amount of data at one time Rather than usmg only one of these channels to transmit data to the receivmg stations, this embodiment of the mvention can use both That is, a particular piece of data such as a web page can be transmitted over either channel Because the pomt-to-pomt channel is not limited to transmitting only narrow-band data, entire web pages can be transmitted over this channel. The broadcast stanon need not stπp out narrow-band data for transmission over the pomt-to-pomt channel while wide-band data is transmitted over the broadcast channel Similar data (e g , wide-band data) can be transmitted over either the broadcast channel or the pomt-to-pomt channel. Consequently, the decision to transmit particular data over one channel or the other can be based on delivery times or other quahty-of-service cπteπa. There are a number of factors which influence the decision to transmit data over one channel or the other. For example, smce some of the retπeved pages may have been requested by more than one receivmg station, it may be more efficient to transmit these pages via the broadcast channel, while pages requested by a smgle receivmg station may be more efficiently transmitted via the pomt-to-pomt channel In another example, mteractive application modules which are needed by larger numbers of subscπbers may be transmitted via the broadcast channel, while modules which are needed by fewer subscπbers may be transmitted via the pomt-to- pomt channels Thus, m some instances, it may be advantageous to transmit data over the broadcast channel. For example, when the point-to-pomt channel would require an mordmately large amount of time to deliver the data or when transmission over the broadcast channel is necessary to meet quahty-of-service cπteπa, the broadcast channel is selected for transmission of the data. The broadcast station may therefore momtor the requests from the receivmg stations to determine which of the pages are m greater demand (i.e., which are requested by a greater number of receivmg stations.) When the requested pages are retπeved, those which are m the greatest demand are transmitted via the broadcast channel In other instances, it may be advantageous to transmit data over the pomt-to-pomt channel. For example, when the broadcast channel is heavily loaded with transmission of high-demand data, it may be preferable to transmit a module which has been requested by a smgle subscπber via the pomt-to-pomt channel. There may also be instances m which the transmission quality of the pomt-to-pomt channel is greater than that of the broadcast channel, m which case certain modules may need to be transmitted via the point-to-pomt channel. Referring to Fig. 1 , a block diagram illustrating the distπbution of mformation such as web pages from their sources to a seπes of viewers is shown. (It should be noted that web pages are exemplary, rather than limiting, of the types of data which may be transmitted and other types of data, such as application modules, image data, and the like may also be transmitted m the vaπous embodiments of the invennon ) Broadcast station 10 has several program sources 11. In one embodiment, sources 11 are web servers which may be accessed by broadcast station 10 to obtam web pages. In other embodiments, the sources may include remote broadcast network feeds, videotape recorders, computers, data storage devices, and the like Sources 11 provide audio- video mformation which is to be mcluded m the mteractive television signal. The mformation from sources 11 is transmitted to receiving station 20 via either a broadcast channel or a pomt-to-pomt channel The broadcast channel is depicted m the figure as a direct satellite broadcast channel formed by broadcast antenna 12, communications satellite 15 and receivmg antenna 19 Although the figure illustrates a satellite transmission, it is contemplated that any broadcast medium, including non-satellite, CAIN (cable), telco (telephone), MMDS (microwave) and terrestπal transmissions, may be used. The pomt-to-pomt channel may compπse an ordinary telephone lme 13 connected to a transmitting modem m the broadcast station and a receivmg modem m the receivmg station (not shown) The pomt-to-pomt channel may compπse other transmission media m other embodiments. The pomt-to-pomt channel is typically used to transmit user data from the receivmg station to the broadcast station. The pomt-to-pomt channel also provides an alternate path for web pages and other pieces of information from sources 11 to be delivered to receivmg station 20. Referring to Fig 2, the interconnection of broadcast station 10 and several receivmg stations 20 is shown. (For convenience, items havmg reference numerals followed by a letter are collectively referred to by the reference numeral without a letter ) The figure illustrates that broadcast channel 14 transmits a smgle broadcast signal to each of receivmg stations 20, while point-to-pomt channels 13 separately connect each of the receivmg stations to the broadcast station A signal on one of the point-to-pomt channels is therefore mdependent of the signals on the other pomt-to-pomt channels Referring to Fig. 3, a functional block diagram illustrating the flow of mformation through broadcast station 10 is shown. In one embodiment, web pages are received from web servers via modem 21. The web pages may be compressed by compression units 22 m order to conserve bandwidth Any one of a number of compression algoπthms may be used if appropπate for a particular program or application. Some web pages may not be easily or effectively compressed, so some of the mformation may bypass compression units 22 and be passed from the modem to packetization units 23 without compressmg the mformation. Packetization units 23 accept the compressed (or uncompressed) mformation and format it mto packets for transmission over the broadcast channel. The figure also shows storage unit 24, which may provide previously obtained mformation, stored data or some other type of mformation to compression unit 22 and packetization unit 23. The components of broadcast station 10 are coupled to a control unit (not shown) which manages the functions of the broadcast station. The packets from packetization units 23 are fed mto multiplexing unit 25, which may intersperse the packets with each other or with control information pπor to transmission. The interspersed packets are then passed to proxy server 26 Proxy server 26 monitors the web page requests submitted by the users and determines the demand for the different web pages Typically, high-demand pages are transmitted on the broadcast channel, while lower-demand pages are transmitted via the point-to-pomt channel In the illustrated embodiment, the pomt-to-pomt channel is represented by modem 27, which transmits the page to a smgle user via a phone lme (not shown). While other types of controllers or processors could be used to implement the monitoring function of the broadcast station, a proxy server is used m this embodiment. In addition to monitoring the mformation requests, the proxy server can perform other flmctions, such as filtermg the requests or cachmg mformation responsive to the requests. The use of a proxy server may also mcrease the scalability of the system, as more proxy servers can be added to handle the load from the receivmg stations Because pages transmitted via the broadcast channel are received by all users, pages which have been requested by a large number of users are most efficiently distπbuted over this channel. Each of the requests can be serviced simultaneously and the response time is kept to a minimum Pages which are requested by smaller numbers of users may be more efficiently transmitted via the pomt-to-pomt channels between the broadcast station and the respective receivmg stations. It is also contemplated that the choice of channels may be based on anticipated demand, rather than the actual number of requests for particular pages For example, if a commercial for a certain manufacturer is broadcast, it may be anticipated that a large number of requests for that manufacturer's web page will be received The manufacturer's web page may therefore be transmitted over the broadcast channel while other web pages are transmitted over the pomt-to-pomt channels It is contemplated that the receivmg station may be configured to transmit pieces of information m a cyclic manner That is, a certain number of these pieces of mformation (e g , web pages) are transmitted one after the other and then, after each of the pieces of information has been transmitted a first time, they are transmitted a second time and a third time and so on The broadcast station thus continuously broadcasts data, with each piece of information bemg re-broadcast at regular intervals (1 e , each piece of mformation is re-broadcast with a certain frequency) The broadcast station may also be configured to transmit multiple carousels which have different peπodicities As noted above, the pieces of mformation which are broadcast m this manner may be referred to as a carousel Because there may be a limited number of positions or slots m the carousel, the broadcast station must pπoπtize the requested pieces of mformation The determination of whether a piece of mformation will be transmitted via the broadcast channel or the pomt-to-pomt channel depends on its pπoπty and the number of slots m the carousel If only a few web pages are requested by users, it may be possible to transmit all of them, including low-demand pages, via the broadcast channel In fact, the need to meet certain cπteπa for quality of service may influence the number of slots m the carousel and the peπodicity of carousel transmissions On the other hand, there may be mstances m which the number of high-demand pages exceeds the number of allowable slots m the carousel, and some of them may have to be transmitted via the pomt-to-pomt channel Vaπous strategies may be used to determine which pages are transmitted by which channel If one or more pages are m particularly high demand, they may be allocated two slots m the carousel so that it is transmitted with a greater frequency Responses to requests for these pages will therefore have a reduced latency (response time ) If there is a particularly large number of pages for which there is only a low or moderate demand, the size of the carousel may be mcreased (It should be noted that the carousel is not a hardware structure, and that the number of slots m the carousel is determined by the system software based on system and performance constraints ) The strategy for routmg data via the respective channels may also take into account other factors, such as degraded quality of transmissions on the pomt-to point channel For example, if a modem channel is too noisy to transmit error-free data, or if this channel simply doesn't meet the quahty-of-service cnteπa, the cyclic broadcast of high-demand data may be interrupted so that low-demand data can be transmitted over the broadcast channel Receivmg station 20 is contemplated to be one of a number of stations which are subscnbers of the broadcast service provider operating broadcast station 10 The broadcast signal is collected by receiving antenna 19 and fed to receivmg station 20, which in one embodiment is contemplated to be a set-top box coupled to a television set Set-top box 22 processes the packetized signal to reconstruct the mformation embodied m the signal (e g , web pages ) The reconstructed mformation is processed m the set-top box and, if appropπate, transmitted to the television to be displayed Web pages may be directed to the television, while mformation compπsmg an mteractive applications may be executed m the set-top box rather than bemg displayed Interactive applications may, however, generate graphics or audio which are combmed with other mformation and then displayed Referring to Fig. 4, a block diagram of a set-top box 22 is shown. The broadcast signal is received and fed into tuner 31. Tuner 31 selects a particular broadcast channel on which the broadcast audio-video-interactive signal is transmitted and passes the signal to processing unit 32. (Tuner 31 may be replaced by other means, such as simple input ports, for receiving signals from various signal sources.) Processing unit 32 demultiplexes the packets from the broadcast signal if necessary and reconstructs the information embodied in the signal. The information is then decompressed by decompression unit 33. The information is then conveyed to display unit 34, which may perform further processing and conversion of the information into a suitable television format, such as NTSC or HDTV audio/video. If the information includes interactive applications, these applications are reconstructed and routed to random access memory (RAM) 37. The applications are then executed by control unit 35. Control unit 35 may include a microprocessor, micro-controller, digital signal processor (DSP), or some other type of software instruction processing device. RAM 37 may include memory units which are static (e.g., SRAM), dynamic (e.g., DRAM), volatile or non-volatile (e.g., FLASH), as required to support the functions of the set-top box. When power is applied to the set- top box, control unit 35 executes operating system code which is stored in ROM 36. The operating system code executes continuously while the set-top box is powered in the same manner the operating system code of a typical personal computer (PC) and enables the set-top box to act on control information and execute interactive and other applications. The set-top box also includes modem 38. Modem 38 is connected to the telephone line which provides the point-to-point channel between the receiving station and the broadcast station. This channel may serve both as a means for transmitting requested data from the broadcast station to the receiving station and as a return path by which the user can transmit information requests to the broadcast station. Set-top box 22 may include a module manager unit 30 contained within control unit 35. Since the receiving station is not aware of the whether it has requested modules which are in high demand from other receiving stations, module manager unit 30 monitors tuner 31 and modem 38 for the requested information. (Tuner 31 in this case is the receiving station's connection to the broadcast channel and modem 38 is its connection to the point-to-point channel.) In other embodiments, the receipt of requested information may be controlled in a different manner. For example, the broadcast station may be configured to transmit notification to the receiving station on a predetermined channel to inform the receiving station which of the channels will be used to transmit the requested information. In one embodiment, module manager unit 30 is implemented in software, but it may also be implemented in hardware or a combination of hardware and software. Module Manager unit 30 may be used to control the receipt of audio-video information via the broadcast and point-to- point channels. Although the term "set-top box" is used herein, it is understood that this term refers to any receiver or processing unit for receiving and processing a transmitted signal and conveying the processed signal to a television or other monitor. The set-top box may be in a housing which physically sits on top of a television, it may be in some other location external to the television (e.g., on the side or back of the television or remotely located from the television), or it may be incorporated into the television itself. Set-top box 22 serves to demodulate the signal received from broadcast station 10 and to separate the components of the signal, such as web pages, television programs and interactive applications. Similarly, the television set may be a television or a video monitor employing any suitable television format (e.g., NTSC or HDTV), or it may be replaced by other devices, such as a video recorder. In the embodiment described above, the broadcast channel is a direct satellite transmission channel. The broadcast channel may alternately utilize various transmission media and is contemplated to include media such as coaxial cable and free space (e.g., as used for direct satellite transmissions.) The return path typically consists of a pair of modems, one in the receiving station and one in the broadcast station, each connected to a standard telephone line. Other means for establishing a return path, however, are also contemplated. For example, a portion of the bandwidth of the transmission path could be used as the return path. If the return path utilizes a portion of the broadcast bandwidth, it is contemplated that the broadcast station may still employ a separate point- to-point channel (e.g., a telephone line) to transmit requested data to the receiving station. In considering the alternate embodiments of the invention, it may be helpful to view the channels of communication between the broadcast station and receiving station as three logical links: a broadcast link; a point-to-point link; and a return link. As described above, the broadcast link is used to transmit data to multiple receiving stations. The point-to-point link is used to transmit data to individual receiving stations. The return link is used to transmit data to the broadcast station. These logical links may be mapped to a wide variety of physical media, some of which are shared (e.g., satellite transmissions) and some of which are separate, or point- to-point (e.g., telephone lines). More specifically, the broadcast logical link must be mapped to one of the shared media. The point-to-point and return links may be mapped to either the shared media, or the separate media. It is even possible to split the logical links and map them to more than one medium. For example, a point-to-point logical link may be mapped to a shared medium such as a satellite (for transmissions to the receiving station) and at the same time mapped to a separate medium such as a telephone line (for transmissions to the broadcast station). Just as various aspects of the invention described above may vary in different embodiments of the invention, other details of these embodiments may also be modified without departing from the spirit and scope of the invention as defined by the appended claims. The embodiments described above are intended to be exemplary rather than limiting, and it is contemplated that the scope of the invention includes various modifications and embodiments which will be apparent to those skilled in the art of the invention.

Claims: WHAT IS CLAIMED IS: 1. In an mteractive television system havmg a plurality of receivmg stations, a broadcast station compπsmg- a broadcast channel coupled to each of said receivmg stations, said broadcast channel bemg configured to simultaneously transmit mformation to all of said receivmg stations; a plurality of pomt-to-pomt channels, each said pomt-to-pomt channel coupled to a corresponding one of said receivmg stations, each said pomt-to-pomt channel bemg configured to transmit mformation to said corresponding one of said receivmg stations, each said pomt-to-pomt channel bemg further configured to transmit requests to said broadcast station; and a control unit configured to monitor a plurality of requests from said receivmg stations, each said request indicating a corresponding piece of mformation for each said piece of mformation, select one of said broadcast channel and said pomt-to-pomt channels for transmission of said piece of information, and transmit each said piece of information via said one of said broadcast channel and said pomt-to- pomt channels selected for said piece of mformation 2. The mteractive television system of claim 1 wherem said control unit is configured to associate a demand level with each said piece of mformation based at least m part on the number of requests for said piece of information and to select said broadcast channel if said associated demand level is above a threshold level and to select said pomt-to-pomt channel if said associated demand level is below said threshold level 3. The mteractive television system of claim 2 wherem each of said pomt-to-pomt channels compnses a telephone lme. 4. The mteractive television system of claim 3 wherem said pomt-to-pomt channels are configured to serve as a return path between said broadcast station and said receivmg stations. 5. The mteractive television system of claim 1 wherem said control unit is coupled to a plurality of mformation sources, wherem said control unit is configured to obtam said pieces of mformation from said mformation sources, and wherem each of said broadcast and pomt-to-pomt channels is configured to transmit said pieces of information from each of said mformation sources 6 The mteractive television system of claim 5 wherem one of said mformation sources is a storage unit for said pieces of mformation. 7 The mteractive television system of claim 1 wherem said pieces of mformation assigned to said broadcast channel form a carousel and wherem said broadcast station is configured to transmit said pieces of mformation in said carousel m a cyclic manner. 8. The interacnve television system of claim 7 wherem said carousel has a plurality of slots and wherem one of said pieces of mformation occupies more than one of said slots 9 The mteractive television system of claim 8 wherem said pieces of information compπse web pages. 10. The mteractive television system of claim 1 wherem said broadcast channel and said pomt-to-pomt channels are configured to transmit identical types of said pieces of information 11. A method for managmg the transmission of data from a broadcast station to a plurality of receivmg stations wherem each receiving station is coupled to the broadcast station by a broadcast transmission channel and a pomt- to-pomt transmission channel, the method compπsmg: transmitting a plurality of mformation requests from said receiving stations to said broadcast station, monitoring said mformation requests; obtaining pieces of data corresponding to said mformation requests, assignmg said pieces of data to be transmitted to one or more of said receivmg stations via one of said broadcast transmission channel and said pomt-to-pomt transmission channel; and transmitting said pieces of data to one or more of said receivmg stations. 12. The method of claim 11 further compπsmg pπoπtizmg said mformation requests and assignmg said pieces of data to be transmitted to one or more of said receivmg stations via one of said broadcast transmission channel and said pomt-to-pomt transmission channel based on said pπoπtization of said corresponding mformation requests 13. The method of claim 12 wherem monitoring said mformation requests compπses counting a number of requests corresponding to each said piece of data. 14. The method of claim 13 wherem pπoπtizmg said mformation requests compπses assignmg a pπoπty to each of said information requests, said pπoπty bemg higher if said number of requests is higher and lower if said number of requests is lower; and wherem assignmg said pieces of data to one of said broadcast transmission channel and said pomt-to- pomt transmission channel mcludes assignmg each said piece of data to said broadcast transmission channel if said piece of data corresponds to a high pπoπty mformation request; and assignmg each said piece of data to said pomt-to-pomt transmission channel if said piece of data corresponds to a low pπoπty mformation request 15. The method of claim 14 wherein transmitting said pieces of data comprises: transmitting said pieces of data corresponding to said high priority information requests in a cyclic manner on said broadcast transmission channel; and transmitting said pieces of data corresponding to said low priority information requests on ones of said point-to-point transmission channels corresponding to said low priority information requests. 16. The method of claim 11 wherein each of said broadcast channel and said point-to-point channel are configured to transmit similar types of data and wherein assigning said pieces of data to one of said broadcast transmission channel and said point-to-point transmission channel is based on one or more quality-of-service criteria. 17. An interactive television system comprising: a broadcast station; a plurality of receiving stations; a broadcast channel coupled to said broadcast station and said plurality of receiving stations; and a plurality of point-to-point channels, wherein each of said point-to-point channels is coupled to a corresponding one of said receiving stations and to said broadcast station and wherein each said point-to-point channel is configured to transmit the same type of data as said broadcast channel; wherein said receiving stations are configured to transmit information requests to said broadcast station; and wherein said broadcast station is configured to monitor said information requests and select one of said broadcast and said point-to-point channels for transmission of pieces of information responsive to each said information request and transmit said pieces of information responsive to each said information request via said selected channel. 18. The interactive television system of claim 17 wherein said broadcast station is configured to select said broadcast and said point-to-point channels for said pieces of information based on a number of said information requests corresponding to each said piece of information. 19. The interactive television system of claim 18 wherein said pieces of information comprise a first group and a second group, each said piece of information in said first group corresponding to at least a first number of said information requests, each said piece of information in said second group corresponding to no more than said first number of said information requests. 20. The interactive television system of claim 19 wherein said broadcast station is configured to transmit said pieces of information in said first group via said broadcast channel. 21. The mteractive television system of claim 20 wherem said broadcast station is configured to transmit said pieces of information m said first group m a cyclic manner 22. The mteractive television system of claim 21 wherem said broadcast station is configured to transmit each of said pieces of mformation m said first group with a correspondmg frequency, and wherem said frequency of one or more of said pieces of mformation is higher than said frequency of the remamder of said pieces of information. 23. The mteractive television system of claim 17 wherem said broadcast station is configured to transmit to said receivmg station via a predetermined one of said broadcast channel and said pomt-to-pomt channels a signal correspondmg to one of said pieces of mformation, said signal mdicatmg which of said broadcast channel and said pomt-to- pomt channels will be used to transmit said correspondmg piece of information and wherem said receivmg stations are configured to monitor said predetermined one of said broadcast channel and said pomt-to-pomt channels for said signal and to receive said correspondmg piece of information on said one of said broadcast channel and said pomt-to-pomt channels mdicated by said signal 24. The mteractive television system of claim 17 wherem said receivmg stations are configured to monitor said broadcast channel and said pomt-to-pomt channels for said pieces of information.

Inventors: DUREAU VINCENT, DUREAU, VINCENT
Applicants: OPENTV INC, OPENTV, INC.
Application year: 2000
Main classification: H04N7
IPC codes: H04H1, H04H7, H04N7