Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
  • H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
  • H04N21/47—End-user applications
  • H04N21/472—End-user interface for requesting content, additional data or services; End-user interface for interacting with content, e.g. for content reservation or setting reminders, for requesting event notification, for manipulating displayed content
  • H04N21/4722—End-user interface for requesting content, additional data or services; End-user interface for interacting with content, e.g. for content reservation or setting reminders, for requesting event notification, for manipulating displayed content for requesting additional data associated with the content
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
  • H04N21/20—Servers specifically adapted for the distribution of content, e.g. VOD servers; Operations thereof
  • H04N21/23—Processing of content or additional data; Elementary server operations; Server middleware
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
  • H04N21/60—Network structure or processes for video distribution between server and client or between remote clients; Control signalling between clients, server and network components; Transmission of management data between server and client, e.g. sending from server to client commands for recording incoming content stream; Communication details between server and client 
  • H04N21/61—Network physical structure; Signal processing
  • H04N21/6156—Network physical structure; Signal processing specially adapted to the upstream path of the transmission network
  • H04N21/6181—Network physical structure; Signal processing specially adapted to the upstream path of the transmission network involving transmission via a mobile phone network
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
  • H04N21/60—Network structure or processes for video distribution between server and client or between remote clients; Control signalling between clients, server and network components; Transmission of management data between server and client, e.g. sending from server to client commands for recording incoming content stream; Communication details between server and client 
  • H04N21/65—Transmission of management data between client and server
  • H04N21/658—Transmission by the client directed to the server
  • H04N21/6581—Reference data, e.g. a movie identifier for ordering a movie or a product identifier in a home shopping application
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
  • H04N21/80—Generation or processing of content or additional data by content creator independently of the distribution process; Content per se
  • H04N21/81—Monomedia components thereof
  • H04N21/812—Monomedia components thereof involving advertisement data
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N7/00—Television systems
  • H04N7/16—Analogue secrecy systems; Analogue subscription systems
  • H04N7/173—Analogue secrecy systems; Analogue subscription systems with two-way working, e.g. subscriber sending a programme selection signal
  • H04N7/17309—Transmission or handling of upstream communications
  • H04N7/17336—Handling of requests in head-ends
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N7/00—Television systems
  • H04N7/16—Analogue secrecy systems; Analogue subscription systems
  • H04N7/173—Analogue secrecy systems; Analogue subscription systems with two-way working, e.g. subscriber sending a programme selection signal
  • H04N2007/1739—Analogue secrecy systems; Analogue subscription systems with two-way working, e.g. subscriber sending a programme selection signal the upstream communication being transmitted via a separate link, e.g. telephone line

Definitions

• This invention relates to methods and systems for delivering data over a network, particularly those for delivering a large amount of data with repetitive content to a large number of clients, like Video-on-Demand (NOD) systems.
• NOD Video-on-Demand
• a ⁇ VOD system consists of staggered multicast streams with regular stream interval T ( Figure 1).
• the streams are multiplexed onto the same or different physical media for distribution to the users via some multiplexing mechanisms (such as time- division multiplexing, frequency division multiplexing, code-division multiplexing, wavelength division multiplexing etc).
• the distribution mechanisms include point- to-point, point-to-multipoint and other methods.
• Each stream is divided into regular segments of interval T, and the segments are labelled 1, 2, 3, ..., ⁇ respectively.
• the content that is to be distributed to the users is carried on the ⁇ segments and the content is replicated on all these streams. The content is also repeated on each stream in time.
• QVOD Quasi-VOD with irregular stream-interval
• a QVOD system consists of staggered multicast streams with irregular stream intervals ( Figure 2).
• the streams are multiplexed onto the same or different physical media for distribution to the users via some multiplexing mechanisms (such as time- division multiplexing, frequency division multiplexing, code-division multiplexing, wavelength division multiplexing etc .).
• the distribution mechanisms include point- to-point, point-to-multipoint and other methods.
• the streams in a QVOD system are created on demand from the users' request for the content.
• the users' requests within a certain time interval l ⁇ are batched together and served together by Stream i.
• the stream intervals 71, 72, ... Ti, ... are irregular.
• the streams (Stream 1 to i etc%) are all provided on-demand and will be removed as soon as the content distribution has been completed.
• the streams are constantly created as users' requests come in.
• the particular group of users starting within interval Ti is guaranteed to receive the contents within 71 (start-up latency).
• start-up latency there is no provision for user interactivity in such a system. If a user interrupts the content viewing say by pausing the display, the user cannot resume the viewing at the same play point where the user pauses and is forced to skip some content to keep up with the multicast-stream that is continuously playing.
• DINA Distributed Interactive Network Architecture
• a user may have to wait as long as one stream interval T before the request is served, and the waiting time may be as large as many minutes or even hours, depending on the stream interval.
• the stream interval can be made very small, say even down to a few seconds, this also means that the system has to provide a large number of streams for serving the same amount of content.
• NVOD and QVOD systems cannot allow VCR-liked interactivity such as pause, resume, rewind, slow motion, fast forward, and so on. These systems also hinder the introduction of new forms of interactive media to be deployed.
• one popular approach to offer some form of VCR-liked interactivity over NVOD and QVOD systems is to add a storage unit to the set top box (STB) so as to cache all the available content being broadcast.
• STB set top box
• this invention provides, in the broad sense, a method and the corresponding system for transmitting data over a network to at least one client having a latency time to initiate transmission of said data to the client.
• the method of this invention includes the steps of: generating at least one of anti-latency data stream containing at least a leading portion of data for receipt by a client; and generating at least one interactive data stream containing at least a remaining portion of said data for the client to merge into after receiving at least a portion of an anti-latency data stream.
• the anti-latency data streams and the interactive data streams may be generated by at least one anti-latency signal generator and at least one interactive signal generator, respectively.
• the K data segments may be generated by a signal generator.
• This invention also provides a method and the corresponding system for transmitting data over a network to at least one client including the steps of generating a plurality of anti-latency data streams, in which the anti-latency data streams include: a leading data stream containing at least one leading segment of a leading portion of said data being repeated continuously within the leading data stream; and a plurality of finishing data streams, each ofthe finishing data streams:
• each successive finishing data stream is staggered by an anti-latency time interval.
• This invention further provides a method and the corresponding system for transmitting data over a network to at least one client.
• the method includes the steps of generating M anti-latency data streams from 1 to M, wherein an m th anti-latency data stream has F m segments, and F m is an m th Fibonacci number; and wherein said F m segments are repeated continuously within the m anti-latency data stream.
• the method includes the steps of generating M anti-latency data streams containing 1 to K anti-latency data segments, wherein the anti-latency data segments are distributed in the M anti-latency data streams such that an k ih leading segment is repeated by an anti-latency time interval ⁇ kT within the anti-latency data streams.
• This invention further provides a method for receiving data being transmitted over a network to at least one client.
• the data to be transmitted is fragmented into K segments each requiring a time T to transmit over the network.
• the data is divided into two batches of data streams, the anti-latency data streams include M anti-latency data streams, and the interactive data streams include N interactive data streams.
• the method for receiving the data includes the steps of: - raising a request for said data.
• the request may be raised by a processor ofthe client; and connecting the client to the M anti-latency data streams and receiving data in the M anti-latency data streams.
• the client or the receiver may connect to the anti-latency data streams by a connector.
• This invention also provides a method and a corresponding system for receiving data being transmitted over a network to at least one client, wherein said data includes a leading portion and a remaining portion, and the remaining portion is transmitted by at least one interactive data stream including the steps of: - pre-fetching the leading portion in the client as pre-fetched data, which is contained in the buffer ofthe client; and merging the pre-fetched data to the remaining portion by a processor.
• the anti-latency data streams can be generated upon request from the client.
• Figure 1 shows the data stream structure of a NVOD system.
• Figure 2 shows the data stream structure of a QVOD system.
• Figure 3 shows the overall system architecture ofthe data transmission system of this invention.
• Figure 4 shows the data streams arrangement of Configuration 1 of the data transmission system of this invention.
• Figure 5 shows the data streams arrangement of Configuration 2 of the data transmission system of this invention.
• Figure 6 shows the data streams arrangement of Configuration 3 of the data transmission system of this invention. Note the difference in the arrangement of the Group II data streams comparing with Figures 4 & 5.
• Figure 7 shows yet another Group I data streams arrangement of Configuration s.
• Figure 8 shows the data streams arrangement of Group I data streams of
• Figure 9 shows yet another arrangement of Group I data streams of Configuration 4 ofthe data transmission system of this invention.
• Figure 10 shows one ofthe data streams arrangement of Configuration 5 ofthe data transmission system of this invention.
• the particular arrangement of Group I data streams shown in this figure combines Configurations 1 & 3.
• Figure 11 shows the system configuration of a multicast data streams generator ofthe data transmission system of this invention.
• Figure 12 shows the system configuration of receiver of the data transmission system of this invention.
• Figure 13 shows the local storage versus transmission bandwidth trade-off relationship.
• Figure 14 shows an alternative "on-demand" approach of Configuration 1.
• Figure 15 shows an alternative "on-demand” approach of Configuration 2.
• Figure 16 shows an alternative "on-demand” approach of Configuration 3.
• this invention may be used for deploying an operating system software to a large number of clients through a network upon request. Further, this invention may be utilised in data transmission systems handling a large amount of data with repetitive content, for instance in a video system bus of a computer handling many complicated but replicated 3D objects. Moreover, this invention may not be limited to the transmission of digital data only.
• a multi-stream multicasting technique is used to overcome the existing problems in VOD systems as described in the Background section.
• the users are allowed VCR-liked interactivity without the need to add a storage unit at the STB and caching all the content that may be viewed by the user on a daily basis.
• FIG 3 shows the system configuration.
• the multicast streams are generated from a multicast server unit.
• the streams are multiplexed onto the physical media and distributed to the end users through a distribution network.
• a set top box such as DDVR, that selects a multitude of streams for processing.
• STB set top box
• the start-up latency may be mimmized while the users are provided with interactive functions.
• the DDVR should have sufficient bandwidth, buffer and processing capability to handle the multi-streams.
• the data transmission system of this invention which may be called an IVOD system, may look similar to the NVOD system.
• the IVOD and NVOD systems are differentiated by the following points:
• staggered used above and throughout the specification in describing the data streams refers to the situation that each ofthe data streams begins transmission at different times. Therefore, two “frames" of two adjacent data streams, in which the term “frame” represents the repeating unit of each data stream, are separated by a time interval.
• the data transmission method and system may be described as providing two groups of data streams Group I and II.
• Group I data streams which may be term anti-latency data streams, may serve to reduce latency for starting-up the transmission of the required data.
• Group I data streams may be generated by at least one anti-latency signal generator.
• Group II data streams which may be termed interactive data streams, may serve to provide the desired interactive functions to the users.
• Group II data streams may be generated by at least one interactive signal generator.
• For the interactive functions provide by Group II data streams this can be referred to the applicant's PCT applications nos. PCT/TB00/001857 & 1858, the contents of which are now incorporated as references therein. The operation of the interactive functions is not considered to be part of the invention in this application and the details will not be further described here.
• the content to be transmitted having a total amount of data Q requires a total time R to be transmitted over the network.
• the content for example, may be a movie.
• the Q data is broken up into K segments each having an amount of data S. Each data segment requires a time T to be transmitted over the network.
• Q and S may be in the unit of megabytes, while R and T are units of time.
• the data segments ofthe Q data are labelled from 1 to K
• the Q data may be divided into a leading portion
• the Group I anti-latency data streams may contain the leading portion only.
• the Group II interactive data streams may contain the remaining portion or the whole set of the Q data, and this may be a matter of design choice to be determined by the system manager.
• the system may still work if the individual data segment contains different amounts of data than each other, provided that they all required a time T for transmission. This may be achievable by controlling the transmission rate of the individual data segment.
• individual data segments may be preferred to have same amount of data S for the sake of engineering convenience.
• it may be relatively more difficult to implement the system for each of the data segments to have same amount of data S but with different transmission times.
• the following description refers to the transmission of one set of data, for instance, a movie, it should be apparent to one skilled in the art that the method and system may also be adapted to transmit a certain number of sets of data depending on, for example, the bandwidth available.
• Dual streaming means that each user will tap into at most two of the multicast data streams at any time. Most of the time, the user may only be tapping into one data stream.
• the segments are put onto the staggered streams as shown in Figure 4. There are two groups of staggered streams. For Group I anti-latency data streams, there are J segments on each frame. T is the anti-latency time interval and may also be the upper bound for the start-up latency of the IVOD system. Each anti-latency data stream is preferably staggered by the anti-latency time interval T, although the anti-latency time interval may be set at any desired value other than T.
• Jis equal to 16 and T is 30 seconds. So the frames in each of the Group I data streams repeat themselves after a time of JT being 8 minutes. There are a total of M streams in Group I.
• N interactive data streams there are N interactive data streams, with each of them being staggered by an interactive time interval.
• the interactive time interval may again be set at any desired value, the interactive time interval is preferably to be JT (i.e. 8 minutes in this example) for the sake of engineering convenience.
• the length ofthe content is R (say R equals to 120 p minutes)
• there should be at least a total of — 15 streams in Group II.
• N may
• the DDVR at the user end will select one stream from Group I (Stream li) and one stream from Group II (Stream IIj) to tap into.
• the client connects to Streams li and/or IIj, the data streams are processed by the DDVR, the client, and the segments are buffered according to the segment sequence number.
• the availability of the Group I staggered streams with stream interval T minimises the start-up latency to be equal to T.
• each Group II data streams may preferably contain only the remaining portion ofthe Q data.
• the method on merging of data streams can be found in the DMA technology. After merging, the Group I stream may no longer be needed and the DDVR may then rely solely on Stream IIj for subsequent viewing. This may be the optimised alternative only to minimise network load.
• the total number of streams in this type of IVOD system is M - ⁇ .
• the second example of IVOD system is also characterised by a dual-streaming operation. Again, the content is broken up into K segments of regular length T, and the segments are labelled from 1 to K respectively. The segments are put onto the staggered streams in a pattern as shown in Figure 5.
• Group I anti-latency data streams there are J segments on each frame and the frames are repeated on each stream.
• Jis again chosen to equal to 16 and Tis 30 seconds.
• This configuration characterises in that one of the Group I data streams, Stream II, contains only Segment 1 repeated in all time slots.
• Streams 12 to 19 contain Segment 2 to 17.
• Segment 1 may be viewed as a leading data stream containing the leading segment ofthe leading portion.
• Segments 2 to 9 may be considered as a plurality of finishing data streams containing the rest of the leading portion in the number of J segments.
• the Group I stream interval may be chosen to be any desired value, but is again preferably set to be T due to same reason as in Configuration 1.
• Streams 12 to 19 repeat themselves after JT (i.e. 8 minutes in this example).
• leading segment shown in Figure 5 contains only one leading segment, it should be understood that the leading data stream may contain more than one leading segment, for example, segments 1-4.
• the above conditions of the Group I anti-latency data streams of this Configuration 2 may then be viewed as T being four times as long, while this change may not affect the Group II interactive data streams. In such cases, the user may suffer from a larger start-up latency.
• M j may be substantially reduced and could be M - — + 1 for the smooth merging of the
• the arrangement and the set up of the streams may be the same as in the previous example, and the same setting and variations is also applicable to this application.
• the DDVR at the user end will immediately tap onto Stream II .
• the start-up latency should be bounded to T as the leading segment is repeated every time period T.
• the DDVR will also tap onto one of the Group I finishing data streams, 12 to 19 in this case.
• Stream li is chosen.
• the DDVR may tap onto the leading data stream and one of the finishing data streams simultaneously if the DDVR is capable of doing so. In the latter case, both streams are processed by the DDVR and the segments are buffered according to the segment sequence number.
• the DDVR will also tap onto one of the Group II streams (in this case Stream 112).
• the time at which the DDVR taps onto the Group II streams is a matter of choice - it may do so:
• the DDVR should tap onto one ofthe Group II streams at least right before all data in Group I streams is received or played by the client.
• the DDVR After all data in the Group I data streams has been buffered and received, the DDVR then merge onto one of the Group II streams.
• the merging technique is described in the DMA technology. After merging, the Group I stream (i.e. Stream li) may no longer be needed and the DDVR may rely only on the Group II stream for subsequent viewing to save bandwidth. Any allowable interactive request received at any time can be entertained as previously shown in the DMA technology.
• the total number of streams in this 1NOD system is (— + 1) + N . As N
• the optimal total number of data streams of the system is equal to
• the third example of INOD system is also characterised by a dual-streaming operation with the segments arranged in a hierarchical periodic frame structure with a size based on the Fibonacci numbers. Again, the content is broken up into K segments of regular length T, and the segments are labelled from 1 to N respectively. The segments are put onto the staggered streams in a pattern as shown in Figure 6. There are also two groups of staggered streams.
• Group I data streams contains the data in the leading portion having J segments. Note that this J is slightly different from those used in Configurations 1 and 2.
• the frame period is given by F m where F m is the m-th Fibonacci number.
• the first few Fibonacci numbers are shown in Table 2.
• the Group I stream interval is again preferably set to be T as in Configurations 1 and 2.
• the arrangement and the set up ofthe streams are similar to the previous examples, but for the sake of illustration, the Group II streams starting at Segment 81.
• Segment 3 will either be buffered during the time when Segment 2 is being received, or Segment 3 will be available on Stream 12 immediately following Segment 2's completion. After both Segments 2 and 3 have been received out, the DDVR will tap onto Streams 3 and 4, and the process continues as before. Both streams are processed by the DDVR and the extra segments are buffered according to the segment sequence number.
• the DDVR is presumed to connect to the 1 st and 2 nd data streams for starting-up the movie such that the latency is bounded to be T.
• the user may choose to first tap onto the m th and (m+l) th data streams, wherein m is any number larger than 1.
• the user can still view the content but may be suffering from larger latency. This may be preferred by some users who wish to skip the first few minutes of a movie, for example.
• each of the data segments shown in Figure 6 may contain more than one of the K segments of the data to be transmitted.
• each of the data blocks as shown in Figure 6 may in fact contains 5 data segments.
• the above conditions of the Group I anti-latency data streams of this Configuration 3 may then be viewed as T being five times as long, while this change may not affect the Group II interactive data streams. In such cases, the user may suffer from a larger start-up latency.
• m may not have to start from 1, provided that the users can accept a larger start-up latency and trimming of data.
• the system administration may remove the first four Group I data streams in Figure 6.
• this arrangement may not be allowed, otherwise the user may not be able to receive the complete software.
• this may be acceptable, provided that the trimming of the video is accepted by the copyright owner.
• the DDVR preferably begin to merge onto one of the Group II streams, at the very least to save bandwidth, once the number of segments buffered has exceeded the size of the Group II stream interval (in this case 80 segments are needed for an 8-minute Group II stream interval).
• the Group I stream i.e. Stream li
• the DDVR may rely only on the Group II stream for subsequent viewing. Any allowable interactive request received at any time can be entertained as described in the DMA technology.
• the number of Group I data stream required, M is determined by the number of Group II data streams, which is in turn to be determined manually according to various system factors. With a given start-up latency T, the total number of streams required in this INOD system can be found by looking up the necessary frame size from a table containing the relevant Fibonacci numbers. The minimal number of data
• N individual Group I data streams. may be less than this value but then the user may suffer from the phenomenon of "dropping frames".
• M may be larger than this value but this may create unnecessary network load. This may be a matter of design choice that should be left to be determined by the system administrator.
• the start-up latency T can be as low as 6 seconds (with an average of 3 sec), with a Group LT stream interval of 8 minutes.
• the total number of streams required for a 2-hour content can be as low as only 26.
• FIG. 8 shows a possible optimal arrangement of the initial thirty segments or so in various streams based on the harmonic series approach.
• the segments are labelled 1, 2, 3, ... etc...
• the necessary and sufficient condition for guaranteeing the start up latency to be bounded within one slot interval using only an optimal number of streams is that the placement of the segments should be done in such a way that Segment y (i.e. the - th segment from the beginning of the leading portion) should be repeated in every j time slots or less, for ally from 1 to J.
• Segment 1 should be repeated in every time slot in order that the start-up latency is bounded within one anti-latency interval T.
• Segment 1 there may be a whole stream taken up by Segment 1 alone.
• Segment 2 should be repeated in every other time slot in order that the second segment is available immediately after the first segment has been received.
• Segment 3 should be repeated in every three time slots and Segment j should be repeated in every / time slots.
• the segment j may be repeated more frequently than required. That is, the/ segment is repeated by an anti-latency time interval ⁇ jT . Note that the definition of the term "anti-latency time interval" in this Configuration 4 is different from that in Configurations 1 to 3.
• the exact stream where the segments are placed does not matter as we are assuming that all streams are being received and processed by the DDVR.
• the segments are buffered by the DDVR and rearranged into a suitable order.
• the unfilled slots in Figure 9 can contain any data or even be left unfilled.
• J can be set to any desired number larger than — , for the sake of engineering
• J which equals to the number of data
• Figure 8 may contain more than one of the K segments of the data to be transmitted.
• each of the data blocks as shown in Figure 8 may in fact contains 10 data segments.
• the above conditions of the Group I anti-latency data streams of this Configuration 4 may then be viewed as T being ten times as long, while this change may not affect the Group II interactive data streams. In such cases, the user may suffer from a larger start-up latency.
• j may not have to start from 1 but any number larger than 1, provided that the users can accept a larger start-up latency.
• the system administration may remove the first three Group I data streams in Figure 8.
• this arrangement may not be allowed, otherwise the user may not be able to receive the complete software.
• this may be acceptable, provided that the trimming of the video is accepted by the copyright owner.
• j may start from any number larger than 1, for example, 5.
• the streams are again divided into two groups, Groups I and II.
• the segment arrangements of the Group I streams has been shown in Figure 8.
• the segment arrangements ofthe Group II streams are same as those shown in any one of Figures 4 to 6.
• a suitable Group II stream will also be tapped into and processed. This allows a smooth merging of the Group I streams (where the initial m segments are placed) into a single Group II stream.
• the tapping onto the Group II stream may await until all data in the leading portion contained in Group I streams is received by the client DDVR.
• All the Group I streams may no. longer be needed and only a single Group II stream is needed for the continuous viewing by the user.
• the user could initiate any of the allowable interactive requests, including pause and resume, rewind, and slow motion playback.
• this multi-streaming arrangement may be used to replace the Fibonacci stream sequences (Group I streams) in Configuration 4 to further reduce the number of streams required.
• the condition is that the DDVR should have enough buffer and processing power to buffer and process the received data.
• Table 3 in the up-coming section lists some results in all various configurations.
• Configurations 3 and 4 demonstrate an IVOD system with a very short start-up latency in comparison with Configurations 1 and 2 using a comparable numbers of streams. But Configuration 1 or 2 also has an advantage over Configuration 3 or 4 - they allow coarse jumping from stream to stream during the first stream interval while Configuration 3 or 4 does not. In real life, the first few minutes of a content source usually contain a lot of header and information that many users may want to skip by jumping. Therefore, it is desirable to provide at least a limited jump capability for the users.
• This INOD system contains three groups of staggered streams, namely, Group 1(1) and 1(2).
• Group 1(1) data streams has a total number of A data streams responsible for distributing data having C segments.
• Group 1(2) data streams has a total number of B data streams responsible for distributing data having D segments, with each of the B data streams being staggered by a coarse jump interval. There are E data segments in the coarse jump interval.
• Group 1(1) contain the first 7 Fibonacci streams as shown in Configuration 3.
• Group 1(2) contain the 8 Group I streams as shown in Configuration 1 mrn ing from Segment 11 to 90, with a staggered stream interval of 10 segments.
• Group 1(2) can contain data segments running from 1 to 90, although it may seem to be redundant.
• the frame period of Group 1(2) streams is 80 segments or 8 minutes, and this is the coarserjump frame period allowing the user to perform a coarse-jump interactive when the DDVR is connecting to the Group I data streams.
• Group II streams of Configuration 5 are identical to the Group II streams of the other configurations. In this particular example, each of the Group II streams starts from Segment 1 and going all the way to the end of the entire content. The arrangement of the streams and segments are shown in Figure 10.
• the user can start at any time with a start-up latency of one segment (6 seconds in this example). Furthermore, users can coarse jump at any time within the start-up period, the time when the DDVR connects to the Group I streams.
• the start-up period is preferably defined to be the time within the first Group II stream interval (that is, from the 0-minute point to the 9-minute point) as in previous configurations. Each coarse jump is 1 minute apart from each other, which is determined by the coarse-jump frame period. Thus, the users can skip the headers using this arrangement.
• the total number of streams needed for holding a two-hour content in the particular example shown in Figure 10 is 30.
• the number of Group 1(1) data streams required i.e. A, may be determined by
• Configuration 4 is used, then As m Configuration 4, C, the total number of data segments to be transmitted in Group 1(1), preferably equals to E. The same considerations on the number of data streams required as in Configurations 3 and 4 may also be applicable to Group 1(1).
• the anti-latency data streams as described above may be preferred to be generated continuously such that these streams present in the system continuously, or at least during the prime time (let say, 6-11pm), for users to tap into.
• the prime time let say, 6-11pm
• some further bandwidth may be saved if the anti- latency data streams are generated upon request of the users.
• This alternative approach may be beneficial to Configurations 1, 2, and 3. These are shown in Figures 14, 15, and 16. In these figures, the data segments in grey represent those data segments or data streams that are "turned-on" upon requests from the users.
• each of the Group I anti-latency data streams is still staggered by an anti-latency stream interval T.
• not all of the Group I anti-latency data streams may present or "turned on” at all times.
• the anti- latency data streams can be terminated to further minimize the bandwidth usage.
• Configuration 4 As one of the basic requirements in Configuration 4 is that the user should be able to be connected to all of the Group I data streams, this "on-demand" approach does not appear to be applicable to Configuration 4.
• this alternative approach may seem to save some additional bandwidth in comparison with the original Configurations, they may be less preferred due to several reasons. First, it may increase the workload and the processing requirement on the server side, and the complexity in programming and implementation. Second, this may lead to the overload ofthe resulting system if care is not taken at the design stage in allocating the required bandwidth. Third, this alternative approach will in fact become the original Configurations when the number of requests from the user is large.
• each data segment which can be termed the head portion, may contain duplicated data appearing in the tail portion of the immediate preceding segment.
• the amount of data to be carried in the duplicated portion may be T' (normalized with respect to the data rate ofthe stream), where T' is the delay that may incur during the change over of the streams.
• T' may be in the order of 10 - 20 milliseconds.
• the server needs to generate the appropriate multi-streams in patterns that have been illustrated in any one of Configurations 1 to 5 or such patters as may be designed.
• the distribution network should have sufficient capacity to carry all the required streams to the end user DDVR.
• the end user DDVR should have sufficient bandwidth, buffer and processing capability to handle the multi-streams.
• the DDVR should also have sufficient storage to buffer at least one Group II stream interval of data from the multi-streams.
• the receiver DDVR may have a processor for raising request for the content, and a connector for connecting the Group I and II data streams.
• the DDVR For Configurations 1 and 2, it may be necessary for the DDVR to include a buffer for buffering the received Group I data streams. For Configurations 3 and 4, the DDVR should include a buffer for buffering the data received from Group I data streams. The processor will then also be responsible for processing the data to put the data in a proper order.
• the receiving device, the receiver, at the user end may not need to have any hard disk storage.
• the only memory or buffer needed at the STB, the client/receiver, may be the RAM (random-access memory) to buffer one stream interval equivalent of data. Assuming a stream interval of 8 minutes, this requires roughly 60 MB of RAM for a 1 Mb/s MPEG-4 stream.
• This technique can be contrasted with many NOD techniques that require a large hard disk storage (sometimes as large as 60 GB) at the STB. Therefore, this TvOD system also appears to the users like a diskless DVR.
• the system provider may choose to provide addition storage to the users in the form of hard disk or other non- volatile medium or use such other equipment as may be necessary to buffer and receive the data.
• the DDVR may be configured such that it plays the received data at a slower rate than the transmission rate of the data.
• the transmission rate may be
• the DDVR may be required to have a larger buffer size to accommodate the un-received data.
• the DDVR may be configured to contain or pre-fetch at least a portion of the data in the Group I data streams, i.e. the leading portion of the data to be transmitted, for a certain period of time in its local buffer.
• data may be termed "pre-fetched data”.
• the pre-fetched data may contain all of the data contained in the Group I data streams provided that the DDVR has adequate buffer size.
• the content ofthe data to be transmitted may be refreshed every day for video data, or more than once per day. In this particular example, it may be necessary for the pre-fetched data to be refreshed every day.
• the refresh time may be set at any desired value that may range from one day to even one year.
• This process may be initiated by the anti-latency signal generator, the interactive signal generator, or by the client itself by a routine call procedure. In doing so, the latency time and the total number of data streams required in the network may be further reduced. This may be particularly important for VOD systems transmitting a large number of sets of data.
• Vertex 1 maybe realised as current VOD systems with all the data being sent and then stored in the STB, whether the client raises a request for the data or not. In such a case, the STB should have a relatively large buffer size. This may increase the manufacturing costs ofthe STB.
• Vertex 2 may represent the systems as described in Configurations 1-5. Under such a configuration, the requirement on the STB may be minimal while the system may be more demanding on the bandwidth.
• Vertex 3 may represent a hybrid system of Vertexes 1 and 2.
• the IVOD systems of this invention may find immediate applications in existing cable TV, terrestrial broadcasting, and satellite broadcasting systems. With very little modification on the existing infrastructure, the non-interactive broadcasting, or NVOD systems may be converted into an IVOD system. Both analogue and digital transmission systems can take advantage of the multi-streaming concept. However, the discussions below will only describe system configurations for digital transmission systems.
• the RF transmission bands are usually divided into 6 MHz (NTSC) or 8 MHz (PAL) channels.
• NTSC 6 MHz
• PAL 8 MHz
• FIG 11 shows a typical system configuration for this multi-streaming system. It is very similar to existing broadcasting system. Only the transmission unit at the head end, which may be called an anti-latency device, and reception unit at the user end, the client/receiver, may need to be modified.
• digital signals such as QAM are transmitted.
• the set top box should be RF-tuned to the particular RF channel of interest.
• the cable modem would filter out the 30 - 40 Mb/s digital streams and decode two streams at a time (for Fibonacci dual-streaming systems) or decode all the harmonic multi-streams (for harmonic multi-streaming systems).
• Figure 12 shows the block diagram of the STB / cable modem.
• the STB / cable modem is similar to other STB / cable modems except for its processing unit which can process at least 2 multi-streams simultaneously rather than a single stream.
• the decoded streams would be buffered in the STB and the content would be reconstructed according to the sequence number of the segments. With the hundreds of channels available in a typical broadcasting system, this translates to over 200 hours or more of fully interactive programs available to an infinite number of users.

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