Abstract: A method of managing a network for delivering content to a client device, where content segments are delivered over multicast to a proxy. The received segments are stored at the proxy, before delivery of those segments is made from the proxy to the client device over unicast. Whilst the proxy receives further segments over multicast, it probes the network by making unicast requests for data (dummy data or additional content segments), and receiving those segments over unicast from the content server. The multicast rate reception rate and the unicast (probe) rate are measured and a maximum network throughput is calculated as the sum of these two rates. Subsequent segments are then delivered from the proxy to the client device at the calculated maximum network throughput rate, or at some rate dependent thereon.

Abstract: Described is a method of managing a network for delivering content in a hybrid unicast/multicast network, where content is requested by clients over unicast, but all or some of the content is delivered in part over multicast. Typically, a client requests content (in the form of segments) via a first proxy. The segments are delivered to the first proxy over multicast from a second proxy, before onward transmission to the requesting client over unicast. The segments are also cached at the first proxy, and can be transmitted over unicast to other clients requesting those segments. However, problems can arise if cached segments are transmitted to clients too quickly. In one solution, the first proxy measures the multicast rate of delivery of segments from the second proxy over multicast, and limits the transmission rate of those segments over unicast to requesting clients to no greater than the measured multicast delivery rate.

Abstract: Described is a method of delivering content over a network using an approach referred to as “Multicast Assisted Unicast Delivery” (MAUD), as a multicast network is used to assist, rather than substituting for, an otherwise unicast path. Content is requested by client devices from a content server over unicast. The responses containing the requested content are separated into two components: a first component containing elements that are specific to individual client devices (for example session specific data), and a second component that is common to all client devices (typically this is the video content being requested). The first component can be delivered over unicast and the second component over multicast. Identifiers are introduced into each of the first and second components to aid recombination of the components to form the original responses. The separation and recombination are handled by suitably configured proxy servers.

Abstract: Described is a method of delivery of content to a client device. In particular, the method can be applied to hybrid unicast/multicast delivery networks, where content is provided by a content server to a root proxy, and that root proxy delivers the content to edge proxies over multicast. However, requests for that content in the form of HTTP GET requests from a client device are received by an edge proxy, which subsequently sends an HTTP HEAD request for header information associated with that content directly to the content server. The content server responds over unicast with a suitable response to the HTTP HEAD request, which is received by the edge proxy. The edge proxy takes the response together with the payload from the content segment received over multicast, to generate a client specific content segment for delivery to the client device over unicast.

Abstract: A method of delivering a video sequence in a network, the sequence including a plurality of temporal segments encoded at a plurality of qualities, the method including storing a dataset indicating the relative size of segments of the video stream; computing in dependence on that dataset a time schedule for delivery of the segments, the time schedule indicating a target delivery time for each segment sufficient to deliver all the segments in the sequence in time for decoding and being independent of the encoded quality of each segment; for each segment: setting one or more transmission parameters for the segment in dependence on the target delivery time for the segment and the relative size of the segment; and delivering the segment over the network using the one or more transmission parameters.

Abstract: Described is a method of managing a network for delivering content in a hybrid unicast/multicast network, where content is requested by clients over unicast, but all or some of the content is delivered in part over multicast. A client requests content (in the form of segments) and receive the responses (segments) over unicast via a first proxy. The first proxy measures the time between requests and associated requested segment sizes. These measurements are used to effectively determine a unicast request rate given by the segment size divided by the time between requests. Subsequent requested segments can then be delivered over multicast over a portion of the route to the client using a multicast rate that is set as a function of (for example, 110% of) the unicast request rate. In general, the multicast path will be from a second proxy to the first proxy.

Abstract: In examples of the present invention, during delivery of content, the round trip times for each delivered data packet are measured and the congestion window used for delivery is adjusted accordingly. The congestion window is set to a relatively high value when the round trip times are relatively low, and set to a relatively low value when the round trip times are relatively high.

Abstract: A method of determining the bandwidth of a link carrying a plurality of data streams between a plurality of sources and a plurality of destinations in a network, the method including sending data packets from a first data stream over the link from one source to one destination at a first transmission rate, and measuring an associated first packet loss rate; sending further data packets from the first data stream over the link from the one source to the one destination at a second transmission rate, and measuring an associated second packet loss rate; and determining the bandwidth of the link in dependence on the first and second packet loss rates and the first and second transmission rates.

Abstract: A method of delivering media content over a network, the media content including a plurality of temporal segments, wherein each temporal segment comprises a plurality of data packets, the method including: selecting an initial size of a first congestion window; delivering the plurality of data packets of a first segment using the first congestion window, the initial size of the first congestion window being used to control the size of the first congestion window for the duration of the first segment delivery; measuring the packet loss during the delivery of the first segment; determining an initial size of a second congestion window in dependence on the measured packet loss for the first segment; and delivering a second segment using the second congestion window, the initial size of the second congestion window being used to control the size of the second congestion window for the duration of the second segment delivery.

Abstract: In examples of the present invention, delivery of a segment of content is done using an initial congestion window, preferably chosen to give a delivery rate that ensures timely delivery of that segment. However, under high levels of packet loss, the delivery rate may not be sufficient. Hence, at any stage during delivery of a segment, the actual delivery rate is measured, and used, together with the previous congestion window size, the amount of content segment data still to be delivered, and the time left for delivery, to calculate an updated congestion window. The remainder of the segment is then delivered using this revised congestion window.

Abstract: A method of delivering media content over a network, the media content including a plurality of temporal segments, wherein each temporal segment comprises a plurality of data packets, the method including: selecting an initial size of a first congestion window; delivering the plurality of data packets of a first segment using the first congestion window, the initial size of the first congestion window being used to control the size of the first congestion window for the duration of the first segment delivery; measuring the packet loss during the delivery of the first segment; determining an initial size of a second congestion window in dependence on the measured packet loss for the first segment; and delivering a second segment using the second congestion window, the initial size of the second congestion window being used to control the size of the second congestion window for the duration of the second segment delivery.

Abstract: Examples of the present invention provide a method of converting a multicast stream into unicast segments. In particular, sequence identifiers are generated based on a clock reference field in the transport stream packets that make up the multicast stream. Every time a new sequence identifier is calculated, a new unicast segment is generated and assigned with the new sequence identifier. Transport stream packets are placed into the new segment until a packet is processed that causes a new sequence identifier to be generated, at which point another new segment is generated and packets placed into that segment. In an improved method, random access indicators in the transports stream packets are used to further constrain when a new segment is generated, to ensure that new segments are coincident with a packet having a random access indicator. This improvement makes random access easier back and forth between and within a stream.

Abstract: The invention presents a method of providing feedback for receipt of a multicast video stream. The feedback mechanism allows the number of clients receiving over multicast to be determined, which can then be used to manage multicast delivery, including switching decisions between multicast and unicast. Video content is delivered over a multicast stream from a content server to a plurality of client devices. The client devices are each configured to respond at regular intervals whilst receiving the multicast video stream by transmitting an HTTP HEAD request message to the content server. The HTTP HEAD request refers to metadata relating to a manifest file associated with the video stream. The number of client devices receiving the multicast video stream is determined based on the number of HEAD requests received at the content server.

Abstract: A method of delivering media content over a network, the media content including a plurality of temporal segments, wherein each temporal segment comprises a plurality of data packets, the method including: selecting an initial size of a first congestion window; delivering the plurality of data packets of a first segment using the first congestion window, the initial size of the first congestion window being used to control the size of the first congestion window for the duration of the first segment delivery; measuring the packet loss during the delivery of the first segment; determining an initial size of a second congestion window in dependence on the measured packet loss for the first segment; and delivering a second segment using the second congestion window, the initial size of the second congestion window being used to control the size of the second congestion window for the duration of the second segment delivery.

Abstract: A method of determining the bandwidth of a link carrying a plurality of data streams between a plurality of sources and a plurality of destinations in a network, the method including sending data packets from a first data stream over the link from one source to one destination at a first transmission rate, and measuring an associated first packet loss rate; sending further data packets from the first data stream over the link from the one source to the one destination at a second transmission rate, and measuring an associated second packet loss rate; and determining the bandwidth of the link in dependence on the first and second packet loss rates and the first and second transmission rates.

Abstract: A method of delivering a video sequence in a network, the sequence including a plurality of temporal segments encoded at a plurality of qualities, the method including storing a dataset indicating the relative size of segments of the video stream; computing in dependence on that dataset a time schedule for delivery of the segments, the time schedule indicating a target delivery time for each segment sufficient to deliver all the segments in the sequence in time for decoding and being independent of the encoded quality of each segment; for each segment: setting one or more transmission parameters for the segment in dependence on the target delivery time for the segment and the relative size of the segment; and delivering the segment over the network using the one or more transmission parameters.

Abstract: A method of grammar rule induction comprises obtaining a monolingual set of phrases from a bilingual corpus of translation pairs. For each of the monolingual phrases in turn, initialising, with inactive edges formed from headwords identified in the phrase, the agenda of a dependency grammar chart parser arranged to form packed edges in the chart. Running the chart parser and adding to the agenda, for each inactive edge removed from the agenda, one or more active edges created as if all possible grammar rules existed. When the agenda is empty, ascertaining the alternations of each edge in the packed edge corresponding to the complete phrase, and finding their respective highest frequencies. For the set of phrases, summing, for each alternation, its respective highest frequencies, and ranking the sums.

Abstract: A computer natural language translation system, comprising: means for inputting source language text; means for outputting target language text; transfer means for generating said target language text from said source language text using stored translation data generated from examples of source and corresponding target language texts, in which said stored translation data comprises a plurality of translation units each consisting of an aligned language unit (e.g. word). This invention generates the translation units for the translation system from a new source-target translation pair of examples, by generating source and target analyses and then finding the alignments by scoring and matching.

Abstract: A computer natural language translation system, comprising: means for inputting source language text; means for outputting target language text; transfer means for generating said target language text from said source language text using stored translation data generated from examples of source and corresponding target language texts, in which said stored translation data comprises a plurality of translation units each consisting of an aligned language unit (e.g. word). This invention generates the translation units for the translation system from a new source-target translation pair of examples, by generating an analysis of one of the texts, then finding, using a wildcard substitution process, a language unit which can be modified to generate a new language unit making the system able to translate the texts.

Abstract: A computer natural language translation system, comprising: means for inputting source language text; means for outputting target language text; transfer means for generating said target language text from said source language text using stored translation data generated from examples of source and corresponding target language texts, characterised in that said stored translation data comprises a plurality of translation components, each comprising: surface data representative of the order of occurrence of language units in said component; dependency data related to the semantic relationship between language units in said component; and link data linking dependency data of language components of said source language with corresponding dependency data of language components of said target language, and in that said transfer means is arranged to used said surface data of said source language in analysing the source language text, and said surface data of said target language in generating said target language t