Abstract: A method of managing content delivery to a client device by a proxy, where the content is made up of a sequence of segments. The proxy starts off by receiving content requests from the client device over unicast, and fulfilling those requests by forwarding them to a content server, and receiving that content over unicast before forwarding onto the client device. The proxy then determines that a multicast channel should be joined to more efficiently receive the content. However, the multicast channel is likely to be ahead of the available unicast data. Therefore, a multicast join command is delayed until the proxy has taken steps to obtain subsequent content by unicast faster than that content is being requested by the client device, so that the obtained content has caught up with the content available on the multicast channel.

Abstract: A method of managing content delivery to a client device via a proxy is described. The proxy starts off by receiving content requests from the client device over unicast, and fulfils those requests by forwarding them to a content server, and receiving that content before forwarding onto the client device. The proxy then determines that it may be possible to join a multicast channel to more efficiently receive the required content. However, before joining the multicast channel, the proxy determines whether joining the multicast channel might result in the client device receiving content in a manner that would cause the client device to change the quality level of the content segments being requested. The proxy can do this by first obtaining segment requested by the client device from the unicast server over unicast. The proxy also requests timing information from the multicast server to determine a time at which the same segment will complete delivery over multicast.

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: A method of managing content delivery to a client device via a proxy is described. The proxy starts off by receiving content requests from the client device over unicast, and fulfils those requests by forwarding them to a content server, and receiving that content before forwarding onto the client device. At some stage, the proxy determines that it may be possible to join a multicast channel to more efficiently receive the required content. However, before a switch is made, the proxy gathers multicast delivery timing data from the content server without joining the multicast group, and behavioural characteristics of the client device. The proxy uses this data to determine whether the client device would change the quality level of the content segments being requested.

Abstract: A method of managing content delivery to a client device by a proxy, where the content is made up of a sequence of segments. The proxy starts off by receiving content requests from the client device over unicast, and fulfilling those requests by forwarding them to a content server, and receiving that content before forwarding onto the client device. At some stage, the proxy determines that a multicast channel should be joined to more efficiently receive the required content. However, the multicast channel is likely to be ahead of the available unicast data. Therefore, a multicast join command is delayed until the proxy has taken steps to obtain subsequent content by unicast faster than that content is being requested by the client device, so that the obtained content has caught up with the content available on the multicast channel. The proxy stores this content and uses it to respond to requests from the client device. Only then does the proxy take action to join the multicast channel.

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: 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 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 managing a network for delivering content to a client device, where content segments are delivered to a proxy in a multicast group, before delivery from the proxy to the client device over unicast. The proxy intermittently leaves the multicast group to probe the network by making unicast request for content segments, receiving those segments over unicast from the content server and forwarding those segments onto the client device. This allows the client device to determine the maximum throughput between the content server and the client device via the proxy, and thus the client device can use its adaptive bit rate algorithms to determine if the network can support a switch to a higher bit rate stream, and request a higher bit rate stream accordingly. The higher bit rate stream can be serviced by the proxy joining or establishing a suitable multicast group.

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 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: 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: 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 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: 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 delivering content over network using an approach referred to here 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. These unicast requests are sent via a first and a second proxy, before being sent by the second proxy to the content server, all over unicast. The responses containing the requested content is sent back to the second proxy over unicast from the content server. The second proxy processes the received unicast responses and sends the responses over a multicast stream to the first proxy. The first proxy processes the received responses and sends them onto the requesting client devices over unicast.

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.