British Telecommunications Public Limited Company

Timothy Stevens

Rory Stewart Turnbull

Stephen Clifford Appleby

Andrew Wills

Ivan Roper

Philip Coackley

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.

Content delivery

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. Thus, the client device will receive segments at a rate that is more indicative of the actual maximum network throughput, so can better use its adaptive bit rate algorithms to determine whether a switch to higher bit rate segments is appropriate.

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.

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London, United Kingdom

Timothy Stevens