British Telecommunications Public Limited Company

British Telecommunications Corporation

Matthew D Walker

Rory Stewart Turnbull

Simon P A Ringland

Philip L Eardley

Richard J Jacobs

Nicholas J Sim

Michael Erling Nilsson

Benjamin Bappu

Roberto Alvarez Arevalo

Othon Kamariotis

Dimitrios Miras

Eduardo Urzaiz

Richard I M Jeffery

A system for transmitting data via a core portion of a computer network to a mobile device is described. The network includes a plurality of access points wherein each access point includes a memory where data for onward transmission to the mobile device may be cached and is operable to communicate with the mobile device over a short-range wireless connection, when the mobile device is in range thereof, and with the core portion of the network over a backhaul connection on a substantially continuous basis. The exemplary system includes: a location collection server for receiving location data from the mobile device; an access point prediction engine for generating predictions of one or more of the access points which the mobile device is considered likely to come in range of in the future based on recent location data received at the location collection server; and a content delivery server for transmitting the data or a portion thereof to the one or more predicted access points via the backhaul connection for caching at the access points and for onward transmission to the mobile device in the event that the mobile device comes into range of the access point, or one or more of the access points where data is transmitted to more than one predicted access point.

Method of transmitting data to a mobile device

A method of call control in which a first communications network, detecting calls directed to a destination in the first network; redirects at least some of the calls to a destination in a second network (e.g. on no answer from the destination in the first network). The first communications network obtains from a client on a terminal associated with the destination in the second network a value for the time delay before a call to the destination in the second network is redirected in the second network on no answer to an alternative destination and sets a delay period to a value less than the value of the time delay obtained from the client. When one of the plurality of calls redirected to the second network is not answered in the second network within the delay period, the first communications network redirects the call to an alternative destination associated with the first network.

Call control

A method of intelligently degrading the quality of content, such as video clips and music, stored on a mobile device over time. The method takes into account the probability of a user watching each item of content and either encodes the content at a lower bit-rate, or under certain circumstances, restores the content to its original quality by side-loading the content from a network content store. The bit-rate at which the content is to be encoded is linked to the probability of a piece of content being watched. If the probability of an item of content being watched is high, then the item is stored at a high bit-rate, and conversely, for low probabilities of watching, a low bit-rate is used. If required, in order to restore an item to a higher bit rate, the original high bit rate item can be requested from a network content store. The aim being to store as much content as possible in a given finite memory, but to ensure that content which is likely to be watched is not degraded.

Device content management

A method of call control in which a first communications network, detecting calls directed to a destination in the first network; redirects at least some of the calls to a destination in a second network (e.g. on no answer from the destination in the first network). The first network then operates in two phases. In a first phase, for a group of calls redirected to the second network, the time delay before the call is answered in the second network is recorded. When a number of time delays have been recorded, a delay period is set to a value less than the maximum value of the recorded time delays. In a second phase, for a second group of calls redirected to the second network subsequent to the calls of the first group, when a call of the second group is not answered in the second network within the delay period, the call is redirected to a message service associated with the first network.

There is proposed a method of side-loading content onto a mobile device, preferably using a WiFi connection, from a network content store and storing it on the device for viewing later. The method automatically determines when to delete stored content, and more importantly, what content should be transferred over the network in the first instance. The system comprises a content manager which takes into account various parameters to determine what should be transferred and, if required, what should be deleted from the device. The parameters used include user profiles, size of a potential download, as well as available storage space on the device and the predicted duration the device will be in range of a wireless hotspot or broadcast network.

Data management

A client on a packet based network is provided with a stream of encoded video data. The system is maximizes the bit-rate of the video stream by adapting to fluctuations in network capacity. Adaptation of the bit-rate of the transmitted enclosed video data is timed to occur upon a scene change in the video sequence. In this way the interruption to the viewer when the perceived quality of the video sequence increases or decreases is minimized as it is 'hidden' in the scene change. The technique may be applied to hierarchically encoded video data and to other encoding technique which adapt to network conditions.

Video stream switching

Real-time data (e.g. video) is streamed over packet networks (e.g. the Internet). Streamed video is provided without the start-up delay by transmitting data from a video streamer to the video viewer more rapidly than the video viewer consumes the data and using the excess data to build a buffer at the video viewer. When a suitable sized buffer is built the transmission rate of data to the buffer may be reduced. In order to deliver the best quality material for the available bandwidth, the supply of video data may be switched to a higher bit-rate source when the reservoir is filled. Fluctuations in network throughput may be accommodated during the transmission of data on a fine scale by adjusting the transmission rate of the data and on a coarse scale by switching between data streams encoded at different bit-rates. Fluctuations in network throughput are determined by counting the number of missing packets at the video viewer which information may then be fed back to the video streamer to adjust the flow of data accordingly.

Transmitting and receiving real-time data

Data for presentation in real time, such as a video or audio sequence, is available on different encoded versions having different degrees Of compression. In order to assess, during transmission of one version, the feasibility of switching to another version, given the data rate known to be available at the time, a server computes, for a candidate version, in respect of at least one portion thereof that has not yet been sent, the maximum value of a timing error that would occur if any number of portions starting with that portion to be sent at the available rate. The selection of the same or a different version for continuing transmission is taken in dependence on a comparison between the computed error and the current state of a receiving buffer. Error values may be computed in advance for a range of transmitting rates, stored and later retrieved for use in estimating an error value corresponding to the actual transmitting rate.

Transmitting over a network

Data to be transmitted over a network includes a first part (perhaps audio) which is always to be transmitted and alternative second parts (perhaps video coded at different compression rates) of which one is to be chosen for transmission, depending on the current network capacity. In order to accommodate systems where (owing perhaps to the use of a congestion control mechanism such as TCP) the capacity available is initially undetermined, one firstly begins to transmit just the first part. When the network capacity becomes known (typically by monitoring the performance of the network in transmitting the first part), one of the alternative second parts is chosen and transmission of it commences. If desired this may initially be preferentially to, or to the exclusion of, further transmission of the first part.

Data transmission

A preferred data provider is selected from a plurality of data providers by receiving a request for data from a client together with client identification data, identifying a plurality of data providers capable of providing data to the client, providing the client identification data to the data providers and instructing the data providers to perform tests in order to establish a measure of the elapsed time for a signal to be sent to and received from the client, and a measure indicative of their remaining capacity for data transfer, and to make these measures available to the system. One or more preferred data providers may then be selected on the basis of the elapsed time signals and the remaining capacity signals from the data providers.

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Felixstowe, United Kingdom

Matthew D Walker