Cambridge Silicon Radio Limited

Timothy Condren Smith

Peter William Stephenson

Andrei Popescu

A system for transmitting data between a first device and a second device, the first device being arranged to transmit data to the second device and the second device being arranged to transmit an acknowledgement to the first device if the data transmitted by the first device is properly received by the second device; wherein the system comprises means to measure the quality of reception of acknowledgements by the first device and to modify one or more acknowledgement transmission parameters depending on the measurement. The parameters may include: transmission rate, degree of forward error correction coding, and output power. The parameters may be modified to improve the quality of reception of acknowledgements if the measured quality falls below a threshold. The means to measure the quality of reception may comprise means to determine a measure of the number, or relative number, of acknowledgements that were not properly received by the first device. In an embodiment the first device is arranged to retransmit the data if an acknowledgement is not properly received, and the means to determine a measure of the number of acknowledgements that were not properly received by the first device comprises means to determine the number of data packets that have been received by the second device which were previously properly received by the second device.

Data transmission

Methods and apparatus for providing a flow control mechanism in a wireless network are described. In order to force a transmitting station to implement a rate adaptation mechanism, in which speed is traded off for reliability, a receiver within a receiving station behaves as if the radio conditions were degraded. This may be implemented when defined criteria are met, such as when the available buffer space falls below a threshold, and for some or all types of frames. In an embodiment, when the criteria are met, the receiver does not acknowledge frames received at one or more higher data rates.

Receiver which mimics degraded radio conditions when buffer overflow conditions are met

A method for transmitting data over a network in which multiple transmission conditions can be used for transmitting data, the method comprising selecting a transmission condition to be used when transmitting data over the network, said selection being made in dependence on a predetermined preference distribution that for each of the multiple transmission conditions defines a probability of that transmission condition being selected, using the selected transmission condition when transmitting data over the network and determining the success of the transmission and updating the preference distribution in dependence on the success of the transmission and thereafter selecting a transmission condition for transmitting data over the network in dependence on the updated preference distribution.

Transmission rate selection

A method for transmitting data over a network in which multiple transmission conditions can be used for transmitting data, each transmission condition being associated with a rating indicative of how successful previous data transmissions using that transmission condition have been, the method comprising using a selected transmission condition when transmitting data over the network and updating the rating associated with the selected transmission condition in dependence on the success of that transmission, updating the ratings associated with the transmission conditions other than the selected transmission condition by adjusting each of those ratings by a predetermined amount and selecting a transmission condition in dependence on the updated ratings.

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Cambridge, United Kingdom

Timothy Condren Smith