Method and apparatus for time synchronisation in wireless networks
AssigneeImagination Technologies Limited
InventorIan R. Knowles
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Abstract
A wireless media distribution system is provided comprising an access point (6) for broadcasting media and a plurality of stations (2) for reception and playback of media. Each station is configured for receiving and decoding a timestamp in a beacon frame transmitted repeatedly from the access point. This is used to control the output signal of a station physical layer clock (12) which is then used as a clock source for an application layer time synchronisation protocol. This application layer time synchronisation protocol can then be used in the station to control an operating system clock (8) for regulating playback of media.
Claims19
A physical layer clock, comprising:
- a counter configured to increment in dependence on a clocking signal, wherein the physical layer clock is configured to:
- receive a timestamp value,
- determine an error between a current counter value and the received timestamp value,
- adjust the clocking signal in dependence on the determined error, and
- provide the adjusted clocking signal to the counter,
- wherein the counter is configured to be overwritten with the received timestamp value.
A method for synchronising a physical layer clock of a wireless station to a physical layer clock of an access point, the method comprising:
- receiving at the physical layer clock of the wireless station a timestamp value;
- incrementing a counter in dependence on a clocking signal;
- determining an error between a current counter value and the received timestamp value;
- overwriting the counter with the received timestamp value, and
- adjusting the clocking signal in dependence on the determined error;
- and
- providing the adjusted clocking signal to the counter.
Dependencies are inferred from the claim text.