Media time based USB frame counter synchronization for Wi-Fi serial bus

Patent metadata

Field	Value
Publication number	US-9830298-B2
Application number	US-201414270124-A
Country	US
Kind code	B2
Filing date	May 5, 2014
Priority date	May 15, 2013
Publication date	Nov 28, 2017
Grant date	Nov 28, 2017

Abstract

A method of transmitting universal serial bus (USB) frames over a communications channel is disclosed. A USB device receives one or more USB frames from a host device via a network, wherein the one or more USB frames are encapsulated in one or more data packets based on a communications protocol associated with the network. The USB device further synchronizes a local clock signal with a clock signal of the host device using a clock synchronization mechanism of the communications protocol. The USB device then determines a number of USB frames transmitted by the host device and processes the one or more USB frames based, at least in part, on the synchronized local clock signal. For some embodiments, the USB device may receive a frame count value and a corresponding media time value from the host device.

First claim

What is claimed is:

1. A method of operating a universal serial bus (USB) device on a network, the method comprising:
receiving one or more USB frames from a host device via the network, wherein the one or more USB frames are encapsulated in one or more data packets based on a communications protocol associated with network;
synchronizing a local clock signal of the USB device with a clock signal of the host device using a clock synchronization mechanism of the communications protocol;
receiving a frame count value from the host device, wherein the frame count value indicates a number of USB frames transmitted by the host device at a first instance of time;
receiving a media time value from the host device, wherein the media time value indicates the first instance of time at which the frame count value is recorded;
determining, at the USB device, a number of USB frames transmitted by the host device based, at least in part, on the synchronized local clock signal, the frame count value, and the media time value; and
processing the one or more USB frames based, at least in part, on the number of USB frames transmitted by the host device.

2. The method of claim 1 , wherein the communications protocol corresponds to an IEEE 802.11 wireless protocol.

3. The method of claim 1 , wherein synchronizing the local clock signal comprises:
receiving one or more beacon frames from the host device, wherein at least one of the beacon frames includes a timing synchronization function (TSF) value; and
adjusting the local clock signal based on the received TSF value.

4. The method of claim 1 , further comprising:
storing the one or more USB frames in a data buffer.

5. The method of claim 4 , wherein determining the number of USB frames transmitted by the host device comprises:
updating a local frame counter based, at least in part, on a number of the USB frames stored in the data buffer; and
determining the number of USB frames transmitted by the host device based on the local frame counter.

6. The method of claim 1 , wherein the frame count value and the media time value are received together in at least one of the USB frames.

7. The method of claim 5 , wherein determining the number of USB frames transmitted by the host device further comprises:
synchronizing the local frame counter with a USB frame counter in the host device based, at least in part, on the local clock signal, the frame count value, and the media time value.

8. The method of claim 7 , wherein processing the one or more USB frames comprises:
processing the one or more USB frames when the local frame counter reaches a first threshold.

9. A method of operating a computing device on a network, the method comprising:
encapsulating one or more universal serial bus (USB) frames in one or more data packets based on a communications protocol associated with the network;
transmitting the one or more data packets, including the one or more encapsulated USB frames, to one or more client devices via the network;
updating a USB frame counter based on a number of USB frames transmitted to the one or more client devices;
transmitting a frame count value to the one or more client devices, wherein the frame count value indicates a current value of the USB frame counter;
transmitting a media time value to the one or more client devices, wherein the media time value indicates a time at which the frame count value is recorded; and
transmitting a set of synchronization data, to the one or more client devices, that allows the one or more client devices to process the one or more USB frames, wherein the set of synchronization data includes clock synchronization data that allows the one or more client devices to determine a number of USB frames transmitted by the computing device based at least in part on the frame count value, the media time value, and respective local clock signals of the one or more client devices.

10. The method of claim 9 , wherein the communications protocol corresponds to an IEEE 802.11 wireless protocol.

11. The method of claim 10 , wherein transmitting the set of synchronization data comprises:
broadcasting the clock synchronization data within one or more beacon frames, wherein the clock synchronization data includes a timing synchronization function (TSF) value.

12. The method of claim 9 , further comprising:
encapsulating the frame count value and the media time value, together, in at least one of the one or more USB frames.

13. The method of claim 9 , further comprising:
transmitting a processing request to the one or more client devices, wherein the processing request includes an instruction to begin processing the one or more USB frames.

14. The method of claim 13 , wherein the processing request includes a frame count threshold, and wherein the one or more client devices are to begin processing the one or more USB frames when a number of USB frames transmitted by the computing device is equal to the frame count threshold.

15. The method of claim 14 , wherein the set of synchronization data allows the one or more client devices to begin processing the one or more USB frames, concurrently.

16. A universal serial bus (USB) device, comprising:
a receiver to receive one or more USB frames from a host device via a network, wherein the one or more USB frames are encapsulated in one or more data packets based on a communications protocol associated with the network;
one or more processors; and
a memory storing instructions that, when executed by the one or more processors, causes the USB device to:
synchronize a local clock signal of the USB device with a clock signal of the host device using a clock synchronization mechanism of the communications protocol;
receive a frame count value from the host device, wherein the frame count value indicates a number of USB frames transmitted by the host device at a first instance of time;
receive a media time value from the host device, wherein the media time value indicates the first instance of time at which the frame count value is recorded;
determine a number of USB frames transmitted by the host device based, at least in part, on the synchronized local clock signal, the frame count value, and the media time value; and
process the one or more USB frames based, at least in part, on the number of USB frames transmitted by the host device.

17. The USB device of claim 16 , wherein the wireless communications protocol corresponds to an IEEE 802.11 wireless protocol, and wherein the receiver is to further:
receive one or more beacon frames from the host device, wherein at least one of the beacon frames includes a timing synchronization function (TSF) value.

18. The USB device of claim 16 , wherein execution of the instructions to synchronize the local clock signal with the clock signal of the host device causes the USB device to:
adjust the local clock signal based on the received TSF value.

19. The USB device of claim 16 , further comprising:
a data buffer to store the one or more USB frames.

20. The USB device of claim 19 , wherein execution of the instructions to determine the number of USB frames transmitted by the host device causes the USB device to:
update a local frame counter based, at least in part, on a number of the USB frames stored in the data buffer; and
determine the number of USB frames transmitted by the host device based on the local frame counter.

21. The USB device of claim 16 , wherein the frame count value and the media time value

Assignees

• Qualcomm Inc

Inventors

• Tsfaty Yossef
• Wang Xiaodong
• Raissinia Alireza
• Raveendran Vijayalakshmi Rajasundaram
• Huang Xiaolong

Classifications

• G06F13/4282

  on a serial bus, e.g. I2C bus, SPI bus (on daisy chain buses G06F13/4247) · CPC title

• G06F2213/0042

  Universal serial bus [USB] · CPC title

• G06F13/4286 Primary

  using a handshaking protocol, e.g. RS232C link · CPC title

• H04J3/06

  Synchronising arrangements {(for television systems H04N5/04; bit-synchronisation H04L7/00)} · CPC title