Method to Synchronize Receiver's Clock to Transmitter's Clock at Sub-100Nsec
A sender ( 702 ) transmits one or more frames to a receiver ( 704 ). The receiver ( 704 ) either calculates a carrier frequency difference or a time difference using the one or more frames. A clock ( 722 ) in the receiver ( 704 ) is synchronized with a clock ( 714 ) in the sender ( 702 ) using the carrier frequency difference or the time difference.
1 . A method for synchronizing a clock in a receiving device to a clock in a sending device in a wireless network, comprising: receiving a first frame; determining a first time representing when the first frame is received by the receiving device; receiving a second frame; determining a second time representing when the second frame is received by the receiving device; calculating a time difference using the first and second times; and synchronizing the clock in the receiving device to the clock in the sending device using the time difference.
2 . The method of claim 1 , wherein receiving a first frame comprises receiving a first MMC frame.
3 . The method of claim 2 , wherein receiving a second frame comprises receiving a second MMC frame.
4 . The method of claim 2 , wherein receiving a second frame comprises receiving a USB data frame.
5 . The method of claim 1 , wherein determining a first time indicating when the second frame is received by the receiving device comprises appending a first timestamp to the first frame.
6 . The method of claim 5 , wherein determining a second time indicating when the second frame is received by the receiving device comprises appending a second timestamp to the second frame.
7 . The method of claim 6 , wherein calculating a time difference using the first and second times comprises calculating a time difference using the first and second timestamps.
8 . A method for synchronizing a clock in a receiving device to a clock in a sending device in a wireless network, comprising: receiving a frame comprised of a preamble and a header; calculating a carrier frequency difference using the preamble and the header; and synchronizing the clock in the receiving device to the clock in the sending device using the carrier frequency difference.
9 . The method of claim 8 , wherein calculating a carrier frequency difference using the preamble and the header comprises calculating a carrier frequency difference using a PLCP preamble and a PLCP header.
10 . The method of claim 8 , wherein calculating a carrier frequency difference using the preamble and the header comprises obtaining a carrier frequency difference from one or more bits in a pad field in the frame.
11 . A receiving device, comprising: a clock; and a controller operable to calculate a time difference between a first time representing when a first frame is received and a second time representing when a second frame is received and operable to adjust the clock using the calculated time difference.
12 . The receiving device of claim 11 , wherein the first frame comprises a first MMC frame.
13 . The receiving device of claim 12 , wherein the second frame comprises a second MMC frame.
14 . The receiving device of claim 12 , wherein the second frame comprises a USB data frame.
15 . The receiving device of claim 11 , wherein the controller is operable to append a first timestamp to the first frame and a second timestamp to the second frame, and wherein the controller is operable to calculate a time difference using the first and second timestamps.
16 . A receiving device comprising: a clock; and a controller operable to determine a carrier frequency difference using a received frame and operable to adjust the clock using the calculated carrier frequency difference.
17 . The receiving device of claim 16 , wherein the received frame comprises a preamble and a header and wherein the controller is operable to determine the carrier frequency difference using the preamble and the header.
18 . The receiving device of claim 17 , wherein the frame comprises a MAC PHY frame and the preamble and header comprise a PLCP preamble and a PLCP header.
19 . The receiving device of claim 16 , wherein the frame comprises a MBOA MAC PHY frame and wherein the controller is operable to determine the carrier frequency difference from one or more data bits in a pad field in the MBOA MAC PHY frame.