Method and system for accurate clock synchronization through interaction between communication layers and sub-layers for communication systems
First Claim
1. A method of time synchronization in a wireless communication system, comprising:
- transmitting a synchronization frame from a wireless transmitter to a wireless receiver over a wireless communication medium, wherein the synchronization frame includes a timestamp comprising a transmitting time indicating the wireless transmitter local time when a symbol at a predefined position of the synchronization frame is placed on the wireless communication medium for transmission, said predefined position is set to a particular point of one of a preamble and a header of the synchronization frame based on the wireless transmitter determining actual local time when said symbol at said predefined position is transmitted on the wireless communication medium using a particular time information parameter that carries a time value for said predefined position, and the parameter is transmitted at a physical medium dependent (PMD) sub-layer of a physical (PHY) layer of the wireless transmitter;
receiving the synchronization frame at a PHY layer of the wireless receiver;
determining a receiving time comprising the wireless receiver local time when said symbol of the synchronization frame was received from the wireless communication medium at the PHY layer of the wireless receiver;
time synchronizing the wireless receiver with the wireless transmitter by;
determining a difference between said timestamp and said receiving time; and
adjusting the wireless receiver local time based on said difference to time synchronize the wireless receiver with the wireless transmitter,wherein a media access control (MAC) layer of the wireless transmitter determines the actual local time based on communication from a PHY layer convergence procedure (PLCP) sub-layer of the wireless transmitter PHY layer.
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Abstract
Time synchronization in a wireless communication system comprises transmitting a synchronization frame from a transmitter to a receiver over a wireless communication medium. The synchronization frame includes a timestamp indicating the transmitter local time when a symbol at a predefined position of the synchronization frame is placed on the wireless communication medium for transmission. The synchronization frame is received at the receiver which determines a receiving time comprising the receiver local time when said symbol of the synchronization frame was received at the physical layer of the receiver. Time synchronizing is performed by determining a difference between said timestamp and said receiving time, and adjusting the receiver local time based on said difference to time synchronize the receiver with the transmitter.
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Citations
55 Claims
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1. A method of time synchronization in a wireless communication system, comprising:
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transmitting a synchronization frame from a wireless transmitter to a wireless receiver over a wireless communication medium, wherein the synchronization frame includes a timestamp comprising a transmitting time indicating the wireless transmitter local time when a symbol at a predefined position of the synchronization frame is placed on the wireless communication medium for transmission, said predefined position is set to a particular point of one of a preamble and a header of the synchronization frame based on the wireless transmitter determining actual local time when said symbol at said predefined position is transmitted on the wireless communication medium using a particular time information parameter that carries a time value for said predefined position, and the parameter is transmitted at a physical medium dependent (PMD) sub-layer of a physical (PHY) layer of the wireless transmitter; receiving the synchronization frame at a PHY layer of the wireless receiver; determining a receiving time comprising the wireless receiver local time when said symbol of the synchronization frame was received from the wireless communication medium at the PHY layer of the wireless receiver; time synchronizing the wireless receiver with the wireless transmitter by; determining a difference between said timestamp and said receiving time; and adjusting the wireless receiver local time based on said difference to time synchronize the wireless receiver with the wireless transmitter, wherein a media access control (MAC) layer of the wireless transmitter determines the actual local time based on communication from a PHY layer convergence procedure (PLCP) sub-layer of the wireless transmitter PHY layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A wireless communication system, comprising:
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a wireless transmitter; and a wireless receiver; the wireless transmitter comprising a synchronization interface configured to transmit a synchronization frame to the wireless receiver over a wireless communication medium, the synchronization frame including a timestamp comprising a transmitting time indicating the wireless transmitter local time when a symbol at a predefined position of the synchronization frame is placed on the wireless communication medium for transmission, wherein said predefined position is set to a particular point of one of a preamble and a header of the synchronization frame based on the wireless transmitter determining actual local time when said symbol at said predefined position is transmitted on the wireless communication medium using a particular time information parameter that carries a time value for said predefined position, and the parameter is transmitted at a physical medium dependent (PMD) sub-layer of a physical (PHY) layer of the wireless transmitter; the wireless receiver comprising a synchronization interface configured to determine a receiving time comprising the wireless receiver local time when said symbol of the synchronization frame was received from the wireless communication medium at a PHY layer of the wireless receiver, and to provide the received synchronization frame to a higher communication layer at the wireless receiver, wherein the synchronization frame arrives at said higher communication layer at an arriving time indicating a wireless receiver local time at which the synchronization frame arrived at said higher communication layer; the wireless receiver synchronization interface is configured to time synchronize the wireless receiver with the wireless transmitter by being configured to; determine a difference between said timestamp and said receiving time; and adjust the wireless receiver local time with said difference to time synchronize the wireless receiver with the wireless transmitter, wherein a media access control (MAC) layer of the wireless transmitter determines the actual local time based on communication from a PHY layer convergence procedure (PLCP) sub-layer of the wireless transmitter PHY layer. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41)
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42. A wireless receiver, comprising:
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a wireless receiver physical (PHY) layer configured to perform wireless communication to receive a synchronization frame over a wireless communication medium, the synchronization frame including a timestamp comprising a transmitting time indicating a wireless transmitter local time when a symbol at a predefined position of the synchronization frame is placed on the wireless communication medium for transmission to the wireless receiver, wherein said predefined position is set to a particular point of one of a preamble and a header of the synchronization frame based on the wireless transmitter determining actual local time when said symbol at said predefined position is received, from a physical medium dependent (PMD) sub-layer of a wireless transmitter physical (PHY) layer, on the wireless communication medium using a particular time information parameter that carries a time value for said predefined position; and a synchronization interface configured to determine a receiving time comprising the wireless receiver local time when said symbol of the synchronization frame was received from the wireless communication medium at the PHY layer of the wireless receiver, and to provide the received synchronization frame to a higher communication layer at the wireless receiver, wherein the synchronization frame arrives at said higher communication layer at an arriving time indicating a wireless receiver local time at which the synchronization frame arrived at said higher layer; the wireless receiver synchronization interface is configured to time synchronize the wireless receiver with the wireless transmitter by being configured to; determine a difference between said timestamp and said receiving time; and adjust the wireless receiver local time with said difference to time synchronize the wireless receiver with the wireless transmitter, wherein a media access control (MAC) layer of the wireless transmitter obtains the actual local time based on communication from a PHY layer convergence procedure (PLCP) sub-layer of the wireless transmitter PHY layer. - View Dependent Claims (43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55)
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Specification