Method and apparatus for determining distance in a Wi-Fi network
AssigneeQUALCOMM Incorporated
InventorsQifan Chen, Kai Shi, Ning Zhang
Life of this patent
Estimating the term…
Abstract
A method and apparatus for improving the accuracy of a round trip time (RTT) estimate between a first device and a second device are disclosed. The method involves calculating an acknowledgement correction factor and a unicast correction factor. These correction factors are used to compensate for symbol boundary time errors resulting from multipath effects.
Claims19
A method for improving accuracy of a round trip time (RTT) estimate between a first device and a second device, the method comprising:
- transmitting a unicast packet from the first device to the second device;
- determining a unicast correction factor (CORR_UNC) using a processor in the second device, wherein the unicast correction factor is to compensate for multipath effects upon the unicast packet;
- embedding the unicast correction factor in an acknowledgment packet in the second device;
- transmitting the acknowledgment packet from the second device to the first device;
- determining an acknowledgment correction factor (CORR_ACK) using a processor in the first device, wherein the acknowledgment correction factor is to compensate for multipath effects upon the acknowledgment packet;
- and
- calculating the RTT estimate in the first device using the unicast correction factor and the acknowledgment correction factor.
A system for improving accuracy of a round trip time (RTT) estimate between a first device and a second device, comprising:
- means for transmitting a unicast packet from the first device to the second device;
- means for determining a unicast correction factor (CORR_UNC) using a processor in the second device, wherein the unicast correction factor is to compensate for multipath effects upon the unicast packet;
- means for embedding the unicast correction factor in an acknowledgment packet in the second device;
- means for transmitting the acknowledgment packet from the second device to the first device;
- means for determining an acknowledgment correction factor (CORR_ACK) using a processor in the first device, wherein the acknowledgment correction factor is to compensate for multipath effects upon the acknowledgment packet;
- and
- means for calculating the RTT estimate in the first device using the unicast correction factor and the acknowledgment correction factor.
A method for improving accuracy of a round trip time (RTT) estimate between a first device and a second device, the method comprising:
- receiving a unicast packet from the first device;
- receiving an acknowledgment packet from the second device by the first device;
- determining an acknowledgment correction factor (CORR_ACK) using a processor in the first device, wherein the acknowledgment correction factor is to compensate for multipath effects upon the acknowledgment packet, and wherein determining the acknowledgment correction factor further comprises:
- determining a cyclic shift diversity (CSD) value for the second device;
- and
- subtracting a selected multiple of the determined CSD value from the acknowledgment correction factor;
- and
- calculating the RTT estimate in the first device using the acknowledgment correction factor.
Dependencies are inferred from the claim text.