Method and apparatus to determine time and distance between transceivers using phase measurements

An apparatus for estimating a round-trip time (RTT) in an orthogonal frequency division multiplexing (OFDM) system, the apparatus comprising:

• means for transmitting a first OFDM signal at a first transmit time (tT1) from a first transceiver to a second transceiver;
• means for receiving, at the first transceiver and from the second transceiver, a second OFDM signal in a window A having a window A start time (twindowA);
• and
• means for determining a window A phase difference (TΦA) from a first difference of a receive time (tR2) of the second OFDM signal and a window A start time (twindowA) of the window A.

An apparatus for estimating a round-trip time (RTT) in an orthogonal frequency division multiplexing (OFDM) system, the apparatus comprising:

• a first transceiver comprising:
• a transmitter configured to transmit a first OFDM signal at a first transmit time (tT1) from the first transceiver to a second transceiver;
• and
• a receiver configured to receive, at the first transceiver and from the second transceiver, a second OFDM signal in a window A having a window A start time (twindowA);
• and
• a processor coupled to the first transceiver and configured to determine a window A phase difference (TΦA) from a first difference of a receive time (tR2) of the second OFDM signal and the window A start time (twindowA).

A non-transitory computer-readable storage medium transceiver for estimating a round-trip time (RTT) in an orthogonal frequency division multiplexing (OFDM) system, the non-transitory computer-readable storage medium including program code stored thereon, comprising program code to:

• transmit a first OFDM signal at a first transmit time (tT1) from a first transceiver to a second transceiver;
• receive, at the first transceiver and from the second transceiver, a second OFDM signal in a window A having a window A start time (twindowA);
• and
• determine a window A phase difference (TΦA) from a first difference of a receive time (tR2) of the second OFDM signal and a window A start time (twindowA) of the window A.