| 摘要 |
A ranging operation between a first wireless device D1 and a second wireless D2 is performed by: sending (504), to the second wireless device, a data frame including a request for the second wireless device to report its actual SIFS duration to the first wireless device; determining (505) a time of departure (TOD) of the data frame; receiving (516), from the second wireless device, a response frame including SIFS information indicative of the actual SIFS duration of the second wireless device; determining (518) a time of arrival (TOA) of the response frame; and determining (522) a round trip time (RTT) of the data frame and the response frame using the TOD of the data frame, the TOA of the response frame, and the actual SIFS duration of the second wireless device. 501). Device D2 determines (508) the TOA of the received frame by capturing a time stamp, creates a response frame and determines (510) the TOD of the response frame, determines (512) ist actual SIFS duration, and embeds (514) the SIFS information into the response frame. The response frame is preferably an acknowledgement frame (ACK). Wireless devices D1 and D2 preferably include an SIFS database that stores a number of previously determined SIFS durations for the wireless device, one or more median SIFS durations for wireless device, and/or whether other wireless devices support ranging operations in accordance with the example embodiments. The exchange of ranging capabilities informs each of wireless devices D1 and D2 whether the other one supports capturing timestamps and/or is able to determine its own SIFS duration. In this manner, the ranging operations may be performed without estimating the SIFS duration of the second wireless device, thereby eliminating ranging errors resulting from uncertainties in the SIFS duration of the second wireless device. |
