Scalable multi-channel ranging

摘要

Techniques are presented herein to coordinate ranging exchanges between base stations in order to enable any number of wireless devices in the vicinity of the base stations to obtain signals associated with ranging exchanges between base stations, time-of-departure report messages transmitted by the base stations to each other and time-of-arrival report messages transmitted by the base stations to each other, for use in computing the location of the wireless devices. Based on the multi-channel time-of-arrivals computed for the wireless device with respect to each base station, the multi-channel time-of-arrivals contained in the time-of-arrival report messages transmitted between base stations and the known locations of the base stations, a physical location is computed for the wireless device.

主权项

1. A method comprising:
at a first base station among a plurality of base stations operating in a wireless network in which a wireless client device is configured to access the wireless network via one of the plurality of base stations, on each of multiple channels, performing ranging exchanges with each of a plurality of other base stations among the plurality of base stations and storing baseband samples of received ranging signals associated with the ranging exchanges for each of the multiple channels; sending from the first base station time-of-departure report messages including information indicating: single-channel time-of-departures for ranging signals transmitted by the first base station on respective ones of the multiple channels, the channel on which the ranging signals were each sent and the destination base station to which each ranging signal was sent; receiving time-of-departure report messages from each of the plurality of other base stations, each time-of-departure report message including information indicating, for the base station that is the source of the time-of-departure report message: a plurality of single-channel time-of-departures for respective ranging signals transmitted by the base station that is the source of the time-of-departure report message on respective ones of the multiple channels on which the ranging signals were each sent and the destination base station to which each ranging signal was sent, computing multi-channel wireless channel responses between the first base station and each of the plurality of other base stations based on the stored samples of received ranging signals on each of the multiple channels and the time-of-departure report messages received from the each of the plurality of other base stations, wherein the computing each multi-channel wireless channel response corresponding to each of the plurality of other base stations includes: mixing the baseband samples of the received ranging signals from a corresponding one of the plurality of other base stations with offset frequencies for corresponding ones of the multiple channels to produce mixed samples for the corresponding ones of the multiple channels; and summing the mixed samples for the corresponding ones of the multiple channels to produce a composite multi-channel measured signal as the multi-channel wireless channel response; computing multi-channel time-of-arrivals between the base station and each of the plurality of other base stations based on the multi-channel wireless channel responses; wherein the computing the multi-channel time-of-arrivals includes computing each of the multi-channel time-of-arrivals corresponding to each of the other base stations by: computing a composite multi-channel reference time from the mixed samples associated with the corresponding ones of the multiple channels; and cross-correlating the multi-channel wireless channel response with the composite multi-channel reference time to produce the multi-channel time-of-arrival; and sending time-of-arrival report messages to each of the plurality of other base stations, each time-of-arrival report message including information representing a plurality of multi-channel time-of-arrivals from respective received ranging signals during ranging exchanges on the multiple channels.