FIELD OF THE DISCLOSURE

The present disclosure relates to automatic provisioning of wireless signal sources for subsequent use in geopositioning in areas with poor satellite coverage.

BACKGROUND

The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.

Navigation software available today cannot provide precise reliable navigation inside tunnels. More generally, geopositioning systems that rely on signals from satellites, such Global Positioning Service (GPS), do not work in areas where these signals are completely or substantially occluded by obstacles. Some devices in these situations rely on dead reckoning, or estimation of a change in position based on the speed at which the device is moving. However, dead reckoning accumulates errors, and accuracy quickly diminishes with changes in speed.

Meanwhile, navigation in tunnels remains a relevant problem as drivers often slow down and sometimes even come to a complete stop when checking for underground exits or turns. Especially as more and more drivers today become dependent on navigation systems telling them where and when they should turn, reliable geopositioning everywhere along a route, including inside tunnels, is important.

To use low-energy signal sources such as Bluetooth® or Wifi™ “beacons,” or Wifi™ access points, for geopositioning in areas with limited satellite coverage, the locations of the signal sources must be established prior to geopositioning receivers. Determining locations of signal sources can require land surveying, precise measurements, precise installation, etc. For example, to install signal sources at precisely known locations (or precisely determining the locations immediately upon installation) in general is difficult, time-consuming, and potentially disruptive of the operation of the tunnel.

SUMMARY

Using the techniques of this disclosure, a system automatically determines the locations of signal sources disposed in an area with limited satellite coverage, using signal data collected by receivers moving through the area. The signal data can include indications of how the strength of signals from several signal sources changes over time, and the system can identify observed or extrapolated peak values within the data to determine relative positioning of the signal sources. The system also can utilize known or conventionally determinable positions of signal sources located near the boundaries of the area with limited satellite coverage, e.g., the GPS coordinates of a signal source located just outside the entrance into a tunnel and the GPS coordinates of another signal source located outside the exit out of the tunnel. As discussed below, the techniques the system implements can include determining variations in speed of the receiver moving through the area, averaging of signal data from multiple receivers, profiling individual signal sources, etc.

According to another implementation, the system uses round trip-time (RTT) measurements which the signal sources collect when exchanging management frames. The system may use these measurements along with a description of the geometry of the path along which receivers move through the area with limited satellite coverage. In some cases, the system does not rely on the description of geometry and determines the locations of signal sources using multiple RTT measurements.

One particular embodiment of these techniques is a method for automatically determining geographic positions of signal sources in areas with limited satellite coverage. The method includes receiving, by one or more processors, signal data collected by a receiver moving along a path through a geographic area with limited satellite coverage, the signal data being indicative of changes, over a period of time, in strength of respective signals emitted by multiple signal sources statically disposed along the path. The method further includes receiving, by the one or more processors, indications of a first position of the receiver at a first time prior to entering the geographic area and a second position of the receiver at a second time subsequent to leaving the geographic area. Further, the method includes determining, by the one or more processors, positions for the signal sources using the received signal data and the received indications of the positions and the times and using the determined positions for the signal sources to geoposition a device moving along the path.

Another embodiment of these techniques is a system for geopositioning receivers in areas with areas with limited satellite coverage. The system includes one or more processors and a non-transitory computer-readable memory coupled to the one or more processor. The memory stores instructions that, when executed by the one or more processors, cause the system to implement the method outlined above.

Yet another embodiment is a method for automatically provisioning signal sources for operating in a geopositioning system. The method includes obtaining an indication of geometry along which signal sources are disposed, where the geometry describes a region of physical space. The method further includes receiving, from the signal sources, signal data indicative of distances between at least several of the signal sources, where the signal data is generated by the signal sources transmitting management frames. The method also includes determining, using the indication of the geometry and the received signal data, positions of the signal sources along the geometry, and using the determined positions of the signal sources to geoposition portable computing devices travelling through the region physical space.

