Method for determining location of wireless devices

Patent metadata

Field	Value
Publication number	US-10039073-B2
Application number	US-201313964431-A
Country	US
Kind code	B2
Filing date	Aug 12, 2013
Priority date	Jan 3, 2013
Publication date	Jul 31, 2018
Grant date	Jul 31, 2018

Abstract

To determine a location of a client device in a wireless network having at least first and second network devices, with known locations, one of the network devices transmits a message to the other network device and the other network device responds with an acknowledgement message. A client device receives the message and the acknowledgement message as well as respective times indicating actual times at which the message and the acknowledgement message were processed by one of the first and second network devices. The client device determines its location based on the times at which it received the message and the acknowledgement message and the difference between the actual processing times. This location may be refined by determining an angle between the client device and at least one of the network devices having multiple antennas and being configured for steered beam communications.

First claim

What is claimed:

1. A method for determining a location of a client device in a wireless network, the method comprising:
receiving, at the client device from a first network device, a first message transmitted by the first network device to a second network device, wherein each of the first and second network devices has a known location;
determining, by the client device, a first time of arrival at the client device of the first message transmitted by the first network device to the second network device;
receiving, at the client device from the second network device, a second message transmitted from the second network device to the first network device, the second message comprising a time of reception of the first message by the second network device from the first network device and a time of transmission of an acknowledgement of the first message, transmitted by the second network device to the first network device;
determining, by the client device, a second time of arrival at the client device of the second message transmitted by the second network device to the first network device; and
calculating, by the client device, the location of the client device from the first time of arrival, the second time of arrival, the time of reception, the time of transmission, and the known locations of the first and second network devices.

2. The method according to claim 1 , wherein each of the first and second network devices comprises an antenna port and wherein the time of reception is a time at which the message is received at the antenna port of the second network device and the time of transmission is a time at which the acknowledgement of the message is transmitted from the antenna port of the second network device.

3. The method according to claim 1 , wherein the client device is a mobile wireless device and the first and second network devices are wireless access points on the wireless network.

4. The method of claim 1 , further comprising:
transmitting, by the client device, data representing respective times at which the message and the further message were received by the client device, the time of reception of the message by the second network device and the time of transmission of the acknowledgement by the second network device, to one of the first and second network devices; and
receiving from the one of the first and second network devices the calculated location of the client device.

5. The method of claim 1 , further comprising:
transmitting, by the client device, data representing respective times at which the message and the further message were received by the client device, the time of reception of the message by the second network device and the time of transmission of the acknowledgement by the second network device, to a location server that is separate from the client device and the first and second network devices; and
receiving from the location server the calculated location of the client device.

6. A method for determining a location of a client device in a wireless network, the method comprising:
transmitting, by a first network device, a first message to a second network device, wherein each of the first and second network devices has a known location;
receiving the first message by the second network device;
transmitting, by the second network device, an acknowledgement of the first message;
transmitting, by the first network device, a further message, the further message comprising a time of transmission of the first message and a time of reception of the acknowledgement from the second network device;
receiving, by the client device, the first message, the acknowledgement, and the further message comprising the time of transmission of the first message and the time of reception of the acknowledgement from the second network device;
determining, by the client device, a first time of arrival at the client device of the first message;
determining, by the client device, a second time of arrival at the client device of the acknowledgement; and
calculating the location of the client device from the first time of arrival, the second time of arrival, the time of transmission of the first message, the time of reception of the acknowledgement from the second network device, and the known locations of the first and second network devices.

7. The method according to claim 6 , wherein each of the first and second network devices comprises an antenna port and wherein the time of transmission is a time at which the first message is transmitted from the antenna port of the first other network device and the time of reception is a time at which the acknowledgement of the first message is received at the antenna port of the first network device.

8. The method according to claim 6 , wherein the client device is a mobile wireless device and the first and second network devices are wireless access points on the wireless network.

9. The method of claim 6 , further comprising:
transmitting, by the client device, data representing respective times at which the first message and the further message were received by the client device to one of the first and second network devices; and
receiving from the one of the first and second network devices the calculated location of the client device.

10. The method of claim 6 , further comprising:
transmitting, by the client device, data representing respective times at which the first message and the further message were received by the client device, the time of transmission of the first message by the first network device and the time of reception of the acknowledgement by the first network device, to a location server that is separate from the client device and the first and second network devices; and
receiving from the location server the calculated location of the client device.

11. A method for determining a location of a client device in a wireless network comprising the client device and a plurality of other network devices, each of the other network devices having a known location, the method comprising:
transmitting a request message from the client device to each of a plurality of other network devices and receiving an acknowledgement message from each of the plurality of other network devices, wherein each of the plurality of other network device has a known location;
estimating, after receiving the acknowledgement message from each of the plurality of other network devices, a round-trip time from the client device to each of the plurality of other network devices using respective times at which a signal transmitted to the other network device was transmitted from digital-to-analogue conversion (DAC) circuitry of the client device and was received by the other network device and respective times at which a corresponding signal received from the other network device was transmitted by the other network device and was received by analogue-to-digital conversion (ADC) circuitry of the client device, wherein the client device comprises an RF section and a digital section wherein receive circuitry of the RF section is coupled to the digital section by the ADC and the digital section is coupled to the transmit circuitry of the RF section by the DAC; and
calculating a location of the client device using the estimated round-trip times between the client device and each of the other network devices to cancel out processing delays through the RF section of the client device.

12. The method of claim 11 , further comprising:
receiving a first signal from each of the plurality of other network devices;
transmitting an acknowledgement signal to each of the plurality of other network devices; and
receiving,

Assignees

• Csr Tech Inc
• Qualcomm Inc

Inventors

• Kakani Naveen Kumar
• Tarlow Ben
• Lindskog Erik
• Banerjea Raja
• Wan Hong
• Blair Ian Charles

Classifications

• G01S5/08

  Position of single direction-finder fixed by determining direction of a plurality of spaced sources of known location · CPC title

• H04W64/00 Primary

  Locating users or terminals {or network equipment} for network management purposes, e.g. mobility management · CPC title

• G01S1/20 Primary

  using a comparison of transit time of synchronised signals transmitted from non-directional antennas or antenna systems spaced apart, i.e. path-difference systems · CPC title

• H04W4/023

  using mutual or relative location information between multiple location based services [LBS] targets or of distance thresholds · CPC title

• G01S11/02

  using radio waves (G01S19/00 takes precedence) · CPC title