Direction finding positioning in wireless local area networks

Patent metadata

Field	Value
Publication number	US-10206122-B2
Application number	US-201515121044-A
Country	US
Kind code	B2
Filing date	Feb 24, 2015
Priority date	Feb 25, 2014
Publication date	Feb 12, 2019
Grant date	Feb 12, 2019

Abstract

A method of direction finding (DF) positioning in a wireless location area network (WLAN) is proposed. A multiple antenna IEEE 802.11 transmitting device can transmit signal preamble containing multiple Long Training Field (LTF) symbols in a radio frame from multiple antennas simultaneously, which allows a receiving device to resolve multiple DF sounding signals transmitted from the multiple antennas. As a result, angle of departure (AoD) of the transmitting device can be estimated by using the multiple resolved DF sounding signals from each antenna for DF positioning purpose.

First claim

What is claimed is:

1. A method comprising:
(a) receiving a radio frame transmitted from a wireless transmitting station via multiple antennas by a receiver in a wireless local area network (WLAN), wherein the radio frame comprise a preamble having a plurality of long training field (LTF) symbols;
(b) resolving a plurality of direction finding (DF) sounding signals corresponding to the multiple antennas, wherein each DF sounding signal contains a number of LTF symbols transmitted from each antenna of the transmitting station;
(c) estimating an angle of departure (AoD) based on the plurality of DF sounding signals; and
(d) determining receiving station location information based on the estimated AoD;
wherein non-pilot tones of each LTF symbol from each antenna is multiplied by an entry of a corresponding row vector of a matrix for transmission, wherein the matrix contains orthogonal row vectors.

2. The method of claim 1 , further comprising: obtaining location information, antenna platform orientation information, and antenna position and/or spatial signature information of the transmitting station and the multiple antennas.

3. The method of claim 1 , further comprising: receiving a null data packet announcement (NDPA) frame from the transmitting station indicating the immediate subsequent transmission of the DF sounding signals.

4. The method of claim 3 , wherein the NDPA frame comprises a specific group ID indicating the immediate subsequent transmission of the DF sounding signals.

5. The method of claim 3 , wherein the NDPA frame comprises predefined partial association IDs indicating the immediate subsequent transmission of the DF sounding signals.

6. The method of claim 1 , further comprising: receiving a fine-timing measurement (FTM) frame from the transmitting station, wherein an indication field of the FTM frame is set to a predefined value.

7. The method of claim 6 , wherein the DF sounding signals is a type of FTM frame.

8. The method of claim 1 , wherein the number of entries in each row vector is equal to the number of LFT symbols.

9. The method of claim 1 , wherein the DF sounding signal from each antenna is resolved by an inner product of a corresponding row vector of the orthogonal matrix and the received LTF symbols.

10. The method of claim 1 , wherein each LTF symbol contains groups of interleaving subcarrier tones, and wherein different groups of subcarrier tones are allocated to different antennas to form an interleaved LTF waveform for transmission.

11. The method of claim 10 , wherein each DF sounding signal is resolved by processing a corresponding group of subcarrier tones to extract the DF sounding signal transmitted from each antenna.

12. The method of claim 1 , wherein the receiver resolves the DF sounding signals from each antenna and uses a super-resolution or a Bartlett beamforming method to estimate the AoD.

13. The method of claim 1 , wherein the receiver resolves the DF sounding signals from each antenna and determining a spatial signature, and wherein the receiver estimates the AoD via finding a best match for the spatial signature from a set of known spatial signatures.

14. A wireless receiving station comprising: a receiver that receives a radio frame transmitted from a wireless transmitting station via multiple antennas in a wireless local area network (WLAN), wherein the radio frame comprises a preamble having a plurality of long training field (LTF) symbols; a signal processing circuit that resolves a plurality of direction finding (DF) sounding signals corresponding to the multiple antennas, wherein each DF sounding signal containing a number of LTF symbols transmitted from each antenna of the transmitting station; an angle of departure (AoD) circuit that estimates an angle of departure (AoD) based on the plurality of DF sounding signals; and a positioning circuit that determines receiving station location information based on the AoD;
wherein non-pilot tones of each LTF symbol is multiplied by an entry from an orthogonal row vector of a matrix for transmission, and each DF sounding signal is resolved at the receiver by an inner product of a corresponding row vector of the matrix and the received LTF symbol.

15. The station of claim 14 , wherein the receiving station obtains location information, antenna platform orientation information, and antenna positions of the transmitting station and the multiple antennas for determining the receiving station location information.

16. The station of claim 14 , wherein each LTF symbol contains groups of interleaved subcarrier tones, and wherein different groups of subcarrier tones are allocated to different antennas to form an interleaved LTF waveform for transmission, and wherein each DF sounding signal is resolved by processing a corresponding group of subcarrier tones to extract the DF sounding signal transmitted from each antenna.

17. A method comprising: (a) transmitting a direction finding (DF) sounding announcement frame by a wireless transmitting station in a wireless local area network (WLAN); and (b) transmitting a plurality of DF sounding signals from the wireless transmitting station via multiple antennas to a wireless receiving station, wherein each DF sounding signal comprises a preamble having a plurality of long training field (LTF) symbols, and wherein each DF sounding signal is transmitted from each antenna of the transmitting station;
wherein non-pilot tones of each LTF symbol is multiplied by an entry from an orthogonal row vector of a matrix for transmission.

18. The method of claim 17 , further comprising: transmitting location information, antenna platform orientation information, and antenna position and/or spatial signature information of the transmitting station and the multiple antennas.

19. The method of claim 17 , wherein the number of LFT symbols is equal to the number of entries in the row vector.

20. The method of claim 17 , wherein each LTF symbol contains groups of interleaved subcarrier tones, and wherein different groups of subcarrier tones are allocated to different antennas to form an interleaved LTF waveform for transmission.

21. The method of claim 17 , wherein the DF announcement frame comprises a specific group ID indicating the immediate subsequent DF sounding signals.

22. The method of claim 17 , wherein the DF announcement frame is a fine-timing measurement (FTM) frame, and wherein an indication field of the FTM frame is set to a predefined value.

Assignees

• Mediatek Inc
• Wang James June Ming
• Liu Jianhan
• Pare Jr Thomas Edward
• Wu Tianyu
• Bajko Gabor
• Hsu Yung Ping

Inventors

• Wang James June-Ming
• Liu Jianhan
• Pare Jr Thomas Edward
• Wu Tianyu
• Bajko Gabor
• Hsu Yung-Ping

Classifications

• G01S13/825

  with exchange of information between interrogator and responder · CPC title

• H04W4/021 Primary

  Services related to particular areas, e.g. point of interest [POI] services, venue services or geofences · CPC title

• G01S3/14

  Systems for determining direction or deviation from predetermined direction {(aerial arrangements for changing or varying the orientation or the shape of the directional pattern H01Q3/00; combinations of different interacting aerial units for giving a desired directional characteristic H01Q21/29; aerials or aerial systems providing at least two radiation patterns H01Q25/00)} · CPC title

• G01S5/06

  Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements (G01S5/12 takes precedence) · CPC title

• G01S5/12

  by co-ordinating position lines of different shape, e.g. hyperbolic, circular, elliptical or radial · CPC title