Abstract: A method in a mobile station (STA) configured to associate to an access point (AP) is described. The method includes determining an identifiable random medium access control (MAC) address (IRMA), associating to the AP and transmitting the IRMA to the AP during the association. The method also includes using the IRMA as the transmitter address (TA) a next time the STA begins to associate to the AP, where the IRMA is usable by the AP to identify the STA prior to a next association, determining a new IRMA, and transmitting the new IRMA to the AP during the next association. One or more additional associations to the AP are performed at least by transmitting at least a corresponding IRMA to the AP and indicating that the corresponding IRMA is a TA of the STA.

Abstract: Methods and apparatus are disclosed for determining a confidence ellipse (CEP) that encompasses possible locations of one or more target devices, which is a condition that may exist when a wireless device (WD) is initially travelling on an effectively straight path. The method includes calculating the deviation from the straight line path for the WD. If it is determined that the path is effectively a straight line, the calculation of the sum of squared residuals (SSRs) is extended so as to encompass two possible minima. A grid is then derived comprising all ground plane points, where the SSR values are (i) less than a boundary value and (ii) include the SSRs corresponding to the two possible minima. The grid is converted into a polygon, which is further converted into an ellipse displayed as the CEP. The CEP encompasses two possible locations of a target device.

Abstract: A method for operating a mobile station (STA) to periodically change its medium access control (MAC) address includes transmitting, from a STA, a first capability indication to an access point (AP) indicating that the STA supports identifiable random MAC (IRM). The STA receives a second capability indication from the AP indicating that the AP supports IRM. A first IRM address (IRMA) is determined and a first association between the STA and the AP is established using the first IRMA. A determination is made whether to change a MAC address of the STA. In response to a determination to change the MAC address of the STA, without disconnecting from the AP, a second IRMA is determined and a second association between the STA and the AP is established using the first IRMA. During the second association, the second IRMA is transmitted from the STA to the AP.

Abstract: A method for determining an angle of arrival (AoA) of a radio frequency (RF) signal received at an antenna array. The method includes determining theoretical signals to be received at an antenna array having first and second antenna pairs. Antennas of the first antenna pair are offset from each other by a first offset angle and antennas of the second antenna pair are offset from each other by a second offset angle. A look-up table is generated based on the theoretical signals. An RF signal is received at each antenna pair and the antenna outputs in each antenna pair are combined to produce first and second difference values. The first and second difference values are compared to theoretical difference values in the look-up table. A measured AoA of the RF signal is determined based on the comparison of the first and second difference values to the theoretical difference values.

Abstract: A method for determining a geo-location of a target station. The method includes transmitting a plurality of ranging packets to a target station and receiving a plurality of response packets transmitted by the target station in response. A plurality of round-trip times (RTTs) are determined based on the ranging packets and the response packets. A plurality of angles of arrival (AOAs) are determined based on the response packets. First and second pluralities of squared residuals are calculated for the plurality of RTTs and the plurality of AOAs, respectively. A third plurality of squared residuals is generated by summing the first and second pluralities. A minimum of a sum of the third plurality is calculated to identify best-fit location parameters for the target station. A circular error probability (CEP) ellipse is generated using the best-fit location parameters and a geo-location of the target station is determined based on the CEP ellipse.

Abstract: A method for operating a mobile station (STA) to periodically change its medium access control (MAC) address includes transmitting, from a STA, a first capability indication to an access point (AP) indicating that the STA supports identifiable random MAC (IRM). The STA receives a second capability indication from the AP indicating that the AP supports IRM. A first IRM address (IRMA) is determined and a first association between the STA and the AP is established using the first IRMA. A determination is made whether to change a MAC address of the STA. In response to a determination to change the MAC address of the STA, without disconnecting from the AP, a second IRMA is determined and a second association between the STA and the AP is established using the first IRMA. During the second association, the second IRMA is transmitted from the STA to the AP.

Abstract: A method in a mobile station (STA) configured to associate to an access point (AP) is described. The method includes determining an identifiable random medium access control (MAC) address (IRMA), associating to the AP and transmitting the IRMA to the AP during the association. The method also includes using the IRMA as the transmitter address (TA) a next time the STA begins to associate to the AP, where the IRMA is usable by the AP to identify the STA prior to a next association, determining a new IRMA, and transmitting the new IRMA to the AP during the next association. One or more additional associations to the AP are performed at least by transmitting at least a corresponding IRMA to the AP and indicating that the corresponding IRMA is a TA of the STA.

Abstract: A method and devices are disclosed for geo-location of wireless local area network (WLAN) devices. According to one aspect, a method for determining a corrected round trip times (RTT) resulting from communication with a WD is provided. The WD is configured with one or two short interframe spacings (SIFS). The method includes performing RTT measurements at successive times. The method includes determining a presence of one or two modes based at least in part on peaks of a kernel density estimation (KDE) surface. The KDE surface is determined from the RTT measurements. When there is only one mode, a corrected RTT is determined based on the RTT measurements and a first SIFS. When there are two modes, a corrected RTT is determined based on the RTT measurements and the first SIFS plus an SIFS offset (?), ? being based at least in part on a difference between the two modes.

Abstract: A method for detecting a preamble waveform of a received signal is described. The method includes dividing a correlation into a plurality of sub-correlations, for a plurality of frequency offset indices, k, covering a range of frequency offsets. The correlation has a correlation length equal to N, and a plurality of sub-correlations has a sub-correlations quantity equal to I, each sub-correlation of the plurality of sub-correlations has a sub-correlation length equal to M. A complex oscillation for a template frequency offset associated with k is approximated, the approximation is to be constant over an M-sample interval and is a piece-wise approximation. The approximated complex oscillation has length I. A quantity I of sub-correlations at each k is assembled using the approximated complex oscillation of length I. The method further includes determining that the received signal comprises the preamble based on the assembled sub-correlations and a correlation threshold.

Abstract: A method for determining a geo-location of a target station. The method includes transmitting a plurality of ranging packets to a target station and receiving a plurality of response packets transmitted by the target station in response. A plurality of round-trip times (RTTs) are determined based on the ranging packets and the response packets. A plurality of angles of arrival (AOAs) are determined based on the response packets. First and second pluralities of squared residuals are calculated for the plurality of RTTs and the plurality of AOAs, respectively. A third plurality of squared residuals is generated by summing the first and second pluralities. A minimum of a sum of the third plurality is calculated to identify best-fit location parameters for the target station. A circular error probability (CEP) ellipse is generated using the best-fit location parameters and a geo-location of the target station is determined based on the CEP ellipse.

Abstract: A method of determining a location of a wireless device. The method includes receiving a plurality of beacons, via a measuring station, transmitted from the wireless device. For each beacon, a Times of Arrival (TOA), a Times of Departure (TOD), and a location of the measuring station is identified. A plurality of split time candidates are calculated based on an orbit period of the measuring station and a plurality of cluster modes are calculated for the identified TOAs. A plurality of optimal split times are selected based on the plurality of split time candidates, the plurality of cluster modes, and a beacon drift. A plurality of circular error probability (CEP) ellipses are generated corresponding to the plurality of optimal split times. The plurality of CEP ellipses are merged and a location of the wireless device is determined based, at least in part, on the merged CEP ellipse.

Abstract: A method for determining a geo-location of a target station includes transmitting a plurality of ranging packets to a target station and receiving a plurality of response packets transmitted by the target station. A plurality of round-trip times (RTTs) are determined based on the ranging packets and the response packets. A plurality of angles of arrival (AOAs) are determined based on the response packets. First location vectors are determined based on the pluralities of RTTs and AOAs. Second location vectors are determined based on location parameters of the measuring station and the target station. Squared residual vectors are generated based on the first and second pluralities. A minimum of a sum of the squared residual vectors is calculated to identify best-fit location parameters for the target station. A circular error probability (CEP) ellipse is generated using the best-fit location parameters and a geo-location of the target station is determined.

Abstract: A method and Bluetooth mobile device are disclosed for geo-locating a plurality of target Bluetooth devices. In some embodiments, a method includes distinguishing between time delays associated with received response packets from different target Bluetooth devices based at least in part on Access Codes derived from unique lower address part (LAP) of the received response packets; and determining a location for each of the target Bluetooth devices based at least in part on the time delay associated with the response packet received from the target Bluetooth device.

Abstract: A method and apparatus for measuring the angle of arrival AOA of Wi-Fi packets, using a switched beam antenna SBA is described. Wide antenna beams, quadrants, are selected in turn and a burst of packets is transmitted on each quadrant. The quadrant with the highest average signals strength is selected. Then the narrow antenna beams that make up that selected quadrant are selected, in sequence, and the average signal strength for each narrow beam is recorded. The narrow beam with the highest average signal strength is returned as the AOA. Based upon which narrow beam recorded the highest signal strength, the next sequence of antenna beams is selected. When the SBA is mounted on a mobile platform, the parameters of the transmission bursts are chosen such that the angular error due to cornering of the platform is negligible.

Abstract: A method and devices are disclosed for geo-location of wireless local area network (WLAN) devices. According to one aspect, a method for determining a corrected round trip times (RTT) resulting from communication with a WD is provided. The WD is configured with one or two short interframe spacings (SIFS). The method includes performing RTT measurements at successive times. The method includes determining a presence of one or two modes based at least in part on peaks of a kernel density estimation (KDE) surface. The KDE surface is determined from the RTT measurements. When there is only one mode, a corrected RTT is determined based on the RTT measurements and a first SIFS. When there are two modes, a corrected RTT is determined based on the RTT measurements and the first SIFS plus an SIFS offset (?), ? being based at least in part on a difference between the two modes.

Abstract: A method in a first wireless device (WD) is described. The method includes determining one round trip time (RTT) of a first set of RTTs. The method also includes, at set intervals (TK), determining a set of mode peaks of the first set of RTTs, determining that the first SIFS mode has the highest mode peak of the set of mode peaks, determining that the second SIFS mode has the second highest peak of the set of mode peaks, determining a mode difference (TD), and adjusting the second subset of RTTs at least by adding or subtracting TD to each RTT of the second subset of RTTs. The method also includes determining a second set of RTTs comprising the first subset of RTTs and the adjusted second subset of RTTs, the second set of RTTs corresponding to the adjusted single SIFS mode.

Abstract: A method and apparatus for measuring confidence in the angle of arrival AOA of Wi-Fi packets, from a target station, using a switched beam antenna SBA is described. AOAs can be inaccurate due to reflections and multipaths. To assess the confidence of an AOA, each AOA is first converted to relative north, AOAt, and checked that at least M AOAs have been received in time T. If so, the standard deviation is calculated for of all the AOAs received during previous time T. If the standard deviation is less than a preset value, and the receiving station is not stationary, then the AOAt is considered to have high confidence and may be used to calculate the target station location. A vector display of the AOA uses the standard deviation to display the AOA vector as a varying length or a varying beamwidth corresponding to the standard deviation.

Abstract: A method and apparatus for measuring the angle of arrival AOA of Classic Bluetooth Basic Rate (BR) packets, using a switched beam antenna SBA is described. Paging packets are transmitted and wide antenna beams, quadrants, are selected in turn until the paging response is received. After transmitting the synchronization packet and the temporary connection is established, narrow antenna beams are selected, in sequences and the average signal strength for each beam is recorded, for each sequence. The beam with the highest signal strength is returned as the AOA. Based upon which beam recorded the highest signal strength, the next sequence of antenna beams is selected.

Abstract: A method for detection of an orthogonal frequency division multiplex (OFDM) packet preamble is described. The method includes quantizing a real part and an imaginary part of each complex template value to a template index value, determining a plurality of non-zero template index values based on the quantization, receiving a signal including a plurality of samples, performing a plurality of first sums, where each first sum sums a sample subset of plurality of sample subsets, and assigning the plurality of non-zero template index values to the plurality of first sums. The method further includes performing a transposition of each first sum using the assigned non-zero template index value, performing a second sum, where the second sum is a complex weighted sum of the transposition of each first sum, and determining that the received signal comprises the OFDM packet preamble based on the complex weighed sum.

Abstract: A method and apparatus for measuring the angle of arrival AOA of Wi-Fi packets, using a switched beam antenna SBA is described. Wide antenna beams, quadrants, are selected in turn and a burst of packets is transmitted on each quadrant. The quadrant with the highest average signals strength is selected. Then the narrow antenna beams that make up that selected quadrant are selected, in sequence, and the average signal strength for each narrow beam is recorded. The narrow beam with the highest average signal strength is returned as the AOA. Based upon which narrow beam recorded the highest signal strength, the next sequence of antenna beams is selected. When the SBA is mounted on a mobile platform, the parameters of the transmission bursts are chosen such that the angular error due to cornering of the platform is negligible.