Apparatus and method for wi-fi station positioning

Abstract

A Wi-Fi access point AP (110) for determining the angle of arrival of RF transmissions from a Wi-Fi site (120). The Wi-Fi AP (110) is configured to: transmit a plurality of RF beacon beams (130a to 130d) along a plurality of directions pointing to a spatial region where the Wi-Fi site (120) is located; receive, for each of the plurality of RF beacon beams (130a to 130d), a signal strength measurement of the corresponding RF beacon beam (130a to 130d) received by the Wi-Fi site (120); and determine the angle of arrival of the Wi-Fi site (120) based on the plurality of signal strength measurements of the plurality of RF beacon beams (130a to 130d).

Description

Technical Field

[0001] This disclosure relates to wireless communications. More specifically, this disclosure relates to devices and methods for Wi-Fi site positioning. Background Technology

[0002] Traditional methods for locating Wi-Fi devices (e.g., Wi-Fi sites) from other Wi-Fi devices (e.g., Wi-Fi APs) can employ triangulation algorithms based on distance measurements called Received Signal Strength Indication (RSSI). However, traditional RSSI-based algorithms may offer low accuracy due to measurement inaccuracies in multipath scenarios (especially indoor environments), low RSS accuracy, and errors in RSSI-to-distance conversion, often requiring precise knowledge of the path loss (PL) model. Furthermore, the PL model can vary significantly (over time and on each device), particularly in larger communication units. Summary of the Invention

[0003] The aim is to provide improved devices, systems, and methods for Wi-Fi site location.

[0004] The foregoing and other objectives are achieved through the subject matter of the independent claims. Other implementations are apparent from the dependent claims, the specification, and the drawings.

[0005] According to a first aspect, a Wi-Fi access point (AP) is provided for determining the angle of arrival of an RF transmission signal from a Wi-Fi site. The Wi-Fi AP is configured to: transmit multiple RF beacon beams along multiple slightly different directions pointing towards a spatial area where the Wi-Fi site is located; receive, for each RF beacon beam, a signal strength measurement of the corresponding RF beacon beam measured by the Wi-Fi site; and determine the angle of arrival of the Wi-Fi site based on the multiple signal strength measurements of the multiple RF beacon beams.

[0006] In a further possible implementation, the Wi-Fi AP includes multiple antennas or smart antennas for transmitting multiple RF beacon beams in several slightly different directions.

[0007] In a further possible implementation, multiple signal strength measurements of multiple RF beacon beams include multiple Received Signal Strength Indications (RSSIs) of the multiple RF beacon beams.

[0008] In a further possible implementation, the Wi-Fi AP is configured to determine the angle of arrival of the Wi-Fi site based on multiple signal strength measurements of multiple RF beacon beams by: determining one or more differences between the signal strength measurements of the RF beacon beams in each of the multiple RF beacon beams for one or more pairs of RF beacon beams, and determining the angle of arrival of the Wi-Fi site based on the one or more differences.

[0009] In a further possible implementation, the Wi-Fi AP is configured to determine the angle of arrival of the Wi-Fi site using a maximum likelihood scheme based on multiple signal strength measurements of multiple RF beacon beams.

[0010] In a further possible implementation, the Wi-Fi AP is configured to determine the angle of arrival of the Wi-Fi site based on multiple signal strength measurements from multiple RF beacon beams using an optimization scheme based on the following equation.

[0011]

[0012] Where x represents a vector comprising multiple signal strength measurements of multiple RF beacon beams as components, a(θ) represents a vector comprising multiple antenna beam patterns associated with multiple RF beacon beams as components, and θ represents the search space or search grid on which optimization schemes are performed.

[0013] In a further possible implementation, the Wi-Fi AP is configured to determine the beam pattern associated with each of the multiple RF beacon beams based on an analytical approximation (particularly a Gaussian approximation) of the antenna beam pattern and / or a discrete representation of the beam pattern in a table stored in the Wi-Fi AP’s memory.

[0014] In a further possible implementation, the Wi-Fi AP is configured to use an alternative angle-of-arrival determination scheme, which determines a fine estimate of the angle of arrival of the Wi-Fi site based on the angle of arrival determined from multiple signal strength measurements of multiple RF beacon beams.

[0015] In a further possible implementation, the Wi-Fi AP is configured to receive multiple reporting messages from a Wi-Fi site, as defined in 802.11k. Each reporting message may include a signal strength measurement of the corresponding RF beacon beam received and measured by the Wi-Fi site.

[0016] In a further possible implementation, each of the multiple RF beacon beams has a different BSSID.

[0017] According to a second aspect, a Wi-Fi positioning system for determining the location of a Wi-Fi site is provided. The Wi-Fi positioning system includes a plurality of Wi-Fi access points (APs) according to the first aspect. Each Wi-Fi AP is configured to determine the angle of arrival of the Wi-Fi site. The Wi-Fi positioning system further includes a positioning unit configured to determine the location of the Wi-Fi site based on the multiple angles of arrival of the Wi-Fi site determined by the plurality of Wi-Fi APs, i.e., to locate the Wi-Fi site.

[0018] In a further possible implementation, one of the multiple Wi-Fi APs includes a positioning unit.

[0019] According to a third aspect, a method is provided for determining the angle of arrival of an RF transmission signal from a Wi-Fi site. The method includes:

[0020] Multiple RF beacon beams are transmitted from the Wi-Fi AP in several slightly different directions pointing towards the spatial area where the Wi-Fi site is located;

[0021] For each of the multiple RF beacon beams, receive signal strength measurements of the corresponding RF beacon beam received by the Wi-Fi station; and

[0022] The angle of arrival of a Wi-Fi site is determined based on multiple signal strength measurements from multiple RF beacon beams.

[0023] The method according to the third aspect of this disclosure can be performed by a Wi-Fi AP according to the first aspect of this disclosure. Therefore, further features of the method according to the third aspect of this disclosure arise directly from the functionality of the Wi-Fi AP according to the first aspect of this disclosure and its different implementations described above and below.

[0024] According to the fourth aspect, a computer program product is provided, the computer program product including a computer-readable storage medium for storing program code, which, when executed by a computer or processor, causes the computer or processor to perform the method of the third aspect.

[0025] Details of one or more embodiments are set forth in the accompanying drawings and the following description. Other features, objectives, and advantages will be apparent from the specification, drawings, and claims. Attached Figure Description

[0026] Embodiments of this disclosure are described in more detail below with reference to the accompanying drawings, in which:

[0027] Figure 1a and Figure 1bA Wi-Fi positioning system for determining the location of a Wi-Fi site according to an embodiment is shown;

[0028] Figure 2a and Figure 2b The antenna pattern of the AP according to an embodiment is shown;

[0029] Figure 3a and Figure 3b An amplitude pattern of the antenna of the AP according to an embodiment is shown;

[0030] Figure 4 This is a schematic diagram of the line-of-sight direction of the antenna and the RF transmission signal of the AP according to an embodiment;

[0031] Figure 5a and Figure 5b The antenna beam pattern noise of the AP according to an embodiment is shown;

[0032] Figure 6a and Figure 6b This is a schematic diagram of the multiple line-of-sight directions of multiple antennas and the RF transmission signal direction of an AP according to an embodiment;

[0033] Figure 7 An evaluation arrangement of the directional antenna for an AP according to an embodiment is shown;

[0034] Figure 8a and Figure 8b A perspective view and a top view of the smart antenna of the AP according to an embodiment are shown;

[0035] Figure 9a and Figure 9b The radiation pattern at the smart antenna of the AP according to an embodiment is shown;

[0036] Figure 10 The AOA performance of an AP with a smart antenna according to an embodiment is shown under different multipath parameters; and

[0037] Figure 11 This is a flowchart of a method for determining the angle of arrival of an RF transmission signal from a Wi-Fi site, according to an embodiment.

[0038] In the following text, the same reference numerals refer to the same or at least functionally equivalent features. Detailed Implementation

[0039] In the following description, reference is made to the accompanying drawings, which form a part of this disclosure, illustrating by way of description specific aspects of embodiments of this disclosure or aspects in which embodiments of this disclosure may be used. It should be understood that embodiments of this disclosure may be used in other aspects and include structural or logical variations not shown in the drawings. Therefore, the following detailed description should not be considered limiting, and the scope of this disclosure is defined by the appended claims.

[0040] For example, it should be understood that the disclosure relating to the described method can also be applied to corresponding devices or systems for performing the method, and vice versa. For example, if one or more specific method steps are described, the corresponding device may include one or more units, such as functional units (e.g., a unit that performs one or more steps; or multiple units, each performing one or more of the multiple steps), for performing the described one or more method steps, even if such one or more units are not explicitly described or shown in the drawings. On the other hand, for example, if a specific apparatus is described based on one or more units (e.g., functional units), the corresponding method may include a step for performing the function of one or more units (e.g., a step that performs the function of one or more units; or multiple steps, each performing the function of one or more of the multiple units), even if such one or more steps are not explicitly described or shown in the drawings. Furthermore, it should be understood that, unless otherwise specifically stated, features of the various exemplary embodiments and / or aspects described herein can be combined with each other.

[0041] Figure 1a and Figure 1b A Wi-Fi positioning system 100 for determining the location of a Wi-Fi site 120 is illustrated according to an embodiment. According to an embodiment, the Wi-Fi positioning system 100 includes a plurality of Wi-Fi APs 110, 110', 110'', etc. Figure 1a The Wi-Fi AP 110 is shown in the diagram. Each Wi-Fi AP 110, 110', 110" is configured to determine the angles of arrival 140, 140', 140" of Wi-Fi site 120. The Wi-Fi positioning system 100 includes a positioning unit configured to determine the location of Wi-Fi site 120 based on multiple angles of arrival 140, 140', 140" of Wi-Fi site 120 determined by the plurality of Wi-Fi APs 110, 110', 110" (i.e., to locate Wi-Fi site 120). One of the plurality of Wi-Fi APs 110, 110', 110" may include the positioning unit.

[0042] Wi-Fi APs 110, 110', 110" and Wi-Fi site 120 may be part of a wireless communication network. The wireless communication network may be a WLAN (also known as a Wi-Fi network) based on the IEEE 802.11 standard framework.

[0043] Each of the Wi-Fi APs 110, 110', and 110" may include processing circuitry 111 and a communication interface 113, particularly a wireless communication interface 113 according to the IEEE 802.11 standard framework. The corresponding processing circuitry 111 may be implemented in hardware and / or software and may include digital circuitry, or both analog and digital circuitry. The digital circuitry may include components such as application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), digital signal processors (DSPs), or general-purpose processors. Each of the Wi-Fi APs 110, 110', and 110" may also include a memory 115 configured to store executable program code that, when executed by the corresponding processing circuitry 111, causes the corresponding Wi-Fi AP 110, 110', and 110" to perform the functions and methods described herein.

[0044] As will be understood, although Figure 1b Three Wi-Fi APs 110, 110', 110" are shown, but the Wi-Fi positioning system 100 may include more or fewer than three Wi-Fi APs 110, 110', 110", and in particular one Wi-Fi AP 110.

[0045] As will be described in more detail below with respect to Wi-Fi AP 110, each of the Wi-Fi APs 110, 110', 110" is configured to: transmit a plurality of RF beacon beams 130a to 130d along a plurality of slightly different directions pointing toward the spatial area where Wi-Fi site 120 is located; receive, for each of the plurality of RF beacon beams 130a to 130d, signal strength measurements of the corresponding RF beacon beam 130a to 130d received by Wi-Fi site 120; and determine the angle of arrival 140 of Wi-Fi site 120 based on the plurality of signal strength measurements of the plurality of RF beacon beams 130a to 130d. One of the plurality of Wi-Fi APs 110, 110', 110" may include a positioning unit.

[0046] The Wi-Fi AP 110 may include multiple antennas or smart antennas for transmitting multiple RF beacon beams 130a to 130d in several slightly different directions. Multiple signal strength measurements of the multiple RF beacon beams 130a to 130d may include multiple received signal strength indicators (RSSIs) for the multiple RF beacon beams 130a to 130d.

[0047] Wi-Fi AP 110 can be configured to receive multiple reporting messages, as defined in 802.11k, from Wi-Fi site 120. Each reporting message may include a signal strength measurement of the corresponding RF beacon beam 130a to 130d received by Wi-Fi site 120. Each of the multiple RF beacon beams 130a to 130d may have a different BSSID.

[0048] According to an embodiment, the Wi-Fi AP 110 can use the following RSSI measurements: The Wi-Fi AP 110 can measure (i.e., calculate) the angle of arrival (AOA) 140° instead of measuring the distance (because the measured RSSI is actually an indication of the distance between two Wi-Fi entities). The Wi-Fi AP 110 can use the difference between two RSSIs (ΔRSSI), instead of the RSSI value itself, as a measurement of different antenna angles. The Wi-Fi AP 110 can utilize the known antenna pattern of a directional antenna or antenna array in the AOA calculation (using ΔRSSI).

[0049] The Wi-Fi AP 110 can measure the angle of arrival (AOA) using the directional pattern of an antenna array deployed on the AP side, instead of relying on distance measurements in traditional methods. Assuming a Gaussian-like radiation pattern for the directional antennas, impact signals will cause varying attenuation depending on the specific AOA 140. Since the transmit power of the client (i.e., Wi-Fi site 120) may be unknown, a single RSSI measurement obtained from a single directional antenna typically does not provide any angular information. This can be addressed by providing several (especially at least two) directional antennas and measuring the signal strength from the same source (i.e., Wi-Fi site 120) to extract AOA information (i.e., AOA 140).

[0050] For example, when two antennas are turned in different directions (with a known angle of view between their line of sight), the difference in signal power measured for impact signals at different antennas / beams can provide an angle of arrival (AOA) of 140° (up to the measurement noise). Known antenna patterns allow for AOA calculations using predefined tables or mathematical calculations. However, directly using directional antennas for communication while turning the line of sight of each antenna in different directions (regardless of the technique) can reduce SINR (@Rx), limit MIMO capabilities, and increase OBSS interference, i.e., degrade Wi-Fi network performance. Therefore, this technique may be detrimental for UL data.

[0051] To simplify AOA measurements without compromising communication operability, a "dual" approach can be used, employing DL data to obtain RSSI measurements. The Wi-Fi AP 110 can transmit beacons in different directions as part of the 802.11k protocol (these directions are defined in a directional grid (e.g., every 5-10 degrees) and at predefined angular regions), and the client (i.e., Wi-Fi station 120) can be the client measuring the RSSI of each received beacon. Different beams can be created using smart antennas (which can transmit signals in different directions), or, if a uniform omnidirectional antenna array is used, different beams can be created via digital beamforming, depending on the antenna configuration deployed on the AP side.

[0052] Then, the client (i.e., Wi-Fi site 120) can send the measured RSSI back to Wi-Fi AP 110, and Wi-Fi AP 110 can use the collected RSSI measurements to estimate AOA 140 with knowledge of the beam's directivity pattern.

[0053] Advantageously, the beacon can be transmitted at any cycle according to the desired angular resolution. For more accurate AOA140, denser angular searches can be performed. The achievable positioning accuracy of the embodiments disclosed herein can be significantly better than that of conventional RSSI-based methods, e.g., 2-3m versus 7-10m. Precise antenna pattern calibration may not be necessary, as the key characteristics of the directional antenna (e.g., pattern beamwidth, pattern distortion, sensitivity to polarization, etc.) can be known a priori from manufacturer information (datasheets) or preliminary measurements. Specific hardware requirements for the antenna array may not be required: directivity can be created using deployed antenna arrays, such as smart antennas or digital beamforming of linear arrays, depending on the current infrastructure.

[0054] Because WLAN protocols are developed to serve numerous users at any location within the coverage area of ​​an AP, meaning the Wi-Fi AP 110 may need to cover the entire area it operates in, its antenna may require an omnidirectional beam for wide coverage. Paradoxically, since omnidirectional antennas have low gain, for high gain, the antenna may need a directional (narrow) beam. Smart antennas are one solution to this conflicting requirement. They can provide both omnidirectional coverage and a directional beam pointing to a specific sector within the coverage area. The embodiments disclosed herein can utilize the directivity pattern of either a smart antenna or any directional antenna.

[0055] The main embodiments of the operation of the Wi-Fi AP 110 are described below in the context of multiple steps that the Wi-Fi AP 110 is configured to perform according to the embodiments.

[0056] exist Figure 1a In the first step shown, Wi-Fi AP 110 can send beacon sequences (with different BSSIDs) near the client's location (i.e., the location of Wi-Fi site 120).

[0057] In the second step, the client (i.e., Wi-Fi site 120) can measure the signal strength (RSSI) of each beacon and send it back to Wi-Fi AP 110, for example, using a beacon reporting mechanism as defined in 802.11k.

[0058] r1, r2...r N

[0059] In the third step, Wi-FiAP 110 can collect measured RSSI and apply a maximum likelihood algorithm (which requires prior knowledge of the antenna pattern) to estimate the angle of the client relative to the client (i.e., relative to Wi-Fi site 120). Figure 2a and Figure 2bAs shown, the antenna pattern of the Wi-Fi AP 110 is likely known, especially up to a certain level of uncertainty. Based on a smart antenna or directional antenna, the Wi-Fi AP 110 can approximate the pattern analytically using some approximation function (e.g., a Gaussian function with a known beamwidth as a parameter). Alternatively, the amplitude pattern, stored in a table as a function of AOA 140, can be used; this is typically available from the manufacturer or calibrated offline.

[0060] exist Figure 1b In the fourth step shown, since the estimated AOA 140 may have a coarse accuracy (e.g., 10-15 degrees), a client estimation using triangulation can be performed based on the corresponding RF transmission signals 150, 150', 150”, using the AOA 140 measured from several Wi-Fi APs 110, 110', 110” to a given client (i.e., Wi-Fi site 120).

[0061] In the fifth step, instead of the fourth step, the Wi-Fi AP 110 can be configured to assist in resolving ambiguities (if any) in the fine measurement of the AOA 140. Here, the angle 140 with respect to the client (i.e., Wi-Fi site 120) can be measured using the phase difference between the antennas. Since the distance between the antennas is greater than half a wavelength (which is typically the case for MIMO arrays designed to minimize radiative leakage between antennas), ambiguous AOA measurements may be obtained. In this case, the measurement performed by the embodiments disclosed herein provides a coarse AOA 140, which can be essentially defined and can be used to assist in resolving ambiguities in the fine measurement of the AOA 140.

[0062] The following will refer to further details. Figures 3a to 3b , Figure 4 , Figures 5a to 5b , Figures 6a to 6b as well as Figure 7 An embodiment of a Wi-Fi AP 110 with a directional antenna and the corresponding AOA estimation is described.

[0063] Typically, omnidirectional antennas are used in MIMO arrays where the antenna amplitude response is almost identical in all directions. In this case, different directions may not affect the measured signal strength. However, for directional antennas, maximum gain can be obtained in the line-of-sight direction 401 (…). Figure 4 As shown in the diagram, the gain may gradually decrease as the AOA 140 moves away from the line of sight direction 401. Therefore, the measured signal strength can carry angular information that can be extracted.

[0064] The main parameters inherent in the amplitude pattern that can be used for AOA calculations and also affect positioning performance can be one or more of the following: (i) the antenna beamwidth, which corresponds to an angle value where the amplitude gain is half of the maximum gain (which typically corresponds to the line-of-sight direction) and is measured at 401 in the line-of-sight direction of the antenna, i.e., 3 dB attenuation; (ii) the amplitude pattern approximation function, which can be approximated by a simple exponential function; and (iii) and / or pattern noise, which corresponds to the amplitude of the “ripples” covering the approximation function, which are typically caused by antenna polarization and other physical distortions.

[0065] An example of an amplitude pattern approximated by an exponential function (with a dual-sided 3-dB beamwidth of 46° (±23°) and no pattern noise) in Figure 3a The graph is shown in the middle, and in Figure 3b The corresponding curve is shown in polar coordinates.

[0066] like Figure 4 As shown, the Gaussian approximation of the antenna pattern can be given by the following formula:

[0067]

[0068] in, θ is the line-of-sight angle at 40°, and θ is the angle of arrival at 14°. B These parameters are derived from the 3-dB beamwidth parameter using simple mathematical derivation:

[0069]

[0070] Pattern noise can appear in the form of fluctuations, which is in Figure 5a and Figure 5b As shown in the image.

[0071] like Figure 6a As shown, since the transmitter power may be unknown, it may be necessary to combine several (i.e. at least two) antennas that are co-located and pointing in different line-of-sight directions 401, 401' in order to extract angle information based on the difference in measured signal strength.

[0072] In the given example, two similar antennas (with the same θ) can be used. 3dB Parameters (for simplicity, exemplified), view axis directions 401, 401' are represented as ), where each measurement is a different RSSI of the signal from direction θ, i.e., AOA 140. For a given Gaussian amplitude pattern, the measured RSSI can be given by the following formula:

[0073] as well as

[0074]

[0075] Where n1 and n2 are measurement noise.

[0076] When using the difference in measured amplitudes (in dB), AOA 140 can be analytically derived (for a given Gaussian radiation pattern):

[0077]

[0078] The solution can be given by the following formula:

[0079]

[0080] in,

[0081]

[0082] This method of estimating AOA 140 using analytical expressions is referred to below as the first estimate (or simply E1).

[0083] Figure 6b The following method is illustrated, employing more than two antennas, specifically n antennas oriented in different directions with corresponding line-of-sight directions 401, 401', 401" . Each antenna can measure the signal strength of the input signal, which can be organized in vector form. For the current multi-beam configuration, AOA 140 can be found by exhaustive search on the likelihood function and on a predefined angle grid.

[0084]

[0085] For a given example, the search grid can be defined in the region [0..90°] with a predefined step size Δθ. Here, a(θ) is the steering vector, which can be given by:

[0086]

[0087] Among them, 1 M It is a vector of dimension (M×1), and These are vectors corresponding to the line-of-sight directions of the antenna: 401, 401', 401".

[0088] If the AOA140 is quite far from one of the line-of-sight directions 401, 401', 401" of one of the beams / antennas, and the input signal is attenuated to the point that it drops below a certain predefined threshold, a given RSSI measurement can be discarded and not used by the estimation algorithm.

[0089] This method of estimating AOA 140 using analytical expressions is referred to below as the second estimate (or simply E2).

[0090] As described below, the performance of the algorithm can be evaluated for several scenarios, which differ from one another due to the amount of multipath signal reflection.

[0091] Figure 7 The arrangement of directional antennas for evaluation in the first scenario is shown. Here, a single main path is assumed, and two and three directional antennas are evaluated simultaneously, with an angle of 90 degrees or 45 degrees, depending on the configuration. The following simulation parameters are chosen for evaluation: SNR = 20 dB, pattern noise = ±1 dB, and antenna beamwidth: θ 3dB = ±15°, ±25°, ±35°, ±45°. Performance summary for the first scenario is as follows:

[0092] In Table 1, antenna is abbreviated as ant.

[0093]

[0094] Table 1: Evaluation results of directional antennas in the first scenario

[0095] In the second scenario, the algorithm's performance can be evaluated in a multipath scenario with several paths 2, 3, and 5, and also against a typical TGn (task group 11n channel) as "D"-LOS TGn. The performance summary for the second scenario is in Table 2, where antenna is abbreviated as ant.

[0096]

[0097] Table 2: Evaluation results of directional antennas in the second scenario

[0098] As shown in Table 2, for 5 antennas / beams and an antenna beamwidth of 30° (i.e. ±15°), an angle accuracy of 12° can be achieved.

[0099] While the performance presented above may be effective for several receiving directional antennas simultaneously measuring the RSSI of the input signals, the Wi-Fi AP 110 according to the embodiment can be configured to send beacons to a client (i.e., Wi-Fi site 120), particularly using a directional antenna, smart antenna, or beamforming, and the client (i.e., Wi-Fi site 120) can measure the RSSI of each beacon and send it back to the Wi-Fi AP 110. Here, the performance of the directional antenna as described above can remain effective.

[0100] The following is further reference Figure 8a To Figure 8c, Figures 9a to 9b as well as Figure 10 An embodiment of a Wi-Fi AP110 with a smart antenna and the corresponding AOA estimation is described.

[0101] Figure 8a and Figure 8b A smart antenna 800 of a Wi-Fi AP 110 according to an embodiment is shown. Figure 8b As shown, a smart antenna can redirect the beam in different directions. Figure 9a and Figure 9b The corresponding radiation pattern of the beam is shown. Based on the radiation pattern shown, the 3-dB beamwidth can be approximately ±25°, or 50° (both sides).

[0102] Using the smart antenna array 800 described above, if all polarized antennas of the smart antenna 800 are used, the beam can be turned once every 5°. If smart antennas 800 with the same polarization are used, eight antenna directions can be provided every 90° sector (i.e., approximately every 12°).

[0103] For a 5° grid, the AOA performance with different multi-paths is as follows: Figure 10 The curve is shown in the graph. Figure 10 In the diagram, curve 1001 represents one path (i.e., only a direct path, no multipath), curve 1003 represents two paths (a direct path plus one multipath), curve 1005 represents three paths, and curve 1007 represents five paths.

[0104] As shown in Table 3, when the environment includes 5 paths, the AOA error is likely to be 7° with a 90% probability. When using several APs (110", 110', 110") and triangulation, this AOA error can be further converted into a positioning error.

[0105]

[0106] Table 3: AOA Error Probability

[0107] Figure 11 This is a flowchart of a method 1100 for determining the angle of arrival 140 of an RF transmission signal 150 from a Wi-Fi site 120, according to an embodiment.

[0108] Method 1100 includes step 1101: transmitting multiple RF beacon beams 130a to 130d from Wi-Fi AP 110 in multiple slightly different directions pointing toward the spatial area where Wi-Fi site 120 is located.

[0109] Method 1100 further includes step 1103: for each of the plurality of RF beacon beams 130a to 130d, receiving from Wi-Fi site 120 the signal strength measurement value of the corresponding RF beacon beam 130a to 130d received by Wi-Fi site 120.

[0110] Method 1100 further includes step 1105: determining the angle of arrival 140 of Wi-Fi site 120 based on multiple signal strength measurements of multiple RF beacon beams 130a to 130d.

[0111] Since method 1100 can be implemented by Wi-Fi AP 110, further features of method 1100 come directly from the functionality of Wi-Fi AP 110 and its various embodiments described above and below.

[0112] Those skilled in the art will understand that the “blocks” (“units”) in the various figures (methods and apparatuses) represent or describe the functionality of embodiments of this disclosure (and are not necessarily individual “units” in hardware or software), and thus equivalently describe the functionality or features (unit = step) of apparatus embodiments and method embodiments.

[0113] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the embodiments of the described apparatus are merely exemplary. For example, the unit division is only a logical functional division, and in actual implementation, there may be other divisions. For example, multiple units or components may be combined or integrated into another system, or some features may be omitted or not performed. Furthermore, the mutual coupling or direct coupling or communication connection shown or discussed can be implemented by using some interface. Indirect coupling or communication connection between devices or units can be implemented in electronic, mechanical, or other forms.

[0114] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, may be located in one location, or may be distributed across multiple network units. Some or all of the units may be selected as needed to achieve the objective of the solution in the embodiment.

[0115] In addition, the functional units in the embodiments disclosed herein may be integrated into one processing unit, or each of the units may exist physically separately, or two or more units may be integrated into one unit.

Claims

1. A Wi-Fi access point AP (110) for determining the angle of arrival (140) of an RF transmission (150) from a Wi-Fi site (120), wherein, The Wi-Fi AP (110) is configured to: Multiple RF beacon beams (130a to 130d) are transmitted in multiple directions pointing towards the spatial area where the Wi-Fi site (120) is located; For each of the plurality of RF beacon beams (130a to 130d), receive from the Wi-Fi station (120) the signal strength measurement value of the corresponding RF beacon beam (130a to 130d) received by the Wi-Fi station (120); and The angle of arrival (140) of the Wi-Fi site (120) is determined based on the multiple signal strength measurements of the multiple RF beacon beams (130a to 130d).

2. The Wi-Fi AP (110) according to claim 1, wherein, The Wi-Fi AP (110) includes multiple antennas or smart antennas for transmitting the multiple RF beacon beams (130a to 130d) along the multiple directions.

3. The Wi-Fi AP (110) according to claim 1 or 2, wherein, The plurality of signal strength measurements of the plurality of RF beacon beams (130a to 130d) include the plurality of Received Signal Strength Indications (RSSI) of the plurality of RF beacon beams (130a to 130d).

4. The Wi-Fi AP (110) according to any one of the preceding claims, wherein, The Wi-Fi AP (110) is configured to determine the angle of arrival (140) of the Wi-Fi site (120) based on the plurality of signal strength measurements of the plurality of RF beacon beams (130a to 130d) by: determining one or more differences between the signal strength measurements of the RF beacon beams (130a to 130d) in each of the plurality of RF beacon beams (130a to 130d) for one or more pairs of RF beacon beams (130a to 130d), and determining the angle of arrival (140) of the Wi-Fi site (120) based on the one or more differences.

5. The Wi-Fi AP (110) according to any one of the preceding claims, wherein, The Wi-Fi AP (110) is configured to determine the angle of arrival (140) of the Wi-Fi site (120) based on the plurality of signal strength measurements of the plurality of RF beacon beams (130a to 130d) using a maximum likelihood scheme.

6. The Wi-Fi AP (110) according to claim 5, wherein, The Wi-Fi AP (110) is configured to determine the angle of arrival of the Wi-Fi station (120) based on the plurality of signal strength measurements of the plurality of RF beacon beams (130a to 130d) according to the following equation. (140): in: x represents a vector comprising the signal strength measurements of the plurality of RF beacon beams (130a to 130d) as components; and a(θ) represents a vector that includes multiple beam patterns as components associated with the multiple RF beacon beams (130a to 130d).

7. The Wi-Fi AP (110) according to claim 6, wherein, The Wi-Fi AP (110) is configured to determine the beam pattern associated with each of the plurality of RF beacon beams (130a to 130d) based on an analytical approximation of the beam pattern and / or a discrete representation of the beam pattern.

8. The Wi-Fi AP (110) according to any one of the preceding claims, wherein, The Wi-Fi AP (110) is configured to determine a fine estimate of the angle of arrival (140) of the Wi-Fi site (120) based on the angle of arrival (140) determined according to the plurality of signal strength measurements of the plurality of RF beacon beams (130a to 130d).

9. The Wi-Fi AP (110) according to any one of the preceding claims, wherein, The Wi-Fi AP (110) is configured to receive multiple reporting messages from the Wi-Fi site (120), wherein each reporting message includes the signal strength measurement of the corresponding RF beacon beam (130a to 130d) received by the Wi-Fi site (120).

10. The Wi-Fi AP (110) according to any one of the preceding claims, wherein, Each of the plurality of RF beacon beams (130a to 130d) has a different BSSID.

11. A Wi-Fi positioning system (100) for determining the location of a Wi-Fi site (120), wherein, The Wi-Fi positioning system (100) includes: A plurality of Wi-Fi APs (110, 110', 110") according to any one of the preceding claims, wherein each Wi-Fi AP (110, 110', 110") is configured to determine the angle of arrival (140, 140', 140") of the Wi-Fi site (120); and A positioning unit configured to determine the location of the Wi-Fi site (120) based on the plurality of angles of arrival (140, 140', 140") of the Wi-Fi site (120) determined by the plurality of Wi-Fi APs (110, 110', 110") 12. The Wi-Fi positioning system (100) according to claim 11, wherein, One of the plurality of Wi-Fi APs (110, 110', 110") includes the positioning unit.

13. A method (1100) for determining the angle of arrival (140) of an RF transmission (150) from a Wi-Fi site (120), wherein, The method (1100) includes: Multiple RF beacon beams (130a to 130d) are transmitted (1101) from the Wi-Fi AP (110) along multiple directions pointing to the spatial area where the Wi-Fi site (120) is located; For each of the plurality of RF beacon beams (130a to 130d), receive (1103) from the Wi-Fi station (120) the signal strength measurement value of the corresponding RF beacon beam (130a to 130d) received by the Wi-Fi station (120); and The angle of arrival (140) of the Wi-Fi site (120) is determined (1105) based on the multiple signal strength measurements of the multiple RF beacon beams (130a to 130d).

14. A computer program product comprising a computer-readable storage medium for storing program code, which, when executed by a computer or processor, causes the computer or processor to perform the method (1100) according to claim 13.

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