WO2023165698A1

WO2023165698A1 - Device for positioning in an indoor environment and method for determining a position of a device in an indoor environment

Info

Publication number: WO2023165698A1
Application number: PCT/EP2022/055424
Authority: WO
Inventors: Zhibin Yu; Xiaofeng Wu; Bin Yang; Pascal SCHLACHTER; Naveed IQBAL; Simon TEJERO ALFAGEME; Stefan Feuchtinger; Alberto PEREZ MONJAS
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2022-03-03
Filing date: 2022-03-03
Publication date: 2023-09-07
Also published as: CN118511090A

Abstract

The present disclosure relates to a device for positioning in an indoor environment, the environment comprising passive reflectors of at least two reflector types. The device is configured to transmit a radio signal in the environment; receive a reflected waveform of the transmitted radio signal; determine, using the received reflected waveform, a position feature set; and determine a position of the device in the environment by comparing the determined position feature set with a database comprising a plurality of position feature sets. Each of the plurality of position feature sets is associated with a different position in the environment. The determined position feature set comprises relative position information of the position of the device with regard to K passive reflectors, K being an integer number greater than or equal to three, and reflector type information of each of the K passive reflectors.

Description

DEVICE FOR POSITIONING IN AN INDOOR ENVIRONMENT AND METHOD FOR DETERMINING A POSITION OF A DEVICE IN AN INDOOR ENVIRONMENT

TECHNICAL FIELD

The disclosure relates to a device for positioning in an indoor environment and a method for determining a position of a device in an indoor environment. Further, the disclosure relates to a system of three or more passive reflectors of at least two reflector types and a method for arranging three or more passive reflectors of at least two reflectors types. Furthermore, the disclosure relates to a database for positioning in an indoor environment, and a method for generating such a database.

BACKGROUND

The disclosure is in the field of positioning in an indoor environment. In this regard, positioning in an indoor environment comprises or means determining a position in the indoor environment. For example, the disclosure is directed to determining a position of a device in an indoor environment.

SUMMARY

The following considerations are made by the inventors:

High-accuracy indoor positioning is in high demand in the industry domain e.g. smart factories. With regard to such indoor positioning, optimizing the trade-off among positioning accuracy, cost (terminal cost, anchor cost, spectrum resource cost, deployment effort) and system robustness is a field of research. The terminal cost may comprise or be the cost to produce or purchase the hardware of a terminal device of the positioning system. Anchor cost may comprise or be the cost to produce or purchase the hardware of anchor devices (reference point devices) of the positioning system. In a positioning system for positioning in an indoor environment, reference points (may be called anchors) may be arranged in the indoor environment for allowing the positioning. That is, the reference points may be used for determining or computing a position (e.g. coordinates of the position) in the indoor environment. The term “location” may be used as a synonym for the term “position”.

Indoor positioning may be based on wireless (radio) based methods. For example, indoor positioning using ultra-wideband (UWB) based solutions and cellular based solutions may achieve a good positioning accuracy (i.e. a position in the indoor environment may be determined with a good or high accuracy) with low terminal costs (i.e. costs required for the terminal of the positioning system). However, the anchor (reference points) cost is high because the UWB based solutions and cellular based solutions all require multiple active reference points e.g. in the form base stations to be deployed within the indoor environment. This causes high effort for installation and higher energy consumption.

Further, radio fingerprint based indoor positioning methods may be used for positioning in an indoor environment. The basic principle is that, when a terminal transmits a signal to one or more base stations (i.e. active reference points), the observed channel state information (CSI) at the base station side is strongly correlated to the terminal’s position within the environment, and therefore may be used as a radio fingerprint of the terminal’s position. By pre-generating a database of those radio fingerprints, the terminal’s position may be run-time reversely derived based on the run-time channel estimates at the base station side . Such radio fingerprint based indoor positioning methods may achieve good positioning accuracy. However, it has the following drawbacks. A terminal antenna may be located far away from a base station antenna. As a result, non-line-of-sight (NLOS) channel conditions may occur which degrade the positioning accuracy. To compensate for such conditions, multiple active indoor base stations need to be installed, which introduce again anchor cost issues and installation effort, as mentioned above with regard to the UWB based solutions and cellular based solutions. Further, a radio fingerprint is a set of signal strengths and phases (e.g. for OFDM system, it may be a set of strengths/phases for many subcarriers over the full bandwidth), which is associated to a position (e.g. position coordinates) in the indoor environment. The radio fingerprint varies with respect to different radio parameters (e.g. carrier frequencies). As a result, it requires a huge effort to generate the radio fingerprint database by pre-scanning the CSI for all indoor positions and for all operation bands in the real indoor environment. Furthermore, radio fingerprints may be sensitive to environment changes (dynamics) or radio frequency (RF) impairments. For example, the movement of a desk or a cabinet in a room (being the indoor environment) may drastically change the CSI fingerprints. This can cause mismatch problems and can significantly degrade the positioning accuracy of the radio fingerprint based indoor positioning method. Further, RF impairments such as frequency offset errors or I/Q imbalance may cause imperfect channel estimation at the base station side. This also significantly degrades the positioning accuracy of the radio fingerprint based indoor positioning method.

In view of the above, the present disclosure aims to provide a device for an improved positioning in an indoor environment. In particular, an objective is to improve positioning in an indoor environment. Further, an objective may be to provide an improved method for determining a position of a device in an indoor environment.

The objective is achieved by the subject-matter of the enclosed independent claims. Advantageous implementations are further defined in the dependent claims. A first aspect of the disclosure provides a device for positioning in an indoor environment. The environment comprises passive reflectors of at least two reflector types. The device is configured to transmit a radio signal in the environment, and receive a reflected waveform of the transmitted radio signal. Further, the device is configured to determine, using the received reflected waveform, a position feature set. Furthermore, the device is configured to determine a position of the device in the environment by comparing the determined position feature set with a database comprising a plurality of position feature sets. Each of the plurality of position feature sets is associated with a different position in the environment. The determined position feature set comprises relative position information of the position of the device with regard to K passive reflectors and reflector type information of each of the K passive reflectors. K is an integer number greater than or equal to three.

In other words, the first aspect of the disclosure proposes using passive reflectors of at least two reflector types of an indoor environment and a device configured to transmit a radio signal for positioning in the indoor environment. The device may determine its position in the indoor environment by transmitting the radio signal. The passive reflectors of the environment may reflect the radio signal transmitted by the device and the device may receive a reflected waveform of the transmitted radio signal. The device may determine a position feature set based on the received reflected waveform. Thus, the device of the first aspect does not require multiple active reference points, such as indoor base stations or indoor access points (APs), as positioning reference points. Instead, passive reflectors may be used as positioning reference points, which are lower in costs compared to active reference points.

The device may be configured to apply active radio sensing for positioning in the indoor environment (determining its position in the environment). Namely, the device may be configured to transmit a radio signal in the indoor environment and compute a position feature set based on a reflected waveform of the transmitted radio signal (i.e. its own transmitted radio signal). This allows detecting the nearby or nearest passive reflectors of the passive reflectors of the indoor environment as reference points for determining the position of the device in the environment (i.e. for positioning in the environment). In other words, to apply active radio sensing of the nearby or nearest passive reflectors of the indoor environment, the device may be configured to transmit a radio signal and then receive a reflected waveform of the transmitted radio signal. The device is configured to determine, using the received reflected waveform, the position feature set and to determine the position of the device in the environment by comparing the determined position feature set with a database comprising a plurality of position feature sets. The position of the device that may be determined by the device may be the absolute position of the device in the indoor environment. For example, the device may determine the position of the device in the form of coordinates indicating a position (absolute position) in the indoor environment. With other words, the device may be configured to determine information (position information) on its position or location in the indoor environment. For example, the position information may be in the form of coordinates of a position or location of the indoor environment. The position information may be referred to as absolute position information.

Compared to existing indoor positioning methods, the steps performed by the proposed device allow a positioning method that is inexpensive and has low-energy consumption. Namely, the anchor (reference points) that are arranged in the environment for a positioning by the device of the first aspect are passive reflectors that are low in costs and are energy free (i.e. they do not need to be electrically supplied). Moreover, the device according to the first aspect is robust against disaster scenarios. For example in a fire disaster situation, active reference points (e.g. base stations) may stop functioning due to failure of the energy supply of the active reference points. Thus, the above-mentioned positioning methods, such as radio fingerprint based indoor positioning methods, UWB based solutions and cellular based solutions, cannot work probably or stop working in the disaster situation, e.g. fire disaster situation. As a result, performing positioning is not possible in the disaster situation. Further, in such a fire situation, positioning method based on Lidar (light detection and ranging) and/or cameras may also not function probably or stop functioning due to strong smokes. Besides this, Lidar based solutions for positioning suffer under high terminal costs and camera based solutions for positioning have a low accuracy. Since the device according to the first aspect does not require active reference points, the device may perform positioning in the disaster situation, even in case the disaster situation (e.g. fire disaster situation) disturbs or stops an electrical energy supply in the indoor environment. For this, the device may comprise an own electrical energy source, such as a battery. The battery is optionally rechargeable. Therefore, the device may be advantageous for rescuing in a disaster situation, because the device may continue to perform positioning in the indoor environment in the disaster situation.

Furthermore, although the device is configured to determine a position feature set and compare the position feature set with a database for determining the position of the device; the position feature set, in contrast to a radio fingerprint used in radio fingerprint based indoor positioning, does not rely on the characteristics of the radio signals. The position feature set depends on the geometrical layout of the passive reflectors in the indoor environments. This provides the benefits that the device according to the first aspect and the positioning performable by the device is not sensitive to environment changes (dynamics) nor to RF impairments, as it is the case for the radio fingerprint based indoor positioning (assuming the arrangement of the passive reflectors is not changed). This makes the device of the first aspect and the positioning performable by the device robust with low calibration effort. Moreover, the device according to the first aspect does not need a frequent interaction between the device and one or more base stations (active reference points). The device may be configured to determine its own position in a full autonomous manner. This reduces the control overhead and control latency for indoor positioning. Furthermore, the device according to the first aspect does not need to know the absolute position of the passive reflectors of the indoor environment for determining the position of the device in the environment. The determined position feature set comprises relative position information of the position of the device with regard to K passive reflectors. Thus, the device of the first aspect and the method performable by the device of the first aspect for positioning is advantageous with regard to a positioning method using trilateration. Namely, when performing trilateration for determining a position, the absolute position of each of the detected reference points used for determining the position needs to be known.

By comparing the determined position feature set (determined for a current position of the device) with the database (pre-generated database) of the plurality of position feature sets the current position of the device may be determined.

The phrase “comparing the determined position feature set with a database” may be understood as “comparing the determined position feature set with entries of the database”. That is, since the database comprises a plurality of position feature sets, the device may be configured to compare the determined position feature set with the plurality of position feature sets of the database.

The indoor environment may be or may be part of an area of a building, e.g. a room of a workspace, a hall of a factory etc.

The passive reflectors may be referred to as passive local reference points (passive LRPs) or artificial passive reference reflectors. The passive reflectors are configured to reflect radio signals (e.g. the radio signal transmittable by the device) with one or more pre-characterized (may be abbreviated by “characterized”) reflection coefficients. The term “passive LRP fingerprint” may be used as synonym for the position feature set. The database may be referred to as “position feature set database” or “LRP fingerprint database”. From the point of view of the device the passive reflectors may be local, i.e. the device may detect or interact only with nearby passive reflectors (near the position of the device), because only nearby passive reflectors contribute to the reflected waveform by reflecting the transmitted radio signal. From the point of view of the device the passive reflectors may be referred to as non-unique (e.g. same type of passive reflectors in different places or positions of the indoor environment may be detected by the device at the same time).

The device may be configured to determine its position in the environment by transmitting at its position the radio signal. The device may be configured to receive at its position the reflected waveform of the transmitted signal. The device may be configured to determine the absolute position of the device as the position of the device in the environment. For example, the device may be configured to determine the coordinates of the device (i.e. of the position of the device) in the indoor environment.

The determined position feature set may comprise the relative position information of the position of the device with regard to K passive reflectors of the passive reflectors of the environment. This may be the case, when K passive reflectors or more reflectors of the environment contributed to the reflected waveform of the transmitted radio signal.

In case the reflected waveform of the transmitted radio signal is formed by reflections of the transmitted radio signal from less than K passive reflectors of the passive reflectors of the environment, the relative position information with regard to the missing passive reflectors of the K passive reflectors and the reflector type information of each of the missing passive reflectors of the K passive reflectors may be zero padded, i.e. comprise or be zero or any other default value. Thus, in this case the determined position feature set may still comprise K entries of relative position information and reflector type information. For example, in case K is equal to three (K = 3) and only two passive reflectors of the environment have contributed to the received reflected waveform, then the determined position feature set may still comprise three entries (K entries) of relative position information and reflector type information. However, in this case, only two entries of the position feature set correspond to actual passive reflectors of the environment, namely the two passive reflectors that contributed to the received reflected waveform, whereas one entry of the position feature set is zero padded or comprises a default value. That is, one entry of the position feature set does not correspond to an actual passive reflector of the passive reflectors of the environment. In this case, the aforementioned two entries of the position feature set comprises or correspond to relative position information of the position of the device with regard to the two passive reflectors of the passive reflectors of the environment, and reflector type information of each of the two passive reflectors. In the aforementioned example, the position feature set may be said to comprise relative position information of the position of the device with regard to three passive reflectors, and reflector type information of each of the three passive reflectors. Two of the three passive reflectors are actual passive reflectors of the environment and one passive reflector of the three passive reflectors is an artificial or dummy passive reflector representing the one missing passive reflector. The relative position information and reflector type information of the artificial or dummy passive reflector equals to zeros (due to zero padding) or another default value.

The device may be a terminal device. The radio signal may be a cellular communication signal (e.g. an uplink sounding signal or an uplink data signal) which is transmitted by the terminal device to a base station. Optionally, when the terminal is configured to transmit the cellular communication signal using orthogonal frequency-division multiplexing (OFDM) modulation, the device (e.g. a receiver of the device) may be configured to perform self-interference cancellation (SIC) with regard to a reflected waveform of the cellular communication signal in order to suppress self-interference.

The reflector type information of a passive reflector may comprise or be the reflector type of the passive reflector. That is, the reflector type information of a passive reflector may indicate the reflector type of the passive reflector.

The passive reflectors of the at least two reflector types may comprise one or more metal reflectors (e.g. spherical metal reflector(s) and/or trihedral comer reflectors) and/or one or more dielectric reflectors (e.g. Luneburg lens(es)). The one or more dielectric reflectors may be referred to as dielectric based reflectors. The aforementioned passive reflectors may generate strong reflected power, so that reflected radio signals (reflected from respective passive reflectors) are stronger (i.e. have greater power) compared to scattering interferences from the environment. The passive reflectors may have one or more pre-characterized reflection coefficients, which allow distinguishing radio signals reflected from the passive reflectors to be distinguished from other scatters within the environment. For example, the one or more pre-characterized reflection coefficients may comprise or be a radar-cross-section (RCS). In addition or alternatively, the one or more pre-characterized reflection coefficients may comprise or be polarimetry features. In this case, the device may comprise one or more linear dual-polarized antennas configured to transmit the radio signal and receive the reflected waveform of the transmitted radio signal.

The polarimetry features may be defined by a 2x2 scattering matrix as shown in the following equation:

wherein S is the scattering matrix and o is the RCS characterized by the reflector type (e.g. a spherical metal reflector has a different RCS compared to a trihedral comer reflector). The term "(phh " is the absolute phase depending on the distance between the position of the device from which a radio signal is transmitted to a respective passive reflector that reflects the transmitted radio signal. The terms “ /iv ^— (phh " and “<p_vv — (phh " are relative phase characteristics per reflector type.

Compared to RCS, polarimetry features may comprise additional relative phase information among polarized antenna pairs that may optionally be comprised by the device for transmitting a radio signal. The RCS and/or the polarimetry features may be used for characterizing a passive reflector and, thus, determining reflector type information (i.e. the reflector type) of the passive reflector. As outlined above, the device may be configured to classify or distinguish a passive reflector (e.g. a radio signal reflected by the passive reflector) from background scattering within the indoor environment by determining or measuring the RCS and/or the polarimetry features of the passive reflector (e.g. the radio signal reflected from the passive reflector). This allows the device to classify or distinguish different types of passive reflectors.

The device may be configured to move in the indoor environment and determine its position in the environment while moving by iteratively or repetitively transmitting a radio signal, receiving the reflected waveform of the respective transmitted radio signal, determining a respective position feature set and determining the respective position of the device using the determined respective position feature set. In other words, the device may move to a new position and determine the new position of the device by transmitting at the new position a radio signal, receiving a reflected waveform caused by the radio signal transmitted at the new position, determining a position feature set for the new position using the received reflected waveform and determining the new position of the device (i.e. the position of the device at the new position) using the position feature set determined for the new position. The device may be configured to determine its position and use the determined position for navigating in the indoor environment.

When the device is moving, the device may be configured to combine position feature sets, which have been determined from historical measurements to improve the detection accuracy of its position (i.e. accuracy of determining its position) and, thus, accuracy of positioning. The device may be configured to explore or use mobility information, e.g. velocity information of the device, to improve the positioning accuracy, for example to predict future position feature sets for future positions of the device. When the device is moving within the indoor environment, the device may repetitively determine the position of the device (by performing the above described steps performable by the device) so as to achieve a consecutive position determination of the device.

The device may comprise one or more antennas, a transceiver (e.g. radio frequency (RF) transceiver) and a processor (e.g. baseband processor). The transceiver may operate in the radio frequency range. The transceiver and the one or more antennas may be configured to transmit the radio signal in the indoor environment and receive the reflected waveform of the transmitted radio signal. The processor may be configured to determine, using the received reflected waveform, the position feature set. Further, the processor may be configured to determine the position of the device (e.g. absolute position of the device) in the indoor environment by comparing the determined position feature set with the database. The processor may be configured to use the determine position of the device for navigation of the device in the indoor environment.

The device may comprise an own electrical energy source (local energy source), such as one or more batteries. The one or more batteries may be re-chargeable. This allows the device to perform positioning in the indoor environment independent of a situation of the indoor environment (e.g. independent of whether a disaster situation such as a fire is present or not). A disaster situation of the environment does not have an impact on the passive reflectors, as outlined above.

In an implementation form of the first aspect, the relative position information of the determined position feature set comprises distance information and/or angle information of the position of the device with regard to the K passive reflectors of the determined position feature set.

The distance information of the position of the device with regard to a passive reflector may be or may indicate a distance from the position of the device to the passive reflector. The term “range” may be used as a synonym for the term “distance”. The angle information of the position of the device with regard to a passive reflector may be or may indicate one or more relative angles from the position of the device to the passive reflector. The distance information and/or angle information of the position of the device with regard to the K passive reflectors allow describing a position of the device with regard to K nearby or nearest passive reflectors (i.e. passive reference points) of the indoor environment. Thus, the distance information and/or angle information may be used for describing a relative position of the device in the indoor environment. This position information relies on the geometrical layout of the passive reflectors in the indoor environment and does not rely on characteristics of radio signals transmittable by the device. This provides the benefits that the device according to the first aspect is not sensitive to environment changes nor RF impairments.

In an implementation form of the first aspect, the device comprises two or more antennas configured to transmit the radio signal and receive the reflected waveform of the transmitted radio signal. The relative position information of the determined position feature set may comprise the angle information of the position of the device with regard to the K passive reflectors of the determined position feature set.

The two or more antennas may be directional antennas. The two or more antennas may be separate antennas or part of an antenna array.

In an implementation form of the first aspect, each position feature set of the database comprises the relative position information of the position, associated with the respective position feature set, with regard to K passive reflectors of the passive reflectors of the environment, and the reflector type information of each of the K passive reflectors.

In an implementation form of the first aspect, the relative position information of each position feature set of the database comprises distance information and/or angle information of the position, associated with the respective position feature set, with regard to the K passive reflectors of the respective position feature set.

The distance information of the position, associated with the respective position feature set, with regard to a passive reflector may be or may indicate a distance from the position, associated with the respective position feature set, to the passive reflector. The angle information of the position, associated with the respective position feature set, with regard to a passive reflector may be or may indicate one or more relative angles from the position, associated with the respective position feature set, to the passive reflector.

In an implementation form of the first aspect, the device is configured to measure propagation parameters of the received reflected waveform and translate the propagation parameters into relative position information of the position of the device with regard to passive reflectors that contributed to the received reflected waveform.

The propagation parameters may comprises propagation gain and/or propagation phases of the received reflected waveform.

In an implementation form of the first aspect, the device is configured to determine the reflector type information of each of passive reflectors that contributed to the received reflected waveform using one or more pre-characterized reflection coefficients of the at least two reflector types. The one or more precharacterized reflection coefficients may comprise a radar-cross-section (RCS) and/or polarimetry features.

In an implementation form of the first aspect, the device is configured to compute, for passive reflectors that contributed to the received reflected waveform, the relative position information of the position of the device with regard to the passive reflectors, and the reflector type information of each of the passive reflectors. The device may be configured to select, according to the computed relative position information, among the passive reflectors that contributed to the received reflected waveform the K passive reflectors of the determined position feature set.

That is, the device may be configured to determine, for passive reflectors that contributed to the received reflected waveform, the relative position information of the position of the device with regard to the passive reflectors. The device may be configured to select, according to the determined relative position information, among the passive reflectors that contributed to the received reflected waveform the K passive reflectors of the determined position feature set. The device may be configured to determine, for the passive reflectors that contributed to the received reflected waveform, the reflector type information of each of the passive reflectors.

In other words, the device is configured to select among the passive reflectors that contributed to the received reflected waveform the most suitable passive reflectors as the K passive reflectors of the determined position feature set. That is, in case the device detects more than K passive reflectors, the device may be configured to down-select the detected passive reflectors to K passive reflectors. Being suitable may be determined based on the relative position information. In other words, a selection criteria may be based on sorted relative position information (e.g. distance) of the position of the device with regard to the passive reflectors contributing to the received reflected waveform. That is, among the passive reflectors that contribute to the received reflected waveform the K nearest passive reflectors (being nearest with regard to the device’s position) may be selected for the position feature set. Alternatively or additional the selection criteria may be based on sorted signal to noise ratio (SNR) measurements for the passive reflectors that contributed to the received reflected waveform. That is, among the passive reflectors that contributed to the received reflected waveform the K passive reflectors with the best SNR may be selected for forming the K passive reflectors of the determined position feature set.

In case an integer number M of passive reflectors that contributed to the received reflected waveform of the transmitted radio signal is smaller than the K passive reflectors, the following may be true. The determined position feature set comprises relative position information of the position of the device with regard to the M passive reflectors and reflector type information of each of the M passive reflectors, wherein the device is configured to zero pad the rest of the determined position feature set. This allows functioning of the positioning by the device in case the device is at a position in the indoor environment, at which less than K passive reflectors of the indoor environment contribute to the reflected waveform of the radio signal transmittable by the device, wherein the reflected waveform may be received by the device. That is, the device may determine a position feature set in case the device detects less than K passive reflectors (i.e. passive reference points) of the indoor environment.

In an implementation form of the first aspect, the device is configured to transmit a radar signal as the radio signal.

The device may comprise a radar module for transmitting the radar signal. Optionally, the radio signal may be a frequency-modulated continuous wave (FMCW) radar signal. For example, the radar signal may be a 60GHz FMCW radar signal or a 77GHz FMCW radar signal. In an implementation form of the first aspect, the device is configured to transmit, as the radio signal, a cellular communication signal to a base station.

That is, the radio signal may be a cellular communication signal (e.g. an uplink sounding signal or an uplink data signal) which is transmitted by the device to a base station. In this case, the device may be referred to as “terminal device” or “terminal”. Optionally, when the device is configured to transmit the cellular communication signal using orthogonal frequency-division multiplexing (OFDM) modulation, the device (e.g. a receiver or receiver side of the device) may be configured to perform self-interference cancellation (SIC) with regard to a reflected waveform of the cellular communication signal in order to suppress self-interference. The device may be a terminal device. The device may be configured to be triggered by a base station to transmit the radio signal.

In an implementation form of the first aspect, the integer number K is equal to at least three or at least four.

The database comprising the plurality of position feature sets may be generated (pre-generated) by measuring for each of a plurality of positions (optionally each position) in the indoor environment the relative position information of the respective position to nearby passive reflectors, down-selecting the nearby passive reflectors to K passive reflectors, grouping the relative position information of the K passive reflectors and the reflector type information of the K passive reflectors as a position feature set for the respective position and storing the position feature set for the respective position in association with the respective position in the database.

Before grouping the relative position information of the K passive reflectors and the reflector type information of the K passive reflectors as a position feature set for the respective position, the relative position information of the K passive reflectors may be sorted. For example, the sorting criteria may be based on the relative position information. The sorting criteria may be conducted or performed per reflector type.

The database may be generated by performing physical measurements in the (real) indoor environment and/or performing virtual measurements using geometry models of the indoor environment in a computer simulation.

The size of the database may be determined by the positioning resolution and the size of the indoor environment (i.e. area of the indoor environment). In an implementation form of the first aspect, the device comprises a data storage and is configured to store the database in the data storage.

In other words, the database may be stored in a data storage of the device. The data storage may be a removable data storage. For example, the removable data storage may be a memory card (e.g. SD card or TF card) or a USB flash drive. Any other known removable data storage may be used. The data storage storing the database allows the device to autonomously determine the position of the device. In this case, the device may be configured to search the database (e.g. being stored in the device) for a position feature set whose relative position information has the smallest mean square error (smallest MSE) with respect to the relative position information of the determined position feature set, and determine the position associated with the searched position feature set of the database as the position of the device. That is, when the position feature set of the database, which comprises relative position information having the smallest mean square error with respect to the relative position information of the determined position feature set, is found, the position associated with this found position feature set of the database may be determined as the position of the device. In other words, the device may be configured to search the database for a position feature set that is most similar to the determined position feature set and determine the position associated with the position feature set being most similar to the determined position feature set as the position of the device. That is, the device may be configured to search the database for a position feature set that is closest or is the best match to the determined position feature set and determine the position associated with the position feature set being closest or the best match to the determined position feature set as the position of the device.

In an implementation form of the first aspect, the device is configured to compare the determined position feature set with the database by transmitting a query message comprising the determined position feature set to a remote server comprising the database. The device may be configured to determine the position of the device in the environment by receiving a message comprising the position of the device in response to transmitting the query message.

In other words, the database may be remotely stored in a server (i.e. remote server) and the device may compare the determined position feature set with the database (i.e. the entries of the database) by transmitting a query message comprising the determined position feature set to the server comprising or storing the database. For example, the database may be stored in a hard-disk of the server. For this, the device may be configured to use communication protocols to access the remote server and, thus, the database stored in the remote server. The server may be referred to as data server. Thus, the device may receive from the server, in response to transmitting the query message from the device to the server, the position of the device. In other words, when the database is stored in a remote server, the device may be configured to report the determined position feature set to the server using communication protocols (e.g. using a message such as a query message). The server may compute or determine the position of the device, using the database, and indicate the position of the device to the device. The term “inquiry message” may be used as a synonym for the term “query message”. The aforementioned searching of the database may also be performed in the server for comparing the position feature set of the query message with the entries of the database. The position associated with the position feature set of the database that is most similar to the position feature set of the query message may be transmitted by the server to the device as the position of the device.

Alternatively or additionally, the device may be configured to search the database (e.g. being stored in the device) for a position feature set whose relative position information has the smallest mean square error with respect to the relative position information of the determined position feature set, and determine the position associated with the searched position feature set of the database as the position of the device.

In an implementation form of the first aspect, the device is configured to move from a first position to a second position in the environment. The device may be configured to transmit at the second position a radio signal carrying a query message comprising the determined position feature set that is determined with regard to the first position of the device. Further, the device may be configured to receive a reflected waveform of the transmitted radio signal carrying the query message, and determine, using the received reflected waveform, a position feature set for the second position.

For example, the device may be configured to transmit at the second position an uplink data signal as the radio signal carrying the query message, wherein the query message comprises the determined position feature set determined with regard to the first position of the device.

In an implementation form of the first aspect, the device comprises one or more antenna lenses configured to direct the radio signal transmitted by the device in a direction of the passive reflectors of the indoor environment.

An antenna enhanced by an antenna lens may be referred to as lens antenna. For example, the passive reflectors may be arranged at a ceiling of the indoor environment. The device may comprise one or more antenna lenses configured to direct the radio signal transmitted by the device in a direction of the ceiling. That is, the one or more antenna lenses may be arranged at the device such that they face towards the ceiling. Optionally, the one or more antenna lenses are configured to direct the radio signal in a range between -60° and +60° around the normal vector of the respective antenna lens with regard to the ceiling. This reduces co-channel interferences from other devices, in case more than one device according to the first aspect are present in the indoor environment. Namely, each device may transmit the radio signal in the direction of the ceiling by using one or more antenna lenses.

In an implementation form of the first aspect, the database is associated with an ID, and the device is configured to use the database only in case the ID is valid for the indoor environment.

For example, the database may be associated to a room ID. When the device is about to move from one room (as the indoor environment) to another room (as the new indoor environment), the device may be configured to predict or determine, using a currently determined position (currently determined position information), such a room change. The device may be configured to use a database of the plurality of position feature sets that is associated with an ID for the respective indoor environment (e.g. room). The database associated with an ID for the respective indoor environment comprises the plurality of position feature sets that have been pre-generated for the respective indoor environment. In other words, the database associated with an ID for the respective indoor environment comprises the plurality of position feature sets that allows the device to perform positioning in the respective indoor environment. When changing the indoor environment (e.g. changing a room), the device may be configured to use the database associated with the ID of the new indoor environment (e.g. new room) upon determining or predicting that the device changes the indoor environment.

In an implementation form of the first aspect, the device is a robot, a helmet or a mobile phone.

The robot may be an autonomous mobile robot (AMR). The helmet may be an intelligent helmet. The device may be a part of a robot, a helmet or a mobile phone. For example, the device may be a component or module of the robot, helmet or mobile phone. The device may be or may be part of any end device or user end device. The device may be configured to move. For example, the device may be a vehicle or may be part of a vehicle.

In an implementation form of the first aspect, the device is configured to determine the position feature set by computing, based on the received reflected waveform, a channel impulse response (CIR) and determining, in the computed CIR, peaks caused by passive reflectors that contributed to the received reflected waveform.

A CIR peak may be caused by a passive reflector or by an object or entity that is not a passive reflector, such as walls, people, furniture etc. of the indoor environment. The device may be configured to classify whether a peak of the computed CIR is a peak caused by a passive reflector of the passive reflectors of the indoor environment or a peak caused by an object or entity of the indoor environment, which is not a passive reflector of the passive reflectors. The device may be configured to ignore peaks of the computed CIRthat are caused by one or more objects or entities of the indoor environment, which are not one or more passive reflectors of the passive reflectors of the environment. In other words, for determining the position of the device the device may ignore peaks of the computed CIR that are not caused by passive reflectors.

The device may comprise a baseband processor for determining, in the computed CIR, the peaks caused by passive reflectors that contributed to the received reflected waveform. For example, the device (e.g. the baseband processor) may be configured to down-convert, digitalize and process the received reflected waveform of the transmitted radio signal. For this, the device (e.g. baseband processor) may be configured to apply or perform channel estimation with regard to the reflected waveform. This generates for the reflected waveform a channel impulse response (CIR). The generated or computed CIR comprises contributions of reflection gains (i.e. peaks) of nearby passive reflectors at different delays. The nearby passive reflectors are nearby the respective position of the device. The CIR may further comprise contributions of reflection gains from other scatters within the indoor environment, which are significantly weaker compared to the reflections gains (i.e. peaks) caused by the nearby passive reflectors. The device (e.g. baseband processor) may be configured to determine or detect the peaks caused by passive reflectors that contributed to the received reflected waveform by comparing the reflection gains with predefined thresholds.

In an implementation form of the first aspect, the device is configured to determine a delay of each peak of the determined peaks and translate the delay of the respective peak into distance information of the position of the device with regard to the respective passive reflector that caused the respective peak. In addition or alternatively, the device may be configured to perform beamforming of each peak of the determined peaks and compute angle information of the position of the device with regard to the respective passive reflector that caused the respective peak.

The distance information may comprise or may be distances from the device to the passive reflectors that caused the determined peaks of the CIR, i.e. which contributed to the received reflected waveform. Thus, the distance information may be a feature of the position feature set that may be determined using the received reflected waveform. In addition or alternatively, the device may be configured to perform angle of arrival (AOA) estimation on each peak of the determined peaks to compute the angle information of the position of the device with regard to the respective passive reflector that caused the respective peak. The angle information may be a feature of the position feature set that may be determined using the received reflected waveform. In an implementation form of the first aspect, the device is configured to compute, for each peak of the determined peaks, a radar-cross-section (RCS) of the respective passive reflector that caused the respective peak by computing a transmission power to received power ratio for the respective peak.

For example, the device may be configured to compute, for each peak of the determined peaks, the RCS by using the following equation: wherein

PT corresponds to the transmission power, PR corresponds to the received power of a respective CIR peak and X is the wavelength of the radio signal. R is the distance information of the position of the device with regard to the respective passive reflector that caused the respective CIR peak (e.g. measured distance or range from the position of the device to the respective passive reflector) and o is the RCS of the respective passive reflector that cause the respective CIR peak. The characterized RCS of a spherical metal reflector and the characterized RCS of a trihedral comer reflector may be as follows:

_ 4?ra⁴

^trihedral ~ ₃^₂ ’ wherein d is the diameter of the sphere and a is the side length of the trihedral.

The device may be configured to use the determined RCS for each of the passive reflectors that contributed to the received reflected waveform for classifying the respective passive reflectors among the at least two passive reflectors types. This allows the device to generate or determine the reflector type information as a feature of the position feature set that may be determined using the received reflected waveform.

In an implementation form of the first aspect, the device comprises one or more linear dual-polarized antennas configured to transmit the radio signal and receive the reflected waveform of the transmitted radio signal. The device may be configured to compute, for each peak of the determined peaks, polarimetry features of the respective passive reflector that caused the respective peak by computing a 2x2 scattering matrix for the respective peak. The one or more antennas may be separate antennas or part of an antenna array. The device may be configured to compute, for the respective peak, relative phase information among polarization antenna pairs as polarimetry features of the passive reflector that caused the respective peak by using the 2x2 scattering matrix computed for the respective peak. In that case, the device may be configured to used relative phase information among polarization antenna pairs (i.e. V-H, V-V, H-H, H-V) to improve the accuracy of classifying the passive reflectors that contributed to the received reflected waveform (i.e. determining the reflector type information of the passive reflectors).

In an implementation form of the first aspect, the device is configured to classify, for each peak of the determined peaks, the reflector type of the respective passive reflector that caused the respective peak using the RCS and/or polarimetry features of the respective passive reflector.

In order to achieve the device according to the first aspect of the disclosure, some or all of the implementation forms and optional features of the first aspect, as described above, may be combined with each other.

A second aspect of the disclosure provides a method for determining a position of a device in an indoor environment. The environment comprises passive reflectors of at least two reflector types. The method comprises transmitting, by the device, a radio signal in the environment; receiving, by the device, a reflected waveform of the transmitted radio signal; and determining, by the device, a position feature set using the received reflected waveform. Further, the method comprises determining the position of the device in the environment by comparing the determined position feature set with a database comprising a plurality of position feature sets. Each of the plurality of position feature sets is associated with a different position in the environment. The determined feature set comprises relative position information of the position of the device with regard to K passive reflectors and reflector type information of each of the K passive reflectors. K is an integer number greater than or equal to three.

In an implementation form of the second aspect, the step of determining the position of the device in the environment by comparing the determined position feature set with the database comprising a plurality of position feature sets comprises: searching, by the device, the database for a position feature set whose relative position information has the smallest mean square error with respect to the relative position information of the determined position feature set, and determining the position associated with the searched position feature set as the position of the device. In an implementation form of the second aspect, the step of determining the position of the device in the environment by comparing the determined position feature set with the database comprising a plurality of position feature sets comprises: transmitting, by the device, a query message comprising the determined position feature set to a remote server comprising the database, and receiving, by the device, from the remote server a message comprising the position of the device in response to the query message.

The above description of the device according to the first aspect is correspondingly valid for the method of the second aspect.

Optionally, the device configured to perform the respective steps of the method is the device according to the first aspect of the disclosure.

In an implementation form of the second aspect, the relative position information of the determined position feature set comprises distance information and/or angle information of the position of the device with regard to the K passive reflectors of the determined position feature set.

In an implementation form of the second aspect, the method comprises transmitting, by two or more antennas of the device, the radio signal and receiving, by the two or more antennas the reflected waveform of the transmitted radio signal. The relative position information of the determined position feature set may comprise the angle information of the position of the device with regard to the K passive reflectors of the determined position feature set.

In an implementation form of the second aspect, each position feature set of the database comprises the relative position information of the position, associated with the respective position feature set, with regard to K passive reflectors of the passive reflectors of the environment, and the reflector type information of each of the K passive reflectors.

In an implementation form of the second aspect, the relative position information of each position feature set of the database comprises distance information and/or angle information of the position, associated with the respective position feature set, with regard to the K passive reflectors of the respective position feature set.

In an implementation form of the second aspect, the method comprises measuring, by the device, propagation parameters of the received reflected waveform and translating, by the device, the propagation parameters into relative position information of the position of the device with regard to passive reflectors that contributed to the received reflected waveform.

In an implementation form of the second aspect, the method comprises determining, by the device, the reflector type information of each of passive reflectors that contributed to the received reflected waveform using one or more pre-characterized reflection coefficients of the at least two reflector types. The one or more pre-characterized reflection coefficients may comprise a radar-cross-section (RCS) and/or polarimetry features.

In an implementation form of the second aspect, the method comprises computing, by the device, for passive reflectors that contributed to the received reflected waveform the relative position information of the position of the device with regard to the passive reflectors, and the reflector type information of each of the passive reflectors. The method may comprise selecting, by the device, according to the computed relative position information among the passive reflectors that contributed to the received reflected waveform the K passive reflectors of the determined position feature set.

In an implementation form of the second aspect, the method comprises transmitting, by the device, a radar signal as the radio signal.

In an implementation form of the second aspect, the method comprises transmitting, by the device, as the radio signal a cellular communication signal to a base station.

In an implementation form of the second aspect, the integer number K is equal to at least three or at least four.

In an implementation form of the second aspect, the device comprise a data storage and the method comprises storing, by the device, the database in the data storage.

In an implementation form of the second aspect, the method comprises comparing, by the device, the determined position feature set with the database by transmitting a query message comprising the determined position feature set to a remote server comprising the database. The method may comprise determining, by the device, the position of the device in the environment by receiving a message comprising the position of the device in response to transmitting the query message.

In an implementation form of the second aspect, the device moves from a first position to a second position in the environment. The method may comprise transmitting, by the device, at the second position a radio signal carrying a query message comprising the determined position feature set that is determined with regard to the first position of the device. Further, the method may comprise receiving, by the device, a reflected waveform of the transmitted radio signal carrying the query message. Furthermore, the method may comprise determining, by the device, using the received reflected waveform a position feature set for the second position.

In an implementation form of the second aspect, the method comprises directing, by one or more antenna lenses of the device, the radio signal transmitted by the device in a direction of the passive reflectors of the indoor environment.

In an implementation form of the second aspect, the database is associated with an ID, and the method comprises using, by the device, the database only in case the ID is valid for the indoor environment.

In an implementation form of the second aspect, the device is a robot, a helmet or a mobile phone.

In an implementation form of the second aspect, the method comprises determining, by the device, the position feature set by computing, based on the received reflected waveform, a channel impulse response (CIR) and determining, in the computed CIR, peaks caused by passive reflectors that contributed to the received reflected waveform.

In an implementation form of the second aspect, the method comprises determining, by the device, a delay of each peak of the determined peaks and translating, by the device, the delay of the respective peak into distance information of the position of the device with regard to the respective passive reflector that caused the respective peak. In addition or alternatively, the method may comprise performing, by the device, beamforming of each peak of the determined peaks and computing, by the device, angle information of the position of the device with regard to the respective passive reflector that caused the respective peak.

In an implementation form of the second aspect, the method comprises computing, by the device, for each peak of the determined peaks a radar-cross-section (RCS) of the respective passive reflector that caused the respective peak by computing a transmission power to received power ratio for the respective peak.

In an implementation form of the second aspect, the method comprises transmitting, by one or more linear dual-polarized antennas of the device, the radio signal and receiving, by the one or more linear dual-polarized antennas, the reflected waveform of the transmitted radio signal. The method may comprise computing, by the device, for each peak of the determined peaks polarimetry features of the respective passive reflector that caused the respective peak by computing a 2x2 scattering matrix for the respective peak.

In an implementation form of the second aspect, the method comprises classifying, by the device, for each peak of the determined peaks the reflector type of the respective passive reflector that caused the respective peak using the RCS and/or polarimetry features of the respective passive reflector.

The method of the second aspect and its implementation forms and optional features achieve the same advantages as the device of the first aspect and its respective implementation forms and respective optional features.

In order to achieve the method according to the second aspect of the disclosure, some or all of the implementation forms and optional features of the second aspect, as described above, may be combined with each other.

A third aspect of the disclosure provides a system of three or more passive reflectors of at least two reflector types. The passive reflectors are arranged in an indoor environment such that any three passive reflectors of the three or more passive reflectors do not lie in the same line, a triangle formed by any three passive reflectors of the three or more passive reflectors is not isosceles, and a symmetry line of one pair does not pass through the symmetry point of another pair with regard to any two pairs of the three or more passive reflectors, wherein each pair of the any two pairs comprises maximal one common passive reflector.

In other words, the passive reflectors are arranged in the indoor environment such that all the above three conditions are met or true.

Radio signals or waveforms reflected from the passive reflectors may be differentiated from other scatters of the indoor environment based on the radar-cross-section (RCS) and polarimetry features of the passive reflectors, which may be characterized beforehand (i.e. they may be pre-characterized).

In an implementation form of the third aspect, the three or more passive reflectors are configured to be arranged at a ceiling of the indoor environment.

In an implementation form of the third aspect, the at least two reflector types comprise one or more metal reflectors and/or one or more dielectric reflectors. The description of the system of the third aspect, e.g. of the passive reflectors of the system, may be correspondingly valid for the passive reflectors described above with regard to the device of the first aspect and the method of the second aspect.

The above description of the device according to the first aspect may be correspondingly valid for the system of three or more passive reflectors according to the third aspect. For example, the above description of passive reflectors being a part of the description of the device according to the first aspect may be correspondingly valid for the passive reflectors of the system according to the third aspect.

The system of the third aspect and its implementation forms and optional features achieve the same advantages as the device of the first aspect and its respective implementation forms and respective optional features.

In order to achieve the system according to the third aspect of the disclosure, some or all of the implementation forms and optional features of the third aspect, as described above, may be combined with each other.

A fourth aspect of the disclosure provides a method for arranging three or more passive reflectors of at least two reflectors types. The method comprises arranging the passive reflectors in an indoor environment such that: any three passive reflectors of the three or more passive reflectors do not lie in the same line, a triangle formed by any three passive reflectors of the three or more passive reflectors is not isosceles, and a symmetry line of one pair does not pass through the symmetry point of another pair with regard to any two pairs of the three or more passive reflectors, wherein each pair of the any two pairs comprises maximal one common passive reflector.

The above description of the system according to the third aspect is correspondingly valid for the method according to the fourth aspect.

The three or more passive reflectors of at least two reflectors may be implemented according to the three or more passive reflectors of at least two reflectors of the system according to the third aspect.

In an implementation form of the fourth aspect, the method comprises arranging the three or more passive reflectors at a ceiling of the indoor environment. The method of the fourth aspect and its implementation forms and optional features achieve the same advantages as the device of the first aspect and its respective implementation forms and respective optional features.

In order to achieve the method according to the fourth aspect of the disclosure, some or all of the implementation forms and optional features of the fourth aspect, as described above, may be combined with each other.

A fifth aspect of the disclosure provides a database for positioning in an indoor environment. The environment comprises passive reflectors of at least two reflector types. The database comprises a plurality of position feature sets each being associated with a different position in the environment. Each position feature set of the database comprises relative position information of the position, associated with the respective position feature set, with regard to K passive reflectors of the passive reflectors of the environment and reflector type information of each of the K passive reflectors. K is an integer number greater or equal to three.

The size of the database may be determined by the positioning resolution and the size of the indoor environment (i.e. area of the indoor environment). The description of the database of the fifth aspect may be correspondingly valid for the database usable by the device of the first aspect and the method of the second aspect. The description of the device according to the first aspect, e.g. the description of the database usable by the device according to the first aspect, may be correspondingly valid for the database of the fifth aspect.

The database of the fifth aspect and its implementation forms and optional features achieve the same advantages as the device of the first aspect and its respective implementation forms and respective optional features.

In order to achieve the database according to the fifth aspect of the disclosure, some or all of the implementation forms and optional features of the fifth aspect, as described above, may be combined with each other.

A sixth aspect of the disclosure provides a method for generating a database for positioning in an indoor environment. The environment comprises passive reflectors of at least two reflector types. The database comprises a plurality of position feature sets each being associated with a different position in the environment. Each position feature set of the database comprises relative position information of the position, associated with the respective position feature set, with regard to K passive reflectors of the passive reflectors of the environment and reflector type information of each of the K passive reflectors. K is an integer number greater or equal to three. The method comprises measuring for a plurality of positions in the indoor environment the relative position information of the respective position to nearby passive reflectors. Further, the method comprises down-selecting, for each of the plurality of positions, the nearby passive reflectors to K passive reflectors. Furthermore, the method comprises grouping, for each of the plurality of positions, the relative position information of the K passive reflectors and the reflector type information of the K passive reflectors as a respective position feature set. Moreover, the method comprises storing, for each of the plurality of positions, the respective position feature set in association with the respective position of the plurality of positions in the database.

The database may be the database according to the fifth aspect. The above description of the database according to the fifth aspect is correspondingly valid for the method according to the sixth aspect.

Measuring the relative position information of the respective position to nearby passive reflectors may comprise performing physical measurements in the (real) indoor environment and/or virtual measurements using geometry models of the indoor environment in a computer simulation. The method of the sixth aspect and its implementation forms and optional features achieve the same advantages as the device of the first aspect and its respective implementation forms and respective optional features.

In order to achieve the method according to the sixth aspect of the disclosure, some or all of the implementation forms and optional features of the sixth aspect, as described above, may be combined with each other.

A seventh aspect of the disclosure provides a non-transitory storage medium storing the database of the fifth aspect. An eighth aspect of the disclosure provides a computer readable storage medium storing the database of the fifth aspect.

The non-transitory storage medium of the seventh aspect and the computer readable storage medium of the eighth aspect each achieve the same advantages as the device of the first aspect and its respective implementation forms and respective optional features.

It has to be noted that all devices, elements, units and means described in the present application could be implemented in software or hardware elements or any kind of combination thereof. All steps which are performed by the various entities described in the present application as well as the functionalities described to be performed by the various entities are intended to mean that the respective entity is adapted to or configured to perform the respective steps and functionalities. Even if, in the following description of specific embodiments, a specific functionality or step to be performed by external entities is not reflected in the description of a specific detailed element of that entity which performs that specific step or functionality, it should be clear for a skilled person that these methods and functionalities can be implemented in respective software or hardware elements, or any kind of combination thereof.

BRIEF DESCRIPTION OF DRAWINGS

The above described aspects and implementation forms of the present disclosure will be explained in the following description of specific embodiments in relation to the enclosed drawings, in which

Figure 1 shows a device according to an embodiment of the present disclosure for positioning in an indoor environment, the environment comprising passive reflectors of at least two reflector types;

Figures 2 and 3 each show an example of the device of Figure 1;

Figure 4 shows a block diagram of an example of the device of Figure 1 ; Figure 5 shows a method according to an embodiment of the present disclosure for determining a position of a device in an indoor environment, the environment comprising passive reflectors of at least two reflector types;

Figure 6 shows an example of a part of the method of Figure 5;

Figure 7 shows an example of a channel impulse response;

Figures 8 and 9 each show an example of a part of the method of Figure 5;

Figure 10 shows an example of a part of the method of Figure 5;

Figure 11 shows a method according to an embodiment of the present disclosure for determining a position of a device in an indoor environment, the environment comprising passive reflectors of at least two reflector types;

Figure 12 shows an example of a schematic bird’s eye view of a system of three or more passive reflectors of at least two reflector types according to an embodiment of the present disclosure;

Figure 13 shows a method for arranging three or more passive reflectors of at least two reflectors types;

Figure 14 shows a method according to an embodiment of the present disclosure for generating a database for positioning in an indoor environment, wherein the environment comprises passive reflectors of at least two reflector types; and

Figure 15 shows an example of an entry of a database according to an embodiment of the present disclosure for positioning in an indoor environment; wherein the environment comprises passive reflectors of at least two reflector types.

In the Figures, corresponding elements are labeled with the same reference sign. In the Figures, the size of elements is not necessary to scale for describing the different examples of the disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

Figure 1 shows a device according to an embodiment of the present disclosure for positioning in an indoor environment, the environment comprising passive reflectors of at least two reflector types. The device 1 of Figure 1 is an example of the device according to the first aspect of the present disclosure. The description of the device of the first aspect is correspondingly valid for the device 1 of Figure 1.

The device 1 of Figure 1 is a device for position in an indoor environment 5. That is, the device 1 is configured to determine its position (i.e. the position of the device 1) in the indoor environment. The environment 5 comprises passive reflectors 4 of at least two reflector types (i.e. of two or more reflectors types). This means at least two different reflector types are used for providing the passive reflectors 4. The number of passive reflectors 4 shown in Figure 1 is only by way of example and not limiting for the present disclosure. As shown in Figure 1, the device 1 may transmit a radio signal 2 in the environment 5. This radio signal 2 is reflected by nearby passive reflectors of the passive reflectors 4 of the environment. That is, passive reflectors that are arranged near the position of the device 1 such that the transmitted radio signal 2 arrives at the passive reflectors and, thus, is reflected by each of the passive reflectors contribute to a reflected waveform 3 of the transmitted radio signal 2. The device 1 is configured to receive the reflected waveform 3 of the transmitted radio signal 2. The device is configured to determine, using the received reflected waveform 3, a position feature set. Furthermore, the device 1 is configured to determine a position of the device 1 in the environment 5 by comparing the determined position feature set with a database comprising a plurality of position feature sets. Each of the plurality of position feature sets is associated with a different position in the environment 5. The determined position feature set comprises relative position information of the position of the device 1 with regard to K passive reflectors and reflector type information of each of the K passive reflectors. K is an integer number greater than or equal to three. Optionally, K is equal to at least three or at least four.

Figures 2 and 3 each show an example of the device of Figure 1. As shown in Figure 2, the device 1 may be or may be part of a robot. The indoor environment 5 may be an indoor space, such as a room of a building. The robot may be configured to move in the indoor environment 5 and, thus, the device 1 may be configured to move in the environment 5. As shown, the passive reflectors 4 of the indoor environment 5 may for example be arrange or positioned at a ceiling of the indoor environment 5 (e.g. room). For this, the device 1 may be configured to transmit a radio signal 2 in the direction of the ceiling and, thus, in the direction of the passive reflectors 4.

As shown in Figure 3, for this the device 1 may comprise one or more antenna lenses 7 configured to direct the radio signal 2 transmitted by the device 1 in a direction of the passive reflectors 4 that are arranged at a ceiling 6 of the indoor environment. That is, the one or more antenna lenses 7 may be arranged at the device 1 such that they face towards the ceiling 6. Optionally, the one or more antenna lenses 7 are configured to direct the radio signal 2 in a range between e.g. -60° and +60° (a = 60°) around the normal vector 9 of the respective antenna lens 7 with regard to the ceiling 6. This reduces co-channel interferences from other devices, in case more than one of the device 1 is present in the environment. Figure 3 indicates this by showing two devices 1 each configured to transmit radio signals in the direction of the ceiling by using one or more antenna lenses 7. In the area between the two devices 1, indicated by the double arrow, no radio signals are transmitted for performing positioning by the respective device 1 due to the one or more antenna lenses 7. Thus, this reduces channel interferences between the two devices 1 shown in Figure 3. The number of passive reflectors 4 and devices 1 of Figure 3 is only by way of example and does not limit the present disclosure. The passive reflectors are different in size to exemplarily indicate two different types of passive reflectors. Thus, as shown in Figures 2 and 3, the passive reflectors may be pre-installed within the indoor environment. One example is to hang the passive reflectors 4 below the ceiling 6 while the device 1 is positioned on the ground. The device 1 may be configured to scan and detect the passive reflectors 4 by facing its one or more antennas towards the ceiling. Detecting passive reflectors may be understood as receiving a reflected waveform (of a radio signal 2 transmitted by the device), to which the passive reflectors contributed.

Figure 4 shows a block diagram of an example of the device of Figure 1. As indicated in Figure 4 the device may comprise a processor la, a transceiver lb and at least one antenna 1c. The processor la may be or may comprise a baseband processor. The transceiver lb may be a radio frequency (RF) transceiver. The transceiver lb and the antenna 1c may be configured to transmit a radio signal 2 in the indoor environment and receive a reflected waveform 3 of the transmitted radio signal 2. The processor la may be configured to process the received reflected waveform 3 for performing positioning in the environment, i.e. for determining the position of the device 1 in the environment.

According to an example, the device 1 comprises one antenna 1c. The device 1 (e.g. the processor la) may be configured to determine distance information of the position of the device 1 with regard to the K passive reflectors of the determined position feature set. Further, the device 1 (e.g. the processor la) may be configured to determine reflector type information of each of the K passive reflectors using a radar-cross-section (RCS) as a pre-characterized reflection coefficient of the at least two reflector types of the passive reflectors 4 arranged in the indoor environment 5. That is, the device 1 (e.g. the processor la) may be configured to determine the reflector type information of each of passive reflectors that contributed to the received reflected waveform 3 using the RCS of the at least two reflector types. Thus, the device 1 (e.g. the processor la) may be configured to determine the position feature set using distance information of the position of the device with regard to the passive reflectors that contributed to the received reflected waveform 3 and the RCS as a pre-characterized reflection coefficient of the at least two reflector types.

According to an example, the device 1 comprises one linear dual-polarized antenna 1c. The device 1 (e.g. the processor la) may be configured to determine distance information of the position of the device with regard to the K passive reflectors of the determined position feature set. Further, the device 1 (e.g. the processor la) may be configured to determine reflector type information of each of the K passive reflectors using a radar-cross-section (RCS) and polarimetry features as pre-characterized reflection coefficients of the at least two reflector types of the passive reflectors 4 arranged in the indoor environment 5. That is, the device 1 (e.g. the processor la) may be configured to determine the reflector type information of each of passive reflectors that contributed to the received reflected waveform 3 using the RCS and polarimetry features of the at least two reflector types. Thus, the device 1 (e.g. the processor la) may be configured to determine the position feature set using distance information of the position of the device with regard to the passive reflectors contributed to the received reflected waveform 3 as well as RCS and polarimetry features as pre-characterized reflection coefficients of the at least two reflector types.

According to an example, the device 1 comprises two or more antennas 1c. The device 1 (e.g. the processor la) may be configured to determine distance information of the position of the device with regard to the K passive reflectors of the determined position feature set. In addition, the device 1 (e.g. the processor la) may be configured to determine angle information of the position of the device with regard to the K passive reflectors of the determined position feature set. For example, the device 1 (e.g. the processor la) may be configured to detect as angle information an angle of arrival (AOA) by using beam forming. The term “beam steering” may be used as a synonym for the term “beam forming”. Further, the device 1 (e.g. the processor la) may be configured to determine reflector type information of each of the K passive reflectors using a radar-cross-section (RCS) as a pre-characterized reflection coefficient of the at least two reflector types of the passive reflectors 4 arranged in the indoor environment 5. That is, the device 1 (e.g. the processor la) may be configured to determine the reflector type information of each of passive reflectors that contributed to the received reflected waveform 3 using the RCS of the at least two reflector types. Thus, the device 1 (e.g. the processor la) may be configured to determine the position feature set using distance information and angle information of the position of the device with regard to the passive reflectors contributed to the received reflected waveform 3 and RCS as a pre-characterized reflection coefficient of the at least two reflector types.

According to an example, the device 1 comprises two or more linear dual-polarized antenna 1c. The device 1 (e.g. the processor la) may be configured to determine distance information of the position of the device with regard to the K passive reflectors of the determined position feature set. In addition, the device 1 (e.g. the processor la) may be configured to determine angle information of the position of the device with regard to the K passive reflectors of the determined position feature set. For example, the device 1 (e.g. the processor la) may be configured to detect as angle information an angle of arrival (AOA) by using beam forming. Further, the device 1 (e.g. the processor la) may be configured to determine reflector type information of each of the K passive reflectors using a radar-cross-section (RCS) and polarimetry features as pre-characterized reflection coefficients of the at least two reflector types of the passive reflectors 4 arranged in the indoor environment 5. That is, the device 1 (e.g. the processor la) may be configured to determine the reflector type information of each of passive reflectors that contributed to the received reflected waveform 3 using the RCS and polarimetry features of the at least two reflector types. Thus, the device 1 (e.g. the processor la) may be configured to determine the position feature set using distance information and angle information of the position of the device with regard to the passive reflectors contributed to the received reflected waveform 3 as well as RCS and polarimetry features as pre-characterized reflection coefficients of the at least two reflector types.

Optionally, in any of the aforementioned examples with regard to one or more antennas 1c of the device 1, the one or more antennas 1c may be enhanced or equipped by an antenna lens for directing the radio signal 2 in a direction (i.e. focusing the energy of the radio signal towards the direction). For example, this allows directing the radio signal 2 transmitted by the one or more antennas 1c of the device towards a ceiling of a room, in case the passive reflectors 4 are arranged at the ceiling. That is, this allows focusing the energy of the transmitted radio signal 2 towards the ceiling.

In case the device comprises two or more antennas 1c, the antennas may be separate antennas or part of an antenna array. The device 1 may be configured to apply beamforming techniques for steering the sensing direction so that the device is configured to determine or measure angle information in addition to distance information as relative position information of the position of the device with regard to passive reflectors. This allows distance information and angle information to be part of the determined position feature set.

In the following, method steps that may be performed by the device 1 of any one of Figures 1 to 4 for determining the position of the device 1 in the indoor environment 5 are exemplarily described with regard to Figures 5 to 11.

Figure 5 shows a method according to an embodiment of the present disclosure for determining a position of a device in an indoor environment, the environment comprising passive reflectors of at least two reflector types. The method of Figure 5 is an example of the method according to the second aspect of the disclosure. The above description of the method of the second aspect is correspondingly valid for the method of Figure 5.

The method of Figure 5 is a method for determining a position of a device in an indoor environment. The device may be the device 1 of any one of Figures 1 to 4. The environment comprises passive reflectors of at least two reflector types. The description of passive reflectors described with regard to the device according to the first aspect and the description of passive reflectors of the system according to the third aspect is correspondingly valid for the passive reflectors of the indoor environment. In a first step 51, the method comprises transmitting a radio signal in the environment. In a next step 52, the method comprises receiving a reflected waveform of the transmitted radio signal. In a step 53 following the step 52, the method comprises determining a position feature set using the received reflected waveform. Further, in a step 54 following the step 53 the method comprises determining the position of the device in the environment by comparing the determined position feature set with a database comprising a plurality of position feature sets. Each of the plurality of position feature sets of the database is associated with a different position in the environment. The determined feature set comprises relative position information of the position of the device with regard to K passive reflectors (K being an integer number greater than or equal to three) and reflector type information of each of the K passive reflectors.

The steps 51, 52 and 53 of the method of Figure 5 may be performed by the device. The step 54 of the method of Figure 5 may be performed by the device, as exemplarily described with regard to Figure 8. Alternatively, the step 54 of the method of Figure 5 may be indirectly performed by the device, as exemplarily described with regard to Figure 9. The device may be the device 1 of any one of Figures 1 to 4.

The transceiver lb and the at least one antenna 1c of the device 1 of Figure 4 may be configured to perform the steps 51 and 52 of the method of Figure 5. The processor la of the device 1 of Figure 4 may be configured to perform the step 53 and optionally the step 54 of the method of Figure 5. Optionally, the transceiver lb and the at least one antenna 1c of the device 1 of Figure 4 may be configured to perform or contribute to performing the step 54 of the method of Figure 5.

Figure 6 shows an example of a part of the method of Figure 5. Namely, Figure 6 shows details of the step 53 of the method of Figure 5 according to an example of the disclosure. In other words, Figure 6 shows a method or process for determining a position feature set using the received reflected waveform. In a first step 61, the method of Figure 6 comprises computing, based on the received reflected waveform, a channel impulse response (CIR). In a next step 62, the method comprises determining, in the computed CIR, peaks caused by passive reflectors that contributed to the received reflected waveform. With regard to the CIR, Figure 7 shows an example of a CIR.

The graph of Figure 7 indicates on the vertical axis (e.g. y-axis) a gain between 0 and 1, i.e. between 0% and 100%, and on the horizontal axis (e.g. x-axis) path delays (e.g. To, Ti, 12 and 13) in nanoseconds (ns). For example, for sub-meter positioning, the bandwidth of the transmitted radio signal may be greater than 1 GHz and, thus, the path delay may be in the range of nanoseconds (ns). As shown in Figure 7, the computed CIR comprises the contributions of the reflection gains of nearby passive reflectors at different delays. The passive reflectors are nearby in that they are arranged with regard to the position of the device such that the radio signal transmitted by the device is reflected by the nearby reflectors, wherein the reflections contributed the reflected waveform received by the device in response to transmitting the radio signal. The peaks 10 caused by corresponding passive reflectors are indicated in Figure 7. As shown in Figure 7, the CIR comprises the contributions of the reflection gains from other scatters within the indoor environment, which are significantly weaker or smaller than the reflection gains 10 (peaks) caused by the passive reflectors of the indoor environment. The peaks caused by passive reflectors that contributed to the received reflected waveform may be determined by comparing the reflection gains with one or more predefined thresholds.

With regard to the method of Figure 6, in the step 63 following the step 62, the method comprises determining a delay of each peak of the determined peaks and translating the delay of the respective peak into distance information of the position of the device with regard to the respective passive reflector that caused the respective peak. In an optional next step 64, the method comprises performing beamforming of each peak of the determined peaks and compute angle information of the position of the device with regard to the respective passive reflector that caused the respective peak. In a next step 65 following the step 63 or the optional step 64, the method comprises computing, for each peak of the determined peaks, a radar-cross-section (RCS) of the respective passive reflector that caused the respective peak by computing a transmission power to received power ratio for the respective peak. In an optional next step 66, the method comprises computing, for each peak of the determined peaks, polarimetry features of the respective passive reflector that caused the respective peak by computing a 2x2 scattering matrix for the respective peak. In a next step 67 following the step 65 or the optional step 66, the method comprises classifying, for each peak of the determined peaks, the reflector type of the respective passive reflector that caused the respective peak using the RCS and optionally polarimetry features of the respective passive reflector. In other words, in step 67 the reflector type information of the respective passive reflector that caused the respective peak may be determined. In a next step 68, the method comprises selecting among the passive reflectors that caused the peaks of the CIR K passive reflectors, wherein K is an integer number greater than or equal to three. Optionally, K is equal to at least three or at least four (K > 3 or K > 4). For example, K may be equal to three or four (K = 3 or K = 4).

That is, among the passive reflectors that contributed to the received reflected waveform the most suitable passive reflectors may be selected as the K passive reflectors. That is, in case the device detects more than K passive reflectors, the device may be configured to down-select the detected passive reflectors to K passive reflectors. Being suitable may be determined based on the relative position information (e.g. distance information and/or angle information). In other words, a selection criteria may be based on sorted relative position information (e.g. distance) of the position of the device with regard to the passive reflectors contributing to the received reflected waveform. Alternatively or additional the selection criteria may be based on sorted signal to noise ratio (SNR) measurements for the passive reflectors that contributed to the received reflected waveform. That is, among the passive reflectors that contributed to the received reflected waveform the K passive reflectors with the best SNR may be selected for forming the K passive reflectors. In a step 69 following the step 68, the method may comprise grouping the distance information, optionally the angle information and the reflector type information of the K passive reflectors as a position feature set.

Optionally, the step 63 or the step 64 may be not part of the method of Figure 6. In case the step 63 is not part of the method, the step 64 is the next step after the step 62. Accordingly, in case the step 64 is not part of the method, the step 65 is the next step after the step 63. The step 69 may be adapted accordingly. That is, optionally, in addition to the reflector type information, the distance information or the angle information may be used for the position feature set.

Optionally, the step 65 or the step 66 may be not part of the method of Figure 6. In case the step 65 is not part of the method, the step 66 is the next step after the step 63 or step 64 (depending on whether the step 64 is part of the method). Accordingly, in case the step 66 is not part of the method, the step 67 is the next step after the step 65. The step 67 may be adapted accordingly. That is, for classifying the reflector type of the respective passive reflector that caused the respective peak the RCS or the polarimetry features of the respective passive reflector may be used.

The processor la of the device 1 of Figure 4 may be configured to perform the method of Figure 6.

Figures 8 and 9 each show an example of a part of the method of Figure 5. Namely, Figures 8 and 9 each show details of the step 54 of the method of Figure 5 according to an example of the disclosure. In other words, Figures 8 and 9 each show a method or process for determining the position of the device in the environment by comparing the determined position feature set with a database comprising a plurality of position feature sets.

In a first step 81 of the method of Figure 8, the method comprises searching the database for a position feature set whose relative position information has the smallest mean square error with respect to the relative position information of the determined position feature set. In a next step 82, the method comprises determining the position associated with the searched position feature set as the position of the device. In this case, the device performing the method of Figure 8 (e.g. the device 1 of any one of Figures 1 to 4) may comprise a data storage storing the database. That is, the database is locally provided at the device. The processor la of the device 1 of Figure 4 may be configured to perform the steps 81 and 82 of the method of Figure 8.

In a first step 91 of the method of Figure 9, the method comprises transmitting a query message comprising the determined position feature set to a remote server comprising the database. In a next step 92, the method comprises receiving a message (from the remote server), wherein the message comprises the position of the device in response to the query message. The remote server may be configured to perform the steps 81 and 82 of the method of Figure 8 using the determined position feature set of the query message. The transceiver lb and the at least one antenna 1c of the device 1 of Figure 4 may be configured to perform the steps 91 and 92 of the method of Figure 9.

In case the query message is transmitted using a radio signal, the radio signal may the radio signal for detecting nearby passive reflectors, i.e. for generating a reflected waveform that may be received (for performing positioning). Thus, when the device moves from a first position to a second position, at the second position a radio signal carrying a position feature set determined for the first position may be transmitted to the server. In addition, at the second position a reflected waveform of the same radio signal (to sense or detect nearby passive reflectors from the second position) may be received and used to determine a position feature set for the second position. That is, the reflected waveform may be used to update an upcoming passive reflectors measurement report.

Figure 10 shows an example of a part of the method of Figure 5. Namely, Figure 10 shows an example of the steps 53 and 54 of the method of Figure 10. The method of Figure 10 corresponds to the method of Figure 9. As shown, in a first step 101 the device may determine a position feature set using a received reflected waveform. This corresponds to the step 53 of the method of Figure 5. In a next step 102, the device may transmit a query message comprising the determined position feature set to a server (remote server). This corresponds to the step 91 of the method of Figure 9. The server comprises or stores the database of plurality of position feature sets. The server may receive the query message. In a next step 103, the server may determine the position of the device using the determined position feature set of the received query message. For this, the server may search the database for a position feature set whose relative position information has the smallest mean square error with respect to the relative position information of the determined position feature set. Further, the server may determine the position associated with the searched position feature set as the position of the device. In a next step 104, the server may transmit a message comprising the position of the device (i.e. the position found in the database in step 103) to the device. Thus, the device may receive the message comprising the position of the device in response to transmitting the query message.

Figure 11 shows a method according to an embodiment of the present disclosure for determining a position of a device in an indoor environment, the environment comprising passive reflectors of at least two reflector types. The method of Figure 11 is an example of the method according to the second aspect of the disclosure. The above description of the method of the second aspect is correspondingly valid for the method of Figure 11. In a first step 111, the method comprises transmitting, at a first position of the device, a radio signal. In a next step 112, the method comprises receiving a reflected waveform of the transmitted radio signal. In a step 113 following the step 112, the method comprises determining, using the received reflected waveform, a position feature set for the first position of the device. In a next step 114 the device moves or is moved from the first position in the indoor environment to a second position in the indoor environment. In a step 115 following the step 114, the method comprises transmitting, at the second position, a second radio signal carrying a query message comprising the determined position feature set to a remote server comprising the database of the plurality of position feature sets. In a next step 116, the method comprises receiving a reflected waveform of the transmitted second radio signal. In a step

117 following the step 116, the method comprises determining, using the received reflected waveform of the transmitted second radio signal, a second position feature set for the second position. In a next step 118, the method comprises receiving (from the remote server) a message comprising the position of the device in response to the query message. This position of the device is the first position of the device. The step 118 may occur before the step 116 or 117. Alternatively, the step 118 may occur at the same time as the step 116 or 117. For determining the second position of the device, the steps 115 and

118 may be repeated for the determined second position feature set. When the device moves further to other positions, respective steps of the method of Figure 11 may be performed for determining the respective further positions.

The steps 111 and 115 of the method of Figure 11 correspond to the step 51 of the method of Figure 5.

The steps 112 and 116 of the method of Figure 11 correspond to the step 52 of the method of Figure 5.

The steps 113 and 117 of the method of Figure 11 correspond to the step 53 of Figure 5. The steps 115 and 118 of the method of Figure 11 correspond to the step 54 of Figure 5 for determining the first position of the device. Thus, in the method of Figure 11 at the step 115 the step 51 of the method of Figure 5 may be performed for determining the second position of the device and at the same time a part of the step 54 of the method of Figure 5 may be performed for determining the first position of the device. The steps 115 and 118 of Figure 11 correspond to the steps 91 and 92 ofFigure 9, respectively.

The the method of Figure 11 may be performed by the device. The device may be the device 1 of any one of Figures 1 to 4.

The transceiver lb and the at least one antenna 1c of the device 1 of Figure 4 may be configured to perform the steps 111, 112, 115, 116 and 118 of the method ofFigure 11. The processor la of the device 1 of Figure 4 may be configured to perform the steps 113 and 117 of the method of Figure 11.

Figures 12 shows an example of a schematic bird’s eye view of a system of three or more passive reflectors of at least two reflector types according to an embodiment of the present disclosure. The system of Figure 12 is an example of the system according to the third aspect of the disclosure. Thus, the description of the system according to the third aspect is correspondingly valid for the system of Figure 12.

According to Figure 12, the system comprises four passive reflectors of two reflector types 4a and 4b, wherein the passive reflectors are arranged in an indoor environment. The two reflector types may be a metal reflector (e.g. spherical metal reflector(s) or trihedral comer reflector(s)) and a dielectric reflector (e.g. Luneburg lens(es)). Alternatively, the two reflector types may be two different metal reflectors or two different dielectric reflectors.

The four passive reflectors of Figure 12 are arranged in the indoor environment such that the following three conditions are met or true. Any three passive reflectors of the four passive reflectors do not lie in the same line. A triangle formed by any three passive reflectors of the four passive reflectors is not isosceles. A symmetry line of one pair does not pass through the symmetry point of another pair with regard to any two pairs of the four passive reflectors, wherein each pair of the any two pairs comprises maximal one common passive reflector. Due to the example arrangement of the four passive reflectors of two reflector types 4a and 4b of Figure 12, the device of any one of Figures 1 to 4 may determine for each position of the indoor environment a different position feature set, which improves accuracy of positioning.

Since it is sufficient to provide three (not shown in Figure 12) or four passive reflectors of two reflector types in the indoor environment for performing positioning in the indoor environment by the device of any one of Figures 1 to 4, not too many signals are reflected when transmitting a radio signal in the indoor environment. That is, increasing the number of passive reflectors and the number of passive reflector types too much may make the detection of passive reflectors and classification of the reflector type more difficult. Namely, the increased number of reflected signals from different passive reflectors may interfere with each other. Thus, the above three conditions for arranging the passive reflectors in the indoor environment are advantageous, because already a smaller number of passive reflectors (e.g. three passive reflectors or four passive reflectors) of two reflectors types arranged according to these three conditions may allow the device of any one of Figures 1 to 4 to perform positioning with a good accuracy. Optionally, more than three or more than four passive reflectors may be used, depending on the size of the indoor environment. Optionally, more than two reflector types (i.e. more than two different reflector types) may be used.

Figure 13 shows a method for arranging three or more passive reflectors of at least two reflectors types. The method of Figure 13 may be used for arranging the passive reflectors of the system of Figure 12 in the indoor environment. The description of Figure 12 is correspondingly valid for the method of Figure 13. The method of Figure 13 is an example of the method according to the fourth aspect of the disclosure. The description of the method of the fourth aspect is correspondingly valid for the method of Figure 13.

In a step 131 of the method of Figure 13, three or more passive reflectors of at least two reflector types are arranged in an indoor environment such that the following three conditions are met. Any three passive reflectors of the three or more passive reflectors do not he in the same line. A triangle formed by any three passive reflectors of the three or more passive reflectors is not isosceles. A symmetry line of one pair does not pass through the symmetry point of another pair with regard to any two pairs of the three or more passive reflectors, wherein each pair of the any two pairs comprises maximal one common passive reflector.

Figure 14 shows a method according to an embodiment of the present disclosure for generating a database for positioning in an indoor environment, wherein the environment comprises passive reflectors of at least two reflector types. The method of Figure 14 is an example of the method of the sixth aspect of the present disclosure. The description of the method of the sixth aspect is correspondingly valid for the method of Figure 14.

The method of Figure 14 is a method for generating a database for positioning in an indoor environment. The environment comprises passive reflectors of at least two reflector types. The database comprises a plurality of position feature sets each being associated with a different position in the environment. Each position feature set of the database comprises relative position information of the position, associated with the respective position feature set, with regard to K passive reflectors of the passive reflectors of the environment and reflector type information of each of the K passive reflectors. K is an integer number greater or equal to three.

As shown in Figure 14, in a first step 141, the method comprises measuring for a plurality of positions in the indoor environment the relative position information of the respective position to nearby passive reflectors. The step 141 may comprise performing physical measurements in the (real) indoor environment and/or virtual measurements using geometry models of the indoor environment in a computer simulation. In a next step 142, the method comprises down-selecting, for each of the plurality of positions, the nearby passive reflectors to K passive reflectors. In a step 143 following the step 142, the method comprises grouping, for each of the plurality of positions, the relative position information of the K passive reflectors and the reflector type information of the K passive reflectors as a respective position feature set. In a next step 144, the method comprises storing, for each of the plurality of positions, the respective position feature set in association with the respective position of the plurality of positions in the database. The step 141 may be performed for any position in the indoor environment. That is, for any position in the indoor environment the relative position information of the respective position to nearby passive reflectors may be measured. Therefore, all positions in the indoor environment may be pre-scanned in the step 141. A position feature set determined or generated for a position in the indoor environment may be referred to as the position feature set of nearby (e.g. K-nearest) passive reflectors with regard to the position in the indoor environment.

As outlined above, the database may be stored in a data storage (e.g. a local memory card) of the device of any one of Figures 1 to 4 or in a remote server.

Figure 15 shows an example of an entry of a database according to an embodiment of the present disclosure for positioning in an indoor environment; wherein the environment comprises passive reflectors of at least two reflector types. The database entry of Figure 15 is an example of an entry of the database according to the fifth aspect of the disclosure. The description of the database of the fifth aspect is correspondingly valid for the database of Figure 15. The database of Figure 15 may be generated by the method of Figure 14.

The database, of which Figure 15 shows an example of an entry, is a database for positioning in an indoor environment, wherein the environment comprises passive reflectors of at least two reflector types. The database comprises a plurality of position feature sets each being associated with a different position in the environment. In other words, the data comprises a plurality of entries, wherein each entry comprises a respective position feature set associated with a different position in the environment. Each position feature set of the database comprises relative position information of the position, associated with the respective position feature set, with regard to K passive reflectors of the passive reflectors of the environment and reflector type information of each of the K passive reflectors. K is an integer number greater or equal to three. In the example of Figure 15, the integer number K equals to four (K = 4). This is only by way of example not limiting the present disclosure. The environment may comprise passive reflectors of two reflector types. This is only by way of example so that more than two reflector types may be present in the indoor environment.

The entry of the database shown in Figure 15 comprises a position feature set (determined or generated e.g. by the method of Figure 14) for a position and the position. That is, the position feature set for the position is associated with the position. The position may be indicated by coordinates. For example, the position may have the coordinates (6.9 m, 10.8 m) in the indoor environment. The position feature set comprises relative position information of the position (6.9 m, 10.8 m) with regard to four (K = 4) passive reflectors of the passive reflectors of the indoor environment. In addition, the position feature set comprises reflector type information of each of the four (K = 4) passive reflectors. As shown in Figure 15, the relative position information may comprise distance information of the position (6.9 m, 10.8 m) with regard to the four (K = 4) passive reflectors. Optionally, the relative position information comprises angle information of the position (6.9 m, 10.8 m) with regard to the four (K = 4) passive reflectors. For example, as shown in Figure 15, the position (6.9 m, 10.8 m) in the indoor environment is a distance of 3. 1 m away from a first passive reflector of a first reflector type “Type 1 ” . The position (6.9 m, 10.8 m) in the indoor environment is a distance of 5.5 m away from a second passive reflector of the first reflector type “Type 1”. Further, the position (6.9 m, 10.8 m) in the indoor environment is a distance of 6.2 m away from a third passive reflector of a second reflector type “Type 2”. Furthermore, the position (6.9 m, 10.8 m) in the indoor environment is a distance of 8.8 m away from a fourth passive reflector of the second reflector type “Type 2”. In addition, the angle information of the position (6.9 m, 10.8 m) with regard to the first passive reflector is equal to (15°, -15°), and the angle information of the position (6.9 m, 10.8 m) with regard to the second passive reflector is equal to (-15°, 30°). The angle information of the position (6.9 m, 10.8 m) with regard to the third passive reflector is equal to (15°, -45°), and the angle information of the position (6.9 m, 10.8 m) with regard to the fourth passive reflector is equal to (75°, -45°).

Thus, when the device of any one of Figures 1 to 4 determines, at a current position, a position feature set that equals or is most similar to the position feature set of the entry of the database shown in Figure 15, the device may be configured to determine that the current position of the device equals to the position (6.9 m, 10.8 m) of the entry of the database shown in Figure 15. For this, the device may compare the determined position feature set (determined at the current position) with the position feature sets of the database and, thus, the position feature set of the entry of Figure 15. For example, the device may search in the database for a position feature set, whose relative position information has the smallest mean square error with respect to the relative position information of the determined position feature set. In case this is true for the position feature set of the entry shown in Figure 15, the current position of the device may be determined to be (6.9 m, 10.8 m), because this position is associated with the position feature set of the entry shown in Figure 15.

In the position feature sets of the database and the determined position feature set, the relative position information may be sorted according to the reflector type information. With regard to the same reflector type information, the relative position information may be sorted according to the distance information. The aforementioned sorting is exemplarily shown in Figure 15 for the position feature set of an entry of the database.

The entry of the database of Figure 15 is an example of the entries of the database that may be used by the device according to any one of Figures 1 to 4 for positioning. The database may comprise for any position in the indoor environment a position feature set of K nearby passive reflectors that are nearest to the respective position. As exemplarily shown in Figure 15, the position feature set may comprise as distance information the sorted distances from the position to each of the K nearby passive reflectors. The position feature set may also comprise the reflector type information for each of the K nearby passive reflectors. Optionally, the position feature set may comprise as angle information relative angles from the position to each of the nearby passive reflectors. Thus, for a position in the environment, features of the position’s K-nearest local reference points (LRPs) in the form of passive reflectors may be viewed as a signature of this position. The features of a position feature set may comprise distance information (e.g. distances) and/or angle information (e.g. relative angles) between the position and the respective local reference point (i.e. the respective passive reflector) as well as reflector type information (e.g. the reflector type) of the respective local reference point. Therefore, when generating an entry of the database of a plurality of position feature sets, the features of K-nearest local reference points to a position of the environment may be grouped together as a position feature set (may be called “LRP fingerprint”) of this position of the environment. Thus, for a specific indoor environment with pre-installed local reference points (in the form of at least three passive reflectors of at least two reflector types), a database may be pre-generated comprising for all positions of the environment a respective position feature set. This allows the device according to any one of Figures 1 to 4 to determine for a current position of the device a position feature set and determine its current position (e.g. the device’s absolute position) by comparing the determined position feature set with the entries and, thus, position feature sets of the pre-generated database. The determined position feature set may be referred to as “run-time detected LRP fingerprint”.

The present disclosure proposes methods for indoor positioning based on passive reference points (in the form of passive reflectors of at least two reflector types) and device active radio sensing. Compared with other methods for indoor positioning (e.g. radio fingerprint based indoor positioning methods) the methods of the disclosure may operate in normal radio frequency and may achieve high-accuracy indoor positioning with low-cost, low-energy and high-robustness against environment dynamics and RF impairments.

The methods for arranging passive reflectors in the indoor environment and generating the database for positioning may correspond to an offline operation. Namely, these method aim to prepare arrangement of passive reflectors of at least two reflector types and a database with a plurality of position feature set for a given indoor environment. They allow the device of any one of Figures 1 to 4 to perform positioning. The methods performable by the device of the present disclosure (e.g. the device of any one of Figures 1 to 4) may correspond to online operation, which run-time or execution allows determining the position (absolute position) of the device within the indoor environment. The present disclosure has been described in conjunction with various embodiments as examples as well as implementations. However, other variations can be understood and effected by those persons skilled in the art and practicing the claimed subject-matter, from the studies of the drawings, this disclosure and the independent claims. In the claims as well as in the description the word “comprising” does not exclude other elements or steps and the indefinite article “a” or “an” does not exclude a plurality. A single element or other unit may fulfill the functions of several entities or items recited in the claims. The mere fact that certain measures are recited in the mutual different dependent claims does not indicate that a combination of these measures cannot be used in an advantageous implementation.

Claims

1. A device (1) for positioning in an indoor environment (5), the environment (5) comprising passive reflectors (4) of at least two reflector types, wherein the device (1) is configured to transmit a radio signal (2) in the environment (5), receive a reflected waveform (3) of the transmitted radio signal, determine, using the received reflected waveform (3), a position feature set, and determine a position of the device (1) in the environment (5) by comparing the determined position feature set with a database comprising a plurality of position feature sets, wherein each of the plurality of position feature sets is associated with a different position in the environment; wherein the determined position feature set comprises relative position information of the position of the device (1) with regard to K passive reflectors, K being an integer number greater than or equal to three, and reflector type information of each of the K passive reflectors.

2. The device (1) according to claim 1, wherein the relative position information of the determined position feature set comprises distance information and/or angle information of the position of the device (1) with regard to the K passive reflectors of the determined position feature set.

3. The device (1) according to claim 2, wherein the device (1) comprises two or more antennas configured to transmit the radio signal (2) and receive the reflected waveform (3) of the transmitted radio signal, and the relative position information of the determined position feature set comprises the angle information of the position of the device (1) with regard to the K passive reflectors of the determined position feature set.

4. The device (1) according to any one of the previous claims, wherein each position feature set of the database comprises the relative position information of the position, associated with the respective position feature set, with regard to K passive reflectors of the passive reflectors (4) of the environment (5), and the reflector type information of each of the K passive reflectors.

5. The device (1) according to claim 4, wherein the relative position information of each position feature set of the database comprises distance information and/or angle information of the position, associated with the respective position feature set, with regard to the K passive reflectors of the respective position feature set.

6. The device (1) according to any one of the previous claims, wherein the device (1) is configured to measure propagation parameters of the received reflected waveform and translate the propagation parameters into relative position information of the position of the device (1) with regard to passive reflectors that contributed to the received reflected waveform.

7. The device (1) according to any one of the previous claims, wherein the device (1) is configured to determine the reflector type information of each of passive reflectors that contributed to the received reflected waveform using one or more precharacterized reflection coefficients of the at least two reflector types, the one or more pre-characterized reflection coefficients comprise a radar-cross-section, RCS, and/or polarimetry features.

8. The device (1) according to any one of the previous claims, wherein the device (1) is configured to compute, for passive reflectors that contributed to the received reflected waveform, the relative position information of the position of the device (1) with regard to the passive reflectors, and the reflector type information of each of the passive reflectors; and select, according to the computed relative position information, among the passive reflectors that contributed to the received reflected waveform the K passive reflectors of the determined position feature set.

9. The device (1) according to any one of the previous claims, wherein the device (1) is configured to transmit a radar signal as the radio signal (2).

10. The device (1) according to any one of the previous claims, wherein the device (1) is configured to transmit, as the radio signal (2), a cellular communication signal to a base station.

11. The device (1) according to any one of the previous claims, wherein the integer number K is equal to at least three or at least four. The device (1) according to any of the previous claims, wherein the device (1) comprise a data storage and is configured to store the database in the data storage. The device (1) according to any one of the previous claims, wherein the device (1) is configured to compare the determined position feature set with the database by transmitting a query message comprising the determined position feature set to a remote server comprising the database, and the device (1) is configured to determine the position of the device in the environment (5) by receiving a message comprising the position of the device (1) in response to transmitting the query message. The device (1) according to any one of the previous claims, wherein the device (1) is configured to move from a first position to a second position in the environment (5), transmit at the second position a radio signal (2) carrying a query message comprising the determined position feature set that is determined with regard to the first position of the device (1), receive a reflected waveform (3) of the transmitted radio signal carrying the query message, and determine, using the received reflected waveform, a position feature set for the second position. The device (1) according to any one of the previous claims, wherein the device (1) comprises one or more antenna lenses (7) configured to direct the radio signal transmitted by the device in a direction of the passive reflectors (4) of the indoor environment (5). The device (1) according to any one of the previous claims, wherein the database is associated with an ID, and the device (1) is configured to use the database only in case the ID is valid for the indoor environment (5). The device (1) according to any one of the previous claims, wherein the device (1) is a robot, a helmet or a mobile phone. The device (1) according to any one of the previous claims, wherein the device is configured to determine the position feature set by computing, based on the received reflected waveform, a channel impulse response, CIR, and determining, in the computed CIR, peaks caused by passive reflectors that contributed to the received reflected waveform. The device (1) according to claim 18, wherein the device (1) is configured to determine a delay of each peak of the determined peaks and translate the delay of the respective peak into distance information of the position of the device with regard to the respective passive reflector that caused the respective peak; and/or the device (1) is configured to perform beamforming of each peak of the determined peaks and compute angle information of the position of the device with regard to the respective passive reflector that caused the respective peak. The device (1) according to claim 18 or 19, wherein the device (1) is configured to compute, for each peak of the determined peaks, a radar-cross- section, RCS, of the respective passive reflector that caused the respective peak by computing a transmission power to received power ratio for the respective peak. The device (1) according to any one of claims 18 to 20, wherein the device (1) comprises one or more linear dual-polarized antennas configured to transmit the radio signal and receive the reflected waveform of the transmitted radio signal; and the device (1) is configured to compute, for each peak of the determined peaks, polarimetry features of the respective passive reflector that caused the respective peak by computing a 2x2 scattering matrix for the respective peak. The device (1) according to claim 20 or 21, wherein the device (1) is configured to classify, for each peak of the determined peaks, the reflector type of the respective passive reflector that caused the respective peak using the RCS and/or polarimetry features of the respective passive reflector. A method for determining a position of a device in an indoor environment, the environment comprising passive reflectors of at least two reflector types, wherein the method comprises transmitting (51), by the device, a radio signal in the environment, receiving (52), by the device, a reflected waveform of the transmitted radio signal, determining (53), by the device, a position feature set using the received reflected waveform, and determining (54) the position of the device in the environment by comparing the determined position feature set with a database comprising a plurality of position feature sets, wherein each of the plurality of position feature sets is associated with a different position in the environment; wherein the determined feature set comprises relative position information of the position of the device with regard to K passive reflectors, K being an integer number greater than or equal to three, and reflector type information of each of the K passive reflectors.

24. The method according to claim 23, wherein the step of determining (54) the position of the device in the environment by comparing the determined position feature set with the database comprising a plurality of position feature sets comprises: searching (81), by the device, the database for a position feature set whose relative position information has the smallest mean square error with respect to the relative position information of the determined position feature set, and determining (82) the position associated with the searched position feature set as the position of the device.

25. The method according to claim 23 or 24, wherein the step of determining (54) the position of the device in the environment by comparing the determined position feature set with the database comprising a plurality of position feature sets comprises: transmitting (91), by the device, a query message comprising the determined position feature set to a remote server comprising the database, and receiving (92), by the device, from the remote server a message comprising the position of the device in response to the query message.

26. A system of three or more passive reflectors (4a, 4b) of at least two reflector types, wherein the passive reflectors (4a, 4b) are arranged in an indoor environment such that any three passive reflectors of the three or more passive reflectors do not lie in the same line, a triangle formed by any three passive reflectors of the three or more passive reflectors is not isosceles, and a symmetry line of one pair does not pass through the symmetry point of another pair with regard to any two pairs of the three or more passive reflectors, wherein each pair of the any two pairs comprises maximal one common passive reflector.

27. The system according to claim 26, wherein the three or more passive reflectors are configured to be arranged at a ceiling (6) of the indoor environment. The system according to claim 26 or 27, wherein the at least two reflector types comprise one or more metal reflectors and/or one or more dielectric reflectors. A method for arranging three or more passive reflectors of at least two reflectors types, wherein the method comprises arranging (131) the passive reflectors in an indoor environment such that: any three passive reflectors of the three or more passive reflectors do not lie in the same line, a triangle formed by any three passive reflectors of the three or more passive reflectors is not isosceles, and a symmetry line of one pair does not pass through the symmetry point of another pair with regard to any two pairs of the three or more passive reflectors, wherein each pair of the any two pairs comprises maximal one common passive reflector. A database for positioning in an indoor environment, the environment comprising passive reflectors of at least two reflector types, wherein the database comprises a plurality of position feature sets each being associated with a different position in the environment; and each position feature set of the database comprises relative position information of the position, associated with the respective position feature set, with regard to K passive reflectors of the passive reflectors of the environment, K being an integer number greater or equal to three, and reflector type information of each of the K passive reflectors. A method for generating a database for positioning in an indoor environment, the environment comprising passive reflectors of at least two reflector types, wherein the database comprises a plurality of position feature sets each being associated with a different position in the environment; and each position feature set of the database comprises relative position information of the position, associated with the respective position feature set, with regard to K passive reflectors of the passive reflectors of the environment, K being an integer number greater or equal to three, and reflector type information of each of the K passive reflectors; wherein the method comprises: measuring (141) for a plurality of positions in the indoor environment the relative position information of the respective position to nearby passive reflectors, down-selecting (142), for each of the plurality of positions, the nearby passive reflectors to K passive reflectors, grouping (143), for each of the plurality of positions, the relative position information of the K passive reflectors and the reflector type information of the K passive reflectors as a respective position feature set, and storing (144), for each of the plurality of positions, the respective position feature set in association with the respective position of the plurality of positions in the database.