WO2022117523A2

WO2022117523A2 - Ranging between radio devices

Info

Publication number: WO2022117523A2
Application number: PCT/EP2021/083458
Authority: WO
Inventors: Carsten WULFF
Original assignee: Nordic Semiconductor Asa
Priority date: 2020-12-01
Filing date: 2021-11-30
Publication date: 2022-06-09
Also published as: WO2022117523A3

Abstract

This document discloses a method for determining spatial conditions between a first radio device and a second radio device, the method comprising: path loss ranging, by the first radio device, the second radio device and computing at least one path loss estimate indicating a first distance between the first radio device and the second radio device; phase ranging, by the first radio device, the second radio device and computing at least one phase ranging value indicating a second distance between the first radio device and the second radio device; computing, based on the at least one path loss estimate and the at least one phase ranging value, at least one parameter describing the spatial conditions between the first radio device and the second radio device.

Description

RANGING BETWEEN RADIO DEVICES

TECHNICAL FIELD

Embodiments described herein relate to ranging between two radio devices.

TECHNICAL BACKGROUND

Ranging is conventionally used to determine a distance between two devices. The purpose of the ranging may be to perform link adaptation or to trigger some proximity-based functions, applications, or services. Some conventional methods for performing the ranging use path loss estimation. A path loss estimate is based on one device transmitting a signal with a known transmission power. Another device receiving the signal then measures received signal strength of the signal and, with the knowledge of the transmission power, computes attenuation of the signal in a radio channel between the two devices.

Phase ranging is another method for estimating the distance. In the phase ranging, a first device transmits a first radio signal with a known transmit phase to a second device, and the second device measures the phase at the time it receives the first radio signal. The second device then transmits a second radio signal to the first device, wherein the phase of the second radio signal is the measured phase. Upon receiving the second signal, the first device measures the phase of the received second radio signal, thus deducing a phase difference between the phase of the first radio signal at the transmission and the phase of the second radio signal at the reception. With the knowledge of the phase change (divided by two to represent only one-way phase change), the wavelength of the first radio signal and the second radio signal, and the speed of light, the distance can be computed. A phase ambiguity related to longer distances may be solved by performing the phase ranging on multiple carrier frequencies, as known in the art. Other phase ranging methods are also provided in the art.

BRIEF DESCRIPTION

The invention is defined by the independent claims. Some embodiments are defined in the dependent claims.

According to an aspect, there is provided a method for determining spatial conditions between a first radio device and a second radio device, comprising: path loss ranging, by the first radio device, the second radio device and computing at least one path loss estimate indicating a first distance between the first radio device and the second radio device; phase ranging, by the first radio device, the second radio device and computing at least one phase ranging value indicating a second distance between the first radio device and the second radio device; determining, on the basis of the at least one path loss estimate and the at least one phase ranging value indicating that the first distance is greater than the second distance, that there is an obstacle between the first radio device and second radio device; and outputting at least one parameter indicating presence of the obstacle.

An advantage of the method described above is that the presence of the obstacle can be reliably determined.

In an embodiment, the obstacle is determined to be a wall, if the at least one path loss estimate and the at least one phase ranging value indicate that the first distance is greater than the second distance by at least a determined amount, and wherein the at least one parameter comprises a parameter indicating presence ofthe wall. An advantage of the embodiment is enabling detection of thick obstacles such as walls that potentially degrade or block line-of-sight.

In an embodiment, the at least one parameter describes a physical location of the first radio device and the second radio device, e.g. indoors or outdoors. An advantage of the embodiment acquisition of information on the location by via the distance estimation.

In an embodiment, the at least one path loss estimate comprises a first path loss estimate computed by using a first path loss model associated with first spatial conditions, the method further comprising: computing, a second path loss estimate by using a second path loss model associated with second spatial conditions different from the first spatial conditions; computing a first distance estimate based on the first path loss estimate, a second distance estimate based on the second path loss estimate, and a third distance estimate based on the phase ranging value; correlating the third distance estimate with the first distance estimate and with the second distance estimate and arranging, based on the correlation, the at least one parameter to indicate whether the spatial conditions are the first spatial conditions or the second spatial conditions. An advantage of the embodiment improved path loss estimation via selection of a more suitable path loss model.

In an embodiment, the first path loss model is an indoor model associated with indoor spatial conditions, and wherein the second path loss model is an outdoor model associated with outdoor spatial conditions. An advantage of the embodiment is improved path loss estimation via determination of indoors/outdoors location of the radio devices.

In an embodiment, the method comprises: computing, by using the path loss ranging, a first set of distance estimates indicating the first distance; computing, by using the phase ranging, a second set of distance estimates indicating the second distance; and computing the at least one parameter on the basis of the first set of distance estimates and the second set of distance estimates. An advantage of the embodiment is enabled tracking of the distance.

In an embodiment, the method further comprises computing both the path loss estimate and the phase ranging value by using the same pair of radio signals transferred between the first radio device and the second radio device. An advantage of the embodiment is efficient ranging with low signalling overhead.

According to another aspect, there is provided an apparatus comprising: a processing circuitry configured to: acquire path loss ranging measurement data resulting from path loss ranging between a first radio device and a second radio device and compute at least one path loss estimate indicating a first distance between the first radio device and the second radio device; acquire phase ranging measurement data resulting from phase ranging between the first radio device and the second radio device and compute at least one phase ranging value indicating a second distance between the first radio device and the second radio device; determine, on the basis of the at least one path loss estimate and the at least one phase ranging value indicating that the first distance is greater than the second distance, that there is an obstacle between the first radio device and second radio device; and output at least one parameter indicating presence of the obstacle.

In an embodiment, the processing circuitry is configured to determine that the obstacle is a wall, if the at least one path loss estimate and the at least one phase ranging value indicate that the first distance is greater than the second distance by at least a determined amount, and wherein the at least one parameter comprises a parameter indicating presence of the wall.

In an embodiment, the at least one parameter describes a physical location of the first radio device and the second radio device.

In an embodiment, the processing circuitry is configured to: compute a first path loss estimate by using a first path loss model associated with first spatial conditions, compute a second path loss estimate by using a second path loss model associated with second spatial conditions different from the first spatial conditions; compute a first distance estimate based on the first path loss estimate, a second distance estimate based on the second path loss estimate, and a third distance estimate based on the phase ranging value; correlate the third distance estimate with the first distance estimate and with the second distance estimate and arrange, based on the correlation, the at least one parameter to indicate whether the spatial conditions are the first spatial conditions or the second spatial conditions.

In an embodiment, the first path loss model is an indoor model associated with indoor spatial conditions, and wherein the second path loss model is an outdoor model associated with outdoor spatial conditions.

In an embodiment, the processing circuitry is configured to: compute, by using the path loss ranging, a first set of distance estimates indicating the first distance; compute, by using the phase ranging, a second set of distance estimates indicating the second distance; and compute the at least one parameter on the basis of the first set of distance estimates and the second set of distance estimates.

In an embodiment, the processing circuitry is configured to compute both the path loss estimate and the phase ranging value by using the same pair of radio signals transferred between the first radio device and the second radio device.

According to another aspect, there is provided a computer program product embodied on a (transitory or non-transitory) computer-readable distribution medium and comprising computer program instructions that, when read executed by a processing circuitry, configure the processing circuitry to carry out a computer process comprising: acquiring path loss ranging measurement data resulting from path loss ranging between a first radio device and a second radio device and computing at least one path loss estimate indicating a first distance between the first radio device and the second radio device; acquiring phase ranging measurement data resulting from phase ranging between the first radio device and the second radio device and computing at least one phase ranging value indicating a second distance between the first radio device and the second radio device; determining, on the basis of the at least one path loss estimate and the at least one phase ranging value indicating that the first distance is greater than the second distance, that there is an obstacle between the first radio device and second radio device; and outputting at least one parameter indicating presence of the obstacle.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following the invention will be described in greater detail by means of preferred embodiments with reference to the accompanying drawings, in which

Figure 1 illustrates a system and a scenario to which some embodiments of the invention may be applied;

Figure 2 illustrates a procedure for estimating spatial conditions in which a radio device resides;

Figure 3 illustrates a flow diagram of a process for determining whether or not there is an obstacle between two radio devices according to an embodiment;

Figure 4 illustrates a flow diagram of a process for using phase ranging as a reference for at least one path loss ranging model according to an embodiment;

Figures 5 and 6 illustrate the phase ranging as the reference for the at least path loss ranging model;

Figure 7 illustrates a signalling diagram of a procedure for performing joint phase ranging and path loss ranging according to an embodiment; and

Figure 8 illustrates a block diagram of an apparatus according to an embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

The following embodiments are exemplifying. Although the specification may refer to “an”, “one”, or “some” embodiments] in several locations of the text, this does not necessarily mean that each reference is made to the same embodiment s), ^or that a particular feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments.

Figure 1 illustrates a radio environment and ranging between two radio devices. As described in Background, the ranging may be performed for the purpose of determining a distance between two devices, e.g. radio devices 100 and 102 or 100 and 104. The purpose for the ranging may vary depending on an application using the ranging. The purpose may be to trigger a location-based or a proximity-based function, for example. With the global COVID-19 pandemic, applications using the ranging for the purpose of determining exposure have been developed. There are various application for utilizing the ranging.

As described in Background, there are also several methods for carrying out the ranging. Since the different ranging methods are based on different types of measurements, they are also subject to providing different results under certain (spatial) conditions. For example, the path loss (PL) ranging that is based on measuring signal attenuation in a radio channel is susceptible to not only free space path loss but also additional attenuation caused by obstacles. Accordingly, the path loss ranging may not provide an accurate distance estimate under the spatial conditions where there is an obstacle between the radio devices. On the other hand, the phase (PH) ranging is not as susceptible to the obstacles. This is illustrated in Figure 1 where there is a wall between the radio devices 100 and 104. The path loss ranging may provide a distance estimate that is greater than a distance estimate based on the phase ranging. Accordingly, by using path loss ranging alone the device 104 would appear to be further away than in reality, as illustrated in Figure 1. On the other hand, under other spatial conditions the two ranging estimates may provide distance estimates that are substantially equal. Such spatial conditions may be present when there is a line-of-sight between the radio devices, e.g. the radio devices 100 and 102 in Figure 1.

The two (or more) independent ranging methods thus provide more information on the spatial conditions than use of a single ranging method, e.g. the phase ranging or the path loss ranging. Figure 2 illustrates an embodiment of a process that uses multiple independent (and different) ranging methods for the purpose of determining the spatial conditions. The process may be performed by any one of the devices 100 to 104 of Figure 1. Let us call the device performing the process of Figure 2 a first radio device that performs the ranging with a second radio device. Referring to Figure 2, the process comprises: path loss ranging (block 20) the second radio device and computing at least one path loss estimate indicating a first distance between the first radio device and the second radio device; phase ranging (block 202) the second radio device and computing at least one phase ranging value indicating a second distance between the first radio device and the second radio device; computing (block 204), based on the at least one path loss estimate and the at least one phase ranging value, at least one parameter describing the spatial conditions between the first radio device and the second radio device.

The use of the two independent ranging methods enables determining in what type of spatial conditions the two radio devices are located at, and/or determining spatial conditions between the two radio devices. As a consequence, the use of the multiple independent ranging methods provides new information that is not available by using only one ranging method, and the new information may be used to create new functions and new applications that use this information. The first radio device and the second radio device may be any radio devices comprising a radio transceiver. Figure 1 illustrates a scenario with some examples of such radio devices. Radio devices 100 and 104 represent portable radio devices such as cellular phones, while the radio device 102 represents a wearable radio device (a smart watch). Other types of wearable devices also incorporate a radio modem, e.g. an earpiece or smart glasses. The radio device may support one or more radio communication protocols, e.g. a cellular communication protocol (Long-Term Evolution (LTE) or 5G), Bluetooth protocol, IEEE 802.11 based protocol, or IEEE 802.15 based protocol.

In an embodiment, the phase ranging is the multi-carrier phase ranging described in Background where the phase ranging comprises transmission of a phase ranging signal on multiple carrier frequencies, computing multiple phase ranging values on the basis of the phase ranging signals and using the multiple phase ranging values to determine the second distance.

It can be envisaged that the two ranging methods need not be limited particularly to the combination of the path loss ranging and (multi-carrier) phase ranging. The concept of Figure 2 may be extended to estimation of the distance by using a first ranging method and a second ranging method different from the first ranging method. The first and second ranging methods may use ranging measurement technologies. One of the two ranging methods may be the path loss ranging or phase ranging but the other of the two ranging methods may be a ranging method different from the path loss ranging and different from the phase ranging.

In an embodiment, the at least one parameter describes a physical location of the first radio device and the second radio device. Below, some embodiments are described enabling determination of whether or not the radio devices are indoors or outdoors. In a similar manner, other characteristics of the physical location may be determined in an analogous manner, e.g. a density of obstacles in the physical location.

In an embodiment, the computing in block 204 comprises determining, on the basis of the at least one path loss estimate and the at least one phase ranging value indicating that the first distance is greater than the second distance, that there is an obstacle between the first radio device and second radio device. The difference between the first distance and the second distance depends on the characteristics of the obstacle, e.g. thickness or material. Further, the at least one parameter comprises a parameter indicating presence of the obstacle. Figure 3 illustrates a process according to such an embodiment. Referring to Figure 3, upon determining the first distance with the path loss ranging and the second distance with the phase ranging, the first distance may be compared with the second distance in block 300. If the first distance is substantially greater than the second distance ('yes’ in block 302), the process may proceed to block 304 where it is determined that there is an obstacle between the radio devices. An apparatus performing the process of Figure 3 may thus output the parameter indicating the presence of the obstacle. On the other hand, if the first distance is substantially equal to the second distance (‘no’ in block 302), or even lower than the second distance, the process may proceed to block 306 where it is determined that there is a free space between the radio devices. The apparatus performing the process of Figure 3 may thus output a parameter indicating the free (open) space between the radio devices.

Because the two distances are computed by using different ranging methods and two independent measuring occasions, there may be certain variance in the resulting distance metrics. Therefore, the comparison in block 302 may allow the distance metrics to have a determined amount of difference before the determination of the obstacle is triggered. For example, the first distance may need to be greater than the second distance by at least a determined amount. The determined amount may be discovered and designed for each particular application separately.

In an embodiment of Figure 3, the process is used to determine whether or not there is a line-of-sight between the radio devices. Upon triggering block 304, it may be determined that there is no line-of-sight. Upon triggering block 306, it may be determined that there is the line-of-sight.

The process of Figure 3 may be used to determine a type of the obstacle between the two devices. In an embodiment, the obstacle is determined to be a wall, if the at least one path loss estimate and the at least one phase ranging value indicate that the first distance is greater than the second distance by at least a determined amount. Upon so determining, the at least one parameter comprises a parameter indicating presence of the wall. The determined amount may be substantially larger than the determined amount of triggering the presence of the obstacle in the above-described embodiment. The determined amount used for triggering the detection of the wall may also be designed for a particular application. In an analogous manner, different ranges for the difference between the first and second distance can be mapped to different types of obstacles, e.g. a wall, between the devices. The degree of the difference is an indicator of the thickness and/or density of the obstacle. The actual range values and corresponding classifications of various obstacles can be discovered by experimenting and selected for a particular application.

The ranging by using a combination of multiple ranging methods may be used for various applications. For example, the embodiment of Figure 3 may be used for estimating the exposure mentioned above. If the process of Figure 3 indicates that there is an obstacle between the radio devices, the exposure detection may not be triggered regardless of the proximity between the radio devices. On the other hand, if there is only free space between the radio devices and the distance is determined to below an exposure threshold, the procedure may proceed to monitoring a duration of the exposure by measuring a time the distance without an obstacle therebetween stays below the threshold. If an exposure duration threshold is exceeded, the process may output an indication of the exposure. In another application, the process of Figure 3 is used to determine whether or not users of the radio devices have can see one another. If there is determined to be an obstacle between the radio devices, the 'no line-of-sight’ output may be triggered.

In an embodiment, the multiple ranging methods may be used for detecting motion of obstacles around the radio device carrying out the process of Figure 2. The obstacles may be interpreted as ‘moving’ or ‘people’ under some conditions. For example, the ranging may be performed continuously or for a determined time interval of at least some seconds. If the ranging indicates that the second distance stays substantially constant but the first distance fluctuates by at least a determined amount, the presence of a moving obstacle may be detected. The moving may be understood from the perspective of motion with respect to the radio device(s) performing the ranging, i.e. the obstacle may be moving or the radio device(s) may be moving. The detection may be based on a determined type of fluctuation. For example, if the first distance first increases greatly from a given value and then returns to the given value, it may be determined that an obstacle passed by between the ranging radio devices. Depending on the application using the ranging, the obstacle may be interpreted as a human by default.

In an embodiment related to determining the parameter describing the physical location, the phase ranging is used as a reference for the path loss estimation. As known in the art, the path loss ranging may be based on a path loss model that is designed for a particular location or for particular spatial surroundings. For example, a different path loss model may be applied to outdoor conditions than for indoor conditions. However, when it is unknown in what type of surroundings the radio devices are currently located, the phase ranging may be used as a reference. Figures 4 to 6 illustrate such an embodiment.

Referring to Figure 4, the path loss ranging may comprise acquisition of measurement data for the path loss estimation (block 400). As described above, the measurement data may include at least one transmission (TX) power (PWR) value and at least reception (RX) power value related to transmission and reception of at least one radio signal between the radio devices. The measurement data may then be used in block 402 for estimating the path loss (and the distance) by using a first path loss model (e.g. an outdoor model), thus acquiring a first path loss estimate or a first distance candidate that is based on the first path loss estimate. In block 404, the measurement data is used for estimating the path loss (and the distance) by using a second path loss model (e.g. an indoor model), thus acquiring a second path loss estimate or a second distance candidate that is based on the second path loss estimate. Since the two path loss estimates are computed by using different path loss models, they are linked to different spatial conditions defined by the different path loss models. Instead of the indoor and outdoor models, other models may be used. For example, a path loss model for home or office environments may be used, or a path loss model for industrial environments. One representation of the path loss follows the following Equation:

Path Loss = 10 * n * logW(Distance) — 20 * log[c/(4 f)] where n is defined by the selected path loss model, c represents the speed of light, and f a frequency of the transmitted radio signal. By measuring the path loss, the distance may be solved.

Upon computing blocks 402 and 404 and deriving path loss distance estimates by using the two or more different path loss models, the phase ranging distance estimate(s) computed in block 202 by using the phase ranging may be used as a reference for determining which one of the path loss models matches with the current environment of the radio devices. In block 406, each of the path loss distance estimates is correlated with the phase ranging distance estimate(s), thus providing at least one correlation value per path loss model. In block 408, it is determined which one of the correlation values represents the highest correlation with the phase ranging distance estimate. Upon determining the correlation value providing the highest correlation with the phase ranging distance estimate, the process may output a parameter indicating the spatial conditions associated with the path loss model that provided the highest correlation with the phase ranging distance estimate. Figures 5 and 6 illustrate some examples of the distance estimates. As illustrated in Figures 5 and 6, the process of Figure 2 or 4 may include performing multiple ranging measurements with each ranging method for a determined time interval. The measurements with the ranging methods may be performed concurrently to get comparable ranging measurement data for the correlation. The time interval may be in the order of several seconds or even several minutes.

In Figures 5 and 6, the solid line represents the path loss distance estimates based on the outdoor or open space path loss model. The dashed line represents the path loss distance estimates based on the indoor path loss model, and the dotted line represents the phase ranging distance estimates. Figure 5 illustrates a scenario where the indoor path loss model provides a closer match with the phase ranging distance estimation, and the procedure of Figure 4 will conclude that the radio devices are indoors. Figure 6 illustrates a scenario where the open space (outdoor) path loss model provides a closer match with the phase ranging distance estimation, and the procedure of Figure 4 will conclude that the radio devices are in an open space, e.g. outdoors.

As described above, the multiple distance estimates may be measured and estimated. This improves the accuracy of the estimation because isolated errors in the measurements or analysis will be filtered out. Accordingly, in an embodiment a first set of distance estimates indicating the first distance are computed on the basis of the phase ranging measurements. Further, a second set of distance estimates indicating the second distance are computed on the basis of the phase ranging measurements. The at least one parameter is then computed on the basis of the first set of distance estimates and the second set of distance estimates.

In an embodiment, the path loss estimate and the phase ranging value are computed by using the same pair of radio signals transferred between the radio devices. In other words, the same signalling may be used for both measurements. This improves efficiency of the ranging and reduces a number of signals in the radio interface. Figure 7 illustrates a signalling diagram according to this embodiment.

Referring to Figure 7, the radio device 100 may generate a phase ranging signal and transmit the phase ranging signal in step 702. The radio device 102 receives the phase ranging signal in step 702 and measures the phase of the phase ranging signal (block 704) at the time of receiving the phase ranging signal. Then, the radio device 102 may generate another phase ranging signal. The radio device may also arrange the phase ranging signal to have a default or determined transmission power that is known to the radio device 100. Then, the radio device 102 transmits the phase ranging signal having the transmission power in step 708. Upon receiving the phase ranging signal in step 708, the radio device 100 measures both the phase and a received signal strength indicator (RSS1) of the received phase ranging signal. The two-way phase ranging in steps 702 and 708 and the phase measurement in step 710 may then be used to compute the phase ranging value representing the above-described second distance. The actual phase ranging method may be any state-of-the-art phase ranging method. With the knowledge of the transmission power and the RSS1, the radio device 100 computes the path loss estimate in block 712, as described above. As a consequence, the two signals used for phase ranging may also be used for the path loss ranging and no additional signals for the path loss ranging are needed.

In an embodiment, the radio devices 100 and 102 may identify themselves in the signals transmitted in steps 702 and 708 so as to enable the radio device 100 determine an identity of the radio device 102 in the ranging. The identification or addressing may be performed by using state-of-the art methods.

The procedure of Figure 7 may be modified to reach the substantially the same result. For example, the radio device 100 may transmit the phase ranging signal in step 702 with the default transmit power known to the radio device 102, and the radio device 102 may measure the RSS1. The radio device 102 may then report the RSS1 or compute and report the path loss estimate (or the estimated distance) to the radio device 100, for example, in connection with the phase ranging signal transmitted in step 708.

Figure 8 illustrates an apparatus comprising a processing circuitry 50, such as at least one processor, and at least one memory 60 including a computer program code (software) 64, wherein the processing circuitry is configured to carry out the process of Figure 2 or any one of its embodiments described above. The apparatus may be for any one of the radio devices 100 to 104. The apparatus may be a circuitry or an electronic device realizing some embodiments of the invention in the radio device, e.g. the apparatus may comprise a circuitry such as a chip, a chipset, a processor, a micro controller, or a combination of such circuitries for the radio device.

The memory 60 may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The memory 60 may comprise a configuration database 66 for storing configuration parameters, e.g. the path loss models.

The apparatus may further comprise a communication circuitry 45 comprising hardware and/or software for providing the apparatus with radio communication capability with other radio devices, as described above. The communication interface 42 may include radio frequency (RF) components such as an antenna, one or more radio frequency filters, a power amplifier, and one or more frequency converters. The communication interface 45 may comprise a radio modem configured to perform baseband and/or RF operations on the transmitted and received signals. The communication interface 42 may comprise hardware and software needed for realizing the radio communications over the radio interface, e.g. according to specifications of one or more communication protocols. The communication interface 45 may further carry out the ranging according to the embodiments described above. The communication interface may carry out the transmission and reception of the radio signals and the measurements on the received radio signals when performing the ranging methods. The communication interface 45 may then output the path loss estimate(s) and the phase ranging values (or directly the distance estimates) to the processing circuitry 50.

The processing circuitry 50 may comprise, as sub -circuitries or submodules, a ranging controller 52, a spatial analyser 54, and an application processor 56. The elements 52 to 56 may realized as physical circuitries or as software modules, or as combination of both. The ranging controller 52 may be configured to control the execution of the ranging methods. For example, upon determining a need to perform the ranging, e.g. upon receiving a command from the application processor 56, the ranging controller may configure the communication circuitry to perform the ranging by using the at least two independent ranging methods. The ranging controller 52 may, in some embodiments, determine a target radio device for the ranging and control the communication circuitry to direct the ranging to the target radio device. The spatial analyser may be configured to perform at least block 204 of Figure 2 or any one of the embodiments that employs the distance estimates acquired via multiple ranging methods. The spatial analyser may output the at least one parameter indicating the spatial conditions between the radio devices. The spatial analyser may output the parameter(s) to the application processor that is configured to execute an application computer program that employs the parameter(s). The application processor may execute one or more functions on the basis of the input parameter(s), compute further parameter(s) on the basis of the input parameter(s), and/or output information related to the input parameter (s) via a user interface of the apparatus (not shown in Figure 8) and/or via the communication circuitry as payload data.

As used in this application, the term ‘circuitry’ refers to one or more of the following: (a) hardware-only circuit implementations such as implementations in only analog and/or digital circuitry; (b) combinations of circuits and software and/or firmware, such as (as applicable): (i) a combination of processor(s) or processor cores; or (ii) portions of processor(s)/software including digital signal processor(s), software, and at least one memory that work together to cause an apparatus to perform specific functions; and (c) circuits, such as a microprocessor(s) or a portion of a microprocessor(s), that require software or firmware for operation, even if the software or firmware is not physically present.

This definition of ‘circuitry’ applies to uses of this term in this application. As a further example, as used in this application, the term “circuitry” would also cover an implementation of merely a processor (or multiple processors) or portion of a processor, e.g. one core of a multi-core processor, and its (or their) accompanying software and/or firmware. The term “circuitry” would also cover, for example and if applicable to the particular element, a baseband integrated circuit, an application-specific integrated circuit (ASIC), and/or a field- programmable grid array (FPGA) circuit for the apparatus according to an embodiment of the invention. The processes or methods described in Figure 2 or any of the embodiments thereof may also be carried out in the form of one or more computer processes defined by one or more computer programs. The computer program(s) may be in source code form, object code form, or in some intermediate form, and it may be stored in some sort of carrier, which may be any entity or device capable of carrying the program. Such carriers include transitory and/or non- transitory computer media, e.g. a record medium, computer memory, read-only memory, electrical carrier signal, telecommunications signal, and software distribution package. Depending on the processing power needed, the computer program may be executed in a single electronic digital processing unit or it may be distributed amongst a number of processing units.

Embodiments described herein are applicable to wireless networks defined above but also to other wireless networks. The protocols used, the specifications of the wireless networks and their network elements develop rapidly. Such development may require extra changes to the described embodiments. Therefore, all words and expressions should be interpreted broadly and they are intended to illustrate, not to restrict, the embodiment. It will be obvious to a person skilled in the art that, as technology advances, the inventive concept can be implemented in various ways. Embodiments are not limited to the examples described above but may vary within the scope of the claims.

Claims

1. A method for determining spatial conditions between a first radio device and a second radio device, comprising: path loss ranging, by the first radio device, the second radio device and computing at least one path loss estimate indicating a first distance between the first radio device and the second radio device; phase ranging, by the first radio device, the second radio device and computing at least one phase ranging value indicating a second distance between the first radio device and the second radio device; determining, on the basis of the at least one path loss estimate and the at least one phase ranging value indicating that the first distance is greater than the second distance, that there is an obstacle between the first radio device and second radio device; and outputting at least one parameter indicating presence of the obstacle.

2. The method of claim 1, wherein the obstacle is determined to be a wall, if the at least one path loss estimate and the at least one phase ranging value indicate that the first distance is greater than the second distance by at least a determined amount, and wherein the at least one parameter comprises a parameter indicating presence of the wall.

3. The method of any preceding claim, wherein the at least one parameter describes a physical location of the first radio device and the second radio device.

4. The method of any preceding claim, wherein the at least one path loss estimate comprises a first path loss estimate computed by using a first path loss model associated with first spatial conditions, the method further comprising: computing, a second path loss estimate by using a second path loss model associated with second spatial conditions different from the first spatial conditions; computing a first distance estimate based on the first path loss estimate, a second distance estimate based on the second path loss estimate, and a third distance estimate based on the phase ranging value; correlating the third distance estimate with the first distance estimate and with the second distance estimate and arranging, based on the correlation, the at least one parameter to indicate whether the spatial conditions are the first spatial conditions or the second spatial conditions.

5. The method of claim 4, wherein the first path loss model is an indoor model associated with indoor spatial conditions, and wherein the second path loss model is an outdoor model associated with outdoor spatial conditions.

6. The method of any preceding claim, comprising: computing, by using the path loss ranging, a first set of distance estimates indicating the first distance; computing, by using the phase ranging, a second set of distance estimates indicating the second distance; and computing the at least one parameter on the basis of the first set of distance estimates and the second set of distance estimates.

7. The method of any preceding claim, further comprising computing both the path loss estimate and the phase ranging value by using the same pair of radio signals transferred between the first radio device and the second radio device.

8. An apparatus comprising: a processing circuitry configured to: acquire path loss ranging measurement data resulting from path loss ranging between a first radio device and a second radio device and compute at least one path loss estimate indicating a first distance between the first radio device and the second radio device; acquire phase ranging measurement data resulting from phase ranging between the first radio device and the second radio device and compute at least one phase ranging value indicating a second distance between the first radio device and the second radio device; determine, on the basis of the at least one path loss estimate and the at least one phase ranging value indicating that the first distance is greater than the second distance, that there is an obstacle between the first radio device and second radio device; and output at least one parameter indicating presence of the obstacle.

9. The apparatus of claim 8, wherein the processing circuitry is configured to determine that the obstacle is a wall, if the at least one path loss estimate and the at least one phase ranging value indicate that the first distance is greater than the second distance by at least a determined amount, and wherein the at least one parameter comprises a parameter indicating presence of the wall.

10. The apparatus of claim 8 or 9, wherein the at least one parameter describes a physical location of the first radio device and the second radio device.

11. The apparatus of any preceding claim 8 to 10, wherein the processing circuitry is configured to: compute a first path loss estimate by using a first path loss model associated with first spatial conditions, compute a second path loss estimate by using a second path loss model associated with second spatial conditions different from the first spatial conditions; compute a first distance estimate based on the first path loss estimate, a second distance estimate based on the second path loss estimate, and a third distance estimate based on the phase ranging value; correlate the third distance estimate with the first distance estimate and with the second distance estimate and arrange, based on the correlation, the at least one parameter to indicate whether the spatial conditions are the first spatial conditions or the second spatial conditions.

12. The apparatus of claim 11, wherein the first path loss model is an indoor model associated with indoor spatial conditions, and wherein the second path loss model is an outdoor model associated with outdoor spatial conditions.

13. The apparatus of any preceding claim 8 to 12, wherein the processing circuitry is configured to: compute, by using the path loss ranging, a first set of distance estimates indicating the first distance; compute, by using the phase ranging, a second set of distance estimates indicating the second distance; and compute the at least one parameter on the basis of the first set of distance estimates and the second set of distance estimates.

14. The apparatus of any preceding claim 8 to 13, wherein the processing circuitry is configured to compute both the path loss estimate and the phase ranging value by using the same pair of radio signals transferred between the first radio device and the second radio device.

15. A computer program product embodied on a computer-readable distribution medium and comprising computer program instructions that, when read executed by a processing circuitry, configure the processing circuitry to carry out a computer process comprising: acquiring path loss ranging measurement data resulting from path loss ranging between a first radio device and a second radio device and computing at least one path loss estimate indicating a first distance between the first radio device and the second radio device; acquiring phase ranging measurement data resulting from phase ranging between the first radio device and the second radio device and computing at least one phase ranging value indicating a second distance between the first radio device and the second radio device; determining, on the basis of the at least one path loss estimate and the at least one phase ranging value indicating that the first distance is greater than the second distance, that there is an obstacle between the first radio device and second radio device; and outputting at least one parameter indicating presence of the obstacle.