EP4208727A1

EP4208727A1 - Large intelligent surface device and system for localization of a wireless communication device

Info

Publication number: EP4208727A1
Application number: EP20820062.6A
Authority: EP
Inventors: Ganghua Yang; Yanchun Li
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2020-11-30
Filing date: 2020-11-30
Publication date: 2023-07-12
Also published as: WO2022111825A1; CN116391403A

Abstract

A large intelligent surface, LIS, device (410) is disclosed. The LIS device comprises one or more reflecting elements (411a-d), wherein each reflecting element is configured to reflect a RF radiation signal received from a wireless transmitter (420) with an adjustable reflectivity. The LIS device further comprises a controller (413) configured to adjust the reflectivity of each reflecting element (411a-d) over time in accordance with a respective reflectivity pattern. Moreover, the LIS device comprises a wireless communication interface (415) configured to transmit reflectivity pattern information, wherein the reflectivity pattern comprises information about the respective reflectivity pattern of each of the one or more reflecting elements. Moreover, a wireless receiver (430) for determining a location of the wireless transmitter (420) based on RF radiation signals reflected by the LIS device (410) is disclosed.

Description

LARGE INTELLIGENT SURFACE DEVICE AND SYSTEM FOR LOCALIZATION OF A WIRELESS COMMUNICATION DEVICE

TECHNICAL FIELD

The present disclosure relates to wireless communications. More specifically, the present disclosure relates to a large intelligent surface (LIS) device and a wireless receiver for localizing a wireless communication device. BACKGROUND

Knowledge of the position of a wireless communication device can be advantageously used, for instance, for improving the communication with the wireless communication device, such as in Multiple-Input Multiple-Output (MIMO) communication scenarios. One known approach for determining the position of a wireless communication device (also known as wireless positioning) relies on resolvable paths and the corresponding anchor points, especially for indoor environments with rich multi-path components.

Figures 1 and 2 show an exemplary reflection scenario from the perspective of a wireless receiver. It is a top view of an L-shaped room. X and Y in figures 1 and 2 denote the X and

Y axis of the 2D coordinate system (in parallel to the floor of the room). The illustrated L- shaped room has 6 walls, wherein the wall on the left is identified as wall "rO" and the other walls in a counterclockwise direction as walls "r1", "r2", "r3", "r4", and "r5", respectively. Since these walls, as reflectors, will reflect incident signals, each of them has an id which begins with letter ‘r’. A line-of-sight (LoS) path 104 corresponds to a wireless transmitter, which defines a physical anchor 101 , while a non-line-of-sight (NLoS) path 105 corresponds to an n-order reflection/diffraction image of the wireless transmitter, which defines a virtual anchor, such as the two exemplary virtual anchors 103 shown in figure 1. The signal transmitted by the wireless transmitter will either reach the wireless receiver directly or be reflected by a wall one or multiple times before reaching the wireless receiver. Such a reflection of a radio wave by a wall or another large surface is like the reflection of light by a mirror. The propagation direction of the radio wave is changed by the reflection and appears for the wireless receiver as a new source at the position of the mirrored source. This new source is referred to as a virtual anchor in the context of localizing a wireless communication device. Figure 1 shows a plurality of virtual anchors, such as the exemplary virtual anchors 103, which, by nature, are located outside of the exemplary L-shaped room shown in figure 1.

Due to a limited system bandwidth or a limited size of the aperture of the antenna array used by the wireless receiver, the angular resolution of the wireless receiver is limited.

This limited angular resolution has the effect that paths, i.e. directions, cannot be resolved, when these paths only have a small spatial or angular separation. For an environment with lots of scattering sources or lots of reflections, such as an indoor environment, multiple unresolved paths can happen frequently. Once two close paths are not resolved, i.e. falsely identified as one, the estimated path delay deviates from the actual delays associated with the unresolved paths.

Figure 2 shows the exemplary L-shaped room of figure 1 with 6 walls, wherein the wall on the left is identified as wall "0" and the other walls in a counterclockwise direction as walls "1", "2", "3", "4", and "5", respectively. A radio wave reflected by wall "0" can be labeled by a vector [0], while a radio wave first reflected by wall "3" and then by wall "5" can be labeled by a vector [3 5] Such multi-reflections cause lots of paths with similar angles and delays. They are referred to as dense multipaths. In an area with such dense multipaths, which are not successfully resolved by a localization system, an estimation of locations can result in large errors (as shown in the dark area in Figure 2, which indicates a very low localization accuracy).

Figure 3 illustrates the power-delay profile (more specifically, in a wireless environment with noise and interference, the per-tap signal-to-interference-plus-noise ratio (SINR)) as a function of the delay of the received signal for the different multipaths identified in figure 2. Generally, a wireless system faces background noise and interference from co-channel systems. For multiple reflection paths generated by multiple reflectors, the power-delay profile of these paths has multiple taps (each path may also be referred to as a tap). Usually, a reference signal with limited transmit power is transmitted for multipath measurement. So, each path has a SINR (referred to as per-tap SINR). A high per-tap SINR value is good for the estimation of a corresponding path delay and/or angle. However, when two paths have similar delays or angles, even these two paths with high per-tap SINR might not be helpful for determining a path delay and/or angle. For instance, the two exemplary paths within the area 305 shown in figure 3 have unresolvable interpath delays. It may also be either difficult for the wireless receiver to associate these paths with their corresponding anchor points, or difficult to estimate the delay angle parameter of each path, due to their mutual interference. Their angle and delay parameters are too close to be individually resolved, which causes unwanted self- interference (different from other sources’ interference). The interference degrades the estimation accuracy of the delay or angle of the multipath components, and, thereby, degrades the localization accuracy.

For addressing the issues of unresolvable paths, super-resolution algorithms or frequency hopping have been suggested for distinguishing between diffused multipaths. Known super-resolution algorithms may improve the ranging/angular resolution by a super- resolution factor, but only to a certain degree. Thus, for some paths with very similar delay, the angles are still unresolvable. Frequency hopping generally requires sequential measurements in multiple frequency bands. Thus, frequency hopping is usually slow and also increases the complexity of the hardware necessary at both the wireless transmitter and the wireless receiver.

SUMMARY

It is an objective of the present disclosure to provide devices for improving the localization of a wireless communication device.

The foregoing and other objectives are achieved by the subject matter of the independent claims. Further implementation forms are apparent from the dependent claims, the description and the figures.

According to a first aspect, a large intelligent surface (LIS) device is provided (also known as digital controllable surface (DCS) device). The LIS device comprises one or more reflecting elements, wherein each reflecting element is configured to reflect a Radio Frequency (RF) radiation signal received from a wireless transmitter with an adjustable reflectivity towards a wireless receiver. In an embodiment, each reflecting element may be further configured to absorb at least a portion of the RF signal. In an embodiment, each reflecting element may be configured to change at least one of the following physical properties of the RF signal: an amplitude, a phase, and a polarization angle of the RF signal. In an embodiment, the one or more reflecting elements of the LIS device may be mounted on the wall or the ceiling of a room. In an embodiment, the wireless transmitter may be, for instance, a wireless base station or a user equipment (UE). In an embodiment, the wireless receiver may be, for instance, a wireless base station or a UE. The RF radiation signal may be any type of RF radiation signal emitted, for instance, by a base station or a UE. In an embodiment, a wireless transceiver, such as a base station or a user equipment, may comprise the wireless transmitter and the wireless receiver. In other words, in an embodiment, the wireless transceiver may generate the RF radiation signal(s) and receive the resulting RF signal(s) reflected, for instance, by the LIS device.

The LIS device according to the first aspect further comprises a controller configured to adjust the respective adjustable reflectivity of each of the one or more reflecting elements over time in accordance with a respective reflectivity pattern. Moreover, the LIS device comprises a wireless communication interface configured to transmit, e.g. unicast, multicast or broadcast, reflectivity pattern information to the wireless receiver, wherein the reflectivity pattern information comprises information about the respective reflectivity pattern of each of the one or more reflecting elements. The communication interface may further allow the LIS device to be synchronized with other wireless communication devices, e.g. a wireless transmitter or a wireless receiver, or another LIS device. Advantageously, the LIS device assists the wireless receiver in determining the location of the wireless transmitter or the wireless transceiver in determining its own position in that the wireless receiver may, based on the information about the respective reflectivity pattern of each of the one or more reflecting elements, determine those RF signals received from the wireless transmitter that have been reflected by the one or more reflecting elements of the LIS device and, thereby, determine the location of the wireless transmitter more accurately.

In a further possible implementation form, the one or more reflecting elements are arranged in a plane as a coplanar array of reflecting elements.

In a further possible implementation form, a first subset of the one or more reflecting elements is arranged in a first plane as a first array and a second subset of the one or more reflecting elements is arranged in a second plane as a second array at an angle, in particular a right angle, with respect to the first plane. Such a LIS device may be installed, for instance, in a corner of a room.

In a further possible implementation form, for each reflecting element of the one or more reflecting elements, the reflectivity pattern has a continuous or discrete dependence of the reflectivity of the reflecting element overtime. In a further possible implementation form, for each reflecting element of the one or more reflecting elements, the reflectivity pattern comprises a first state having a first reflectivity of the reflecting element and a second state having a second reflectivity of the reflecting element (different to the first reflectivity).

In a further possible implementation form, the reflectivity patterns of at least two of the one or more reflecting elements are orthogonal in time.

In a further possible implementation form, the one or more reflectivity patterns of the one or more reflecting elements are configured to minimize at least one of a transition from the first state to the second state and a transition from the second state to the first state.

In a further possible implementation form, the reflectivity pattern information further comprises information defining one or more freeze periods, wherein, during the one or more freeze periods, the reflectivity of each reflecting element of the one or more reflecting elements is constant, i.e. does not change overtime.

In a further possible implementation form, the reflectivity pattern information further comprises information about at least one of a location and an orientation of the LIS device, in particular at least one of the location and the orientation of the one or more reflecting elements.

In a further possible implementation form, the reflectivity pattern information further comprises a unique identifier of the LIS device.

According to a second aspect, a wireless RF receiver for determining a location of, i.e. localizing, a wireless transmitter is provided. In an embodiment, the wireless transmitter may be, for instance, a wireless base station or a user equipment (UE). In an embodiment, the wireless receiver may be, for instance, a wireless base station or a UE.

In an embodiment, the wireless transmitter and the wireless receiver may be components of a single wireless transceiver, such as a wireless base station or a user equipment.

Thus, in an embodiment, the wireless transceiver may generate the RF radiation signal(s) and receive the resulting RF signal(s) reflected, for instance, by the LIS device for determining its own location. The wireless receiver according to the second aspect comprises a wireless communication interface configured to receive a plurality of single or multiple (i.e. one or more times) reflected RF radiation signals from the wireless transmitter. The wireless communication interface is further configured to obtain, e.g. receive, reflectivity pattern information from a LIS device, wherein the reflectivity pattern information comprises information about a respective reflectivity pattern of each of one or more reflecting elements of the LIS device. In an embodiment, the one or more reflecting elements of the LIS device may be mounted on the wall or the ceiling of a room.

The wireless receiver further comprises a processing circuitry configured to determine, based on the reflectivity pattern information and the plurality of single or multiple reflected RF radiation signals from the wireless transmitter, the location of the wireless transmitter. Thus, advantageously, the wireless receiver (or wireless transceiver) may, based on the information about the respective reflectivity pattern of each of the one or more reflecting elements, determine those RF signals received from the wireless transmitter (or wireless transceiver) that have been reflected by the one or more reflecting elements of the LIS device and, thereby, determine the location of the wireless transmitter (or wireless transceiver) more accurately.

In a further possible implementation form, the processing circuitry of the wireless receiver is configured to determine the location of the wireless transmitter by determining, based on the reflectivity pattern information, at least one of the plurality of single or multiple reflected RF radiation signals from the wireless transmitter that has been reflected by the one or more reflecting elements of the LIS device.

According to a third aspect, a system for determining a location, i.e. position, of a wireless transmitter is provided. The localization system comprises a LIS device according to the first aspect and a wireless receiver according to the second aspect.

According to a fourth aspect, a method for operating a large intelligent surface (LIS) device is provided, wherein the LIS device comprises one or more reflecting elements, wherein each of the one or more reflecting elements is configured to reflect a RF radiation signal received from a wireless transmitter with an adjustable reflectivity towards a wireless receiver. In an embodiment, the wireless transmitter may be, for instance, a wireless base station or a user equipment (UE). In an embodiment, the wireless receiver may be, for instance, a wireless base station or a UE. In an embodiment, a wireless transceiver, such as a base station or a user equipment, may comprise the wireless transmitter and the wireless receiver. In other words, in an embodiment, the wireless transceiver may generate the RF radiation signal(s) and receive the resulting RF signal(s) reflected, for instance, by the LIS device.

The method according to the fourth aspect comprises the steps of: adjusting the respective adjustable reflectivity of each of the one or more reflecting elements over time in accordance with a respective reflectivity pattern; and transmitting reflectivity pattern information, wherein the reflectivity pattern information comprises information about the respective reflectivity pattern of each of the one or more reflecting elements.

According to a fifth aspect, a method for determining a location of, i.e. localizing, a wireless transmitter is provided. In an embodiment, the wireless transmitter may be, for instance, a wireless base station or a user equipment (UE). In an embodiment, the wireless receiver may be, for instance, a wireless base station or a UE. In an embodiment, a wireless transceiver, such as a base station or a user equipment, may comprise the wireless transmitter and the wireless receiver. In other words, in an embodiment, the wireless transceiver may generate the RF radiation signal(s) and receive the resulting RF signal(s) reflected, for instance, by the LIS device.

The localization method according to the fifth aspect comprises the steps of: receiving a plurality of single or multiple (i.e. one or more times) reflected RF radiation signals from the wireless transmitter; obtaining, e.g. receive, reflectivity pattern information from a LIS device, wherein the reflectivity pattern information comprises information about a respective reflectivity pattern of each of one or more reflecting elements of the LIS device; and determining, based on the reflectivity pattern information and the plurality of single or multiple reflected RF radiation signals from the wireless transmitter, the location of the wireless transmitter.

The methods according to the fourth and fifth aspect of the present disclosure can be performed by the LIS device according to the first aspect of the present disclosure and/or the wireless receiver according to the second aspect. Thus, further features of the methods according to the fourth and fifth aspect of the present disclosure result directly from the functionality of the LIS device according to the first aspect and/or the wireless receiver according to the second aspect of the present disclosure as well as their different implementation forms described above and below. According to a sixth aspect, a computer program product comprising a non-transitory computer-readable storage medium for storing program code which causes a computer or a processor to perform the method according to the fourth aspect, when the program code is executed by the computer or the processor, is provided.

Details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description, drawings, and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, embodiments of the present disclosure are described in more detail with reference to the attached figures and drawings, in which:

Fig. 1 shows an exemplary scenario for the localization of a wireless communication device within an L-shaped room;

Fig. 2 illustrates for the scenario of figure 1 the degrading effect of diffused multipaths on the localization accuracy;

Fig. 3 illustrates an example of an unresolvable path delay for the scenario of figures 1 and 2;

Fig. 4a is a schematic diagram illustrating a system for determining the location of a wireless communication device, including a LIS device according to an embodiment;

Fig. 4b is a schematic diagram illustrating stages for determining the location of a wireless communication device in the system shown in figure 4a;

Fig. 4c is a schematic diagram illustrating a system for determining the location of a wireless communication device, including a LIS device according to an embodiment;

Fig. 4d is a schematic diagram illustrating stages for determining the location of a wireless communication device in the system shown in figure 4c; Fig. 5 is a schematic diagram illustrating the reflection behaviour of a LIS device according to an embodiment at two different time instances;

Fig. 6 is a schematic diagram illustrating reflectivity pattern information distributed by a LIS device according to an embodiment;

Fig. 7 is a flow diagram illustrating processing steps implemented by the system of figure 4;

Fig. 8 is a schematic diagram illustrating reflectivity pattern information distributed by a LIS device according to an embodiment;

Fig. 9 is a schematic diagram illustrating data emitted by a wireless transceiver according to an embodiment;

Fig. 10 is a flow diagram illustrating a method of operating a LIS device according to an embodiment; and

Fig. 11 is a flow diagram illustrating a localization method according to an embodiment.

In the following, identical reference signs refer to identical or at least functionally equivalent features.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the following description, reference is made to the accompanying figures, which form part of the disclosure, and which show, by way of illustration, specific aspects of embodiments of the present disclosure or specific aspects in which embodiments of the present disclosure may be used. It is understood that embodiments of the present disclosure may be used in other aspects and comprise structural or logical changes not depicted in the figures. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims.

For instance, it is to be understood that a disclosure in connection with a described method may also hold true for a corresponding device or system configured to perform the method and vice versa. For example, if one or a plurality of specific method steps are described, a corresponding device may include one or a plurality of units, e.g. functional units, to perform the described one or plurality of method steps (e.g. one unit performing the one or plurality of steps, or a plurality of units each performing one or more of the plurality of steps), even if such one or more units are not explicitly described or illustrated in the figures. On the other hand, for example, if a specific apparatus is described based on one or a plurality of units, e.g. functional units, a corresponding method may include one step to perform the functionality of the one or plurality of units (e.g. one step performing the functionality of the one or plurality of units, or a plurality of steps each performing the functionality of one or more of the plurality of units), even if such one or plurality of steps are not explicitly described or illustrated in the figures. Further, it is understood that the features of the various exemplary embodiments and/or aspects described herein may be combined with each other, unless specifically noted otherwise.

Figure 4a shows a localization system 400 for determining the position of a wireless communication device 420 emitting RF signals, i.e. a wireless transmitter 420. As illustrated in figure 4a, the wireless transmitter 420 may be a user equipment, UE, 420. In another embodiment, the wireless transmitter 420 may be a base station (as illustrated by the embodiment shown in figure 4c) or a different type of electronic device emitting RF signals, such as a tablet computer.

As can be taken from figure 4a, the localization system 400 further comprises a wireless receiver 430 for determining the location of the wireless transmitter 420 as well as a large intelligent surface, LIS, device 410 for assisting the wireless receiver 430 in determining the location of the wireless transmitter 420. In an embodiment, the wireless receiver 430 may be, for instance, a base station, i.e. wireless access point (as illustrated in figure 4) or a user equipment, UE (as illustrated by the embodiment shown in figure 4c). In an embodiment, the localization system 400 may comprise more than one LIS device 410 (as illustrated in the examples shown in figures 4b and 4d). In figure 4a, the wireless transmitter, such as a UE, 420 emitting the RF signals and the wireless receiver, such as a base station, 430 are illustrated as separate elements. In further embodiments, the wireless transmitter 420 and the wireless receiver 430 may be the components of a single wireless transceiver.

The LIS device 410 comprises one or more RF reflecting elements 411a-d. In the embodiment shown in figures 4a and 4c, the LIS device 410 comprises, by way of example, four RF reflecting elements 411a-d. As illustrated in figures 4a and 4c, in an embodiment, each reflecting element 411a-d may have a square or rectangular shape. Each reflecting element 411a-d of the LIS device 410 is configured to reflect a RF radiation signal received from the wireless transmitter 420 with an adjustable reflectivity.

In an embodiment, the reflecting elements 411a-d are arranged in a plane as an array, such as the 2x2 array of reflecting elements 411a-d illustrated in figures 4a and 4c. In an embodiment, the RF reflecting elements 411a-d of the LIS device 410 may be mounted on a wall or a ceiling of a room. In a further embodiment, the reflecting elements 411 a-d of the LIS device 410 may be arranged and configured to be arranged in a corner of a room. For instance, in an embodiment, a first subset of the reflecting elements 411 a-d may be arranged in a first plane as a first array and a second subset of the reflecting elements 411 a-d may be arranged in a second plane as a second array at an angle, in particular a right angle with respect to the first plane.

The LIS device 410 further comprises a controller 413 configured to adjust the respective adjustable reflectivity of each of the reflecting elements 411 a-d over time in accordance with a respective reflectivity pattern. Moreover, the LIS device 410 comprises a wireless communication interface 415 configured to transmit reflectivity pattern information 600 (as will be described in more detail in the context of figures 6 and 8) to the wireless receiver 430, wherein the reflectivity pattern information 600 comprises information 603 about the respective reflectivity pattern of each of the reflecting elements 411 a-d of the LIS device 410.

In the embodiment shown in figures 4a and 4c, the wireless receiver 430 further comprises a processing circuitry 431 configured to determine based on the reflectivity pattern information 600 and the plurality of single or multiple reflected RF radiation signals from the wireless transmitter 420 the location of the wireless transmitter 420. For instance, in an embodiment, the processing circuitry 431 of the wireless receiver 430 is configured to determine, based on the reflectivity pattern information 600, at least one of the plurality of single or multiple reflected RF radiation signals from the wireless transmitter 420 that has been reflected by the reflecting elements 411 a-d of the LIS device 410 for distinguishing these signals from signals not reflected by the reflecting elements 411 a-d of the LIS device 410 and thereby more accurately determine the location of the wireless transmitter 420 (e.g. distinguish between several LIS devices 410, and/or distinguish between a LIS device 410 and reflections by non-LIS devices). As illustrated in figures 4a and 4c, the wireless receiver 430 may further comprise a memory 435 configured to store, for instance, the reflectivity pattern information 600 received from the LIS device 410. Figure 4b illustrates for the system of figure 4a a scenario, where the fixed base station 430 is to locate the position of the UE 420 based on a RF transmit signal of the UE 420 using two LIS devices 410.

Figure 4d illustrates for the system of figure 4c a scenario, where the UE as the wireless receiver 430 is to locate its own position based on a RF transmit signal of the base station 420. i.e. the wireless transmitter using two LIS devices 410.

As will be appreciated, the phase and amplitude of the path reflected by the LIS device 410 will change with the reflective properties of the reflecting elements 411 a-d of the LIS device 410. The phase and amplitude of the paths reflected by objects other than the LIS device 410 are generally fixed, in case of a static wireless transmitter 420 and receiver 430 pair. For a movement of the wireless transmitter 420, the reflecting object and/or the wireless receiver 430, the phase and amplitude of the paths reflected by a reflecting object other than the LIS device 410 change very slowly over time, due to the changing distances between the wireless transmitter 420, the reflecting object and/or the wireless receiver 430.

However, the adjustment of the respective adjustable reflectivity of each of the reflecting elements 411 a-d by the controller 413 of the LIS device 410 over time in accordance with a respective reflectivity pattern allows differentiating between signals reflected by the LIS device 410 and signals reflected by objects other than the LIS device 410. In an indoor scenario with pedestrian speed, the channel coherent time is about 0.05 seconds, which is much larger than the response time of the controller 413 of the LIS device 410 (< 1 u s) , which, in an embodiment, may comprise a phase shifter for adjusting the reflectivity of each of the reflecting elements 411 a-d. This implies that the reflectivity of the reflecting elements 411 a-d of the LIS device 410 may vary rapidly so that the LIS device 410 is easily detectable within a given environment, such as an indoor environment.

In an embodiment, the system 400 shown in figures 4a and 4c may be configured to implement the following scheme for localizing the wireless transmitter 420.

1. The controller 413 of the LIS device 410 adjusts the respective state (e.g. reflectiveness, transparency property) of the reflecting elements 411 a-d as a function of time, as defined by the respective reflectivity pattern. 2. The reflectivity pattern information 600 is distributed by the LIS device 410. In an embodiment, the LIS device 410 may transmit the reflectivity pattern information 600 to a wireless access point or base station for broadcasting the reflectivity pattern information 600.

3. In an embodiment, the reflectivity pattern information 600 may comprise information 605, 607 about a location or orientation of the LIS device 410, for instance, a geo-location information, such as a 2d or 3d coordinate, about, for instance, the location of the LIS device 410, the reflecting elements 411a-d and/or the location of a virtual image of the wireless receiver 430 (virtual transmitter).

4. The wireless receiver 430 can determine the path from the LIS device 410 and estimate its location based on the estimated (multi)path information (such as delay or range or angle).

5. In an embodiment, the reflectivity pattern information 600 may further comprise information 602 about the type of the LIS device 410. For instance, the information 602 about the type of the LIS device 410 may specify the reflecting elements 411a-d to be arranged in a planar array or in a cornered arrangement, which may result in a further scattering/reflection.

6. In an embodiment, the reflectivity pattern information 600 provided by the LIS device 410 further comprises information defining one or more freeze periods, wherein during the one or more freezes periods the reflectivity of each reflecting element of the one or more reflecting elements 411a-d is constant, i.e. will not change its status to enable a stable channel for communication.

Figure 5 is a schematic diagram illustrating a mathematical representation describing the reflection behaviour of the LIS device 410 and the one or more reflecting elements 411a-d according to an embodiment at two different time instances. As can be taken from figure 5, the propagation channel coefficient matrix at time t can be represented by With denotes the set of channel path components contributed by the reflecting elements 411a-d of the LIS device 410. denotes the set of channel path components contributed by LoS or any NLoS from obstacles other than the reflecting elements 411a-d of the LIS device 410. θ_k, and Φ_k are the Angle of Arrival (AoA) and Angle of Departure (AoD) for the channel path are the steering vectors for Φ_i respectively. α_i is the channel propagation factor contributed by the path loss (i.e. the reduction of the RF due to propagation along the channel), and reflection (if NLoS). α_l is the channel propagation factor contributed by the path loss. is the reflection coefficient of the l-th reflecting element 411a-d at time t.

For illustration purposes, the example shown in figure 5 involves only 2 paths in total, where a first path is reflected by the LIS device 410 and a second path does not interact with the LIS device 410. At time t₀, the reflection coefficient ) is high and at time t₁, β_l (t1) is low. In other words, in this embodiment, the reflectivity of one or more of the reflecting elements 411a-d of the LIS device 410 may flip-flop between these two states. When the wireless receiver 420 is to be localized, it may be notified that there is the LIS device 410 deployed in the environment. With this information the wireless receiver 420 may measure a channel response multiple times (>=2) so that the paths in and can be differentiated. For instance, for two measurements of the channel responses, H( 1) and H( 2) can be obtained with and As will be appreciated, the above example for two measurements of the channel response can be easily extended to more general scenarios, where are described by similar equations. In an embodiment, one or more of the reflecting elements 411a-d of the LIS device 410 may be controlled by the controller 413 to have binary discrete reflection states. For instance, the Z-th reflective element 411a-d may have the binary discrete states describing its reflectivity properties with:

In an embodiment, the controller 413 of the LIS device 410 may be configured to use different code sequences, i.e. reflectivity patterns, for different reflecting elements 411a-d. In an embodiment, the code sequences used for multiple reflecting elements 411a-d may be orthogonal to each other, i.e.

Figure 6 is a schematic diagram illustrating exemplary reflectivity pattern information 600 distributed by the LIS device 410 according to an embodiment. As illustrated in figure 6 and already described above, the reflectivity pattern information 600 may comprise, in addition to the information 603 about the respective reflectivity pattern, i.e. the code pattern of each of the one or more reflecting elements 411a-d, an identifier 601 of the LIS device 410, virtual anchor coordinates 605, as well as information 607 about the virtual anchor orientation. When each reflecting element 411a-d or the LIS device 410 as a whole has 2 (or more) discrete states, i.e. denotes a one-hot vector (with length of is the number of states, or equivalently, the length of state vector which may be used for activating one of the binary/multi-states for the element i-th reflecting element 411a-d of the LIS device 410 at a time t. The vector of reflection coefficients for all LIS elements is given as

Figure 7 is a flow diagram illustrating processing steps implemented by the system 400 of figure 4c for the scenario, where the UE as the wireless receiver 430 is to locate its own position based on a RF transmit signal of the base station 420. i.e. the wireless transmitter using the LIS device 410. In a fist stage 701 , the LIS device 410 or another party provides the reflectivity pattern information 600, e.g. a message 600 including the data fields (LIS code c_l(t), location p_l mode (1/2)), contains LIS code c_l(t) location p_l optionally include mode (1 : reflection/2: corner reflection)). The wireless transmitter 420 and/or the wireless receiver 430 (or in a further embodiment the wireless transceiver comprising the wireless transmitter 420 and the wireless receiver 430) can receive and obtain this info. The controller 413 of the LIS device 410 changes the reflectivity of the reflecting elements 411a-d with time according to the reflectivity pattern, e.g. the LIS code .

In a second stage 703, the wireless receiver 430 may measure the channel response (channel impulse response or channel frequency response, or any other form of channel response, e.g. in a transform domain) over time. Thus, in an embodiment, the wireless receiver 430 may obtain a sequence of channel responses, e.g. H(t), t = 1,2, ....

In a third stage 705, the wireless receiver 430 may obtain , for each reflecting elements with dedicated LIS code c_l(t). The example is a possible simple way with linear processing for H(t) with two snapshots in time. By using an estimator (e.g. zero-forcing) with the knowledge of c_l(t), per LIS-path steering matrix may be obtained. Further, by using an angle estimator (e.g. 2D MUSIC), the wireless receiver 420 may estimate θ_l and

In a fourth stage 707, by using the estimator (e.g. zero-forcing) with the knowledge of c_l (t), a natural channel coefficient matrix H_j(t) can be obtained by wireless receiver 420. Natural paths' parameter θ and Φ_i may be estimated by a multipath estimator, such as MUSIC, SAGE, and the like.

In a fifth stage 709, the wireless receiver 430 uses location to estimate the final location of the device 430, i.e. its own location.

As will be appreciated, if the location of the wireless receiver 430 is known, but the location of the LIS device 410 is unknown (e.g. after LIS device's 410 initial installation or later replacement), the wireless receiver 430 may use its own location and to estimate the final location of the LIS device 410. It may be used for an automatic location labeling by the LIS device 410. In an embodiment, the wireless receiver 430 may also send a quantized or compressed version of the sequence of H(t), to another device to execute stages 3, 4, and 5 above. If the wireless receiver 430 can also send a quantized or compressed version of the sequence of H (t), to the wireless transmitter 420, then wireless transmitter 420 may obtain the LIS code c_l(t), and the location p_l for location estimation in stages 3, 4, and 5 described above.

In an embodiment, the one or more reflectivity patterns used by the controller 413 for the one or more reflecting elements 411 a-d of the LIS device 410 are configured to minimize transitions from a first reflectivity state to a second reflectivity state and back from the second reflectivity state to the first reflectivity state. In other words, in an embodiment, the code sequence(s) may be designed to minimize the total number of state transitions and, thereby, power consumption. For example, the state at time t for all reflecting elements 411 a-d in the set may be and the code sequence(s) may be determined based on the following equation:

In an embodiment, the respective reflectivity patterns used by the controller 413 of the LIS device 410 may be digital/discrete binary sequences (on-off like), or multiary sequences. Alternatively, the respective reflectivity patterns used by the controller 413 of the LIS device 410 may be analog, i.e. continuous functions. For instance, in an embodiment, the one or more reflecting elements 411 a-f of the LIS device 410 may be mounted on a shaft of a motor rotating with a constant or varying speed.

As already described above, in an embodiment, the system 400 may comprise more than one LIS device 410. In an embodiment with multiple LIS devices 410, some of these LIS devices may be of the LIS device type with a planar arrangement of the reflecting elements, while some other ones may be of the LIS device type with a cornered arrangement of the reflecting elements. These LIS devices may be operated in two modes, namely a controllable specular reflection mode (mode 1) or a controllable corner reflection mode (mode 2). When the wireless transmitter, e.g. the UE 430 supports a full duplex mode, it can receive its transmitted signal. The transmitted signal may be a FMCW or other signal, which enables canceling self-interference, and keeping the reflected echo of the transmitted signal. When being used as a corner reflector (mode 2), the LIS device 410 may act as an anchor in addition to the location of the wireless receiver 420. The location of the LIS device 410 itself may be used as an anchor location. The LIS device location and mode info (mode 2) may be included in a prior information message.

Figure 8 is a schematic diagram illustrating exemplary reflectivity pattern information 600 distributed by the LIS device 410 according to a further embodiment. As illustrated in figure 8, the reflectivity pattern information 600 may comprise, in addition to the information 603 about the respective reflectivity pattern of each of the one or more reflecting elements 411 a-d, an identifier 601 of the LIS device 410, a type identifier 602, virtual anchor coordinates 605, as well as information 607 about the virtual anchor orientation.

As will be appreciated, in an embodiment where the system 400 comprise different types of LIS devices 401 , i.e. mode 1 and mode 2 LIS devices 401 , the plane reflectors may help the device 410 that does not have FD/FMCW capability, while the corner reflectors may assist the plane reflectors at the area where the signal of the wireless transmitter 420 could arrive at plane with too low power level.

Since, during the communication stage, the channel is preferred to be static to minimize channel estimation and tracking overhead, the reflectivity pattern indicator may also indicate a cycle for freeze states for the coexistence between localization and communication, wherein during a freeze state or period the reflecting elements 411 a-d of the LIS device 410 do no state change their reflectivity.

In a further embodiment, as illustrated in figure 9, the communication interface 415 of the LIS device 410 may implement a receive module, when it receives an indication for packet start. In an embodiment, the packet start can be a preamble signal with sequence defined according to a telecommunication standard.

Figure 9 illustrates one of the problems addressed by embodiments disclosed herein, namely that the varying reflectivity of the reflecting elements 411 a-d of the LIS device 410 may change or degrade the wireless communication performance. During a time period k- 1 , a preamble is transmitted. The receiver 430 estimates the channel response based on the received preamble signal. This channel response is measured when the reflecting elements 411 a-d of the LIS device 410 are in a state described by When the reflectivity state of the reflecting elements 411 a-d of the LIS device 410 changes according to the reflectivity pattern to the state in time period k, the channel response will change, i.e. will be different from the previously measured channel response. However, the wireless receiver 430 may by assuming that the channel is static or very slow changing. Moreover, the wireless receiver 430 may use the previously measured channel response to perform channel equalization and data detection.

Figure 10 is a flow diagram illustrating a method 1000 for operating the LIS device 410. The method 1000 comprises a first step 1001 of adjusting the respective adjustable reflectivity of each of the one or more reflecting elements 411 a-d of the LIS device 410 as a function of time in accordance with a respective reflectivity pattern. Furthermore, the method 1100 comprises a step 1003 of transmitting reflectivity pattern information, wherein the reflectivity pattern information comprises information about the respective reflectivity pattern of each of the one or more reflecting elements 411 a-d) of the LIS device 410.

Figure 11 is a flow diagram illustrating a method 1100 for determining a location of the wireless transmitter 420. The localization method 1100 comprises a first step 1101 of receiving a plurality of single or multiple reflected RF radiation signals from the wireless transmitter 420. Furthermore, the method 1100 comprises a further step 1103 of obtaining reflectivity pattern information 600 from the LIS device 410, wherein the reflectivity pattern information 600 comprises information 603 about a respective reflectivity pattern of each of the one or more reflecting elements 411 a-d of the LIS device 410, Moreover, the method 1100 comprise a step 1105 of determining based on the reflectivity pattern information 600 and the plurality of single or multiple reflected RF radiation signals from the wireless transmitter 420 the location of the wireless transmitter 420.

The person skilled in the art will understand that the "blocks" ("units") of the various figures (method and apparatus) represent or describe functionalities of embodiments of the present disclosure (rather than necessarily individual "units" in hardware or software) and thus describe equally functions or features of apparatus embodiments as well as method embodiments (unit = step).

In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus, and method may be implemented in other manners. For example, the described embodiment of an apparatus is merely exemplary. For example, the unit division is merely logical function division and may be another division in an actual implementation. For example, a plurality of units or components may be combined or integrated into another system, or some features may be ignored or not performed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections may be implemented by using some interfaces. The indirect couplings or communication connections between the apparatuses or units may be implemented in electronic, mechanical, or other forms.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one position, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the objectives of the solutions of the embodiments.

In addition, functional units in the embodiments of the invention may be integrated into one processing unit, or each of the units may exist alone physically, or two or more units are integrated into one unit.

Claims

1. A large intelligent surface, LIS, device (410), comprising: one or more reflecting elements (411a-d), wherein each reflecting element (411a- d) is configured to reflect a radio frequency, RF, radiation signal received from a wireless transmitter (420) with an adjustable reflectivity; a controller (413) configured to adjust the respective adjustable reflectivity of each of the one or more reflecting elements (411 a-d) overtime in accordance with a respective reflectivity pattern; and a wireless communication interface (415) configured to transmit reflectivity pattern information (600), wherein the reflectivity pattern information (600) comprises information (603) about the respective reflectivity pattern of each of the one or more reflecting elements (411 a-d).

2. The LIS device (410) of claim 1 , wherein the one or more reflecting elements (411 a-d) are arranged in a plane as an array.

3. The LIS device (410) of claim 1 , wherein a first subset of the one or more reflecting elements (411 a-d) is arranged in a first plane as a first array and a second subset of the one or more reflecting elements (411 a-d) is arranged in a second plane as a second array at an angle with respect to the first plane.

4. The LIS device (410) of any one of the preceding claims, wherein, for each reflecting element of the one or more reflecting elements (411 a-d), the reflectivity pattern has a continuous or discrete dependence of the reflectivity of the reflecting element over time.

5. The LIS device (410) of claim 4, wherein, for each reflecting element of the one or more reflecting elements (411 a-d), the reflectivity pattern comprises a first state having a first reflectivity of the reflecting element and a second state having a second reflectivity of the reflecting element.

6. The LIS device (410) of claim 5, wherein the reflectivity patterns of at least two of the one or more reflecting elements (411 a-d) are orthogonal.

7. The LIS device (410) of claim 5 or 6, wherein the one or more reflectivity patterns of the one or more reflecting elements (411a-d) are configured to minimize at least one of a transition from the first state to the second state and a transition from the second state to the first state.

8. The LIS device (410) of any one of the preceding claims, wherein the reflectivity pattern information (600) further comprises information having one or more freeze periods, wherein, during the one or more freeze periods, the reflectivity of each reflecting element of the one or more reflecting elements (411a-d) is constant.

9. The LIS device (410) of any one of the preceding claims, wherein the reflectivity pattern information (600) further comprises information about at least one of a location and an orientation of the LIS device (410).

10. The LIS device (410) of any one of the preceding claims, wherein the reflectivity pattern information (600) further comprises an identifier (601) of the LIS device (410).

11. A wireless receiver (430) for determining a location of a wireless transmitter (420), wherein the wireless receiver (430) comprises: a wireless communication interface (433) configured to receive a plurality of single or multiple reflected radio frequency, RF, radiation signals from a wireless transmitter (420), wherein the wireless communication interface (433) is further configured to obtain reflectivity pattern information (600) from a large intelligent surface, LIS, device (410), wherein the reflectivity pattern information (600) comprises information (603) about a respective reflectivity pattern of each of one or more reflecting elements (411a-d) of the LIS device (410); and a processing circuitry (431) configured to determine, based on the reflectivity pattern information (600) and the plurality of single or multiple reflected RF radiation signals from the wireless transmitter (420), the location of the wireless transmitter (420).

12. The wireless receiver (430) of claim 11 , wherein the processing circuitry (431) is configured to determine the location of the wireless transmitter (420), based on the reflectivity pattern information (600), by determining at least one of the plurality of single or multiple reflected RF radiation signals from the wireless transmitter (420) that has been reflected by the one or more reflecting elements (411a-d) of the LIS device (410).

13. The wireless receiver (430) of claim 11 or 12, wherein the wireless receiver (430) is a wireless base station (430) or a wireless user equipment.

14. A system (400) for determining a location of a wireless transmitter (420), wherein the system (400) comprises: a LIS device (410) according to any one of claims 1 to 10; and a wireless receiver (430) according to any one of claims 11 to 13.

15. A method (1000) for operating a large intelligent surface, LIS, device (410), wherein the LIS device (410) comprises one or more reflecting elements (411a-d), wherein each of the one or more reflecting elements (411a-d) is configured to reflect a radio frequency, RF, radiation signal received from a wireless transmitter (420) with an adjustable reflectivity, wherein the method (1000) comprises: adjusting (1001) the respective adjustable reflectivity of each of the one or more reflecting elements (411 a-d) overtime in accordance with a respective reflectivity pattern; and transmitting (1003) reflectivity pattern information (600), wherein the reflectivity pattern information (600) comprises information (603) about the respective reflectivity pattern of each of the one or more reflecting elements (411 a-d).

16. A method (1100) for determining a location of a wireless transmitter (420), wherein the method (1100) comprises: receiving (1101) a plurality of single or multiple reflected radio frequency, RF, radiation signals from the wireless transmitter (420); obtaining (1103) reflectivity pattern information (600) from a large intelligent surface, LIS, device (410), wherein the reflectivity pattern information (600) comprises information (603) about a respective reflectivity pattern of each of one or more reflecting elements (411 a-d) of the LIS device (410); and determining (1105), based on the reflectivity pattern information (600) and the plurality of single or multiple reflected RF radiation signals from the wireless transmitter (420), the location of the wireless transmitter (420).

17. A computer program product comprising a non-transitory computer-readable storage medium for storing program code which causes a computer or a processor to perform the method (1000) of claim 15 or the method of claim 16 when the program code is executed by the computer or the processor.