EP4285497A1

EP4285497A1 - Apparatus and method for configuring intelligent reflecting surface

Info

Publication number: EP4285497A1
Application number: EP21715842.7A
Authority: EP
Inventors: Richard Stirling-Gallacher; Samer Bazzi; Mario Hernán CASTAÑEDA GARCIA; Malte Schellmann
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2021-03-25
Filing date: 2021-03-25
Publication date: 2023-12-06
Also published as: WO2022199818A1

Abstract

The present disclosure relates to techniques for configuring an intelligent reflecting surface. Particularly, the present disclosure relates to a user device (120, 801a), comprising: a processor (803a), configured to: determine at least one intelligent reflecting surface, IRS, configuration pair of beam and corresponding phase factor, wherein the IRS configuration pair indicates the beam to be formed at the IRS (130) which reflects a signal from a serving and/or from an interfering node, and the phase factor to be applied to the beam formed at the IRS (130); a communication interface (805a) configured to transmit interference cancellation information to the serving node (110a, 820), wherein the interference cancellation information comprises the at least one IRS configuration pair of beam and corresponding phase factor.

Description

Apparatus and method for configuring intelligent reflecting surface

TECHNICAL FIELD

The present disclosure relates to apparatus and method for configuring an intelligent reflecting surface (IRS). In particular, the disclosure relates to techniques for configuring an IRS to maximize a user device’s received SINR (Signal-to-interference and noise ratio).

BACKGROUND

With the recent introduction of IRS, a novel technology has emerged which offers the potential to shape the channel environment according to desired conditions. An IRS is a planar array consisting of a large number of (nearly) passive, low-cost and low energy consuming reflecting elements with reconfigurable parameters. IRS can be used in wireless communications for different purposes. When using IRS in a multi-cell scenario, e.g. as shown in Figure 2, multiple beams are hitting the user device, some of them are serving beams or reflected serving beams, other ones are interfering beams or reflected interfering beams. The performance of the user device deteriorates when a lot of interfering beams or reflections of interfering beams by the IRS hit the user device, resulting in a decrease of the signal-to-interference and noise ratio.

SUMMARY

It is an object of this disclosure to provide techniques for improving the overall signal conditions of one or more user devices, in particularly the user devices at the cell edge, while maintaining a low additional signaling and sounding overhead.

This object is achieved by the features of the independent claims. Further implementation forms are apparent from the dependent claims, the description and the figures.

A basic idea of this disclosure is to let the user equipment (UE), also referred to as user device hereinafter, determine from a set of pre-defined beams (codebook) the beam reflected by the IRS and the corresponding phase factor to maximize a target metric of received signal quality (through a process defined for downlink (DL) estimation). Further, a gain factor is calculated for providing information on the improvement of the signal quality yield by using the reflected IRS beam additionally, which - if signaled to the base station (BS), also referred to as serving node hereinafter, - allows the BS to choose from multiple user devices the one who benefits the most from an additional reflected IRS beam (note that, in general, an IRS can be configured for a single beam per time instance only). The basic concept of this disclosure is the user device determining the configuration of an IRS to maximize a target metric of received signal quality, and signaling this configuration to the serving node in form of one or multiple pairs of configuration parameters, where this pair is constituted of a beam index and a corresponding phase factor. In addition to that, a quality improvement factor (= gain factor) may be determined and signaled, which allows the serving node to select the user device to be supported by the IRS in a given time slot, if many user devices are competing for support.

Two cases are considered: Single-cell and multi-cell.

In the single-cell scenario, the user device determines the pair of configuration parameters (i.e., beam index and phase factor) for the IRS to enable a constructive addition of the beam received from the serving node and the beam reflected by the IRS at the receiving user device, yielding an improvement of the overall channel gain (where the improvement depends on the strength of the reflected IRS beam).

In the multi-cell scenario, the user device determines one or multiple pairs of configuration parameters for the IRS to enable a maximization of the overall SI NR conditions at the receiving user device, taking into account the useful signal (whose direct and reflected IRS beam are supposed to add up constructively) as well as the interfering signal (whose direct and reflected IRS beam are supposed to add up destructively). Thanks to the reduction of interference and increase of useful signal power at the same time, the SINR may be substantially increased by this method.

The key aspects of this disclosure can be described as follows:

A new configuration for the user device is disclosed to report the appropriate configuration of an IRS and the gain with respect to its signal conditions for its communication with the serving node aided by an IRS using a fixed set of beams.

Novel user device measurement reports are disclosed as follows:

A novel configuration of IRS to support user device is disclosed comprising a pair of beam index and phase factor. The phase factor is applied to beams formed at IRS, providing an additional degree of freedom for maximizing the SINR at the user device. More than one pair of beam index and phase factor may be signaled, allowing the BS different choices of IRS configurations. An optional gain factor p may be used to allow BS to select the user device most suited to be supported by IRS (since, in general, only a single IRS beam can be configured at any time slot).

A novel CQI report format is disclosed for the pair of beam index and phase factor, corresponding to one of the following: the overall SINR, including serving, interfering and reflected IRS beams (case 2, see Figure 4); the effective channel gain constituted of direct beam and reflected IRS beam (case 1 , see Figure 3); and the channel gain of the reflected IRS beam (case 1, see Figure 3).

An IRS as described in this disclosure may be a planar array consisting of a large number of (nearly) passive, low-cost and low energy consuming reflecting elements with reconfigurable parameters. Each of these elements reflects an impinging radio wave with an individually configurable phase shift, which results in the formation of a reflection beam, whose direction can be actively controlled by choosing the phase shifts for the reflecting elements accordingly. One or multiple IRSs can be easily integrated into walls or ceilings of large halls and buildings.

An IRS may open up additional channel propagation paths and thus enables shaping the radio channel -- without any increase of the transmit power. This way, it can create additional channel diversity, and it can establish line-of-sight (LOS)-like channel conditions for any communication device residing in the coverage area, thus enabling a better radio illumination of the entire space of radio service. In fact, an IRS acts similar to a relay, but adds no additional latency and does not emit any additional power, thus yielding a significantly improved energy efficiency.

According to a first aspect, the disclosure relates to a user device, comprising: a processor, configured to: determine at least one intelligent reflecting surface, IRS, configuration pair of beam and corresponding phase factor, wherein the IRS configuration pair indicates the beam to be formed at the IRS which reflects a signal from a serving and/or from an interfering node, and the phase factor to be applied to the beam formed at the IRS; a communication interface configured to transmit interference cancellation information to the serving node, wherein the interference cancellation information comprises the at least one IRS configuration pair of beam and corresponding phase factor.

Such user device is able to efficiently configure an IRS to improve the signal conditions at the user device, which may be especially beneficial for cell-edge users experiencing weak signal conditions. By such configuration of IRS, a significant improvement at little cost in additional signaling can be achieved, since only a pair of configuration parameters, namely the beam index and corresponding phase factor, needs to be signaled to the serving node, and optionally the quality improvement factor p, allowing the serving node to choose from different user devices the one benefitting the most from the IRS support.

In an embodiment of the user device, the interference cancellation information further comprises at least one of: a gain factor p, a channel quality indicator, CQI, of a channel shaped by the IRS according to the IRS configuration pair, a beam index of the beam.

This provides the advantage that the relevant parameters required for configuration of the IRS are transmitted to the serving node.

In an embodiment of the user device, the phase factor is selected from a set of discrete values, and a range of the discrete values is [0, 2p]

This provides the advantage that only a limited set of supported phase factors have to be transmitted to the serving node, resulting in an efficient resource usage for the signaling.

In an embodiment of the user device, the communication interface is configured to receive a response of interference cancellation information.

This provides the advantage that the user device is informed if the transmitted interference cancellation information has successfully reached the serving node and whether it will be applied at the IRS.

In an embodiment of the user device, determining the at least one IRS configuration pair of beam and corresponding phase factor is based on a channel coefficient of a serving beam of the serving node directed towards the user device and/or a channel coefficient of an interfering beam of the interfering node covering the user device.

This provides the advantage that information about the serving beam and the interfering beam can be used for an optimal configuration of the IRS.

In an embodiment of the user device, determining the at least one IRS configuration pair of beam and corresponding phase factor is based on channel coefficients of a number of reflection beams formed at the IRS and fed by the serving beam, and/or channel coefficients of the number of reflection beams formed at the IRS and fed by the interfering beam. The IRS forms one set of beams, and these beams reflect the serving and interfering beams from the BSs in a different manner, yielding the different channel coefficients.

Note that the reflection beams formed by the IRS are the same, but the channel coefficients are different, since they are fed by different incoming beams.

This provides the advantage that information about the reflection beams can be used for determining an optimal configuration of the IRS.

In an embodiment of the user device, determining the at least one IRS configuration pair of beam and corresponding phase factor is based on a target metric calculated from the determined channel coefficients of the serving beam and the number of reflection beams fed by the serving beam and/or the determined channel coefficients of the interfering beam and the number of reflection beams fed by the interfering beam.

This provides the advantage that the target metric can be used for an optimal configuration of the IRS.

In an embodiment of the user device, the at least one IRS configuration pair of beam and corresponding phase factor are maximizing the target metric.

A beam is a directional shaping of a radio wave radiated from an antenna or antenna array. A reflection beam is formed by individually configured phase shifts of the antenna elements at an IRS, shaping the direction of a radio wave impinging at the IRS. Each formed beam given by a predefined set can be identified by a characteristic number that is also referred to as the beam index.

This provides the advantage that parameters maximizing the target metric can be used for an optimal configuration of the IRS.

In an embodiment of the user device, the target metric comprises a signal-to-interference and noise ratio based on the determined channel coefficients of the serving beam and the number of reflection beams fed by the serving beam and/or the determined channel coefficients of the interfering beam and the number of reflection beams fed by the interfering beam. This provides the advantage that the channel coefficients of the serving beam and the channel coefficients of the interfering beam can be used for determining an optimal configuration of the IRS.

In an embodiment of the user device, the user device is configured with a threshold, and the user device is triggered to send the IRS configuration pair based on the threshold.

The target metric described above may be configured or predefined. If it is preconfigured by the network or predefined by standard or preconfigured by user device itself, the user device can check this given target metric against a threshold.

The threshold may be predefined, e.g. configured by network or predefined by standard.

This provides the advantage of a resource-saving computation of an optimal configuration of the IRS.

In an embodiment of the user device, the target metric is based on a signal power of the channel coefficient of the serving beam and a number of channel coefficients of the reflection beams fed by the serving beam, each reflection beam being phase shifted by a respective phase-factor of a predetermined set of phase factors; and/or the target metric is further based on an interference power of the channel coefficient of the interfering beam and a number of channel coefficients of the reflection beams fed by the interfering beam, each reflection beam being phase shifted by the respective phase-factor of the predetermined set of phase factors. Note that there is only one phase factor that can be chosen for the IRS configuration.

This usage of the phase shift provides an additional parameter for maximizing the target metric to yield an optimal SINR at the user device. As mentioned above, there is only one phase factor to be determined at the IRS.

The time slot for determining the channel coefficient of the serving beam and the channel coefficient of the interfering beam may be a pre-defined time slot in which the IRS is switched off, and correspondingly there is no reflection of the serving beam and the interfering beam at the IRS. Each reflection beam may correspond to a beamforming vector formed by the IRS, the beamforming vector shaping a reference signal transmitted by the serving node and/or interfering node with a spatial filter. In an embodiment of the user device, the number of reflection beams fed by the serving beam and the number of reflection beams fed by the interfering beam are received from the IRS within a number of successive time slots, each reflection beam fed by the serving beam and each reflection beam fed by the interfering beam obtained within a respective time slot of the number of successive time slots.

This provides the advantage of a fast estimation of the reflection beams and fast determination of an optimal configuration of the IRS within a few time slots.

The beams are received by the user device, and the channel coefficients of the beams are obtained based on the reference signals reflected by the IRS.

Each reflection beam fed by the serving beam and each reflection beam fed by the interfering beam received within the number of successive time slots is phase-shifted with a phase factor of zero.

The processor may be configured to determine a channel coefficient of a respective reflection beam fed by the serving beam and a channel coefficient of a respective reflection beam fed by the interfering beam based on a channel coefficient of a sum beam corresponding to a superposition of the serving beam, the interfering beam, the respective reflection beam fed by the serving beam and the respective reflection beam fed by the interfering beam.

According to a second aspect, the disclosure relates to a serving node for serving a user device, the serving node comprising: a communication interface, configured to receive interference cancellation information from the user device, wherein the interference cancellation information comprises at least one intelligent reflecting surface, IRS, configuration pair of beam and corresponding phase factor, wherein the IRS configuration pair of beam and corresponding phase factor indicates a beam to be formed at the IRS which reflects a signal from the serving node and/or from an interfering node, and a phase factor to be applied to the beam formed at the IRS; and a processor configured to signal an instruction message to the IRS, the instruction message instructing the IRS to form a beam according to the at least one IRS configuration pair of beam and corresponding phase factor.

Such a serving node can efficiently configure an IRS to improve the signal conditions at the user device, which may be especially beneficial for cell-edge users experiencing weak signal conditions. By such configuration of IRS, a significant improvement at little cost in additional signaling can be achieved, since only a pair of configuration parameters, namely the beam index and corresponding phase factor, needs to be signaled to the serving node, and optionally the quality improvement factor p, allowing the serving node to choose from different user devices the one benefitting the most from the IRS support.

In an embodiment of the serving node, the interference cancellation information further comprises at least one of: a gain factor p, a channel quality indicator, CQI, of a channel shaped by the IRS according to the IRS configuration pair, a beam index of the beam, at least one other pair of beam and corresponding phase factor.

In an embodiment of the serving node, the phase factor is selected from a set of discrete values, and a range of the discrete values is [0, 2p]

In an embodiment of the serving node, the communication interface is configured to transmit a response of interference cancellation information to the user device.

In an embodiment of the serving node, the at least one IRS configuration pair of beam and corresponding phase factor is used to maximize a target metric at a corresponding user device.

In an embodiment of the serving node, the target metric comprises a signal-to-interference and noise ratio based on channel coefficients of a serving beam of the serving node directed towards the user device and a number of reflection beams formed at the IRS and fed by the serving beam, and / or the channel coefficients of an interfering beam of the interfering node covering the user device and the number of reflection beams formed at the IRS and fed by the interfering beam. This provides the advantage that the channel coefficients of the serving beam and the channel coefficients of the interfering beam can be used for determining an optimal configuration of the IRS.

In an embodiment of the serving node, the processor is configured to instruct the IRS to switch off reflection of the serving beam and the interfering beam in a pre-defined time slot in order to enable the user device determining the channel coefficient of the serving beam and the channel coefficient of the interfering beam.

This provides the advantage that the user device is enabled to estimate the serving beam and the interfering beam without disturbing reflections from the IRS.

In an embodiment of the serving node, the communication interface is configured to transmit a reference signal to the IRS within each of a number of successive time slots in order to enable the IRS to form a respective reflection beam within each time slot.

This provides the advantage that the reflection beams can be estimated at the user device, and an optimal configuration of the IRS can be determined by the user device after a few number of time slots.

According to a third aspect, the disclosure relates to a method for transmitting interference cancellation information to a serving node, the method comprising: determining, by a user device, at least one intelligent reflecting surface, IRS, configuration pair of beam and corresponding phase factor, wherein the IRS configuration pair indicates the beam to be formed at the IRS which reflects a signal from a serving and/or from an interfering node, and the phase factor to be applied to the beam formed at the IRS; and transmitting, by the user device, interference cancellation information to the serving node, wherein the interference cancellation information comprises the at least one IRS configuration pair of beam and corresponding phase factor.

Such a method provides the same advantages as the user device according to the first aspect described above.

According to a fourth aspect, the disclosure relates to a method for instructing an intelligent reflecting surface, IRS, to form a beam, the method comprising: receiving, by a serving node, interference cancellation information from a user device, wherein the interference cancellation information comprises at least one IRS configuration pair of beam and corresponding phase factor, wherein the IRS configuration pair of beam and corresponding phase factor indicates a beam to be formed at the IRS which reflects a signal from the serving node and/or from an interfering node, and a phase factor to be applied to the beam formed at the IRS; and signaling, by the serving node, an instruction message to the IRS, the instruction message instructing the IRS to form a beam according to the at least one IRS configuration pair of beam and corresponding phase factor.

Such a method provides the same advantages as the serving node according to the second aspect described above.

According to a fifth aspect, the disclosure relates to a computer program product including computer executable code or computer executable instructions that, when executed, causes at least one computer to execute the method according to the third or fourth aspect.

Such a computer program product may include a non-transient readable storage medium storing program code thereon for use by a processor, the program code comprising instructions for performing the methods or the computing blocks as described hereinafter.

The computer program product may run on the components of a communication system described below with respect to Figure 8. For example, the computer program product may run on a user device 801a as shown in Figure 8. Such a user device may comprises a processing circuitry 803a for instance, a processor 803a, for processing and generating data, e.g. the program code described above, a transceiver 805a, including, for instance, a transmitter, a receiver and an antenna, for exchanging data with the other components of the communication system 800, and a non-transitory memory 807a for storing data, e.g. the program code described above.

For example, the computer program product may run on a serving node or base station 820 as shown in Figure 8. Such a serving node 820 may comprises a processing circuitry 813 for instance, a processor 813, for processing and generating data, e.g. the program code described above, a transceiver 815, including, for instance, a transmitter, a receiver and an antenna, for exchanging data with the other components of the communication system 800, and a non-transitory memory 817 for storing data, e.g. the program code described above. Both memories 807a and 817 can include non-transitory machine-readable storage media, i.e. storage media that store code in a non-transitory way for a specific amount of time and which media can be read by the corresponding processor 803a, 813. Such non-transitory machine- readable storage media may be a RAM, a ROM, an EPROM or an EEPROM for example.

Using such a computer program product improves efficiency of determining SINR at the user device.

BRIEF DESCRIPTION OF THE DRAWINGS

Further embodiments of the invention will be described with respect to the following figures, in which:

Fig. 1 shows a wireless communication system 100 using IRS;

Fig. 2 shows a schematic diagram illustrating an exemplary multi-cell scenario 200a, 200b where user device is located at cell edge;

Fig. 3 shows a schematic diagram illustrating an exemplary single-cell scenario 300 with beam addition at user device and determination of IRS configuration at user device for constructive beam addition;

Fig. 4 shows a schematic diagram illustrating an exemplary multi-cell scenario 400 with interference from adjacent cell at user device and determination of IRS configuration at user device;

Fig. 5 shows an exemplary message sequence chart 500 for the multi-cell scenario;

Fig. 6 shows a schematic diagram illustrating a method 600 for transmitting interference cancellation information to a serving node;

Fig. 7 shows a schematic diagram illustrating a method 700 for instructing an IRS by a serving node to form a beam; and

Fig. 8 shows a schematic diagram illustrating a communication system. DETAILED DESCRIPTION OF EMBODIMENTS

In order to describe the invention in detail, the following terms, abbreviations and notations will be used:

UE User Equipment, also referred to as user device

BS Base Station, also referred to as serving node or interfering node, respectively

IRS Intelligent Reflecting Surface

BFV Beamforming Vector

SI NR Signal-to-interference and noise ratio

CQI Channel quality indicator loT Internet of Things

LOS line-of-sight

TDM time division multiplex

RS reference signal

UL uplink

DL downlink

In the following detailed description, reference is made to the accompanying drawings, which form a part thereof, and in which are shown by way of illustration specific aspects in which the disclosure may be practiced. It is understood that other aspects may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. 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.

It is understood that comments made 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 a specific method step is described, a corresponding device may include a unit to perform the described method step, even if such unit is not explicitly described or illustrated in the figures. Further, it is understood that the features of the various exemplary aspects described herein may be combined with each other, unless specifically noted otherwise.

The methods, devices and systems described herein may be implemented in wireless communication schemes, in particular communication schemes according to 5G or beyond. The described devices may include integrated circuits and/or passives and may be manufactured according to various technologies. For example, the circuits may be designed as logic integrated circuits, analog integrated circuits, mixed signal integrated circuits, optical circuits, memory circuits and/or integrated passives. The devices described herein may be configured to transmit and/or receive radio signals. Radio signals may be or may include radio frequency signals radiated by a radio transmitting device (or radio transmitter or sender). However, devices described herein are not limited to transmit and/or receive radio signals, also other signals designed for transmission in deterministic communication networks may be transmitted and/or received.

The devices and systems described herein may include processors or processing devices, memories and/or transceivers, i.e. transmitters and/or receivers. The term “processor” or “processing device” describes any device that can be utilized for processing specific tasks (or blocks or steps). A processor or processing device can be a single processor or a multi-core processor or can include a set of processors or can include means for processing. A processor or processing device can process software or firmware or applications etc.

The devices and systems described herein may include transceivers or transceiver devices. A transceiver is a device that is able to both transmit and receive information through a transmission medium, e.g. a radio channel. It is a combination of a transmitter and a receiver, hence the name transceiver. Transmission is usually accomplished via radio waves. By combining a receiver and transmitter in one consolidated device, a transceiver allows for greater flexibility than what either of these could provide individually.

The devices and systems described herein may include intelligent reflecting surfaces (IRSs). An IRS comprises an array of reflecting elements, each of which can independently incur some change to the incident signal. The change in general may be about the phase, amplitude, frequency, or even polarization. In most implementations, the change is considered as a phase shift only to the incident signal, so that an IRS consumes no transmit power. In essence, an IRS intelligently configures the wireless environment to support the transmissions between the sender and receiver, when direct communications between them have insufficient qualities. Example places to put IRSs are walls, building facades, and ceilings.

Fig. 1 shows a wireless communication system 100 using IRS.

With the recent introduction of an intelligent reflecting surface (IRS), a novel technology has emerged which offers the potential to shape the channel environment according to desired conditions. An IRS 130 represents a new communication entity for wireless networks which has high potential for significantly reducing overall energy consumption while realizing Massive MIMO gains.

An IRS may be a planar array consisting of a large number of (nearly) passive, low-cost and low energy consuming reflecting elements with reconfigurable parameters. Each of these elements may reflect an impinging radio wave with an individually configurable phase shift, which results in the formation of a reflection beam, whose direction can be actively controlled by choosing the phase shifts for the reflecting elements accordingly. The purpose of IRS may be to make the propagation channel more favorable for the users. One or multiple IRSs can be easily integrated into walls or ceilings of large halls and buildings.

IRSs can be used in wireless communications for different purposes, for example: Reaching users in dead zones as shown in Figure 1, where a wall 140 blocks direct communication between serving node 110 and user device 120. Another interesting purpose is given by the use of an IRS deployed close to the cell edge as shown in Figure 2, which can help any user device at cell edge to improve its signal conditions for transmission and reception.

Further, IRSs are highly promising for loT applications, as they can support focusing the transmit power into the direction of low-power user devices and - in the favorable case - establishing LOS-like communication links to them. Typically, an IRS may have several hundred antenna elements, enabling the formation of highly directive and focused beams and yielding high antenna gains. Reflection beams are formed by (predefined) sets of phase shifts applied to the antenna elements, which can be configured and controlled by the base station. For this purpose, an IRS houses a controller, which is directly connected to the base station (both wireline and wireless connections are possible).

A controller may be used at each IRS to configure the phase shifts of the antenna elements at the IRS, or to switch off the IRS entirely. The controller may be connected to the base station 110 either wirelessly (through a UE device type or user device type) or by wireline.

Fig. 2 shows a schematic diagram illustrating an exemplary multi-cell scenario 200a, 200b where user device is located at cell edge.

In the multi-cell scenario 200a on the left of Figure 2, IRSs 130 are deployed at the cell corners of the multi-cell grid. Note that in the context of Figure 2, the reference sign 130 represents a triangle of a total of 3 IRSs, where each IRS can be used for a distinct pair of adjacent BSs from the cell cluster consisting of 3 BSs in total. The orientation of the IRS plane should be along the connection between two adjacent base stations, e.g. BS_n and BS_n+i, resulting in a triangular setup of IRSs at the cell corner. Following this setup, an IRS 130 can reflect signals from adjacent cells, which may be used to improve the SI NR of a user device located at cell edge between those two adjacent cells.

A more detailed illustration of the communication conditions between the base stations 110a, 110b of the adjacent cells and a cell edge user device 120 supported by the IRS 130 at the cell corner is given by the multi-cell scenario 200b on the right of Figure 2. BS_n is the serving base station 110a, that serves the cell-edge user device 120: a) directly on its serving beam 111a and b) indirectly on a beam 113a reflected by the IRS 130 (denoted as reflected serving beam b_x,n), which is fed by the sidelobes 112a of BS_n’s 110a serving beam 111a.

Similarly, there is interference from neighboring base station BS_n+i, 110b, which hits the cell edge user device 120: a) directly by an interfering beam 111b (or its sidelobes 112b) formed by the neighboring BS_n+i 110b to serve another user device; and b) indirectly by a beam 113b reflected by the IRS 130 (denoted as reflected interfering beam b_x ), which is fed by BS_n+i’s 110b interfering beam 111b or its sidelobes 112b.

In the following, functionality of the user device 120 and the serving node 110a are described in more detail to support this basic concept of the disclosure. The user device 120 and the serving node 110a may both comprise a processor 803a, 813, a transceiver 805a, 815 and a memory 807a, 817 as exemplarily shown in the communication system 800 described with respect to Figure 8.

The user device 120 and the serving node 110a may be implemented as described in the communication system 800 of Figure 8, i.e. the user device 120, 801a may comprise a processor 803a, a transceiver 805a or communication interface, respectively, and a memory 807a. The serving node 110a, 820 or base station, respectively, may comprise a processor 813, a transceiver 815 or communication interface, respectively, and a memory 817.

The user device 120 comprises a processor 803a, configured to: determine at least one intelligent reflecting surface, IRS, configuration pair of beam and corresponding phase factor, wherein the IRS configuration pair indicates the beam to be formed at the IRS 130, which reflects a signal from a serving and/or from an interfering node, and the phase factor to be applied to the beam formed at the IRS 130. The user device 120 may comprise a communication interface 805a configured to transmit interference cancellation information to the serving node 110a, 820, wherein the interference cancellation information comprises the at least one IRS configuration pair of beam and corresponding phase factor.

The interference cancellation information may further comprises at least one of: a gain factor p, a channel quality indicator, CQI, of a channel shaped by the IRS according to the IRS configuration pair, a beam index of the beam.

The phase factor may be selected from a set of discrete values, and a range of the discrete values is [0, 2p]

The communication interface 805a may be configured to receive a response of interference cancellation information.

Determining the at least one IRS configuration pair of beam and corresponding phase factor may be based on a channel coefficient (b_n) of a serving beam of the serving node 110a, 820 directed towards the user device 120, 801a and/or a channel coefficient (b,) of an interfering beam of the interfering node 110b covering the user device 120, 801a.

Determining the at least one IRS configuration pair of beam and corresponding phase factor may be based on channel coefficients (b_x,n) of a number of reflection beams (x) formed at the IRS 130 and fed by the serving beam, and/or channel coefficients (b_x ) of the number of reflection beams (x) fed by the interfering beam.

The IRS may form one set of beams, and each of these beams reflects the serving and interfering beam from the two BSs in a different manner, yielding the different channel coefficients for the reflected serving (b_x,n) and interfering beam (b_x ), respectively.

Determining the at least one IRS configuration pair of beam and corresponding phase factor may be based on a target metric calculated from the determined channel coefficients (b_n, b_x,n) of the serving beam and the number of reflection beams fed by the serving beam and/or the determined channel coefficients (b,, b_x ) of the interfering beam and the number of reflection beams fed by the interfering beam.

The at least one IRS configuration pair of beam and corresponding phase factor may maximize the target metric at the user device 120. A beam may be defined as a directional shaping of a radio wave radiated from an antenna or antenna array. A reflection beam is formed by individually configured phase shifts of the antenna elements at an IRS, shaping the direction of a radio wave impinging at the IRS. Each formed beam given by a predefined set can be identified by a characteristic number that is also referred to as the beam index.

The target metric may comprise a signal-to-interference and noise ratio based on the determined channel coefficients (b_n, b_x,n) of the serving beam and the number of reflection beams fed by the serving beam and/or the determined channel coefficients (b,, b_x ) of the interfering beam and the number of reflection beams fed by the interfering beam.

The user device 120, 801a may be configured with a threshold, and the user device 120, 801a may be triggered to send the IRS configuration pair based on the threshold.

The target metric may be based on a signal power of the channel coefficient (b_n) of the serving beam and a number of channel coefficients (b_x,n) of the reflection beams (x) fed by the serving beam, each reflection beam being phase shifted by a respective phase-factor of a predetermined set of phase factors; and/or the target metric may be further based on an interference power of the channel coefficient (b,) of the interfering beam and a number of channel coefficients (b_x ) of the reflection beams (x) fed by the interfering beam, each reflection beam being phase shifted by the respective phase-factor of the predetermined set of phase factors. Note that there is only one phase factor that can be chosen for the IRS configuration.

The time slot for determining the channel coefficient (b_n) of the serving beam and the channel coefficient (b,) of the interfering beam may be a pre-defined time slot in which the IRS is switched off and correspondingly there is no reflection of the serving beam and the interfering beam at the IRS. Each reflection beam (x) may correspond to a beamforming vector formed by the IRS, the beamforming vector shaping a reference signal transmitted by the serving node and/or interfering node with a spatial filter.

The number of reflection beams (x) fed by the serving beam and the number of reflection beams (x) fed by the interfering beam may be received from the IRS within a number of successive time slots, each reflection beam (x) fed by the serving beam and each reflection beam (x) fed by the interfering beam obtained within a respective time slot of the number of successive time slots.

Each reflection beam (x) fed by the serving beam and each reflection beam (x) fed by the interfering beam received within the number of successive time slots is phase-shifted with a phase factor of zero.

The processor may be configured to determine a channel coefficient (b_x,n) of a respective reflection beam (x) fed by the serving beam and a channel coefficient (b_x ) of a respective reflection beam (x) fed by the interfering beam based on a channel coefficient (b_s) of a sum beam corresponding to a superposition of the serving beam, the interfering beam, the respective reflection beam (x) fed by the serving beam and the respective reflection beam (x) fed by the interfering beam.

The serving node 110a, 820 may comprise a communication interface 815, configured to receive interference cancellation information from the user device 120, 801a, wherein the interference cancellation information comprises at least one intelligent reflecting surface, IRS, configuration pair of beam and corresponding phase factor, wherein the IRS configuration pair of beam and corresponding phase factor indicates a beam to be formed at the IRS 130 which reflects a signal from the serving node 110a, 820 and/or from an interfering node 110b, and a phase factor to be applied to the beam formed at the IRS.

The serving node 110a, 820 may comprise a processor 813 configured to signal an instruction message to the IRS, the instruction message instructing the IRS to form a beam according to the at least one IRS configuration pair of beam and corresponding phase factor.

The interference cancellation information may further comprise at least one of: a gain factor p, a channel quality indicator, CQI, of a channel shaped by the IRS according to the IRS configuration pair, a beam index of the beam, at least one other pair of beam and corresponding phase factor.

The phase factor may be selected from a set of discrete values, and a range of the discrete values is [0, 2p] The communication interface 815 may be configured to transmit a response of interference cancellation information to the user device 120, 801a.

The at least one IRS configuration pair of beam and corresponding phase factor may maximize the target metric at the user device.

The target metric may comprise a signal-to-interference and noise ratio based on channel coefficients (b_n, b_x,n) of a serving beam of the serving node 110a, 820 directed towards the user device 120, 801a and a number of reflection beams formed at the IRS and fed by the serving beam, and / or the channel coefficients (b,, b_x ) of an interfering beam of the interfering node 110b covering the user device 120, 801a and the number of reflection beams fed by the interfering beam.

The processor 813 may be configured to instruct the IRS 130 to switch off reflection of the serving beam and the interfering beam in a pre-defined time slot in order to enable the user device 120, 801a determining the channel coefficient (b_n) of the serving beam and the channel coefficient (b,) of the interfering beam.

The communication interface 815 may be configured to transmit a reference signal to the IRS within each of a number of successive time slots in order to enable the IRS 130 to form a respective reflection beam within each time slot.

Case 1

Fig. 3 shows a schematic diagram illustrating an exemplary single-cell scenario 300 with beam addition at user device and determination of IRS configuration at user device for constructive beam addition.

In the single-cell scenario 300, the communication system may include a base station (BS_n), also referred to as serving node 110a, a user device 120, also referred to as UE, and an IRS 130. The serving node 110a may form a serving beam b_n 111 a directed to the user device 120 and a sidelobe serving beam 112a directed to IRS 130, formed by the sidelobes of the serving beam. IRS 130 forms a reflected beam b2_,n 113a directed to the user device 120.

In this single-cell scenario 300, also referred to as “Case 1”, the existence of serving and reflected beam results in beam addition at user device 120. This beam addition is constructive if the appropriate configuration according to the IRS configuration pair is applied at the IRS. Each beam formed at IRS 130 by a (pre-defined) set of phase shifts (i.e. , the set constituting a beam codebook) is multiplied additionally by a phase factor f, applied directly at the IRS 130. The following process describes how the BS 110a can obtain the required info to configure the IRS for enabling constructive beam addition.

K beams may be formed at IRS are measured by the user device (K=4 in Figure 3): BS_n transmits a reference signal (RS) in each of K successive time slots, whereby IRS switches the beam x e [1 ,K] in each time slot (note that stationarity is assumed during the entire process). During RS transmission, beam x e [1 ,K] is configured with phase factor f = 0, enabling estimation of the sum beam b_s = [reflected beam b_x,n + serving beam b_n] at user device. Serving beam b_n can be measured by using an additional time slot of RS transmission where either the IRS is switched off, or where IRS beam x is configured with phase shift f = p and the user device adds this received beam to received beam x configured with f = 0 from the earlier time slot. Subtracting the measured serving beam b_n from the sum beam b_s then yields the channel for reflected beam b_x,n.

For any beam b_x,n , user device can determine the phase shift yielding constructive addition with serving beam b_n. Thus, choosing the beam index x maximizing the norm of the constructively added beams yields the maximized channel gain (=target metric): where b_n and b_x,n represent the measured complex channel responses of serving and reflected beam, respectively. The effective channel gain g may then be used for channel quality indicator (CQI) quantization. If serving beam b_n is known at BS_n (e.g., from prior UL measurements), the channel gain of b_x,n may be used for CQI quantization alternatively.

It may be useful to provide a gain factor for the contribution of the IRS beam on g, allowing a selection of the user device to be supported by the IRS (since, in general, only a single beam can be configured at the IRS at a time). A factor p indicating b_x,n‘s power contribution to g can be easily computed and quantized as follows:

The user device signals beam index x and the corresponding phase shift Q to BS_n, which configures the IRS accordingly. Additionally, the user device can signal: CQI corresponding to the effective channel gain g; CQI corresponding to the channel gain of the reflected beam b_x,n; (quantized) gain factor p.

Besides judging the value of IRS beam, p may further allow the BS to determine the channels of b_n and b_x,n from the sum beam b_s = [b_n + e^je b_{x n}\ measured during UL transmission by the following formula:

The exact knowledge of b_n and b_x,n at BS_n may be useful and beneficial for further optimization driven by the BS.

The separation based on p as given by the above formula is possible thanks to the coherent addition of b_n and b_x,n . Note, however, that the coarser is quantized, the more inaccurate this separation may become.

Case 2

Fig. 4 shows a schematic diagram illustrating an exemplary multi-cell scenario 400 with interference from adjacent cell at user device and determination of IRS configuration at user device according to the disclosure.

In the multi-cell scenario 400, the communication system may include a serving base station (BS_n), also referred to as serving node 110a, an interfering base station (BS,), also referred to as interfering node 110b, a user device 120, also referred to as UE, and an IRS 130. The serving node 110a may form a serving beam b_n 111a directed to the user device 120 and a sidelobe serving beam 112a directed to IRS 130, formed by the sidelobes of the serving beam. The interfering node 110b may form an interfering beam b 111b covering the user device 120 and a sidelobe interfering beam 112b directed to IRS 130, formed by the interfering beam and/or its sidelobes. IRS 130 may form a reflected serving beam b2_,n 113a and a reflected interfering beam b2 113b, both covering the user device 120.

In this multi-cell scenario 400, also referred to as “Case 2”, user device receives interference from adjacent BS 110b and performs maximization of SINR as described in the following.

For the multi-cell case with two adjacent BSs 110a, 110b, the following assumptions are made: Serving (b_n) and interfering beam (b,) are provided by a coordinated beamforming scheme between the base stations 110a, 110b ignoring the IRS 130 (or before the IRS 130 is activated). The use of orthogonal pilots preference signals) allows the user device 120 to measure b_n and bi simultaneously, i.e., if the two BSs transmit their orthogonal RS during the same time slot.

Compared to case 1 , the interference from the interfering BS, 110b needs to be taken into account, which impacts the estimation process as well as the target metric to be maximized at the user device 120. The process for finding the proper IRS configuration is adapted as follows:

K beams formed at IRS 130 are measured by the user device 120: (K=4 in Figure 4).

BS_n and BS, transmit RSs in each of K successive time slots, whereby IRS switches the beam x e [1 ,K] in each time slot (note that stationarity is assumed during the entire process).

During RS transmission, beam e [1 , K] is configured with phase factor f = 0, enabling estimation of the sum beam b_s = [reflected b_x,n/i + serving / interfering b_n/i ] at user device.

Serving/interfering beam b_n/i can be measured by using an additional time slot of RS transmission where either the IRS is switched off, or where IRS beam x is configured with phase shift f = p and the user device adds this received beam to received beam x configured with f = 0 from the earlier time slot.

Subtracting the measured serving beam b_n and interfering beam b, from sum beam b_s then yields the channels for the reflected beams b_x,n/i .

For all measured beams b_x,n/i , user device can determine IRS beam index x and phase shift Q maximizing the SI NR (= target metric) where b_n/i and b_x,n/i represent the measured complex channel responses of serving/interfering and reflected beams, respectively. The SINR p based on the effective serving and interfering channels may then be quantized according to CQI values.

A gain factor for the contribution of the IRS beam can then be given as the SINR gain which specifies the improvement compared to the SINR based on solely the serving and interfering beam.

The user device may signal the beam index x and the corresponding phase shift Q to BS_n, which configures the IRS accordingly.

Alternatively, the user device may signal different pairs of (c,q), allowing for different choices of beams

(e.g., yielding SINR improvement above a threshold).

Additionally, user device can signal: CQI corresponding to the overall SINR p; (quantized) SINR improvement represented by p.

If BS, 110b changes its beam, but user device 120 remains static, it may be sufficient for the user device 120 to estimate only the interfering beam b, and its reflection by (pre-selected) beam x:

Recalculate the SINR and the gain P based on Q only:

Signal the updated 6> (and SINR improvement p) to BS_n.

Case 2b

In an alternative implementation of this multi-cell scenario 400, also referred to as “Case 2b”, the estimation is done in the uplink (UL), which means all measurements and estimates will be performed by the BSs or the network, and correspondingly no signaling on the radio link (i.e., between user device and BS) is necessary. The user device’s only duty in this case is the transmission of RS signals. SINR maximization is performed by network as described in the following.

In UL, BS_n & BS, 110a, 110b measure channels from user device 120 and jointly determine IRS configuration.

The user device 120 transmits its RS either omni-directionally or in the direction of BS_n .

K beams may be formed at IRS 130 are measured by BS_n and BS, based on RS transmitted by the user device: (K=4 in Figure 4).

The user device 120 may transmit a RS in each of K successive time slots (as configured by BS_n), whereby IRS 130 switches the beam x e [1 ,K] in each time slot (note that stationarity is assumed during the entire process). During RS transmission, beam x e [1 ,K] is configured with phase factor f = 0, enabling estimation of sum channel c_s = [c_x,_n/i of beam index x + serving / interfering c_n/i ] at BS_n/i.

Serving/interfering c_n/i can be measured by using an additional time slot of RS transmission where either the IRS 130 is switched off or where where IRS beam x is configured with phase shift f = p and any of the BSs adds this received beam to received beam x configured with f = 0 from the earlier time slot.

Subtracting the measured serving/interfering c_n/i from sum channel c_s then yields the channels for IRS beams c_x,_n/i.

With the measured channels, BSs can determine for any serving beam b_n (and interfering beam b,) the signal fraction transferred via IRS beam index x to the user device by the product bx_,n — ^cx_,TnP_{n 3f} ^"id _c,ί — ^cx_,ibi , respectively.

After exchanging the complex channel responses of serving/interfering and reflected beams between BS_n and BS,, BSs can jointly determine the IRS beam index x and phase shift Q maximizing SINR (= target metric): This process controlled jointly by the BSs also allows for solving the optimization problem to find the optimized serving and interfering beam b_n and b,.

BS_n or BSi configures IRS beam index x and phase shift Q.

If BSi wants to change its beam, but user device remains static, a new configuration can be calculated and configured by both BSs at any time, since the measured channels of the IRS beams do not change while the user device is static, i.e., no additional measurement is necessary.

Fig. 5 shows an exemplary message sequence chart 500 for the multi-cell scenario. The message sequence chart 500 refers to the above described multi-cell scenario according to Case 2, where user device 120 determines the IRS configuration.

The message sequence chart 500 represents a signaling diagram illustrating a potential implementation in a cellular communication system. As a prerequisite for the solution to work is that the BSs 110a, 110b as well as the IRS 130 are well synchronized to enable a beam switching at all three entities synchronous with the symbol clock.

The message sequence may comprise the following messages:

501 : RS transmission with IRS switched off from serving BS 110a to user device 120;

502: RS transmission with IRS switched off from interfering BS 110b to user device 120;

503: User device 120 estimate serving and interfering beam;

504: Configure K beams for RS transmission from serving BS 110a to IRS 130;

505: K times RS transmission with beam switching at IRS from serving BS 110a to user device 120;

506: K times RS transmission with beam switching at IRS from interfering BS 110b to user device 120;

507: Estimate reflected serving and interfering beams at user device 120;

508: Evaluate target metric and determine IRS configuration pair (beam and phase), gain factor; CQI for IRS enhanced channel at user device 120;

509: transmit IRS configuration pair(s), CQI and (optionally) gain factor from user device 120 to serving BS 110a;

510: Select appropriate IRS configuration pair from user device feedback at serving BS 110a; 511 : configure IRS with selected configuration pair from serving BS 110a to IRS 130;

512: adapt data rate according to improved CQI at serving BS 110a;

513: data transmission from serving BS 110a to user device 120; 514: data transmission from interfering BS 110b to another user device which results in interference to user device 120.

The steps above are an example and sequence may be different in an implementation. The step above may be optional in an implementation, which is out of the scope of this disclosure.

To allow the user device 120 estimating 503 the channels for the serving beam from the serving BS 110a and for the interfering beam from the interfering BS 110b, both BSs may send orthogonal reference signals (RS) 501, 502 while the IRS 130 is switched off. Thereafter, the serving BS 110a configures 504 the IRS 130 for K different reflection beams, where each of these beams is constituted of a unique set of phase shifts to be applied to the antenna elements of the IRS.

Serving and interfering BS then may transmit 505, 506 their orthogonal RS in K successive time slots, while the IRS 130 will switch between the K configured beams over these K time slots. This way, the user device 120 can estimate 507 the reflected serving and the reflected interfering beams.

Once all beams have been estimated, the user device 120 may evaluate 508 the target metric for all beams and all supported phase factors to determine the IRS configuration pair(s) of beam and corresponding phase factor that maximizes the target metric.

Once the IRS configuration pair(s) is determined, the user device 120 calculates the gain factor p and the CQI for the IRS enhanced channel (i.e. , the SINR based on the effective channels formed by the sum of direct and reflected serving and interfering channels, respectively).

After quantizing IRS configuration pair(s), gain factor and CQI, the user device 120 may transmit 509 those parameter to the serving BS 110a (note that the IRS configuration pair is a necessary parameter to be signaled, while gain factor and CQI are optional).

If multiple IRS configuration pairs have been provided, the serving BS 110a selects 510 the one most suited, taking into account also configuration requests from other user devices as well as potential system constraints. The IRS 130 may be then configured 511 by the serving BS 110a for the data transmission to the user device 120 according to the selected IRS configuration pair. For the data transmission 513, the data rate can be adapted according to the improved CQI, such that the overall spectral efficiency can be considerably increased. The crucial parameters for configuring the IRS 130 may be contained in the IRS configuration pair, constituted of the reflection beam and the corresponding phase factor. Since the reflection beams are usually preconfigured, these can easily be referenced by an index, specifying the beam from the set of K beams. Hence, their quantization for the signaling requires log2(K) bits. The phase factor may in general be a continuous value in the range [0, 2p]

However, IRS implementations may usually support only a small set of discrete values for the phase shifts of the antenna elements. Today, typically 4 discrete values are supported only, and hence the phase factor applied to the beam at the IRS is constrained by the same restrictions. Therefore, two or only few more bits will be sufficient for quantizing the phase factor to be signaled by the user device.

The optional gain factor may be used to quantify the improvement of the overall signal conditions; it could therefore be expressed in dB-scale and quantized similarly to the CQI values. It is expected, though, that the full range of dB values provided for the CQI quantization is not needed to be considered for the gain factor, since very low gains (e.g. below 1 dB) are not of interest, and the maximum gain attainable by appropriate beam combination may be strictly limited, say: a gain larger 7 dB will be very unlikely.

Hence, very few bits (2-3 bits) may be sufficient for quantizing the gain factor, in particular since this factor will be used mainly for comparing with other user devices that are competing for support of the IRS for their transmission, rather than for choosing another fine granular measure like the modulation and coding scheme (MCS), as being considered for the CQI values.

Fig. 6 shows a schematic diagram illustrating a method 600 for transmitting interference cancellation information to a serving node.

The method 600 comprises: determining 601, by a user device 120, 801a, at least one intelligent reflecting surface, IRS, configuration pair of beam and corresponding phase factor, wherein the IRS configuration pair indicates the beam to be formed at the IRS which reflects a signal from a serving and/or from an interfering node, and the phase factor to be applied to the beam formed at the IRS, e.g. as described above with respect to Figures 1 to 5; and transmitting 602, by the user device 120, 801a, interference cancellation information to the serving node 110a, 820, wherein the interference cancellation information comprises the at least one IRS configuration pair of beam and corresponding phase factor, e.g. as described above with respect to Figures 1 to 5. Fig. 7 shows a schematic diagram illustrating a method 700 for instructing an IRS by a serving node to form a beam.

The method 700 comprises: receiving 701, by a serving node 110, 820, interference cancellation information from a user device 120, 801a, wherein the interference cancellation information comprises at least one IRS configuration pair of beam and corresponding phase factor, wherein the IRS configuration pair of beam and corresponding phase factor indicates a beam to be formed at the IRS which reflects a signal from the serving node 110a, 820 and/or from an interfering node 110b, and a phase factor to be applied to the beam formed at the IRS, e.g. as described above with respect to Figures 1 to 5; and signaling 702, by the serving node 110a, 820, an instruction message to the IRS, the instruction message instructing the IRS to form a beam according to the at least one IRS configuration pair of beam and corresponding phase factor, e.g. as described above with respect to Figures 1 to 5.

Fig. 8 shows a schematic diagram illustrating a communication system.

The communication system 800 includes a user device 801a or user device, respectively, according to an embodiment, an IRS 820a and a serving node or base station 820.

The communication system 800 may further include a plurality of neighboring user devices of the user device 801a that are not shown in Figure 8. The communication system 800 may further include one or more interfering nodes 110b or interfering base stations that are not shown in Figure 8.

In the embodiment shown in Figure 8, the user device 801a is, by way of example, a portable device, in particular a smartphones 801a. In another embodiment, the user device 801a may be, by way of example, a laptop computer.

The user device 801a may be configured to communicate with the base station 820, for instance, via Uu channel. The base station 820 can use a second network device, e.g. implemented as IRS 820a as described above, to enable communication to the user device 801a. The user device 801a may also be configured to communicate with neighboring user devices by sidelink channel without the base station 820 (this communication is not shown in Figure 8). As can be taken from figure 8, the user device 801a may comprise a processing circuitry 803a for instance, a processor 803a, for processing and generating data, a transceiver 805a, including, for instance, a transmitter, a receiver and an antenna, for exchanging data with the other components of the communication system 800, and a non-transitory memory 807a for storing data.

The processor 803a of the user device 801a may be implemented in hardware and/or software. The hardware may comprise digital circuitry, or both analog and digital circuitry. Digital circuitry may comprise components such as application-specific integrated circuits (ASICs), field- programmable arrays (FPGAs), digital signal processors (DSPs), or general-purpose processors.

The non-transitory memory 807a may store data as well as executable program code which, when executed by the processor 803a, causes the user device 801a to perform the functions, operations and methods described in this disclosure.

Likewise, as illustrated in figure 8, the base station 820 may comprise a processor 813 for processing and generating data, a transceiver 815 (or communication interface) for exchanging data with the other components of the communication system 800 as well as a non-transitory memory 817 for storing data.

As described above, the processor 803a of the user device 801a may be configured to: determine at least one intelligent reflecting surface, IRS, configuration pair of beam and corresponding phase factor, wherein the IRS configuration pair indicates the beam to be formed at the IRS 130 which reflects a signal from a serving and/or from an interfering node, and the phase factor to be applied to the beam formed at the IRS 130. The communication interface 805a of the user device 801a may be configured to transmit interference cancellation information to the serving node 820, wherein the interference cancellation information comprises the at least one IRS configuration pair of beam and corresponding phase factor.

As described above, the communication interface 815 of the serving node 820 may be configured to receive interference cancellation information from the user device 801a, wherein the interference cancellation information comprises at least one intelligent reflecting surface, IRS, configuration pair of beam and corresponding phase factor, wherein the IRS configuration pair of beam and corresponding phase factor indicates a beam to be formed at the IRS 130 which reflects a signal from the serving node 110a, 820 and/or from an interfering node 110b, and a phase factor to be applied to the beam formed at the IRS. The processor 813 of the serving node 820 may be configured to signal an instruction message to the IRS, the instruction message instructing the IRS to form a beam according to the at least one IRS configuration pair of beam and corresponding phase factor.

The present disclosure also supports a computer program product including computer executable code or computer executable instructions that, when executed, causes at least one computer to execute the performing and computing steps described herein, in particular the methods and procedures described above. Such a computer program product may include a readable non-transitory storage medium storing program code thereon for use by a computer. The program code may perform the processing and computing steps described herein, in particular the methods and procedures described above.

The solution presented in this disclosure may be applied for industrial loT communication, the required signaling can be defined in corresponding standard documents.

While a particular feature or aspect of the disclosure may have been disclosed with respect to only one of several implementations, such feature or aspect may be combined with one or more other features or aspects of the other implementations as may be desired and advantageous for any given or particular application. Furthermore, to the extent that the terms "include", "have", "with", or other variants thereof are used in either the detailed description or the claims, such terms are intended to be inclusive in a manner similar to the term "comprise". Also, the terms "exemplary", "for example" and "e.g." are merely meant as an example, rather than the best or optimal. The terms “coupled” and “connected”, along with derivatives may have been used. It should be understood that these terms may have been used to indicate that two elements cooperate or interact with each other regardless whether they are in direct physical or electrical contact, or they are not in direct contact with each other.

Although specific aspects have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific aspects shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific aspects discussed herein.

Although the elements in the following claims are recited in a particular sequence with corresponding labeling, unless the claim recitations otherwise imply a particular sequence for implementing some or all of those elements, those elements are not necessarily intended to be limited to being implemented in that particular sequence. Many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the above teachings. Of course, those skilled in the art readily recognize that there are numerous applications of the invention beyond those described herein. While the present invention has been described with reference to one or more particular embodiments, those skilled in the art recognize that many changes may be made thereto without departing from the scope of the present invention. It is therefore to be understood that within the scope of the appended claims and their equivalents, the invention may be practiced otherwise than as specifically described herein.

Claims

CLAIMS:

1. A user device (120, 801a), comprising: a processor (803a), configured to: determine at least one intelligent reflecting surface, IRS, configuration pair of beam and corresponding phase factor, wherein the IRS configuration pair indicates the beam to be formed at the IRS (130) which reflects a signal from a serving and/or from an interfering node, and the phase factor to be applied to the beam formed at the IRS (130); a communication interface (805a) configured to transmit interference cancellation information to the serving node (110a, 820), wherein the interference cancellation information comprises the at least one IRS configuration pair of beam and corresponding phase factor.

2. The user device (120, 801a) of claim 1, wherein the interference cancellation information further comprises at least one of: a gain factor p, a channel quality indicator, CQI, of a channel shaped by the IRS according to the IRS configuration pair, a beam index of the beam.

3. The user device (120, 801a) of claim 1 or 2, wherein the phase factor is selected from a set of discrete values, and a range of the discrete values is [0, 2p]

4. The user device (120, 801a) of anyone of previous claims, wherein the communication interface (805a) is configured to receive a response of interference cancellation information.

5. The user device (120, 801a) of anyone of the previous claims, wherein determining the at least one IRS configuration pair of beam and corresponding phase factor is based on a channel coefficient (b_n) of a serving beam of the serving node (110a, 820) directed towards the user device (120, 801a) and/or a channel coefficient (b,) of an interfering beam of the interfering node (110b) covering the user device (120, 801a).

6. The user device (120, 801a) of any of the preceding claims, wherein determining the at least one IRS configuration pair of beam and corresponding phase factor is based on channel coefficients (b_x,n) of a number of reflection beams (x) formed at the IRS (130) and fed by the serving beam, and/or channel coefficients (b_x,i) of the number of reflection beams (x) fed by the interfering beam.

7. The user device (120, 801a) of claim 6, wherein determining the at least one IRS configuration pair of beam and corresponding phase factor is based on a target metric calculated from the determined channel coefficients (b_n, b_x,n) of the serving beam and the number of reflection beams fed by the serving beam and/or the determined channel coefficients (b,, b_x ) of the interfering beam and the number of reflection beams fed by the interfering beam.

8. The user device (120, 801a) of claim 7, wherein the at least one IRS configuration pair of beam and corresponding phase factor are maximizing the target metric.

9. The user device (120, 801a) of claim 7 or 8, wherein the target metric comprises a signal-to-interference and noise ratio based on the determined channel coefficients (b_n, b_x,n) of the serving beam and the number of reflection beams fed by the serving beam and/or the determined channel coefficients (b,, b_x ) of the interfering beam and the number of reflection beams fed by the interfering beam.

10. The user device (120, 801a) of any of the preceding claims, wherein the user device (120, 801a) is configured with a threshold, and the user device (120, 801a) is triggered to send the IRS configuration pair based on the threshold.

11. The user device (120, 801a) of any of claims 7 to 10, wherein the target metric is based on a signal power of the channel coefficient (b_n) of the serving beam and a number of channel coefficients (b_x,n) of the reflection beams (x) fed by the serving beam, each reflection beam being phase shifted by a respective phase-factor of a predetermined set of phase factors; and/or wherein the target metric is further based on an interference power of the channel coefficient (b,) of the interfering beam and a number of channel coefficients (b_x ) of the reflection beams (x) fed by the interfering beam, each reflection beam being phase shifted by the respective phase-factor of the predetermined set of phase factors.

12. The user device (120, 801a) of any of claims 7 to 11 , wherein the number of reflection beams (x) fed by the serving beam and the number of reflection beams (x) fed by the interfering beam are received from the IRS within a number of successive time slots, each reflection beam (x) fed by the serving beam and each reflection beam (x) fed by the interfering beam obtained within a respective time slot of the number of successive time slots.

13. A serving node (110a, 820) for serving a user device (120, 801a), the serving node (110a, 820) comprising: a communication interface (815), configured to receive interference cancellation information from the user device (120, 801a), wherein the interference cancellation information comprises at least one intelligent reflecting surface, IRS, configuration pair of beam and corresponding phase factor, wherein the IRS configuration pair of beam and corresponding phase factor indicates a beam to be formed at the IRS (130) which reflects a signal from the serving node (110a, 820) and/or from an interfering node (110b), and a phase factor to be applied to the beam formed at the IRS; and a processor (813) configured to signal an instruction message to the IRS, the instruction message instructing the IRS to form a beam according to the at least one IRS configuration pair of beam and corresponding phase factor.

14. The serving node (110a, 820) of claim 13, wherein the interference cancellation information further comprises at least one of: a gain factor p, a channel quality indicator, CQI, of a channel shaped by the IRS according to the IRS configuration pair, a beam index of the beam, at least one other pair of beam and corresponding phase factor.

15. The serving node (110a, 820) of claim 13 or 14, wherein the phase factor is selected from a set of discrete values, and a range of the discrete values is [0, 2p]

16. The serving node (110a, 820) of any of claims 13 to 15, wherein the communication interface (815) is configured to transmit a response of interference cancellation information to the user device (120, 801a).

17. The serving node (110a, 820) of any of claims 13 to 16, wherein the at least one IRS configuration pair of beam and corresponding phase factor is used to maximize a target metric at the user device.

18. The serving node (110a, 820) of claim 17, wherein the target metric comprises a signal-to-interference and noise ratio based on channel coefficients (b_n, b_x,n) of a serving beam of the serving node (110a, 820) directed towards the user device (120, 801a) and a number of reflection beams formed at the IRS and fed by the serving beam, and / or the channel coefficients (b,, b_x ) of an interfering beam of the interfering node (110b) covering the user device (120, 801a) and the number of reflection beams fed by the interfering beam.

19. The serving node (110a, 820) of claim 18, wherein the processor (813) is configured to instruct the IRS (130) to switch off reflection of the serving beam and the interfering beam in a pre-defined time slot in order to enable the user device (120, 801a) determining the channel coefficient (b_n) of the serving beam and the channel coefficient (b,) of the interfering beam.

20. The serving node (110a, 820) of any of claims 13 to 19, wherein the communication interface (815) is configured to transmit a reference signal to the IRS within each of a number of successive time slots in order to enable the IRS (130) to form a respective reflection beam within each time slot.

21. A method (600) for transmitting interference cancellation information to a serving node (110a, 820), the method comprising: determining (601), by a user device (120, 801a), at least one intelligent reflecting surface, IRS, configuration pair of beam and corresponding phase factor, wherein the IRS configuration pair indicates the beam to be formed at the IRS which reflects a signal from a serving and/or from an interfering node, and the phase factor to be applied to the beam formed at the IRS; and transmitting (602), by the user device (120, 801a), interference cancellation information to the serving node (110a, 820), wherein the interference cancellation information comprises the at least one IRS configuration pair of beam and corresponding phase factor.

22. A method (700) for instructing an intelligent reflecting surface, IRS, to form a beam, the method comprising: receiving (701), by a serving node (110, 820), interference cancellation information from a user device (120, 801a), wherein the interference cancellation information comprises at least one IRS configuration pair of beam and corresponding phase factor, wherein the IRS configuration pair of beam and corresponding phase factor indicates a beam to be formed at the IRS which reflects a signal from the serving node (110a, 820) and/or from an interfering node (110b), and a phase factor to be applied to the beam formed at the IRS; and signaling (702), by the serving node (110a, 820), an instruction message to the IRS, the instruction message instructing the IRS to form a beam according to the at least one IRS configuration pair of beam and corresponding phase factor.

23. A computer program product including computer executable code or computer executable instructions that, when executed, causes at least one computer to execute the method (600, 700) according to claim 21 or 22.

24. A computer readable medium, storing instructions that, when executed by a computer, cause the computer to execute the method (600, 700) according to claim 21 or 22.