Determining a configuration for a reconfigurable intelligent surface based on measurements by mobile devices

Abstract

A system for determining a configuration for a reconfigurable intelligent surface (21), which is able to alter the propagation environment of wireless signals in a controlled manner, is configured to cause the reconfigurable intelligent surface to successively use a plurality of candidate configurations during a plurality of time intervals. Each of the time intervals corresponds to one of the candidate configurations. The system is further configured to cause a set of mobile devices (31-36) to perform measurements on wireless signals transmitted by one or more base stations (11) in the plurality of time intervals and report the measurements, receive measurement reports from the set of mobile devices, determine the configuration of the reconfigurable intelligent surface based on the measurement reports, and cause the reconfigurable intelligent surface to use the determined configuration. The measurement reports comprise results of the measurements.

Description

[0001] DETERMINING A CONFIGURATION FOR A RECONFIGURABLE INTELLIGENT

[0002] SURFACE BASED ON MEASUREMENTS BY MOBILE DEVICES

[0003] FIELD OF THE INVENTION

[0004] The invention relates to a system for determining a configuration for a reconfigurable intelligent surface, the reconfigurable intelligent surface being able to alter the propagation environment of wireless signals in a controlled manner.

[0005] The invention further relates to a method of determining a configuration for a reconfigurable intelligent surface, the reconfigurable intelligent surface being able to alter the propagation environment of wireless signals in a controlled manner.

[0006] The invention also relates to computer program products enabling a computer system to perform such a method.

[0007] BACKGROUND OF THE INVENTION

[0008] Reconfigurable Intelligent Surfaces (RISs), also known as Intelligent Reflecting Surfaces (IRS), are network components that can alter the propagation environment in a controlled way in order to achieve some communication improvements. Wireless signals transmitted by base stations and / or mobile devices are reflected, refracted or absorbed by the RIS in a controlled manner. A RIS may be deployed on the wall of a building, for example. The response of a RIS may be controlled dynamically and / or semi- statically through control signaling.

[0009] Alternatively, the RIS may be self-configurable. For example, the paper ‘MARISA: a self-configuring metasurfaces absorption and reflection solution towards 6G’ by Albanese, F. Devoti, V. Sciancalepore, M. Di Renzo and X. Costa-Perez, published in Proceedings of INFOCOM ‘22, describes a ‘self-managed’ or ‘autonomous’ RIS solution that can be partly used for the ‘association’ procedure between the RIS and the surrounding base stations. This solution relies on the RIS intelligence to search for an optimal codeword in the probing phase i.e. identifying the surrounding base stations or mobile devices as well as orthogonal codeword in the communication phase, and does not rely on a control channel.

[0010] The communication improvements are normally focused on improving the throughput of individual mobile devices or the sum-rate throughput of active mobile devices in a cell. Known systems, such as the one described in the above-mentioned paper, cannot be used to resolve a coverage gap. For example, if a RIS would be deployed on a building wall with the purpose of resolving a coverage gap on a high-frequency carrier, known systems would not be able to determine a RIS configuration such that most or all present mobile devices that experienced low (i.e. unsatisfactory) signal quality, now with the placement of RIS would be able to receive signals on the high-frequency carrier with a sufficiently high (satisfactory) signal quality.

[0011] SUMMARY OF THE INVENTION

[0012] It is a first objective of the invention to provide a system, which is able to determine a configuration for a reconfigurable intelligent surface that improves coverage.

[0013] It is a second objective of the invention to provide a method, which can be used for determining a configuration for a reconfigurable intelligent surface that improves coverage.

[0014] In a first aspect of the invention, a system for determining a configuration for a reconfigurable intelligent surface, the reconfigurable intelligent surface being able to alter the propagation environment of wireless signals in a controlled manner, includes at least one processor configured to cause the reconfigurable intelligent surface to successively use a plurality of candidate configurations during a plurality of time intervals, each of the time intervals corresponding to one of the candidate configurations, cause a set of mobile devices to perform measurements on wireless signals transmitted by one or more base stations in the plurality of time intervals and report the measurements, receive measurement reports from the set of mobile devices, the measurement reports comprising results of the measurements, determine the configuration of the reconfigurable intelligent surface based on the measurement reports, and cause the reconfigurable intelligent surface to use the determined configuration.

[0015] By letting the RIS cycle through a plurality of candidate configurations and by determining the RIS configuration based on measurements by the mobile devices, a RIS configuration may be determined that improves coverage, e.g. increases RSRPs for one or more mobile devices. The determination of the RIS configuration is preferably initiated and conducted automatically upon deployment and activation of the RIS, periodically at RIS ‘reconfiguration’ intervals, upon deployment of another base station in the area, and / or when triggered by the network upon detection of areas with low signal quality. The measurements may be RSRP levels, for example.

[0016] The instructions to the mobile devices may specify how the mobile devices should perform the measurements and / or what to report in the measurement reports. The instructions (e.g. communicated to the mobile device via a lower frequency band) how to perform the measurements may include instructions to listen to a higher frequency band where the coverage gap has been identified. The RIS may be controlled to achieve some improvement in coverage, user throughput, spectral efficiency, energy efficiency, sensing and / or localization accuracy. The RIS may be controlled in line with some coverage or performance-related objective (in)directly imposed by the network operator, for example. The set of mobile devices normally includes active mobile devices and optionally includes idle mobile devices.

[0017] Causing a RIS to use a RIS configuration means that that the RIS is configured such that it is reflecting the incoming signals in a given / configured way. It is expected, from practical deployment point of view, that a given RIS would typically have a finite set of candidate configurations. Consequently, determining the configuration of the reconfigurable intelligent surface based on the measurement reports would typically comprise of selecting one of the finite set of candidate configurations based on the measurement reports.

[0018] For the case when the RIS supports different frequency bands (e.g. 800 MHz, 1800 MHz, 3.5 GHz) and the RIS is capable to be configured with different configurations for each individual frequency carriers in parallel, the RIS may be caused / instructed to successively use a plurality of candidate configurations on a selected frequency carrier in each of the different frequency bands, and possibly use different configurations for different frequency bands in parallel, and the set of mobile devices may be caused / instructed to perform and report measurements on the selected frequency carrier in each of the different frequency bands.

[0019] The wireless signals may comprise reference signals, e.g. Synchronization Signal Block (SSB) signals and / or channel state information reference signals (CSI-RS). Reference signals are also known as pilot signals. Since reference signals are transmitted anyway (e.g. SSB signals are always transmitted, CSI-RSs are transmitted as long as there are active users in the cell) and are transmitted frequently, they can be beneficially used to assess the effect of candidate RIS configurations. The benefit of SSB signals is that SSB signals transmitted by a first base station can easily be received by mobile devices served by a second base station (if the mobile devices are within a certain distance of the first base station) and SSB signals can also be received by idle mobile devices, since SSB signals are always transmitted, regardless of whether there are active users in the cell.

[0020] The at least one processor may be configured to instruct the set of mobile devices to perform further measurements on further wireless signals transmitted by the one or more base stations in one or more further time intervals when the reconfigurable intelligent surface is switched off, the measurement reports further comprising results of the further measurements. These further measurements are reference measurements that enable the effect of a RIS configuration to be assessed and these reference measurements are preferably performed close to the moments that the candidate RIS configurations are cycled through.

[0021] For proper comparison, the same set of devices should preferably perform measurements on the wireless signals and the further wireless signals (i.e. during on and off periods) and the same one or more base stations should transmit the wireless signals and the further wireless signals. For proper comparison, the wireless signals and the further wireless signals should preferably be different parts of the same signals, the different parts being transmitted at different times.

[0022] The one or more further time intervals may comprise multiple further time intervals in between the time intervals and the at least one processor may be configured to cause the reconfigurable intelligent surface to switch off during the multiple further time intervals. In this way, a reference measurement is performed very close to the moment that a candidate RIS configuration is used.

[0023] The at least one processor may be configured to determine from the measurement reports, for each respective (RIS) candidate configuration of the candidate configurations, at least one of a) a first quantity of mobile devices in a spatial area whose performance increased more than a predetermined amount when the reconfigurable intelligent surface used the respective candidate configuration compared to their performance when the reconfigurable intelligent surface was switched off, b) a second quantity of mobile devices in the spatial area whose performance decreased more than the predetermined amount when the reconfigurable intelligent surface used the respective candidate configuration compared to their performance when the reconfigurable intelligent surface was switched off, c) a third quantity of mobile devices in the spatial area whose performance exceeded a threshold when the reconfigurable intelligent surface used the respective candidate configuration and did not exceed the threshold when the reconfigurable intelligent surface was switched off, and d) a fourth quantity of mobile devices in the spatial area whose performance exceeded the threshold when the reconfigurable intelligent surface was switched off and did not exceed the threshold when the reconfigurable intelligent surface used the respective candidate configuration, and determine the configuration of the reconfigurable intelligent surface by selecting one of the candidate configurations based on at least one of the first quantity, the second quantity, the third quantity, and the fourth quantity.

[0024] The first and third quantities represent the quantity of mobile devices whose performance is improved and the second and fourth quantities represent the quantity of mobile devices whose performance is reduced. By using a predetermined amount higher than zero, small performance improvements and reductions may be filtered out. The spatial area may be unlimited or limited, e.g. limited to the area of a coverage gap. Determining a quantity of mobile devices in a limited spatial area normally requires that the mobile devices in this limited spatial area are first identified.

[0025] Whether a performance increases, decreases, exceeds a threshold, or does not exceed a threshold may be determined based on a performance indicator which indicates the performance. A first type of performance indicator indicates a better performance when the performance indicator becomes higher. A second type of performance indicator indicates a better performance when the performance indicator becomes lower. With the second type of performance indicator, the performance may exceed the (performance) threshold when the performance indicator stays below an indicator threshold and the performance may stay below the (performance) threshold when the performance indicator exceeds the indicator threshold.

[0026] If a mobile device is capable or might be capable of reporting multiple performance indicators, the instruction to the mobile device may specify which one or more performance indicators to report. If a mobile device determines itself whether the performance increased or decreased more than the predetermined amount, then the instruction to the mobile device may specify the predetermined amount. If a mobile device determines itself whether the performance exceeded the threshold, then the instruction to the mobile device may specify the threshold.

[0027] The at least one processor may be configured to determine a score for each respective candidate configuration of the candidate configurations by applying weights to multiple quantities and adding the multiple weighted quantities, the multiple quantities comprising at least two of the first quantity, the second quantity, the third quantity, and the fourth quantity, and selecting the candidate configuration with the best score from the candidate configurations. Which quantities are to be used and / or which weights are to be used may be specified in an operator policy. An operator policy may be defined, for example, so as to select a RIS configuration that ensures coverage for the largest quantity of mobile devices or so as to select a RIS configuration that does not reduce the performance of mobile devices outside a coverage gap.

[0028] The performance of a respective mobile device of the set of mobile devices for a respective candidate configuration of the candidate configurations may be represented by the best performance indicator of multiple performance indicators of the respective mobile device, each of the multiple performance indicators being determined based on a measurement performed on a different wireless signal of the wireless signals. For example, if SSB signals are used, the best performance indicator would typically be determined based on a measurement performed on an SSB signal that the mobile device would report as best SSB signal during normal operation, and would therefore represent the performance during normal operation most accurately.

[0029] The performance of a respective mobile device of the set of mobile devices for a respective candidate configuration of the candidate configurations may be determined based on the received power and / or the received quality of at least one of the wireless signals. The performance may be indicated by the received power (e.g. RSRP) or the received quality (e.g. RSRQ) of at least one of the wireless signals, for example. The higher the received power and / or received quality, the better the coverage, user throughput, spectral efficiency, energy efficiency, and localization accuracy. The performance may be determined based on multiple performance indicators and / or based on a composite performance indicator which is a combination of multiple performance indicators.

[0030] Each of the (RIS) candidate configurations may comprise a different phase vector, each phase vector prescribing the phase shift applied to the wireless signals as received from the one or more base stations at each of the elements of the reconfigurable intelligent surface in a corresponding time interval of the plurality of time intervals. The phase vector is typically the most important or only component of the configuration of a RIS. The phase vector preferably prescribes the phase shift applied to any signal received at each of the elements of the reconfigurable intelligent surface in the corresponding time interval or to any signal received at each of the elements in the corresponding time interval on a certain carrier frequency.

[0031] The at least one processor may be configured to determine a target area in which an estimated or measured performance does not exceed a threshold, select the one or more base stations based on the spatial area, and cause the set of mobile devices to perform measurements on the wireless signals by instructing each respective base station of the one or more base stations to transmit an instruction message to one or more mobile devices covered by the respective base station. This may be used to cause the most relevant mobile devices to perform measurements. The at least one processor may be configured to determine the target area by determining a coverage gap, for example. For example, the at least one processor may be configured to determine the target area by determining a coverage gap on a high-frequency carrier, for example.

[0032] Coverage gaps may be used as driver for the RIS configuration. The presence of a coverage gap may be identified by using a radio network planning tool or may be determined based on reports from mobile devices, conveyed, for example, via a low- frequency carrier or via the same high-frequency carrier at some instance (location) where the mobile devices do have high-frequency coverage. The at least one processor may also be configured to determine the candidate configurations to be successively used by the reconfigurable intelligent surface based on the target area, for example.

[0033] The at least one processor may be configured to instruct each respective base station of the one or more base stations to broadcast the instruction message and / or transmit the instruction message individually to one or more mobile devices served by the respective base station. The broadcast message may be used to cause idle mobile devices, and optionally active mobile devices, to perform measurements. The individual instruction messages may be used to cause active mobile devices to perform measurements.

[0034] The individual instruction messages may be transmitted to only mobile devices in the target area, and optionally near the target area. The instruction message broadcast by one or more of the base station(s) may specify the target area and the mobile devices may be configured to only perform and report the measurements if they are located in the target area. The instruction message broadcast by one or more of the base station(s) may include a filtering mechanism, e.g. a coin flip probability, which may be used by the mobile devices to determine whether to perform and report the measurements or not. This may be used to avoid that too many mobile devices perform and report measurements.

[0035] In a second aspect of the invention, a mobile device includes at least one processor configured to receive an instruction message from a base station, the instruction message comprising a schedule determined by the system, the schedule specifying a plurality of time intervals in which the mobile device is instructed to perform measurements on wireless signals transmitted by one or more base stations via one or more beams, and an index for each of the plurality of time intervals, perform the measurements on the wireless signals in the plurality of time intervals, create at least one measurement report, the at least one measurement report comprising results of the measurements, the results being determined by averaging a plurality of measured values per combination of beam and index, the plurality of measured values being measured in a time interval associated with the index, or the results enabling the system to average the plurality of measured values per combination of beam and index, and transmit the at least one measurement report to the base station or a different base station for use by the system.

[0036] The results may comprise a subset (e.g. one) of the indices selected based on the averages, or an average value per index selected based on the averages, for example. The one or more beams may be reference beams, e.g. SSB beams, identified with beam IDs, for example. The mobile device may enable the system to average the plurality of measured values per combination of beam and index by including the plurality of measured values in the results and indicating the combination of beam and index for each of the plurality of measured values. A first wireless signal may be transmitted over a beam at a first moment and a second wireless signal may be transmitted over the same beam (having the same beam characteristics) at a second moment. If the measurements performed on these two wireless signals relate to the same index, e.g. are performed in the same time interval or are performed in different time intervals with the same index, then they are grouped in the same measurement set to be (statistically) averaged by the mobile device or by the system.

[0037] The indices may correspond to candidate RIS configurations. In this case, the mobile device needs to statistically process measurements from the same index and need not be aware of the actual RIS configuration corresponding to the particular index. If the OFF configuration is not a candidate configuration, then an index not associated with a candidate configuration may be associated with the OFF configuration. The least one measurement report may be very limited (e.g. best RSRP among the measured time intervals) or extensive (e.g. RSRP measured for each time interval), for example.

[0038] In a third aspect of the invention, a reconfigurable intelligent surface able to alter the propagation environment of wireless signals in a controlled manner includes at least one processor configured to receive a configuration message from the system or from another system, the configuration message comprising a schedule determined by the system and indicating a plurality of candidate configurations, the schedule specifying a plurality of time intervals in which the reconfigurable intelligent surface is instructed to successively use the plurality of candidate configurations, each of the time intervals corresponding to one of the candidate configurations, and successively use the plurality of candidate configurations during the plurality of time intervals. The OFF configuration may be included in or excluded from the plurality of candidate configurations. If the OFF configuration is excluded from the plurality of candidate configurations, the schedule may still specify one or more time intervals in which the reconfigurable intelligent surface is instructed to use the OFF configuration, e.g. to allow reference measurements to be performed.

[0039] In a fourth aspect of the invention, a method of determining a configuration for a reconfigurable intelligent surface, the reconfigurable intelligent surface being able to alter the propagation environment of wireless signals in a controlled manner, includes causing the reconfigurable intelligent surface to successively use a plurality of candidate configurations during a plurality of time intervals, each of the time intervals corresponding to one of the candidate configurations, causing a set of mobile devices to perform measurements on wireless signals transmitted by one or more base stations in the plurality of time intervals and report the measurements, receiving measurement reports from the set of mobile devices, the measurement reports comprising results of the measurements, determining the configuration of the reconfigurable intelligent surface based on the measurement reports, and causing the reconfigurable intelligent surface to use the determined configuration. The method may be performed by software running on a programmable device. This software may be provided as a computer program product.

[0040] In a fifth aspect of the invention, a method of performing measurements at a mobile device includes receiving an instruction message from a base station at the mobile device, the instruction message comprising a schedule determined by the system, the schedule specifying a plurality of time intervals in which the mobile device is instructed to perform measurements on wireless signals transmitted by one or more base stations via one or more beams, and an index for each of the plurality of time intervals, performing the measurements on the wireless signals in the plurality of time intervals, creating at least one measurement report, the at least one measurement report comprising results of the measurements, the results being determined by averaging a plurality of measured values per combination of beam and index, the plurality of measured values being measured in a time interval associated with the index, or the results enabling the system to average the plurality of measured values per combination of beam and index, and transmitting the at least one measurement report to the base station or a different base station for use by the system.

[0041] The method may be performed by software running on a programmable device. This software may be provided as a computer program product. As mentioned above, the instructions to the mobile devices, i.e. the instruction messages, may specify how the mobile devices should perform the measurements (e.g. what metric and under what circumstances) and / or what to report to in the measurement reports (e.g. in what format).

[0042] In a sixth aspect of the invention, a method of configuring a reconfigurable intelligent surface, the reconfigurable intelligent surface being able to alter the propagation environment of wireless signals in a controlled manner, includes receiving a configuration message from the system or from another system, the configuration message comprising a schedule determined by the system and indicating a plurality of candidate configurations, the schedule specifying a plurality of time intervals in which the reconfigurable intelligent surface is instructed to successively use the plurality of candidate configurations, each of the time intervals corresponding to one of the candidate configurations, and successively using the plurality of candidate configurations during the plurality of time intervals. The method may be performed by software running on a programmable device. This software may be provided as a computer program product.

[0043] Moreover, a computer program for carrying out the methods described herein, as well as a non-transitory computer readable storage-medium storing the computer program are provided. A computer program may, for example, be downloaded by or uploaded to an existing device or be stored upon manufacturing of these systems. A non-transitory computer-readable storage medium stores at least a first software code portion, the first software code portion, when executed or processed by a computer, being configured to perform executable operations for determining a configuration for a reconfigurable intelligent surface, the reconfigurable intelligent surface being able to alter the propagation environment of wireless signals in a controlled manner.

[0044] The executable operations include causing the reconfigurable intelligent surface to successively use a plurality of candidate configurations during a plurality of time intervals, each of the time intervals corresponding to one of the candidate configurations, causing a set of mobile devices to perform measurements on wireless signals transmitted by one or more base stations in the plurality of time intervals and report the measurements, receiving measurement reports from the set of mobile devices, the measurement reports comprising results of the measurements, determining the configuration of the reconfigurable intelligent surface based on the measurement reports, and causing the reconfigurable intelligent surface to use the determined configuration.

[0045] A non-transitory computer-readable storage medium stores at least a second software code portion, the second software code portion, when executed or processed by a computer, being configured to perform executable operations for performing measurements at a mobile device.

[0046] The executable operations include receiving an instruction message from a base station at the mobile device, the instruction message comprising a schedule determined by the system, the schedule specifying a plurality of time intervals in which the mobile device is instructed to perform measurements on wireless signals transmitted by one or more base stations via one or more beams, and an index for each of the plurality of time intervals, performing the measurements on the wireless signals in the plurality of time intervals, creating at least one measurement report, the at least one measurement report comprising results of the measurements, the results being determined by averaging a plurality of measured values per combination of beam and index, the plurality of measured values being measured in a time interval associated with the index, or the results enabling the system to average the plurality of measured values per combination of beam and index, and transmitting the at least one measurement report to the base station or a different base station for use by the system.

[0047] A non-transitory computer-readable storage medium stores at least a third software code portion, the third software code portion, when executed or processed by a computer, being configured to perform executable operations for configuring a reconfigurable intelligent surface, the reconfigurable intelligent surface being able to alter the propagation environment of wireless signals in a controlled manner. The executable operations include receiving a configuration message from the system or from another system, the configuration message comprising a schedule determined by the system and indicating a plurality of candidate configurations, the schedule specifying a plurality of time intervals in which the reconfigurable intelligent surface is instructed to successively use the plurality of candidate configurations, each of the time intervals corresponding to one of the candidate configurations, and successively using the plurality of candidate configurations during the plurality of time intervals.

[0048] As will be appreciated by one skilled in the art, aspects of the present invention may be embodied as a device, a method or a computer program product. Accordingly, aspects of the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a "circuit", "module" or "system." Functions described in this disclosure may be implemented as an algorithm executed by a processor / microprocessor of a computer. Furthermore, aspects of the present invention may take the form of a computer program product embodied in one or more computer readable medium(s) having computer readable program code embodied, e.g., stored, thereon.

[0049] Any combination of one or more computer readable medium(s) may be utilized. The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of a computer readable storage medium may include, but are not limited to, the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of the present invention, a computer readable storage medium may be any tangible medium that can contain, or store, a program for use by or in connection with an instruction execution system, apparatus, or device.

[0050] A computer readable signal medium may include a propagated data signal with computer readable program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated signal may take any of a variety of forms, including, but not limited to, electro-magnetic, optical, or any suitable combination thereof. A computer readable signal medium may be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device.

[0051] Program code embodied on a computer readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber, cable, RF, etc., or any suitable combination of the foregoing. Computer program code for carrying out operations for aspects of the present invention may be written in any combination of one or more programming languages, including an object oriented programming language such as Java(TM), Smalltalk, C++ or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer, or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider).

[0052] Aspects of the present invention are described below with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor, in particular a microprocessor or a central processing unit (CPU), of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer, other programmable data processing apparatus, or other devices create means for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0053] These computer program instructions may also be stored in a computer readable medium that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the computer readable medium produce an article of manufacture including instructions which implement the fimction / act specified in the flowchart and / or block diagram block or blocks.

[0054] The computer program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0055] The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of devices, methods and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s).

[0056] It should also be noted that, in some alternative implementations, the functions noted in the blocks may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and / or flowchart illustrations, and combinations of blocks in the block diagrams and / or flowchart illustrations, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

[0057] BRIEF DESCRIPTION OF THE DRAWINGS

[0058] These and other aspects of the invention are apparent from and will be further elucidated, by way of example, with reference to the drawings, in which:

[0059] Fig. 1 shows an example of a coverage gap;

[0060] Fig. 2 is a block diagram of an embodiment of the system, of an embodiment of the RIS, and of embodiments of the mobile devices;

[0061] Fig. 3 is a flow diagram of a first embodiment of the method of determining a configuration for a reconfigurable intelligent surface;

[0062] Fig. 4 is a flow diagram of a second embodiment of the method of determining a configuration for a reconfigurable intelligent surface;

[0063] Fig. 5 illustrates the RIS of Fig. 2 successively using a plurality of candidate configurations;

[0064] Fig. 6 illustrates a first implementation of a RIS configuration search procedure;

[0065] Fig. 7 illustrates a second implementation of a RIS configuration search procedure;

[0066] Fig. 8 shows an example of measurements performed by a mobile device; Fig. 9 is a flow diagram of a third embodiment of the method of determining a configuration for a reconfigurable intelligent surface; and

[0067] Fig. 10 is a block diagram of an exemplary data processing system for performing the methods of the invention.

[0068] Corresponding elements in the drawings are denoted by the same reference numeral.

[0069] DETAILED DESCRIPTION OF THE DRAWINGS

[0070] The methods of the invention may be used to improve coverage, e.g. increase RSRPs. Fig. 1 shows an example in which a RIS 21 is used to resolve a coverage gap 17 on a high-frequency carrier. In other examples, a RIS may be used to resolve a coverage gap on a low-frequency or medium-frequency carrier or may be used to improve coverage without there being a coverage gap. The presence of the coverage gap 17 may be identified with a radio network planning tool or based on reports from mobile devices, conveyed, for example, via a low-frequency carrier or via the same high-frequency carrier (at moments and locations where the mobile devices do have high-frequency coverage).

[0071] When base station 11 transmits the best possible beam on a high frequency carrier either directly or indirectly (reflected via some default object in the environment) towards a mobile device 33, and it does not reach mobile device 33 with sufficient signal strength (in the former case due to the signal attenuation caused by obstacle 15), mobile device 33 is said to be in a coverage gap on the high frequency carrier. In the example of Fig. 1 , the coverage gap 17 only exists on the high frequency carrier, while on a lower frequency carrier the base station 11 is able to transmit a beam 54, which reaches mobile devices 33 and 32 with sufficient signal strength (i.e. sufficiently high RSRP). On the lower frequency, the beam 54 somehow either directly (through the obstacle 15) or indirectly (reflected via some default object in the environment) reaches mobile devices 33 and 32 with sufficient signal strength. This is just an example; other examples are also possible.

[0072] As a result of the obstacle 15, mobile device 33 is in the coverage gap 17 for the high-frequency carrier. Mobile device 32 is also in this high-frequency carrier coverage gap. Mobile devices 31 and 34-36 are not in this coverage gap. By using RIS 21 with a suitable configuration, the base station 11 is able to transmit a beam 51 which is reflected by the reconfigurable intelligent surface 21 such that the mobile device 33 receives reflected beam 52 with sufficiently high RSRP.

[0073] Similarly, the base station 11 is able to transmit another beam (not shown in Fig. 1) which is reflected by the reconfigurable intelligent surface 21 such that the mobile device 32 receives a reflected beam (also not shown in Fig. 1) with sufficiently high RSRP. The RIS 21 may be deployed on a building wall, for example. The RIS 21 may be deployed at some feasible location with the purpose of resolving the coverage gap 17 on the high- frequency carrier, for example.

[0074] However, a configuration of the RIS 21 that works best for mobile device 33 may not work best for mobile device 32. It is possible to adapt the RIS configuration in a highly dynamic manner, e.g. to optimize for specific mobile devices and potentially even ‘follow’ them as they move about. Such dynamic user-specific adaptation of the RIS configuration would be (near) optimal, but may require (many) more measurements and / or (much) more measurement feedback signaling. It may therefore be beneficial to configure the RIS 21 (semi-)statically instead, e.g. based on the feedback from many mobile devices that may be in the area during some period, which may include both mobile device 32 and mobile device 33 in the example of Fig. 1.

[0075] The above-described example with a high-frequency coverage gap is just an example of a network problem driving RIS deployment and configuration. Improving coverage to improve user throughput is another example of a network problem.

[0076] Fig. 2 is a block diagram of a system 1, a RIS 21, and mobile devices 31-33. The system 1 is an embodiment of the system for determining a configuration for a reconfigurable intelligent surface. The RIS 21 is an embodiment of the reconfigurable intelligent surface for use with the system. The reconfigurable intelligent surface is able to alter the propagation environment of wireless signals in a controlled manner. The mobile devices 31-33 are embodiments of the mobile devices for use with the system.

[0077] In the example of Fig. 2, mobile devices 31-33 are served via the base station 11. The system 1 may communicate with the mobile devices 31-33 via the base station 11. The base station 11 may comprise a plurality of distributed units that share a common centralized unit in a Centralized RAN (C-RAN) architecture, for example. In the example of Fig. 2, mobile devices 34-36 of Fig. 1 are not shown. Mobile devices 34-36 of Fig. 1 may be configured in a similar manner as mobile devices 31-33.

[0078] The system 1 comprises a receiver 3, a transmitter 4, a processor 5, and a memory 7. The processor 5 is configured to cause the RIS 21 to successively use a plurality of candidate configurations during a plurality of time intervals. Each of the time intervals corresponds to one of the candidate configurations. The processor 5 is further configured to cause mobile devices 31-33 to perform measurements on wireless signals transmitted by at least base station 11 in the plurality of time intervals and report the measurements, receive measurement reports from the mobile devices 31-33, determine the configuration of the RIS 21 based on the measurement reports, and cause the RIS 21 to use the determined configuration. The measurement reports comprise results of the measurements. Other mobile devices might or might not be instructed to perform the measurements, e.g. mobile devices 34-36 of Fig. 1. The OFF configuration of the RIS 21 may be included in or excluded from the plurality of candidate configurations.

[0079] The RIS 21 comprises a processor / controller 25, a memory 27, and a plurality of discrete elements on the surface of the RIS 21, including elements 211, 212, to 219. The RIS 21 may be, for example, a two-dimensional surface of engineered material whose properties are reconfigurable rather than static. The phase vector to be used may be selected on a per-element or group-of-elements level. The scattering, absorption, reflection, and diffraction properties of the entire RIS 21 may thereby be changed with time.

[0080] The processor 25 may be configured to receive a configuration message from the system 1 or from another system (not shown in Fig. 2), for example. The configuration message comprises a schedule determined by the system 1 and indicates a plurality of candidate configurations. The schedule specifies a plurality of time intervals in which the RIS 21 is instructed to successively use the plurality of candidate configurations. Each of the time intervals corresponds to one of the candidate configurations. The processor 25 is further configured to successively use the plurality of candidate configurations during the plurality of time intervals according to the schedule. To use a candidate configuration, the processor 25 is configured to map the candidate configuration (e.g. the phase vector) to the properties of the elements 211-219.

[0081] The mobile devices 31-33 each comprise a receiver 43, a transmitter 44, a processor 45, and a memory 47. The processor 45 is configured to receive an instruction message from a base station, perform the measurements on the wireless signals in the plurality of time intervals in accordance with the instruction message, create at least one measurement report, and transmit the at least one measurement report to the base station 11 or to a different base station for use by the system 1. The at least one measurement report comprises results of the measurement.

[0082] The instruction message may comprise a schedule determined by the system 1 which specifies the plurality of time intervals in which the mobile device is instructed to perform measurements on wireless signals transmitted by one or more base stations via one or more beams and an index for each of the plurality of time intervals. The processor 45 may be configured to perform the measurements on the wireless signals in the plurality of time intervals according to this schedule.

[0083] In this case, the processor 45 is configured to determine the results by averaging a plurality of measured values per combination of beam and index, which are measured in a time interval associated with the index, or to determine results which enable the system 1 to average the plurality of measured values per combination of beam and index. The results may comprise a subset (e.g. one) of the indices selected based on the averages, or an average value per index selected based on the averages, for example. The one or more beams may be reference beams, e.g. SSB beams, identified with beam IDs, for example. The mobile device may enable the system to average the plurality of measured values per combination of beam and index by including the plurality of measured values in the results and indicating the combination of beam and index for each of the plurality of measured values.

[0084] A first wireless signal may be transmitted over a beam at a first moment and a second wireless signal may be transmitted over the same beam (having the same beam characteristics) at a second moment. If the measurements performed on these two wireless signals relate to the same index, e.g. are performed in the same time interval or are performed in different time intervals with the same index, then they are (statistically) averaged by the mobile device or by the system.

[0085] The indices may correspond to candidate RIS configurations. In this case, the mobile device needs to statistically process measurements from the same index and need not be aware of the actual RIS configuration corresponding to the particular index. If the OFF configuration is not a candidate configuration, then an index not associated with a candidate configuration may be associated with the OFF configuration. The least one measurement report may be very limited (e.g. best RSRP among the measured time intervals) or extensive (e.g. RSRP measured for each time interval), for example.

[0086] In the embodiment shown in Fig. 2, the system 1 comprises one processor. In an alternative embodiment, the system 1 comprises multiple processors. The processor 5 may be a general-purpose processor, e.g., an Intel or an AMD processor, or an applicationspecific processor, for example. The processor 5 may comprise multiple cores, for example. The processor 5 may run a Unix-based or Windows operating system, for example. The memory 7 may comprise solid state memory, e.g., one or more Solid State Disks (SSDs) made out of Flash memory, or one or more hard disks, for example.

[0087] The receiver 3 and the transmitter 4 may use one or more wired or wireless communication technologies to communicate with the base station 11 and the RIS 21. The receiver 3 and the transmitter 4 may use one or more communication technologies (wired or wireless) to communicate with other systems in the radio access network or in the core network, for example. The receiver 3 and the transmitter 4 may be combined in a transceiver. The system 1 may comprise other components typical for a component in a mobile communication network, e.g., a power supply. In the embodiment of Fig. 2, system 1 is a standalone system. In an alternative embodiment, system 1 is co-located with a base station, e.g. base station 11. In the embodiment shown in Fig. 2, the RIS 21 comprises one processor. In an alternative embodiment, the RIS 21 comprise multiple processors. The processor 25 may be a general-purpose processor, e.g., an Intel or an AMD processor, or an applicationspecific processor, for example. The processor 25 may comprise multiple cores, for example. The processor 25 may run a Unix-based or Windows operating system, for example. The memory 27 may comprise solid state memory, for example.

[0088] In the embodiment shown in Fig. 2, the mobile devices 31-33 comprise one processor 45. In an alternative embodiment, one or more of the mobile devices 31-33 comprise multiple processors. The processor 45 may be a general-purpose processor, e.g., an ARM or Qualcomm processor, or an application-specific processor. The processor 45 may run Google Android or Apple iOS as operating system, for example.

[0089] The receiver 43 and the transmitter 44 of the mobile devices 31-33 may use one or more wireless communication technologies such as Wi-Fi, LTE, and / or 5G New Radio to communicate with base stations, for example. The receiver 43 and the transmitter 44 may be combined in a transceiver. The mobile devices 31-33 may comprise other components typical for user equipment, e.g., a battery and / or a power connector.

[0090] A mobile device may also be referred to by those skilled in the art as user equipment (UE), a mobile station (MS), a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a wireless terminal, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal (AT), a mobile terminal, a remote terminal, a handset, a terminal, a user agent, a mobile client, a client, or some other suitable terminology.

[0091] A first embodiment of the method of determining a configuration for a reconfigurable intelligent surface is shown in Fig. 3. The reconfigurable intelligent surface is able to alter the propagation environment of wireless signals in a controlled manner. The method of determining a configuration for a reconfigurable intelligent surface may be performed by the system 1 of Fig. 2, for example.

[0092] A step 101 comprises causing the reconfigurable intelligent surface to successively use a plurality of candidate configurations during a plurality of time intervals. Each of the time intervals corresponds to one of the candidate configurations. Each of the candidate configurations may comprise a different phase vector, for example. Each phase vector prescribes the phase shift applied to any wireless signal received at each of the elements of the reconfigurable intelligent surface in a corresponding time interval of the plurality of time intervals.

[0093] A step 103 comprises causing a set of mobile devices to perform measurements on wireless signals transmitted by one or more base stations in the plurality of time intervals and report the measurements. The set of mobile devices normally include active mobile devices and optionally include idle mobile devices. The measurements may be RSRP levels, for example. The wireless signals may comprise reference signals, e.g. SSB signals.

[0094] A step 105 comprises receiving measurement reports from the set of mobile devices. The measurement reports comprise results of the measurements. A step 107 comprises determining the configuration of the reconfigurable intelligent surface based on the measurement reports received in step 105. A step 109 comprises causing the reconfigurable intelligent surface to use the configuration determined in step 107.

[0095] For example, steps 107 and 109 may include processing collected measurement reports upon termination of the RIS configuration search procedure, and subsequently deriving and enforcing, to the RIS, the selected optimal configuration which is found to best mitigate an identified ‘high-frequency coverage gap’, while having bearable or minimal negative impact on e.g. SSB / CSI-RS signal strengths received by mobile devices outside the area of the high-frequency coverage gap.

[0096] The RIS may be controlled to achieve some improvement in coverage, user throughput, spectral efficiency, energy efficiency, sensing and / or localization accuracy. The RIS may be controlled in line with some coverage or performance-related objective (in)directly imposed by the network operator, for example.

[0097] The method of Fig. 3 is preferably performed automatically upon deployment and activation of the RIS, upon deployment of another base station in the area, periodically at RIS ‘re-configuration’ intervals, and / or when triggered by the network upon detection of areas with low signal quality. The configuration of the RIS may be adjusted after deployment and activation of the RIS, for example on a relatively high time scale of e.g. days, weeks or months.

[0098] For the case when the RIS supports different frequency bands (e.g. 800 MHz, 1800 MHz, 3.5 GHz) and the RIS is capable to be configured with different configurations for each individual frequency carriers in parallel, the RIS may be caused / instructed to successively use a plurality of candidate configurations on a selected frequency carrier in each of the different frequency bands, and possibly use different configurations for different frequency bands in parallel, and the set of mobile devices may be caused / instructed to perform and report measurements on the selected frequency carrier in each of the different frequency bands.

[0099] A second embodiment of the method of determining a configuration for a reconfigurable intelligent surface, a first embodiment of the method of performing measurements at a mobile device, and a first embodiment of the method of configuring the reconfigurable intelligent surface are shown in Fig. 4. The reconfigurable intelligent surface is able to alter the propagation environment of wireless signals in a controlled manner.

[0100] The method of determining a configuration for a reconfigurable intelligent surface may be performed by the system 1 of Fig. 2, for example. The method of performing measurements at a mobile device may be performed by the mobile devices 31-33 of Fig 2, for example. The method of configuring the reconfigurable intelligent surface may be performed by the reconfigurable intelligent surface 21 of Fig. 2, for example.

[0101] A step 100 in Fig. 4 comprises the system determining parameters of the configuration search procedure. Step 100 may include, for example, determining a duration of the RIS configuration search procedure, determining a duration / periodicity of successive ON / OFF periods, determining a predetermined range of RIS configurations, and / or determining the set of mobile devices to be instructed to participate in the configuration search procedure. The RIS configurations may correspond to different reflective directivities, for example. Step 100 is not always required. For example, step 100 may only be needed when configuring the RIS for the first time and the parameters may be stored for reconfiguring the RIS again later.

[0102] Step 101 comprises the system causing, based on the parameters determined in step 100, the reconfigurable intelligent surface to successively use a plurality of candidate configurations during a plurality of time intervals. Each of the time intervals corresponds to one of the candidate configurations. It is assumed that the base stations, mobile devices, and the reconfigurable intelligent surface are time-synchronized with each other. In step 101, the system may instruct the reconfigurable intelligent surface directly or may instruct another system, e.g. a controller of the reconfigurable intelligent surface, to instruct the reconfigurable intelligent surface, for example.

[0103] These candidate configurations correspond to configurations when the reconfigurable intelligent surface is switched on and these time intervals are also referred to as ON periods. Step 101 may further comprise the system causing the reconfigurable intelligent surface to switch off during one or more further time intervals. These further time intervals are also referred to as OFF periods. The reconfigurable intelligent surface being switched off (also referred to as the OFF configuration) may be considered as a further candidate configuration. Alternatively or additionally, measurements performed while the reconfigurable intelligent surface was switched off may be used as a reference for evaluating the measurements performed while the reconfigurable intelligent surface was switched on.

[0104] For example, step 101 may involve instructing the RIS 21 to sweep through different candidate configurations when reflecting high-frequency signals of one or more surrounding base stations with ON and OFF periods. The configuration search procedure may include a single OFF period or multiple OFF periods. If the configuration search procedure includes multiple OFF periods, the multiple OFF periods may be interleaved between the ON periods. The different candidate configurations may be in the form of a phase vector prescribing the phase shift applied to the incoming RF signals, e.g. the incoming RF signals from the surrounding base stations, at each of the RIS elements. For example, the RIS may have N distinct phase vectors corresponding with distinct reflecting angles for the incoming RF signals.

[0105] It is non-trivial what it means for a RIS to be ‘off . It normally does not mean that the RIS is switched off, but that the RIS uses a default configuration. For example, it could mean a RIS configuration in which the RIS absorbs all incoming signals i.e. the RIS reflectivity is switched ‘off . Alternatively, a RIS ‘off configuration could be also the situation in which the RF signal’s reflections are just ‘randomly’ reflected by the RIS, for example.

[0106] The duration / periodicity of successive ON / OFF periods and the duration of the search configuration procedure, Tconfig_period, may be determined in step 100. The following is an example of how these values may be determined. If a network operator has configured seven SSBs for its base stations, the sweeping cycle to transmit all of these seven SSBs may be configured to e.g. 20 milliseconds. If a mobile device needs to receive five SSB transmissions for its RSRP measurement to be sufficiently reliable, this would mean that the mobile device within 5x20 milliseconds = 100 milliseconds can do its RSRP measurement averaging and produce an RSRP value. This would mean that the duration of each of the OFF / ON periods may be configured to 5x20 milliseconds.

[0107] The Tconfig_period depends on the number of different RIS configurations to be successively used and whether the OFF periods are interleaved between the ON periods. Fig. 5 shows N different reflective angle configurations ai to a-. of RIS 21. Reflected beam 84 is the result of using RIS configuration ai on the incoming beam(s) 51 from base station 11, reflected beam 85 is the result of using RIS configuration a2 on the incoming beam(s) 51 from base station 11, reflected beam 88 is the result of using RIS configuration ON-I on the incoming beam(s) 51 from base station 11, and reflected beam 89 is the result of using RIS configuration <XN on the incoming beam(s) 51 from base station 11. The RIS configurations are also used to reflect beams from other devices in the surroundings (not shown in Fig. 5).

[0108] Fig. 6 illustrates a first implementation of a RIS configuration search procedure in which the OFF period occurs once, before the ON periods. In the example of Fig. 6, the Tconfig_period 71 consists of a RIS OFF period 73 with a duration of 5x20 milliseconds followed by N RIS ON periods 74 to 79, where a different RIS configuration is used in each ON period. N is the number of different RIS configurations to be successively used. This number may be determined in step 100. N may depend on how granular the RIS configuration capabilities are. The Tconfig_period may then be calculated as (N+l)x5x20 milliseconds.

[0109] Fig. 7 illustrates a second implementation of a RIS configuration search procedure in which the OFF periods are interleaved between the ON periods. In the example of Fig. 7, the Tconfig_period 91 consists of N OFF periods 73, interleaved between N ON periods 74 to 79. The Tconfig_period may then be calculated as (2xN)x5x20 milliseconds. In the examples of Figs. 6 and 7, the RIS being switched off is not considered to be a configuration, i.e. it is not one of the candidate configurations which may be selected for normal operational use. In an another example, the OFF configuration may be one of the candidate configurations which may be selected for normal operational use.

[0110] When the mobile devices are instructed to perform the measurements in step 103 the instruction may specify the ON and OFF structure of the Tconfig_period (e.g. according to Fig. 6 or Fig. 7), or this ON and OFF structure may be preconfigured in the mobile device, so the mobile device can group the corresponding RSRP measurement samples together, for example belonging to the OFF periods or the specific ON period with a given configuration ON, for statistical processing purposes.

[0111] In the embodiment of Fig. 4, in step 101, the system transmits a configuration message which comprises a schedule determined by the system and indicates the plurality of candidate configurations. The schedule specifies the plurality of time intervals in which the reconfigurable intelligent surface is instructed to successively use the plurality of candidate configurations. The time intervals and the further time interval(s) are aligned and synchronized with the mobile devices. For example, the ON / OFF durations and the number of configurations N may be communicated by the system to both the RIS and the mobile devices.

[0112] A step 121 comprises the reconfigurable intelligent surface receiving the configuration message from the system or from the other system. In an alternative embodiment, the reconfigurable intelligent surface does not receive a schedule but is instructed by the system or by the other system to use one of the plurality of candidate configurations just before it needs to use this candidate configuration. The reconfigurable intelligent surface does not need to be aware that it is successively using the plurality of candidate configurations.

[0113] Step 103 comprises the system causing, based on the parameters determined in step 100, a set of mobile devices to perform measurements on wireless signals transmitted by one or more base stations in the plurality of time intervals via one or more beams and report the measurements. If a schedule is transmitted to the mobile devices and the mobile device are not able to determine a start time and an end time of the procedure from this schedule, this start time and / or this end time may be specified separately in the instruction message transmitted to the mobile devices.

[0114] In the embodiment of Fig. 4, step 103 comprises instructing one or more base stations to instruct the set of mobile devices to perform the measurements. For example, the mobile devices may be instructed to listen and report the high-frequency signal level while the RIS is busy with the RIS configuration search procedure, and this instruction may be transmitted provided via a broadcast message or via unicast signaling messages. Although Fig. 4 shows step 101 being performed before step 103, step 101 may also be performed after step 103 or these steps may be performed in parallel.

[0115] Step 103 may include causing the set of mobile devices to perform further measurements on further wireless signals transmitted by the one or more base stations in one or more further time intervals when the reconfigurable intelligent surface is switched off. The measurement reports further comprise results of the further measurements. These one or more further time intervals (OFF periods) have been described above in more detail.

[0116] For proper comparison, the same set of devices should preferably perform measurements on the wireless signals and the further wireless signals (i.e. during on and off periods) and the same one or more base stations should transmit the wireless signals and the further wireless signals. For proper comparison, the wireless signals and the further wireless signals should preferably be different parts of the same signals, the different parts being transmitted at different times.

[0117] As described in relation to Fig. 7, multiple further time intervals may be positioned / interleaved between the time intervals. In this case, step 101 includes causing the reconfigurable intelligent surface to switch off during the multiple further time intervals. The length of the OFF and ON time intervals for the RIS (including interleaved or not) and the N number of different configurations may be provided to the mobile devices (via control signaling) to allow the mobile devices to calculate the corresponding RSRP values for the OFF period(s) and individual ON periods.

[0118] The instructions to the mobile devices may specify how the mobile devices should perform the measurements and / or what to report in the measurement reports. The instructions (e.g. communicated to the mobile device via a carrier in a lower frequency band) how to perform the measurements may include instructions to listen to a carrier in a higher frequency band.

[0119] The instructions what to report in the measurement reports may include what to report (e.g. the RSRPs of the received SSB and / or CSI-RS signals on the high-frequency carrier), the format of the measurement reports, and / or how / when to submit the measurement reports. For example, the mobile devices may be instructed to submit measurement reports:

[0120] ■ When a mobile device experiences no high-frequency coverage without the RIS (i.e. RIS is OFF) but does experience high-frequency coverage with the RIS under a particular RIS configuration setting.

[0121] ■ When a mobile device experiences a substantial coverage change (|ARSRP| > X dB), where this change can be an improvement (i.e. increased RSRP) or a deterioration (i.e. decreased RSRP) under a particular RIS configuration setting and relative to when the RIS is OFF and / or relative when compared to the last reported situation with RIS ON.

[0122] The instructions may specify whether the mobile device should provide minimum reporting or elaborate reporting. This is illustrated with the help of an example. As shown in Fig. 8, a certain mobile device is able to measure two cells, Cell A (labelled 201) and Cell B (labelled 203), each configured with 7 SSBs labelled as Al to A7 and Bl to B7, respectively. The mobile device is able to measure part of the SSBs and concludes that:

[0123] • During the RIS OFF period, the strongest measured RSRP is from SSB A2 from Cell A (RSRPA2).

[0124] • During the RIS ON periods with configurations ai.. QN-I, the strongest measured RSRP is from SSB A3 from Cell A (RSRPA3).

[0125] • During the RIS ON period with configuration <XN (i.e. the last RIS ON configuration), the strongest RSRP is from SSB Bl from Cell B (RSRPB1).

[0126] • Overall, among all the measured RSRP values, the strongest measured RSRP value is from SSB A3 from Cell A (RSRP A3), when the RIS had an ON period with configuration a2.

[0127] Minimum reporting might involve only reporting the mobile device ‘s favorite / preferred configuration. In this example, that would be a2, the configuration with the strongest measured RSRP value, i.e. RSRPA3. Elaborate reporting might involve reporting the measured RSRP value per period / candidate configuration, i.e. for the individual OFF period and individual ON periods: (OFF, RSRPA2); (ONal, RSRPA3); (ONa2, RSRPA3); ...(ONaN, RSRPB1). ONai denotes the index corresponding to ON configuration a,.

[0128] The elaborate reporting may be reduced by reporting the RSRP value during the OFF period and only reporting ON periods having a RSRP value falling outside X dB range of the measured RSRP value during the OFF period e.g. if the absolute RSRP change |ARSRP| > X dB. In this way, having e.g. X = 0.5 dB would filter out ON periods with insignificant increase / decrease of the RSRP value that are not worthwhile to report. The measurement instructions may specify certain SSB IDs and instruct the mobile devices to only listen for and report on SSB signals with these SSB IDs.

[0129] In the embodiment of Fig. 4, the system transmits an instruction message which comprises the schedule determined by the system. The schedule specifies the plurality of time intervals in which the mobile device is instructed to perform measurements on wireless signals transmitted by one or more base stations. The instruction message further comprises an index for each of the plurality of time intervals (e.g. ONai). A step 111 comprises the mobile device(s) receiving this instruction message from a base station. In an alternative embodiment, the mobile device(s) do not receive a schedule but are instructed to start performing measurements just before a time interval starts.

[0130] A step 123 comprises the reconfigurable intelligent surface successively using the plurality of candidate configurations during the plurality of time intervals according to the schedule received in step 121. Fig. 5 illustrates RIS 21 of Fig. 2 successively using a plurality of candidate configurations ai to QIN. In the example of Fig. 5, N configurations are successively used on the incoming beam 51, of which only the reflected beams of four configurations are represented by arrows: beam 84 (configuration ai), beam 85 (configuration 0C2), beam 88 (configuration OCN-I), and beam 89 (configuration QIN).

[0131] These beams 84-89 are distinct reflections of a reference signal, e.g. SSB signal, transmitted by the base station 11 and reflected by the RIS 21. Although not shown in Fig. 5, these different configurations (ai... OCN) will impact the reflections on all incoming beams to RIS 21 from base station 11 (or other base stations in surroundings). This is not shown in Fig. 5 for the sake of simplicity.

[0132] A step 113 comprises the mobile device(s) performing the measurements on the wireless signals in the plurality of time intervals according to the instructions and schedule received in step 111. A step 115 comprises the mobile device(s) creating at least one measurement report, e.g. as described in relation to step 103. The at least one measurement report comprises results of the measurements. The results are determined by averaging a plurality of measured values per combination of beam and index, which are measured in a time interval associated with the index, or the results enable the system to average the plurality of measured values per combination of beam and index.

[0133] As described in relation to step 103, the results may comprise a subset (e.g. one) of the indices selected based on the averages, or an average value per index selected based on the averages, for example. The one or more beams may be reference beams, e.g. SSB beams, identified with beam IDs, for example. The mobile device(s) may enable the system to average the plurality of measured values per combination of beam and index by including the plurality of measured values in the results and indicating the combination of beam and index for each of the plurality of measured values.

[0134] A step 117 comprises the mobile device(s) transmitting the at least one measurement report to the base station for use by the system. Step 105 comprises the system receiving the measurement reports from the set of mobile devices. The measurement reports comprise the results of the measurements.

[0135] Step 107 comprises the system determining the configuration of the reconfigurable intelligent surface based on the measurement reports received in step 105. Based on the collected measurements, e.g. minimum reporting or elaborate reporting, the system determines which RIS configuration improves coverage the most, e.g. best solves an identified coverage gap problem. Knowledge of actual SSBs and corresponding cell / base station used to measure a (strongest) RSRP is not per se needed for deciding the optimal RIS configuration. In the case of minimum reporting, as each mobile device reports on its given favorite / preferred RIS configuration, the RIS configuration with most votes may be selected, for example. If more than one RIS configuration ends up with the same highest number of votes, then the RIS configuration may be chosen randomly from among these options. In the case of minimum reporting, preferably, the OFF configuration is one of the candidate configurations and a mobile device is allowed to report the OFF configuration as its favorite / preferred configuration.

[0136] In the case of elaborate reporting, step 107 may comprises determining a score for each respective candidate configuration of the candidate configurations by applying weights to multiple quantities and adding the multiple weighted quantities and selecting the candidate configuration with the best score from the candidate configurations. The multiple quantities may, for example, comprise two or more of the following quantities:

[0137] 1. a quantity of mobile devices in a spatial area whose performance increased more than a predetermined amount when the reconfigurable intelligent surface used the respective candidate configuration compared to their performance indicator when the reconfigurable intelligent surface was switched off;

[0138] 2. a quantity of mobile devices in the spatial area whose performance decreased more than the predetermined amount when the reconfigurable intelligent surface used the respective candidate configuration compared to their performance indicator when the reconfigurable intelligent surface was switched off;

[0139] 3. a quantity of mobile devices in the spatial area whose performance exceeded a threshold when the reconfigurable intelligent surface used the respective candidate configuration and did not exceed the threshold when the reconfigurable intelligent surface was switched off;

[0140] 4. a quantity of mobile devices in the spatial area whose performance exceeded the threshold when the reconfigurable intelligent surface was switched off and did not exceed the threshold when the reconfigurable intelligent surface used the respective candidate configuration.

[0141] The performance of a respective mobile device of the set of mobile devices for a respective candidate configuration of the candidate configurations may be represented by the best performance indicator of multiple performance indicators of the respective mobile device, e.g. RSRPA3 for ai.. (XN-I in the example described above. Each of the multiple performance indicators is determined based on a measurement performed on a different wireless signal of the wireless signals.

[0142] The performance of a respective mobile device of the set of mobile devices for a respective candidate configuration of the candidate configurations may be determined based on the received power and / or the received quality of at least one of the wireless signals, for example. The higher the received power and received quality, the better the coverage, user throughput, spectral efficiency, energy efficiency, and localization accuracy.

[0143] The performance indicators may be the reported RSRPs, for example. Alternatively, the performance may be determined based on multiple performance indicators and / or based on a composite performance indicator which is a combination of multiple performance indicators, for example. The spatial area may be unlimited or limited, e.g. limited to the area of a coverage gap. Determining a quantity of mobile devices in a limited spatial area normally requires that the mobile devices in this limited spatial area are first identified.

[0144] Whether a performance increases, decreases, exceeds a threshold, or does not exceed a threshold may be determined based on a performance indicator which indicates the performance. A first type of performance indicator indicates a better performance when the performance indicator becomes higher. A second type of performance indicator indicates a better performance when the performance indicator becomes lower. With the second type of performance indicator, the performance may exceed the (performance) threshold when the performance indicator stays below an indicator threshold and the performance may stay below the (performance) threshold when the performance indicator exceeds the indicator threshold.

[0145] If a mobile device is capable or might be capable of reporting multiple performance indicators, the instruction to the mobile device may specify which one or more performance indicators to report. If a mobile device determines itself whether the performance increased or decreased more than the predetermined amount, then the instruction to the mobile device may specify the predetermined amount. If a mobile device determines itself whether the performance exceeded the threshold, then the instruction to the mobile device may specify the threshold.

[0146] Which quantities are to be used and / or which weights are to be used may be specified in an operator policy. An operator policy may be defined, for example, so as to select a RIS configuration that ensures coverage for the largest quantity of mobile devices or so as to select a RIS configuration that does not reduce the performance of mobile devices outside a coverage gap.

[0147] The above-mentioned quantities may be used, for example, to calculate one or more of the following fractions: a) Fraction of UEs that have high-frequency coverage under a given RIS configuration but did not have high-frequency coverage without the RIS; b) Fraction of UEs whose best RSRP has increased under a given RIS configuration compared to the case without the RIS; c) Fraction of UEs whose best RSRP has decreased under a given RIS configuration compared to the case without the RIS.

[0148] Step 109 comprises the system causing the reconfigurable intelligent surface to use the determined configuration determined in step 107. Step 109 may comprise transmitting a further configuration message to the reconfigurable intelligent surface or instructing another system to transmit a further configuration message to the reconfigurable intelligent surface. The further configuration message specifies the configuration determined in step 107. A step 125 comprises the reconfigurable intelligent surface receiving the further configuration message from the system or from the other system. A step 127 comprises the reconfigurable intelligent surface using the configuration specified in the further configuration message, typically with an undefined end time.

[0149] A third embodiment of the method of determining a configuration for a reconfigurable intelligent surface is shown in Fig. 9. This third embodiment of Fig. 9 is an extension of the second embodiment of Fig. 4. In the embodiment of Fig. 9, step 100 of Fig. 4 comprises steps 141 and 141 and step 103 of Fig. 4 comprises a step 145.

[0150] Step 141 comprises the system determining a target area in which an estimated or measured performance does not exceed a threshold, e.g. fed by measurements from an MDT (Minimization of Drive Test) system. The target area, i.e. the problem area, may correspond, for example, to a coverage gap, e.g. on a high-frequency carrier. In step 141, the presence, approximate location and nature of the problem area is identified. This may be done by mobile devices experiencing a lack of coverage on a high-frequency carrier and reporting this (e.g. via a covering low-frequency carrier) to their serving base station, along with a mobile device-reported or network-determined (approximate or precise) user location. Mobile devices may be instructed to measure their coverage status via SSB and / or CSI-RS RSRP measurements on all frequencies or a selected set thereof. Mobile devices with a lack of coverage (e.g. too low or unmeasurable RSRP) on the high-frequency carrier may have coverage (e.g. a sufficiently high RSRP) on a low-frequency carrier in the area of the noted high-frequency coverage gap, for example.

[0151] Another way of identifying the target / problem area involves a radio network planning tool or a ray tracing tool predicting an area of poor coverage. The RIS may be deployed at a feasible and promising location (that is estimated to have good potential to resolve the identified coverage gap) in response to identifying the coverage gap. When the system performs step 141, the system is typically aware of the RIS location and its potential to improve coverage in the target area. For example, the system may be aware of its potential to resolve an identified coverage gap on an high-frequency carrier in the overall coverage area of one or more base stations.

[0152] Step 143 comprises the system selecting one or more base stations based on the target area determined in step 141. Step 145 comprises instructing each respective base station of the one or more base stations selected in step 143 to transmit an instruction message to one or more mobile devices covered by the respective base station. Each respective base station may be instructed, for example, to broadcast the instruction message and / or transmit the instruction message individually to one or more mobile devices served by the respective base station.

[0153] One possibility is to instruct all the mobile devices covered by the selected base stations via e.g. a broadcast message. Another possibility is to instruct via broadcast (for idle mobile devices) or instruct via individual transmissions (for active mobile devices) only selected mobile devices within the coverage of the selected base stations that are potentially reached via the reflected signals from the RIS.

[0154] For example, the measurements of mobile devices with a location near the RIS location and / or near the identified high-frequency coverage gap are most relevant. Active mobile devices with a location near the RIS location and / or near the target / problem area may be selected by the system itself. For idle mobile devices, the measurement instruction may specify the RIS location and / or the target area to allow the mobile devices to determine themselves whether to perform and report measurements or not. Thus, not all devices that receive the broadcast are instructed to perform the measurements. By instructing all relevant mobile devices to measure the e.g. high-frequency signals from the surrounding base stations (i.e. not only mobile devices within the coverage gap), the system may derive the broader impact of configuring the RIS with the purpose of mitigating the identified e.g. high-frequency coverage gap. For example, mobile devices not in the coverage gap may also be affected by a change in the RIS configuration.

[0155] To prevent that too many mobile devices receive a broadcast instruction to perform and report measurements, the measurement instruction may comprise a coin bias to allow the mobile devices to determine themselves whether to perform and report measurements or not based on the flip of the biased coin.

[0156] Fig. 10 depicts a block diagram illustrating an exemplary data processing system that may perform the method as described with reference to Figs. 3, 4, and 9.

[0157] As shown in Fig. 10, the data processing system 300 may include at least one processor 302 coupled to memory elements 304 through a system bus 306. As such, the data processing system may store program code within memory elements 304. Further, the processor 302 may execute the program code accessed from the memory elements 304 via a system bus 306. In one aspect, the data processing system may be implemented as a computer that is suitable for storing and / or executing program code. It should be appreciated, however, that the data processing system 300 may be implemented in the form of any system including a processor and a memory that is capable of performing the functions described within this specification.

[0158] The memory elements 304 may include one or more physical memory devices such as, for example, local memory 308 and one or more bulk storage devices 310. The local memory may refer to random access memory or other non-persistent memory device(s) generally used during actual execution of the program code. A bulk storage device may be implemented as a hard drive or other persistent data storage device. The processing system 300 may also include one or more cache memories (not shown) that provide temporary storage of at least some program code in order to reduce the number of times program code must be retrieved from the bulk storage device 310 during execution.

[0159] Input / output (I / O) devices depicted as an input device 312 and an output device 314 optionally can be coupled to the data processing system. Examples of input devices may include, but are not limited to, a keyboard, a pointing device such as a mouse, or the like. Examples of output devices may include, but are not limited to, a monitor or a display, speakers, or the like. Input and / or output devices may be coupled to the data processing system either directly or through intervening I / O controllers.

[0160] In an embodiment, the input and the output devices may be implemented as a combined input / output device (illustrated in Fig. 10 with a dashed line surrounding the input device 312 and the output device 314). An example of such a combined device is a touch sensitive display, also sometimes referred to as a “touch screen display” or simply “touch screen”. In such an embodiment, input to the device may be provided by a movement of a physical object, such as e.g. a stylus or a finger of a user, on or near the touch screen display.

[0161] A network adapter 316 may also be coupled to the data processing system to enable it to become coupled to other systems, computer systems, remote network devices, and / or remote storage devices through intervening private or public networks. The network adapter may comprise a data receiver for receiving data that is transmitted by said systems, devices and / or networks to the data processing system 300, and a data transmitter for transmitting data from the data processing system 300 to said systems, devices and / or networks. Modems, cable modems, and Ethernet cards are examples of different types of network adapter that may be used with the data processing system 300.

[0162] As pictured in Fig. 10, the memory elements 304 may store an application 318. In various embodiments, the application 318 may be stored in the local memory 308, he one or more bulk storage devices 310, or separate from the local memory and the bulk storage devices. It should be appreciated that the data processing system 300 may further execute an operating system (not shown in Fig. 10) that can facilitate execution of the application 318. The application 318, being implemented in the form of executable program code, can be executed by the data processing system 300, e.g., by the processor 302. Responsive to executing the application, the data processing system 300 may be configured to perform one or more operations or method steps described herein.

[0163] Various embodiments of the invention may be implemented as a program product for use with a computer system, where the program(s) of the program product define functions of the embodiments (including the methods described herein). In one embodiment, the program(s) can be contained on a variety of non-transitory computer-readable storage media, where, as used herein, the expression “non-transitory computer readable storage media” comprises all computer-readable media, with the sole exception being a transitory, propagating signal. In another embodiment, the program(s) can be contained on a variety of transitory computer-readable storage media. Illustrative computer-readable storage media include, but are not limited to: (i) non-writable storage media (e.g., read-only memory devices within a computer such as CD-ROM disks readable by a CD-ROM drive, ROM chips or any type of solid-state non-volatile semiconductor memory) on which information is permanently stored; and (ii) writable storage media (e.g., flash memory, floppy disks within a diskette drive or hard-disk drive or any type of solid-state random-access semiconductor memory) on which alterable information is stored. The computer program may be run on the processor 302 described herein. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0164] The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of embodiments of the present invention has been presented for purposes of illustration, but is not intended to be exhaustive or limited to the implementations in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope of the present invention.

[0165] The embodiments were chosen and described in order to best explain the principles and some practical applications of the present invention, and to enable others of ordinary skill in the art to understand the present invention for various embodiments with various modifications as are suited to the particular use contemplated.

Claims

CLAIMS:

1. A system (1) for determining a configuration for a reconfigurable intelligent surface (21), the reconfigurable intelligent surface (21) being able to alter the propagation environment of wireless signals in a controlled manner, the system (1) including at least one processor (5) configured to:- cause the reconfigurable intelligent surface (21) to successively use a plurality of candidate configurations during a plurality of time intervals, each of the time intervals corresponding to one of the candidate configurations,- cause a set of mobile devices (31-36) to perform measurements on wireless signals transmitted by one or more base stations in the plurality of time intervals and report the measurements,- receive measurement reports from the set of mobile devices (31-36), the measurement reports comprising results of the measurements,- determine the configuration of the reconfigurable intelligent surface (21) based on the measurement reports, and- cause the reconfigurable intelligent surface (21) to use the determined configuration.

2. A system (1) as claimed in claim 1, wherein the at least one processor (5) is configured to cause the set of mobile devices (31-36) to perform further measurements on further wireless signals transmitted by the one or more base stations (11) in one or more further time intervals when the reconfigurable intelligent surface (21) is switched off and wherein the measurement reports further comprise results of the further measurements.

3. A system (1) as claimed in claim 2, wherein the one or more further time intervals comprise multiple further time intervals in between the time intervals and the at least one processor (5) is configured to cause the reconfigurable intelligent surface (21) to switch off during the multiple further time intervals.

4. A system (1) as claimed in any one of claims 1 to 3, wherein the at least one processor (5) is configured to:- determine from the measurement reports, for each respective candidate configuration of the candidate configurations, at least one of: a) a first quantity of mobile devices (31-36) in a spatial area whose performance increased more than a predetermined amount when the reconfigurable intelligent surface (21) used the respective candidate configuration compared to their performance indicator when the reconfigurable intelligent surface (21) was switched off, b) a second quantity of mobile devices (31-36) in the spatial area whose performance decreased more than the predetermined amount when the reconfigurable intelligent surface (21) used the respective candidate configuration compared to their performance indicator when the reconfigurable intelligent surface (21) was switched off, c) a third quantity of mobile devices (31-36) in the spatial area whose performance exceeded a threshold when the reconfigurable intelligent surface (21) used the respective candidate configuration and did not exceed the threshold when the reconfigurable intelligent surface (21) was switched off, and d) a fourth quantity of mobile devices (31-36) in the spatial area whose performance exceeded the threshold when the reconfigurable intelligent surface (21) was switched off and did not exceed the threshold when the reconfigurable intelligent surface (21) used the respective candidate configuration, and- determine the configuration of the reconfigurable intelligent surface (21) by selecting one of the candidate configurations based on at least one of the first quantity, the second quantity, the third quantity, and the fourth quantity.

5. A system (1) as claimed in claim 4, wherein the performance of a respective mobile device of the set of mobile devices (31-36) for a respective candidate configuration of the candidate configurations is represented by the best performance indicator of multiple performance indicators of the respective mobile device, each of the multiple performance indicators being determined based on a measurement performed on a different wireless signal of the wireless signals.

6. A system (1) as claimed in claim 4 or 5, wherein the performance of a respective mobile device of the set of mobile devices (31-36) for a respective candidate configuration of the candidate configurations is determined based on the received power and / or the received quality of at least one of the wireless signals.

7. A system (1) as claimed in any one of the preceding claims, wherein the wireless signals comprise reference signals.

8. A system (1) as claimed in any one of the preceding claims, wherein each of the candidate configurations comprises a different phase vector, each phase vector prescribing the phase shift applied to the wireless signals as received from the one or more base stations at each of the elements of the reconfigurable intelligent surface (21) in a corresponding time interval of the plurality of time intervals.

9. A system (1) as claimed in any one of the preceding claims, wherein the at least one processor (5) is configured to determine a target area (17) in which an estimated or measured performance does not exceed a threshold, select the one or more base stations (11) based on the target area, and cause the set of mobile devices (31-36) to perform measurements on the wireless signals by instructing each respective base station of the one or more base stations to transmit an instruction message to one or more mobile devices covered by the respective base station.

10. A system (1) as claimed in claim 9, wherein the at least one processor (5) is configured to instruct each respective base station of the one or more base stations (11) to broadcast the instruction message and / or transmit the instruction message individually to one or more mobile devices served by the respective base station.

11. A system (1) as claimed in claim 9 or 10, wherein the at least one processor (5) is configured to determine the target area by determining a coverage gap (17).

12. A system (1) as claimed in claim 11, wherein the at least one processor (5) is configured to determine the target area by determining a coverage gap (17) on a high- frequency carrier.

13. A mobile device (31-33) for use with the system (1) of any one of claims 1 to 12, the mobile device (31-33) including at least one processor (45) configured to:- receive an instruction message from a base station (11), the instruction message comprising a schedule determined by the system (1), the schedule specifying a plurality of time intervals in which the mobile device (31-33) is instructed to perform measurements on wireless signals transmitted by one or more base stations (11) via one or more beams, and an index for each of the plurality of time intervals,- perform the measurements on the wireless signals in the plurality of time intervals,- create at least one measurement report, the at least one measurement report comprising results of the measurements, the results being determined by averaging a plurality of measured values per combination of beam and index, the plurality of measured values being measured in a time interval associated with the index, or the results enabling the system to average the plurality of measured values per combination of beam and index, and- transmit the at least one measurement report to the base station (11) or a different base station for use by the system (1).

14. A reconfigurable intelligent surface (21) for use with the system (1) of any one of claims 1 to 12, the reconfigurable intelligent surface (21) being able to alter the propagation environment of wireless signals in a controlled manner and including at least one processor (25) configured to:- receive a configuration message from the system (1) or from another system, the configuration message comprising a schedule determined by the system (1) and indicating a plurality of candidate configurations, the schedule specifying a plurality of time intervals in which the reconfigurable intelligent surface (21) is instructed to successively use the plurality of candidate configurations, each of the time intervals corresponding to one of the candidate configurations, and- successively use the plurality of candidate configurations during the plurality of time intervals.

15. A method of determining a configuration for a reconfigurable intelligent surface, the reconfigurable intelligent surface being able to alter the propagation environment of wireless signals in a controlled manner, the method including:- causing (101) the reconfigurable intelligent surface to successively use a plurality of candidate configurations during a plurality of time intervals, each of the time intervals corresponding to one of the candidate configurations;- causing (103) a set of mobile devices to perform measurements on wireless signals transmitted by one or more base stations in the plurality of time intervals and report the measurements;- receiving (105) measurement reports from the set of mobile devices, the measurement reports comprising results of the measurements;- determining (107) the configuration of the reconfigurable intelligent surface based on the measurement reports; and- causing (109) the reconfigurable intelligent surface to use the determined configuration.

16. A method of performing measurements at a mobile device, the method including:- receiving (111) an instruction message from a base station at the mobile device, the instruction message comprising a schedule determined by the system, the schedule specifying a plurality of time intervals in which the mobile device is instructed to perform measurements on wireless signals transmitted by one or more base stations via one or more beams, and an index for each of the plurality of time intervals;- performing (113) the measurements on the wireless signals in the plurality of time intervals;- creating (115) at least one measurement report, the at least one measurement report comprising results of the measurements, the results being determined by averaging a plurality of measured values per combination of beam and index, the plurality of measured values being measured in a time interval associated with the index, or the results enabling the system to average the plurality of measured values per combination of beam and index; and- transmitting (117) the at least one measurement report to the base station or a different base station for use by the system.

17. A method of configuring a reconfigurable intelligent surface, the reconfigurable intelligent surface being able to alter the propagation environment of wireless signals in a controlled manner, the method comprising:- receiving (121) a configuration message from the system or from another system, the configuration message comprising a schedule determined by the system and indicating a plurality of candidate configurations, the schedule specifying a plurality of time intervals in which the reconfigurable intelligent surface is instructed to successively use the plurality of candidate configurations, each of the time intervals corresponding to one of the candidate configurations; and- successively using (123) the plurality of candidate configurations during the plurality of time intervals.

18. A computer program or suite of computer programs comprising at least one software code portion or a computer program product storing at least one software code portion, the software code portion, when run on a computer system, being configured for performing the method of claim 15, 16 or 17.

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