Determining the operational mode of reconfigurable intelligent surface

Abstract

There is provided a method for operating a reconfigurable intelligent surface (RIS) which is associated with a network node operating on a first carrier frequency. The method is performed by the RIS. The method comprises detecting an incoming signal which has a second carrier frequency and determining whether the detected incoming signal is associated with the network node. The method further comprises operating the RIS according to an operational mode of the RIS. The operational mode of the RIS is determined based at least on whether the detected incoming signal is associated with the network node.

Description

DETERMINING THE OPERATIONAL MODE OF RECONFIGURABLE INTELLIGENT SURFACETECHNICAL FIELD

[0001] This disclosure relates to determining the operational mode of reconfigurable intelligent surface (RIS).BACKGROUND

[0002] Intelligent reflecting surface (IRS), also known as reconfigurable intelligent surface (RIS), is an emerging technology product that is capable of intelligently manipulating the propagation of electromagnetic waves. IRS / RIS (hereinafter just, "RIS”) is composed of a 2-dimensional array of reflecting elements, where each reflecting element acts as a passive reconfigurable scatterer - a piece of manufactured material - which can be programmed to change an impinging electro-magnetic wave in a customized way.

[0003] The reflecting elements are usually low-cost passive surfaces that do not require dedicated power sources, and the radio waves impinged upon them can be forwarded without the need of employing a power amplifier or a radio frequency (RF) chain. Moreover RIS can potentially work in a full duplex mode without significant selfinterference and requires only low-rate control link(s) or backhaul connections. RIS can be flexibly deployed due to its low weight and low power consumption. Especially RIS is of interest in stationary or low-mobility networks, in which the transmission parameters can be well planned. For example, blockages / tree foliage can be bypassed through RIS-assisted communication. 3GPP TSG RAN Rel-18 workshop, June 2021 .SUMMARY

[0004] RISs can be used to cover coverage holes, e.g., specific corner areas, which cannot be properly covered by deployed base stations (e.g., gNBs), etc. However, certain challenges presently exist in using RISs.

[0005] For example, RISs may cause interferences to the surrounding nodes, e.g., gNBs and / or user equipments (UEs), neighbor networks, and potentially other systems outside of the 3GPP band. Particularly, depending on the angle of receiving signal waves (hereinafter just "signals”) at RISs, the carrier frequency, and / or the energy of the received signals, the RISs may reflect unwanted signals from / towards their own operator or other operators in different carriers. Such unintended reflection of the signals may affect the overall performance of the networks. The RISs may also reflect signals outside of the 3GPP band, which are for other systems such as radar, fixed link, etc., which could disturb the performance of the other systems. These unintentional reflections of signals by RISs need to be addressed by regulators. This is especially due to the full-duplex nature of RISs as well as because the RISs always reflect some signals.

[0006] Another potential issue with using RISs is that if another transmitter is close to an RIS, the power from said another transmitter may drive the circuitry of the RIS into saturation. This would create emissions thatmight impact other operators and would also cause large distortion towards the owner operator.

[0007] For the foregoing reasons, there is a need for a method to set the operational mode(s) of RIS(s) differently based on the environments of the RIS(s). Accordingly, in some embodiments of this disclosure, there is provided a method to determine the operational mode(s) of RIS(s) based on the properties of signals received at the RIS(s).

[0008] More specifically, in one aspect of the embodiments of this disclosure, there is provided a method for operating a reconfigurable intelligent surface (RIS) which is associated with a network node operating on a first carrier frequency. The method is performed by the RIS. The method comprises detecting an incoming signal which has a second carrier frequency and determining whether the detected incoming signal is associated with the network node. The method further comprises operating the RIS according to an operational mode of the RIS. The operational mode of the RIS is determined based at least on whether the detected incoming signal is associated with the network node, and the first and second carrier frequencies are the same or different.

[0009] In another aspect of the embodiments of this disclosure, there is provided a method for operating a reconfigurable intelligent surface (RIS) which is associated with a network node operating on a first carrier frequency. The method is performed by the network node. The method comprises receiving, from the RIS, a first message which includes information about an incoming signal detected at the RIS. The incoming signal has a second carrier frequency, and the information about the detected incoming signal comprises an indication of whether the detected incoming signal is associated with the network node. The method also comprises, based at least on whether the detected incoming signal is associated with the network node, determining an operational mode of the RIS, and transmitting, to the RIS, a second message indicating the determined operational mode of the RIS. The first and second carrier frequencies are the same or different.

[0010] In a different aspect of the embodiments of this disclosure, there is provided a method a method for operating a reconfigurable intelligent surface (RIS) which is associated with a network node. The method is performed by the network node. The method comprises receiving, from the RIS, a first message indicating an operational mode of the RIS, and determining whether the indicated operational mode of the RIS is acceptable or not. The method also comprises, based at least on the determination, transmitting, to the RIS, a second message indicating whether the indicated operational mode of the RIS is acceptable or not.

[0011] In a different aspect of the embodiments of this disclosure, there is provided a computer program comprising instructions which when executed by processing circuitry cause the processing circuitry to perform the method of any one of the above embodiments.

[0012] In a different aspect of the embodiments of this disclosure, there is provided a carrier containing the computer program of the above embodiments. The carrier is one of an electronic signal, an optical signal, a radio signal, and a computer readable storage medium.

[0013] In a different aspect of the embodiments of this disclosure, there is provided a reconfigurable intelligent surface (RIS) which is associated with a network node operating on a first carrier frequency. The RIS is configured to detect an incoming signal which has a second carrier frequency and determine whether the detected incoming signal is associated with the network node. The RIS is further configured to operate the RIS according to an operational mode of the RIS. The operational mode of the RIS is determined based at least on whether the detected incoming signal is associated with the network node, and the first and second carrier frequencies are the same or different.

[0014] In a different aspect of the embodiments of this disclosure, there is provided a network node for operating a reconfigurable intelligent surface (RIS) which is associated with the network node operating on a first carrier frequency. The network node is configured to receive, from the RIS, a first message which includes information about an incoming signal detected at the RIS. The incoming signal has a second carrier frequency, and the information about the detected incoming signal comprises an indication of whether the detected incoming signal is associated with the network node. The network node is also configured to, based at least on whether the detected incoming signal is associated with the network node, determine an operational mode of the RIS, and transmit, to the RIS, a second message indicating the determined operational mode of the RIS. The first and second carrier frequencies are the same or different.

[0015] In a different aspect of the embodiments of this disclosure, there is provided a network node for operating a reconfigurable intelligent surface (RIS) which is associated with the network node. The network node is configured to receive, from the RIS, a first message indicating an operational mode of the RIS, and determine whether the indicated operational mode of the RIS is acceptable or not. The network node is further configured to, based at least on the determination, transmit, to the RIS, a second message indicating whether the indicated operational mode of the RIS is acceptable or not.

[0016] In a different aspect of the embodiments of this disclosure, there is provided an apparatus comprising processing circuitry and a memory. The memory contains instructions executable by said processing circuitry. The apparatus is operative to perform the method of any one of the above embodiments.

[0017] The embodiments of this disclosure allow providing an RIS-assisted communication while avoiding severe interferences to other networks or systems. More specifically, in some embodiments, the operational mode of an RIS is determined depending on if received signal / beam is associated with a controlling gNB of the RIS such that severe interference to the surrounding nodes and neighbor networks or other systems is minimized. In this way, while the RIS helps in coverage extension, the negative impact to other spectrum users is minimized. This addresses one of the main issues of RIS-assisted networks and facilitates the feasibility / integration of RISs into the network.BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate various embodiments.

[0019] FIG. 1 illustrates an exemplary scenario where the embodiments of this disclosure can be applied.

[0020] FIG. 2 shows a process according to some embodiments.

[0021] FIG. 3 shows a process according to some embodiments.

[0022] FIG. 4 shows a process according to some embodiments.

[0023] FIG. 5 shows a process according to some embodiments.

[0024] FIG. 6 shows a process according to some embodiments.

[0025] FIG. 7 shows a process according to some embodiments.

[0026] FIG. 8 shows an apparatus according to some embodiments.

[0027] FIG. 9 shows an apparatus according to some embodiments.DETAILED DESCRIPTION

[0028] As discussed above, one of the functions of an RIS is to extend the network coverage of a network node (e.g., a base station) associated with the RIS and / or cover a hole in the network coverage of the network node.

[0029] In this disclosure, a network node (e.g., a base station) associated with an RIS is also referred to as "a controlling network node” (e.g., a controlling base station). Also, in this disclosure, that an RIS and a base station are associated with each other may mean that the RIS and the base station are owned and / or controlled by the same network operator, and / or the network operator may use the RIS to supplement the operations of the base station. In other words, the controlling network node is responsible for controlling the operation of the RIS. Note that even though a "base station” in this disclosure is not limited to any particular generation (e.g., 4G, 5G, etc.) of network, for simple referencing purpose only, in the remaining disclosure, a base station will be referred as gNB - i.e., a base station in a 5G network.

[0030] As mentioned above, an RIS can be used to cover a hole in the network coverage of its controlling gNB. For example, when the controlling gNB cannot properly cover certain areas (e.g., corner areas) of its network coverage region due to, for example, blockages, tree foliage, etc., the RIS can be used to cover such network coverage hole. This is illustrated in FIG. 1.

[0031] FIG. 1 shows an exemplary scenario 100 where the embodiments of this disclosure can be applied. In the scenario 100, an RIS 102 is provided to extend the network coverage of its controlling gNB 104. For example, in the scenario 100, a direct signal path 120 between the controlling gNB 104 and a user equipment (UE) 106 isblocked by tree foliage 108. Due to this blockage, wireless signals transmitted from the controlling gNB 104 cannot be received properly at the UE 106 via the direct signal path 120.

[0032] Thus, in the scenario 100, instead of using the direct signal path 120, the RIS 102 is used to forward the wireless signals from the controlling gNB 104 to the UE 106 such that the controlling gNB 104 and the UE 106 can communicate with each other even in the presence of the tree foliage 108 in the direct signal path 120. However, certain problems exist in the use of the RIS 102.

[0033] One of the problems is that because the operation of an RIS is not necessarily restricted only to the carrier (a.k.a., carrier wave or carrier signal) of its network operator that owns and / or controls the RIS, the operation of the RIS may impact (e.g., reflect) other carriers that are not intended to be impacted by the RIS. Such unintended impact causes severe interferences or other degradations to the surrounding nodes / networks.

[0034] This means that, in case the surrounding nodes / networks are owned and / or controlled by other network operators, the operation of the RIS may cause unintentional reflection of the carriers of the other network operators, thereby causing an unpredictable propagation environment for the other network operators and impacting beamforming, beam management, etc. of the other network operators. This is illustrated in FIG. 1.

[0035] In FIG. 1 , the gNB 104 is controlled and / or operated by a first network operator, i.e., the network operator of the RIS 102, while the gNB 112 is controlled and / or operated by a second network operator which is different from the first network operator. As explained above, the RIS 102 is configured to reflect wireless signals transmitted from the gNB 104 towards the UE 106. However, due to the RIS 102's close proximity to the gNB 112, the RIS 102 may unintentionally reflect wireless signals transmitted from the gNB 112 towards the UE 106. This unintentional reflection may cause an unpredictable propagation environment for the second network operator and may impact beamforming managements performed at the gNB 112.

[0036] Furthermore, in case the operation of the RIS covers a wideband range, the operation of the RIS may even impact signals that are outside of the 3GPP signal band. For instance, the RIS may unintentionally reflect signals of a radar system, thereby interfering with the operation of the radar system if there are different unpredictably time varying reflections within its frequency band. The characteristics of this unintentional reflection may change more as the subject signals are further out from the intended signal band.

[0037] Another problem occurs when a transmitter from another network operator or system is located close to the RIS and transmits / receives signals at high powers. In this case, the circuits in the RIS can be driven into saturation, leading to the RIS generating intermodulation products, which would cause interference towards the RIS network operator and / or other network operators.

[0038] Because of the problems discussed above, there is a need for a method and an apparatus fordetermining the operational mode of an RIS such that strong interferences caused by unintended reflection by the RIS can be avoided and the RIS is operated only when it does not make serious problems for other network(s).

[0039] FIG. 2 shows a process 200 for determining the operational mode of an RIS, e.g., the RIS 102 shown in FIG. 1, according to some embodiments. The process 200 may begin with step s202.

[0040] The step s202 comprises the RIS detecting an incoming signal (e.g., an impinging signal - i.e., a strong signal from a particular direction). The received signal may be from the controlling gNB of the RIS, e.g., the gNB 102, or from other network nodes. Also, the carrier frequency of the received signal may be same as or different from the carrier frequency used by the controlling gNB. Depending on the deployment scenario, the detection of the incoming signal may only take place in downlink (DL) slots to only address interference from other gNBs.

[0041] One implementation of the RIS is an antenna matrix that is connected to ground via some resistorcapacitor (RC) circuitries. Some elements of the RIS may be connected to a receiver and may be capable of detecting the amount and the direction of impinging energy of the received signal. In the RIS, there can be many types of switchable reactive components, e.g., allowing for a phase shift between 0 and n, or higher resolutions. Also, the RIS may be capable of determining the total and / or the individual energies in different carrier frequencies and / or directions.

[0042] The step s202 of detecting an incoming signal includes not only just determining whether the signal is received at the RIS but also detecting one or more characteristics of the signal, which include but are not limited to the direction of receiving the signal at the RIS, the amount of energy (i.e., strength) of the received signal corresponding to the direction, the cell / carrier frequency of the received signal, etc.

[0043] After detecting the incoming signal, the process 200 may proceed to step s204. The step s204 comprises the RIS determining whether the detected signal is associated with its controlling gNB or not. In this disclosure, that a detected signal is associated with a gNB means that the transmission of the detected signal is controlled and / or triggered by the gNB.

[0044] In some embodiments, such determination is made based on the direction of receiving the detected signal. For example, the RIS, e.g., the RIS 102, may know or be able to determine the direction of its controlling gNB, e.g., the gNB 104, with respect to the RIS 102. Then, in the step s204, the RIS may compare the direction of receiving the detected signal to the direction of its controlling gNB. In case they are the same or the difference between the two directions is within a permissible range, the RIS may determine that the detected signal i s associated with its controlling gNB. Otherwise, the RIS may determine that the detected signal is not associated with its controlling gNB.

[0045] In determining the direction of its controlling gNB with respect to the RIS, the RIS may obtain the position of the RIS and the position of its controlling gNB first, and then determine the direction of its controlling gNBbased on the obtained positions. For example, if a geographical coordinate (e.g., GPS coordinate) of the RIS is (A, B) and a geographical coordinate of its controlling gNB is (A', B’), the direction of the controlling gNB with respect to the RIS can be determined as a directional component of the vector v = (A - A' , B - B').

[0046] Alternatively or additionally, the RIS may determine whether the detected signal is associated with its controlling gNB based on the carrier frequency of the detected signal. For example, the RIS may have or may be able to obtain the carrier frequency of its controlling gNB and may compare the carrier frequency of its controlling gNB to the carrier frequency of the detected signal. In case they are the same, the RIS may determine that the detected signal is associated with the controlling gNB. On the contrary, in case they are different, the RIS may determine that the detected signal is not associated with the controlling gNB.

[0047] There may be a scenario where the RIS 102 detects multiple incoming signals in the step s202. In such case, the step s204 may be performed for each of the detected signals. For the purpose of simple explanation, it will be assumed that the RIS detects only one incoming signal in the step s202.

[0048] Referring back to FIG. 2, after determining whether the detected signal is associated with the controlling gNB, the process 200 may proceed to step s206.

[0049] The step s206 comprises the RIS or the controlling gNB determining operational mode of the RIS based on the information obtained in the step s202, e.g., the direction of receiving the incoming signal at the RIS, the amount of energy of the incoming signal, the cell frequency (carrier frequency) of the incoming signal, etc., and the information obtained in the step s204, i.e., whether the incoming signal is associated with the controlling gNB. Additionally, the operational mode of the RIS may be determined based on the carrier frequency of the controlling gNB. Note that operational modes available at RISs may vary depending on the capabilities of the RISs. The determination of the operational mode of the RIS is related to reducing interference to / from adjacent networks and on adjacent carriers, as explained below.

[0050] In one example, in case it is determined in the step s204 that the incoming signal is associated with the controlling gNB, the operational mode of the RIS may be set to a reflection mode (e.g., a coherent reflection mode) in which the RIS is configured to reflect signals received at the RIS in a particular (e.g., narrow) direction. One or more configurations of the RIS in the reflection mode may be determined by the controlling gNB.

[0051] On the other hand, in case it is determined in the step s204 that the incoming signal is not associated with the controlling gNB - meaning that the signal is not supposed to be reflected -, the operational mode of the RIS may be set to a disabling mode in which the functionality or the RIS is disabled, a reduced functionality mode (either in reflection angles, reflection power, etc.) in which one or more functions of the RIS is reduced, a partial enabling / disabling mode in which some functionalities / parts of the RIS is selectively enabled / disabled, or any other specific mode operating according to a specific configuration of the RIS.

[0052] Here, the specific configuration of the RIS may be obtained by finding a safe reflection angle, e.g., during the network planning, which does not affect the other nodes or adjacent networks / carriers. In the scenario 100 shown in FIG. 1, the transmission direction of the signal wave 170 corresponds to the safe reflection angle because transmitting signal waves at such direction do not affect the operations of the gNB 112.

[0053] The safe angle can be determined by the controlling gNB or the 0AM (Operations, Administration, and Management) using different methods. For example, in some embodiments, the safe angle may be determined based on Synchronization Signal Block (SSB) or Channel State Information Reference Signal (CSI-RS) reports from the surrounding network nodes, e.g., the gNB 112.

[0054] More specifically, in one example, one or more user equipments (UEs) may transmit Sounding Reference Signals (SRSs) to the gNB 112, and the gNB 112 may perform an uplink (UL) measurements on those SRSs. After performing the UL measurements, the gNB 112 may report to the RIS and / or the gNB 104 a measurement report indicating the result of the UL measurement. This measurement report may provide to the RIS and / or the gNB 104 information about the direction(s) of signal path(s) between the gNB 112 and the UEs. Then the RIS and / or the gNB 104 may set the safe angle such that transmission direction of a signal at the reflection angle of the RIS does not intersect the signal path(s). In some embodiments, instead of performing actual UL measurements, a digital twin simulation may be used.

[0055] Alternatively, in other embodiments, the controlling gNB or the RIS may determine the safe angle based on the position of the RIS and the positions of UEs and / or network nodes that should not be interfered if these information is available. More specifically, in one example, the signal path(s) used by the gNB 112 for communicating with UEs may be determined based on the positions of the UEs and the gNB 112, and the reflection angle of the RIS may be set such that transmission direction of a signal from the RIS at the reflection angle does not intersect the signal path(s).

[0056] Another specific mode of the RIS to use in case the incoming signal is not associated with the controlling gNB is a scattering mode in which there is no coherent reflection from the RIS. That is, in the scattering mode, the RIS reflects a minimum amount of coherent energy in a direction. By configuring the RIS such that there is no coherent reflection of wireless signals reaching the RIS, the energy of the reflected signals will not be focused at a certain direction, and thus the interference caused by such reflected signals can be reduced. The other specific mode of the RIS is an absorption mode at which the RIS absorbs the wireless signals reaching the RIS, thereby preventing or reducing the interference that could have been caused by the reflected signals.

[0057] As briefly mentioned above, one of the different specific modes is a partial enabling / disabling mode. In one example of the partial enabling / disabling mode, if the RIS determines that the receiving (RX) power of a signal is above a certain threshold, then the RIS disconnects its circuits from the antenna elements in order to avoidsaturation of the circuits.

[0058] Other specific modes of the RIS include but are not limited to not operating the RIS for some time upon detecting that the incoming signal is not associated with its controlling g N B, performing a continuation detection of incoming signals, or triggering an immediate mode change.

[0059] As explained above, in case the RIS determines that the incoming signal is not associated with its controlling g NB, the RIS prevents or reduces the reflection of the incoming signal or reflects the incoming signal at a certain safe angle. By doing that, the RIS can reduce and / or minimize its interference to other network nodes.

[0060] As shown in FIG. 3, in some embodiments, once the operational mode of the RIS is determined, the RIS may notify its controlling gNB about the determined operational mode of the RIS. For example, in step s302 of a process 300 shown in FIG. 3, the RIS transmits to the controlling gNB a notification signal which indicates the determined operational mode of the RIS. In some embodiments, the notification signal may comprise information about the detected incoming signal. The information about the detected incoming signal may comprise one or more of: a direction receiving the incoming signal at the RIS, strength of the incoming signal received at the RIS; and / or the carrier frequency of the incoming signal. Alternatively, the notification signal and the information about the detected incoming signal can be sent to the gNB separately.

[0061] Upon notifying the determined operational mode of the RIS to the controlling gNB, in step s304, the RIS receives from the controlling gNB a response signal indicating whether the notification signal was successfully received at the controlling gNB. Additionally or alternatively, the response signal may indicate whether the controlling gNB agrees or disagrees with the determined operational mode of the RIS.

[0062] In some embodiments, the controlling gNB may send to the RIS a configuration of the RIS corresponding to the determined operational mode of the RIS. The configuration of the RIS may be included in the response signal or may be provided to the RIS separately from the response signal. In other embodiments, in case the controlling gNB disagrees with the operational mode of the RIS determined by the RIS, the controlling gNB may determine a new operational mode of the RIS based on the received information about the detected incoming signal and may send to the RIS a configuration of the RIS corresponding to the newly determined operational mode.

[0063] In the embodiments shown in FIG. 3, the RIS determines the operational mode of the RIS. However, as shown in FIG. 4, in some embodiments, the controlling gNB, not the RIS, may determine the operational mode of the RIS. More specifically, in FIG. 4, after the RIS determines that the incoming signal is not associated with its controlling gNB, in step s402, the RIS informs the controlling gNB information about the detected incoming signal. The information about the detected incoming signal may comprise one or more of: a direction receiving the incoming signal at the RIS, strength of the incoming signal received at the RIS; and / or the carrier frequency of the incomingsignal. Additionally or alternatively, the information about the detected incoming signal may include an indication of whether the detected incoming signal is associated with the controlling gNB and / or an indication of a need to change the operational mode of the RIS. In some embodiments, in addition to informing the controlling gNB the information about the detected signal, the RIS may also inform the controlling gNB that the operational mode of the RIS needs to be changed.

[0064] Then, in step s404, the controlling gNB may determine the operational mode of the RIS based on the received information about the detected incoming signal. The different methods of determining the operational mode of the RIS are discussed above, and thus are not explained again here. After determining the operational mode of the RIS, in step s406, the controlling gNB informs the RIS the determined operational mode of the RIS. Then, in step s408, the RIS may configure / implement the determined operational mode.

[0065] Via the above embodiments, the RIS can be configured to properly cover the area of interest while severe interference to other networks is avoided. This, in turn, results in coverage extension and proper integration of the RISs into the existing networks.

[0066] FIG. 5 shows a process 500 performed by the RIS 102 according to some embodiments. As mentioned above, the RIS 102 is associated with the gNB 104 - i.e., a network node - operating on a first carrier frequency. The process 500 may begin with step s502. The step s502 comprises detecting an incoming signal which has a second carrier frequency. The step s502 corresponds to the step s202 of the process 200 shown in FIG. 2. Step s504 comprises determining whether the detected incoming signal is associated with the network node. The step s504 corresponds to the step s204 of the process 200 shown in FIG. 2. Step s506 comprises operating the RIS according to an operational mode of the RIS. The operational mode of the RIS is determined based at least on whether the detected incoming signal is associated with the network node, and the first and second carrier frequencies are the same or different.

[0067] In some embodiments, the operational mode of the RIS is determined based on any one or more of: a direction of receiving the incoming signal at the RIS; strength of the incoming signal received at the RIS; the first carrier frequency; and / or the second carrier frequency.

[0068] In some embodiments, the determined operational mode of the RIS is any one or a combination of: enabling a coherent reflecting functionality of the RIS; disabling the coherent reflecting functionality of the RIS; reducing the coherent reflection functionality of the RIS in terms of reflection angle and / or reflection power; disconnecting one or more antennas of the RIS from parts of circuitries of the RIS; enabling or disabling one or more parts of the RIS; and / or a specific configuration of the RIS.

[0069] In some embodiments, the specific configuration of the RIS is one of: setting one or more reflectorsof the RIS at a default reflection angle; setting said one or more reflectors of the RIS in a scattering mode; or setting said one or more reflectors of the RIS in an absorption mode.

[0070] In some embodiments, the default reflection angle is a reflection angle allowing that a signal reflected by the RIS at the reflection angle does not interfere with operations of user equipments, UEs, and / or network nodes, which are in proximity of the RIS.

[0071] In some embodiments, determining whether the detected incoming signal is associated with the network node comprises determining that the detected incoming signal is not associated with the network node, the operational mode of the RIS is determined based at least on that the detected incoming signal is not associated with the network node. The determined operational mode of the RIS is any one or a combination of: disabling the coherent reflecting functionality of the RIS; reducing the coherent reflection functionality of the RIS in terms of reflection angle and / or reflection power; disconnecting one or more antennas of the RIS from parts of circuitries of the RIS; disabling said one or more parts of the RIS; setting said one or more reflectors of the RIS in the scattering mode; and / or setting said one or more reflectors of the RIS in the absorption mode.

[0072] In some embodiments, the process 500 further comprises determining the operational mode of the RIS based at least on whether the detected incoming signal is associated with the network node.

[0073] In some embodiments, the process 500 further comprises after determining the operational mode of the RIS, transmitting, to the network node, a first message indicating the determined operational mode of the RIS.

[0074] In some embodiments, the first message transmitted to the network node comprises information about the detected incoming signal. The information about the detected incoming signal comprises any one or more of: a direction of receiving the incoming signal at the RIS; strength of the incoming signal received at the RIS; the second carrier frequency; and / or an indication of whether the detected incoming signal is associated with the network node.

[0075] In some embodiments, the process 500 further comprises receiving a second message from the network node in response to transmitting the first message to the network node. The second message indicates one or more of: whether the network node successfully received the first message, whether the network node agrees with the operational mode of the RIS, which is determined by the RIS, and / or one or more configurations of the RIS.

[0076] In some embodiments, the process 500 further comprises: determining a direction of receiving the incoming signal at the RIS, determining a direction of the network node with respect to the RIS, and comparing the direction of receiving the incoming signal to the direction of the network node with respect to the RIS. Determining whether the detected incoming signal is associated with the network node comprises determining that the detected incoming signal is not associated with the network node based at least on determining that the direction of receiving the incoming signal is different from the direction of the network node with respect to the RIS.

[0077] In some embodiments, the process 500 further comprises comparing the first carrier frequency to the second carrier frequency. Determining whether the detected incoming signal is associated with the network node comprises determining that the detected incoming signal is not associated with the network node based at least on determining that the first carrier frequency is different from the second carrier frequency.

[0078] In some embodiments, the process 500 further comprises transmitting, to the network node, a first message including information about the detected incoming signal. The information about the detected incoming signal comprises any one or more of: a direction receiving the incoming signal at the RIS; strength of the incoming signal received at the RIS; the second carrier frequency; an indication of whether the detected incoming signal is associated with the network node; and / or an indication of whether the operational mode of the RIS needs to be changed.

[0079] In some embodiments, the process 500 further comprises receiving, from the network node, a second message indicating the determined operational mode of the RIS.

[0080] In some embodiments, the process 500 further comprises configuring the operational mode of the RIS according to the received second message.

[0081] FIG. 6 shows a process 600 for operating the RIS 102, performed by the gNB 104 - i.e., a network node - according to some embodiments. As mentioned above, the RIS 102 is associated with the gNB 104 operating on a first carrier frequency. The process 600 may begin with step s602. The step s602 comprises receiving, from the RIS, a first message which includes information about an incoming signal detected at the RIS. The step s602 corresponds to the step s402 of the process 400 shown in FIG. 4. The incoming signal has a second carrier frequency, and the information about the detected incoming signal comprises an indication of whether the detected incoming signal is associated with the network node. Step s604 comprises, based at least on whether the detected incoming signal is associated with the network node, determining an operational mode of the RIS. The step s604 corresponds to the step s404 of the process 400 shown in FIG. 4. Step s606 comprises transmitting, to the RIS, a second message indicating the determined operational mode of the RIS. The step s606 corresponds to the step s406 of the process 400 shown in FIG. 4. The first and second carrier frequencies are the same or different.

[0082] In some embodiments, the information about the detected incoming signal comprises any one or more of: a direction of receiving the incoming signal at the RIS; strength of the incoming signal received at the RIS; and / or the second carrier frequency; an indication of whether the detected incoming signal is associated with the network node; and / or an indication of whether the operational mode of the RIS needs to be changed.

[0083] In some embodiments, the operational mode of the RIS is determined based on any one or more of: the direction of receiving the incoming signal at the RIS; the strength of the incoming signal received at the RIS; the first carrier frequency; and / or the second carrier frequency.

[0084] In some embodiments, the determined operational mode of the RIS is any one or a combination of: enabling a coherent reflecting functionality of the RIS; disabling the coherent reflecting functionality of the RIS; reducing the coherent reflection functionality of the RIS in terms of reflection angle and / or reflection power; disconnecting one or more antennas of the RIS from parts of circuitries of the RIS; enabling or disabling one or more parts of the RIS; and / or a specific configuration of the RIS.

[0085] In some embodiments, the specific configuration of the RIS is one of: setting one or more reflectors of the RIS at a default reflection angle; setting said one or more reflectors of the RIS in a scattering mode; or setting said one or more reflectors of the RIS in an absorption mode.

[0086] In some embodiments, the default reflection angle is a reflection angle allowing that a signal reflected by the RIS at the reflection angle does not interfere with operations of user equipments, UEs, and / or network nodes, which are in proximity of the RIS.

[0087] In some embodiments, the indication of whether the detected incoming signal is associated with the network node indicates that the detected incoming signal is not associated with the network node. The determined operational mode of the RIS is any one or a combination of: disabling the coherent reflecting functionality of the RIS; reducing the coherent reflection functionality of the RIS in terms of reflection angle and / or reflection power; disconnecting one or more antennas of the RIS from parts of circuitries of the RIS; disabling said one or more parts of the RIS; setting said one or more reflectors of the RIS in the scattering mode; and / or setting said one or more reflectors of the RIS in the absorption mode.

[0088] FIG. 7 shows a process 700 for operating the RIS 102, performed by the gNB 104 - i.e., a network node - according to some embodiments. As mentioned above, the RIS 102 is associated with the gNB 104. The process 700 may begin with step s702. The step s702 comprises receiving, from the RIS, a first message indicating an operational mode of the RIS. Step s704 comprises determining whether the indicated operational mode of the RIS is acceptable or not. Step s706 comprises, based at least on the determination, transmitting, to the RIS, a second message indicating whether the indicated operational mode of the RIS is acceptable or not.

[0089] In some embodiments, the indicated operational mode of the RIS is any one or a combination of: enabling a coherent reflecting functionality of the RIS; disabling the coherent reflecting functionality of the RIS; reducing the coherent reflection functionality of the RIS in terms of reflection angle and / or reflection power; disconnecting one or more antennas of the RIS from parts of circuitries of the RIS; enabling or disabling one or more parts of the RIS; and / or a specific configuration of the RIS.

[0090] In some embodiments, the specific configuration of the RIS is one of: setting one or more reflectors of the RIS at a default reflection angle; setting said one or more reflectors of the RIS in a scattering mode; or settingsaid one or more reflectors of the RIS in an absorption mode.

[0091] In some embodiments, the first message comprises information about an incoming signal detected at the RIS. The information about the incoming signal comprises any one or more of: a direction of receiving the incoming signal at the RIS; strength of the incoming signal received at the RIS; a carrier frequency of the incoming signal; and / or an indication of whether the incoming signal is associated with the network node.

[0092] In some embodiments, whether the indicated operational mode of the RIS is acceptable or not is determined by the network node based on the information about the incoming signal detected at the RIS.

[0093] In some embodiments, determining whether the indicated operational mode of the RIS is acceptable or not comprises determining that the indicated operational mode of the RIS is not acceptable. The process 700 further comprises, as a result of determining that the indicated operational mode of the RIS is not acceptable, determining a different operational mode of the RIS which is different from the indicated operational mode of the RIS. The different operational mode of the RIS is determined based on the information about the incoming signal detected at the RIS, and the second message indicates the different operational mode of the RIS.

[0094] FIG. 8 is a block diagram of a network node 800 which can be used to implement the RIS 102, according to some embodiments. As shown in FIG. 8, network node 800 may comprise: processing circuitry (PC) 802, which comprises one or more processors (P) 855 (e.g., one or more general purpose microprocessors and / or one or more other processors, such as an application specific integrated circuit (ASIC), field -programmable gate arrays (FPGAs), and the like), which processors may be co-located in a single housing or in a single data center or may be geographically distributed (e.g., network node 800 may be a distributed computing apparatus comprising two or more computers or a monolithic computing apparatus consisting of a single computer); at least one network interface 848 (e.g., a physical interface or air interface) comprising a transmitter (Tx) 845 and a receiver (Rx) 847 for enabling network node 800 to transmit data to and receive data from other nodes connected to network 110 (e.g., an Internet Protocol (IP) network) to which network interface 848 is connected (physically or wirelessly) (e.g., network interface 848 may be coupled to an antenna arrangement comprising one or more antennas for enabling network node 800 to wirelessly transmit / receive data); and a storage unit (a.k.a., "data storage system”) 808, which may include one or more non-volatile storage devices and / or one or more volatile storage devices. In embodiments where PC 802 includes a programmable processor, a computer readable storage medium (CRSM) 842 may be provided. CRSM 842 may store a computer program (CP) 843 comprising computer readable instructions (CRI) 844. CRSM 842 may be a non-transitory computer readable medium, such as, magnetic media (e.g., a hard disk), optical media, memory devices (e.g., random access memory, flash memory), and the like. In some embodiments, the CRI 844 of computer program 843 is configured such that when executed by PC 802, the CRI causes network node 800 to perform steps described herein (e.g., steps described herein with reference to the flow charts). In otherembodiments, network node 800 may be configured to perform steps described herein without the need for code. That is, for example, PC 802 may consist merely of one or more ASICs. Hence, the features of the embodiments described herein may be implemented in hardware and / or software.

[0095] FIG. 9 is a block diagram of the gNB 104, according to some embodiments for performing the base station methods disclosed herein. As shown in FIG. 9, the gNB 104 may comprise: processing circuitry (PC) 902, which comprises one or more processors (P) 955 (e.g., a general purpose microprocessor and / or one or more other processors, such as an application specific integrated circuit (ASIC), field-programmable gate arrays (FPGAs), and the like), which processors may be co-located in a single housing or in a single data center or may be geographically distributed (i.e., base station may be a distributed computing apparatus or a monolithic computing apparatus); a network interface 968 comprising a transmitter (Tx) 965 and a receiver (Rx) 967 for enabling the gNB 104 to transmit data to and receive data from other nodes connected to a network 110 (e.g., an Internet Protocol (IP) network) to which network interface 968 is connected; communication circuitry 948 (e.g., radio transceiver circuitry comprising an Rx 947 and a Tx 945) coupled to an antenna system 949 for wireless communication with UEs or other nodes; and a storage unit (a.k.a., "data storage system”) 908, which may include one or more non-volatile storage devices and / or one or more volatile storage devices. In embodiments where PC 902 includes a programmable processor, a computer readable storage medium (CRSM) 942 may be provided. CRSM 942 may store a computer program (CP) 943 comprising computer readable instructions (CRI) 944. CRSM 942 may be a non-transitory computer readable medium, such as, magnetic media (e.g., a hard disk), optical media, memory devices (e.g., random access memory, flash memory), and the like. In some embodiments, the CRI 944 of computer program 943 is configured such that when executed by PC 902, the CRI causes the gNB 104 to perform steps described herein (e.g., steps described herein with reference to one or more flow charts). In other embodiments, the gNB 104 may be configured to perform steps described herein without the need for code. That is, for example, PC 902 may consist merely of one or more ASICs. Hence, the features of the embodiments described herein may be implemented in hardware and / or software.

[0096] Summary of Embodiments

[0097] While various embodiments are described herein, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of this disclosure should not be limited by any of the above-described exemplary embodiments. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the disclosure unless otherwise indicated herein or otherwise clearly contradicted by context.

[0098] As used herein transmitting a message "to” or "toward” an intended recipient encompasses transmitting the message directly to the intended recipient or transmitting the message indirectly to the intended recipient (i.e. , one or more other nodes are used to relay the message from the source node to the intended recipient). Likewise, as used herein receiving a message "from” a sender encompasses receiving the message directly from the sender or indirectly from the sender (i.e., one or more nodes are used to relay the message from the sender to the receiving node). Further, as used herein "a” means "at least one” or "one or more.”

[0099] Additionally, while the processes described above and illustrated in the drawings are shown as a sequence of steps, this was done solely for the sake of illustration. Accordingly, it is contemplated that some steps may be added, some steps may be omitted, the order of the steps may be re-arranged, and some steps may be performed in parallel.

Claims

CLAIMS1. A method (500) for operating a reconfigurable intelligent surface (RIS) (102) which is associated with a network node (104) operating on a first carrier frequency, the method being performed by the RIS, the method comprising: detecting (s502) an incoming signal which has a second carrier frequency; determining (s504) whether the detected incoming signal is associated with the network node; and operating (s506) the RIS according to an operational mode of the RIS, wherein the operational mode of the RIS is determined based at least on whether the detected incoming signal is associated with the network node, and the first and second carrier frequencies are the same or different.

2. The method of claim 1, wherein the operational mode of the RIS is determined based on any one or more of: a direction of receiving the incoming signal at the RIS; strength of the incoming signal received at the RIS; the first carrier frequency; and / or the second carrier frequency.

3. The method of claim 1 or 2, wherein the determined operational mode of the RIS is any one or a combination of: enabling a coherent reflecting functionality of the RIS; disabling the coherent reflecting functionality of the RIS; reducing the coherent reflection functionality of the RIS in terms of reflection angle and / or reflection power; disconnecting one or more antennas of the RIS from parts of circuitries of the RIS; enabling or disabling one or more parts of the RIS; and / or a specific configuration of the RIS.

4. The method of claim 3, wherein the specific configuration of the RIS is one of: setting one or more reflectors of the RIS at a default reflection angle; setting said one or more reflectors of the RIS in a scattering mode; or setting said one or more reflectors of the RIS in an absorption mode.

5. The method of claim 4, wherein the default reflection angle is a reflection angle allowing that a signal reflected by the RIS at the reflection angle does not interfere with operations of user equipments, UEs, and / or network nodes, which are in proximity of the RIS.

6. The method of claim 4 or 5, wherein determining whether the detected incoming signal is associated with the network node comprises determining that the detected incoming signal is not associated with the network node, the operational mode of the RIS is determined based at least on that the detected incoming signal is not associated with the network node, and the determined operational mode of the RIS is any one or a combination of: disabling the coherent reflecting functionality of the RIS; reducing the coherent reflection functionality of the RIS in terms of reflection angle and / or reflection power; disconnecting one or more antennas of the RIS from parts of circuitries of the RIS; disabling said one or more parts of the RIS; setting said one or more reflectors of the RIS in the scattering mode; and / or setting said one or more reflectors of the RIS in the absorption mode.

7. The method of any one of claims 1-6, wherein the method further comprises: determining the operational mode of the RIS based at least on whether the detected incoming signal is associated with the network node.

8. The method of claim 7, wherein the method further comprises: after determining the operational mode of the RIS, transmitting, to the network node, a first message indicating the determined operational mode of the RIS.

9. The method of claim 8, wherein the first message transmitted to the network node comprises information about the detected incoming signal, and the information about the detected incoming signal comprises any one or more of: a direction of receiving the incoming signal at the RIS; strength of the incoming signal received at the RIS; the second carrier frequency; and / or an indication of whether the detected incoming signal is associated with the network node.

10. The method of claim 8 or 9, wherein the method further comprises receiving a second message from the network node in response to transmitting the first message to the network node, and the second message indicates one or more of: whether the network node successfully received the first message, whether the network node agrees with the operational mode of the RIS, which is determined by the RIS, and / or one or more configurations of the RIS.11 . The method of any one of claims 7-10, wherein the method further comprises: determining a direction of receiving the incoming signal at the RIS, determining a direction of the network node with respect to the RIS, and comparing the direction of receiving the incoming signal to the direction of the network node with respect to the RIS, and determining whether the detected incoming signal is associated with the network node comprises determining that the detected incoming signal is not associated with the network node based at least on determining that the direction of receiving the incoming signal is different from the direction of the network node with respect to the RIS.

12. The method of any one of claims 7-11, wherein the method further comprises comparing the first carrier frequency to the second carrier frequency, and determining whether the detected incoming signal is associated with the network node comprises determining that the detected incoming signal is not associated with the network node based at least on determining that the first carrier frequency is different from the second carrier frequency.

13. The method of any one of claims 1-5, wherein the method further comprises transmitting, to the network node, a first message including information about the detected incoming signal, and the information about the detected incoming signal comprises any one or more of: a direction receiving the incoming signal at the RIS; strength of the incoming signal received at the RIS; the second carrier frequency;an indication of whether the detected incoming signal is associated with the network node; and / or an indication of whether the operational mode of the RIS needs to be changed.

14. The method of claim 13, wherein the method further comprises: receiving, from the network node, a second message indicating the determined operational mode of the RIS.

15. The method of claim 13 or 14, wherein the method further comprises: configuring the operational mode of the RIS according to the received second message.

16. A method (600) for operating a reconfigurable intelligent surface (RIS) (102) which is associated with a network node (104) operating on a first carrier frequency, the method being performed by the network node, the method comprising: receiving (s602), from the RIS, a first message which includes information about an incoming signal detected at the RIS, wherein the incoming signal has a second carrier frequency, and further wherein the information about the detected incoming signal comprises an indication of whether the detected incoming signal is associated with the network node; based at least on whether the detected incoming signal is associated with the network node, determining (s604) an operational mode of the RIS; and transmitting (s606), to the RIS, a second message indicating the determined operational mode of the RIS, wherein the first and second carrier frequencies are the same or different.

17. The method of claim 16, wherein the information about the detected incoming signal comprises any one or more of: a direction of receiving the incoming signal at the RIS; strength of the incoming signal received at the RIS; and / or the second carrier frequency; an indication of whether the detected incoming signal is associated with the network node; and / or an indication of whether the operational mode of the RIS needs to be changed.

18. The method of claim 17, wherein the operational mode of the RIS is determined based on any one or more of:the direction of receiving the incoming signal at the RIS; the strength of the incoming signal received at the RIS; the first carrier frequency; and / or the second carrier frequency.

19. The method of any one of claims 16-18, wherein the determined operational mode of the RIS is any one or a combination of: enabling a coherent reflecting functionality of the RIS; disabling the coherent reflecting functionality of the RIS; reducing the coherent reflection functionality of the RIS in terms of reflection angle and / or reflection power; disconnecting one or more antennas of the RIS from parts of circuitries of the RIS; enabling or disabling one or more parts of the RIS; and / or a specific configuration of the RIS.

20. The method of claim 19, wherein the specific configuration of the RIS is one of: setting one or more reflectors of the RIS at a default reflection angle; setting said one or more reflectors of the RIS in a scattering mode; or setting said one or more reflectors of the RIS in an absorption mode.21 . The method of claim 20, wherein the default reflection angle is a reflection angle allowing that a signal reflected by the RIS at the reflection angle does not interfere with operations of user equipments, UEs, and / or network nodes, which are in proximity of the RIS.

22. The method of claim 20 or 21 , wherein the indication of whether the detected incoming signal is associated with the network node indicates that the detected incoming signal is not associated with the network node, and the determined operational mode of the RIS is any one or a combination of: disabling the coherent reflecting functionality of the RIS; reducing the coherent reflection functionality of the RIS in terms of reflection angle and / or reflection power; disconnecting one or more antennas of the RIS from parts of circuitries of the RIS; disabling said one or more parts of the RIS; setting said one or more reflectors of the RIS in the scattering mode; and / or setting said one or more reflectors of the RIS in the absorption mode.

23. A method (700) for operating a reconfigurable intelligent surface (RIS) (102) which is associated with a network node (104), the method being performed by the network node, the method comprising: receiving (s702), from the RIS, a first message indicating an operational mode of the RIS; determining (s704) whether the indicated operational mode of the RIS is acceptable or not; and based at least on the determination, transmitting (s706), to the RIS, a second message indicating whether the indicated operational mode of the RIS is acceptable or not.

24. The method of claim 23, wherein the indicated operational mode of the RIS is any one or a combination of: enabling a coherent reflecting functionality of the RIS; disabling the coherent reflecting functionality of the RIS; reducing the coherent reflection functionality of the RIS in terms of reflection angle and / or reflection power; disconnecting one or more antennas of the RIS from parts of circuitries of the RIS; enabling or disabling one or more parts of the RIS; and / or a specific configuration of the RIS.

25. The method of claim 24, wherein the specific configuration of the RIS is one of: setting one or more reflectors of the RIS at a default reflection angle; setting said one or more reflectors of the RIS in a scattering mode; or setting said one or more reflectors of the RIS in an absorption mode.

26. The method of any one of claims 23-25, wherein the first message comprises information about an incoming signal detected at the RIS, and the information about the incoming signal comprises any one or more of: a direction of receiving the incoming signal at the RIS; strength of the incoming signal received at the RIS; a carrier frequency of the incoming signal; and / or an indication of whether the incoming signal is associated with the network node.

27. The method of claim 26, wherein whether the indicated operational mode of the RIS is acceptable or not is determined by the network node based on the information about the incoming signal detected at the RIS.

28. The method of claim 26 or 27, whereindetermining whether the indicated operational mode of the RIS is acceptable or not comprises determining that the indicated operational mode of the RIS is not acceptable, the method further comprises, as a result of determining that the indicated operational mode of the RIS is not acceptable, determining a different operational mode of the RIS which is different from the indicated operational mode of the RIS, the different operational mode of the RIS is determined based on the information about the incoming signal detected at the RIS, and the second message indicates the different operational mode of the RIS.

29. A computer program (800 or 800) comprising instructions (844 or 944) which when executed by processing circuitry (802 or 902) cause the processing circuitry to perform the method of any one of claims 1-28.

30. A carrier containing the computer program of claim 29, wherein the carrier is one of an electronic signal, an optical signal, a radio signal, and a computer readable storage medium.

31. A reconfigurable intelligent surface (RIS) (102) which is associated with a network node (104) operating on a first carrier frequency, the RIS being configured to: detect (s502) an incoming signal which has a second carrier frequency; determine (s504) whether the detected incoming signal is associated with the network node; and operate (s506) according to an operational mode of the RIS, wherein the operational mode of the RIS is determined based at least on whether the detected incoming signal is associated with the network node, and the first and second carrier frequencies are the same or different.

32. The RIS of claim 31 , wherein the RIS is configured to perform the method of any one of claims 2-15.

33. A network node (104) for operating a reconfigurable intelligent surface (RIS) (102) which is associated with the network node, the network node operating on a first carrier frequency, the network node being configured to: receive (s602), from the RIS, a first message which includes information about an incoming signal detected at the RIS, wherein the incoming signal has a second carrier frequency, and further wherein the information about the detected incoming signal comprises an indication of whether the detected incoming signal is associated with the network node; based at least on whether the detected incoming signal is associated with the network node, determine (s604) an operational mode of the RIS; andtransmit (s606), to the RIS, a second message indicating the determined operational mode of the RIS, wherein the first and second carrier frequencies are the same or different.

34. The network node of claim 33, wherein the network node is configured to perform the method of any one of claims 17-22.

35. A network node (104) for operating a reconfigurable intelligent surface (RIS) (102) which is associated with the network node, the network node being configured to: receive (s702), from the RIS, a first message indicating an operational mode of the RIS; determine (s704) whether the indicated operational mode of the RIS is acceptable or not; and based at least on the determination, transmit (s706), to the RIS, a second message indicating whether the indicated operational mode of the RIS is acceptable or not.

36. The network node of claim 35, wherein the network node is configured to perform the method of any one of claims 24-28.

37. An apparatus (800 or 900) comprising: processing circuitry (802 or 902); and a memory (841 or 941), said memory containing instructions executable by said processing circuitry, whereby the apparatus is operative to perform the method of any one of claims 1-28.

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