Handling link failures between reflective nodes and network nodes

Abstract

A reflector node for handling a link failure toward a network node is provided. The reflector node includes a controller for controlling a passive meta-surface having a controllable reflection angle, the passive meta-surface being configured to reflect radio waves on a communication channel between the network node and a wireless device. The reflector node includes a transceiver unit for receiving instructions from the network node over a control channel. The transceiver unit is configured to determine a link failure event on the control channel between the reflector node and the network node. The controller is configured to control the reflection angle of the passive meta-surface for reflecting radio waves on the communication channel during the link failure event using a reflection setting specified by configuration data.

Description

Technical Field

[0001] The embodiments presented herein relate to a method, a reflector node, a computer program and a computer program product for handling a link failure towards a network node. The embodiments presented herein also relate to a method, a network node, a computer program and a computer program product for handling a link failure towards a reflector node. Background Art

[0002] For new radio (NW) air interfaces such as those used in fifth generation (5G) telecommunication systems, millimeter waves (mmWaves) corresponding to carrier frequencies above 10 GHz have been introduced. However, communication via mmWaves is sensitive to obstruction, i.e., physical objects blocking the radio waves. Reference will now be made to Figure 1 Non-limiting examples of blocking and its effects are disclosed. Figure 1 An example of a communication network 100a is shown. Communication network 100a includes two network nodes 300a and 300b (e.g., provided as (radio) access network nodes) configured to provide network access to wireless devices, one of which is shown with reference numeral 400a. The network node physically closest to wireless device 400a is network node 300a. However, the signal path between network node 300a and wireless device 400a, corresponding to communication channel 120a, is blocked by a first physical object 110a. Furthermore, possible non-line-of-sight signal paths from network node 300a, one of which corresponds to communication channel 120b, do not reach wireless device 400a due to signal reflections from physical object 110b. This results in wireless device 400a being operatively connected instead to network node 300b, which has a line-of-sight signal path corresponding to communication channel 120c. Since the physical distance from the network node 300b to the wireless device 400a is longer than the physical distance from the network node 300a to the wireless device 400a, the network node 300b has a larger path loss.

[0003] One technique that can create a smart radio environment involves using surfaces that can interact with the radio environment.

[0004] For example, as reported in “Smart Radio Environments Empowered by AI Reconfigurable Meta-Surfaces: An Idea Whose Time Has Come” by Marco Di Renzo et al., available at https: / / arxiv.org / abs / 1903.08925 (last accessed September 20, 2020), “Reconfigurable-Intelligent-Surface Empowered Wireless Communations: Challenges and Opportunities” by Xiaojun Yuan et al., available at https: / / arxiv.org / abs / 2001.00364 (last accessed September 20, 2020), and in the November 2019 IEEE Transactions on Wireless Communications. As disclosed in “Intelligent Reflecting Surface Enhanced Wireless Network via Joint Active and Passive Beamforming” by Q. Wu and R. Zhang in “IEEE Communications, Vol. 18, No. 11, pp. 5394-5409, doi:10.1109 / TWC.2019.2936025,” such surfaces are generally referred to as metasurfaces, reconfigurable smart surfaces, large-scale smart surfaces, or smart reconfigurable surfaces. Without losing the generality or distinction of these terms, the term metasurface will be used throughout this disclosure.

[0005] Metasurfaces are electromagnetic surfaces made of electromagnetic materials that have been carefully designed to exhibit properties not found in naturally occurring materials. In practice, a metasurface is an electromagnetic discontinuity, which can be defined as a complex electromagnetic structure that is typically deeply sub-wavelength in thickness, electrically large in lateral dimensions, and includes sub-wavelength scattering particles with extremely small features. In simple terms, a metasurface consists of a two-dimensional array of sub-wavelength metallic or dielectric scattering particles that convert incident electromagnetic waves in different ways, causing the electromagnetic wave to be reflected depending on the structure of the metasurface.

[0006] In more detail, a passive metasurface is a metasurface in which the scattering particles or electromagnetic reflection properties are not fixed and designed during the manufacturing phase, but can be modified according to an external stimulus provided to the metasurface. In the present disclosure, the external stimulus is defined by a control signal from a reflection node. In one example, the passive metasurface includes an array of passive patch antennas. That is, the antennas are not connected to an active radio transceiver (i.e., a device capable of modulating a data stream to a radio frequency and demodulating the radio frequency to a data stream). Instead, the antennas in the array are connected to resistors, inductors and / or capacitors with controllable electrical impedance, and wherein the antennas are connected to resistors, inductors and / or capacitors facing the ground plane so that the reflection phase of the corresponding antenna can be adapted based on the electrical impedance setting. Therefore, by controlling the electrical impedance of the corresponding patch antenna, the reflection angle of the incident electromagnetic wave can be adapted according to the generalized Snell's law.

[0007] Thus, one difference between a regular surface and a passive metasurface is the ability of a passive metasurface to shape or reflect incident electromagnetic waves (e.g., radio waves) according to the generalized Snell's law of reflection and refraction. For example, the angle of incidence and the angle of reflection of a radio wave are not necessarily the same in a passive metasurface. Therefore, returning to reference Figure 1 For example, if the object 110b is provided with a passive meta-surface, the reflection of the signal via the physical object 110b can be controlled by the physical object 110b provided with the passive meta-surface so that the signal can indeed reach the wireless device 400a. Figure 2 Shown in. Figure 2 Communication network 100b is shown having the same components as communication network 100a, but a reflective node 200 having a passive metasurface 250 is provided at physical object 110b so that signals from network node 300a reach wireless device 400a via a non-line-of-sight signal path corresponding to communication channel 120b.

[0008] Generally speaking, the reflection node 200 is configured to control the reflection angle of the passive element surface. To do so, a separate control channel is established between the network node 300a and the reflection node 200. This control channel is typically established wirelessly using any known cellular communication technology using a carrier frequency below 6 GHz or any local wireless area network standard (e.g., Wi-Fi) or other radio access technology used in the unlicensed radio spectrum. However, the control channel can also be established via a wired medium (e.g., fiber optic cable).

[0009] However, there is a risk that interference may occur on the control channel between network node 300a and reflection node 200 while communication between network node 300a and wireless device 400a via the passive meta-surface is still running (e.g., using another communication technology, frequency band, etc.). Due to the interference on the control channel, network node 300a may no longer be able to instruct reflection node 200 on how to control the reflection angle of the passive meta-surface. This, in turn, may result in communication channel 120b being dropped.

[0010] Therefore, a mechanism is needed to handle link failures between network nodes and reflective nodes. Summary of the Invention

[0011] One object of the embodiments herein is to provide a mechanism for handling link failures between a network node and a reflection node, so that the above-mentioned problems can be avoided or at least alleviated or reduced.

[0012] According to a first aspect, a reflector node for handling a link failure toward a network node is provided. The reflector node includes a controller for controlling a passive meta-surface having a controllable reflection angle, the passive meta-surface being configured to reflect radio waves on a communication channel between the network node and a wireless device. The reflector node includes a transceiver unit for receiving instructions from the network node on a control channel. The transceiver unit is configured to determine a link failure event on the control channel between the reflector node and the network node. The controller is configured to control the reflection angle of the passive meta-surface for reflecting the radio waves on the communication channel during the link failure event using a reflection setting specified by configuration data.

[0013] According to a second aspect, a method for handling a link failure toward a network node is provided. The method is performed by a reflector node. The reflector node includes a passive metasurface having a controllable reflection angle, the passive metasurface configured to reflect radio waves on a communication channel between the network node and a wireless device. The reflector node receives instructions from the network node over a control channel. The method includes determining a link failure event on the control channel between the reflector node and the network node. In response thereto, the method includes controlling a reflection angle of the passive metasurface for reflecting the radio waves on the communication channel during the link failure event using a reflection setting specified by configuration data.

[0014] According to a third aspect, a computer program for handling a link failure towards a network node is proposed, the computer program comprising computer program code which, when executed on a processing circuit of a reflection node, causes the reflection node to perform the method according to the second aspect.

[0015] According to a fourth aspect, a network node for handling a link failure toward a reflector node is provided. The network node includes a communication interface for sending instructions to the reflector node over a control channel and for communicating with at least one wireless device over a communication channel using radio waves. The radio waves are reflected at a reflection angle at a passive element surface of the reflector node between the network node and the wireless device. The network node includes processing circuitry configured to determine a link failure event on the control channel between the network node and the reflector node. The processing circuitry is configured to control the communication interface for communicating with the wireless device according to configuration data during the link failure event. The configuration data specifies reflection settings, according to which the reflection angle at the passive element surface of the reflector node is controlled during the link failure event.

[0016] According to a fifth aspect, a method for handling a link failure toward a reflector node is provided. The method is performed by a network node. The network node sends instructions to the reflector node over a control channel. The network node communicates with at least one wireless device over a communication channel using radio waves. The radio waves are reflected at a reflection angle at a passive element surface of the reflector node between the network node and the wireless device. The method includes determining a link failure event on the control channel between the network node and the reflector node. In response thereto, the method includes communicating with the wireless device according to configuration data during the link failure event. The configuration data specifies reflection settings, and according to the reflection settings, the reflection angle at the passive element surface of the reflector node is controlled during the link failure event.

[0017] According to a sixth aspect, a computer program for handling a link failure towards a reflective node is proposed, the computer program comprising computer program code which, when executed on a processing circuit of a network node, causes the network node to perform the method according to the fifth aspect.

[0018] According to a seventh aspect, a computer program product is provided, comprising a computer program according to at least one of the third and sixth aspects and a computer-readable storage medium on which the computer program is stored. The computer-readable storage medium may be a non-transitory computer-readable storage medium.

[0019] Advantageously, the reflection node, the network node, the methods, the computer programs and the computer program product enable handling of link failures between a network node and a reflection node, thereby avoiding the above-mentioned problems.

[0020] Advantageously, by enabling well-defined behavior of how the reflecting node controls the reflection angle if the control channel between the network node and the reflecting node drops, both the network node and the reflecting node still know how the reflecting node will behave.

[0021] This, in turn, improves the chances of maintaining a connection between the network node and the wireless device it serves in situations where signals between the network node and the wireless device are reflected by the passive meta-surface controlled by the reflecting node.

[0022] This, in turn, increases system capacity and user experience.

[0023] Other objectives, features and advantages of the accompanying embodiments will be apparent from the following detailed disclosure, from the attached dependent claims as well as from the drawings.

[0024] Generally, all terms used in the claims should be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. Unless explicitly stated otherwise, all references to "a / an / the element, device, component, means, module, step, etc." should be interpreted openly as referring to at least one instance of the element, device, component, means, module, step, etc. Unless explicitly stated otherwise, the steps of any method disclosed herein do not have to be performed in the exact order disclosed. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will now be described by way of example with reference to the accompanying drawings, in which:

[0026] Figure 1 、 2 3 are schematic diagrams showing a communication network according to an embodiment;

[0027] Figure 4 is a block diagram of a reflective node according to an embodiment;

[0028] Figure 5 and 6 is a flow chart of a method according to an embodiment;

[0029] Figure 7 is a schematic diagram illustrating functional units of a reflective node according to an embodiment;

[0030] Figure 8 is a schematic diagram illustrating functional modules of a reflective node according to an embodiment;

[0031] Figure 9 is a schematic diagram illustrating functional units of a network node according to an embodiment;

[0032] Figure 10is a schematic diagram illustrating functional modules of a network node according to an embodiment; and

[0033] Figure 11 One example of a computer program product comprising computer readable means according to an embodiment is shown. DETAILED DESCRIPTION

[0034] The present invention will now be described more fully below with reference to the accompanying drawings, in which certain embodiments of the present invention are shown. However, the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete and will fully convey the scope of the present invention to those skilled in the art. Throughout the description, like numbers refer to like elements. Any steps or features shown in dashed lines should be considered optional.

[0035] As mentioned above, a mechanism is needed to handle link failures between network nodes and reflection nodes. Therefore, one object of embodiments herein is to provide a mechanism for handling link failures between network nodes and reflection nodes, so that the above problems can be avoided or at least alleviated or reduced.

[0036] Therefore, embodiments disclosed herein relate to mechanisms for handling link failures towards network nodes 300a, 300b and for handling link failures towards the reflection node 200. To achieve such mechanisms, a reflection node 200, a method performed by the reflection node 200, and a computer program product comprising code, e.g., in the form of a computer program, which, when executed on a processing circuit of the reflection node 200, causes the reflection node 200 to perform the method are provided. To achieve such mechanisms, a network node 300a, 300b, a method performed by the network node 300a, 300b, and a computer program product comprising code, e.g., in the form of a computer program, which, when executed on a processing circuit of the network node 300a, 300b, causes the network node 300a, 300b to perform the method are further provided.

[0037] Now we will refer to Figure 3 and Figure 4 An embodiment of a reflective node 200 for handling link failures towards network nodes 300a, 300b is disclosed. Figure 3A communication network 100c is shown having the same components as the communication network 100b, but without the network node 300b, and the network node 300a serves two wireless devices 400a, 400b, and wherein the reflection node 200 is configured according to the embodiments disclosed herein. Each wireless device 400a, 400b may be any one of a portable wireless device, a mobile station, a mobile phone, a handset, a wireless local loop phone, a user equipment (UE), a smart phone, a wearable communication device, a laptop computer, a tablet computer, a wireless modem, a wireless sensor device, a network-equipped vehicle, an Internet of Things (IoT) device. Figure 3 In the embodiment, network node 300a communicates with wireless devices 400a and 400b via reflection node 200 on communication channels 120a and 120d at respective different times (T1 and T2) in a first frequency interval (f1), while network node 300a communicates with reflection node 200 on control channel 130 in a second frequency interval (f2). Although control channel 130 is shown as being established over a wireless link, control channel 130 can be established over a wired link between network node 300a and reflection node 200. Network node 300a is thereby able to control the reflection angle of the passive element surface at reflection node 200 so that communication between network node 300a and wireless device 400a can be maintained on communication channel 120a in the first frequency interval f1 during time T1, and communication with wireless device 400b can be maintained on communication channel 120d in the first frequency interval f1 during time T2. The first frequency interval f1 may be a mmW frequency interval, and the second frequency interval f2 may be a frequency interval below 6 GHz or at least a frequency interval that does not overlap with the first frequency interval. Figure 4 is a block diagram of a reflection node 200 according to an embodiment.

[0038] The reflective node 200 comprises a controller 260 for controlling a passive metasurface 250 having a controllable reflection angle for reflecting radio waves on the communication channels 120a, 120d between the network node 300a and the wireless devices 400a, 400b.

[0039] The reflex node 200 comprises a transceiver unit 270 for receiving instructions from the network node 300a on the control channel 130 .

[0040] The transceiver unit 270 is configured to determine a link failure event on the control channel 130 between the reflection node 200 and the network node 300a.

[0041] The controller 260 is configured to control the reflection angle of the passive meta-surface 250 for reflecting radio waves on the communication channels 120a: 120d during a link failure event using the reflection settings specified by the configuration data.

[0042] Advantageously, by enabling well-defined behavior for how the reflecting node 200 controls the reflection angle in the event that the control channel 130 between the network node 300a and the reflecting node 200 goes offline, both the network node 300a and the reflecting node 200 still know how the reflecting node 200 will behave. This, in turn, improves the chances of maintaining connectivity between the network node 300a and the wireless devices 400a, 400b it serves in the event that signals between the network node 300a and the wireless devices 400a, 400b are reflected by the passive meta-surface 250 controlled by the reflecting node 200. This, in turn, results in increased system capacity and user experience.

[0043] Embodiments involving more details of the reflection node 200 will now be disclosed.

[0044] There may be different examples of configuration data, and three embodiments related thereto will now be disclosed in sequence.

[0045] According to a first embodiment, the reflection angle used immediately before a link failure event is determined is retained based on configuration data. In this regard, while a link failure is ongoing, the reflection angle may change by at least one value. For example, the reflection angle may change at a time point defined by a timer. Thus, the reflection angle may be retained until the timer expires, after which one or more different reflection angles may be used. Specifically, based on configuration data, the reflection angle used immediately before a link failure event is determined may only be retained until the timer started when the link failure event is determined expires. Various methods can be used to determine the timer value, i.e., the duration from timer initiation to timer expiration. In some examples, the timer is aligned with the link reestablishment process. Specifically, in some aspects, after a link failure event is determined, a reestablishment process is initiated between reflector node 200 and network node 300a. The reestablishment process takes place within a maximum time period, and the timer may have an expiration time equal to this time period. If the timer expires before the link failure is resolved, various methods may be used to determine the reflection angle. In some examples, the reflection angle uses a value defined by a default setting. Specifically, in some aspects, when a link failure event is still ongoing after the timer expires, the reflection angle is defined by the default setting based on configuration data.

[0046] According to the second embodiment, the reflection angle is defined by a default reflection setting according to the configuration data. Thus, when a link failure event has been detected, the default reflection setting can be directly applied without requiring the reflective node 200 to first maintain the reflection angle used immediately before the link failure event was determined.

[0047] According to a third embodiment, the reflection angle may be changed according to a set of reflection settings based on configuration data. The set of reflection settings may include the reflection angle used immediately before a link failure event was determined and one or more default reflection settings. Furthermore, according to the configuration data, the reflection angle may be periodically changed between the reflection settings in the set of reflection settings. For example, the reflection angle may be periodically changed based on time information (e.g., provided by a timestamp). In particular, the configuration data may include a timestamp, wherein the timestamp defines how the reflection angle changes over time between the reflection settings in the set of reflection settings. Furthermore, in some examples, the timestamp defines when broadcast symbols will be sent and when unicast symbols will be sent. That is, in some aspects, broadcast symbols and unicast symbols are sent on communication channels 120a:120d between network node 300a and wireless devices 400a, 400b, and the timestamps are defined by when the broadcast symbols will be sent and when the unicast symbols will be sent. In a further example, the timestamps are replaced by triggers provided by one or more timers, such that when the timers expire, this triggers the reflection angle to be changed. That is, when the first timer expires, this triggers the first change in the reflection angle (to a value). Then, when the second timer expires, this triggers the reflection angle to change a second time (to another value), and so on. Thus, the timer can be used to sequentially change the reflection angle from one value to the next. In a further example, a default setting is used for broadcast symbols, while the last used setting is retained for unicast symbols. That is, in some aspects, according to the configuration data, the reflection angle is defined by the first setting when broadcast symbols are transmitted, while the reflection angle is defined by the second setting when unicast symbols are transmitted. Furthermore, in some examples, the first setting is the default reflection setting, while according to the second setting, the reflection angle used immediately before the link failure event is determined is used when transmitting broadcast symbols.

[0048] Aspects of the passive meta-surface 250 and how its reflection angle can be controlled will now be disclosed. In some embodiments, the passive meta-surface 250 includes at least two passive meta-surface portions. Based on configuration data, the reflection angle for each of the at least two passive meta-surface portions may be different. Thus, one state may be applied to one sub-surface of the passive meta-surface 250, while another state is simultaneously applied to another sub-surface of the passive meta-surface 250, with each state corresponding to a particular reflection angle or a set of reflection angles applied sequentially. In other words, the passive meta-surface 250 may simultaneously have two or more reflection angles. For example, a sub-surface of the passive meta-surface 250 used to reflect broadcast signals may be configured according to one state, while another sub-surface of the passive meta-surface 250 used to reflect unicast signals may be configured according to another state. Alternatively or additionally, two or more sub-surfaces may share a state for one symbol but may be configured to have separate states for another symbol. Thus, each of the at least two passive meta-surface portions may have a first setting and a second setting.

[0049] Furthermore, in accordance with the above, the reflective node 200 and the passive meta-surface 250 are arranged relative to at least one another such that the controller 260 of the reflective node 200 is configured to control the reflection angle of the passive meta-surface 250 during a link failure event. In some aspects, the passive meta-surface 250 is part of the reflective node 200. That is, in some embodiments, the reflective node 200 also includes the passive meta-surface 250.

[0050] There are different ways for the reflection node 200 to obtain configuration data. In some embodiments, the configuration data is obtained from the network node 300a on the control channel 130 before the link failure event is determined. In other embodiments, the configuration data is pre-configured in the reflection node 200. In either case, but particularly in the latter case, the configuration data can be standardized configuration data, at least based on a standard, or defined by predefined rules. In some examples, the configuration data is obtained as a combination of configuration data from the network node 300a (e.g., as an indicator signaled from the network node 300a) and predefined rules (e.g., where the indicator points to one of the predefined rules, which can be set in the standard).

[0051] There may be different types of link failures. Generally speaking, the type of link failure depends on the operational connection between the reflection node 200 and the network node 300a. In some embodiments, the reflection node 200 has a wireless connection toward the network node 300a for the control channel 130 and the link failure is a radio link failure. For example, if the control channel 130 is on a wireless connection, the radio link quality of the control channel 130 can be monitored, and if the radio link quality is below a threshold quality level for a certain period of time (or the number of decoding errors of packets sent on the control channel 130 is above an error threshold for a certain period of time), a radio link failure event defining a link failure event is detected. In other embodiments, the reflection node 200 has a wired connection toward the network node 300a for the control channel 130 and the link failure is a failure on the wired link.

[0052] As described above, the control channel 130 may be on a different frequency interval than the communication channels 120a: 120d. That is, in some embodiments, the communication channels 120a: 120d are using a first carrier frequency (in a first frequency interval f1) and the control channel 130 is using a second carrier frequency (in a second frequency interval f2) that is different from the first carrier frequency.

[0053] As described above, under normal operation (i.e., when there is no link failure on the control channel 130), the reflection node 200 is instructed by the network node 300a on how to control the reflection angle of the passive meta-surface 250. That is, in some embodiments, the instructions received from the network node 300a are related to the reflection settings, and in the absence of a link failure event on the control channel 130, the reflection angle of the passive meta-surface 250 will be controlled according to the reflection settings.

[0054] Now refer to Figure 9 An embodiment of a network node 300a for handling a link failure towards a reflective node 200 is disclosed, which will also be described further below.

[0055] The network node 300a includes a communication interface 320 for sending instructions to the reflection node 200 over the control channel 130 and for communicating with at least one wireless device 400a, 400b over the communication channels 120a, 120d using radio waves. The radio waves are reflected at a reflection angle at the passive element surface 250 of the reflection node 200 between the network node 300a and the wireless device 400a, 400b.

[0056] The network node 300a comprises a processing circuit 310 configured to determine a link failure event on the control channel 130 between the network node 300a and the reflection node 200 .

[0057] The processing circuit 310 is configured to control the communication interface 320 to communicate with the wireless devices 400a, 400b according to the configuration data during a link failure event. The configuration data specifies a reflection setting according to which the reflection angle at the passive element surface 250 of the reflective node 200 is to be controlled during a link failure event.

[0058] The embodiments disclosed above in conjunction with the description of the reflection node 200 are also applicable to the network node 300a. However, for the sake of completeness of the present disclosure, embodiments applicable to and relating to further details of the network node 300a will now be disclosed.

[0059] As described above, there are different possible examples of configuration data. Three embodiments related thereto are now disclosed in sequence.

[0060] According to a first embodiment, the reflection angle used immediately before a link failure event is determined is retained based on configuration data. In this regard, while a link failure is ongoing, the reflection angle may change by at least one factor. For example, the reflection angle may change at a time defined by a timer. Thus, the reflection angle may be retained until the timer expires, after which one or more different reflection angles may be used. Specifically, based on configuration data, the reflection angle used immediately before a link failure event is determined may be retained only until the timer, which was initiated when the link failure event was determined, expires.

[0061] Different methods can be used to determine the timer value, i.e., the duration from the timer start until the timer expires. In some examples, the timer is aligned with the link reestablishment process. That is, in some aspects, after a link failure event is determined, a reestablishment process is initiated between reflection node 200 and network node 300a. The reestablishment process takes place within a maximum time period, and the timer may then have an expiration time equal to this time period. If the timer expires before the link failure is resolved, different methods can be used to determine the reflection angle. In some examples, the reflection angle uses a value defined by a default setting. Specifically, in some aspects, when a link failure event is still ongoing after the timer expires, the reflection angle is defined by the default reflection setting according to the configuration data.

[0062] According to a second embodiment, the reflection angle is defined by one or more default reflection settings according to the configuration data.

[0063] According to a third embodiment, the reflection angle may be changed according to a set of reflection settings based on configuration data. The set of reflection settings may include the reflection angle used immediately before a link failure event was determined and a default reflection setting. Further in this regard, the reflection angle may be periodically changed between the reflection settings in the set of reflection settings based on the configuration data. For example, the reflection angle may be periodically changed based on time information (e.g., provided by a timestamp). In particular, the configuration data may include a timestamp, wherein the timestamp defines how the reflection angle changes over time between the reflection settings in the set of reflection settings. Furthermore, in some examples, the timestamp defines when broadcast symbols will be sent and when unicast symbols will be sent. That is, in some aspects, broadcast symbols and unicast symbols are transmitted on communication channels 120a:120d between network node 300a and wireless devices 400a, 400b, and the timestamps are defined by when the broadcast symbols will be sent and when the unicast symbols will be sent. In a further example, the timestamps are replaced by triggers provided by one or more timers, such that when the timers expire, this triggers the reflection angle to be changed. That is, when the first timer expires, this triggers the first change in the reflection angle. Then, when the second timer expires, this triggers a second change in the reflection angle, and so on. Thus, the timers can be used to sequentially change the reflection angle from one value to the next. In a further example, a default setting is used for broadcast symbols, while the last used setting is retained for unicast symbols. That is, in some aspects, according to the configuration data, the reflection angle is defined by a first setting when transmitting broadcast symbols, while the reflection angle is defined by a second setting when transmitting unicast symbols. Furthermore, in some examples, the first setting is the default reflection setting, while according to the second setting, the reflection angle used immediately before determining a link failure event is used when transmitting broadcast symbols.

[0064] In some embodiments, the reflection angle of each portion of the passive meta-surface 250 is different according to the configuration data.

[0065] In some aspects, the network node 300a provides the configuration data to the reflection node 200. Specifically, in some embodiments, the configuration data is provided to the reflection node 200 over the control channel 130 prior to determining the link failure event.

[0066] As described above, different types of link failures are possible, and generally speaking, the type of link failure depends on the operational connection between the network node 300a and the reflection node 200. In some embodiments, the network node 300a has a wireless connection to the reflection node 200 for the control channel 130 and the link failure is a radio link failure. In other embodiments, the network node 300a has a wired connection to the reflection node 200 for the control channel 130 and the link failure is a failure on the wired link.

[0067] As described above, the control channel 130 may be on a different frequency interval than the communication channels 120a: 120d. That is, in some embodiments, the communication channels 120a: 120d are using a first carrier frequency (in a first frequency interval f1) and the control channel 130 is using a second carrier frequency (in a second frequency interval f2) that is different from the first carrier frequency.

[0068] As described above, under normal operation (i.e., when there is no link failure on the control channel 130), the network node 300a instructs the reflection node 200 on how to control the reflection angle of the passive meta-surface 250. That is, in some embodiments, the instructions sent to the reflection node 200 are related to the reflection settings, and in the absence of a link failure event on the control channel 130, the reflection angle of the passive meta-surface 250 will be controlled according to the reflection settings.

[0069] Now refer to Figure 5 , which illustrates a method for handling a link failure toward a network node 300a, performed by a reflection node 200 according to any of the above-disclosed embodiments. The reflection node 200 includes a passive metasurface 250 having a controllable reflection angle, which is configured to reflect radio waves on communication channels 120a:120d between the network node 300a and wireless devices 400a, 400b. The reflection node 200 receives instructions from the network node 300a over a control channel 130.

[0070] S102: The reflection node 200 determines a link failure event on the control channel 130 between the reflection node 200 and the network node 300a.

[0071] In response to this (ie, in response to having determined a link failure event), the reflective node 200 performs step S104 .

[0072] S104: The reflection node 200 controls the reflection angle of the passive meta-surface 250 for reflecting radio waves on the communication channels 120a:120d during a link failure event and using the reflection settings specified by the configuration data.

[0073] Now refer to Figure 6 , which illustrates a method performed by a network node 300a for handling a link failure toward a reflection node 200 according to any of the above-disclosed embodiments. The network node 300a sends instructions to the reflection node 200 over a control channel 130. The network node 300a communicates with at least one wireless device 400a, 400b over communication channels 120a and 120d using radio waves. The radio waves are reflected at a reflection angle at the passive element surface 250 of the reflection node 200 between the network node 300a and the wireless device 400a, 400b.

[0074] S202 : The network node 300 a determines a link failure event on the control channel 130 between the network node 300 a and the reflection node 200 .

[0075] In response to this (ie, in response to having determined a link failure event), the network node 300a performs step S204.

[0076] S204: The network node 300a communicates with the wireless devices 400a, 400b according to the configuration data during the link failure event. The configuration data specifies the reflection settings according to which the reflection angle at the passive element surface 250 of the reflection node 200 is to be controlled during the link failure event.

[0077] A specific embodiment for handling a link failure between the reflection node 200 and the network node 300a based at least on some of the embodiments disclosed above will now be disclosed.

[0078] The transceiver unit 270 in the reflection node 200 obtains configuration data that the reflection node 200 should use if the transceiver unit 270 determines a link failure event on the control channel 130. The configuration data specifies reflection settings to be used by the controller 260 in the reflection node 200 for controlling the reflection angle of the passive meta-surface 250 for reflecting radio waves on a communication channel between the network node 300a and the wireless devices 400a, 400b via the reflection node 200.

[0079] The transceiver unit 270 or the controller 260 via the transceiver unit 270 monitors the quality of the control channel 130. This enables the reflex node 200 to determine a link failure event of the control channel 130 according to well-known configuration procedures.

[0080] The controller 260 controls the reflection angle of the passive meta-surface 250 during a link failure event according to the configuration data. Examples of configuration data and one or more values ​​that the reflection angle may take according to the configuration data have been disclosed above.

[0081] The reflection node 200 initiates a connection reestablishment process to reconnect to the control channel 130 of the network node 300a. The reestablishment process may follow any well-known reestablishment process. The reestablishment process may last for a period of time (e.g., until a timer expires), and if the connection is not established before the timer expires, it is determined that the connection will be released.

[0082] Figure 7 The components of the reflective node 200 according to one embodiment are schematically shown in the form of a plurality of functional units. Figure 11The processing circuit 210 may be provided by any combination of one or more of a suitable central processing unit (CPU), a multiprocessor, a microcontroller, a digital signal processor (DSP), etc., which executes software instructions in a manner similar to that in the example embodiment of the present invention. The processing circuit 210 may further be provided as at least one application specific integrated circuit (ASIC) or a field programmable gate array (FPGA).

[0083] In particular, the processing circuit 210 is configured to cause the reflective node 200 to perform a set of operations or steps, as disclosed above. For example, the storage medium 230 may store the set of operations, and the processing circuit 210 may be configured to retrieve the set of operations from the storage medium 230 to cause the reflective node 200 to perform the set of operations. The set of operations may be provided as a set of executable instructions. Thus, the processing circuit 210 is thereby arranged to perform the method as disclosed herein.

[0084] The storage medium 230 may also include a persistent storage device, which may be, for example, any one or combination of magnetic memory, optical memory, solid-state memory, or even remotely mounted memory.

[0085] The reflection node 200 may further comprise a communication interface 220 for communicating with at least one network node 300a, 300b. Thus, the communication interface 220 may comprise one or more transmitters and receivers, including analog and digital components.

[0086] The processing circuit 210 controls the general operation of the reflection node 200, for example, by sending data and control signals to the communication interface 220 and the storage medium 230, by receiving data and reports from the communication interface 220, and by retrieving data and instructions from the storage medium 230. Other components of the reflection node 200 and related functions are omitted in order not to obscure the concepts presented herein.

[0087] Figure 8 Components of the reflective node 200 according to one embodiment are schematically illustrated in the form of a plurality of functional modules. Figure 8 The reflective node 200 includes a plurality of functional modules; a determination module 210a configured to execute step S102; and a control module 210b configured to execute step S104. Figure 8The reflection node 200 may also include a plurality of optional functional modules, such as represented by functional module 210c. In general, each functional module 210a-210c may be implemented in hardware or software. Preferably, one or more or all functional modules 210a-210c may be implemented by processing circuitry 210, possibly in conjunction with communication interface 220 and / or storage medium 230. Processing circuitry 210 may therefore be arranged to retrieve instructions provided by functional modules 210a-210c from storage medium 230 and execute these instructions, thereby performing any of the steps of the reflection node 200 as disclosed herein.

[0088] Figure 9 Components of the network nodes 300a, 300b according to one embodiment are schematically shown in the form of a plurality of functional units. Figure 11 The processing circuit 310 may be provided by any combination of one or more of a suitable central processing unit (CPU), a multiprocessor, a microcontroller, a digital signal processor (DSP), etc., which may be implemented as software instructions in a processor (such as a processor or a processor). The processing circuit 310 may further be provided as at least one application specific integrated circuit (ASIC) or a field programmable gate array (FPGA).

[0089] In particular, processing circuit 310 is configured to cause network nodes 300a, 300b to perform a set of operations or steps, as disclosed above. For example, storage medium 330 may store the set of operations, and processing circuit 310 may be configured to retrieve the set of operations from storage medium 330 to cause network nodes 300a, 300b to perform the set of operations. The set of operations may be provided as a set of executable instructions. Thus, processing circuit 310 is thereby arranged to perform the method as disclosed herein.

[0090] The storage medium 330 may also include a persistent storage device, which may be, for example, any one or combination of magnetic memory, optical memory, solid-state memory, or even remotely mounted memory.

[0091] The network nodes 300a, 300b may also include a communication interface 320 for communicating with the reflection node 200 and the wireless devices 400a, 400b. Thus, the communication interface 320 may include one or more transmitters and receivers, including analog and digital components.

[0092] The processing circuit 310 controls the general operation of the network nodes 300a, 300b, for example, by sending data and control signals to the communication interface 320 and the storage medium 330, by receiving data and reports from the communication interface 320, and by retrieving data and instructions from the storage medium 330. Other components of the network nodes 300a, 300b and related functionality are omitted so as not to obscure the concepts presented herein.

[0093] Figure 10 Components of the network nodes 300a, 300b according to one embodiment are schematically shown in the form of a plurality of functional modules. Figure 10 The network nodes 300a and 300b include multiple functional modules; a determination module 310a configured to execute step S202; and a control module 310b configured to execute step S204. Figure 10 The network nodes 300a, 300b may also include a plurality of optional functional modules, such as represented by functional module 310c. In general, each functional module 310a-310c may be implemented in hardware or software. Preferably, one or more or all functional modules 310a-310c may be implemented by processing circuitry 310, possibly in cooperation with communication interface 320 and / or storage medium 330. Processing circuitry 310 may therefore be arranged to retrieve instructions, such as provided by functional modules 310a-310c, from storage medium 330 and execute these instructions, thereby performing any of the steps of the network nodes 300a, 300b as disclosed herein.

[0094] The network nodes 300a, 300b may be part of, integrated with, or co-located with any of a (radio) access network node, a radio base station, a base transceiver station, a Node B (NB), an evolved Node B (eNB), a gNB, an access point, an access node, or an integrated access and backhaul (IAB) node.

[0095] The network nodes 300a and 300b may be provided as standalone devices or as part of at least one additional device. For example, the network nodes 300a and 300b may be provided in a node of a radio access network or a node of a core network. Alternatively, the functionality of the network nodes 300a and 300b may be distributed between at least two devices or nodes. These at least two nodes or devices may be part of the same network portion (e.g., a radio access network or a core network) or may be distributed between at least two such network portions.

[0096] Thus, a first portion of the instructions executed by network nodes 300a, 300b may be executed in a first device, and a second portion of the instructions executed by network nodes 300a, 300b may be executed in a second device; the embodiments disclosed herein are not limited to any particular number of devices on which the instructions executed by network nodes 300a, 300b may be executed. Thus, methods according to embodiments disclosed herein are suitable for execution by network nodes 300a, 300b residing in a cloud computing environment. Thus, while Figure 9 A single processing circuit 310 is shown in FIG, but the processing circuit 310 may be distributed among multiple devices or nodes. The same applies to Figure 8 10 functional modules 310a-310c and Figure 11 Computer program 1120b.

[0097] Figure 11 An example of a computer program product 1110a, 1110b including a computer-readable device 1130 is shown. The computer-readable device 1130 may store a computer program 1120a that causes the processing circuit 210 and entities and devices operatively coupled thereto (e.g., the communication interface 220 and the storage medium 230) to perform methods according to the embodiments described herein. The computer program 1120a and / or the computer program product 1110a may thus provide means for performing any of the steps of the reflection node 200 as disclosed herein. The computer-readable device 1130 may store a computer program 1120b that causes the processing circuit 310 and entities and devices operatively coupled thereto (e.g., the communication interface 320 and the storage medium 330) to perform methods according to the embodiments described herein. The computer program 1120b and / or the computer program product 1110b may thus provide means for performing any of the steps of the network nodes 300a, 300b as disclosed herein.

[0098] exist Figure 11In the example of FIG, the computer program products 1110a, 1110b are shown as optical discs, such as CDs (Compact Discs), DVDs (Digital Versatile Discs), or Blu-ray Discs. The computer program products 1110a, 1110b may also be embodied as memories, such as random access memories (RAMs), read-only memories (ROMs), erasable programmable read-only memories (EPROMs), or electrically erasable programmable read-only memories (EEPROMs), more specifically as non-volatile storage media in devices such as external memories, such as USB (Universal Serial Bus) memories or flash memories (e.g., Compact Flash). Thus, although the computer programs 1120a, 1120b are schematically shown herein as tracks on the optical discs shown, the computer programs 1120a, 1120b may be stored in any manner suitable for the computer program products 1110a, 1110b.

[0099] The inventive concept has mainly been described above with reference to a few embodiments. However, as readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the inventive concept as defined by the appended patent claims.

Claims

1. A reflection node (200) for handling a link failure towards a network node (300a, 300b), the reflection node (200) comprising: A controller (260) for controlling a passive meta-surface (250) having a controllable reflection angle, the passive meta-surface being configured to reflect radio waves on a communication channel (120a, 120d) between a network node (300a, 300b) and a wireless device (400a, 400b); as well as a transceiver unit (270) for receiving instructions from the network node (300a, 300b) on a control channel (130); wherein the transceiver unit (270) is configured to determine a link failure event on the control channel (130) between the reflection node (200) and the network node (300a, 300b); and The controller (260) is configured to control the reflection angle of the passive meta-surface (250) for reflecting the radio waves on the communication channel (120a:120d) using a reflection setting specified by configuration data during the link failure event.

2. The reflection node (200) according to claim 1, wherein The reflection angle used immediately before determining the link failure event is maintained according to the configuration data.

3. The reflection node (200) according to claim 2, wherein: According to the configuration data, the reflection angle used immediately before the link failure event is determined is maintained only until expiration of a timer started when the link failure event is determined.

4. The reflection node (200) according to claim 3, wherein: After the link failure event has been determined, a reestablishment process is initiated between the reflex node (200) and the network node (300a, 300b), wherein the reestablishment process is performed during at most a time period, and wherein the timer has an expiry time equal to the time period.

5. The reflection node (200) according to claim 4, wherein: When the link failure event is still ongoing after the timer expires, the reflection angle is defined by a default reflection setting according to the configuration data.

6. The reflection node (200) according to any one of claims 1 to 5, wherein: The reflection angle is defined by a default reflection setting according to the configuration data.

7. The reflection node (200) according to any one of claims 1 to 5, wherein: According to the configuration data, the reflection angle is changed according to a set of reflection settings.

8. The reflection node (200) according to claim 7, wherein: The reflection angle is periodically varied between reflection settings in the set of reflection settings according to the configuration data.

9. The reflection node (200) according to claim 7, wherein: The configuration data comprises a timestamp, and wherein the timestamp defines how the reflection angle is to be changed over time between reflection settings in the set of reflection settings.

10. The reflection node (200) according to claim 9, wherein: Broadcast symbols and unicast symbols are transmitted over the communication channel (120a:120d) between the network node (300a, 300b) and the wireless device (400a, 400b), and wherein the timestamp is defined by a time at which a broadcast symbol is to be sent and a time at which a unicast symbol is to be sent.

11. The reflection node (200) according to claim 10, wherein: According to the configuration data, when the broadcast symbol is transmitted, the reflection angle is defined by a first setting, and when the unicast symbol is transmitted, the reflection angle is defined by a second setting.

12. The reflection node (200) according to claim 11, wherein: The first setting is a default reflection setting, and wherein, according to the first setting, the reflection angle used immediately before determining the fault event is to be used when transmitting the broadcast symbols.

13. The reflection node (200) according to any one of claims 1 to 5, wherein: The passive meta-surface (250) comprises at least two passive meta-surface portions, and wherein, according to the configuration data, the reflection angle is different for each of the at least two passive meta-surface portions.

14. The reflection node (200) according to any one of claims 1 to 5, wherein: The configuration data is obtained from the network node (300a, 300b) via the control channel (130) before the link failure event has been determined.

15. The reflection node (200) according to any one of the preceding claims 1 to 5, wherein The configuration data is pre-configured in the reflection node (200).

16. The reflection node (200) according to any one of claims 1 to 5, wherein: The reflex node (200) has a wireless connection towards the network node (300a, 300b) for the control channel (130), and wherein the link failure is a radio link failure.

17. The reflection node (200) according to any one of claims 1 to 5, wherein: The communication channel uses a first carrier frequency, and wherein the control channel (130) uses a second carrier frequency different from the first carrier frequency.

18. The reflection node (200) according to any one of claims 1 to 5, wherein: The instructions received from the network node (300a, 300b) relate to a reflection setting according to which the reflection angle of the passive metasurface (250) is controlled in the absence of the link failure event on the control channel (130).

19. The reflective node (200) according to any one of claims 1 to 5, further comprising the passive meta-surface (250).

20. A method for handling a link failure towards a network node (300a, 300b), the method being performed by a reflex node (200), wherein: The reflection node (200) comprises a passive metasurface (250) having a controllable reflection angle, the passive metasurface being used to reflect radio waves on a communication channel (120a:120d) between the network node (300a, 300b) and a wireless device (400a, 400b), wherein the reflection node (200) receives instructions from the network node (300a, 300b) on a control channel (130), and the method comprises: determining (S102) a link failure event on the control channel (130) between the reflection node (200) and the network node (300a, 300b); and in response thereto: During the link failure event, the reflection angle of the passive meta-surface (250) is controlled (S104) using a reflection setting specified by configuration data for reflecting the radio waves on the communication channel (120a:120d).

21. A network node (300a, 300b) for handling a link failure towards a reflector node (200), the network node (300a, 300b) comprising: a communication interface (320) for sending instructions to the reflection node (200) on a control channel (130) and for communicating with at least one wireless device (400a, 400b) on a communication channel (120a:120d) using radio waves, wherein the radio waves are reflected at a reflection angle at a passive element surface (250) of the reflection node (200) between the network node (300a, 300b) and the wireless device (400a, 400b); and a processing circuit (310) configured to determine a link failure event on the control channel (130) between the network node (300a, 300b) and the reflection node (200); The processing circuit (310) is configured to control the communication interface (320) for communicating with the wireless device (400a, 400b) according to configuration data during the link failure event, wherein the configuration data specifies a reflection setting, according to which the reflection angle at the passive element surface (250) of the reflective node (200) is controlled during the link failure event.

22. The network node (300a, 300b) of claim 21, wherein: The reflection angle used immediately before determining the link failure event is maintained according to the configuration data.

23. The network node (300a, 300b) of claim 22, wherein: According to the configuration data, the reflection angle used immediately before the link failure event is determined is maintained only until expiration of a timer started when the link failure event is determined.

24. The network node (300a, 300b) of claim 23, wherein: After the link failure event has been determined, a reestablishment procedure is initiated between the reflex node (200) and the network node (300a, 300b), wherein the reestablishment procedure is performed during at most a time period, and wherein the timer has an expiry time equal to the time period.

25. The network node (300a, 300b) of claim 24, wherein When the link failure event is still ongoing after the timer expires, the reflection angle is defined by a default reflection setting according to the configuration data.

26. The network node (300a, 300b) according to any one of claims 21 to 25, wherein The reflection angle is defined by a default reflection setting according to the configuration data.

27. The network node (300a, 300b) according to any one of claims 21 to 25, wherein According to the configuration data, the reflection angle is changed according to a set of reflection settings.

28. The network node (300a, 300b) of claim 27, wherein The reflection angle is periodically varied between reflection settings in the set of reflection settings according to the configuration data.

29. The network node (300a, 300b) of claim 27, wherein: The configuration data comprises a timestamp, and wherein the timestamp defines how the reflection angle changes over time between reflection settings in the set of reflection settings.

30. The network node (300a, 300b) of claim 29, wherein Broadcast symbols and unicast symbols are transmitted over the communication channel (120a:120d) between the network node (300a, 300b) and the wireless device (400a, 400b), and wherein the timestamp is defined by a time at which a broadcast symbol is to be sent and a time at which a unicast symbol is to be sent.

31. The network node (300a, 300b) of claim 30, wherein: According to the configuration data, when the broadcast symbol is transmitted, the reflection angle is defined by a first setting, and when the unicast symbol is transmitted, the reflection angle is defined by a second setting.

32. The network node (300a, 300b) of claim 31, wherein: The first setting is a default reflection setting, and wherein, according to the second setting, the reflection angle used immediately before determining the link failure event is to be used when transmitting the broadcast symbols.

33. The network node (300a, 300b) of claim 31, wherein: The passive meta-surface (250) comprises at least two passive meta-surface portions, and wherein, according to the configuration data, the reflection angle is different for each of the at least two passive meta-surface portions.

34. The network node (300a, 300b) according to any one of claims 21 to 25, wherein The configuration data is provided to the reflection node (200) via the control channel (130) before the link failure event has been determined.

35. The network node (300a, 300b) according to any one of claims 21 to 25, wherein The network node (300a, 300b) has a wireless connection towards the reflex node (200) for the control channel (130), and wherein the link failure is a radio link failure.

36. The network node (300a, 300b) according to any one of claims 21 to 25, wherein The communication channel uses a first carrier frequency, and wherein the control channel (130) uses a second carrier frequency different from the first carrier frequency; and / or The instructions sent to the reflection node (200) are related to reflection settings, according to which the reflection angle of the passive metasurface (250) is controlled in the absence of the link failure event on the control channel (130).

37. A method for handling a link failure towards a reflective node (200), the method being performed by a network node (300a, 300b), wherein: The network node (300a, 300b) sends an instruction to the reflection node (200) on a control channel (130), and wherein the network node (300a, 300b) communicates with at least one wireless device (400a, 400b) on a communication channel (120a:120d) using radio waves, wherein the radio waves are reflected at a reflection angle at a passive element surface (250) of the reflection node (200) between the network node (300a, 300b) and the wireless device (400a, 400b), the method comprising: determining (S202) a link failure event on the control channel (130) between the network node (300a, 300b) and the reflection node (200); and in response thereto: During the link failure event, communicating (S204) with the wireless device (400a, 400b) according to configuration data, wherein the configuration data specifies a reflection setting, according to which the reflection angle at the passive element surface (250) of the reflection node (200) is controlled during the link failure event.

38. A computer program product (1110a, 1110b), comprising: A computer program (1120a) for handling a link failure towards a network node (300a, 300b), and a computer-readable storage medium (1130) on which said computer program is stored; The computer program comprises computer code which, when executed on a processing circuit (210) of a reflection node (200), causes the reflection node (200) to perform the following operations, wherein the reflection node (200) comprises a passive metasurface (250) having a controllable reflection angle, the passive metasurface being configured to reflect radio waves on a communication channel (120a, 120d) between the network node (300a, 300b) and a wireless device (400a, 400b), and wherein the reflection node (200) receives an instruction from the network node (300a, 300b) on a control channel (130): determining (S102) a link failure event on the control channel (130) between the reflection node (200) and the network node (300a, 300b); and in response thereto: During the link failure event, the reflection angle of the passive element surface (250) is controlled (S104) using a reflection setting specified by configuration data for reflecting the radio waves on the communication channel (120a:120d).

39. A computer program product (1110a, 1110b), comprising: A computer program (1120b) for handling a link failure towards a reflective node (200), and a computer readable storage medium (1130) on which said computer program is stored; The computer program comprises computer code which, when executed on a processing circuit (310) of a network node (300a, 300b), causes the network node (300a, 300b) to perform the following operations, wherein the network node (300a, 300b) sends instructions to the reflection node (200) on a control channel (130), and wherein the network node (300a, 300b) communicates with at least one wireless device (400a, 400b) on a communication channel (120a:120d) using radio waves, wherein the radio waves are reflected at a reflection angle at a passive element surface (250) of the reflection node (200) between the network node (300a, 300b) and the wireless device (400a, 400b): determining (S202) a link failure event on the control channel (130) between the network node (300a, 300b) and the reflection node (200); and in response thereto: During the link failure event, communicating (S204) with the wireless device (400a, 400b) according to configuration data, wherein the configuration data specifies a reflection setting, according to which the reflection angle at the passive element surface (250) of the reflective node is controlled during the link failure event.

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