Backhaul link control for intelligent repeaters

Abstract

The invention proposes a wireless network comprising a master station communicating with one or more end stations via a secondary station configured to relay signals between the master station and the one or more end stations, the secondary station exchanging data with the master station over a backhaul link and with the end stations over an access link, the network comprises an access link manager for managing an access link between the secondary station and the terminal station from a measured quality derived from channel state information exchanged between the primary station and the terminal station, and a backhaul link estimator for indirectly estimating a quality of a backhaul link between the primary station and the secondary station, and a backhaul link manager to adjust the backhaul link based on the indirect backhaul link estimate.

Description

Technical Field

[0001] The present invention relates to the field of communication services for terminal devices including mobile access devices in wireless networks, such as but not limited to smart repeaters or reflective smart surfaces used in terrestrial networks or satellites used in non-terrestrial networks. Background Art

[0002] RF repeaters have been a feature of cellular networks for some years, where their ability to economically patch holes in cell coverage has put them in a useful role. Prior to release 18, cellular repeaters compromised two back-to-back amplifying repeater chains, each of which itself consisted of an input stage, some elements to filter out out-of-band signals, and an amplifier. When the input and output are connected to appropriate antenna systems, one covering the so-called access channel between the repeater and the terminal, and the other covering the so-called backhaul between the access device and the repeater, the repeater provides transparent on-channel repeater service to terminal devices (e.g., user equipment (UE)) that may not be outside the direct coverage of an access device (e.g., a base station or access point).

[0003] A particular advantage of this approach is that the protocol between the access equipment and the terminal equipment does not need to be changed, which means that the repeater is fully compatible with the cellular system.

[0004] In recent standards work, attention is being paid to improving the performance of repeaters by allowing aspects of their behavior to be controlled by access equipment. One problem with repeaters prior to Release 18 was that they were always "on", i.e. the amplifier was always operational. This was true even if there was no signal to repeat. In this case, the amplifier simply relayed any noise and interference at its input to the output. This meant that the area served by the repeater could suffer from higher levels of background noise and interference. Instead, noise picked up at the input on the uplink side of the repeater was sent towards the access equipment.

[0005] Therefore, now consider allowing the access device to control when the repeater's amplifier is turned on and what level of amplifier gain should be used. Since in cellular and some wireless networks the access device has overall responsibility for scheduling the use of the frequency range over which it operates, the access device has the necessary knowledge, both uplink and downlink, to determine when the repeater amplifier should be turned on. Improved operation can be achieved by arranging for a local controller in the repeater, connected to the access device via a control channel, to operate the repeater according to the needs of the access device.

[0006] Such a repeater is referred to as a network controlled repeater (NCR) to distinguish it from a conventional uncontrolled repeater. In this specification, the term "intelligent repeater" is assumed to be the same as an NCR.

[0007] Advantageously, the local controller, referred to as the NCR-MT, operates according to at least a subset of the cellular protocol used between the access device and the terminal device and can be treated as a standard terminal device at least on the control side. In this regard, one difference between the backhaul and control channels is that the control channel terminates at the NCR-MT and signals sent to the NCR-MT are not forwarded to the access channel.

[0008] For 5G, it is envisaged that repeaters will have specific values ​​in the 5G FR2 frequency range, which covers the so-called mmWave frequencies (24250MHz-52600 MHz) (TS 38.101-1). The shorter range of mmWave frequencies compared to their FR1 counterparts (410-7125MHz) means that achieving uniform coverage of a given area will be more challenging for frequency bands in the FR2 range, and repeaters can be a valuable tool in network planning. The same may be true in other networks, where there is a trend to use higher frequencies to obtain improved bandwidth and latency. MIMO techniques like beamforming are already used at lower frequencies to improve coverage and reliability. The use of mmWave frequencies provides a greatly increased range for MIMO and future systems to take full advantage of. Therefore, in order to optimize the RF path between the access device and the repeater and between the repeater and the terminal device, we can expect smart repeaters to have beamforming capabilities on the so-called access side (between the repeater and the terminal device) and the so-called backhaul side (between the access device and the repeater). Both sets of beams need to be controlled by the access device.

[0009] Typically, information used to configure beamforming operations and other signaling aspects is obtained by exchanging channel sounding signals (sometimes collectively referred to as channel state information (CSI) signals) between the access device and the terminal device with the transmitter using feedback reported by the receiver to provide closed-loop control of the beam. For NCR, a similar process is used to manage the control link between the access device and the NCR-MT.

[0010] For the terminal device, the relay introduces an additional link - the backhaul that is not explicitly considered by the CSI mechanism. Because there is no entity within the relay that can perform the necessary lower layer UE functionality for CSI reporting across the backhaul and there is no mechanism for uplink beam steering, this means that the CSI information exchanged between the access device and the terminal device actually reports a concatenated combination of the backhaul link and the access link. In the case of a report of poor channel quality, which link needs to be adjusted?

[0011] An alternative to using amplifiers for the repeater function is to use switchable metasurfaces. Switchable metasurfaces have been developed recently and offer many possibilities for improving the wireless communication path between access devices and terminal devices of a wireless network.

[0012] Various techniques can be employed to realize such switchable metasurfaces. Typically, electronically switched metasurfaces are employed, but physically movable reflective patches are also a viable technology. In general, there is no reason why these surfaces cannot be constructed by using any relevant technology, as long as the general set of desired properties is achieved. Metasurfaces can even be used to form independent communication infrastructure using backscattered ambient radio signals.

[0013] The metasurface may be composed of periodic subwavelength metal / dielectric antennas that resonantly couple to the electric or magnetic or both components of the incident electromagnetic field, exhibiting an effective electric (represented by the dielectric constant ε) and / or magnetic (represented by the magnetic permeability μ) response that is not found in nature.

[0014] Metasurfaces therefore represent a general concept for manipulating electromagnetic waves. The microwave frequency range presents significant application potential due to the ease of fabrication using planar circuits. Huygens metasurfaces have received significant attention as their characteristics approach unit transmission and effectively suppress reflection artifacts. For microwave frequencies, Huygens metasurfaces are typically fabricated in a printed circuit board (PCB) process, where three structured copper layers are separated by a low-loss dielectric substrate.

[0015] Metamaterials will be useful in many aspects of, for example, 5G wireless communication solutions. Syed S. Bukhari et al.: "A Metasurfaces Review: Definitions and Applications" reviews metasurfaces. Purely passive metasurfaces are useful, but only act as a permanent change in the transmission environment.

[0016] Kun Woo Cho et al. proposed a reconfigurable metasurface for millimeter wave networks ("mmWall"). :"mmWall: A Reconfigurable Metamaterial Surface for mmWave Networks", which is a tunable smart surface made of metamaterials, which, unlike conventional wireless relay systems, does not have transmit and receive antennas, nor amplifiers. Once the incoming beam hits the metasurface, it naturally refracts the beam to the desired direction, regardless of whether the transmitter and receiver are in the same room ("mirror" mode) or in different rooms ("lens" mode). In addition, it can split the incoming signal into multiple beams and steer multi-arm beams simultaneously. The authors used "Huygen's metasurface" to implement their design.

[0017] However, there are other technologies for switchable millimeter-wave manipulation surfaces that are separate from metasurfaces.

[0018] In addition, a large intelligent surface (LIS) and a model for integrating base stations and LIS to determine the benefits of different proportions of each in a communication network are disclosed in "Stochastic Geometry Analysis of LargeIntelligent Surface-Assisted Millimeter Wave Networks" by Yongxu Zhu et al. They concluded that the contribution of LIS is good in the case of a limited number of base stations, but this is not the case with many base stations serving users.

[0019] Furthermore, in “A Survey of Intelligent Reflecting Surfaces (IRSs): Towards 6G Wireless Communication Networks” by Jun Zhao et al., the authors refer to such surfaces as “intelligent reflective surfaces” and the behavior is limited to reflection rather than both reflection and transmission.

[0020] For the metasurface, there are still two parts to the link between the access device and the terminal device, and there is still only one set of channel quality information that effectively covers both links in series. So again, in the case of poor channel quality, it is necessary to determine which part of the link needs to be adjusted. Summary of the invention

[0021] An object of the present invention is to improve the handling of poor link quality experienced by access devices and terminal devices when the link passes through a reconfigurable relay device (RRD), such as a smart repeater or an externally controlled RIS that lacks the inherent ability to perform its own radio sensing ("fully passive RIS"), as well as a partially active RIS that may include, for example, some radio capability, signal processing capability, sensors, motors for changing the orientation of individual sub-panels / sub-elements of the RIS, or active elements that not only modify the angle / polarization of the reflected electromagnetic waves, but also amplify them, etc.

[0022] The object is achieved by a secondary station, a method and a network as defined in the set of appended claims and which can be implemented by a computer program product.

[0023] According to the first definition of the present invention, in a first aspect, a method for operating a network is proposed, the network comprising a main station communicating with a terminal station via a secondary station, the secondary station being configured to relay signals exchanged between the main station and the terminal station, the secondary station exchanging data with the main station on a backhaul link and exchanging data with the terminal station on a dedicated access link.

[0024] The method comprises managing the access link based on the measured quality or indirect estimation of the channel quality between the master station and the terminal station, and

[0025] The quality of the backhaul link is managed based on indirect estimation or according to measured quality.

[0026] Similarly, in a second aspect of the present invention, a method for operating a master station in a network is proposed, wherein the master station communicates with one or more terminal stations via an auxiliary station, wherein the auxiliary station is configured to relay signals exchanged between the master station and the one or more terminal stations, and the auxiliary station exchanges data with the master station on a backhaul link and exchanges data with the terminal station on a dedicated access link.

[0027] The method includes a master station managing access based on the quality of measurements between the master station and the terminal station, and

[0028] The primary station manages the quality of the backhaul link between the primary station and the secondary station based on indirect estimation or according to measured quality.

[0029] According to a third aspect of the present invention, a method for operating a secondary station in a network is proposed, the network comprising a primary station communicating with one or more terminal stations via the secondary station, the secondary station being configured to relay signals exchanged between the primary station and the terminal station, the secondary station exchanging data with the primary station on a backhaul link and exchanging data with the terminal station on a dedicated access link.

[0030] The method includes the secondary station monitoring a probe signal from the primary station directed to the end station and / or from the end station to the primary station,

[0031] Generate a backhaul link quality report to be sent to the master station.

[0032] Furthermore, according to a fourth aspect of the present definition of the invention, there is proposed a secondary station operating in a network, the network comprising a primary station communicating with a terminal station via the secondary station, the secondary station being configured to relay signals exchanged between the primary station and one or more terminal stations, the secondary station exchanging data with the primary station on a backhaul link and exchanging data with the terminal station on a dedicated access link.

[0033] The secondary station comprises a controller for monitoring a channel state information signal from the primary station for the terminal station, the controller being arranged to control a transmitter to send a backhaul link quality report to be sent to the primary station.

[0034] In addition, according to a fifth aspect of the present definition of the present invention, a method for operating a secondary station in a network is proposed, the network comprising a primary station communicating with a terminal station via the secondary station, the secondary station being configured to relay signals exchanged between the primary station and the terminal station, the secondary station exchanging data with the primary station on a backhaul link and exchanging data with the terminal station on a dedicated access link.

[0035] The method includes sending a probe signal to a primary station, so that an estimation of the backhaul link quality is completed at the primary station.

[0036] According to a sixth aspect of the definition of the present invention, there is proposed an auxiliary station operating in a network, the network comprising a main station communicating with a terminal station via the auxiliary station, the auxiliary station being configured to relay signals exchanged between the main station and the terminal station, the auxiliary station exchanging data with the main station on a backhaul link and exchanging data with the terminal station on an access link.

[0037] The secondary station comprises a transmitter for sending a probing signal to the primary station so that an estimation of the backhaul link quality is done at the primary station.

[0038] According to a seventh aspect of the present definition of the invention, there is provided a master station operating in a network, the master station communicating with a terminal station via a secondary station, the secondary station being configured to relay signals exchanged between the master station and the terminal station, the secondary station exchanging data with the master station on a backhaul link and exchanging data with the terminal station on an access link,

[0039] The primary station is configured to receive a sounding signal from the secondary station and estimate a backhaul link quality based on a measurement of the sounding signal,

[0040] The primary station is configured to adjust the backhaul link based on the backhaul link quality.

[0041] According to an eighth aspect of the present definition of the invention, there is provided a wireless network comprising a primary station communicating with terminal stations via secondary stations, the secondary stations being configured to relay signals between the primary station and one or more terminal stations, the secondary stations exchanging data with the primary station on a backhaul link and exchanging data with the terminal stations on an access link,

[0042] The network includes:

[0043] an access link manager for managing an access link between the secondary station and the terminal station based on a measured quality or an indirect estimate of channel quality between the primary station and the terminal station;

[0044] a backhaul link estimator for indirectly estimating the quality of the backhaul link between the primary station and the secondary station, and

[0045] A backhaul link manager is configured to adjust the backhaul link based on the indirect backhaul link estimate or according to the measured quality.

[0046] According to a first aspect related to an access device (e.g., a base station (gNB) or an access point), there is provided an apparatus for controlling a communication path in a wireless network, the apparatus comprising:

[0047] a registration controller for discovering and / or registering a reconfigurable relay device in a wireless network;

[0048] a path establisher for determining and establishing a wireless communication path to at least one target terminal device via at least one registered reconfigurable relay device; and

[0049] A state controller for controlling a redirection mode of the at least one reconfigurable relay device according to the established wireless communication path; determining independent link quality estimates of a backhaul link between the access device and the at least one reconfigurable relay device and an access link between the at least one reconfigurable relay device and the at least one terminal device; and using the link quality estimates to independently optimize the quality of the access link and the backhaul link.

[0050] According to a second aspect related to an access device (e.g., a base station (gNB) or an access point), there is provided a method for controlling a communication path in a wireless network, the method comprising:

[0051] discovering and / or registering a reconfigurable relay device in a wireless network;

[0052] determining and establishing a wireless communication path with at least one target terminal device via at least one registered reconfigurable relay device; and

[0053] A redirection mode of the at least one reconfigurable relay device is controlled according to the established wireless communication path.

[0054] Independent link quality estimates are determined for a backhaul link between an access device and a reconfigurable relay device and an access link between the reconfigurable relay device and at least one terminal device, and the link quality estimates are used to independently optimize the quality of the access link and the backhaul link.

[0055] According to a third aspect, a reconfigurable relay device (e.g., a RIS or intelligent repeater) is provided, which is configured to control a redirection mode for relaying at least one received wireless signal in response to a relay state command received from a remote controller device of a wireless network to establish a wireless communication path to a target terminal device, wherein the reconfigurable relay device can be set to one of a plurality of configuration states in response to the relay state command, wherein each of the configuration states results in one of a plurality of redirection modes of the received wireless signal, and wherein the plurality of redirection modes include at least one of the following: reflection with a given reflection angle, focusing or defocusing, generation of a plurality of beams, refraction with a given refraction angle, and absorption, and wherein each of the plurality of redirection modes includes a backhaul link between the access device and the reconfigurable relay device, and an access link between the reconfigurable relay device and the at least one terminal device.

[0056] According to a fourth aspect, an access device is provided, which includes the apparatus of the first aspect.

[0057] According to a fifth aspect, there is provided a system comprising at least one access device of the fourth aspect, at least one reconfigurable relay device of the third aspect, and a relay installation database for storing information about installed reconfigurable relay devices.

[0058] Finally, according to a sixth aspect, there is provided a computer program product comprising code means for producing the steps of the method of the second aspect when run on a computer device.

[0059] The proposed path establishment via at least one reconfigurable relay device provides significant benefits for radio communication systems, especially those using high frequencies such as 5G millimeter waves. This is because these frequencies are easily absorbed by many materials and therefore blind spots are more common in these systems.

[0060] A scenario for installing a reconfigurable relay device (RRD) is that the owner of a building wants to improve the reception quality of wireless communications (e.g., based on 5G) within the building. The occupants of the building may be his / her own staff, an Industrial Internet of Things (IIoT) network, or possibly the public (e.g., in a public building). More likely, the owner may want to improve reception on all wireless communication networks that supply individuals in the building. Therefore, it may be desirable for all networks to use RRDs to improve communications with people inside the building. Therefore, the owner of the devices wants to enable them to integrate with the network operator that operates the wireless communications (e.g., based on 5G).

[0061] Another scenario for a reconfigurable relay device is an operator of a vehicle who wants to provide improved reception for passengers. The vehicle in this scenario can be a private car or a multi-passenger vehicle such as a bus, coach or train. In each case, the goal is to provide passengers with network access that is not hindered by the structure of the vehicle.

[0062] The prioritization of the networks may be determined, for example, by statistics of the networks supplying users in the building. In addition, several networks may be provided with paid access to the RRD, possibly prioritizing the use of the RRD based on an auction or fixed fee charged to the first location, second location, etc. in the controller priority list.

[0063] Systems with reconfigurable relay devices such as RIS or smart repeaters may be cheaper than additional base stations. The proposed reconfigurable relay devices may be "passive" in the sense that they are controlled by an external controller, most likely a core network device or access device (e.g., a base station) that performs the search for a communication path. It is possible that some form of radio sensing and internal control could be integrated into these systems, whereby the reconfigurable relay device is responsible for setting its state based on, for example, a beam search to a target terminal device.

[0064] Specifically, the following advantages can be achieved:

[0065] ●Installed reconfigurable relay devices or systems may be configured to be controlled by one or more networks in a manner that enables them to operate efficiently and safely in a communications system, and which handles edge cases, such as non-operation of the reconfigurable relay system.

[0066] Can handle operations of multiple networks seeking to use a single reconfigurable relay device while establishing communication paths.

[0067] ● A unit for fast calculation of a radio frequency (RF) communication signal path from an access device to a terminal device via such a reconfigurable relay device may be provided.

[0068] Additional independent communication paths may be established, for example, two UEs located in the same direction as an access device may be served on the same frequency by beamforming directly towards one and beamforming towards the other via a reconfigurable relay, or beamforming towards the two UEs may be performed for each access device, with one using a path via a reconfigurable relay even if there is a direct line of sight (LoS) to that UE, again to avoid interference if the LoS path would affect the other UE and the relay-directed path would not.

[0069] Thus, newly installed reconfigurable relay systems can be registered so that if the formal registration process for the reconfigurable relay device is not available, the network or access device has the ability to command them to the desired state, including a discovery method. This allows the network or its access device to discover, establish and conduct ongoing control of completely passive reconfigurable relay devices. In addition, competition for control of purely passive reconfigurable relay devices is allowed between different networks and / or network operators. Even when the reconfigurable relay device is formally registered (by itself or its owner) in the database, the access device may need to discover or attempt the reconfigurable relay device if the reconfigurable relay device is reachable from the access device and whether it can help establish a useful communication path to the terminal device.

[0070] In addition, given that an access device (e.g., a base station) provides a possibly large number of beamforming directions, only some of the beamforming directions interact with a reconfigurable relay device, and there may be a very large number of states for the reconfigurable relay device, most of which result in no communication path to the terminal device, or there may be a very large number of individual elements in the reconfigurable relay device, making it infeasible to check through each element, and considering that any communication path to the terminal device includes both a backhaul link and an access link, which are typically independent of each other, the proposed solution provides an optimal method for finding a communication path to the UE via the reconfigurable relay device.

[0071] Additionally, queries and commands to the reconfigurable relay system may be formatted and sent to support their use in communications with end users, where the command / query communications meet security and acceptability requirements (e.g., the network has appropriate priority and authorization to use the reconfigurable relay device, if desired).

[0072] Furthermore, the proposed system can also be applied to outdoor and indoor environments. A possible scenario could be the improvement of connectivity outdoors, for example, in urban scenarios where the reception quality may not be as good as expected due to buildings, cars, etc. In this case, the network operator uses RIS installed in urban environments (e.g., in building facades, billboards, etc.) to improve network connectivity and services.

[0073] In addition, the proposed system can be applied to scenarios where the RRD is mobile and can travel with multiple terminal devices. The RRD can provide a reliable link to the terminal devices via an access channel and can connect them to the network via a backhaul channel. In this case, the condition of poor reception quality may be due to the backhaul channel rather than the access channel.

[0074] According to a first option that can be combined with any of the first to sixth aspects described above, a reconfigurable relay device can be searched in a relay installation database (e.g., by a registration controller), and a required registration method can be queried from the relay installation database or the reconfigurable relay device, or the reconfigurable relay device can be discovered using automatic discovery in a local method in which a local transmission path is annotated with a variable attribute. Therefore, path establishment can be adapted to a new network configuration to ensure an optimal communication path.

[0075] According to a second option which can be combined with the first option or any of the first to sixth aspects above, path establishment can be configured to apply transmission modeling within a local radio transmission model of the local environment to search for a suitable beam path, or use the results of previous beam directions plus relay states and UE positions stored in a database, or use an artificial intelligence model to learn the relationship or association between beam settings and parameters, the relay states of nearby reconfigurable relay devices and / or UE positions as input parameters and the link quality and / or performance of the target terminal device as output parameters. Therefore, a communication path including a related reconfigurable relay system can be planned, thereby avoiding an exhaustive real-world search through beam directions and relay states of access devices.

[0076] According to a third option which can be combined with the first or second option or any of the first to sixth aspects above, a redirection pattern of at least one beam applied to a wireless communication path can be controlled by using a scheduling request. Thus, scheduling considerations for future configuration states of a reconfigurable relay device can be added to the control action.

[0077] According to the fourth option which can be combined with any of the first to third options or any of the first to sixth aspects above, a timing advance can be applied in path establishment to compensate for a longer transmission path length via a reconfigurable relay device. This measure ensures that the reception time at the target terminal device can be appropriately controlled.

[0078] According to the fifth option which can be combined with any one of the first to fourth options or any of the first to sixth aspects above, the reconfigurable relay device can be queried to determine the current configuration state. Thus, the current redirection mode of the reconfigurable relay device can be considered in the path planning and establishment process.

[0079] According to the sixth option which can be combined with any of the first to fifth options or any of the first to sixth aspects above, the reconfigurable relay device can be a reconfigurable smart surface or other switchable metamaterial surface or smart repeater. Therefore, the switchable metamaterial surface and / or the reconfigurable smart surface can be combined with the smart repeater, or they can be selected to achieve an optimized network environment.

[0080] According to a seventh option that can be combined with any of the first to sixth options or any of the first to sixth aspects above, the reconfigurable relay device may include metadata, the metadata including at least one of the following: information required for deriving the capabilities of the reconfigurable relay device and its control through the network, location and / or orientation information, a configuration state set, a default configuration state, a reconfiguration speed, an authentication, control and query method, and a network control prioritization process. This option improves the efficiency of path planning and establishment by providing various initial information.

[0081] According to the eighth option which can be combined with any of the first to seventh options or any of the first to sixth aspects above, the reconfigurable relay device may include current information data, which includes at least one of the following: a current relay state indicating a currently set configuration state, a current controller priority parameter (e.g., a priority number) set as the priority of the current controller, a first flag indicating whether the current relay state is currently being commanded, a timer value indicating how long the current relay state has been commanded, and a second flag indicating an operating state. This option improves the efficiency of path planning and establishment by providing enhanced information about the current state of the reconfigurable relay device. For example, it can be determined whether a registered reconfigurable relay device is no longer functional so that it can be removed from a possible communication path with a terminal user UE.

[0082] According to the ninth option which can be combined with any of the first to eighth options or any of the first to sixth aspects above, the reconfigurable relay device may include at least one sensor for obtaining the position and / or orientation of the reconfigurable relay device. Thereby, the reconfigurable relay device can obtain direct information about its position and / or orientation, which can be signaled to a database, or (directly / indirectly) to a control access device which can use it for path planning.

[0083] According to the tenth option which can be combined with any of the first to ninth options or any of the first to sixth aspects above, the reconfigurable relay device may include a network usage log storing information about the usage time of the relay device. The log information can be used to derive usage information for evaluating the efficiency and / or appropriate placement of the reconfigurable relay device.

[0084] According to the eleventh option which can be combined with any of the first to tenth options or any of the first to sixth aspects above, the reconfigurable relay device may include a priority list for storing priorities of networks or devices that control the reconfigurable relay device, wherein the reconfigurable relay device is configured to compare the new priority of the new remote controller or the new controlled network with the current priority of the current remote controller or the currently controlled network, and if the new priority is higher, the reconfigurable relay device stops being controlled by the current remote controller or the current network, and allows control by the new remote controller or the new network. This provides the advantage that priority considerations can be included in path planning and scheduling based on the urgency or importance of the communication path. In addition, the network prioritization scheme can be used to prevent deadlock in the control of the reconfigurable relay device by multiple competing users.

[0085] According to a twelfth option that can be combined with any of the first to eleventh options or any of the first to sixth aspects above, the reconfigurable relay device may include a scheduler for scheduling configuration states requested by one or more networks or devices and for determining whether the requested configuration states are acceptable. Therefore, multiple networks and / or access devices can use the reconfigurable relay device in parallel, and the total transmission time can be reduced by scheduling the same configuration states in the same time period. In addition, transmissions can be planned in advance (e.g., cyclic transmissions), or, for example, in the case where new data for transmission is expected soon, a pre-scheduled time slot for RIS can be faster than attempting to negotiate RIS at the time of the next transmission.

[0086] According to the thirteenth option which can be combined with any of the first to twelfth options or any of the first to sixth aspects above, the reconfigurable relay device may include means for observing the quality of signals passing through or across it, wherein a quality report may be prepared and delivered to the access device.

[0087] Note that the above-mentioned apparatus may be implemented based on a discrete hardware circuit system having discrete hardware components, an integrated chip or a chip module arrangement, or based on a signal processing device or chip controlled by a software routine or program stored in a memory, written on a computer-readable medium or downloaded from a network such as the Internet.

[0088] It should be understood that the method according to claim 1, claim 2, claim 16, claim 21, the secondary station according to claim 20, claim 28, the primary station according to claim 29, and the wireless network according to claim 31 can have similar and / or identical preferred embodiments, in particular as defined in the dependent claims.

[0089] It shall be understood that a preferred embodiment of the invention can also be any combination of the dependent claims or the above embodiments with the respective independent claim.

[0090] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

[0091] In the following figures:

[0092] Figure 1 schematically illustrates a summary architecture of a RIS registration and control system according to various embodiments;

[0093] Figure 2 Schematically illustrates a flow chart of a RIS registration and control method according to various embodiments;

[0094] Figure 3 Schematically illustrates the RIS discovery and registration process according to an embodiment with a RIS installation database;

[0095] Figure 4 Schematically illustrates the RIS discovery and registration process according to an embodiment with a RIS request for registration;

[0096] Figure 5 Schematically illustrates the RIS discovery and registration process according to an embodiment with automatic discovery;

[0097] Figure 6 Schematically illustrates the RIS query and command process according to an embodiment;

[0098] Figure 7 Schematically illustrates a network control prioritization process according to an embodiment;

[0099] Figure 8 schematically illustrates a communication path establishment process according to an embodiment with exhaustive search;

[0100] Fig. 9 Schematically illustrates a communication path establishment process according to an embodiment with a beam path memory;

[0101] Fig.10 Schematically illustrates a fault identification process according to an embodiment;

[0102] Fig.11 schematically illustrates a flow chart of a process for RIS-enabled communications according to various embodiments;

[0103] Fig.12 schematically illustrates a first example of an improved beam steering process according to an embodiment; and

[0104] Fig.13 A second example of an improved beam steering process according to an embodiment is schematically illustrated.

[0105] Fig.14 An example of the beam steering process and management of CSI estimation according to an embodiment is schematically illustrated. DETAILED DESCRIPTION

[0106] An embodiment of the present invention is now described based on a 5G cellular network environment.

[0107] Throughout this disclosure, the abbreviation "gNB" (5G terminology) or "BS" (Base Station) is intended to represent an access device such as a cellular base station or a WiFi access point. A gNB can consist of a centralized control plane unit (gNB-CU-CP), multiple centralized user plane units (gNB-CU-Up) and / or multiple distributed units (gNB-Du). The gNB is part of the Radio Access Network (RAN) that provides an interface to functions in the Core Network (CN). The RAN is part of a wireless communication network. It implements the Radio Access Technology (RAT). Conceptually, it resides between communication devices such as mobile phones, computers or any remotely controlled machines and provides a connection to their CN. The CN is the core part of the communication network that provides many services to customers interconnected via the RAN. More specifically, it directs the communication flow through the communication network and possibly other networks.

[0108] Furthermore, the terms "base station" (BS) and "network" are often used as synonyms in this disclosure. This means that, for example, when it is written that "network" performs a certain operation, it can be performed by the CN function of the cellular network, or by a specific base station that is part of such a cellular network, and vice versa. It can also mean that part of the function is performed by part of the function of the cellular network and the base station.

[0109] Additionally, the term "verify" is intended to refer to a process or action that may include typical information technology (IT) security operations such as decryption, signature checking, authentication, authorization, and the like.

[0110] A network controlled repeater (NCR), for which the term "intelligent repeater" is used as a synonym in this disclosure, comprises at least a first pair of RF amplifiers, one operating in the uplink direction (terminal device to network) and the other operating in the downlink direction (network to terminal device), which operate under local control of an NCR-MT (NCR mobile terminal) linked to the network via a control link. This provides the network with the ability to control the behavior of the RF amplifiers, e.g., whether they are off or on, operating gain, etc. Typically, the network will control the amplifiers so that signals sent from the network across the backhaul link are transparently relayed across the access link to the terminal device, and vice versa.

[0111] The NCR also includes an antenna system on the access link for transmission and reception to and from the terminal devices, another antenna system on the backhaul link for transmission and reception to and from the network, and a third antenna system on the control link for transmission and reception between the NCR-MT and the network. The antenna systems on the backhaul link and the control link can be shared, but are typically independent systems that can operate on different frequency bands. All antenna systems can possess some directional capabilities, which are again intended to be under the control of the network. In this regard, the control link can behave in a manner similar to that between the network and a directly connected UE. The access link can behave as an extension of the network's own directional antenna capabilities transmitted to the NCR location. In both cases, information for appropriate control of the antenna radiation direction can be obtained from the channel state information (CSI) signals exchanged between the network and the NCR-MT or the network and each terminal device.

[0112] For the backhaul link, there is no equivalent to CSI signaling because the NCR operates transparently on the signals on the backhaul and access paths. This means that there is no direct way to measure the quality of the backhaul link and it is not easy to determine the most appropriate settings. Since it operates in tandem with the access link, problems with the backhaul link potentially affect all terminal devices using the NCR. In some cases, where the backhaul link and the control link can share resources, the backhaul link can default to the settings used by the control link. In other cases where this is not possible, other methods need to be used. The purpose of the present disclosure is to describe such methods.

[0113] A wide range of names have been given to (large area) surfaces that can passively redirect radio waves impinging on them, but where these reflective or transmissive properties can be changed and / or switched and / or reconfigured to result in different passive behaviors depending on the "state" they have been set to. These names include intelligent reflective surfaces (IRS), reconfigurable smart surfaces (RIS), large intelligent surfaces (LIS), reconfigurable metasurfaces (RM), programmable metasurfaces (PM), large intelligent metasurfaces (LIM), smart reflective arrays (SRA), software defined metasurfaces (SDM), software defined surfaces (SDS), passive intelligent surfaces (PIS), and passive intelligent mirrors (PIM).

[0114] These surfaces can switch between different states, each of which reflects or transmits radio waves in a different way. The differences that exist within these types of surfaces are that some have an inherent ability to determine signal strength, for example, they include receiver as well as reflector / transmitter capabilities, and can therefore act as independent "relay-like" systems, for example performing their own beam path search (albeit with reflected / transmitted signals originating elsewhere). Their similarity to relays enables them to be integrated into communication standards (e.g., cellular standards).

[0115] Such switchable metamaterial surfaces offer many possibilities for improving the communication path between a base station or other type of access equipment and a terminal device (eg, UE).

[0116] In the following, the term "reconfigurable smart surface" or "RIS" will be used to refer to any of the above surface types. In an embodiment, it can be assumed that the arrays of RIS are completely passive, that is, they have no inherent radio sensing capabilities and therefore cannot perform beam searching or similar functions by themselves, but can be defined by the switching state when commanded by an external controller, and it is the responsibility of the external controller to determine the appropriate state to set the RIS. The RIS can also be partially passive and / or partially active (e.g., including some radio capabilities, signal processing capabilities, sensors, motors for changing the orientation of individual sub-panels / sub-elements of the RIS). Note that throughout this disclosure, only those blocks, components and / or devices related to the proposed data distribution functionality are shown in the accompanying drawings. For the sake of brevity, other blocks are omitted. In addition, blocks designated by the same reference numerals are intended to have the same or at least similar functions, so that their functions are not described later.

[0117] In many cases, a RIS can be used where a smart repeater / NCR can be used, and vice versa. The problem of control of the backhaul link is similar for both the RIS and the smart repeater / NCR. Hereinafter, the terms RIS and smart repeater / NCR may be used interchangeably (unless specific indications apply only to smart repeaters / NCRs or RIS). The term "reconfigurable relay device (RRD)" is used to represent a RIS and / or a smart repeater / NCR or any other device that performs the same function.

[0118] The following embodiments allow for enhanced link quality control of wireless communications involving an access device (eg, a base station (BS)), an RRD, and a terminal device (eg, a UE).

[0119] More specifically, RRDs may be seamlessly integrated into 5G networks via maintenance of a BS (e.g., a gNB in ​​5G terminology) of a 3D transmission database for a local area, which may include buildings, objects, neighboring BSs, and may include all known RISs and their properties (including the operation of the RRDs and the units that control them). The resulting 3D radio propagation model may be used together with some limited local searches to select a communication channel, including both the BS beam direction and the state of the RRDs controlled by the network and / or BS.

[0120] During use, the BS performs an analysis of the desired communication, which may depend on the estimated location of the user (of the user's UE), and predictions from its 3D radio propagation model (e.g., based on the above-mentioned 3D transmission database). The BS may use its beamforming capabilities and may actively switch / control the behavior of the RRD under its control to maximize communication quality and / or throughput, preferably while minimizing transmission power levels.

[0121] The following description uses RIS as a representative example of RRD. It should be understood that a smart repeater / NCR can be used instead of RIS (unless specifically indicated to apply only to smart repeaters / NCR or RIS), and therefore, the description also covers the operation of smart repeaters / NCRs.

[0122] RIS control interface and architecture

[0123] The following embodiments cover a registration procedure, a RIS query and command procedure, a communication path establishment method from a BS to a UE via a RIS, a network control prioritization procedure on a command initiator (ie, a controller), and a RIS failure identification procedure.

[0124] Figure 1 Schematically illustrates a summarized architecture of a RIS registration and control system (with optional elements and functionality) according to various embodiments.

[0125] The proposed system for RIS-enabled communication includes a base station (BS) 10, at least one reconfigurable relay device (eg, a reconfigurable smart surface (RIS) 20, and a user's terminal equipment (UE) 40).

[0126] The RIS control base station 10 includes RF communication capabilities (RF-COM) 150 according to the communication standard involved (e.g., 5G NR) and a network to RIS communication system (NW-RIS-COM) 110 (also called a state controller), as a unit for sending and receiving communications to and from RIS 20, which can simply communicate with RIS 20 using its standard communication facilities (e.g., based on the F1-C interface) or can include messages sent to a specified Internet address. It includes a BS to RIS sending and receiving system (NW-RIS-TRX) 1110, RIS query and command capabilities (RIS-C / Q) 1120, and command / query formatting 1130 for the verification process (C / QF).

[0127] The UE 40 includes an RF communication capability (RF-COM) 410 for enabling communication with the BS 10 according to the communication standard involved (e.g., 5G NR).

[0128] In addition, BS 10 includes an optional RIS database (RIS-DB) 120, which contains a list of local RISs and their metadata and optionally the BS beam direction to aim at each RIS. It may store only the beam direction to aim at each specific RIS. Optionally, the metadata from RIS 20 may be extended to include various aspects of its performance determined by the network or BS 10, such as its optimal beam direction, availability, utility in communications, performance variations according to weather and time of year, etc.

[0129] The RIS database 120 may be divided into RIS information, which is generally network-specific to many local BSs (e.g., the location of the RIS or the capabilities of the RIS) and information specific to an individual BS (e.g., whether a particular UE can be reached via the RIS controlled by that BS). For example, access to a particular RIS may be negotiated for a network operator by any of its BSs, and some information for that RIS may be common to all BSs. However, the ability to use a particular RIS may differ between individual BSs, e.g., the RIS may become ambiguous for one BS but not another.

[0130] In addition, BS 10 includes a communication path including a RIS planning module (CP / RIS-PM) 130, which may include:

[0131] An optional Local Radio Transmission Model (LRTM) 1310 of its local environment, which includes the presence, location and behavior of any RIS that can be used to identify the correct configuration of BS beam directions, the selection of a RIS and the RIS state to communicate with the UE at a defined location. Optionally, the performance of the RIS in the Local Radio Transmission Model 1310 can be determined based on additional RIS database components calculated (such as performance according to weather and time of year).

[0132] An optional database (L / RIS-S-DB) 1320 for storing UE locations, RIS metadata (e.g., RIS capabilities, RIS location, and / or RIS status), and linking a particular RIS, the status settings for that RIS, and the locations of UEs that successfully communicated with the BS 10 using that RIS and RIS status (given one or more of the UE location, the identity and location of a RIS (or beam direction to that RIS), and / or RIS status associated with past communications to that UE location via the RIS).

[0133] - Optional RIS beam searching capability (RIS-BS) 1330, which may provide a local or global search through the state of the RIS for optimal communication with the UE (whereby the local state may be derived or retrieved from the RIS state topology map included in the RIS metadata).

[0134] In addition, the BS 10 includes a RIS registration capability (RIS-REG) 140, also referred to as a registration controller, including at least one of the following:

[0135] Optional RIS Installation Database Query (RIS-I-DB-Q) function 1410, which provides the ability to query the RIS Installation Database (RIS-I-DB) 30 to determine new entries in the RIS Installation Database 30, which can be used by the RIS control network or BS 10 to return the elements needed to negotiate access to the RIS.

[0136] Optional RIS Registration Request Response (RIS-REG-REQ-RES) function 1420, which provides the ability to respond to communications from the RIS to establish registration entries as part of the RIS registration process. In the case where the RIS is associated with a specific operator,

[0137] This may also be hosted on a network (eg, the Internet) or in a specific operator network.

[0138] RIS Registration Processing Capability (RIS-REG-P) 1430, which provides the ability to negotiate access to the RIS, including at least one of: negotiating a unit of authentication, obtaining control and query access, agreeing on a price and pricing method (if any), and obtaining access to RIS metadata 220 and / or entering it into the RIS database 120.

[0139] Optional beam direction and / or UE position log (BD / UELOG) 1440, which associates the beam direction with the position of all UEs it has communicated with over a period of time (obtained during communication with UE 10). This log 1440 may be analyzed using beam direction and / or UE position log analysis to identify beam directions with large variations in UE positions, consistent with the presence of RIS in that beam direction. In an example, the BS 10 may estimate the position of the UE for each UE as the BS 10 communicates with it. In another example, the self-reported UE position may be refined by additional estimates performed by the BS.

[0140] In addition, the RIS 20 may include at least one of the following components or functions:

[0141] i. A reconfigurable surface (REC-SF) 270 may be a multi-element electronically controllable surface that may be set to a plurality of configuration "states," each configuration "state" resulting in a different redirection pattern of radio waves at frequencies associated with communications. Such redirection may include at least one of the following:

[0142] Reflection with a given reflection angle;

[0143] ·transmission;

[0144] Focus or defocus;

[0145] Generation of multiple beams;

[0146] Refraction with a given refraction angle (this option is important to allow communications, for example inside buildings); and

[0147] Absorption (this option can be used to reduce noise and / or isolate a given environment).

[0148] Configuration states can be represented by a discrete number of state identifiers (e.g., State 1, State 2, State 3) or a set of signal characteristics as a representation of the redirection pattern (e.g., (desired) reflection angle, focal point, number of beams, absorption / damping factors, etc.).

[0149] The configuration state may also be the individual state of each element in a multi-element RIS, which may be represented as a bitmap (e.g., identifying the on / off state of each element) or a multi-dimensional array (e.g., identifying the phase shift, absorption, focusing information, angle information, etc. of each element). Elements within the RIS may be electronically controllable (to change their individual states and / or desired properties), but may also be physically controlled (e.g., by motors to physically control the angle of the RIS). To control optical communications, the RIS may also have elements consisting of lenses, where focus, opacity, curvature, polarization / filter state, and reflection angle may be (individually) controlled.

[0150] These configuration states can be controlled by an access device (e.g., a base station) of the wireless network by indicating a desired state, whereby the RIS reconfigures elements of the RIS in a way to achieve the desired state, or by sending control information with detailed (re)configuration parameters (e.g., individually for each element in a multi-element RIS) from the access device to the RIS to reconfigure the RIS to its desired state.

[0151] ii.RIS control module (RIS-CM) 260 is configured to set the state of the reconfigurable surface 270 when commanded, for example, by the RIS communication module 110 of the BS 10. The RIS control module 260 can store the current state of the reconfigurable surface 270 currently set to the RIS state. In addition, the RIS control module 260 can include an optional state cycle (ST-CYC) capability or function 2610 to perform a state cycle during initial power-up, whereby it periodically switches its state to a random wide range of different states. This behavior can be suppressed when the RIS 20 is successfully registered with one or more networks and / or controlled by an access device, or this function can continue to be performed when the RIS 20 is not commanded to prevent the RIS 20 from being used as a passive surface by the BS. The goal can be to prevent others (e.g., BSs from network operators that do not have a usage agreement with the RIS owner) from using it as a passive surface. Another option is that the RIS 20 keeps changing the state, and only when the network decides, it configures its state according to the needs of the network. Alternatively, the network controlling RIS 20 (e.g., BS 10) may be aware of the schedule for RIS states, e.g., RIS 20 provides BS 10 with its schedule for the time periods when BS 10 has leased RIS 20, and uses it to pick the correct communication time slot to use RIS when it is in a particular desired state.

[0152] iii. RIS metadata (RIS-MD) 220, which includes information about the RIS (e.g., capabilities for exporting the RIS and its control over the network). This includes at least one of the following:

[0153] • Identification information (eg, this information may be entered by the installer).

[0154] Position and orientation (e.g., this information may be input by an installer of the RIS 20 or a RIS sensor (RIS-S) 250 which determines the position and 3D orientation and may be automatically communicated, e.g., during a registration process);

[0155] a set of configuration states (e.g., a discrete or possibly continuous set of state values ​​that may be represented as the way an incoming radio wave onto a surface at a particular angle is converted into an outgoing radio wave, including direction, focus, etc.; the states may be organized into a topology (RIS state topology) that shows which states are "adjacent," i.e., given a result, such as beam direction, it

[0156] are most similar to enable a local search for the best communication path starting from the Start RIS state);

[0157] Default RIS state (e.g., the state that RIS 20 sets itself to when no state is commanded); RIS 20 will likely default to a particular state when not powered or when not commanded to assume some other state (these states may not be the same); the network may need to know this default state because it may be in this state before the network commands it to be in some state optimized for communication (unless RIS 20 is set to perform "state cycling" to prevent it from acting as a passive surface, in which case it will

[0158] has a random and changing state);

[0159] The speed of reconfiguration surface switching (RIS may be able to switch their states as quickly as possible, because slow switching will interfere with the ability of the BS to quickly establish high bandwidth, reliably communicate with UEs (especially mobile UEs), use the RIS and of course search for communication paths by cycling through the states of the RIS; the speed of state switching of the RIS 20 may indicate the number of states that can be searched in a reasonable time if a communication path needs to be searched; or it may indicate solely the number of states that can be searched from one state command during operation

[0160] speed or duration to another state);

[0161] Authentication, control and query methods (e.g., control methods by which signals sent to surfaces set them to a specified state (which is a set of categorical values ​​or one of a small number of continuous values)); and / or authentication methods by which it can be determined that control signals sent to the RIS 20 will be sent by a valid originator; authentication methods can also ensure the freshness of commands; during the registration process, some form of command verification can be established, for example, security keys should be exchanged so that the RIS 20 can determine in the future that its execution

[0162] any command sent to it actually comes from an authenticated source with permission to command it ;);

[0163] Network control prioritization process (e.g., the priority of controls assigned to the RIS based on network operator or BS identification); and

[0164] Cost (e.g., if there is a cost associated with the control of the RIS 20 (which is charged by the owner of the RIS 20 to control the RIS

[0165] 20), this can be derived by the network, for example, in terms of quantity and scheduling (e.g., pay-per-use, fixed fee, time-based pricing, etc.).

[0166] Device type (e.g., reflective RIS (which allows the signal to be reflected to the UE on the same side of the base station (BS)), transmissive RIS

[0167] (which allows signals to penetrate the RIS to serve UEs on the opposite side of the BS) or a hybrid RIS (where the RIS has dual functionality of reflection and transmission), which may also include information about, for example, the number of separate sub-elements / panels, the materials used, the physical dimensions / size of the device.

[0168] capabilities (e.g., radio / communication capabilities, relay capabilities (e.g., support / compatibility with IAB relays, smart relays, ProSe relays), number / type of sensors, characteristics and (relative) positions of RIS elements, maximum / minimum reflection angles, supported and / or non-supported frequencies or frequency ranges, supported reflection angles, (number of) motors used to physically control the angles of the RIS and / or elements of the RIS and the degrees of freedom they allow.

[0169] In addition, RIS 20 includes a RIS communication module (RIS-COM) 210 that can receive commands and inquire and return results. RIS communication module 210 may include at least one of the following:

[0170] RIS transmit and receive system (RIS-TRX) 2110, which may use the same wireless communication system (e.g., 5G NR) as the RIS control network (e.g., BS 10), but may include sending and receiving messages via other wireless communication systems or via the Internet, connected locally using Wifi, Ethernet, Bluetooth, etc. In order to achieve seamless use of these RIS in the process of communicating with UE 40, the state handover command to be communicated to RIS 20 may be sent or routed via the same communication network whose BS is seeking to establish a communication path to UE 40. However, other units that communicate with RIS 20 may be used (e.g., via Internet Protocol, via a fixed Internet link, Wifi, Bluetooth, etc.), but delays may be introduced in the process of establishing communication with UE 40.

[0171] RIS Registration Capability (RIS-REG) 2130 is configured to establish the registration of RIS 20 in RIS installation database 30.

[0172] RIS Command / Query Authentication and Acceptance (RIS-CQE-V) capability 2120, which may include a verified network list (e.g., a list of networks or BSs that have been verified for controlling the RIS 20), an optional RIS network priority list (e.g., giving a negotiated priority number for each verified network), optional additional information required to accept commands / queries from networks (such as a "network blacklist"), and an optional capability to initiate registration with one or more networks (e.g., a RIS registration request capability).

[0173] In addition, RIS 20 includes RIS current information data (RIS-CID) 230, which may include a current RIS state, which may indicate the configuration state currently set for the reconfigurable surface 270; an optional current controller priority number, which is set to the priority number of the current controller (if not commanded, this flag may be set to zero (NULL)); an optional current commanded flag, which indicates whether the current state of the RIS 20 / reconfigurable surface 270 is currently being commanded (e.g., by another network / BS); an optional timer for a time period (e.g., a timer and a timer value, which indicates how long the current state has been commanded by the network); and a no-op flag (which is set to "false") if the RIS 20 is properly powered and is able to set its state to a command or "true" if the RIS 20 is currently unable to set its state to a commanded state.

[0174] Optionally, the RIS 20 may include a network usage log (NU-LOG) 240 that stores the total time each network / BS has used the RIS 20 / reconfigurable smart surface 270 in the last time period, and optionally, a complete list of the usage time and length of usage of the RIS 20 for each network during a defined time period.

[0175] As a further option, RIS 20 may include RIS sensors (RIS-S) 250, e.g., a collection of sensors that collect the position and orientation of reconfigurable surface 270. As an example, RIS 20 may include a GPS / GNSS module to determine its position and / or receive clock synchronization information, and may, for example, contain a gyroscope and / or a compass to determine its orientation.

[0176] Optionally, the system may include a published RIS installation database (RIS-I-DB) 30, in which details of all RIS installations and units requesting registration for them are stored, whose functions include:

[0177] i. A unit / function for entering a new RIS installation into the RIS installation database 30; and

[0178] ii. A unit / function for querying the RIS installation database 30 according to location and / or according to RIS type and / or according to RIS attributes.

[0179] Smart Repeater

[0180] In general, RF signal repeaters share many of the same properties as reflective smart surfaces, but use RF transmitter and RF receiver front ends to rebroadcast RF signals instead of using reflections of the signal to propagate the RF signal. However, one of the benefits of RIS is that the gNB can dynamically control the state of the RIS. In another embodiment, the smart repeater interface can be based on the proposed system and method.

[0181] An RF repeater is a device that "repeats" a signal received from an access device (e.g., a gNB) thereby extending its range. Preliminary evaluations indicate that performance improvements can be achieved by adding side control information (on / off, timing, spatial Tx / Rx), i.e., by making the RF repeater smarter. In this sense, a smart repeater may include not only the RF layer of an access device (e.g., a gNB), but also a PHY layer for the control plane and may, for example, include a communication module or UE similar to the RIS communication module 210 or RIS-UE 50 for sending and receiving information to the access device. The access device (e.g., gNB) may then direct the smart repeater using parameters such as timing configuration (UL / DL), beamforming or on / off.

[0182] It is expected that the steering capabilities of smart repeaters and RIS are similar. As described above, an access device (e.g., gNB) can command RIS to set a given reflection pattern for a given period of time. This is similar to configuring beamforming in a smart repeater. An access device (e.g., gNB) can control RIS for some time slots, which is similar to providing a given timing configuration to a smart repeater. In addition, RIS is turned off by default, so it only operates when an access device (e.g., gNB) is using it.

[0183] From this point of view, the embodiments in the present disclosure may also be implemented in a smart repeater or a combination of a RIS and a smart repeater. To this end, the RIS20 in the embodiments in the present disclosure may also be a smart repeater. Therefore, in the embodiments of the present disclosure, the term RIS20 may be replaced by the smart repeater 20. In the device architecture, the reconfigurable surface (REC-SF) 270 may be replaced by a transceiver including an RF receiver front end and an RF transmission front end coupled to one or more antennas, whereby the controllable state may include a state / setting for controlling the on / off state, beam steering (e.g., the number of beams, beam direction), transmission power, and / or the frequency and / or timing (e.g., configurable delay) of the transmitted RF signal, and whereby the redirection mode may include generating multiple beams, focusing or defocusing beams, directing beams at a specific angle (whereby the angle may be relative to a reference line or magnetic north, or the angle between an incoming beam and an outgoing beam (i.e., similar to a deflection / refraction angle)), amplifying incoming signals (e.g., by providing an amplification gain in a command), delaying signals (e.g., by providing a delay time or specific timing for an outgoing signal in a command). The transceiver may be the same as the RIS transmit and receive system (RIS-TRX) 2110, or may reuse / share components within the RISC-TRX 2110, or it may be a separate subsystem.

[0184] RIS Registration and Control Procedure

[0185] Figure 2 A flow chart of a RIS registration and control method according to various embodiments is schematically shown.

[0186] In the network registration (NWR) step S201, the network (eg, BS 10) registers the RIS 20 and determines all parameters required for its control, while the control is performed by authenticated and accepted commands and queries.

[0187] In a subsequent path determination (PD) step S202, the network / BS determines the best communication path with the UE (e.g., UE 40), including directing the path of the beamformed (directional) signal toward the RIS 20 and setting the RIS state so that the beam is correctly redirected toward the UE. If the LOS signal between the access device and the UE or between the RIS and the UE has deteriorated or experienced a drop (e.g., due to an obstacle) or has a signal strength peak (e.g., due to a signal reflected via the RIS), the network / BS may be triggered to communicate with the UE via the RIS and / or initiate a path determination step and / or configure / command the RIS. This may be discovered through measurement reports or CSI feedback from the UE and / or from the RIS (e.g., measurement reports or CSI feedback related to the link between the RIS and the UE). In a specific example, if the measurement report (e.g., through its RSRP feedback or UE RX-TX feedback) shows that the UE is moving in a certain direction, but adjusting the beam toward the UE does not improve or actually deteriorates the signal quality / strength, it may indicate that the UE is blocked by an obstacle. This may trigger the network / BS to trigger a local beam search or other communication / beam path establishment procedure (as described in other embodiments) to determine the RIS and / or the state of the RIS to establish a communication path to the UE via the RIS.

[0188] In the following state determination (SD) step S203, the network / BS queries the RIS 20 to determine its current state, including whether it is commanded by another network and optionally, what the priority level of the current command is.

[0189] Then, in a beam steering and state command (BD / SC) step S204, if the path found in step S202 is a path that achieves good quality communication, and the network / BS is able to command / control the RIS 20, the network / BS directs its beamforming (directional) signal toward the RIS 20 and commands the RIS 20 to the relevant state. This process can be repeated as the UE moves, or as large objects in the environment cause obstacles to the movement of the RF communication path.

[0190] Finally, in a check (CHK) step S205, the network / BS may routinely check whether the RIS in its RIS database 120 remains operational.

[0191] Thus, newly installed RIS systems can be registered so that the network / BS has the ability to command them to a desired state, including a discovery method if the formal registration process for the RIS is not available. This provides the ability to quickly plan communication paths that include relevant RIS systems, avoiding an exhaustive real-world search through BS beam directions and RIS states. In addition, registered RISs that are no longer functional can be removed from possible communication paths with end users.

[0192] Figure 5 The RIS discovery and registration process according to an embodiment with automatic discovery of the RIS 20 in a local approach is schematically illustrated.

[0193] When RIS 20 is installed and powered on but not yet registered with any network, the initial behavior of RIS control module (RIS-CM) 260 may be set to a state cycling (ST-CYC) function 2610 in which RIS 20 periodically changes its state to a state randomly selected between separate states.

[0194] Additionally, the owner of the RIS 20 can set the RIS 20 to activate the state cycling function 2610 when not controlled by a network / BS (rather than the default RIS state) in order to (for example) prevent any network from using the RIS 20 as a passive surface without appropriate payment or permission, which may otherwise be possible if the state is predictable.

[0195] When the RIS 20 is registered and controlled by at least one network, the RIS 20 can adopt the state commanded by the registered network. The RIS 20 can also operate a state cycling function 2610, whereby it randomly changes its state when it is not actively commanded to a state. In both cases, a beam directed to the RIS 20 from an unregistered BS will be redirected in different directions at different times.

[0196] The network (i.e., BS10) to which RIS20 is not currently registered or to which it is not currently actively commanding may use its beam direction / UE position log (LOG) 1442 analyzed by its beam direction / UE position log analysis (BD / UE) 1440 to note / determine that the beam path to certain end UE locations may change significantly when the BS beam is pointed at a particular direction. That is, a certain beam direction is associated with a log of end user / UE locations that change significantly at different times. Or, alternatively, it may be noted that a BS beam pointed in a particular direction gives a particular variable (e.g., intermittent and periodic) connectivity to a particular fixed UE. The analysis may indicate that RIS20 is present in that beam direction. The corresponding information stored in the beam direction / UE position log 1442 may have been obtained from the RF communication capability (RF-COM) 150 based on the beam pointing to the reconfigurable surface (REC-SF) 270 of RIS20 (e.g., based on a collection of measurement reports from a UE or from a RIS registered to BS10, which may include, for example, RSRP values ​​per beam / SSB index). Based on this information / analysis, the network (ie, BS 10 ) may decide which RIS to select and / or whether to register / connect to RIS 20 and / or decide to send commands / queries to RIS 20 .

[0197] Noting the location and / or beam direction of the newly identified RIS 20, the network may seek to establish a registration with the RIS 20 by a variety of methods, including searching in a database, sending a direct request using a wireless communication protocol (e.g., a discovery protocol), sending a communication to a company or individual located in the building, etc. Figure 5 In the example of , RIS registration capability (RIS-REG) 140 of BS 10 obtains a unique identifier 510 of RIS 20 (and optionally a method of requesting registration) from RIS installation database (RIS-I-DB) 30 based on, for example, the results of beam direction / UE position log analysis 1440.

[0198] Once the RIS registration method is obtained, the RIS metadata 220 of the RIS 20 may be provided to the BS 10 using a negotiation and verification process 520 between the RIS registration processing capability (RIS-REG-P) 1430 of the BS 10 and the RIS registration capability (RIS-REG) 2130 of the RIS 20. The RIS metadata 220 may then be entered into the RIS database 120 of the BS 10. If the RIS 20 includes RIS sensors (RIS-S) 310, the location and / or orientation of the RIS 20 may be collected from these sensors 310 and transmitted as part of the RIS metadata 220.

[0199] BS 10 can negotiate to use its RIS registration processing capability 1430 to control RIS 20 to obtain verification, priority of RIS use, and optionally payment price and / or scheduling of use of RIS 20. Once this negotiation is successfully concluded, the command / query verification process is agreed as described above. This is the verification process for subsequent commands or queries.

[0200] Actively search for communication paths via RIS

[0201] Given the large search space introduced into the beam search by one or more RISs with possible options for communicating with the UE, conventional beam search techniques that extend by commanding cycles through the state of the RIS may introduce significant delays. Therefore, an improved beam path determination (e.g., BS beam direction and RIS state) for communicating with the UE at a certain location is proposed. As previously described, the BS may be triggered to initiate path determination, for example, if the LOS signal between the access device and the UE or the signal between the RIS and the UE has deteriorated or experienced a drop (e.g., due to an obstacle) or has a signal strength peak (e.g., due to a signal reflected via the RIS). This may be discovered via measurement reports or CSI feedback from the UE or from the RIS. Additionally or alternatively, if the network / BS receives a message from / via the RIS that the UE has lost connectivity and / or may wish to communicate via the RIS, for example, a discovery message is received from the UE on a side link (as described in further embodiments), the network / BS may be triggered to initiate a path determination step.

[0202] The base station may perform a real-world active search for the best communication path to the UE by cycling through the states of the RIS (or using its elements at a time) and beam directions until it determines a RIS state that achieves good enough communication for its operating requirements. If the RIS has many possible states (or elements), such a search may not be fast enough to routinely establish communications. Therefore, use of this real-world search may be limited to the first few times the network uses the RIS, after which one of the other suggested procedures will be used.

[0203] Figure 8 The communication path establishment process according to an embodiment with a real-world exhaustive search is schematically illustrated.

[0204] The proposed beam path establishment process enables the network to determine the location of the UE 40, determine whether the RIS contains suitable information for communicating with the UE 40, determine the optimal state to which the RIS is set to assist in the communication, and determine whether the correct beamforming direction is to point directly at the UE 40, or to redirect to the passive surface of the UE 40 or the RIS, which is now set to the correct state to send / reflect the beam to the UE 40.

[0205] exist Figure 8 In an embodiment of the present invention, a beam search is proposed to support transport ray tracing modeling.

[0206] The network (e.g., BS 10) maintains a 3D local radio transmission model (LRTM) 1310 of the environment, including the effects of known RIS and its states, and uses this model to perform a fast simulation optimization process (e.g., by the Communication Path and RIS Planning Module (CP / RIS-P) 130) to determine the correct beam direction and RIS state selection to achieve optimal communication with a UE located at a specific location.

[0207] Once the model has found a suitable communication path, a small real-world local search can be performed, for example through the RIS beam searching capability (RIS-BS) 1330, to optimize the link.

[0208] The communication path and RIS planning module 130 provides the next RIS state (RIS-S) to the command / query format for verification (C / QF) function 1130, which generates a command for the next RIS state (C-RIS-S) and provides it to the network, to the RIS communication system (NW-RIS-COM) 110. The command is then sent to the RIS 20 and received by the RIS communication module (RIS-COM) 210, which verifies and forwards it to the RIS control module (RIS-CM) 260. The RIS control module 260 controls the state of the reconfigurable surface (REC-SF) 270 of the RIS 20 according to the received command, thereby modifying the reflection or refraction or redirection of the transmission beam from the BS 10 accordingly.

[0209] The signal strength (SS) or another quality parameter obtained, for example, by the RF communication capability (RF-COM) 150 and the location (L) of the UE 40 may then be used. UE ) and / or measurement reports and / or measurement reports / CSI feedback of RIS (e.g., a link between BS and RIS or a link between RIS and UE) to update the model. In addition, or as Figure 8In an alternative embodiment, the network selects a RIS state that enables wide angle scattering of incoming signals / beams and / or wide beams (or even omnidirectional signals) to be propagated by the RIS toward the UE 40. The UE 40 may receive such reflected signals and may perform measurements on the received reflected signals and report the measurements to the network / BS (either directly through a line of sight connection or through an indirect path via the RIS or other relay device). The UE 40 may also report its estimated location (e.g., obtained through other units such as GPS or TDOA measurements from nearby base stations). The RIS may perform measurement reporting on uplink signals received from the UE 40. The RIS state selected by the base station and commanded to the RIS may be selected in such a way as to reduce the width of the propagated signal / beam and therefore use a smaller beam towards the UE 40 and / or change the angle of the beam towards the UE, which may again report its measurements. By using a feedback loop to change the angle and / or further narrow the beam based on feedback / measurements from the UE 40, a suitable communication path between the BS 10 and the UE 40 via the RIS 20 may be determined.

[0210] Fig. 9 The communication path establishment process according to an embodiment with a beam path memory and limited local beam search is schematically illustrated.

[0211] The communication path and RIS planning module (CP / RIS-P) 130 of the BS 10 can remember the UE ) for UE 40 and stores it in the location / RIS state database (L / RIS-S-DB) 1320. This is similar to the method with 3D local radio transmission model 1310. Figure 8 The embodiments work similarly.

[0212] If in the past the model has calculated a path and the BS 10 gave good results using that path, it may be stored in the database 1320. Then, when a future UE is discovered near that location, the previous beam direction and state of the reconfigurable surface (REC-SF) 270 is retrieved and used, optionally with some further optimization (e.g. using local search in the RIS state) and updating of parameters for communicating with that location.

[0213] Performing a limited search for the best path in the real world, the results from past use of the RIS 20 have been stored, i.e., the RIS state used to communicate with a particular location. From this point on, it can initiate a limited local search process through the RIS state. Using the RIS State Topology Map (RIS-STM), a local search can be performed from the initially selected state.

[0214] The pilot uplink signal from UE 40 can be used to determine its position in space (L UE ).

[0215] If beamforming in that direction directly (not via RIS 20) is determined to be insufficient and a similar (but not necessarily the same) location has been served in the past by a (nearby) RIS (e.g., RIS 20), then the RIS state used to communicate with that location in the past is retrieved and the RIS state is set to that value while beamforming is performed at RIS 20.

[0216] Using the RIS state topology map for the RIS, which is stored in its RIS metadata (RIS-MD), the RIS metadata may be stored in the RIS database (RIS-DB) 120, such as in Figure 8 A local search through neighboring states is performed as described in the embodiments of FIG. 5 and a signal quality is determined (eg, based on signal strength (SS) or another quality parameter).

[0217] When sufficient signal quality has been achieved (eg, a predetermined threshold has been reached), the corresponding RIS state is used to communicate with the UE 40, and the RIS state and UE location (L UE ) may be stored in the location / RIS status database 1320 of the RIS 20. Flowchart for RIS-enabled communications

[0218] Fig.11 A flow chart of a process for RIS-enabled communications according to various embodiments is schematically illustrated.

[0219] The process is designed to enable the establishment and command of RIS within a radio communication system such as 5G / 5G-NR.

[0220] The initial RIS discovery and registration process (RIS-D / R) S1101 enables a newly set RIS to be registered with a network and authenticate the network with the RIS, thereby establishing properties of the RIS with the network and enabling the network to effectively command the status of the RIS.

[0221] This can be accomplished by a RIS installation database registration method, where the new RIS is looked up in the global RIS installation database and the registration method is retrieved, or by a RIS request registration method, where the RIS sends the communication to the local network when first switched and sends the registration method, or by an automatic discovery of the RIS registration in a local method, where the BS records the local transmission path with variable attributes associated with the RIS and registers the local transmission path by various means (such as, for example, in Figure 5 ) seek registration as explained in the embodiments of the present invention.

[0222] Then, in the RIS query and command process (RIS-Q / C) S1102, the network and / or BS specifies the command or query to be sent to the RIS using, for example, the RIS query and command capabilities, formats the command / query using, for example, the command / query formatting for the verification function, sends the command / query to the RIS using, for example, the network / BS to RIS sending and receiving system, and receives any response from the RIS sending and receiving system from the RIS using the network / BS. In addition, the RIS receives the transmitted query or command using the RIS communication module, checks whether the command / query is valid, and if the command / query will be accepted using the RIS command / query verification and acceptance function, and if the command is accepted, the RIS command module sets the reconfigurable surface of the RIS to the commanded state, or if the query is accepted, the RIS returns RIS current information data including the RIS state.

[0223] In the Network Control Prioritization Procedure (NC-PRIO) S1103 during Registration, the RIS stores the priority of the network commanding the RIS in the RIS network priority list in case of subsequent changes or dynamically having a command.

[0224] If the RIS is not currently commanded and a command is received from the network, it determines the priority of commanding the network and stores it as the current controller priority in the RIS current information data (eg, indicated by a number as an index in an ordered list), and then executes the command.

[0225] If the current command is RIS, it compares the priority of the new command network to the priority of the current command network (stored as the current controller priority), and if the new priority is higher, RIS stops the command from the previous network and allows the new network command.

[0226] Alternatively, even a low priority network may be given a minimum time period for its command, and changes in command are enabled only after this minimum command time is reached.

[0227] In the communication path establishment procedure (CP-EST) S1104, the network and / or BS seeks to establish a communication path with the UE, wherein the path may include one or more RISs (wherein the RIS database indicates that the RIS is operational and the network has command authority).

[0228] This can be achieved through an exhaustive search of beamforming directions and RIS states to find the best communication path to the UE, and when found, the BS points its beam to the RIS and commands the RIS to the correct state.

[0229] Or, as in Figure 8As indicated in the embodiments of , beam search supporting transmission ray tracing modeling can be applied, where transmission modeling within a local radio transmission model of the local environment is used to search for a suitable beam path (e.g., BS beam direction and RIS state), followed by fine-tuning using a local search among neighboring RIS states retrieved from the RIS state topology map. When found, the BS points its beam to the RIS and commands the RIS to the correct state.

[0230] As a further alternative, in Fig. 9 As indicated in the embodiment of , the result of the previous beam direction plus the RIS state and the UE position is stored in the position / RIS state database. For a new UE position, the database is searched for the nearest entry for that position, and if close enough, the stored settings for the BS beam direction and RIS state are used, and fine-tuned with a local RIS state search. When found, the BS points its beam to the RIS and commands the RIS to the correct state.

[0231] In the RIS fault identification (RIS-FR) process S1105, as in Fig.10 As indicated in the embodiments of the present invention, if the RIS returns an out-of-operation flag set to "true", or if the RIS does not return a response to a query sent to the RIS, or if the communication signal strength and / or other signal quality indicators indicate no actual change in the RIS state, the network and / or BS enters into its RIS database.

[0232] Optionally, a RIS having reliably determined the presence of an end-user UE in this way may report this to a database / gNB so that the gNB may leverage the capabilities of the RIS to now focus the gNB's beam on that UE.

[0233] Fig.12 A first example of an improved beam steering process according to an embodiment is schematically illustrated.

[0234] In a first example, the RIS-UE 50 announces its RIS capabilities (e.g., using information provided through ProSe / Side Link Model A discovery) so that the UE 40 with poor connectivity can discover it. Alternatively, the UE 40 with poor connectivity may attempt to discover the RIS-UE 50 or other RIS-UEs (e.g., using information provided through ProSe / Side Link Model B discovery). Once the RIS-UE 50 and the UE 40 have discovered each other, if authorized, the RIS-UE 50 and the UE 40 may establish a communication link, for example, via a PC5 interface, and they may also identify their specific directions (e.g., beam angles / paths) by pairing their beams. The RIS-UE 50 may then send this information (i.e., the beam direction is towards the UE 40) to the controlling gNB 10. The gNB 10 knows where the RIS 20 of the RIS-UE 50 is located and in which direction it must form its beam to reach it. In addition, gNB 10 now also knows the location of UE 40 relative to RIS-UE 50, because RIS-UE 50 reports the beam direction from RIS-UE 50 toward UE 40. Therefore, gNB 10 can determine the configuration of RIS 20 (e.g., reflection / refraction angle or redirection beam angle) to directly reach UE 40. This is in Fig.12 , where the RIS configuration refers to the reflection / refraction / redirection angles achieved, for example, by the orientation of RIS 20 in space.

[0235] Improved beam steering by providing SSB and RIS for synchronization and system information

[0236] Fig.13 An example of an improved beam steering process according to another embodiment is schematically illustrated.

[0237] In this example, the gNB 10 sends system information (SI) towards the RIS 20, where the system information can be similar to the synchronization signal of the physical broadcast channel (PBCH) used to broadcast basic system information within the cell of the cellular radio access network. In this case, the access device, the gNB, drives the RIS directly from the CU or through the DU in a way that the RIS appears to distribute its own synchronization signal. The system information may include the primary synchronization signal (PSS), the secondary synchronization signal (SSS), and the master information block (MIB) broadcast in the PBCH channel. In order to emulate different synchronization signal bursts or blocks (SSBs) used in 5G and broadcast in different directions through different beams, the gNB 10 sends such RIS SSBs towards the RIS 20.

[0238] For example, in Fig.13In FIG. 1 , gNB 10 has sent four RIS SSBs toward RIS 20 at times t0, t1, t2, and t3 using a single beam directed toward RIS 20. gNB 10 may change the RIS state synchronously with the time when the RIS SSBs arrive at RIS 20, so that the RIS SSBs are reflected / refracted / redirected in different directions, such as Fig.13 As shown, at time t0', the RIS SSB is broadcast using the highest beam direction, at time t1', the RIS SSB is broadcast using the second highest beam direction, at time t2', the RIS SSB is broadcast using the second lowest beam direction, and at time t3', the RIS SSB is broadcast using the lowest beam direction.

[0239] When UE 40 receives the RIS SSB, the UE measures Fig.13 The signal-to-noise ratio (SNR) shown in the time correlation graph on the right. The graph shows that the first SSB broadcast at time t0' has been received with the second lowest SNR, the second SSB broadcast at time t1' has been received with the highest SNR, the third SSB broadcast at time t2' has been received with the second highest SNR, and the fourth SSB broadcast at time t3' has been received with the lowest SNR. UE 40 can select the SSB with the highest SNR to establish a communication link with gNB 10 through RIS 20. This can be achieved by assigning a separate parameter (e.g., time or frequency or preamble or code) to each beam and using the parameter to specify the beam during the initial random access procedure.

[0240] In the example, gNB 10 may keep sending RIS SSBs toward RIS 20, and gNB 10 may keep switching RIS states accordingly to keep emulating synchronization signals. If UE 40 moves, UE 40 may inform gNB 10 about the received SNR of each RIS SSB, so that gNB 10 may adjust the RIS state accordingly to ensure a good connection between gNB 10 and UE 40 through RIS 20. Note that since SSBs before reflection / refraction / redirection will result in almost the same (uniform) SNR, while SSBs after reflection / refraction / redirection will exhibit a non-uniform SNR distribution, UE 40 may be able to receive the SNR before being reflected / refracted / redirected ( Fig.13 SSB is distinguished during reflection / refraction / redirection (time t0 '... t3 ').

[0241] In an example, system information associated with RIS 20 (e.g., MIB or system information block (SIB1)) may include information about the fact that the gNB 10 sent the signal via RIS 20. This may be, for example, a single bit that may be 0 or 1. System information associated with RIS 20 may also include information about the parent gNB 10 directing RIS 20, which may include, for example, the physical cell identity (PCI) of the parent node. UE 40 may use such information to decide whether to join / communicate through RIS 20.

[0242] Improve CSI and reduce interference when using RIS

[0243] In another embodiment, channel state information (CSI) may be enhanced. In wireless communications, CSI refers to known channel properties of a communication link. CSI describes how a signal propagates from a transmitter to a receiver and represents the combined effects of scattering, fading, and power attenuation with distance, for example, obtained through a channel estimation process. CSI enables transmission adaptation to current channel conditions, which may be critical for achieving reliable communications with high data rates in multi-antenna systems.

[0244] Therefore, CSI Reference Signal (CSI-RS) can be used when the gNB transmits towards the UE to understand the channel properties and how good (or bad) the communication link is. The gNB can transmit CSI-RS, and the UE receives these and reports their values. In an example, CSI-RS can be transmitted every two resource blocks (SSBs). CSI-RS can be periodic, semi-persistent, or aperiodic (e.g., transmitted in a downlink control information (DCI) message).

[0245] In an example, zero-power CSI-RS may be provided as time / frequency slots where the gNB informs the UE that nothing is being sent. These slots may be used by the UE for interference management. Based on the received signal, the UE may select the most appropriate precoding matrix for antenna steering of the gNB, for example by using a given codebook of precoding matrices. There may be two types of codebooks: type 1 is coarse (e.g., for a single user) and type 2 is wide (e.g., for a multi-user multiple-input multiple-output (MU-MIMO) system). In the uplink direction, CSI may not be needed, as the gNB may track the quality of the received signal and instruct the UE accordingly.

[0246] As an alternative, a Sounding Reference Signal (SRS) may be used in this embodiment instead of CSI-RS. SRS is a reference signal sent by the UE in the uplink direction and is used by the gNB to estimate the uplink channel quality over a wider bandwidth, for example for scheduling purposes.

[0247] In case of RIS, the gNB may be interested in knowing the channels going to the UE via RIS.

[0248] In an example, when the UE is connected via RIS, an increased number of time slots (e.g., n) may be allocated for sending CSI-RS. For example, n=3 time slots. Although the reference signal may be the same at the transmission time of all n time slots, the gNB may control the RIS in such a way that the RIS has slightly different reflection / refraction / redirection RIS coefficients in those n time slots. For example, for n=3, the first time slot may use the reflection / refraction / redirection RIS coefficients and gNB-RIS beamforming that are currently considered optimal, and for the other two time slots, slightly different reflection / refraction / redirection RIS coefficients and / or gNB-RIS beamforming may be used. The goal may be that the UE may help the gNB identify the direction in which the RIS should be steered (i.e., which reflection / refraction / redirection RIS coefficients) in order to maintain a good connection and / or how the gNB beam should be steered towards the RIS.

[0249] The above process can be done for each resource block, or the configuration of the beam / RIS can be slightly adapted to the CSI-RS sent in different resource blocks.

[0250] Estimate the quality of the backhaul link independently of the access link

[0251] Fig.14 A network is schematically shown including a gNB 10 that communicates with a control module (RIS-CM 260) of the RIS 20 (via a control link between the NW-RIS-COM 110 at the gNB and the RIS-COM 210 at the RIS) and with one or more UEs 40 (via a backhaul link between the RF-COM 150 at the gNB and the RIS-FS 270 and via an access link between the RIB-FS and the RF-COM 410 of each UE).

[0252] When the gNB 10 communicates with the UE 40 via the RIS 20, the path passes through two links (the backhaul link and the access link), but only a set of CSI feedback covering both links is received from the UE. In the case of poor link quality, it may not be clear which link is the cause and should be adjusted. A unit that estimates the backhaul link quality independently of the access link to each UE is needed.

[0253] In some scenarios, the backhaul link and the control link operate in the same operating frequency band. Therefore, in a first embodiment, the backhaul link shares the antenna array used by the control link between the gNB and the RIS control module (RIS-CM) 260. The shared beam is then steered based on the CSI conversation between the gNB and the RIS-CM. When the gNB wants to communicate with a UE over RIS, the gNB allocates appropriate communication resources for the UE and establishes a CSI conversation with it to steer the access beam. Since the backhaul link is managed independently via the RIB-CM CSI conversation, the gNB can then consider the contribution of the backhaul link by assuming that the backhaul link is negligible. This may be appropriate if the CSI conversation with the RIS-CM reports a good channel or at least a channel with significantly better performance than the performance reported by the UE CSI conversation.

[0254] In this first embodiment, the fact is exploited that the performance of the backhaul link is known from the RIS-CM CSI dialogue. Thus, in the uplink direction from the UE, the gNB can compensate for the backhaul by equalizing the received signal based on, for example, readings from the CSI signal sent by the RIM-CM to the gNB over the control link. This can provide some additional margin against link degradations.

[0255] In case the same frequency band is used for uplink and downlink, as in TDD mode, for example, the gNB can also pre-equalize the downlink signal, which means that the UE receives a signal that is essentially only degraded by the access link.

[0256] The scenarios described in the foregoing embodiments are restrictive. There is interest in being able to support multi-band repeater operation without the need for a multi-band link to the RIS-CM 260. There may also be applications where, despite sharing the same frequency band, the RIB-FS 270 and RIB-CM are served by different transmit / receive points or different gNBs, and therefore different beams are required. Therefore, in a second embodiment, the fact is exploited that the backhaul link can be shared by many UEs, each with its own access link. If the backhaul link does not have good quality, the same channel degradation will be reflected in the CSI information from all UEs. This provides an indication to the base station that the failure is in the backhaul link rather than the access link.

[0257] If it can be assumed that the backhaul link is of good quality, the CSI information will say more about the access link, so that to a good approximation the contribution of the backhaul link to the overall link quality can be neglected. This may be the case, for example, if both the repeater and the base station are in fixed locations. In other cases, such as when the repeater is moving, or when the backhaul link needs to be established first, it cannot be assumed that the backhaul is of good quality, and some means of deriving the quality is necessary.

[0258] As an example of how this may work, for the downlink, UEs 40-1, 40-2, 40-3, 40-4 all return CSI feedback in the form of a four-bit CSI index, which indicates the modulation and code rate that the UE believes it can successfully demodulate. Low numbers indicate a poor channel (where 0 indicates no ability to demodulate the data) and higher numbers correspond to higher quality channels. Assuming the UEs all have similar demodulation capabilities, the different numbers can provide a measure of the relative performance of the backhaul link and the access link, and using a simple heuristic, the gNB can make a decision about which beam to adjust. For example, given that the relay provides good service to UEs outside the direct range of the gNB, uniformly low values ​​returned indicate a problem with the backhaul. Conversely, if any UE reports a good quality channel, the backhaul must also be good, and for the other UEs, the problem is with the access link. Therefore, a simple approach is to take the maximum quality reported by the UE as the quality of the backhaul. When the UEs use different CQI tables, the backhaul can be assigned the quality corresponding to the highest efficiency reported. If this falls below a threshold, the backhaul is adjusted; if not, the access link is adjusted.

[0259] Depending on the precise scenario, the changes will suggest themselves. For example, if the reported link quality is variable, suggesting mobility, then if there is no correlation between the changes from different UEs, then the backhaul link can be assumed to be stable, and again, the highest reading in a given period can be considered to indicate the quality of the backhaul link. On the other hand, if the changes have a strong correlation component, then the implication is that the backhaul link is suffering from problems due to mobility or some other reason.

[0260] A similar approach can be taken for the uplink as for the CSI signals sent from the UE. By assigning a quality index similar to the CSI index returned by the UE, the gNB can develop a comparative measurement of the uplink channel and using similar heuristics can determine whether to adjust the backhaul or a separate access link.

[0261] The previous embodiments relied on the presence of many UEs. The third embodiment addresses the case when only one UE is active or when the base station needs to steer both the backhaul link and the access link based on feedback from a single UE. If a single UE is involved, no comparison may be performed to determine the backhaul channel state separately from the access link. This is also true if the number of UEs is greater than 1, but still not sufficient for a meaningful comparison.

[0262] In a first embodiment, the base station uses the CSI information to first adjust the access downlink to obtain the best quality. If the quality is still insufficient (i.e., the CSI information still reports low quality), it uses the CSI information to adjust the backhaul link. This assumes that the access link changes frequently and may therefore be the cause of any changes in the overall link quality. In addition, the UE adjusts the access uplink to its best capabilities, and anything it cannot resolve may indicate a problem in the backhaul. At the same time, the backhaul link changes relatively slowly, and changes should be made as a last resort. The algorithm can be modified to adapt to different situations. For example, in a vehicle scenario, it can be assumed that the backhaul will change frequently, while the access link will be more stable.

[0263] In a second embodiment, the base station 10 independently adjusts the backhaul link and the access link (slightly) by observing the impact on the CSI reported by the UE. For example, at time t0, the base station adjusts the backhaul link (e.g., the beam alignment therein) while keeping the access link in its current configuration, observing the CSI reported by the UE (improvement / degradation); at time t1, the base station adjusts the access link (e.g., the beam alignment therein) while keeping the backhaul link in its current configuration, observing the CSI reported by the UE (improvement / degradation); and so on. In this alternative, the links should be adjusted independently, and the adjustment frequency of one of the links may depend on the nature of the link, e.g., if the access link is more dynamic than the backhaul link because the UE is mobile and the NCR is static, the measurement frequency of the access link will be higher. Alternatively, if the UE is static (relative to the RIS) and the RIS is mobile (e.g., a vehicle-mounted RIS), the measurement frequency of the backhaul link will be higher.

[0264] In the third embodiment, the base station may configure the UE with a higher CSI frequency reporting configuration to ensure that the base station can ensure the quality of both links.

[0265] In a fourth embodiment, the base station may distribute the CSI reporting requirements on the backhaul link among multiple UEs so that the service quality of a single UE is not affected too much and the degradation is evenly distributed.

[0266] In the fifth embodiment, the base station may distribute the CSI reporting requirements on the backhaul link to the UEs in the non-connected state.

[0267] In a fourth embodiment, the RIS is equipped with a unit for eavesdropping on CSI probing signals sent on the uplink and downlink in the communication path between the gNB and the UE and determining appropriate reports to be sent to the gNB.

[0268] In the downlink case, the report may be a CSI index as previously described. In one possible implementation, the overheard CSI signal is analyzed by the RIS-CM 260 and the results are returned to the gNB. The process is the same as the standard CSI process except that the overheard CSI signal from the communication path is used. The gNB uses this direct measurement to adjust the backhaul downlink beam. In a variant approach, the RIS-CM also uses this information to adjust the backhaul uplink beam for the communication path.

[0269] In the uplink case, the RIS-CM analyzes the signal sent from the UE and determines the measurements to be fed back to the gNB. The gNB compares this with its own measurements obtained from the signal received via the backhaul. Any differences reflect the degradation due to the backhaul, and the gNB can use this information to update the uplink backhaul beam at the gNB. It can also advise the NCR-MT to make adjustments to the backhaul uplink beam used for the communication path. The signal processing that the RIS-CM has to do generally corresponds to the gNB procedures. Variant embodiments allow the RIS-CM to process the signal as a downlink signal and send appropriate measurements to the gNB.

[0270] Previous embodiments rely on the presence of at least one UE in order to provide measurements of the backhaul uplink. This leaves questions about how the system should behave when a relay is first discovered, since there is no way to establish a prepared backhaul beam for the first UE.

[0271] Therefore, in a fifth embodiment, the RIS uplink corresponding to the future communication path between the gNB and the UE is arranged to transmit some type of reference signal that the gNB can use to optimize the backhaul uplink beam setup. To avoid interference, this signal should only be used when no other signals are present. The base station can provide the RIS-CM with a schedule for signal generation.

[0272] In a first embodiment, optimized for simplicity, the transmitted signal is a noise-like signal using a noise source from the input stage of the repeater amplifier or thermal noise. The gNB can use measurements of the received signal strength of the noise signal to optimize the beam settings.

[0273] In a second embodiment, optimized for compatibility, the gNB may cause the RIS-CM 260 to generate or rebroadcast a standard reference signal on the uplink of the backhaul link in a specific direction. For example, the gNB may request the RIS-CM to rebroadcast the received signal on the backhaul uplink in four directions at times t0, t1, t2 and t3, while sending SSBs on the control downlink towards the RIS-CM at times t0, t1, t2 and t3. The RIS will then rebroadcast such SSBs (or any other reference signal, such as CSI-RS). Alternatively, if the RIS has the capability, the gNB may instruct it to generate the SSBs itself and send them in a specified direction at a specified time. The gNB may monitor the quality of the received reference signals (re)broadcasted by the RIS, identify the strongest one and use the extracted information to adjust its backhaul link, for example, to perform beam alignment or derive the CSI of the link.

[0274] In all alternatives, once the RIS-CM has received a control signal indicating that backhaul link configuration is required, the RIS may be activated (eg, a reference signal is sent).

[0275] In principle, this embodiment may also be used when the UE is served in a manner similar to the method disclosed in the first embodiment. The main difference is that in this fifth embodiment, the CSI signal is received over the backhaul instead of the control link.

[0276] In another embodiment related to the third embodiment, the base station (or master station) may broadcast a channel state information reference signal (CSI-RS) through different beams associated with the secondary station (or RIS or NCR) in a first step a. In other words, the base station may send the CSI-RS in a wide beam broadcast, and may command the secondary station to rebroadcast the CSI-RS through different directional beams in different directions. The UE returns the CSI for each sensed beam containing the CSI-RS, so that the master station may then have sufficient information to select the best beam to connect to the UE in the access link, which is represented as BBA. The master station may send the CSI-RS itself through N different beams in a second step b, and command the secondary station to rebroadcast the CSI-RS through BBA. The UE senses the N CSI-RSs and collects the CSI, and sends the CSI to the base station. The base station has sufficient information to configure the backhaul link, i.e., select the most suitable beam in the backhaul link. The process requires two steps to configure the access and backhaul links, where there is a single secondary station between the master station and the UE. In a multi-hop configuration where there are k secondary stations, k+1 steps are required, where each step involves beaming / measurement of N CSI-RSs.

[0277] In a related embodiment variant, the base station may broadcast the CSI-RS through one base station beam at a time, and for each of them, the secondary station is required to rebroadcast the CSI-RS through a different beam at the secondary station. If the primary station has N beams for allocating CSI-RS and the secondary station has M beams for allocating CSI-RS, a total of M*N CSI-RS measurements are required, and the UE must report M*N CSIs. This process also allows the base station (primary station) to determine the best beam for both the access link and the backhaul link.

[0278] In some cases, the auxiliary station may be a static device, but in other cases it may be a mobile repeater, i.e. a repeater mounted on a vehicle, a UAV or a repeater in a satellite. Such mobile devices may move following a known route and / or trajectory. In some cases, the location of the static access device may also be known to some extent. Therefore, in a further embodiment, the alignment of the backhaul link may follow a two-step approach, wherein the first step comprises a rough alignment based on a rough knowledge of the location of the auxiliary station, and the second step comprises a fine alignment based on any of the previous embodiments. The first step may determine a rough backhaul link alignment between the primary station (base station / gNB) and the auxiliary station (mobile repeater) based on the location of the primary station and the location of the auxiliary station. This may require configuration of the location / trajectory / path of the auxiliary station in the primary station, which may be done by AMF or OAM in this configuration.

[0279] In general, the above embodiments can be managed as a continuous iterative process, where in each step, the gNB and UE will align the antenna beams more closely and more towards the optimal position. In each step, the alignment of the backhaul link or the access link can be prioritized depending on the operating scenario.

[0280] The above embodiments may also be used independently or in combination with other solutions. For example, the fifth embodiment may be used as the first solution step for initial configuration of a backhaul link at a RIS, and later operations (eg, access link configuration) may be based on other technologies.

[0281] Interference Avoidance

[0282] In another embodiment, interference coordination / mitigation may be achieved by reusing RIS by multiple base stations (gNBs). In particular, to avoid interference caused by two access devices by operating one or more RIS elements at the same / similar frequency at the same time, the RIS may notify one or more access devices of the frequency and / or schedule used / requested / operated, for example, by using the RIS communication module 210 (e.g., by using a query / control communication protocol or by sending a notification / measurement). The RIS may be equipped with one or more sensors to detect interference. If interference is detected, this may be reported to one or more access devices, or the RIS may change its state or stop its operation. The RIS may use measurement information from one or more sensors and / or its built-in UE capabilities to identify the access device from which the signal originates and / or calculate the angle of arrival of the signal causing the interference, and report the information to one or more access devices. RF measurement information such as channel state information, signal strength, frequency information, and other information about the received signal, such as timing advance information, may also be reported to one or more access devices.

[0283] When a gNB uses RIS, its range may extend, causing potential interference in another area. The gNB may inform the second gNB that it wishes to use RIS including the desired coverage area, frequency and / or timing. This may be done, for example, via the Xn control plane interface between gNBs as defined by 3GPP. The second gNB may confirm / reject the use. The Xn interface may also be used to synchronize the clocks of the two gNBs and / or align their scheduling to use RIS.

[0284] A UE connected to a second gNB may measure a given interference level caused by the RIS currently controlled by the first gNB. The UE may inform the second gNB of the interference level and the origin. If the gNB sends a CSI-RS linked to the RIS with its identifier, the origin may be indicated. The second gNB may then inform the first gNB using the Xn control plane interface.

[0285] Another consideration relates to the fact that in the above-described embodiments, the gNB is able to communicate with a UE using the RIS at one time. However, existing gNBs are capable of MIMO operation by using multiple beams. In some scenarios, it is desirable to control the RIS to be able to handle multiple beams simultaneously. In an embodiment, this may be done when the RIS behaves differently depending on the properties of the incident electromagnetic (EM) wave (e.g., depending on frequency, polarization, etc.). For such a RIS, the gNB may control the RIS such that the reflection / refraction / redirection angle depends on the EM properties of the incident wave, such that the gNB may communicate with two different UEs simultaneously through the same RIS. The process may be as follows: 1) the gNB sets the RIS to a given state for a given period of time, the state involving refraction / reflection / redirection properties depending on certain properties of the incident EM wave (e.g., frequency, polarization, etc.); 2) the gNB sends two or more beams towards the RIS, each beam having a specific property (e.g., frequency, polarization, etc.) that is handled differently by the current RIS state, such that the beam is split at the RIS. In this process, the RIS state is such that the gNB will reach two or more UEs at different locations simultaneously when sending two or more beams towards the RIS, because the two or more beams sent from the gNB to the UE through the RIS will be reflected / refracted / redirected in different ways by the RIS. Similar behavior applies to smart repeaters.

[0286] In summary, systems and methods for determining and controlling a reconfigurable relay device (e.g., a reconfigurable smart surface, RIS, or smart repeater) have been described, wherein the reconfigurable relay device is registered and a wireless communication path is established from a network (e.g., an access device) to a terminal device via the reconfigurable relay device, and wherein optimal quality of both the backhaul link and the access link is maintained by independently forming an estimate of the link quality for each link. The network registers the reconfigurable relay device and determines the parameters required for its control. Control can be achieved through verified and accepted commands and queries. The relay state of the relay device can be set so that the beam used for the wireless communication path is correctly redirected at the terminal device.

[0287] Although the present invention has been described and illustrated in detail in the accompanying drawings and the foregoing description, such illustration and description should be considered illustrative or exemplary rather than restrictive. The present invention is not limited to the disclosed embodiments. It can be applied to various types of UE or terminal devices, such as mobile phones, vital signs monitoring / telemetry devices, smart watches, detectors, vehicles (for vehicle-to-vehicle (V2V) communication or more general vehicle-to-everything (V2X) communication), V2X devices, IoT hubs, Internet of Things (IoT) devices, including low-power medical sensors for health monitoring, medical (emergency) diagnostic and treatment equipment, for hospital use or first responder use, virtual reality (VR) headsets, etc.

[0288] A BS can be any network access device (such as a base station, Node B (eNB, eNodeB, gNB, gNodeB, ng-eNB, etc.), access point, etc.) that provides wireless access to devices in a geographic service area (indoors or outdoors).

[0289] RIS can be created by using smart devices (e.g., smart TVs or smart infrared panels) with hardware components that can be considered good reflectors (e.g., large glass screens or panels). RIS can also be embedded in objects such as billboards, building facades, posters, floor tiles, roofs, walls, etc. In addition, in the above embodiments, RIS can be replaced by smart repeaters or RF repeaters or any relay devices with controllable repeater or reflection functions.

[0290] In addition, at least some of the above-described embodiments may be implemented to provide a new product category of network equipment for 5G / 6G / xG cellular networks or (low / medium-cost) reconfigurable smart surfaces for improving coverage, reliability, and speed of cellular networks.

[0291] Those skilled in the art can understand and implement other variations of the disclosed embodiments by studying the drawings, the present disclosure and the appended claims when practicing the claimed invention. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit can implement the functions of several items recorded in the claims. The fact that certain measures are recorded only in mutually different dependent claims does not indicate that the combination of these measures cannot bring advantages. The foregoing description details certain embodiments of the present invention. However, it should be understood that regardless of the foregoing content appearing in the text, the present invention can be practiced in many ways and is therefore not limited to the disclosed embodiments. It should be noted that the use of specific terms in describing certain features or aspects of the present invention should not be considered to mean that the terms are redefined herein to be limited to include any specific characteristics of the features or aspects of the present invention associated with the term. In addition, those skilled in the art will understand that, in general, the terms used herein and particularly in the appended claims are generally intended to be "open" terms, e.g., the term "comprising" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "including" should be interpreted as "including but not limited to," etc. Those skilled in the art will further understand that if a specific number of an introduced claim recitation is intended, such intent will be explicitly recited in the claim, and in the absence of such a recitation, no such intent is present. For example, as an aid to understanding, the following appended claims may contain the use of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed as implying that the introduction of a claim recitation by the indefinite article "a" or "an" will limit any particular claim containing such introduced claim recitation to embodiments containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and an indefinite article such as "a" or "an", i.e., "a" and / or "an" should be construed as meaning "at least one" or "one or more"; the same applies to the definite article used to introduce a claim recitation. Furthermore, in those cases where a convention similar to "at least one of A, B, and C" is used, generally such construction is intended to be in the sense that a person skilled in the art would understand the convention, e.g., "a system having at least one of A, B, and C" would include, but is not limited to, systems having only A, B alone, C alone, A and B together, A and C together, B and C together, and / or A, B, and C together. Those skilled in the art will further appreciate that virtually any disjunctive word and / or phrase presenting two or more alternative terms, whether in the description, claims or drawings, should be understood to contemplate the possibility of including one of the terms, one of the terms, or both.For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B."

[0292] and Figure 2 and Fig.11 The described operations similar to the operations shown in can be implemented as program code units of a computer program and / or dedicated hardware of related network devices or functions, respectively. The computer program can be stored / distributed on a suitable medium, such as an optical storage medium or a solid-state medium, which is provided together with other hardware or as part of other hardware, but can also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems.

Claims

1. A method for operating a network, the network comprising a master station communicating with a terminal station via a secondary station, the secondary station being configured to relay signals exchanged between the master station and the terminal station, the secondary station exchanging data with the master station over a backhaul link and exchanging data with the terminal station over a dedicated access link, The method comprises managing the access link based on a measured quality or an indirect estimate of channel quality between the master station and the terminal station, and The quality of the backhaul link is managed based on indirect estimation or according to measured quality.

2. A method for operating a master station in a network, the master station communicating with one or more terminal stations via a secondary station, the secondary station being configured to relay signals exchanged between the master station and the one or more terminal stations, the secondary station exchanging data with the master station over a backhaul link and exchanging data with the terminal stations over a dedicated access link, The method comprises the master station managing the access based on the quality of measurements between the master station and the terminal station, and The primary station manages the quality of the backhaul link between the primary station and the secondary station based on indirect estimation or according to measured quality.

3. The method according to claim 1 or 2, wherein: A control link is also established between the primary station and the secondary station, and wherein the backhaul link quality is estimated based on the control link quality.

4. The method according to claim 3, wherein: The control link and the backhaul link are exchanged on overlapping bandwidth or on the same bandwidth.

5. The method according to claim 3, wherein: The control link and the backhaul link are exchanged on adjacent bandwidths.

6. The method according to claim 1 or 2, wherein: The backhaul link between the primary station and the secondary station uses the same frequency and / or antenna resources as a control link established between the primary station and the secondary station, And wherein the access link is managed based on channel state information exchanged between the primary station and the terminal station, and the backhaul link is managed based on channel state information for the control link exchanged between the primary station and the secondary station.

7. The method according to claim 1 or 2, wherein: The backhaul link indirect estimation is performed on active link estimation statistics.

8. The method according to claim 7, wherein: The active link estimation statistics include at least one of the following: - Maximum access link quality value, - the maximum access link quality value compared to a threshold, - the maximum access link quality value compared to the average of the access link quality values, - the average value of the access link quality value, - the average value of the access link quality values ​​compared to a threshold, - the variance of the sample or all access link quality values, - Variability of access link quality values ​​over time.

9. The method according to claims 7-8, wherein: If the number of end stations is greater than a predetermined threshold, the backhaul link indirect estimation is performed on active link estimation statistics.

10. The method according to claim 1 or 2, wherein: The primary station first adjusts the access link with the terminal station, determines how the link quality value evolves after the first adjustment, and decides whether to adjust the backhaul link based at least on the determination of the evolution of the link quality value.

11. The method according to claim 10, wherein: If it is determined that the link quality value remains substantially unchanged, the primary station adjusts the backhaul link.

12. The method according to claim 1 or 2, wherein: The primary station first adjusts one of the backhaul link with the secondary station or the access link with the terminal station, determines how the link quality value evolves after the first adjustment, and decides whether to adjust the other of the backhaul link or the access link based at least on the determination of the evolution of the link quality value.

13. A method according to any one of the preceding claims, wherein: The reporting frequency of the link access quality depends on whether the terminal station communicates with the primary station via a secondary station.

14. The method according to claim 13, wherein: If the end station communicates with the primary station via a secondary station, the reporting frequency of the link access quality is higher.

15. The method according to claim 1 or 2, wherein: The reporting frequency depends on whether the end station is communicating with the primary station via a secondary station and how many end stations are communicating with the primary station via the secondary station.

16. A method for operating a secondary station in a network, the network comprising a primary station communicating with one or more terminal stations via the secondary station, the secondary station being configured to relay signals exchanged between the primary station and the terminal stations, the secondary station exchanging data with the primary station over a backhaul link and exchanging data with the terminal stations over a dedicated access link, The method comprises a secondary station monitoring a probe signal from the primary station directed to an end station and / or from the end station to the primary station, A backhaul link quality report is generated to be sent to the primary station.

17. The method according to claim 16, wherein: The backhaul link quality report is sent on a control link between the secondary station and the primary station.

18. The method according to claim 16, wherein: The backhaul link quality report is sent to the primary station over the backhaul link.

19. The method according to claim 16, wherein: The sounding signal is one of the following: noise, thermal noise, a pseudo-random sequence, a reference signal, or a pilot signal.

20. A secondary station operating in a network, the network comprising a primary station communicating with a terminal station via the secondary station, the secondary station being configured to relay signals exchanged between the primary station and one or more terminal stations, the secondary station exchanging data with the primary station over a backhaul link and exchanging data with the terminal station over a dedicated access link, The secondary station comprises a controller for monitoring a channel state information signal from the primary station for the terminal station, the controller being arranged to control a transmitter to send a backhaul link quality report to be sent to the primary station.

21. A method for operating a secondary station in a network, the network comprising a primary station communicating with a terminal station via the secondary station, the secondary station being configured to relay signals exchanged between the primary station and the terminal station, the secondary station exchanging data with the primary station over a backhaul link and exchanging data with the terminal station over a dedicated access link, The method includes sending a probing signal to the primary station so that an estimation of the backhaul link quality is done at the primary station.

22. The method according to claim 21, wherein: The sounding signal is a reference signal inserted into the signal transmitted by the secondary station on the backhaul link.

23. The method according to claim 21, wherein: The secondary station receives a reference signal from the terminal station on the access link to estimate the quality of the access link, and the secondary station rebroadcasts the received reference signal on the backhaul link for the primary station to estimate the backhaul link quality.

24. The method according to any one of claims 21 to 23, wherein: The sending of the probe signal is performed during a period of low activity.

25. The method according to claim 24, wherein: A low activity period is a time window during which no signal is expected.

26. The method according to claim 24, wherein: A low activity period is a time window utilizing the master station arrangement during which no other probe signals are expected.

27. The method according to claims 21-26, wherein: The sounding signal is one of the following: noise, thermal noise, a pseudo-random sequence, a reference signal, or a pilot signal.

28. A secondary station operating in a network, the network comprising a primary station communicating with a terminal station via the secondary station, the secondary station being configured to relay signals exchanged between the primary station and the terminal station, the secondary station exchanging data with the primary station on a backhaul link and exchanging data with the terminal station on an access link, The secondary station comprises a transmitter for sending a probing signal to the primary station, so that the estimation of the backhaul link quality is done at the primary station.

29. A master station operating in a network, the master station communicating with a terminal station via a secondary station, the secondary station being configured to relay signals exchanged between the master station and the terminal station, the secondary station exchanging data with the master station on a backhaul link and exchanging data with the terminal station on an access link, The primary station is configured to receive a sounding signal from the secondary station and estimate a backhaul link quality based on a measurement of the sounding signal, The primary station is configured to adjust the backhaul link based on the backhaul link quality.

30. The master station according to claim 29, wherein: The primary station is further configured to adjust the access link based at least on backhaul quality.

31. A wireless network comprising a master station communicating with terminal stations via a secondary station, the secondary station being configured to relay signals between the master station and one or more terminal stations, the secondary station exchanging data with the master station on a backhaul link and exchanging data with the terminal stations on an access link, in, The network includes: an access link manager for managing an access link between the secondary station and the terminal station based on a measured quality or an indirect estimate of channel quality between the primary station and the terminal station; a backhaul link estimator for indirectly estimating the quality of the backhaul link between the primary station and a secondary station; and A backhaul link manager is configured to adjust the backhaul link based on the indirect backhaul link estimate or according to the measured quality.

32. A network according to claim 31, wherein: Adjustments to each access link independently include one or more of the following: adjusting the direction and shape of a radio beam between the secondary station and the terminal station, Select the modulation format and coding rate, Select the symbol rate, or Select an operating bandwidth.

33. The network of claim 31, wherein: Adjusting the backhaul link includes adjusting the direction and shape of a radio beam between the primary station and the secondary station.

34. The network of claim 31, wherein: The backhaul link between the primary station and the secondary station uses the same frequency and antenna resources as a control link established between the primary station and the secondary station, wherein the two links are managed according to channel state information for the control link exchanged between the primary station and the secondary station.

35. The network of claim 31, wherein: A plurality of access links are managed by the master station, and the quality of the backhaul link is estimated based on measured qualities of the plurality of access links.

36. A network according to claim 35, wherein: If the multiple access links, the backhaul link quality is estimated to be the same as the maximum value of the measured qualities.

37. A network according to claim 35 or 36, wherein: The primary station determines whether to adjust the backhaul according to one or more of the following: whether the quality estimate is below a predetermined threshold; an effect of a recent adjustment on said measured quality of said access link; Operation scenario.

38. The network of claim 31, wherein: A single access link is being managed by the master station, wherein the single measured quality is used to adjust both the backhaul link and the access link in separate steps, checking at each step to measure the impact on the measured link quality, possibly reversing the adjustment if the measured link quality degrades, wherein the master station makes a decision about which link to adjust based on the measured link quality and other parameters including one or more of: the impact of recent adjustments on the measured link quality; Operation scenario.

39. A network according to claim 37 or 38, wherein: The operation scenario includes at least one of the following: the auxiliary station is fixed relative to the main station, the auxiliary station is mobile relative to the main station, the auxiliary station is fixed relative to the terminal station, and the auxiliary station is mobile relative to the terminal station.

40. The network of claim 31, wherein: The secondary station comprises means for reading channel state information signals sent by the primary station and by connected terminal stations and sending reports to the primary station; at the primary station, using the reported information to derive a measure of the quality of each of a backhaul downlink and an access uplink.

41. A network according to claim 40, wherein: The secondary station sends the channel state information signal to the primary station.

42. The network of claim 40, wherein: The secondary station derives and returns a quality metric for each received link to the primary station based on the channel state information.

43. The network of claim 40, wherein: The secondary station additionally includes means for exchanging channel state information signals with the primary station across the backhaul link and deriving, at the primary station, a measure of the quality of the backhaul uplink using the received channel state information signals.

44. A network according to any one of the preceding claims 31 to 43, wherein: The uplink and downlink channels operate in the same radio frequency band; at the primary station, the quality of the downlink channel is estimated by using quality measurements of the associated uplink channel, and vice versa.

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