Smart Repeater Backhaul Link Control

Abstract

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

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 and reflective intelligent surfaces used in terrestrial-based networks, or satellites used in non-terrestrial-based networks. [Background technology]

[0002] RF repeaters have been a feature of cellular networks for several years, serving a useful purpose thanks to their ability to economically patch holes in cell coverage. Prior to Release 18, cellular repeaters compromised two back-to-back amplified repeater chains, each containing an input stage, some means of rejecting 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 are outside the direct coverage of the access device (e.g., base station or access point).

[0003] A particular advantage of this approach is that no changes to the protocol between the access device and the terminal device are required, meaning that the repeater is fully compatible with the cellular system.

[0004] Recent standards work has focused on improving repeater performance by allowing access devices to control aspects of their behavior. One problem with pre-Release 18 repeaters is that they are always "on," meaning that the amplifier is always operational. This is true even when there is no signal being repeated. In this case, the amplifier simply relays any noise and interference at its input to the output. This means that the area served by the repeater can be adversely affected by higher levels of background noise and interference. Conversely, noise picked up at the uplink input of the repeater is transmitted to the access device.

[0005] Therefore, current considerations exist for allowing the access device to control when to switch on the repeater amplifier and the level of amplifier gain to be used. In cellular and some wireless networks, the access device has overall responsibility for scheduling the use of the frequency range in which it operates, and therefore has the necessary knowledge on both the uplink and downlink to determine when to switch on the repeater amplifier. Operation can be improved by placing a local controller in the repeater connected to the access device via a control channel to operate the repeater at the request of the access device.

[0006] Such repeaters are called networked controlled repeaters (NCRs) to distinguish them from conventional uncontrolled repeaters. In this description, the term "smart repeater" is assumed to be the same as NCR.

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

[0008] For 5G, repeaters are expected to be particularly useful in the 5G FR2 frequency range, which covers the so-called millimeter wave frequencies (24,250 MHz to 52,600 MHz) (TS38.101-1). The shorter range of millimeter wave frequencies compared to the FR1 frequency range (410 to 7,125 MHz) means that uniform coverage of a given area is more difficult in the FR2 range, making repeaters a valuable tool in network planning. This is also true for other networks, which tend to use higher frequencies to improve bandwidth and latency. MIMO techniques such as beamforming are already being used at lower frequencies to improve coverage and reliability. Using millimeter wave frequencies greatly increases the range of MIMO, and future systems are expected to take full advantage of this technology. Therefore, to optimize the RF paths between the access device and the repeater, and between the repeater and the end device, it is expected that smart repeaters will have beamforming capabilities on both the so-called access side (between the repeater and the end 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, the information used to configure beamforming operation and other signaling aspects is obtained by exchanging channel sounding signals (sometimes collectively known as Channel State Information (CSI) signals) between the access device and the end device (where the originator uses feedback reported by the receiver to provide closed-loop control of the beam). In NCR, a similar process is used to manage the control link between the access device and the NCR-MT.

[0010] For terminal devices, the repeater introduces an additional link (backhaul), which is not explicitly taken into account by the CSI mechanism. Since there is no entity in the repeater capable of performing the lower layer UE functions required for CSI reporting across the backhaul, and there is no mechanism for uplink beam steering, the CSI information exchanged between the access device and the terminal device actually reports a set of combinations of backhaul and access link, which means that in the event of a poor channel quality report, which link needs to be adjusted?

[0011] Instead of using amplifiers for the repeater function, switchable metasurfaces are used.Recently, switchable metasurfaces have been developed, which offer many possibilities for improving the wireless communication path between access devices and terminal devices in wireless networks.

[0012] Various technologies can be used to implement such switchable metasurfaces. Generally, electronically switched metasurfaces are used, although physically movable reflective patches are also viable technologies. In general, there is no reason why these surfaces cannot be constructed using any relevant technology, as long as a general set of desired properties is implemented. Metasurfaces can even be used to form independent communication infrastructures using backscattered ambient radio signals.

[0013] Metasurfaces consist of periodic subwavelength metallic / dielectric antennas that resonantly couple with the electric or magnetic, or both, components of an incident electromagnetic field, exhibiting effective electric (represented by the permittivity, ε) and / or effective magnetic (represented by the permeability, μ) responses not found in nature.

[0014] Metasurfaces therefore represent a versatile concept for the manipulation of electromagnetic waves. Their ease of fabrication using planar circuit fabrication allows for great potential applications in the microwave frequency range. Huygens metasurfaces have attracted considerable attention because they feature near-total transmission and efficiently suppress reflection artifacts. At microwave frequencies, Huygens metasurfaces are typically fabricated with a printed circuit board (PCB) process, with three structured copper layers separated by a low-loss dielectric substrate.

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

[0016] Kun Woo Cho et al.'s paper "mmWall: A Reconfigurable Metamaterial Surface for mmWave Networks" proposes a reconfigurable metasurface ("mmWall") for millimeter wave networks. Unlike conventional wireless relay systems, this is an adjustable smart surface made of metamaterials that does not have transmitting or receiving antennas or amplifiers. When an incident beam strikes the metasurface, the metasurface naturally refracts the beam in the desired direction, regardless of whether the transmitter and receiver are in the same room ("mirror" mode) or different rooms ("lens" mode). The metasurface can also split the incoming signal into multiple beams and simultaneously steer multi-arm beams. The authors realize their design using a "Huygens metasurface."

[0017] However, other technologies exist for switchable mmWave manipulation surfaces besides metasurfaces.

[0018] Furthermore, a large intelligent surface (LIS) and a model for integrating base stations and LIS to determine the benefits of different ratios in a communication network are disclosed in "Stochastic Geometry Analysis of Large Intelligent Surface-Assisted Millimeter Wave Networks" by Yongxu Zhu et al., which concludes that the contribution of LIS is good when the number of base stations is limited, but not when there are a large number of base stations serving users.

[0019] Furthermore, Jun Zhao et al.'s "A Survey of Intelligent Reflecting Surfaces (IRSs): Towards 6G Wireless Communication Networks" calls these surfaces "Intelligent Reflecting Surfaces," and their behavior is limited to reflection, rather than both reflection and transmission.

[0020] With metasurfaces, there are still two parts to the link between the access device and the end device, and there is only one set of channel quality information that effectively covers both links in series. Therefore, 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 [Problem to be solved by the invention]

[0021] The present invention aims to improve the handling of poor link quality experienced by access and end devices when a link passes through a reconfigurable relay device (RRD), such as a smart repeater or externally controlled RIS, which lacks the inherent ability to perform its own wireless sensing (a "fully passive RIS"), or a partially active RIS that includes, for example, some wireless capability, signal processing capability, sensors, motors to orient individual sub-panels / sub-elements of the RIS, or active elements that not only change the angle / deflection of reflected electromagnetic waves but also amplify them. [Means for solving the problem]

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

[0023] In accordance with a first definition of the present invention, in a first aspect there is provided a method for operating a network comprising a primary station communicating with terminal stations via secondary stations, the secondary stations relaying signals exchanged between the primary station and the terminal stations, the secondary stations 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 the steps of managing an access link according to a measured quality or an indirect estimate of channel quality between a primary station and a terminal station; and managing the quality of the backhaul link based on the indirect estimation or according to the measured quality.

[0024] Similarly, in a second aspect of the present invention, there is provided a method for operating a primary station in a network, the primary station communicating with one or more terminal stations via secondary stations, the secondary stations relaying signals exchanged between the primary station and the one or more terminal stations, the secondary stations 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 the steps of: a primary station managing access according to a measured quality between the primary station and the terminal station; and the primary station managing the quality of the backhaul link between the primary station and the secondary station based on the indirect estimation or according to the measured quality.

[0025] According to a third aspect of the present invention, there is provided a method for operating a secondary station in a network comprising a primary station communicating with one or more terminal stations via the secondary station, the secondary station relaying 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 includes the steps of: monitoring, by a secondary station, a probe signal from a primary station for a terminal station and / or a probe signal from the terminal station to the primary station; generating a backhaul link quality report to send to the primary station.

[0026] Furthermore, according to a fourth aspect of the present definition of the invention, a secondary station is proposed operating in a network comprising a primary station communicating with terminal stations via the secondary station, the secondary station relaying 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 stations over a dedicated access link. The secondary station includes a controller for monitoring channel state information signals from the primary station for the terminal station, and the controller controls a transmitter to transmit a backhaul link quality report to the primary station.

[0027] Further, in accordance with a fifth aspect of the present definition of the invention, there is provided a method for operating a secondary station in a network comprising a primary station communicating with an end station via the secondary station, the secondary station relaying signals exchanged between the primary station and the end station, the secondary station exchanging data with the primary station over a backhaul link and exchanging data with the end station over a dedicated access link. The method includes transmitting a probe signal to a primary station such that an estimation of the quality of the backhaul link is made at the primary station.

[0028] According to a sixth aspect of the present invention definition, there is provided a secondary station operating in a network comprising a primary station communicating with a terminal station via the secondary station, the secondary station relaying 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 an access link. The secondary station comprises a transmitter for transmitting a probe signal to the primary station so that an estimation of the quality of the backhaul link is made at the primary station.

[0029] According to a seventh aspect of the present definition of the invention, there is provided a primary station operating in a network, the primary station communicating with terminal stations via secondary stations, the secondary stations relaying signals exchanged between the primary station and the terminal stations, the secondary stations exchanging data with the primary station over a backhaul link and exchanging data with the terminal stations over an access link. the primary station receives a probe signal from the secondary station and estimates a backhaul link quality based on measurements of the probe signal; The primary station adjusts the backhaul link based on the backhaul link quality.

[0030] 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 relaying signals between the primary station and one or more terminal stations, the secondary stations exchanging data with the primary station over a backhaul link and exchanging data with the terminal stations over an access link. This network is an access link manager for managing an access link between a secondary station and a terminal station according to a measured quality or an indirect estimation of the channel quality between the primary station and the terminal station; a backhaul link estimator for indirectly estimating the quality of a backhaul link between the primary station and the secondary station; and a backhaul link manager that adjusts the backhaul link based on the indirect backhaul link estimation or according to the measured quality.

[0031] According to a first aspect relating 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: a registration controller for discovering and / or registering reconfigurable relay devices in a wireless network; a path setter for determining and establishing a wireless communication path to at least one target terminal device via at least one registered reconfigurable relay device; and a state controller that controls a turning pattern of the at least one reconfigurable relay device according to the established wireless communication path, determines independent link quality estimates for 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 uses the link quality estimates to separately optimize the quality of the access link and the backhaul link.

[0032] According to a second aspect relating 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: discovering and / or registering a reconfigurable relay device in a wireless network; determining and establishing a wireless communication path to at least one target terminal device via at least one registered reconfigurable relay device; controlling a turning pattern of the at least one reconfigurable relay device according to the established wireless communication path; The method includes determining independent link quality estimates for a backhaul link between the access device and the reconfigurable relay device and an access link between the reconfigurable relay device and at least one terminal device, and separately optimizing the quality of the access link and the backhaul link using the link quality estimates.

[0033] According to a third aspect, a reconfigurable relay device (e.g., a RIS or a smart repeater) is provided. The reconfigurable relay device controls a redirection pattern 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. The reconfigurable relay device can be set to one of a plurality of configuration states in response to the relay state command. Each of the configuration states results in one of a plurality of redirection patterns for the received wireless signal. The plurality of redirection patterns includes at least one of reflection at a given reflection angle, focusing or defocusing, generation of multiple beams, refraction at a given refraction angle, and absorption. Each of the plurality of redirection patterns includes a backhaul link between an access device and the reconfigurable relay device and an access link between the reconfigurable relay device and at least one terminal device.

[0034] According to a fourth aspect, there is provided an access device comprising the apparatus of the first aspect.

[0035] 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.

[0036] Finally, according to a sixth aspect there is provided a computer program product comprising code means for generating the steps of the method of the second aspect when executed on a computing device.

[0037] The proposed route establishment via at least one reconfigurable relay device offers significant advantages for wireless communication systems, especially those using high frequencies such as 5G millimeter waves, since these systems have many blind spots as such frequencies are easily absorbed by many materials.

[0038] A scenario for the installation of a reconfigurable relay device (RRD) is that a building owner wants to improve the reception quality of (e.g., 5G-based) wireless communications within the building. The building occupants could be the owner's own staff, an industrial Internet of Things (IIoT) network, or possibly the general public (e.g., a public building). Presumably, the owner wants to improve reception for all wireless communications networks supplying individuals within the building. Therefore, it is desirable to use the RRD with all networks to improve communication with people within the building. Therefore, the device owner wants to be able to integrate with the operation of, for example, a 5G-based wireless communications network operator.

[0039] Another scenario for a reconfigurable relay device is a vehicle driver who wants to improve reception for his passengers. The vehicle in this scenario can be a private car or a multi-passenger vehicle such as a bus, coach, or train. In both cases, the goal is to provide network access to passengers regardless of the vehicle's configuration.

[0040] The prioritization of networks is determined, for example, by statistics of the networks serving the users in the building. Additionally, some networks may be given paid access to the RRD, possibly prioritizing their use of the RRD according to an auction or a fixed fee charged to rank first, second, etc. in the controller's priority list.

[0041] Systems with reconfigurable relay devices, such as RISs or smart repeaters, are likely to be significantly cheaper than additional base stations. The proposed reconfigurable relay devices are "passive" in the sense that they are controlled by an external controller, perhaps a core network device or an access device (e.g., a base station) that is responsible for searching for communication paths. It is possible to integrate some form of wireless sensing and internal control into these systems, whereby the reconfigurable relay devices are responsible for setting their state based on, for example, beam searching to target end devices.

[0042] Specifically, it has the following advantages: ● An installed reconfigurable relay device or system can be configured to be controlled by one or more networks to enable effective and secure operation in a communication system and to address edge cases such as the reconfigurable relay system going out of operation. • It can handle the operation of multiple networks simultaneously trying to use a single reconfigurable relay device when setting up communication paths. • It can provide a means for quickly computing a radio frequency (RF) communication signal path from an access device to an end device via a reconfigurable relay device. Additional independent communication paths can be established. For example, two UEs in the same direction from the access device can be served on the same frequency by beamforming directly towards one and via a reconfigurable relay device towards the other. Or, two access devices can be established with beams respectively towards two UEs, one using the path via the reconfigurable relay device (even if there is a direct line of sight (LoS) to that UE) to avoid interference when the LoS path affects the other UE but the path directed by the relay does not.

[0043] Thus, newly installed reconfigurable relay systems are registered so that the network or access device has the ability to command them to a desired state, including a discovery method if a formal registration process for reconfigurable relay devices is not available. This allows for the ongoing operation of discovery, configuration, and control of fully passive reconfigurable relay devices by the network or its access devices. Furthermore, it allows competition for control of purely passive reconfigurable relay devices between different networks and network operators. Even when a reconfigurable relay device is formally registered in a database (by itself or its owner), the access device still needs to discover or attempt to discover whether the reconfigurable relay device is reachable from the access device and can help establish a useful communication path to an end device.

[0044] Furthermore, given that an access device (e.g., a base station) potentially provides a large number of beamformed directions, only some of which interact with the reconfigurable relay device, that the reconfigurable relay device has a large number of states, most of which do not result in a communication path to the terminal device, or that the reconfigurable relay device has a large number of individual elements, such that checking each element is not feasible, and that any communication path to the terminal device includes both a backhaul and an access link, which are usually independent of each other, the proposed solution provides an optimal approach to finding a communication path to the UE via the reconfigurable relay device.

[0045] Additionally, queries and commands to the reconfigurable relay system are formatted and transmitted to support use in communications with end users where the command / query communications meet security and acceptability requirements (e.g., the network has appropriate priority and permission for use of the reconfigurable relay device as needed).

[0046] Furthermore, the proposed system is applicable to outdoor and indoor environments. A likely scenario is for example improving outdoor connectivity in urban scenarios where the reception quality is not as good as desired due to buildings, cars, etc. In this scenario, RISs installed in urban environments, such as on building facades or billboards, are used by network operators to improve network connectivity and services.

[0047] Furthermore, the proposed system is applicable to scenarios where the RRD is mobile and may move with a large number of terminal devices. The RRD provides a reliable link to the terminal devices via an access channel and connects the terminal devices to the network via a backhaul channel. In this scenario, poor reception quality is caused by the backhaul channel rather than the access channel.

[0048] According to a first option, which can be combined with any of the first to sixth aspects above, the reconfigurable relay device is looked up in a relay installation database (e.g., by a registration controller) and the required registration method is queried from the relay installation database or the reconfigurable relay device, or the reconfigurable relay device is discovered using an auto-discovery in locality method, in which local transmission paths with variable characteristics are noted, thereby allowing the path establishment to adapt to new network configurations in order to ensure optimal communication paths.

[0049] According to a second option, which can be combined with the first option or any of the above first to sixth aspects, the path establishment applies a transmission model in a local radio transmission model of the local environment to search for a suitable beam path, uses UE positions and relay states plus previous beam direction results stored in a database, or uses an artificial intelligence model to learn the relationship or association between beam settings and parameters (relay states and / or UE positions of neighboring reconfigurable relay devices as input parameters, and link quality and / or performance to the target terminal device as output parameters). Thus, a communication path including the associated reconfigurable relay system can be planned avoiding a full real-world search through beam directions and relay states of access devices.

[0050] According to a third option, which can be combined with the first or second option or any of the first to sixth aspects above, the steering pattern applied to at least one beam on the wireless communication path is controlled using a scheduling request, which allows adding scheduling considerations regarding future configuration states of the reconfigurable relay device to the control actions.

[0051] According to a 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 is applied in the path establishment to compensate for longer transmission path lengths via the reconfigurable relay device, thereby appropriately controlling the reception time at the target terminal device.

[0052] According to a fifth option, which can be combined with any of the first to fourth options or any of the first to sixth aspects above, the reconfigurable relay device is queried to determine its current configuration state, whereby the current turning pattern of the reconfigurable relay device is taken into account in the path planning and establishment process.

[0053] According to a 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 is a reconfigurable intelligent surface, another switchable metamaterial surface, or a smart repeater. Thus, the switchable metamaterial surface and / or the reconfigurable intelligent surface may be combined with a smart repeater or selected to achieve an optimized network environment.

[0054] According to a seventh option, which can be combined with any of the first to sixth options or any of the first to sixth aspects above, the reconfigurable relay device includes metadata including at least one of the following: functionality of the reconfigurable relay device and information necessary to obtain control thereof by the network, location and / or orientation information, a set of configuration states, a default configuration state, a reconfiguration rate, authentication, control and query methods, and a network control prioritization procedure. This option improves the efficiency of route planning and establishment by providing various initial information.

[0055] According to an eighth option, which can be combined with any of the first to seventh options or any of the first to sixth aspects described above, the reconfigurable relay device includes current information data including at least one of a current relay state indicating a currently set configuration state, a current controller priority parameter (e.g., a priority number) set to a current controller priority, a first flag indicating whether the current relay state is currently commanded, a timer value indicating a time period during which the current relay state has been commanded, and a second flag indicating an inoperable state. This option improves the efficiency of route planning and establishment by providing advanced information regarding the current state of the reconfigurable relay device. For example, determining whether a registered reconfigurable relay device has become non-functional can enable it to be removed from a possible communication path with an end user UE.

[0056] According to a 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 comprises at least one sensor for obtaining a position and / or orientation of the reconfigurable relay device, whereby the reconfigurable relay device can obtain direct information about its position and / or orientation and signal it to a database or (directly / indirectly) to a controlled access device for use in path planning.

[0057] According to a 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 includes a network usage log that stores information about the usage time of the relay device, the log information being used to obtain usage information for evaluating the efficiency and / or proper placement of the reconfigurable relay device.

[0058] According to an eleventh option, which can be combined with any of the first to tenth options or any of the first to sixth aspects, the reconfigurable relay device includes a priority list for storing the priority of the networks or devices controlling the reconfigurable relay device. The reconfigurable relay device compares the new priority of a new remote controller or new control network with the current priority of a current remote controller or current control network, and if the new priority is higher, the reconfigurable relay device stops control by the current remote controller or current network and allows control by the new remote controller or new network. This has the advantage of allowing priorities to be taken into account in route planning and scheduling based on the urgency or importance of the communication route. Furthermore, a network prioritization scheme can be used to prevent deadlocks in the control of the reconfigurable relay device by multiple competing users.

[0059] According to a twelfth option, which can be combined with any of the first through eleventh options or any of the first through sixth aspects above, the reconfigurable relay device includes a scheduler for scheduling configuration states requested from one or more networks or devices and determining whether the requested configuration states can be accepted. This allows multiple networks and / or access devices to use the reconfigurable relay device in parallel, reducing total transmission time by scheduling the same configuration states for the same period. Additionally, transmissions can be planned in advance (e.g., repeated transmissions), or, for example, if new data for transmission is expected soon, a time slot pre-scheduled for use of the RIS can be faster than attempting to negotiate the RIS at the next transmission.

[0060] According to a thirteenth option, which may be combined with any of the first to twelfth options or any of the first to sixth aspects above, the reconfigurable relay device includes an apparatus for observing the quality of signals passing through or traversing it. A quality report may be generated and provided to the access device.

[0061] It should be noted that the above apparatus can be realized based on a discrete hardware circuit having an arrangement of discrete hardware components, integrated chips, or chip modules, or based on a signal processing device or chip controlled by software routines or programs stored in memory, written to a computer-readable medium, or downloaded from a network such as the Internet.

[0062] It is to be understood that the methods of claims 1, 2, 16, 21, the secondary stations of claims 20, 28, the primary station of claim 29 and the wireless network of claim 31 have similar and / or identical preferred embodiments, in particular the embodiments as defined in the dependent claims.

[0063] It should also be understood that a preferred embodiment of the present invention can be any combination of the dependent claims or the above embodiments with the corresponding independent claims.

[0064] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. [Brief explanation of the drawings]

[0065] [Figure 1] FIG. 1 illustrates a schematic of the aggregate architecture of a RIS registration and control system according to various embodiments. [Figure 2] FIG. 2 illustrates a flow diagram of a RIS registration and control method according to various embodiments. [Figure 3]FIG. 3 illustrates a schematic of the RIS discovery and registration process according to one embodiment using a RIS installation database. [Figure 4] FIG. 4 illustrates a schematic of the RIS discovery and registration process according to one embodiment using an RI request for registration. [Figure 5] FIG. 5 illustrates a schematic of the RIS discovery and registration process according to one embodiment using automatic discovery. [Figure 6] FIG. 6 illustrates a schematic of the RIS query and command process according to one embodiment. [Figure 7] FIG. 7 illustrates a schematic of a network prioritization process according to one embodiment. [Figure 8] FIG. 8 illustrates a schematic of a communication path establishment process according to one embodiment using a full search. [Figure 9] FIG. 9 illustrates a schematic of a communication path establishment process according to one embodiment using a beam path memory. [Figure 10] FIG. 10 illustrates a schematic of a fault recognition process according to one embodiment. [Figure 11] FIG. 11 illustrates a flow diagram of a process for RIS-enabled communications in accordance with various embodiments. [Figure 12] FIG. 12 illustrates a first example of an improved beam steering process according to one embodiment. [Figure 13] FIG. 13 illustrates a second example of an improved beam steering process according to one embodiment. [Figure 14] FIG. 14 illustrates a schematic example of the management of the beam steering process and CSI estimation according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0066] Next, an embodiment of the present invention will be described based on a 5G cellular network environment.

[0067] Throughout this disclosure, the abbreviations "gNB" (5G terminology) or "BS" (base station) are intended to refer to an access device such as a cellular base station or a Wi-Fi access point. The gNB consists 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) and provides an interface to functions in the core network (CN). The RAN is part of a wireless communication network. It implements a radio access technology (RAT). Conceptually, it resides between communication devices such as mobile phones, computers, or any remotely controlled machine and provides connectivity to the CN. The CN is the core part of the communication network, providing multiple services to clients interconnected via the RAN. More specifically, it manages communication streams through the communication network and possibly other networks.

[0068] Furthermore, the terms "base station" (BS) and "network" are often used synonymously in this disclosure. This means, for example, that when a "network" is said to perform a particular operation, the operation may be performed by a CN function of a cellular network or by a particular base station that is part of such a cellular network, or vice versa. It can also mean that some of the functions are performed by a CN function of a cellular network and some of the functions are performed by a base station.

[0069] Furthermore, the term "verification" is intended to refer to processes or actions that include typical information technology (IT) security operations such as decryption, signature checking, authentication, authorization, and the like.

[0070] A Network Controlled Repeater (NCR) (the term "smart repeater" is used synonymously in this disclosure) includes at least a 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)) that operate under the local control of an NCR-MT (NCR Mobile Termination) that is 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., switched off or on, operating gain, etc.). Typically, the network controls the amplifiers so that signals transmitted from the network over the backhaul link are transparently relayed over the access link to the terminal device (and vice versa).

[0071] The NCR also includes an antenna system on the access link used to transmit and receive data to and from the terminal device, another antenna system on the backhaul link used to transmit and receive data to and from the network, and a third antenna system on the control link used to transmit and receive data between the NCR-MT and the network. The antenna systems on the backhaul link and the control link may be shared, but are generally independent systems operating in different frequency bands. All antenna systems have some degree of directionality and are intended to be under the control of the network. In this respect, the control link may behave similarly to that between the network and a directly connected UE. The access link may behave as an extension of the network's own directional antenna capabilities transported to the NCR's location. In either case, information for appropriately controlling the antenna radiation direction can be obtained from channel state information (CSI) signals exchanged between the network and the NCR-MT or between the network and each terminal device.

[0072] For the backhaul link, there is no equivalent to CSI signaling because NCR operates transparently to the signals on the backhaul and access paths. This means there is no way to directly measure the quality of the backhaul link, and no easy means to determine the most appropriate configuration. Because it operates in series with the access link, problems with the backhaul link can affect all end devices using NCR. In cases where the backhaul link and the control link can share resources, the backhaul link can default to the configuration used by the control link. If this is not possible, other methods must be used. This disclosure aims to describe such methods.

[0073] Various names have been given to (large area) surfaces that can passively redirect impinging radio waves, and whose reflective or transmissive properties can be changed, switched, and / or reconfigured to result in different passive behaviors depending on the set "state." These names include intelligent reflective surfaces (IRS), reconfigurable intelligent surfaces (RIS), large intelligent surfaces (LIS), reconfigurable metasurfaces (RM), programmable metasurfaces (PM), large intelligent metasurfaces (LIM), smart reflect arrays (SRA), software-defined metasurfaces (SDM), passive intelligent surfaces (PIS), and passive intelligent mirrors (PIM).

[0074] These surfaces can be switched between different states. Each state reflects or transmits radio waves differently. The difference between these types of surfaces is that some have the inherent ability to determine signal strength. For example, they contain reflector / transmitter capabilities as well as receivers, and can therefore function as independent "relay-like" systems, e.g., capable of performing their own beam path finding (although the reflected / transmitted signal comes from elsewhere). Their resemblance to relays allows them to be integrated into communication standards (e.g., cellular standards).

[0075] Such switchable metamaterial surfaces offer many possibilities for improving communication paths between base stations or other types of access devices and terminal devices (e.g., UEs).

[0076] In the following, the term "reconfigurable intelligent surface" or "RIS" will be used to refer to any of the above surface types. In the embodiments, it is assumed that the array of RISs is fully passive, i.e., they have no inherent wireless sensing capabilities and therefore cannot perform beam-finding or the like, but can be defined by switching states when commanded by an external controller, and it is the responsibility of the external controller to determine the appropriate state to set the RIS in. The RIS may also be partially passive and / or partially active (e.g., including some wireless functionality, signal processing functionality, sensors, motors to orient individual sub-panels / sub-elements of the RIS). Note that in this disclosure, only blocks, components, and / or devices related to the proposed data distribution functionality are shown in the accompanying drawings. Other blocks have been omitted for the sake of brevity. Furthermore, blocks designated with the same reference numerals are intended to have the same or at least similar functionality, and therefore their functionality will not be described below.

[0077] In many cases, a RIS can be used where a smart repeater / NCR is used, and vice versa. For both RIS and smart repeater / NCR, the problem of controlling the backhaul link is similar. In the following, the terms "RIS" and "smart repeater / NCR" can be used interchangeably (unless specifically indicated to apply only to a smart repeater / NCR or a RIS). The term "reconfigurable relay device (RRD)" is used to represent a RIS and / or a smart repeater / NCR, or other devices that enable the same functionality.

[0078] The following embodiments enable enhanced link quality management for wireless communications involving an access device (eg, a base station (BS)), an RRD, and a terminal device (eg, a UE).

[0079] More specifically, RRDs are seamlessly integrated into 5G networks through the maintenance by the BS (e.g., gNB in ​​5G terminology) of a 3D transmission database of the local area, including buildings, objects, neighboring BSs, and all known RISs and their characteristics (including the behavior of RRDs and the means to control them). The resulting 3D radio propagation model is used, along with some limited local search, for the selection of communication channels, including both BS beam directions and the state of RRDs controlled by the network and / or BS.

[0080] In use, the BS performs an analysis of the requested communication, which depends on the estimated location of the user (UE) and predictions from its 3D radio propagation model (e.g., based on the 3D transmission database mentioned above). The BS uses its beamforming capabilities and can actively switch / control the behavior of the RRDs under its control to maximize communication quality and / or throughput (preferably while minimizing transmission power levels).

[0081] In the following description, a RIS is used as a representative example of an RRD. It should be understood that a smart repeater / NCR can be used in place of a RIS (unless specifically stated to apply only to a smart repeater / NCR or a RIS). Therefore, this description also covers operation with a smart repeater / NCR.

[0082] RIS control interface and architecture The following embodiments cover the registration process, the RIS query and command process, the communication path establishment method from the BS to the UE via the RIS, the network control prioritization process for the command originator (i.e., the controller), and the RIS failure recognition process.

[0083] FIG. 1 illustrates a schematic of the architecture of a RIS registration and control system (with optional elements and features) according to various embodiments.

[0084] The proposed system for RIS-enabled communication includes a base station (BS) 10, at least one reconfigurable relay device (e.g., a reconfigurable intelligent surface (RIS)) 20, and a user terminal device (UE) 40.

[0085] The RIS control base station 10 includes an RF communication function (RF-COM) 150 conforming to the relevant communication standard (e.g., 5G NR) and a network-to-RIS communication system (NW-RIS-COM) 110, also known as a state controller, for sending and receiving communications to and from the RIS 20. Such communications may simply be communications to the RIS 20 using its standard communication function based on, for example, an F1-C interface, or may include messages sent to a designated internet address. The network-to-RIS communication system (NW-RIS-COM) 110 includes a BS-to-RIS transmit and receive system (NW-RIS-TRX) 1110, a RIS query and command function (RIS-C / Q) 1120, and a command / query format (C / QF) 1130 for verification procedures.

[0086] The UE 40 includes an RF communication function (RF-COM) 410 to enable communication with the BS 10 that conforms to a relevant communication standard (e.g., 5G NR).

[0087] Additionally, the BS 10 includes an optional RIS database (RIS-DB) 120 that contains a list of local RISs and their metadata, and optionally the BS beam directions targeting each RIS. Only beam directions targeting each specific RIS may be stored. Optionally, the metadata provided by the RIS 20 may be extended to include aspects of its performance as determined by the network or BS 10, such as its optimal beam direction, availability, usefulness for communication, and variations in performance due to weather or time of year.

[0088] The RIS database 120 is divided into RIS information that is general to a network that controls many local BSs (e.g., the location of the RIS and its capabilities) and information that is specific to an individual BS (e.g., whether a particular UE can be reached via the RIS that the BS controls). For example, access to a particular RIS is negotiated on behalf of the network operator by one of its BSs, and certain information is general to all BSs for that RIS. However, the ability to use a particular RIS may differ between individual BSs; for example, a RIS may be obscured in one BS but not in another.

[0089] Additionally, the BS 10 includes a communications path (CP / RIS-PM) 130 that includes a RIS planning module, which includes: ● An optional Local Radio Transmission Model (LRTM) 1310 of the local environment, including the presence, location, and behavior of any RIS that can be used to identify the correct configuration of BS beam directions, and the selection of RIS and RIS states for communicating with the UE at the defined location. Optionally, the performance of the RIS in the Local Radio Transmission Model 1310 is determined based on additional calculated RIS database components, such as performance due to weather and time of year. An optional database (L / RIS-S-DB) 1320 that stores UE locations, RIS metadata (e.g., RIS capabilities, RIS locations, and / or RIS states) and links a particular RIS, the state settings of that RIS, and the locations of UEs with which the BS10 has successfully communicated using that RIS and RIS state, given one or more UE locations, RIS identities and locations (or beam directions to that RIS), and / or RIS states associated with past communications via the RIS to that UE location. • An optional RIS beam searching function (RIS-BS) 1330, which allows for local or global searching of the RIS state for optimal communication with the UE (thereby deriving or obtaining the local state from the RIS state topology map contained in the RIS metadata).

[0090] Additionally, the BS 10 includes a RIS registration function (RIS-REG) 140, also known as a registration controller, which includes at least one of the following: • Optional RIS Installation Database Query (RIS-I-DB-Q) function 1410. This provides the ability to query the RIS Installation Database (RIS-I-DB) 30 and determine new entries in the RIS Installation Database 30 available to the RIS control network or BS 10, and return the necessary means to negotiate access to the RIS. • An optional RIS Registration Request Response (RIS-REG-REQ-RES) function 1420, which provides the ability to configure registration entries in response to communications from the RIS as part of the RIS registration process, which may be hosted on a network such as the Internet or on a particular operator network if the RIS is associated with a particular operator. RIS Registration Process Function (RIS-REG-P) 1340, which provides the ability to negotiate access to the RIS, including at least one of negotiating validation measures, obtaining control and query access, agreeing on prices and pricing methods (if any), and obtaining access to and / or entering RIS metadata 220 into the RIS database 120. ● An optional beam direction and / or UE location log (BD / UE LOG) 1440, which associates beam directions with all UE locations (obtained while communicating with the UE 10) that have communicated over a period of time. This log 1440 can be analyzed using beam direction and / or UE location log analysis to identify beam directions where there is a large variation in UE location, consistent with the presence of a RIS in that beam direction. As one example, the UE location is estimated by the BS 10 for each UE while it is communicating. In another example, the self-reported UE location can be refined by additional estimates made by the BS.

[0091] Additionally, the RIS 20 includes at least one of the following components or functions: i. Reconfigurable Surface (REC-SF) 270. This is a multi-element electronically controllable surface that can be set into several configuration "states," each state resulting in a different redirection pattern of radio waves at frequencies associated with the communication. Such redirection includes at least one of the following: ● Reflection at a given angle of reflection, ●Transmission, ●Focusing or defocusing, ●Generation of multiple beams, Refraction at a given refraction angle (this option is important to allow communication inside buildings, etc.), ● Absorption (This option can be used to reduce noise or isolate a given environment).

[0092] The configuration states are represented by a discrete number of state identifiers (e.g., State 1, State 2, State 3) or a set of signal characteristics (e.g., (desired) reflection angle, focus, number of beams, absorption / attenuation coefficients, etc.) as a representation of the turning pattern.

[0093] A configuration state may also be the individual state of each element in a multi-element RIS, represented as a bitmap (e.g., identifying the on / off state of each element) or a multidimensional array (e.g., identifying the phase shift, absorption, focus information, angle information, etc. of each element). Elements in a RIS may be electronically controllable (to change their individual state and / or desired properties) or physically controllable (e.g., by motors to physically control the angle of the RIS). For control of optical communications, a RIS may have elements that are lenses, whose focus, opacity, curvature, polarization / filter state, and angle of reflection can be (individually) controlled.

[0094] These configuration states can be controlled by an access device (e.g., a base station) of the wireless network by indicating a desired state, which causes the RIS to reconfigure elements of the RIS in a manner that achieves the desired state, or by sending control information from the access device to the RIS with detailed (re)configuration parameters (e.g., for each element of a multi-element RIS individually) to reconfigure the RIS to the desired state. ii. A RIS control module (RIS-CM) 260 that sets 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 saves the current state of the reconfigurable surface 270, which is currently set as the RIS state. Additionally, the RIS control module 260 includes an optional state cycling (ST-CYC) capability or function 2610 that performs state cycling upon initial startup. The optional state cycling (ST-CYC) capability or function 2610 periodically switches its state to a randomly significantly different state. This behavior can be stopped when the RIS 20 is successfully registered with one or more networks and / or is controlled by an access device, or the function can be continuous when the RIS 20 is not commanded to prevent the RIS 20 from being used as a passive surface by a BS. This is intended to prevent others (e.g., a BS of a network operator that does not have a usage agreement with the RIS owner) from using it as a passive surface. Another option is for the RIS 20 to continuously change state and configure the state according to the network's needs only when the network decides to do so. Alternatively, the network (e.g., BS 10) controlling the RIS 20 may know the schedule of RIS states. For example, the RIS 20 may provide the BS 10 with a schedule of the times it rents the RIS 20, which it uses to select appropriate communication time slots for using the RIS when in a particular state. iii. RIS Metadata (RIS-MD) 220. This contains information about the RIS (e.g., to derive the RIS's functionality and control by the network). This includes at least one of the following: ● Identity information (for example, this information is entered by the installer). • Position and orientation (for example, this information is entered by the installer of the RIS 20 or the RIS sensor (RIS-S) 250, which determines the position and 3D orientation and communicates it automatically, for example, during the registration process). ● A set of configuration states (e.g., a set of discrete or possibly continuous state values ​​(including direction, focusing, etc.) expressed as the way incident radio waves entering a surface at a particular angle are transformed into outgoing radio waves. The states are organized into a topology map (RIS state topology map) that shows which states are "adjacent", i.e., giving results such as the most similar beam directions, allowing a local search for the optimal communication path starting from the starting RIS state). Default RIS state (e.g., the surface's default state (the state that the RIS 20 sets itself to in the absence of a commanded state. The RIS 20 will likely default to a particular state when it is not powered on or commanded to adopt other states (which may not be the same). The network needs to know this default state, as it will likely be in this state before commanding the network to be in some state optimized for communication (unless the RIS 20 is configured to do "state cycling" and not be used as a passive surface, where it has random, changing states)). ● The switching speed of the reconfigurable surface (the RIS is able to switch its state as quickly as possible, since slow switching would hinder the BS's ability to use the RIS to quickly set up high-bandwidth, reliable communications with UEs, especially mobile UEs, and to cycle through the states of the RIS to reliably search for a communication path. The state switching speed of the RIS 20 indicates the number of states that can be searched in a reasonable amount of time when required to search for a communication path, or separately indicates the speed or time duration at which it is commanded from one state to another during operation). ●Authentication, control, and query methods (e.g., a control method where a signal sent to the surface sets the surface to a specified state (either a set of category values ​​or a small set of consecutive values); and / or an authentication method whereby it can determine that control signals sent to the RIS 20 were sent by a valid originator. The authentication method also ensures freshness of commands. Some form of command validation can be established during the registration process; for example, security keys should be exchanged so that the RIS 20 can determine that any commands sent to it in the future actually originate from an authenticated source with permission to command it). ● Network control prioritization procedures (e.g., priority assigned to control of RIS depending on network operator or BS identity) Costs (e.g., if there are costs associated with controlling the RIS20 (which the owner of the RIS20 charges to the network that controls it)), can be derived by the network, e.g., in terms of both quantity and schedule (e.g., pay-per-use, flat-rate, time-based pricing, etc.). ● The device type (e.g., a reflective RIS (allowing the signal to be reflected to UEs on the same side of the base station (BS)), a transparent RIS (allowing the signal to pass through the RIS to serve UEs on the other side of the BS), or a hybrid RIS (the RIS has dual reflective and transparent functionality) (this also includes information about, e.g., the number of individual sub-elements / panels, the materials used, and the physical dimensions / size of the device). ● Functionality (e.g., radio / communication capabilities, relay capabilities (e.g., support / compatibility of IAB relays, smart repeaters, ProSe relays), number / type of sensors, characteristics and (relative) position of RIS elements, maximum / minimum reflection angles, supported and / or non-supported frequencies or frequency ranges, supported reflection angles, (number of) motors that physically control the angle of the RIS and RIS elements, and the degrees of freedom they allow).

[0095] Additionally, the RIS 20 includes a RIS communication module (RIS-COM) 210 that receives commands and queries and returns results. The RIS communication module 210 includes at least one of the following: RIS Transmit and Receive System (RIS-TRX) 2110. This uses the same wireless communication system as the RIS control network (e.g., BS 10), e.g., 5G NR, but includes sending and receiving messages via other locally connected wireless communication systems or the Internet using WiFi, Ethernet, Bluetooth, etc. To seamlessly use these RIS within the communication process with the UE 40, state switch commands communicated to the RIS 20 are sent or routed through the same communication network over which the BS is attempting to establish a communication path to the UE 40. However, other means of communication with the RIS 20 (e.g., via Internet Protocol, fixed Internet link, WiFi, Bluetooth, etc.) can also be used, but may introduce delays in the process of establishing communication with the UE 40. • A RIS registration function (RIS-REG) 2130 that sets up the registration of the RIS 20 in the RIS installation database 30 . RIS Command / Query Validation and Acceptance (RIS-CQ-V) function 2120, which includes a validated network list (e.g., a list of networks or BSs validated for control of that RIS 20), an optional RIS network priority list (e.g., giving a negotiated priority number for each validated network), optional additional information needed to accept commands / queries from networks (such as a "network blacklist"), and an optional function to initiate registration with one or more networks (e.g., a RIS registration request function).

[0096] Additionally, RIS 20 includes RIS current information data (RIS-CID) 230, which includes a current RIS state indicating the configuration state currently set for reconfigurable surface 270, an optional current controller priority number set to the current controller priority number (if not commanded, this flag is set to zero (NULL)), an optional currently commanded flag indicating whether the current state of RIS 20 / reconfigurable surface 270 is currently being commanded (e.g., by another network / BS), an optional time in duration timer (e.g., a timer and timer value indicating how long the current state has been commanded by the network), and an inoperable flag (set to "false" if RIS 20 is properly powered and can set its state as commanded, and set to "true" if RIS 20 is not currently able to set its state as commanded).

[0097] Optionally, the RIS 20 includes a network usage log (NU-LOG) 240, which stores the total time each network / BS used the RIS 20 / reconfigurable intelligent surface 270 during the last period, and optionally stores a complete list of the times and lengths of RIS 20 usage for each network during a given period.

[0098] As a further option, RIS 20 includes RIS sensors (RIS-S) 250, e.g., a set of sensors that collect the position and orientation of reconfigurable surface 270. By way of example, RIS 20 includes a GPS / GNSS module for determining its position and / or receiving clock synchronization information, e.g., a gyroscope and / or compass for determining its orientation.

[0099] Optionally, the system includes a public RIS installation database (RIS-I-DB) 30, which stores details of all RIS installations and registration request procedures for them. These functions include: i. Means / functions for entering new RIS installations into the RIS installation database 30; and ii. Means / functionality for querying the RIS installation database 30 according to location, RIS type, and / or RIS characteristics.

[0100] Smart Repeater In general, RF signal repeaters share many of the same characteristics as reflective intelligent surfaces, but rather than using signal reflections to propagate the RF signal, they rebroadcast the RF signal using RF transmitter and RF receiver front ends. However, one advantage of RIS is that the gNB can dynamically control the state of the RIS. In another embodiment, a smart repeater interface can be based on the proposed system and method.

[0101] An RF repeater is a device that "repeats" signals received from an access device (e.g., 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 includes not only the RF layer of the access device (e.g., gNB) but also the PHY layer of the control plane, e.g., a communication module or UE similar to the RIS communication module 210 or RIS-UE 50 for transmitting and receiving information to and from the access device. The access device (e.g., gNB) can then steer the smart repeater with parameters such as timing configuration (UL / DL), beamforming, or on / off.

[0102] The steering functions of the smart repeater and the RIS are expected to be similar. As mentioned above, the access device (e.g., gNB) can command the RIS to set a given reflection pattern for a given period of time. This is similar to configuring beamforming in a smart repeater. The access device (e.g., gNB) can control the RIS for some time slots, which is similar to providing a given timing configuration to the smart repeater. Furthermore, the RIS is turned off by default and therefore only operates when the access device (e.g., gNB) is using the RIS.

[0103] From this perspective, the embodiments of the present disclosure can also be implemented as a smart repeater or a combination of a RIS and a smart repeater. For this reason, the RIS 20 in the embodiments of the present disclosure can also be a smart repeater. Therefore, in the embodiments of the present disclosure, the term RIS 20 can be replaced with the smart repeater 20. In a device architecture, the reconfigurable surface (REC-SF) 270 can be replaced with a transceiver including an RF receiver front-end and an RF transmit front-end coupled to one or more antennas, whereby the controllable states include states / settings controlling on / off states, beam steering (e.g., number of beams, beam direction), transmit power, frequency, and / or timing of the transmitted RF signal (e.g., configurable delay), whereby the steering pattern can include generating multiple beams, focusing or defocusing a beam, directing a beam at a specific angle (wherein the angle is relative to a reference line or magnetic north, or the angle between the incoming and outgoing beams (i.e., similar to a deflection / refraction angle)), amplifying the incoming signal (e.g., by providing amplification gain on command), delaying the signal (e.g., by providing a delay time or specific timing of the outgoing signal on command). The transceiver can be the same as the RIS transmit and receive system (RIS-TRX) 2110, reuse / share components within the RIS-TRX 2110, or be a separate subsystem.

[0104] RIS registration and control procedures FIG. 2 illustrates a flow diagram of a RIS registration and control method according to various embodiments.

[0105] In the Network Registration (NWR) step S201, the network (e.g., BS 10) registers the RIS 20 and determines all parameters necessary for its control. Control is exercised by verified and accepted commands and queries.

[0106] In a subsequent route determination (PD) step S202, the network / BS determines the optimal communication route with the UE (e.g., UE 40). This involves directing the path of the beamformed (directional) signal to the RIS 20 and configuring the RIS state so that the beam is properly steered to the UE. The network / BS is triggered to communicate with the UE via the RIS, initiate a route determination step, and / or configure / command the RIS if the LOS signal between the access device and the UE or between the RIS and the UE is degraded or dropped (e.g., due to an obstruction) or if there is a peak in signal strength (e.g., due to the signal being reflected through the RIS). This is discovered through measurement reports or CSI feedback from the UE and / or the RIS (e.g., measurement reports or CSI feedback regarding the link between the RIS and the UE). In a particular example, if measurement reports (e.g., through its RSRP feedback or UE RX-TX feedback) indicate that the UE is moving in a particular direction but adjusting the beam toward the UE does not improve or actually degrades signal quality / strength, this indicates that the UE is obscured by an obstruction. This causes the network / BS to trigger a local beam search or other communication / beam path establishment process (described in further embodiments) to determine the RIS and / or the status of the RIS and establish a communication path to the UE via the RIS.

[0107] In the next state determination (SD) step S203, the network / BS queries the RIS 20 to determine its state, which includes determining whether it is being commanded by another network and optionally the current commanded priority level.

[0108] Next, in Beam Steering and State Command (BD / SC) step S204, if the path found in step S202 is one that achieves good quality communication and the network / BS is able to command / control the RIS 20, the network / BS will steer its beamformed (directional) signal to the RIS 20 and command the associated state of the RIS 20. This procedure is repeated as the UE moves, or as large objects in the environment that obstruct the RF communication path move.

[0109] Finally, in a check (CHK) step S205, the network / BS periodically checks whether the RIS in the RIS database 120 remains operational.

[0110] Therefore, newly installed RIS systems are registered so that the network / BS can command the RIS to a desired state, including discovery methods if the formal RIS registration process is unavailable. This allows communication paths involving related RIS systems to be quickly planned without performing a full real-world search of BS beam directions and RIS states. Furthermore, registered RISs that are no longer functioning can be removed from possible communication paths with end users.

[0111] FIG. 5 illustrates a schematic of a RIS discovery and registration process according to one embodiment using automatic discovery of the RIS 20 in a locality manner.

[0112] When the RIS 20 is installed and powered on, but not yet registered with any network, the initial behavior of the RIS control module (RIS-CM) 260 is to configure the state cycling (ST-CYC) function 2610, which causes the RIS 20 to periodically change its state to a randomly selected state between isolated states.

[0113] Additionally, the owner of the RIS 20 configures the RIS 20 to activate this state cycling function 2610 when not controlled by a network / BS (rather than the default RIS state), to prevent any network from using the RIS 20 as a passive surface without (for example) proper payment or authorization, which would otherwise allow it to be used as a passive surface when the state is predictable.

[0114] When the RIS 20 is registered and controlled by at least one network, the RIS 20 can adopt a state commanded by the registered network. The RIS 20 may also operate a state cycling function 2610, which causes it to randomly change states when not actively commanded to a state. In either case, beams directed at the RIS 20 from unregistered BSs will be steered in different directions at different times.

[0115] A network (i.e., BS 10) to which the RIS 20 is not currently registered or actively commanding may use the beam direction / UE location log (LOG) 1442 analyzed in beam direction / UE location log analysis (BD / UE) 1440 to note / determine that the beam path to a particular end UE location may vary significantly when the BS beam is pointed in a particular direction. That is, a particular beam direction is associated with a log of end user / UE locations that vary significantly at different times. Alternatively, the network (i.e., BS 10) may note that a BS beam pointed in a particular direction provides a particular stationary UE with variable (e.g., intermittent and periodic) connectivity. This analysis may indicate that the RIS 20 is present in that beam direction. The corresponding information stored in the beam direction / UE position log 1442 is obtained from the RF communication function (RF-COM) 150 based on the beams directed to the reconfigurable surface (REC-SF) 270 of the RIS 20 (e.g., based on collection of measurement reports from the UE or RIS registered with the BS 10, including RSRP values ​​per beam / SSB index). Based on this information / analysis, the network (i.e., the BS 10) decides which RIS to select, whether to register / connect to the RIS 20, and whether to send commands / queries to the RIS 20.

[0116] With the newly identified location and / or beam direction of the RIS 20 in mind, the network may seek a means to establish registration with the RIS 20 in a variety of ways, such as by searching in a database, sending a direct request using a wireless communication protocol (e.g., a discovery protocol), or sending a communication to a business or individual within that premises. In the example of FIG. 5, the RIS registration function (RIS-REG) 140 of the BS 10 retrieves (510) a unique identifier for the RIS 20 (and optionally a method for requesting registration) from the RIS installation database (RIS-I-DB) 30, for example, based on the results of the beam direction / UE location log analysis 1440.

[0117] Once the RIS registration method is obtained, the RIS metadata 220 of the RIS 20 is provided to the BS 10 using a negotiation and verification procedure 520 between the RIS registration process function (RIS-REG-P) 1430 of the BS 10 and the RIS registration function (RIS-REG) 2130 of the RIS 20. The RIS metadata 220 is then entered into the RIS database 120 of the BS 10. If the RIS 20 includes RIS sensors (RIS-S) 310, the position and / or orientation of the RIS 20 is collected from these sensors 310 and communicated as part of the RIS metadata 220.

[0118] The BS 10 uses the RIS registration process function 1430 to negotiate the ability to control the RIS 20 to obtain validation, priority for RIS usage, and optionally, a payment price and / or schedule for use of the RIS 20. If this negotiation is successful, the command / query validation process is agreed upon as before. This is the validation process for subsequent commands or queries.

[0119] Active discovery of communication paths via RIS Given the large search space introduced in the beam search by one or more RISs with the option to communicate with a UE, conventional beam search techniques, extended by commanding cycling through the RIS states, can result in significant delays. Therefore, we propose an improvement to beam path determination (e.g., BS beam direction and RIS state) for communicating with a UE at a specific location. As mentioned above, the BS is triggered to initiate path determination, for example, when the LOS signal between the access device and the UE or the signal between the RIS and the UE is degraded or dropped (e.g., due to an obstruction), or when there is a peak in signal strength (e.g., due to the signal being reflected through the RIS). This is discovered through measurement reports or CSI feedback from the UE or RIS. Additionally or alternatively, the network / BS may be triggered to initiate the path determination step when it receives a message from / via the RIS that the UE has lost connectivity and / or wishes to communicate through the RIS, for example, after receiving a discovery message via a sidelink from the UE (as described in further embodiments).

[0120] The base station performs a real-world active search for the optimal communication path to the UE, possibly cycling through RIS states (or elements used one at a time) and beam directions until it determines a RIS state that achieves sufficiently good communication for its operational requirements. If the RIS has many possible states (or elements), this type of search may not be fast enough to routinely establish communication. Therefore, the use of this real-world search is limited to the first few times the network uses the RIS, after which one of the other proposed processes is used.

[0121] FIG. 8 illustrates a schematic of a communication path establishment process according to one embodiment using a real-world exhaustive search.

[0122] The proposed beam path establishment process allows the network to determine the location of the UE 40, determine whether the RIS encompassing it is suitable for communication with that UE 40, determine the optimal state in which the RIS is configured to support that communication, and determine the correct beamforming direction to either directly to the UE 40, a passive surface that redirects it to the UE 40, or a RIS that is configured in the correct state to transmit / reflect the beam back to the UE 40.

[0123] In the embodiment of FIG. 8, a beam search is proposed that supports transmission ray tracing modeling.

[0124] The network (e.g., BS 10) maintains a 3D local radio transmission model (LRTM) 1310 of the environment, including the effects of known RISs and their conditions, 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 condition selection to achieve the best communication with a UE at a particular location.

[0125] Once a suitable communication path has been found by the model, for example, a small-scale real-world local search can be performed by the RIS Beam Search Function (RIS-BS) 1330 to optimize the link.

[0126] The communication path and RIS planning module 130 provides the next RIS state (RIS-S) to the command / query format for validation (C / QF) function 1130. The command / query format for validation (C / QF) function 1130 generates a command for the next RIS state (C-RIS-S) and provides it to the network-to-RIS communication system (NW-RIS-COM) 110. This command is then sent to the RIS 20 and received by the RIS communication module (RIS-COM) 210. The RIS communication module (RIS-COM) 210 validates the command 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, so that the reflection, refraction, or redirection of the transmitted beam from the BS 10 is changed accordingly.

[0127] Next, the position of UE40 (L UE) and / or measurement reports, and / or measurement reports / CSI feedback from the RIS (e.g., of the link between the BS and the RIS or the link between the RIS and the UE), along with the resulting communication path quality, as determined by, for example, signal strength (SS) or another quality parameter provided by the RF communication capability (RF-COM) 150. Additionally, or as an alternative embodiment to FIG. 8, the network selects a RIS state that allows wide-angle scattering of the incoming signal / beam, and / or a wide-angle beam (or omnidirectional signal) is propagated by the RIS toward the UE 40. The UE 40 can receive such reflected signals, make 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 from other means such as GPS or TDOA measurements from nearby base stations). The RIS makes measurement reports on uplink signals received from the UE 40. The RIS state selected by the base station and commanded to the RIS is selected to reduce the width of the propagated signal / beam, thus using a less wide beam towards the UE 40, and / or change the angle of the beam towards the UE, and measurements are reported again. By changing the angle or further narrowing the beam based on feedback / measurements from the UE 40 using a feedback loop, a suitable communication path between the BS 10 and the UE 40 via the RIS 20 can be determined.

[0128] FIG. 9 illustrates a schematic of a communication path establishment process according to one embodiment using a beam path memory and limited local beam search.

[0129] The communication path and RIS planning module (CP / RIS-P) 130 of the BS 10 is UE ) can be stored and saved in the Location / RIS State Database (L / RIS-S-DB) 1320. This is equally valid for the embodiment using the 3D local wireless transmission model 1310 of FIG.

[0130] If in the past this model has calculated a route and the BS 10 has used this route with good results, this route is stored in the database 1320. Then, when a future UE is found near this location, the previous beam direction and state of the reconfigurable surface (REC-SF) 270 is retrieved and used, optionally with further optimization (e.g., using a local search in the RIS state) and updating of the parameters used for communication to that location.

[0131] Results from previous uses of the RIS20, i.e., the RIS state for communication with a particular location, are saved to perform a limited search for the optimal path in the real world. From this start, a limited local search process can be initiated through the RIS state. Using the RIS State Topology Map (RIS-STM), a local search can be performed from the initial selected state.

[0132] Pilot uplink signals from the UE 40 are used to determine its position in space (L UE ) can be determined.

[0133] If it is determined that beamforming in that direction directly (rather than via RIS20) is not good enough, and a (nearby) RIS (e.g., RIS20) has served a similar (not necessarily identical) location in the past, the RIS state used to communicate with that location in the past is obtained, and the RIS state is set to that value during beamforming at RIS20.

[0134] Using the RIS state topology map for that RIS stored in the RIS metadata (RIS-MD) stored in the RIS database (RIS-DB) 120, a local search of neighboring states is performed as described in the embodiment of Figure 8, and the quality of the signal is determined (e.g., based on signal strength (SS) or another quality parameter).

[0135] When adequate signal quality is achieved (e.g., a predetermined threshold is reached), the corresponding RIS state is used to communicate with the UE 40, and the RIS state and the UE location (L UE ) is stored in the location / RIS status database 1320 of that RIS 20.

[0136] RIS-compatible communication flow diagram FIG. 11 illustrates a flow diagram of a process for RIS-enabled communications in accordance with various embodiments.

[0137] This process is designed to enable the configuration and command of RIS in wireless communication systems such as 5G / 5G-NR.

[0138] The initial RIS discovery and registration process (RIS-D / R) S1101 allows a newly configured RIS to register with a network, verifying that the network has a RIS, thereby establishing the characteristics of the RIS with the network and allowing the network to effectively command the state of the RIS.

[0139] This can be achieved by a RIS installation database registration method in which a new RIS and registration method are obtained by looking up in a global RIS installation database; a RIS request for registration method in which the RIS sends a communication to the local network to send a registration method when it is first turned on; or a registration by automatic discovery of the RIS in a locality method in which the BS notes the local transmission path with variable characteristics associated with the RIS and seeks registration via various means (e.g., as described in the embodiment of Figure 5).

[0140] Next, in RIS query and command process (RIS-Q / C) S1102, the network and / or BS specifies a command or query to send to the RIS, e.g., using a RIS query and command function, formats the command / query, e.g., using a command / query formatting function for validation, sends the command / query to the RIS, e.g., using a network / BS-to-RIS transmission and reception system, and receives any response from the RIS, e.g., using a network / BS-to-RIS transmission and reception system. Further, the RIS receives the communicated query or command using a RIS communication module, checks the validity of the command / query and whether the command / query is accepted using a RIS command / query validation and acceptance function, and if the command is accepted, the RIS command module sets the reconfigurable surface of the RIS to the commanded state, and if the query is accepted, the RIS returns RIS current information data including the RIS state.

[0141] In the network control prioritization process (NC-PRIO) S1103, at the time of registration, subsequent changes or dynamic changes by command, the RIS stores the network priority to command the RIS in the RIS network priority list.

[0142] If the RIS is not currently being commanded and receives a command from the network, the RIS determines the priority of the commanding network, saves it in the RIS current information data as the current controller priority (e.g., indicated by a number as an index in an ordered list), and then executes the command.

[0143] If the RIS is currently being commanded, the RIS compares the priority of the new network issuing the command with the priority of the network currently issuing the command (currently stored as the controller priority), and if the new priority is higher, the RIS stops the command from the previous network and allows the new network to take the command.

[0144] Alternatively, lower priority networks may also be given a minimum time for their commands, and command changes may only take effect after this minimum command time has been reached.

[0145] In the communication path establishment process (CP-EST) S1104, the network and / or BS attempts to establish a communication path with the UE, which path includes one or more RISs (the RIS database indicates that the RISs are operational and the network has command authority).

[0146] This is achieved by exhaustively searching the beamforming directions and RIS states to find the optimal communication path to the UE. Once found, the BS directs its beam towards the RIS and commands the RIS to assume the correct state.

[0147] Alternatively, as shown in the embodiment of Figure 8, a beam search can be applied that supports transmission ray tracing modeling, searching for a suitable beam path (e.g., BS beam direction and RIS state) using a transmission model within the local wireless transmission model of the local environment, followed by fine-tuning using a local search of neighboring RIS states obtained from the RIS state topology map. Once found, the BS points its beam toward the RIS and commands the RIS to enter the correct state.

[0148] As yet another option, previous beam direction results, RIS state, and UE location are stored in a location / RIS state database, as shown in the embodiment of Figure 9. For a new UE location, the closest entry to this location is searched for in this database, and if close enough, the saved settings of BS beam direction and RIS state are used and fine-tuned in a local RIS state search. Once found, the BS points its beam towards the RIS and commands the RIS to enter the correct state.

[0149] In the RIS Failure Recognition (RIS-FR) process S1105, as shown in the embodiment of FIG. 10, the network and / or BS enters into the RIS database that the RIS is inoperable if the RIS returns an inoperable flag set to "true," does not return a response to a query sent to the RIS, or communication signal strength and / or other signal quality indicators indicate no actual change in RIS status.

[0150] Optionally, having reliably determined the presence of an end user UE in this way, the RIS can report this to the database / gNB so that the gNB can in turn use the capabilities of the RIS to focus the gNB's beam on this UE.

[0151] FIG. 12 illustrates a first example of an improved beam steering process according to one embodiment.

[0152] In this first embodiment, the RIS-UE 50 announces its RIS capabilities (e.g., using information provided in ProSe / Sidelink Model A discovery) so that unconnected UEs 40 can discover it. Alternatively, the unconnected UE 40 can attempt to discover the RIS-UE 50 or other RIS-UEs (e.g., using information provided in ProSe / Sidelink Model B discovery). After the RIS-UE 50 and UE 40 discover each other and are authenticated, the RIS-UE 50 and UE 40 can establish a communication link, for example, via the PC5 interface, and pair their beams to identify their specific direction (e.g., beam angle / path). The RIS-UE 50 then transmits this information (i.e., beam direction to the UE 40) to the gNB 10, which controls the RIS-UE 50. The gNB 10 knows where the RIS 20 of the RIS-UE 50 is located and the direction in which the beam must be formed to reach it. Additionally, because the RIS-UE 50 reported the beam direction from the RIS-UE 50 to the UE 40, the gNB 10 also knows the position of the UE 40 relative to the RIS-UE 50. Therefore, the gNB 10 can determine the configuration of the RIS 20 (e.g., reflection / refraction angles and redirected beam angles) to directly reach the UE 40. This is illustrated in FIG. 12. In FIG. 12, the RIS configuration refers to, for example, the reflection / refraction / redirection angles achieved by the orientation of the RIS 20 in space.

[0153] Improved beam steering with RIS providing SSB, synchronization, and system information FIG. 13 illustrates a schematic example of an improved beam steering process according to another embodiment.

[0154] In this embodiment, the gNB 10 transmits system information (SI) to the RIS 20. The system information is similar to a synchronization signal on the physical broadcast channel (PBCH) used to broadcast basic system information within a cell of a cellular radio access network. The access device (in this case, the gNB) drives the RIS as if it were distributing its own synchronization signal, either directly from the CU or via the DU. The system information includes a primary synchronization signal (PSS), a secondary synchronization signal (SSS), and a master information block (MIB) broadcast on the PBCH channel. To emulate the different synchronization signal bursts or blocks (SSBs) used in 5G and broadcast in different directions via different beams, the gNB 10 transmits such RIS SSBs to the RIS 20.

[0155] For example, in Figure 13, gNB 10 transmits four RIS SSBs to RIS 20 at times t0, t1, t2, and t3 using a single beam toward RIS 20. As shown in Figure 13, gNB 10 can change the RIS state in synchronization with the time the RIS SSBs arrive at RIS 20 so that the RIS SSBs are reflected / refracted / redirected in different directions. Here, at time t0', the RIS SSB is broadcast in the highest beam direction, at time t1', the RIS SSB is broadcast in the second highest beam direction, at time t2', the RIS SSB is broadcast in the second lowest beam direction, and at time t3', the RIS SSB is broadcast in the lowest beam direction.

[0156] When the UE 40 receives the RIS SSBs, it measures the signal-to-noise ratio (SNR) as shown in the time-dependent diagram on the right side of FIG. 13. This diagram shows that the first SSB broadcast at time t0' was received with the second lowest SNR, the second SSB broadcast at time t1' was received with the highest SNR, the third SSB broadcast at time t2' was received with the second highest SNR, and the fourth SSB broadcast at time t3' was received with the lowest SNR. The UE 40 selects the SSB with the highest SNR to establish a communication link with the gNB 10 via the RIS 20. This can be achieved by assigning individual parameters (e.g., time, frequency, preamble, or code) to each beam and using these parameters to specify the beam during the initial random access procedure.

[0157] In one example, the gNB 10 can continue to transmit RIS SSBs toward the RIS 20, and the gNB 10 can continue to switch the RIS state accordingly to continue emulating a synchronization signal. If the UE 40 moves, the UE 40 can inform the gNB 10 of the SNR received for each RIS SSB, so the gNB 10 can adjust the RIS state accordingly to ensure a good connection between the gNB 10 and the UE 40 via the RIS 20. Note that because SSBs before reflection / refracting / redirection have nearly the same (uniform) SNR, while SSBs after reflection / refracting / redirection exhibit a non-uniform SNR distribution, the UE 40 can distinguish between the SSB before reflection / refracting / redirection (times t0, ..., t3 in FIG. 13) and the SSB after reflection / refracting / redirection (times t0', ..., t3').

[0158] In one example, the system information associated with the RIS 20 (e.g., MIB or System Information Block (SIB1)) includes information about the fact that the gNB 10 is transmitting this signal via the RIS 20. This may be, for example, a bit that is either 0 or 1. The system information associated with the RIS 20 may also include information about the parent gNB 10 that steers the RIS 20. For example, the parent node's Physical Cell ID (PCI) may be included. Such information is used by the UE 40 to determine joining / communication via the RIS 20.

[0159] Improved CSI and reduced interference when using RIS In another embodiment, channel state information (CSI) can be enhanced. In wireless communications, CSI refers to the known channel characteristics of a communications link. CSI describes how a signal propagates from a transmitter to a receiver and represents, for example, the combined effects of scattering, fading, and power attenuation over distance, e.g., obtained by a channel estimation process. CSI allows transmissions to adapt to current channel conditions, which is essential for achieving reliable communications with high data rates, e.g., in multi-antenna systems.

[0160] Therefore, when a gNB transmits to a UE, it can use a CSI reference signal (CSI-RS) to understand the channel characteristics and the quality (or poorness) of the communication link. The gNB transmits the CSI-RS, and the UE receives and reports its values. In one example, the CSI-RS is transmitted every two resource blocks (SSBs). The CSI-RS can be periodic, semi-persistent, or aperiodic (e.g., transmitted in a downlink control information (DCI) message).

[0161] In one example, zero-power CSI-RS is provided as time / frequency slots where the gNB informs the UE that nothing is being transmitted. These slots can be used by the UE for interference management. Based on the received signal, the UE can select the optimal precoding matrix for the gNB's antenna steering, for example, by using a given codebook of precoding matrices. There are two types of codebooks: Type 1 is coarse (e.g., for a single user) and Type 2 is broad (e.g., for multi-user multiple-input multiple-output (MU-MIMO) systems). In the uplink direction, CSI may not be necessary because the gNB can track the quality of the received signal and instruct the UE accordingly.

[0162] As an alternative, instead of CSI-RS, current embodiments may also use Sounding Reference Signals (SRS), which are reference signals transmitted by the UE in the uplink direction and used by the gNB to estimate the quality of the uplink channel over a wider bandwidth, for example for scheduling purposes.

[0163] In the case of RIS, the gNB is interested in knowing the channel to the UE via the RIS.

[0164] In one example, an increased number of time slots (e.g., n) are allocated for transmitting CSI-RS when the UE connects via the RIS. For example, n=3 slots. While the reference signal is the same in all n slots at the time of transmission, the gNB can control the RIS so that it has slightly different reflection / refraction / redirection RIS coefficients in these n slots. For example, when n=3, the first slot uses the currently considered optimal reflection / refraction / redirection RIS coefficients and gNB-RIS beamforming, while the other two slots use slightly different reflection / refraction / redirection RIS coefficients and gNB-RIS beamforming. The purpose is to allow the UE to assist the gNB in ​​identifying the direction in which the RIS should be steered (i.e., reflection / refraction / redirection RIS coefficient) and / or the manner in which the gNB should be steered towards the RIS in order to maintain a good connection.

[0165] The above procedure may be performed for each resource block, or the beam / RIS configuration may be slightly adapted for CSI-RS transmitted on different resource blocks.

[0166] Estimating the quality of backhaul links independent of access links Figure 14 schematically shows a network including a gNB10 communicating with a control module of RIS20 (RIS-CM260) (via a control link between NW-RIS-COM110 in the gNB and RIS-COM210 in the RIS) and communicating with one or more UEs40 (via a backhaul link between RF-COM50 and RIS-FS270 in the gNB or via an access link between the RIS-FS and RF-COM401 of each UE).

[0167] When the gNB 10 communicates with the UE 40 via the RIS 20, the route passes through two links: a backhaul link and an access link. However, only one set of CSI feedback covering both links is received from the UE. If the link quality is poor, it is unclear which link is causing the problem and needs to be adjusted. A means is needed to estimate the quality of the backhaul link independently of the access link to each UE.

[0168] In some scenarios, the backhaul link and the control link operate in the same operating band. Thus, 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 steered according to a CSI dialogue between the gNB and the RIS-CM. When the gNB wishes to communicate with a UE via the RIS, it establishes a CSI dialogue with the RIS to allocate appropriate communication resources to the UE and steer the access beam. This can be explained by assuming that the gNB can ignore the contribution of the backhaul link because the backhaul link is managed independently via the RIS-CM CSI dialogue. This is appropriate if the CSI dialogue with the RIS-CM reports a good channel, or at least a channel that performs significantly better than that reported in the UE CSI dialogue.

[0169] This first embodiment takes advantage of the fact 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 the backhaul by equalizing the received signal according to readings from the CSI signal sent to the gNB by the RIM-CM over the control link, for example. This may provide some headroom for link degradation.

[0170] For example, if the same band is used for uplink and downlink, as in TDD mode, the gNB can also pre-equalize the downlink signal, meaning that the UE essentially receives a signal that is only degraded by the access link.

[0171] The scenarios described in the above embodiments are limited. It is of interest to be able to support multi-band repeater operation without requiring a multi-band link to the RIS-CM 260. There are also applications where the RIS-FS 270 and the RIS-CM share the same band but are served by different transmission / reception points or different gNBs, thus requiring different beams. Therefore, the second embodiment takes advantage of the fact that the backhaul link is shared by many UEs, each with its own access link. If the quality of the backhaul link is poor, the same channel degradation is reflected in the CSI information from all UEs. This indicates to the base station that the problem is in the backhaul link and not the access link.

[0172] If the quality of the backhaul link can be assumed to be good, then as a good approximation, the contribution of the backhaul link to the overall link quality can be ignored, since the CSI information provides more information about the access link. For example, this is the case when both the repeater and the base station are in fixed locations. In other cases, for example, when the repeater is moving or when the backhaul link needs to be established first, the quality of the backhaul cannot be assumed to be good and some means of obtaining quality is required.

[0173] As an example of how this works, for the downlink, UEs 40-1, 40-2, 40-3, and 40-4 all return CSI feedback in the form of a 4-bit CSI index, which indicates the modulation and code rate the UE can successfully demodulate. A lower value indicates a worse channel (0 indicates data cannot be demodulated), while a higher value indicates better channel quality. Assuming the UEs all have similar demodulation capabilities, the different values ​​provide a measure of the relative performance of the backhaul and access links, and using a simple heuristic approach, the gNB can determine which beams to adjust. For example, given that relays exist to provide better service to UEs outside the gNB's direct range, returning uniformly low values ​​indicates a problem with the backhaul. Conversely, if any UE reports a good-quality channel, the backhaul must also be good, while for the other UEs, the problem lies in the access link. Therefore, one simple approach is to consider the maximum quality reported by the UE as the quality of the backhaul. When different CQI tables are used by the UEs, the backhaul is assigned the quality corresponding to the highest reported efficiency. If it is below the threshold, the backhaul is adjusted, and if it is not below the threshold, the access link is adjusted.

[0174] The fluctuations will suggest themselves depending on the exact scenario. For example, if the reported link quality is variable and suggests movement, then if there is no correlation between the fluctuations from different UEs, the backhaul link can be assumed to be stable, and again, the maximum reading for a given period can be taken as representative of the quality of the backhaul link. On the other hand, if the fluctuations have a strongly correlated component, this suggests that the backhaul link has problems due to movement or other causes.

[0175] A similar approach can be taken for the uplink using the CSI signal transmitted by the UE. By assigning a quality index similar to the CSI index returned by the UE, the gNB can develop a comparative measure of the uplink channels and use similar heuristics to decide whether to adjust the backhaul or the separate access link.

[0176] The above embodiments rely on the presence of many UEs. A third embodiment addresses the case where only one UE is active or where the base station needs to steer both the backhaul link and the access link based on feedback from a single UE. When a single UE is involved, no comparison can be made to determine the state of the backhaul channel separately from the access link. This also applies when the number of UEs is greater than one but insufficient to make a meaningful comparison.

[0177] In an alternative to the first embodiment, the base station uses CSI information to first adjust the access downlink for optimal quality. If the quality is still insufficient (i.e., the CSI information still reports poor quality), it uses the CSI information to adjust the backhaul link. This assumes that the access link changes frequently and is therefore likely to be the cause of changes in overall link quality. The UE also adjusts the access uplink to its maximum extent, and any unresolvable changes may indicate a problem with the backhaul. On the other hand, the backhaul link changes relatively slowly, and this change should be made as a last resort. This algorithm can be modified to suit different situations. For example, in a vehicular scenario, it can be assumed that the backhaul changes frequently and the access link is more stable.

[0178] In an alternative to the second embodiment, the base station 10 independently observes the impact on the CSI reported by the UE and (slightly) adjusts the backhaul link and the access link. For example, at time t0, the base station observes the CSI (improvement / deterioration) reported by the UE and adjusts the backhaul (e.g., beam alignment) while keeping the access link in its current configuration; at time t1, the base station observes the CSI (improvement / deterioration) reported by the UE and adjusts the access link (e.g., beam alignment) while keeping the backhaul link in its current configuration, and so on. In this alternative, the links should be adjusted independently, and the adjustment frequency for a link depends on the nature of the link. For example, if the access link is more dynamic than the backhaul link because the UE is mobile and the NCR is static, the access link should be measured more frequently. Alternatively, if the UE is static (relative to the RIS) and the RIS is mobile (e.g., a RIS mounted on a vehicle), the backhaul link should be measured more frequently.

[0179] In an alternative to the third embodiment, the base station may configure the UE with a higher CSI frequency reporting setting to ensure that the base station can guarantee the quality of both links.

[0180] In an alternative to the fourth embodiment, the base station distributes the CSI reporting requirements for the backhaul links across multiple UEs so that the quality of service for any single UE is not significantly impaired and the degradation is evenly distributed.

[0181] In an alternative to the fifth embodiment, the base station distributes the CSI reporting requirements for the backhaul link across unconnected UEs.

[0182] In a fourth embodiment, the RIS is provided with means for intercepting CSI sounding signals transmitted on the uplink and downlink of the communication path between the gNB and the UE and determining an appropriate report to send to the gNB.

[0183] For the downlink, the report is the CSI index mentioned above. One possible implementation is for the RIS-CM 260 to analyze the intercepted CSI signal and return the results to the gNB. This process is the same as the standard CSI procedure, except that the intercepted CSI signal from the communication path is used. The gNB uses this direct measure to adjust the backhaul downlink beam. In a variant approach, the RIS-CM also uses this information to adjust the backhaul uplink beam of the communication path.

[0184] For the uplink, the RIS-CM analyzes the signal transmitted by the UE and determines a metric to feed back to the gNB. The gNB compares this with its own metric obtained from the signal received via the backhaul. The difference reflects the degradation caused by the backhaul, and the gNB can use this information to update the gNB's uplink backhaul beam. It can also advise the NCR-MT on adjustments to the backhaul-uplink beam of the communication path. The signal processing that the RIS-CM must perform corresponds to the normal gNB processes. In an alternative embodiment, the RIS-CM is enabled to process the signal as a downlink signal and send the appropriate metric to the gNB.

[0185] The above embodiments rely on the presence of at least one UE to provide a measure of the backhaul uplink, which leaves open the question of how the system should behave when a repeater is first discovered, since there is no way to establish a backhaul beam at the initial UE readiness.

[0186] Therefore, in the fifth embodiment, the RIS uplink, which corresponds to the future communication path between the gNB and the UE, emits some kind of reference signal that the gNB can use to optimize the backhaul uplink beam configuration. To avoid interference, this signal should only be used in the absence of other signals. The base station provides the RIS-CM with a schedule for signal generation.

[0187] In an alternative to the first embodiment, optimized for simplicity, the emitted signal is a noise-like signal using a noise source or thermal noise from the input stage of the repeater amplifier, and the gNB can optimize the beam configuration using a measure of the received signal strength of the noise signal.

[0188] In an alternative to the second embodiment optimized for compatibility, the gNB can have the RIS-CM 260 generate or rebroadcast standard reference signals on the uplink of the backhaul link in a specific direction. For example, the gNB can request the RIS-CM to rebroadcast received signals in four directions on the backhaul uplink at times t0, t1, t2, and t3 and to transmit SSBs on the control downlink toward the RIS-CM at times t0, t1, t2, and t3. The RIS then rebroadcasts such SSBs (or other reference signals, such as CSI-RS). Alternatively, if the RIS has this capability, the gNB can generate SSBs itself and instruct the RIS to transmit them in specified directions at specified times. The gNB monitors the quality of the received reference signals (re)broadcast by the RIS, identifies the strongest signal, and uses the extracted information to adjust the backhaul link (e.g., to perform beam alignment or derive CSI for the link).

[0189] In all alternatives, the RIS is activated (eg, transmits a reference signal) only after the RIS-CM receives a control signal indicating the need for backhaul link configuration.

[0190] In principle, this embodiment can also be used when the UE is served in a similar manner as disclosed in the first embodiment, the main difference being that in this fifth embodiment, the CSI signals are received over the backhaul rather than the control link.

[0191] In a further embodiment related to the third embodiment, the base station (or primary station) broadcasts a channel state information reference signal (CSI-RS) through different beams associated with the secondary stations (or RIS or NCR) in a first step a. In other words, the base station transmits the CSI-RS in a wide-beam broadcast and commands the secondary stations to rebroadcast the CSI-RS through different directional beams in different directions. Since the UE returns CSI for each received beam containing the CSI-RS, the primary station has sufficient information to select an optimal beam for connecting to the UE in the access link, and this optimal beam a is denoted BBA. In a second step b, the primary station transmits itself CSI-RS through N different beams and commands the secondary stations to rebroadcast it through BBA. The UE recognizes the N CSI-RS, collects CSI, and transmits the CSI to the base station. The base station has sufficient information to configure the backhaul link (i.e., to select an optimal beam for the backhaul link). This procedure then requires two steps to configure the access and backhaul links between the primary station and the UE with a single secondary station. In a multi-hop configuration with k secondary stations, k+1 steps are required, each involving measurements on N beams / CSI-RS.

[0192] In a variant of a related embodiment, the base station broadcasts the CSI-RS via one base station beam at a time, and for each of them, the secondary station needs to rebroadcast it via a different beam at the secondary station. If the primary station has N beams for distributing the CSI-RS and there are M beams for distributing the CSI-RS at the secondary station, a total of M*N CSI-RS measurements are required, and the UE must report M*N CSIs. This procedure also allows the base station (primary station) to determine the optimal beam for both the access link and the backhaul link.

[0193] In some situations, the secondary station may be a static device, while in other cases it may be a mobile repeater, i.e., a repeater mounted on a vehicle, UAV, or satellite. Such mobile devices move along a known path or trajectory. In some cases, the location of the static access device may also be somewhat known. Therefore, in a further embodiment, the alignment of the backhaul link follows a two-step approach, where in a first step, a coarse alignment is performed based on a rough knowledge of the location of the secondary station, and in a second step, a fine alignment is performed based on one of the above embodiments. In the first step, a coarse backhaul link alignment between the primary station (base station / gNB) and the secondary station (mobile repeater) is determined based on the location of the primary station and the location of the secondary station. This requires configuration of the location / trajectory / route of the secondary station at the primary station, which is performed by AMF or OAM.

[0194] In general, the above embodiments can be managed as a successive iterative procedure where the gNB and UE align their antenna beams towards more optimal positions at each step, with priority given to aligning the backhaul link or the access link depending on the operating scenario.

[0195] The above embodiments can also be used independently or in combination with other solutions, for example, the fifth embodiment may be used as a first solution step for the initial configuration of the backhaul links in the RIS, and subsequent operations (e.g., the configuration of the access links) may be based on other techniques.

[0196] Interference Avoidance In another embodiment, interference coordination / mitigation is achieved by reusing the RIS across multiple base stations (gNBs). In particular, to avoid two access devices causing interference by simultaneously operating one or more RIS elements on the same / similar frequencies, the RIS can inform one or more of the access devices of the frequencies and / or schedules used / requested / operated by one or more other access devices, for example, using the RIS communication module 210 (e.g., by using a query / control communication protocol or by sending notifications / measurements). The RIS is equipped with one or more sensors to detect interference. If interference is detected, it is reported to one or more of the access devices, or the RIS changes its state or ceases operation. The RIS uses measurement information from one or more sensors and / or its built-in UE functions to identify the access device from which the signal originates and / or calculates the angle of arrival of the interfering signal and reports this 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, is also reported to one or more access devices.

[0197] When a gNB uses a RIS, its range is extended and it may interfere with other areas. A gNB notifies a second gNB of its desire to use the RIS, including the desired coverage range, frequency, and / or timing. This is done, for example, via the Xn control plane interface between gNBs defined in 3GPP. The second gNB can confirm / deny this use. The Xn interface is also used to synchronize the clocks of the two gNBs and / or coordinate their schedules for using the RIS.

[0198] A UE connected to a second gNB can measure a given interference level caused by the RIS currently controlled by the first gNB. The UE can inform the second gNB of the interference level and the source of the interference. The gNB can indicate the source of the interference if it transmits a CSI-RS linked to the RIS with its identifier. In that case, the second gNB can inform the first gNB using the Xn control plane interface.

[0199] Another consideration is the fact that in the above embodiment, the gNB can communicate with only one UE at a time using the RIS. However, existing gNBs are capable of MIMO operation by using multiple beams. In some scenarios, it is desirable to control a RIS that can handle multiple beams simultaneously. In one embodiment, this can be done when the RIS behaves differently depending on the characteristics (e.g., frequency, polarization, etc.) of the incident electromagnetic (EM) wave. With such a RIS, the gNB can control the RIS so that the reflection / refraction / redirection angles depend on the EM characteristics of the incident wave, thereby allowing the gNB to communicate with two different UEs simultaneously through the same RIS. The procedure is as follows: 1) The gNB sets the RIS to a given state for a given period of time. This state refers to the refraction / reflection / redirection characteristics that depend on the specific characteristics (e.g., frequency, polarization, etc.) of the incident EM wave. 2) The gNB transmits two or more beams toward the RIS. Each beam is characterized by specific characteristics (e.g., frequency, polarization, etc.) that are treated differently depending on the current RIS state, which causes the beams to be split at the RIS. In this procedure, the RIS state is a state in which two or more beams transmitted from the gNB to the UE via the RIS are reflected / refracted / directed differently by the RIS, so that when the gNB transmits two or more beams toward the RIS, they reach two or more UEs at different locations simultaneously. Similar behavior can also be applied to smart repeaters.

[0200] In summary, a system and method for determining and controlling a reconfigurable relay device (e.g., a reconfigurable intelligent surface (RIS) or smart repeater) have been described. The reconfigurable relay device is registered, and a wireless communication path is established from the network (e.g., an access device) to an end device via the reconfigurable relay device, maintaining optimal quality for both the backhaul and access links by independently evaluating the link quality of each link. The network registers the reconfigurable relay device and determines the parameters required for its control. Control is achieved through verified and accepted commands and queries. The relay state of the relay device is set such that the beam of the wireless communication path is correctly steered to the end device.

[0201] While the present invention has been illustrated and described in detail in the drawings and the foregoing description, such illustration and description should be considered illustrative or exemplary and not restrictive. The present invention is not limited to the disclosed embodiments. The present invention may 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-exchange (V2X) communication), V2X devices, Internet of Things (IoT) hubs, IoT devices (such as low-power medical sensors for health monitoring, medical (emergency) diagnostic and treatment devices for hospital or first responder use), virtual reality (VR) headsets, etc.

[0202] A BS is 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 within a geographic coverage area (indoor or outdoor).

[0203] The RIS is created by using a smart device (e.g., a smart TV or a smart infrared panel) with a hardware component that is considered a good reflector (e.g., a large glass screen or panel). The RIS can also be embedded in objects such as billboards, building facades, posters, floor tiles, roofs, and walls. Furthermore, in the above embodiments, the RIS can be replaced by a smart repeater, an RF repeater, or any relay device with controllable relay or reflecting functionality.

[0204] Furthermore, at least some of the above embodiments may be implemented to provide network equipment for 5G / 6G / xG cellular networks or a new product class of (low / mid-cost) reconfigurable intelligent surfaces that improve cellular network coverage, reliability, and speed.

[0205] Other variations of the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the use of an "a" or "an" element does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. The above description details particular embodiments of the invention. However, it will be understood that no matter how detailed the above description may appear herein, the invention can be embodied in many ways and is therefore not limited to the disclosed embodiments. Furthermore, the use of certain terms in describing particular features or aspects of the invention should not be construed as implying that the terms are redefined herein to be limited to include any particular feature or aspect of the invention with which they are associated. Furthermore, it will be understood by those skilled in the art that the terms used herein, and in particular in the appended claims, are generally intended to be "open" terms. For example, the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "comprising" should be interpreted as "including but not limited to," and so forth. Furthermore, where a particular number of introduced claim recitations is intended, such intention will be expressly stated in the claim, and those skilled in the art will understand that, in the absence of such statement, no such intention exists. For example, to aid in understanding, the following appended claims may include 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 meaning that introducing a claim recitation with the indefinite article "a" or "an" limits any particular claim containing such an introduced claim recitation to implementations containing only one of such an enumeration, even if the same claim also contains the introductory phrases "one or more" or "at least one." Instead, the indefinite article should be construed to mean "at least one" or "one or more." The same applies to the use of definite articles used to introduce claim recitations. Furthermore, when language similar to "at least one of A, B, and C" is used, such configuration is generally intended to have the meaning that one of ordinary skill in the art would understand the language; for example, "a system having at least one of A, B, and C" includes, but is not limited to, systems having only A, only B, only C, A and B, A and C, B and C, and / or A, B, and C, etc. Moreover, those skilled in the art will understand that virtually any disjunction and / or phrase presenting two or more alternative terms, whether or not it appears in the description, claims, or drawings, should be understood to contemplate the possibility of including one, either, or both of the terms. For example, the phrase "A or B" is understood to include the possibilities of "A" or "B" or "A and B."

[0206] The described operations, such as those shown in Figures 2 and 11, may be implemented as program code means of a computer program and / or as dedicated hardware in the associated network devices or functions. The computer program may be stored and / or distributed on a suitable medium, such as an optical storage medium or a solid-state medium, supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless communication systems.

Claims

1. 1. A method for operating a network, the network comprising a primary station communicating with a terminal station via a secondary station, the secondary station relaying 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 comprises the steps of: managing the access link according to a measured quality or an indirect estimate of channel quality between the primary station and the terminal station; managing the quality of the backhaul link based on an indirect estimation or according to a measured quality; A method comprising:

2. 1. A method for operating a primary station in a network, the primary station communicating with one or more terminal stations via secondary stations, the secondary stations relaying signals exchanged between the primary station and the one or more terminal stations, the secondary stations 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 the steps of: the primary station managing access according to a measured quality between the primary station and the terminal station; the primary station managing the quality of the backhaul link between the primary station and the secondary station based on indirect estimation or according to a measured quality; A method comprising:

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

4. The method of claim 3 , wherein the control link and the backhaul link are exchanged with overlapping bandwidth or the same bandwidth.

5. The method of claim 3 , wherein the control link and backhaul link are exchanged in contiguous bandwidth.

6. 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; 3. The method of claim 1, wherein the access link is managed according to channel state information exchanged between the primary station and the terminal station, and the backhaul link is managed according to channel state information exchanged between the primary station and the secondary station for the control link.

7. The method of claim 1 or 2, wherein the indirect estimation of the backhaul link is performed on active link estimation statistics.

8. The active link estimation statistics include: Maximum access link quality value, the maximum access link quality value compared to the threshold, the maximum access link quality value compared to the average of the access link quality values; Average access link quality value, the average access link quality value compared to the threshold, the variance of the quality values ​​of the sample or all access links, Variation of access link quality values ​​over time, The method of claim 7, comprising at least one of:

9. The method according to claim 7 or 8, wherein the indirect estimation of the backhaul link is performed on estimated statistics of active links when the number of terminal stations exceeds a predefined threshold.

10. 3. The method of claim 1, wherein the primary station initially adjusts an access link with the terminal station, determines a change in the link quality value after this initial adjustment, and decides whether to adjust the backhaul link at least upon this determination of the change in the link quality value.

11. The method of claim 10 , wherein the primary station adjusts the backhaul link if it is determined that the link quality value will not change substantially.

12. 3. The method of claim 1, wherein the primary station first adjusts one of the backhaul link with the secondary station or the access link with the terminal station, determines a change in the link quality value after this initial adjustment, and decides whether to adjust the other of the backhaul link or the access link with this determination of at least the change in the link quality value.

13. The method according to claim 1 , wherein the frequency of reporting the link access quality depends on whether the terminal station communicates with the primary station via a secondary station.

14. The method of claim 13 , wherein the reporting frequency of the link access quality is higher when the terminal station communicates with the primary station via a secondary station.

15. 3. The method of claim 1, wherein the reporting frequency depends on whether the terminal station communicates with the primary station via a secondary station and on the number of terminal stations communicating with the primary station via the secondary station.

16. 1. 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 relaying 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 includes the steps of: monitoring, by the secondary station, a probe signal from the primary station for the terminal station and / or a probe signal from the terminal station to the primary station; generating a backhaul link quality report to send to the primary station; A method comprising:

17. The method of claim 16 , wherein the backhaul link quality report is transmitted over a control link between the secondary station and the primary station.

18. The method of claim 16 , wherein the backhaul link quality report is transmitted over the backhaul link to the primary station.

19. 17. The method of claim 16, wherein the probe signal is one of noise, thermal noise, a pseudorandom sequence, a reference signal, or a pilot signal.

20. a secondary station operating in a network comprising a primary station communicating with terminal stations via the secondary station, the secondary station relaying signals exchanged between the primary station and one or more of 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 secondary station comprises a controller for monitoring a channel state information signal from the primary station for the terminal station, the controller controlling a transmitter to transmit a backhaul link quality report to the primary station.

21. 1. A method for operating a secondary station in a network, the network comprising a primary station communicating with a terminal station via a secondary station, the secondary station relaying 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 transmitting a probe signal to the primary station such that an estimation of the quality of the backhaul link is made at the primary station.

22. 22. The method of claim 21, wherein the probe signal is a reference signal inserted by the secondary station into the signal transmitted on the backhaul link.

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

24. 24. The method of any one of claims 21 to 23, wherein the step of transmitting the probe signal occurs during a period of low activity.

25. 25. The method of claim 24, wherein the period of low activity is a time period when no signal is expected.

26. 25. The method of claim 24, wherein the low activity period is a time window established by the primary station during which no other probe signals are expected.

27. 27. The method of any one of claims 21 to 26, wherein the probe signal is one of 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 relaying 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 an access link; The secondary station comprises a transmitter for transmitting a probe signal to the primary station so that an estimation of the quality of the backhaul link is made at the primary station.

29. a primary station operating in a network, the primary station communicating with a terminal station via a secondary station, the secondary station relaying 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 an access link; the primary station receiving a probe signal from the secondary station and estimating a backhaul link quality based on measurements of the probe signal; The primary station adjusts the backhaul link based on the backhaul link quality.

30. 30. The primary station of claim 29, wherein the primary station also adjusts the access link based at least on the backhaul link quality.

31. 1. A wireless network comprising a primary station communicating with terminal stations via secondary stations, the secondary stations relaying signals between the primary station and one or more of the terminal stations, the secondary stations exchanging data with the primary station over a backhaul link and exchanging data with the terminal 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 according to a measured quality or an indirect estimation of a channel quality between the primary station and the terminal station; a backhaul link estimator for indirectly estimating a quality of the backhaul link between the primary station and the secondary station; a backhaul link manager that adjusts the backhaul link based on an indirect backhaul link estimation or according to a measured quality; A wireless network comprising:

32. The adjustment of each access link is Adjusting the direction and shape of the radio beam between the secondary station and the terminal station; Selection of modulation format and coding rate; Symbol rate selection, or Selection of operating bandwidth, 32. The wireless network of claim 31, independently comprising one or more of:

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

34. 32. The wireless 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, and both links are managed according to channel state information exchanged between the primary station and the secondary station for the control link.

35. 32. The wireless network of claim 31, wherein multiple access links are managed by the primary station, and the quality of the backhaul link is estimated as a function of measured qualities of the multiple access links.

36. 36. The wireless network of claim 35, wherein for the multiple access links, the backhaul link quality is estimated to be equal to the maximum of the measured qualities.

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

38. A single access link is managed by the primary station, and a single measured quality is used to adjust both the backhaul link and the access link in separate steps, checking each step to measure the impact on the measured link quality, and optionally reversing the adjustment if the measured link quality deteriorates, and the primary station decides which link to adjust according to the measured link quality and other parameters, wherein the other parameters include: the impact of recent adjustments on the measured link quality; Operation scenario, 32. The wireless network of claim 31, comprising one or more of:

39. 39. The wireless network of claim 37 or 38, wherein the operating scenarios include at least one of the following: the secondary station is fixed with respect to the primary station; the secondary station is mobile with respect to the primary station; the secondary station is fixed with respect to the terminal station; and the secondary station is mobile with respect to the terminal station.

40. 32. The wireless network of claim 31 , wherein the secondary station comprises means for reading channel state information signals transmitted by the primary station and the connected terminal station and for sending reports to the primary station, where the reported information is used to derive measures of quality of each of a backhaul downlink and an access uplink.

41. 41. The wireless network of claim 40, wherein the secondary station transmits the channel state information signal to the primary station.

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

43. 41. The wireless network of claim 40, wherein the secondary station additionally comprises means for exchanging channel state information signals with the primary station over the backhaul link, the primary station using the received channel state information signals to derive a measure of a quality of a backhaul uplink.

44. 44. A wireless network according to any one of claims 31 to 43, wherein uplink and downlink channels operate in the same radio band, and wherein the primary station uses quality measurements of an associated uplink channel to estimate the quality of a downlink channel, and vice versa.

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