SYNCHRONIZATION METHODS IN REPEATER-ASSISTED NETWORKS

FIELD

The present disclosure relates to wireless communications, and in particular, to synchronization methods in repeater-assisted networks.

INTRODUCTION

The Third Generation Partnership Project (3GPP) has developed and is developing standards for Fourth Generation (4G) (also referred to as Long Term Evolution (LTE)) and Fifth Generation (5G) (also referred to as New Radio (NR)) wireless communication systems. Such systems provide, among other features, broadband communication between network nodes, such as base stations, and mobile wireless devices (WD), as well as communication between network nodes and between WDs. Sixth Generation (6G) wireless communication systems are also under development.

To increase the data rate and support the increasing number of WDs, different methods are considered, among which network densification and millimeter wave (mmw) communications are the dominant ones. Network densification refers to the deployment of multiple access points of different types in, e.g., metropolitan areas. Particularly, it is expected that in future small nodes, such as relays, lABs, repeaters, etc., will be densely deployed to assist the existing macro-BSs.

During the development of 3 GPP Technical Releases 16 and 17 (3 GPP Rel-16 and 3 GPP Rel-17), IAB (Integrated Access and Backhaul) has been well studied as a main relaying technique in 5G. These considerations will continue in 3GPP Rel-18 on Mobile IAB. Here, using decode- and-forward relaying technique, the IAB may well extend the coverage and/or increase the throughput. However, IAB may be a relatively complex and expensive node and thereby, depending on the deployment, alternative nodes with low complexity/cost for, e.g., blind spot removal, may be required. Here, a candidate type of network node is the radio frequency (RF) repeater which amplifies and forwards any signal that the RF repeater receives. RF repeaters have seen a wide range of deployments in 2G, 3G and 4G to supplement the coverage provided by regular full-stack cells. However, an RF repeater lacks accurate beamforming which may limit its efficiency in, for instance, frequency range 2 (FR2).

With this background, a study in 3GPP Rel-18 took place May to August 2022 in which the potentials and the challenges of network-controlled repeaters were evaluated. However, it is generally understood that a network-controlled repeater is a normal repeater with beamforming capabilities. In this way, the network-controlled repeater should be considered as a network- controlled “beam bender” relative of the network node. As such, it is logically part of the network node for all management purposes, i.e., it is likely that the network-controlled repeater is deployed and under the control of the operator. A network-controlled repeater is based on an amplify-and- forward relaying scheme, and it is likely to be limited to single-hop communication in stationary deployments with focus on FR2. In particular, the network-controlled repeater summary and Study Item Description (SID) considers the following scenarios and assumptions for the study -item:

Network-controlled repeaters are inband RF repeaters used for extension of network coverage on FR1 and FR2 bands, while FR2 deployments may be prioritized for both outdoor and 021 scenarios;

For only single hop stationary network-controlled repeaters;

Network-controlled repeaters are transparent to WDs; and

Network-controlled repeater may maintain the network node-repeater link and repeater-UE link simultaneously.

Cost efficiency is a consideration for network-controlled repeaters.

Also, the study-item will include identifying which side control information is necessary for network-controlled repeaters including assumption of maximum transmission power:

Beamforming information:

Timing information to align transmission / reception boundaries of network- controlled repeater;

Information on uplink-downlink (UL-DL) time division duplex (TDD) configuration;

ON-OFF information for efficient interference management and improved energy efficiency; and

Power control information for efficient interference management (as the 2 ^nd priority).

Moreover, the study-item will study and identify layer 1/layer 2 (L1/L2) signaling (including its configuration) to carry the side control information

Finally, the study-item will study the following aspects of network-controlled repeater management:

Identification and authorization of network-controlled repeaters.

Network-controlled Repeater

How a network-controlled repeater will be designed and how it will communicate with the network is still not clear. FIG. 1 is an example schematic diagram of one possible network- controlled repeater in a network. In this example, the network-controlled repeater consists of three principal building blocks, the Modem, the Controller module, and the Repeater module section (depicted as the two amplifiers in FIG. 1). The network-controlled repeater is equipped with an antenna configuration, where a signal is first received in downlink (or uplink), and, e.g., after power amplification, transmitted further downlink (or uplink). Since the Repeater module only amplifies and (analogously) beamforms the signal, no advanced receiver or transmitter chains are required, which reduces the cost and energy consumption compared a typically more complex Transmission and Reception Point (TRP). In a simple architecture, different antenna modules are used for the service and access sides, i.e., the antennas targeting the network node and WDs, respectively, whereas a more complex architecture, including self-interference cancellation, would allow for using the same antenna modules for both sides.

The modem module is able and used to exchange control and status signaling with a network node that is controlling the network-controlled repeater. For this, the modem module supports at least a sub-set of WD functions. Network-controlled repeater control and status information is further exchanged between the modem module and the controller module. The modem module might be equipped with antennas separated from the antennas used by the repeater module; but in most configurations, the modem module and repeater module will share antenna configurations.

The controller module may be used to control the repeater module by, for example, providing beamforming information, power control information, etc. The controller module is connected to the network through the modem module such that the network may control the controller module and, in that way, control the repeater module.

The repeater module amplify-and-forward operation is controlled by the control module. The controller module could also be directly responsible for the beamforming control on the service antenna side, i.e., to/from served WDs. In an alternative, the beamforming on the service antenna side is operated by the repeater module under control of the controller module. On the access antenna side, i.e., to/from the controlling network node, the modem module could be directly responsible for the beamforming control. In an alternative, the beamforming on the access antenna side is operated by the Repeater module under control of the controller module and/or modem module.

In one configuration, the modem module and the repeater module do not only share an antenna configuration but also parts of the (analog) transmitter and/or receiver, such as power (transmit) amplifier and/or receiver amplifiers and/or filters.

The modem module and the repeater module could be operating at the same or different frequencies. For example, the repeater module could operate at a high frequency band (FR2) and the modem module could be operating at a low frequency band (FR1). In another example, the modem module could communicate with the network node and exchange, e.g., side control information on an RF carrier other than the RF carrier used on the access and/or service link by the repeater module. Here, the service link is used for backhauling and can also be referred to as backhaul link, or is considered to include the backhaul link. The terms service link and backhaul link are therefore interchangeable in many of the explanations in this disclosure. It is furthermore assumed that the repeater’s control link is-may be the same link as the service/backhaul link, and the service link is used for control and can also be referred to as control link, or is considered to include the control link. The terms service link and control link are therefore interchangeable in many of the explanations in this disclosure. Intelligent reflecting surface

Intelligent reflecting surfaces (IRS), also known as Reconfigurable Intelligent Surfaces (RIS), is emerging technology that is capable of intelligently manipulating the propagation of electro-magnetic waves. RIS has a 2-dimensional array of reflecting elements, where each element acts as a passive reconfigurable scatterer, i.e., a piece of manufactured material, which may be programmed to change an impinging electro-magnetic wave in a customizable way. Such elements are usually low-cost passive surfaces that do not require dedicated power sources, and the radio waves impinged upon them may be forwarded without the need of employing power amplifier or RF chain. Moreover, RISs may potentially work in full duplex mode without significant selfinterference or increased noise level and require only low-rate control link or backhaul connections. RISs may be flexibly deployed due to their low weight and low power consumption. RIS is of interest in stationary or low-mobility networks, in which the transmission parameters may be well planned and, e.g., blockages/tree foliage is bypassed through RIS -assisted communication.

There are still ambiguities about the detailed differences of the network-controlled repeaters and RISs. An explanation is that a RIS is a network-controlled repeater with negative amplification. In general, RIS is expected to be a simpler and cheaper node with less focused beamforming capability/accuracy and without active amplification. That is, RIS may be capable of signal reflection via adapting a phase matrix while the network-controlled repeater is capable of advanced beamforming with power amplification. Also, delay wise, RIS may have slightly lower latency, compared to network-controlled repeater. In 3GPP, RIS-assisted communication has been recently suggested by some companies as a possible technology to be considered in a 3GPP Rel-18 network-controlled repeater study -item. For instance, RIS has been discussed in the 3GPP TSG RAN Rel-18 workshop, June 2021. Then, a network-controlled repeater is likely to be a superset of the RIS in 3GPP specifications, it is not unlikely that RIS-specific features are discussed in the 3GPP Rel-18 study -item on network-controlled repeaters.

An RIS may have a design that is similar to the design of the network-controlled repeater shown in FIG. 1, but without the signal amplification step in the Repeater module.

Multi-beam operation

Beam management procedure

In the high frequency range (FR2), multiple RF beams may be used to transmit and receive signals at a network node and a WD. For each DL beam from a network node, there is typically an associated best WD receive (Rx) beam for receiving signals from the DL beam. The DL beam and the associated WD Rx beam forms a beam pair. The beam pair may be identified through a so-called beam management process in NR. A DL beam is (typically) identified by an associated DL reference signal (RS) transmitted in the beam, either periodically, semi -persistently, or aperiodically. The DL RS may be a Synchronization Signal (SS) and Physical Broadcast Channel (PBCH) block (SSB) or a Channel State Information RS (CSI-RS). By measuring all the DL RSs, the WD may determine and report to the network node the best DL beam to use for DL transmissions. The network node may then transmit a burst of DL-RS in the reported best DL beam to let the WD evaluate candidate WD RX beams.

Although not explicitly stated in the NR specification, beam management has been divided into three procedures, shown in the example of FIG. 2:

PL Purpose is to find a coarse direction for the WD using wide network node transmit (TX) beam covering the whole angular sector;

P2: Purpose is to refine the network node TX beam by doing a new beam search around the coarse direction found in Pl; and

P3: Used for WD that has analog beamforming to let the WD find a suitable WD RX beam.

Pl is expected to utilize beams with rather large beamwidths and where the beam reference signals are transmitted periodically and are shared between all WDs of the cell. Typically, reference signals used for Pl are periodic CSLRS or SSB. The WD then reports the N best beams to the network node and their corresponding reference signal received power (RSRP) values.

P2 is expected to use aperiodic/or semi -persistent CSI-RS transmitted in narrow beams around the coarse direction found in PL

P3 is expected to use aperiodic/or semi -persistent CSLRSs repeatedly transmitted in one narrow network node beam. One alternative way is to let the WD determine a suitable WD RX beam based on the periodic SSB transmission. Since each SSB consists of four orthogonal frequency division multiplexed (OFDM) symbols, a maximum of four WD RX beams may be evaluated during each SSB burst transmission with one evaluation per symbol (one SSB burst includes up to 64 SSBs). One benefit with using SSB instead of CSI-RS is that no extra overhead of CSI-RS transmission is needed.

Beam indication

In NR, several signals may be transmitted from different antenna ports of a same base station. These signals may have the same large-scale properties such as Doppler shift/spread, average delay spread, or average delay. These antenna ports are then said to be quasi co-located (QCL).

If the WD knows that two of its antenna ports are QCL with respect to a certain parameter (e.g., Doppler spread), the WD may estimate that parameter based on one of the antenna ports and apply that estimate for receiving a signal on the other antenna port. For example, there may be a QCL relation between a CSI-RS for tracking RS (TRS) and the physical downlink shared channel (PDSCH) demodulation reference signal (DMRS). When WD receives the PDSCH DMRS it may use the measurements already made on the TRS to assist the DMRS reception.

Information about what assumptions may be made regarding QCL is signaled to the WD from the network node. In NR, four types of QCL relations between a transmitted source RS and transmitted target RS were defined:

Type A: {Doppler shift, Doppler spread, average delay, delay spread};

Type B: {Doppler shift, Doppler spread};

Type C: {average delay, Doppler shift}; and

Type D: {Spatial Rx parameter}.

QCL type D was introduced in NR to facilitate beam management with analog beamforming and is known as spatial QCL. There is currently no strict definition of spatial QCL, but the understanding is that if two transmitted antenna ports are spatially QCL, the WD may use the same Rx beam to receive them. This is helpful for a WD that uses analog beamforming to receive signals, since the WD needs to adjust its RX beam in some direction prior to receiving a certain signal. If the WD knows that the signal is spatially QCL with some other signal it has received earlier, then the WD may safely use the same RX beam to receive also this signal.

In NR, the spatial QCL relation for a DL or UL signal/channel may be indicated to the WD by using a “beam indication”. The “beam indication” is used to help the WD find a suitable RX beam for DL reception, and/or a suitable TX beam for UL transmission. In NR, the “beam indication” for DL is conveyed to the WD by indicating a transmission configuration indicator (TCI) state to the WD, while in UL the “beam indication” may be conveyed by indicating a DLRS or UL-RS as spatial relation (for example in 3GPP NR Rel-15/16) or a TCI state (in 3GPP NR Rel-17).

Channel State Information Reference Signals (CSLRS)

For CSI measurement and feedback, CSLRSs may be defined. A CSLRS is transmitted on each antenna port and is used by a WD to measure a downlink channel between each of the transmit antenna ports and each of its receive antenna ports. The transmit antenna ports are also referred to as CSLRS ports. The supported number of antenna ports in NR are { 1,2,4,8,12,16,24,32}. By measuring the received CSLRS, a WD may estimate the channel that the CSLRS is traversing, including the radio propagation channel and antenna gains. The CSLRS for the above purpose is also referred to as Non-Zero Power (NZP) CSLRS.

CSLRS may be configured to be transmitted in certain resource elements (REs) in a slot. FIG. 3 shows an example of CSLRS REs for 12 antenna ports, where one RE per resource block (RB) per port is shown. Due to oscillator imperfections, transmission and reception may not be synchronized in time and/or frequency, which may cause inter- and intra-symbol interference. In NR, a tracking reference signal (TRS) was introduced that may be used by the WD for synchronization.

In NR 3GPP specifications, a TRS may be configured when CSI report setting is not configured or when the higher layer parameter ‘reportQuantity’ in the CSI-ReportConfig information element (IE), associated with all the report settings linked with the CSI-RS resource set containing the TRS(s) is set to ‘none’. This means that CSI reporting based on measurements on TRSs is not supported in NR.

A TRS is configured, for example, via ‘trs-Info’ in the NZP-CSI-RS-Re sourceSet IE of 3GPP Technical Standard (TS) 38.331, which is associated with a CSI-RS resource set for which the WD may assume that the antenna port with the same port index of the configured NZP CSI- RS resources in the said resource set is the same. 3GPP specifications specify a TRS as a special kind of NZP CSI-RS where the corresponding NZP CSI-RS resource set containing the TRS(s) has a higher layer parameter ‘trs-info’ set to true.

TRS is not exactly a CSI-RS, rather it is a resource set consisting of multiple periodic NZP CSI-RS. More specifically, a TRS consists of four one-port, density-3 CSI-RSs located within two consecutive slots. The CSI-RS within the said resource set, may be configured with a periodicity of 10, 20, 40, or 80 ms. Note that the exact set of REs used for the TRS CSI-RS may vary. There is always a four-symbol time-domain separation between the two CSI-RS within a slot. FIG. 4 is an example of a TRS burst of 2 TRS symbols in 2 adjacent slots. It is noted that NR also supports aperiodic TRS.

For LTE, the cell-specific reference signal (CRS) served the same purpose as the TRS. LTE CRS may be used for synchronization, but may also be used for CSI reporting which is not supported for TRS in NR. However, compared to the LTE CRS, the TRS implies much less overhead, only having one antenna port and only being present in two slots every TRS period.

To benefit from the network-controlled repeaters and RISs, there should be proper synchronization between repeaters/RISs and the network node. Particularly, different from, e.g., lAB-nodes or the WDs which receive the signal from a parent node as an end point, network- controlled repeaters and RISs directly forward the received signal with some power amplification and/or phase rotation. Thus, once the network node schedules data transmission for a certain WD, the network-controlled repeater/RIS should synchronously be configured with a proper beam associated with that WD. However, how the network-controlled repeater/RIS node will know exactly when to switch from one symbol to the next, or equivalently from one beam to the next, and also from UL to DL and vice versa, is still an open issue.

SUMMARY

Aspects of the invention are provided in the independent claims, and embodiments thereof are provided in the dependent claims. Some embodiments advantageously provide methods, network nodes and network- controlled repeaters for synchronization methods in repeater-assisted networks.

Some embodiments include a method for proper synchronization between the network- controlled repeater/RIS and the network node. Some methods disclosed herein include determining a proper timing for switching between different beams of the network-controlled repeaters/RISs. This timing may be based on specific configurations and utilize reference signals for, e.g., correlation calculation. This addresses one of the main objectives of the 3GPP Rel-18 study-item on network-controlled repeaters regarding the timing information used to align transmission/reception boundaries of the network-controlled repeaters/RISs.

Some embodiments include methods and apparatuses for switching beams and/or repeater direction (UL/DL) in a network-controlled repeater or RIS. Some embodiments are based on the fact that symbols are time aligned when transmitted by the network node in DL slots and are received time aligned at the network node in UL slots. Hence, it is possible for the repeater, i.e., the network-controlled repeater/RIS, to determine a suitable or ideal beam switching moment for signals that are relayed between the network node and WDs that are associated with the network node via the repeater, based on the repeater’s own timing.

As a consequence of the above, some embodiments may include one or more of the following three aspects:

In a first aspect, a method in the repeater determines DL symbol switching:

1. Determining DL symbol timing at repeater/RIS; and/or

2. Switching beams according to the DL timing of the repeater/RIS.

In a second aspect, a method in the repeater determines UL symbol switching:

1. Determining UL symbol timing at repeater/RIS; and/or

2. Switching beams according to the UL timing of the repeater/RIS.

In a third aspect, a method in the repeater determines switching between DL and UL and vice versa:

1. Determining a switch in direction is occurring;

2. Determining a time gap for changing direction based on DL an UL timing; and/or

3. Switching direction of reception and transmission within a time gap.

In this way, the network-controlled repeater/RIS may be integrated into the network and may serve different WDs with correct timing and beam settings correctly aligned in time. This results in coverage extensions which may provide fairly constant quality-of-service (QoS) for the WDs even in cases with, e.g., blockage. Some embodiments provide a method to determine the appropriate timing for switching between symbols or beams of the network-controlled repeaters/RISs as well as for switching between UL and DL communication. This accomplishes at least one objective of the 3GPP Rel- 18 study -item on network-controlled repeaters, to be started in early 2022. Particularly, some embodiments enable the integration of the network-controlled repeaters/RISs into the network and improves the coverage extension without requiring any additional signaling for doing so. In this way, the network-controlled repeater/RIS helps to efficiently, e.g., bypass the blockages, and avoid performance drop (beam link failure) of the WDs.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present embodiments, and the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein:

FIG. l is a block diagram of one example of a network-controlled repeater;

FIG. 2 is an example of three beam forming procedures;

FIG. 3 is an example of OFDM resource allocation;

FIG. 4 is an example of an allocation of symbols;

FIG. 5 is a schematic diagram of an example network architecture illustrating a communication system connected via an intermediate network to a host computer according to the principles in the present disclosure;

FIG. 6 is a block diagram of a host computer communicating via a network node with a wireless device over an at least partially wireless connection according to some embodiments of the present disclosure;

FIG. 7 is a flowchart illustrating example methods implemented in a communication system including a host computer, a network node and a wireless device for executing a client application at a wireless device according to some embodiments of the present disclosure;

FIG. 8 is a flowchart illustrating example methods implemented in a communication system including a host computer, a network node and a wireless device for receiving user data at a wireless device according to some embodiments of the present disclosure;

FIG. 9 is a flowchart illustrating example methods implemented in a communication system including a host computer, a network node and a wireless device for receiving user data from the wireless device at a host computer according to some embodiments of the present disclosure;

FIG. 10 is a flowchart illustrating example methods implemented in a communication system including a host computer, a network node and a wireless device for receiving user data at a host computer according to some embodiments of the present disclosure;

FIG. 11 is a flowchart of an example process in a network-controlled repeater for synchronization methods in repeater-assisted networks; FIG. 12 is a flowchart of an example process in a network node for according to some embodiments of the present disclosure synchronization methods in repeater-assisted networks;

FIG. 13 is an illustration of a network that includes a network-controlled repeater;

FIG. 14 is an illustration of downlink timing;

FIG. 15 is an illustration of uplink timing;

FIG. 16 is an illustration of downlink and uplink timing;

FIG. 17 is a flowchart of an example process for symbol timing;

FIG. 18 is an illustration of operation of a network-controlled repeater;

FIG. 19 is a flowchart of an example process for timing advance; and

FIG. 20 s a flowchart of an example process determining a direction for switching.

DETAILED DESCRIPTION

Before describing in detail example embodiments, it is noted that the embodiments reside primarily in combinations of apparatus components and processing steps related to synchronization methods in repeater-assisted networks. Accordingly, components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. Like numbers refer to like elements throughout the description.

As used herein, relational terms, such as “first” and “second,” “top” and “bottom,” and the like, may be used solely to distinguish one entity or element from another entity or element without necessarily requiring or implying any physical or logical relationship or order between such entities or elements. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the concepts described herein. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes” and/or “including” when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

In embodiments described herein, the joining term, “in communication with” and the like, may be used to indicate electrical or data communication, which may be accomplished by physical contact, induction, electromagnetic radiation, radio signaling, infrared signaling or optical signaling, for example. One having ordinary skill in the art will appreciate that multiple components may interoperate and modifications and variations are possible of achieving the electrical and data communication.

In some embodiments described herein, the term “coupled,” “connected,” and the like, may be used herein to indicate a connection, although not necessarily directly, and may include wired and/or wireless connections. The term “network node” used herein may be any kind of network node comprised in a radio network which may further comprise any of base station (BS), radio base station, base transceiver station (BTS), base station controller (BSC), radio network controller (RNC), g Node B (gNB), evolved Node B (eNB or eNodeB), Node B, multi-standard radio (MSR) radio node such as MSR BS, multi-cell/multicast coordination entity (MCE), integrated access and backhaul (IAB) node, relay node, donor node controlling relay, radio access point (AP), transmission points, transmission nodes, Remote Radio Unit (RRU) Remote Radio Head (RRH), a core network node (e.g., mobile management entity (MME), self-organizing network (SON) node, a coordinating node, positioning node, MDT node, etc.), an external node (e.g., 3rd party node, a node external to the current network), nodes in distributed antenna system (DAS), a spectrum access system (SAS) node, an element management system (EMS), etc. The network node may also comprise test equipment. The term “radio node” used herein may be used to also denote a wireless device (WD) such as a wireless device (WD) or a radio network node.

In some embodiments, the non-limiting terms wireless device (WD) or a user equipment (UE) are used interchangeably. The WD herein may be any type of wireless device capable of communicating with a network node or another WD over radio signals, such as wireless device (WD). The WD may also be a radio communication device, target device, device to device (D2D) WD, machine type WD or WD capable of machine to machine communication (M2M), low-cost and/or low-complexity WD, a sensor equipped with WD, Tablet, mobile terminals, smart phone, laptop embedded equipped (LEE), laptop mounted equipment (LME), USB dongles, Customer Premises Equipment (CPE), an Internet of Things (loT) device, or a Narrowband loT (NB-IOT) device, etc.

Also, in some embodiments the generic term “radio network node” is used. It may be any kind of a radio network node which may comprise any of base station, radio base station, base transceiver station, base station controller, network controller, RNC, gNB, evolved Node B (eNB), Node B, network node, Multi-cell/multicast Coordination Entity (MCE), IAB node, relay node, access point, radio access point, Remote Radio Unit (RRU) Remote Radio Head (RRH).

Note that although terminology from one particular wireless system, such as, for example, 3GPP LTE and/or New Radio (NR), may be used in this disclosure, this should not be seen as limiting the scope of the disclosure to only the aforementioned system. Other wireless systems, including without limitation Wide Band Code Division Multiple Access (WCDMA), Worldwide Interoperability for Microwave Access (WiMax), Ultra Mobile Broadband (UMB) and Global System for Mobile Communications (GSM), may also benefit from exploiting the ideas covered within this disclosure.

Note further, that functions described herein as being performed by a wireless device or a network node may be distributed over a plurality of wireless devices and/or network nodes. In other words, it is contemplated that the functions of the network node and wireless device described herein are not limited to performance by a single physical device and, in fact, may be distributed among several physical devices. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

As used herein the term “network-controlled repeater” is meant to include amplify-and- forward repeaters that may be configured by a network node, as well as non-amplifying reconfigurable intelligent surfaces (RISs) that may be configured by a network node. For brevity, the term “repeater” is used below in this disclosure for network-controlled repeater, RIS or node with similar functionalities.

Some embodiments provide synchronization methods in repeater-assisted networks. Referring again to the drawing figures, in which like elements are referred to by like reference numerals, there is shown in FIG. 5 a schematic diagram of a communication system 10, according to an embodiment, such as a 3 GPP -type cellular network that may support standards such as LTE and/or NR (5G), which comprises an access network 12, such as a radio access network, and a core network 14. The access network 12 comprises a plurality of network nodes 16a, 16b, 16c (referred to collectively as network nodes 16), such as NBs, eNBs, network nodes or other types of wireless access points, each defining a corresponding coverage area 18a, 18b, 18c (referred to collectively as coverage areas 18). Each network node 16a, 16b, 16c is connectable to the core network 14 over a wired or wireless connection 20. A first wireless device (WD) 22a located in coverage area 18a is configured to wirelessly connect to, or be paged by, the corresponding network node 16a. A second WD 22b in coverage area 18b is wirelessly connectable to the corresponding network node 16b. While a plurality of WDs 22a, 22b (collectively referred to as wireless devices 22) are illustrated in this example, the disclosed embodiments are equally applicable to a situation where a sole WD is in the coverage area or where a sole WD is connecting to the corresponding network node 16. Note that although only two WDs 22 and three network nodes 16 are shown for convenience, the communication system may include many more WDs 22 and network nodes 16.

Also, it is contemplated that a WD 22 may be in simultaneous communication and/or configured to separately communicate with more than one network node 16 and more than one type of network node 16. For example, a WD 22 may have dual connectivity with a network node 16 that supports LTE and the same or a different network node 16 that supports NR. As an example, WD 22 may be in communication with an eNB for LTEZE-UTRAN and a network node for NR/NG-RAN.

The communication system 10 may itself be connected to a host computer 24, which may be embodied in the hardware and/or software of a standalone server, a cloud-implemented server, a distributed server or as processing resources in a server farm. The host computer 24 may be under the ownership or control of a service provider, or may be operated by the service provider or on behalf of the service provider. The connections 26, 28 between the communication system 10 and the host computer 24 may extend directly from the core network 14 to the host computer 24 or may extend via an optional intermediate network 30. The intermediate network 30 may be one of, or a combination of more than one of, a public, private or hosted network. The intermediate network 30, if any, may be a backbone network or the Internet. In some embodiments, the intermediate network 30 may comprise two or more sub-networks (not shown).

The communication system of FIG. 5 as a whole enables connectivity between one of the connected WDs 22a, 22b and the host computer 24. The connectivity may be described as an over- the-top (OTT) connection. The host computer 24 and the connected WDs 22a, 22b are configured to communicate data and/or signaling via the OTT connection, using the access network 12, the core network 14, any intermediate network 30 and possible further infrastructure (not shown) as intermediaries. The OTT connection may be transparent in the sense that at least some of the participating communication devices through which the OTT connection passes are unaware of routing of uplink and downlink communications. For example, a network node 16 may not or need not be informed about the past routing of an incoming downlink communication with data originating from a host computer 24 to be forwarded (e.g., handed over) to a connected WD 22a. Similarly, the network node 16 need not be aware of the future routing of an outgoing uplink communication originating from the WD 22a towards the host computer 24.

A network node 16 is configured to include a repeater configuration unit 32 which is configured to configure a network-controlled repeater 34 with a mapping between beams and symbols and with an indication of slots during which switching beams based on symbol timing is to occur. The network-controlled repeater 34 is configured to determine a symbol timing of at least one of an uplink signal received from the WD and a downlink signal received from the network node; and at least one of: switch between beams and switch between symbols based at least in part on the symbol timing.

Example implementations, in accordance with an embodiment, of the WD 22, network node 16 and host computer 24 discussed in the preceding paragraphs will now be described with reference to FIG. 6. In a communication system 10, a host computer 24 comprises hardware (HW) 38 including a communication interface 40 configured to set up and maintain a wired or wireless connection with an interface of a different communication device of the communication system 10. The host computer 24 further comprises processing circuitry 42, which may have storage and/or processing capabilities. The processing circuitry 42 may include a processor 44 and memory 46. In particular, in addition to or instead of a processor, such as a central processing unit, and memory, the processing circuitry 42 may comprise integrated circuitry for processing and/or control, e.g., one or more processors and/or processor cores and/or FPGAs (Field Programmable Gate Array) and/or ASICs (Application Specific Integrated Circuitry) adapted to execute instructions. The processor 44 may be configured to access (e.g., write to and/or read from) memory 46, which may comprise any kind of volatile and/or nonvolatile memory, e.g., cache and/or buffer memory and/or RAM (Random Access Memory) and/or ROM (Read-Only Memory) and/or optical memory and/or EPROM (Erasable Programmable Read-Only Memory).

Processing circuitry 42 may be configured to control any of the methods and/or processes described herein and/or to cause such methods, and/or processes to be performed, e.g., by host computer 24. Processor 44 corresponds to one or more processors 44 for performing host computer 24 functions described herein. The host computer 24 includes memory 46 that is configured to store data, programmatic software code and/or other information described herein. In some embodiments, the software 48 and/or the host application 50 may include instructions that, when executed by the processor 44 and/or processing circuitry 42, causes the processor 44 and/or processing circuitry 42 to perform the processes described herein with respect to host computer 24. The instructions may be software associated with the host computer 24.

The software 48 may be executable by the processing circuitry 42. The software 48 includes a host application 50. The host application 50 may be operable to provide a service to a remote user, such as a WD 22 connecting via an OTT connection 52 terminating at the WD 22 and the host computer 24. In providing the service to the remote user, the host application 50 may provide user data which is transmitted using the OTT connection 52. The “user data” may be data and information described herein as implementing the described functionality. In one embodiment, the host computer 24 may be configured for providing control and functionality to a service provider and may be operated by the service provider or on behalf of the service provider.

The communication system 10 further includes a network node 16 provided in a communication system 10 and including hardware 58 enabling it to communicate with the host computer 24 and with the WD 22. The hardware 58 may include a communication interface 60 for setting up and maintaining a wired or wireless connection with an interface of a different communication device of the communication system 10, as well as a radio interface 62 for setting up and maintaining at least a wireless connection 64 and 65 with a WD 22 located in a coverage area 18 served by the network node 16, where the wireless connection 64 and 65 is via the network- controlled repeater 34. The radio interface 62 may be formed as or may include, for example, one or more RF transmitters, one or more RF receivers, and/or one or more RF transceivers. The communication interface 60 may be configured to facilitate a connection 66 to the host computer 24. The connection 66 may be direct or it may pass through a core network 14 of the communication system 10 and/or through one or more intermediate networks 30 outside the communication system 10.

In the embodiment shown, the hardware 58 of the network node 16 further includes processing circuitry 68. The processing circuitry 68 may include a processor 70 and a memory 72. In particular, in addition to or instead of a processor, such as a central processing unit, and memory, the processing circuitry 68 may comprise integrated circuitry for processing and/or control, e.g., one or more processors and/or processor cores and/or FPGAs (Field Programmable Gate Array) and/or ASICs (Application Specific Integrated Circuitry) adapted to execute instructions. The processor 70 may be configured to access (e.g., write to and/or read from) the memory 72, which may comprise any kind of volatile and/or nonvolatile memory, e.g., cache and/or buffer memory and/or RAM (Random Access Memory) and/or ROM (Read-Only Memory) and/or optical memory and/or EPROM (Erasable Programmable Read-Only Memory).

Thus, the network node 16 further has software 74 stored internally in, for example, memory 72, or stored in external memory (e.g., database, storage array, network storage device, etc.) accessible by the network node 16 via an external connection. The software 74 may be executable by the processing circuitry 68. The processing circuitry 68 may be configured to control any of the methods and/or processes described herein and/or to cause such methods, and/or processes to be performed, e.g., by network node 16. Processor 70 corresponds to one or more processors 70 for performing network node 16 functions described herein. The memory 72 is configured to store data, programmatic software code and/or other information described herein. In some embodiments, the software 74 may include instructions that, when executed by the processor 70 and/or processing circuitry 68, causes the processor 70 and/or processing circuitry 68 to perform the processes described herein with respect to network node 16. For example, processing circuitry 68 of the network node 16 may include a repeater configuration unit 32 which is configured to configure a network-controlled repeater 34 with a mapping between beams and symbols and with an indication of slots during which switching beams based on symbol timing is to occur.

The communication system 10 further includes the WD 22 already referred to. The WD 22 may have hardware 80 that may include a radio interface 82 configured to communicate with a network node 16, including via a network-controlled repeater 34, serving a coverage area 18 in which the WD 22 is currently located. The radio interface 82 may be formed as or may include, for example, one or more RF transmitters, one or more RF receivers, and/or one or more RF transceivers.

The hardware 80 of the WD 22 further includes processing circuitry 84. The processing circuitry 84 may include a processor 86 and memory 88. In particular, in addition to or instead of a processor, such as a central processing unit, and memory, the processing circuitry 84 may comprise integrated circuitry for processing and/or control, e.g., one or more processors and/or processor cores and/or FPGAs (Field Programmable Gate Array) and/or ASICs (Application Specific Integrated Circuitry) adapted to execute instructions. The processor 86 may be configured to access (e.g., write to and/or read from) memory 88, which may comprise any kind of volatile and/or nonvolatile memory, e.g., cache and/or buffer memory and/or RAM (Random Access Memory) and/or ROM (Read-Only Memory) and/or optical memory and/or EPROM (Erasable Programmable Read-Only Memory).

Thus, the WD 22 may further comprise software 90, which is stored in, for example, memory 88 at the WD 22, or stored in external memory (e.g., database, storage array, network storage device, etc.) accessible by the WD 22. The software 90 may be executable by the processing circuitry 84. The software 90 may include a client application 92. The client application 92 may be operable to provide a service to a human or non-human user via the WD 22, with the support of the host computer 24. In the host computer 24, an executing host application 50 may communicate with the executing client application 92 via the OTT connection 52 terminating at the WD 22 and the host computer 24. In providing the service to the user, the client application 92 may receive request data from the host application 50 and provide user data in response to the request data. The OTT connection 52 may transfer both the request data and the user data. The client application 92 may interact with the user to generate the user data that it provides.

The processing circuitry 84 may be configured to control any of the methods and/or processes described herein and/or to cause such methods, and/or processes to be performed, e.g., by WD 22. The processor 86 corresponds to one or more processors 86 for performing WD 22 functions described herein. The WD 22 includes memory 88 that is configured to store data, programmatic software code and/or other information described herein. In some embodiments, the software 90 and/or the client application 92 may include instructions that, when executed by the processor 86 and/or processing circuitry 84, causes the processor 86 and/or processing circuitry 84 to perform the processes described herein with respect to WD 22.

Still referring to FIG. 6, the network-controlled repeater 34 includes a radio interface 94 and processing circuitry 96. The processing circuitry 96 implements functionality of a switching unit 98, which functionality includes determining a symbol timing of at least one of an uplink signal received from the WD and a downlink signal received from the network node; and at least one of: switching between beams and switching between symbols based at least in part on the symbol timing.

The radio interface 94 may be formed as or may include, for example, one or more RF transmitters, one or more RF receivers, and/or one or more RF transceivers. In some embodiments, the radio interface 94 may include decoding circuitry to decode control information from the network node 16. Based on this decoded information, the switching unit 98 may switch between beams between symbols. The radio interface 94 may also include amplify-and-forward circuitry for relaying one of a downlink beam and an uplink beam.

The processing circuitry 96 may have storage and/or processing capabilities. The processing circuitry 96 may include a processor and memory. In particular, in addition to or instead of a processor, such as a central processing unit, and memory, the processing circuitry 95 may comprise integrated circuitry for processing and/or control, e.g., one or more processors and/or processor cores and/or FPGAs (Field Programmable Gate Array) and/or ASICs (Application Specific Integrated Circuitry) adapted to execute instructions. The processing circuitry may include memory, which may comprise any kind of volatile and/or nonvolatile memory, e.g., cache and/or buffer memory and/or RAM (Random Access Memory) and/or ROM (Read-Only Memory) and/or optical memory and/or EPROM (Erasable Programmable Read-Only Memory).

In some embodiments, the inner workings of the network node 16, WD 22, host computer 24 and network-controlled repeater 34 may be as shown in FIG. 6 and independently, the surrounding network topology may be that of FIG. 5. In FIG. 6, the OTT connection 52 has been drawn abstractly to illustrate the communication between the host computer 24 and the wireless device 22 via the network node 16, without explicit reference to any intermediary devices and the precise routing of messages via these devices. Network infrastructure may determine the routing, which it may be configured to hide from the WD 22 or from the service provider operating the host computer 24, or both. While the OTT connection 52 is active, the network infrastructure may further take decisions by which it dynamically changes the routing (e.g., on the basis of load balancing consideration or reconfiguration of the network).

The wireless connections 64 and 65 between network node 16 and the network-controlled repeater 34 and between the network-controlled repeater 34 and the WD 22 are in accordance with the teachings of the embodiments described throughout this disclosure. One or more of the various embodiments improve the performance of OTT services provided to the WD 22 using the OTT connection 52, in which the wireless connection 64 may form the last segment. More precisely, the teachings of some of these embodiments may improve the data rate, latency, and/or power consumption and thereby provide benefits such as reduced user waiting time, relaxed restriction on file size, better responsiveness, extended battery lifetime, etc.

In some embodiments, a measurement procedure may be provided for the purpose of monitoring data rate, latency and other factors on which the one or more embodiments improve. There may further be an optional network functionality for reconfiguring the OTT connection 52 between the host computer 24 and WD 22, in response to variations in the measurement results. The measurement procedure and/or the network functionality for reconfiguring the OTT connection 52 may be implemented in the software 48 of the host computer 24 or in the software 90 of the WD 22, or both. In embodiments, sensors (not shown) may be deployed in or in association with communication devices through which the OTT connection 52 passes; the sensors may participate in the measurement procedure by supplying values of the monitored quantities exemplified above, or supplying values of other physical quantities from which software 48, 90 may compute or estimate the monitored quantities. The reconfiguring of the OTT connection 52 may include message format, retransmission settings, preferred routing etc.; the reconfiguring need not affect the network node 16, and it may be unknown or imperceptible to the network node 16. Some such procedures and functionalities may be known and practiced in the art. In certain embodiments, measurements may involve proprietary WD signaling facilitating the host computer’s 24 measurements of throughput, propagation times, latency and the like. In some embodiments, the measurements may be implemented in that the software 48, 90 causes messages to be transmitted, in particular empty or ‘dummy’ messages, using the OTT connection 52 while it monitors propagation times, errors, etc.

Thus, in some embodiments, the host computer 24 includes processing circuitry 42 configured to provide user data and a communication interface 40 that is configured to forward the user data to a cellular network for transmission to the WD 22. In some embodiments, the cellular network also includes the network node 16 with a radio interface 62. In some embodiments, the network node 16 is configured to, and/or the network node’s 16 processing circuitry 68 is configured to perform the functions and/or methods described herein for preparing/initiating/maintaining/ supporting/ending a transmission to the WD 22, and/or preparing/terminating/ maintaining/supporting/ending in receipt of a transmission from the WD 22.

In some embodiments, the host computer 24 includes processing circuitry 42 and a communication interface 40 that is configured to a communication interface 40 configured to receive user data originating from a transmission from a WD 22 to a network node 16. In some embodiments, the WD 22 is configured to, and/or comprises a radio interface 82 and/or processing circuitry 84 configured to perform the functions and/or methods described herein for preparing/initiating/maintaining/ supporting/ending a transmission to the network node 16, and/or preparing/ terminating/maintaining/supporting/ending in receipt of a transmission from the network node 16.

Although FIGS. 5 and 6 show various “units” such as repeater configuration unit 32, and switching unit 98 as being within a respective processor, it is contemplated that these units may be implemented such that a portion of the unit is stored in a corresponding memory within the processing circuitry. In other words, the units may be implemented in hardware or in a combination of hardware and software within the processing circuitry.

FIG. 7 is a flowchart illustrating an example method implemented in a communication system, such as, for example, the communication system of FIGS. 5 and 6, in accordance with one embodiment. The communication system may include a host computer 24, a network node 16 and a WD 22, which may be those described with reference to FIG. 6. In a first step of the method, the host computer 24 provides user data (Block SI 00). In an optional substep of the first step, the host computer 24 provides the user data by executing a host application, such as, for example, the host application 50 (Block SI 02). In a second step, the host computer 24 initiates a transmission carrying the user data to the WD 22 (Block SI 04). In an optional third step, the network node 16 transmits to the WD 22 the user data which was carried in the transmission that the host computer 24 initiated, in accordance with the teachings of the embodiments described throughout this disclosure (Block SI 06). In an optional fourth step, the WD 22 executes a client application, such as, for example, the client application 92, associated with the host application 50 executed by the host computer 24 (Block SI 08).

FIG. 8 is a flowchart illustrating an example method implemented in a communication system, such as, for example, the communication system of FIG. 5, in accordance with one embodiment. The communication system may include a host computer 24, a network node 16 and a WD 22, which may be those described with reference to FIGS. 5 and 6. In a first step of the method, the host computer 24 provides user data (Block SI 10). In an optional substep (not shown) the host computer 24 provides the user data by executing a host application, such as, for example, the host application 50. In a second step, the host computer 24 initiates a transmission carrying the user data to the WD 22 (Block SI 12). The transmission may pass via the network node 16, in accordance with the teachings of the embodiments described throughout this disclosure. In an optional third step, the WD 22 receives the user data carried in the transmission (Block SI 14).

FIG. 9 is a flowchart illustrating an example method implemented in a communication system, such as, for example, the communication system of FIG. 5, in accordance with one embodiment. The communication system may include a host computer 24, a network node 16 and a WD 22, which may be those described with reference to FIGS. 5 and 6. In an optional first step of the method, the WD 22 receives input data provided by the host computer 24 (Block SI 16). In an optional substep of the first step, the WD 22 executes the client application 92, which provides the user data in reaction to the received input data provided by the host computer 24 (Block SI 18). Additionally or alternatively, in an optional second step, the WD 22 provides user data (Block S120). In an optional substep of the second step, the WD provides the user data by executing a client application, such as, for example, client application 92 (Block S122). In providing the user data, the executed client application 92 may further consider user input received from the user. Regardless of the specific manner in which the user data was provided, the WD 22 may initiate, in an optional third substep, transmission of the user data to the host computer 24 (Block S124). In a fourth step of the method, the host computer 24 receives the user data transmitted from the WD 22, in accordance with the teachings of the embodiments described throughout this disclosure (Block S126).

FIG. 10 is a flowchart illustrating an example method implemented in a communication system, such as, for example, the communication system of FIG. 5, in accordance with one embodiment. The communication system may include a host computer 24, a network node 16 and a WD 22, which may be those described with reference to FIGS. 5 and 6. In an optional first step of the method, in accordance with the teachings of the embodiments described throughout this disclosure, the network node 16 receives user data from the WD 22 (Block SI 28). In an optional second step, the network node 16 initiates transmission of the received user data to the host computer 24 (Block SI 30). In a third step, the host computer 24 receives the user data carried in the transmission initiated by the network node 16 (Block SI 32).

FIG. 11 is a flowchart of an example process in a network-controlled repeater 34 for synchronization methods in repeater-assisted networks. One or more blocks described herein may be performed by one or more elements of network-controlled repeater 34 such as by one or more of processing circuitry 96 (including the switching unit 32), and/or radio interface 94. Network- controlled repeater 34 such as via processing circuitry 96 and/or radio interface 94 is configured to determine a symbol timing of at least one of an uplink signal received from the WD and a downlink signal received from the network node (Block SI 34). The process also includes at least one of: switch between beams and switch between symbols based at least in part on the symbol timing (Block S136).

In some embodiments, the process also includes determining a time gap for one of switching between beams and switching between symbols based on downlink symbol timing and uplink signal timing. In some embodiments, the method also includes receiving from the network node a configuration indicating which beam to configure for each symbol. In some embodiments, a downlink symbol timing is determined by correlating a reference signal from the network node with a set of at least one known sequence. In some embodiments, the switching is timed to occur between symbols based on the determined symbol timing. In some embodiments, the method also includes providing a capability report to the network node, the capability report including at least one of a beam switching speed, and a control word decoding speed.

FIG. 12 is a flowchart of an example process in a network node 16 according to some embodiments of the present disclosure for synchronization methods in repeater-assisted networks. One or more blocks described herein may be performed by one or more elements of network node 16 such as by one or more of processing circuitry 68 (including the repeater configuration unit 32), processor 70, radio interface 62 and/or communication interface 60. Network node 16 such as via processing circuitry 68 and/or processor 70 and/or radio interface 62 is configured to configure the repeater with a mapping between beams and symbols (Block S138); and configure the repeater with an indication of slots during which switching between beams based on symbol timing is to occur at the repeater (Block S140)

In some embodiments, the process also includes configuring the repeater with a delay between an end of a downlink transmission from the network node to the repeater and an initiation of an uplink transmission from the repeater to the network node. In some embodiments, the delay includes a margin of time between edges of a switching interval to account for timing misalignment between the repeater and the network node. In some embodiments, the method also includes configuring the repeater with a timing advance for determining when to switch between beams.

Having described the general process flow of arrangements of the disclosure and having provided examples of hardware and software arrangements for implementing the processes and functions of the disclosure, the sections below provide details and examples of arrangements for synchronization methods in repeater-assisted networks.

The system model considers a source node (e.g., a network node 16) communicating with one or more destination nodes (e.g., WDs 22) in wireless communication links that are relayed by a repeater node (or network-controlled repeater, which may include an intelligent surface) 34, as shown in the example diagram of FIG. 13.

FIG. 13 presents an example of the considered network where a source node, e.g., a network node 16, TRP, communicates with one or more destination nodes, e.g., WDs 22, using an intermediate repeater 34, e.g., network-controlled repeater or intelligent surface. One objective may include determining a DL or UL symbol switching timing, as illustrated in FIGS. 14 and 15, respectively, and also the proper timing for switching between the UL to DL transmission and vice versa (see FIG. 16). That is, the repeater node 34 preferably knows exactly when to switch from one symbol to the next, or equivalently from one beam to the next, since the beams are potentially aligned with symbols. It is assumed that the repeater node 34 is already connected to the network, and that a suitable network node 16 beam and repeater beam pair for the network node-repeater link has already been determined.

FIGS. 14 and 15 are timing diagrams showing examples of the propagation delay between the different nodes in FIG. 13, for the DL and UL, respectively, where the repeater 34 is configured to relay the first symbol SDL,I to Device 1 (WD 22a) and the second symbol, SDL,2 to Device 2 (WD 22b). As is evident in FIG.16, for the DL, Device 1 (WD 22a) and Device 2 (WD 22b) (and the repeater 34 itself) share the same service link and thereby propagation path from the network node 16 to the repeater 34, after which the individual access links and propagation paths results in different timing (and beamforming) between Device 1 and Device 2. Hence, the ideal switching in the repeater 34, in order to service SDL,I to Device 1 (Wd 22a) and SDL,2 to Device 2 (WD 22b) is (symbol -)aligned with the reception timing of the symbols at the repeater 34.

Correspondingly, for the UL, Device 1 (WD 22a) and Device 2 (WD 22b) (and the repeater 34) are configured such that their respective signals should be received simultaneously at the network node. Also here, Device 1 (WD 22a) and Device 2 (WD 22b) share service link, and thereby propagation path between repeater 34 and network node 16, and the only difference is in the respective access links between respective device (WD 22) and the repeater 34. For that reason, as an example setup, Device 2 is configured by timing advance (TA) to start transmitting its symbols ahead of Device 1 (WD 22a) due to Device 2’s (WD 22b) (assumed) longer propagation path taccess,2 compared to Device 1 S taccess, 1 -

Additionally, FIG. 16 presents the gap between DL and UL operation, that is configured for each node that is associated with the network node 16 in order for their respective UL transmissions to be simultaneously received by the network node 16. As is visible in FIG. 16, for the case where Device 1 (WD 22a) and Device 2 (WD 22b) are relayed via the repeater 34, the duration between the reception of a DL transmission and the initialization of an UL transmission, HA is larger for the repeater compared to both Device 1 (WD 22a) and Device 2 (WD 22b). Hence, any time during this gap, the repeater 34 may change transmission direction from DL to UL, in order to properly service an UL transmission from Device 1 (WD 22a) and/or Device 2 (WD 22b) to the network node 16.

To integrate the repeater node into the network and serve the WDs through the repeater, the exact timing to switch between different beams of the repeater as well as the proper timing for switching between DL and UL and vice versa should be known. This is particularly different from WDs/IAB nodes, because in the network-controlled repeaters, the received signal is directly forwarded to the next nodes with, e.g., some power amplification (in amplify-and- forward repeaters) and/or phase rotation. It may be expected that a fast connection is required between the network node and the repeater, since the control signaling from network node used to control the repeater will likely depend on the scheduling decisions of the network node. For example, in case the network node schedules data transmission for a certain WD, the network- controlled repeaters/RISs should preferably be configured with a beam, communication direction and power allocation associated with that WD.

Some embodiments include methods in a wireless repeater/RIS for switching between beams and/or transmission directions (DL/UL) for relaying a signal from a network node to a device or vice versa. This comprises three aspects including the determination of DL symbol switching timing, UL symbol switching timing and DL/UL switching timing as follows.

DL beam switching aspect

In some embodiments, a method in the repeater 34 for determining DL symbol/beam switching is provided. The terms symbols and beams may be used interchangeably since a symbol is transmitted in a beam. Hence, a beam change may not take place unless in-between symbols or in immediate proximity to the symbol bounds. This synchronization may be achieved based on the steps of FIG. 17.

Referring to FIG. 17, in an optional step (100), the repeater 34 provides a capability report to the network and thereby the network node 16, including information about beam and switching capabilities. The capability report may include a of available beams, how quickly the repeater 34 may switch the beams, how quickly the repeater 34 may decode control information related to beam settings.

In yet another optional step (110), the repeater 34 receives a configuration related to which beams the repeater should configure in which symbols. Such configuration may take place with radio resource control (RRC), medium access control (MAC) control element (CE) and/or downlink control information (DCI) signaling. Furthermore, the configuration may be explicit, or implicit, e.g., related to a WD 22 in which case the repeater has the information about the beam-to-WD mapping.

In a first step (120), the repeater 34 may determine its DL symbol timing using the control link. This step is similar to how WDs 22 perform symbol timing by using SSBs or parts of SSBs and correlating with known sequences of SSB or parts of SSB. Note that averaging over more SSBs will improve synchronization further. How many SSBs to use will be a balance between the synchronization accuracy and overhead. The more SSBs being used, the better synchronization at the repeater 34, at the cost of more overhead. Note that while the setup for the cases with correlation calculation and SSBs are presented, the repeater 34 may also determine synchronization from other signals, and by means other than correlation. For instance, other synchronization reference signals such as TRS, CSLRS, DMRS, primary synchronization signals (PSS) or secondary synchronization signals (SSS) of a synchronization signal block (SSB) may be utilized. The repeater node 34 may be expected to know the delay of such a correlation in relation to when the signal was received. Hence, from knowing the maximum of the correlation with the SSB (or TRS, CSLRS, DMRS, PSS or SSS of SSB), and the delay of the correlation operation, the absolute synchronization time, i.e., the border between two symbols, may be determined. Note that the network node 16 typically sends out multiple different SSBs in different “SSB beams” in FR2 deployments, where the different SSBs are sent out at different times. Hence, the repeater 34 must determine the timing on a specific (pre-determined) SSB, in order to attain a relevant (non-ambiguous) symbol timing. In one embodiment, one of the SSBs already specified in NR (for example the SSB with SSB index 1) may be used to determine the symbol timing of the repeater 34. In some embodiments, the determined symbol timing indicates a reference system frame number (SFN), a reference slot number and/or a reference symbol number within that frame/slot.

In a further step (130), the repeater 34 changes its DL transmit beamforming of the access link from the beam that was configured in the first symbol to the beam that is configured in the second symbol at the instance when the repeater itself finds itself in-between two symbols to forward. In some embodiments, there is an adjustment offset, adjusting for known circuitry delay or computation delay etc., in the repeater 34.

In one embodiment, there is an adjustment offset based on which beam pair link (BPL) is used between the network node 16 and repeater node 34. There might exist several different beam pair links between the network node 16 and the repeater 34, for example there might be one primary line-of-sight (LOS) BPL, and one or more back-up non-LOS (NLOS) BPLs. The NLOS BPLs may be used for example if the LOS BPL gets blocked, or to handle co-scheduling of WDs. It may occur that a first WD 22 should be co-scheduled (e.g., by frequency division multiplexing) with a second WD 22 when the second WD 22 is served through the repeater node, and where the first WD 22 only may be served by a network node beam associated with one of the NLOS BPLs to the repeater node 34. Therefore, the network node 16 may be configured to quickly switch between the different BPLs between the network node and repeater node.

One example of how multiple different BPLs between a network node 16 and a repeater node 34 might look is illustrated in FIG. 18 where BPL1 is the LOS BPL, and BPL2 and BPL3 are NLOS BPLs. Since the different BPLs have different path lengths, the delay of the different BPLs will differ, which means that depending on which BPL is used between the network node 16 and the repeater node 34, the timing of the DL signals received by the repeater node 34 to forward to serving WDs 22 will differ. In order to optimize the beam switching timing of the access link of the repeater node 34, the repeater node 34 may adapt the beam switch timing based on the estimated synchronization associated with the applied BPL.

In one embodiment, the repeater node 34 pre-estimates and stores the delay differences between candidate BPLs, and when the network node 16 switches the BPL between the network node 16 and the repeater 34, the repeater 34 automatically adjusts the beam switch timing of the access link of the repeater 34 to compensate for the changed delay between the old and the new BPL. The repeater 34 may for example use SSB, TRS, DMRS or CSLRS associated with a certain BPL to pre-determine the estimated delays associated with each BPL (for example, a BPL might be associated with a certain TCI state which directly or indirectly is associated with one or more of an SSB, TRS, DMRS an CSLRS). In one embodiment, the switching configuration has a periodic (or semi-static) switching behavior, i.e., where the repeater in a time repetitive way switches between different modes of operation (e.g., different repeater beams). In one embodiment, the switching configuration has an aperiodic switching behavior, i.e., where the repeater switching between different modes of operation only happen once.

Note that the steps of FIG. 17 are only residual adjustment steps. Hence, before step (100), the repeater 34 will have synchronized towards the network node 16 and obtained a proper timing advance from the network in order to transmit capabilities and receive configurations from the network, in some embodiments.

UL beam switching aspect

In some embodiments, methods in the repeater 34 for determining the UL symbol switching are provided. In some embodiments, one or more of the following steps may be performed as shown in FIG. 19.

In an optional step (200), the repeater 34 provides a capability report to the network and to the network node 16, including information about beam and switching capabilities. As for step (100), the capability report may include how many beams are available, how quickly the repeater 34 may switch beams, how quickly the repeater 34 may decode the beam-setting-related control information.

In yet another optional step (210), the repeater 34 receives a configuration related to which beams the repeater 34 should configure in which symbols.

In step (220), the repeater’s 34 timing advance is set or updated based on signaling by the network node 16 similar to the way a WD’s timing advance is set.

In step (230), the repeater 34 changes its UL receive beamforming of the access link from the beam that was configured in the first symbol to the beam that is configured in the second symbol at the instance when the repeater 34 itself finds itself in-between the two symbols to forward. In some embodiments, there is an adjustment offset, adjusting for known circuitry delay or computation delay, etc., in the repeater 34. There may be additional adjustment offsets related to different path lengths of different BPLs applied between the network node 16 and repeater node 34.

Also here, the steps presented may only be residual adjustment steps. Hence, before (200), the repeater 34 may have synchronized towards the network node 16 and obtained a proper timing advance from the network in order to transmit capabilities and receive configurations from the network.

Transmission direction aspect

According to another aspect, methods in the repeater 34 for determining switching between DL and UL and vice versa, are provided. In step (300), the repeater 34 synchronizes and connects to the network and receives UL/DL/F configuration as well as configuration about which slots are special slots, in which a change of transmission direction should take place. This configuration may be based on RRC, MAC-CE and/or DCI signaling.

In step (310), the repeater 34 receives a timing message, indicating the delay between the end of a DL transmission and the initiation of an UL transmission. In step (320), the repeater 34 determines the instant of the direction switch of both access and service links, i.e., the circuitry enabling said links, as somewhere in-between the end of the DL transmission (symbol) and the start of the succeeding UL transmission (symbol). There may furthermore be a margin to the edges of the allowed switch interval allowing for imperfect timing alignment between the repeater 34 and associated devices at the network node 16. Subsequently, the repeater 34 configures itself to make the corresponding change in direction, e.g., by enabling different Tx and Rx circuitry and/or antenna elements/modules. This is possible at least because the DL timing at the repeater 34 is the same regardless of whether the repeater 34 or any of its associated devices are addressed. Correspondingly, with some small timing error, the UL timing is also the same at the repeater 34 regardless of the repeater 34 or any of its associated devices, e.g., WDs 22, addressing the network node 16. Consequently, based on the understanding that the propagation path between the repeater 34 and the network node 16 is the same for both repeater 34 and served devices, and both DL and UL transmissions are synchronized at the network node 16, the repeater 34 may use this information to determine an interval within which switching between UL and DL is acceptable, in-between the end of the UL transmission (symbol) and the start of a subsequent DL transmission (symbol).

In this way, some embodiments provide an accurate synchronization method to switch between different beams/symbols/directions in network-controlled repeater 34, which may include RISs. In some embodiments, the integration of the network-controlled repeaters 34 into the network improves coverage extension without requiring any additional signaling for doing so. This addresses at least one objective of the 3GPP Rel-18 study-item on network-controlled repeaters 34 regarding the timing information to align transmission/reception boundaries of the network-controlled repeaters/RISs which, in turn, leads to coverage extension and fairly constant QoS for the WDs.

As will be appreciated by one of skill in the art, the concepts described herein may be embodied as a method, data processing system, computer program product and/or computer storage media storing an executable computer program. Accordingly, the concepts described herein may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects all generally referred to herein as a “circuit” or “module.” Any process, step, action and/or functionality described herein may be performed by, and/or associated to, a corresponding module, which may be implemented in software and/or firmware and/or hardware. Furthermore, the disclosure may take the form of a computer program product on a tangible computer usable storage medium having computer program code embodied in the medium that may be executed by a computer. Any suitable tangible computer readable medium may be utilized including hard disks, CD-ROMs, electronic storage devices, optical storage devices, or magnetic storage devices.

Some embodiments are described herein with reference to flowchart illustrations and/or block diagrams of methods, systems and computer program products. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, may be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer (to thereby create a special purpose computer), special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks.

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

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

It is to be understood that the functions/acts noted in the blocks may occur out of the order noted in the operational illustrations. For example, two blocks shown in succession may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending upon the functionality/acts involved. Although some of the diagrams include arrows on communication paths to show a primary direction of communication, it is to be understood that communication may occur in the opposite direction to the depicted arrows.

Computer program code for carrying out operations of the concepts described herein may be written in an object oriented programming language such as Python, Java® or C++. However, the computer program code for carrying out operations of the disclosure may also be written in conventional procedural programming languages, such as the "C" programming language. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer. In the latter scenario, the remote computer may be connected to the user's computer through a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider).

Many different embodiments have been disclosed herein, in connection with the above description and the drawings. It will be understood that it would be unduly repetitious and obfuscating to literally describe and illustrate every combination and subcombination of these embodiments. Accordingly, all embodiments may be combined in any way and/or combination, and the present specification, including the drawings, shall be construed to constitute a complete written description of all combinations and subcombinations of the embodiments described herein, and of the manner and process of making and using them, and shall support claims to any such combination or subcombination.

Abbreviations that may be used in the preceding description include:

BPL Beam pair link

BS Base station

IRS Intelligent reflecting surface

RF Radio frequency

RIS Reconfigurable intelligent surface

Rx Receiver

Tx Transmitter

WD Wireless device

It will be appreciated by persons skilled in the art that the embodiments described herein are not limited to what has been particularly shown and described herein above. In addition, unless mention was made above to the contrary, it should be noted that all of the accompanying drawings are not to scale. A variety of modifications and variations are possible in light of the above teachings.

Example embodiments:

Embodiment Al. A network-controlled repeater configured to relay signals between a wireless device (WD) and a network node, the repeater configured to, and/or comprising a radio interface and/or comprising processing circuitry configured to: determine a symbol timing of at least one of an uplink signal received from the WD and a downlink signal received from the network node; and at least one of: switch between beams and switch between symbols based at least in part on the symbol timing.

Embodiment A2. The repeater of Embodiment Al, wherein the repeater, radio interface and/or processing circuitry are further configured to determine a time gap for one of switching between beams and switching between symbols based on downlink symbol timing and uplink signal timing. Embodiment A3. The repeater of any of Embodiments Al and A2, wherein the repeater, radio interface, and/or processing circuitry are further configured to receive from the network node a configuration indicating which beam to configure for each symbol.

Embodiment A4. The repeater of any of Embodiments A1-A3, wherein a downlink symbol timing is determined by correlating a reference signal from the network node with a set of at least one known sequence.

Embodiment A5. The repeater of any of Embodiments A1-A4, wherein the switching is timed to occur between symbols based on the determined symbol timing.

Embodiment A6. The repeater of any of Embodiments A1-A5, wherein the repeater, radio interface and/or processing circuitry are further configured to provide a capability report to the network node, the capability report including at least one of a beam switching speed, and a control word decoding speed.

Embodiment Bl. A method implemented in a network-controlled repeater configured to communicate with a network node and a wireless device, WD, the method comprising: determining a symbol timing of at least one of an uplink signal received from the WD and a downlink signal received from the network node; and at least one of: switching between beams and switching between symbols based at least in part on the symbol timing.

Embodiment B2. The method of Embodiment Bl, further comprising determining a time gap for one of switching between beams and switching between symbols based on downlink symbol timing and uplink signal timing.

Embodiment B3. The method of any of Embodiments Bl and B2, further comprising receiving from the network node a configuration indicating which beam to configure for each symbol.

Embodiment B4. The method of any of Embodiments B1-B3, wherein a downlink symbol timing is determined by correlating a reference signal from the network node with a set of at least one known sequence.

Embodiment B5. The method of any of Embodiments B1-B4, wherein the switching is timed to occur between symbols based on the determined symbol timing.

Embodiment B6. The method of any of Embodiments B1-B5, further comprising providing a capability report to the network node, the capability report including at least one of a beam switching speed, and a control word decoding speed.

Embodiment Cl . A network node configured to communicate with a wireless device, WD, via a network-controlled repeater, configured to, and/or comprising a radio interface and/or processing circuitry configured to configure the repeater with a mapping between beams and symbols; and configure the repeater with an indication of slots during which switching between beams based on symbol timing is to occur at the repeater. Embodiment C2. The WD of Embodiment Cl, wherein the network node, radio interface and/or processing circuitry are further configured to configure the repeater with a delay between an end of a downlink transmission from the network node to the repeater and an initiation of an uplink transmission from the repeater to the network node.

Embodiment C3. The WD of Embodiment C2, wherein the delay includes a margin of time between edges of a switching interval to account for timing misalignment between the repeater and the network node.

Embodiment C4. The WD of any of Embodiments C1-C3, wherein the network node, radio interface and/or processing circuitry are further configured to configure the repeater with a timing advance for determining when to switch between beams.

Embodiment DI. A method implemented in a network node configured to communicate with a wireless device, WD, via a network-controlled repeater, the method comprising: configuring the repeater with a mapping between beams and symbols; and configuring the repeater with an indication of slots during which switching between beams based on symbol timing is to occur at the repeater.

Embodiment D2. The method of Embodiment DI, further comprising configuring the repeater with a delay between an end of a downlink transmission from the network node to the repeater and an initiation of an uplink transmission from the repeater to the network node.

Embodiment D3. The method of Embodiment D2, wherein the delay includes a margin of time between edges of a switching interval to account for timing misalignment between the repeater and the network node.

Embodiment D4. The method of any of Embodiments DI -D3, further comprising configuring the repeater with a timing advance for determining when to switch between beams.