Establishing device-to-device (D2D) communications using local-area repeaters

Abstract

A method for establishing a device-to-device (D2D) communication via a repeater node is provided. The method comprises transmitting, to the repeater node, first configuration information which indicates a first configuration for configuring a first side of the repeater node to forward at least first reference signal and second configuration information which indicates a second configuration for configuring a second side of the repeater node to forward at least second reference signal. The method further comprises, after transmitting at least first and second reference signals to the repeater node, receiving a first report message from a first device and a second report message from a second device. The method comprises determining, for the D2D communication, an operation mode and / or a configuration of the repeater node; and transmitting, to the repeater node, repeater configuration information indicating the determined operation mode and / or the determined configuration of the repeater node.

Description

ESTABLISHING DEVICE-TO-DEVICE (D2D) COMMUNICATIONS USING LOCAL-AREA REPEATERSTECHNICAL FIELD

[0001] This disclosure relates to establishing device-to-device (D2D) communications using local-area (LA) repeaters.BACKGROUND

[0002] Network-Controlled Repeater

[0003] As described in the 3rd Generation Partnership Project (3GPP) Technical Reports (TR) § 38.867, a network-controlled repeater (NCR) is an enhancement over conventional radio frequency (RF) repeaters.

[0004] RF repeaters simply amplify-and-forward any signal that they receive. They have been used in a wide range of deployments in 2G, 3G, and 4G to supplement the coverage provided by regular full-stack cells. In 3GPP Release 17 (Rel-17), RAN4 specified RF and electromagnetic compatibility (EMC) requirements for such RF repeaters for new radio (NR) / 5G targeting both Frequency Range 1 (FR1) and Frequency Range 2 (FR2).

[0005] While an RF repeater presents a cost-effective means of extending network coverage, it has its limitations. For example, an RF repeater simply performs an amplify-and-forward (AF) operation without being able to take into account various factors that could improve network performance. Examples of such factors include information on semi-static and / or dynamic downlink / uplink configuration, adaptive transmitter / receiver spatial beamforming, ON-OFF status, and so on.

[0006] An NCR can be seen as a conventional RF repeater with the capability to receive and process side control information from the network. The side control information allows an NCR to perform the amplify-and-forward operation in a more efficient manner. Potential benefits of using an NCR over a conventional RF repeater include transmissions and receptions with better spatial directivity, mitigation of unnecessary noise amplification, and simplified network integration. Particularly, the main feature of NCR is beamforming capability which is of interest specially in FR2.

[0007] Using NCRs is an alternative way of improving network coverage when the deployment of full-stack cells is not an option, e.g., because of unavailability of backhaul or because the deployment of full-stack cells is not economically viable. In general, an NCR can be considered as a network-controlled “beam bended relative to a base station (e.g., gNB). In this way, an NCR is logically part of the gNB for all management purposes. In other words, it can be assumed that the NCR is deployed and under the control of the network operator.

[0008] In RAN4, different types of NCRs have been defined; At the UE-side of NCR, wide-area (WA), medium range (MR) and local-area (LA) have been defined. At the gNB-side, on the other hand, WA and LA types of links have been defined. These types of links' properties can be declared independently. The main differences between the WA and LA links are on the level of network planning and transmit power. WA links benefit from high transmit power / amplification gain and are well-planned where, for instance, the gNB-side of the node is located on the rooftop or similar, to achieve LOS over a longer distance to a serving gNB. For the LA type, on the other hand, the node may be mounted at low heights, e.g., lamppost, etc., and does not have higher power than a typical UE.

[0009] Intelligent Reflecting Surface (IRS)

[0010] IRS, also known as reconfigurable intelligent surface (RIS), is an emerging technology that is capable of intelligently manipulating the propagation of electro -magnetic waves. An IRS is composed of a 2- dimensional array of reflecting elements, where each element acts as a passive reconfigurable scatterer, i.e., a piece of manufactured material, which can be programmed to change an impinging electro -magnetic wave in a customizable way.

[0011] Such elements are usually low-cost passive surfaces that do not require dedicated power sources, and the radio waves impinged upon them can be forwarded without the need of employing power amplifier or RF chain. Moreover, IRS can potentially work in full duplex mode without significant self-interference or increased noise level and requires only low-rate control link or backhaul connections.

[0012] IRS can be flexibly deployed due to its low weight and low power consumption. Specially, IRS is of interest in stationary or low-mobility networks, in which the transmission parameters can be well planned . Via IRS- assisted communication, blockages / tree foliage can be bypassed.

[0013] There are still ambiguities about the detailed differences between NCRs and IRSs (see reference [1] cited below for a conceptual comparison of NCRs and IRSs). A simple explanation of these ambiguities is that an IRS is an NCR with negative amplification.

[0014] Despite these ambiguities, in general, IRS is expected to be a simpler and cheaper node with less focused beamforming capability / accuracy and without active amplification. That is, IRS may be capable of performing signal reflection via adapting a phase matrix while NCR is capable of performing advanced beamforming with power amplification.

[0015] In this disclosure, a repeater refers to an NCR, an IRS, or a node capable of performing functions similar to the functions of the NCR and / or the IRS.

[0016] D2D Communication

[0017] D2D or sidelink communication is a communication scheme that allows a direct communication between two UEs in a system without traversing a base station (“BS”) as in regular cellular networks. However, setting up a D2D communication is usually assisted by a BS. For example, a BS is responsible for defining, amongother various parameters, the frequency resources that the D2D UEs can use to communicate each other without causing interference on other UEs.

[0018] One of the advantages of D2D communications is a higher spectral efficiency . The higher spectral efficiency is possible in D2D communications because the frequency resources used by the D2D UEs can also be reused by the BS to communicate with other UEs. Such reusing of the frequency resources does not interfere with the D2D communications and the BS's communications with other UEs.

[0019] Another advantage of D2D communications is lower latency. Lower latency is possible in D2D communications because, in D2D communications, a delay caused by forwarding messages through the BS is eliminated.

[0020] This is an important aspect of D2D communications explored in the context of vehicular communications. Vehicle-to-everything (V2X) is a particular use case of D2D communications in which a vehicle (i.e., a UE) can communicate, for example, with another vehicle, a pedestrian , and / or a traffic infrastructure.

[0021] D2D UEs may be paired based on the quality of a channel between the two UEs. For example, state-of-the-art solutions usually employ sidelink control information to identify UEs with good channel quality between them in order to pair them for a D2D communication.SUMMARY

[0022] Certain challenges presently exist in the existing D2D communications. For example, in some scenarios, the pair of devices involved in a D2D communication may experience low channel quality in communication with each other. Such low channel quality in communication may be due to presence of an entity (e.g., building (s)) that is in the direct line of sight between the devices. In such scenarios, repeater -assisted D2D communication may be used.

[0023] Accordingly, in one aspect of some embodiments of this disclosure, there is provided a method for establishing a device-to-device, D2D, communication via a repeater node. The method is performed by a network node. The method comprises transmitting, to the repeater node, first configuration information which indicates a first configuration for configuring a first side of the repeater node to forward at least first reference signal that the repeater node receives from the network node. The method further comprises transmitting, to the repeater node, second configuration information which indicates a second configuration for configuring a second side of the repeater node to forward at least second reference signal that the repeater node receives from the network node. The method further comprises, after transmitting the first configuration information to the repeater node, transmitting said at least first reference signal to the repeater node; and after transmitting the second configuration information to the repeater node, transmitting said at least second reference signal to the repeater node. The method further comprises, after transmitting said at least first and second reference signals to the repeater node, receiving a first report message from a first device, wherein the first report message indicates a measurement result of one of said at least first and secondreference signals received at the first device via the repeater node; and after transmitting said at least first and second reference signals to the repeater node, receiving a second report message from a second device, wherein the second report message indicates a measurement result of one of said at least first and second reference signals received at the second device via the repeater node. The method further comprises based on the measurement results, determining, for the D2D communication, an operation mode and / or a configuration of the repeater node; and transmitting, to the repeater node, repeater configuration information indicating the determined operation mode and / or the determined configuration of the repeater node.

[0024] In another aspect, there is provided a method for establishing a device-to-device, D2D, communication via a repeater node. The method is performed by the repeater node. The method comprises receiving, from a network node, first configuration information which indicates a first configuration for configuring a first side of the repeater node to forward at least first reference signal that the repeater node receives from the network node; and receiving, from the network node, second configuration information which indicates a second configuration for configuring a second side of the repeater node to forward at least second reference signal that the repeater node receives from the network node. The method further comprises after receiving the first configuration information from the network node, receiving said at least first reference signal from the network node; after receiving the second configuration information from the network node, receiving said at least second reference signal from the network node; and forwarding or reflecting said at least first reference signal from the first side of the repeater node. The method further comprises forwarding or reflecting said at least second reference signal from the second side of the repeater node; and receiving, from the network node, repeater configuration information indicating an operation mode and / or a configuration of the repeater node for the D2D communication.

[0025] In a different aspect, there is provided a computer program comprising instructions which when executed by processing circuitry cause the processing circuitry to perform the the method of any one of the above embodiments.

[0026] In a different aspect, there is provided a carrier containing the computer program of the above embodiment, wherein the carrier is one of an electronic signal, an optical signal, a radio signal, and a computer readable storage medium.

[0027] In a different aspect, there is provided a network node for establishing a device-to-device, D2D, communication via a repeater node. The network node is configured to: transmit, to the repeater node, first configuration information which indicates a first configuration for configuring a first side of the repeater node to forward at least first reference signal that the repeater node receives from the network node. The network node is further configured to transmit, to the repeater node, second configuration information which indicates a second configuration for configuring a second side of the repeater node to forward at least second reference signal that the repeater node receives from the network node; after transmitting the first configuration information to the repeater node, transmit saidat least first reference signal to the repeater node; and after transmitting the second configuration information to the repeater node, transmit said at least second reference signal to the repeater node. The network node is further configured to, after transmitting said at least first and second reference signals to the repeater node, receive a first report message from a first device, wherein the first report message indicates a measurement result of one of said at least first and second reference signals received at the first device via the repeater node. The network node is further configured to, after transmitting said at least first and second reference signals to the repeater node, receive a second report message from a second device, wherein the second report message indicates a measurement result of one of said at least first and second reference signals received at the second device via the repeater node; based on the measurement results, determine, for the D2D communication, an operation mode and / or a configuration of the repeater node; and transmit, to the repeater node, repeater configuration information indicating the determined operation mode and / or the determined configuration of the repeater node.

[0028] In a different aspect, there is provided a repeater node for establishing a device-to-device, D2D, communication via the repeater node. The repeater node is configured to: receive, from a network node, first configuration information which indicates a first configuration for configuring a first side of the repeater node to forward at least first reference signal that the repeater node receives from the network node; and receive, from the network node, second configuration information which indicates a second configuration for configuring a second side of the repeater node to forward at least second reference signal that the repeater node receives from the network node. The repeater node is further configured to, after receiving the first configuration information from the network node, receive said at least first reference signal from the network node; after receiving the second configuration information from the network node, receive said at least second reference signal from the network node; and forward or reflect said at least first reference signal from the first side of the repeater node. The repeater node is further configured to forward or reflect said at least second reference signal from the second side of the repeater node; and receive, from the network node, repeater configuration information indicating an operation mode and / or a configuration of the repeater node for the D2D communication.

[0029] In a different aspect, there is provided an apparatus comprising a processing circuitry; and a memory, said memory containing instructions executable by said processing circuitry, whereby the apparatus is operative to perform the method of any one of the above embodiments.

[0030] Some embodiments of this disclosure enable a direct communication between two UEs even in the absence of a satisfactory direct link, thereby resulting in latency and spectral efficiency gains. Particularly, in some embodiments, both the gNB and the UE-sides of a repeater node are used for D2D communications, thereby extending the range of D2D communications significantly. Moreover, the embodiments of this disclosure inherits other advantages related to sidelink communications, such as enhanced privacy and security, since information is transmitted in a reduced area over authorized devices instead of over the whole public network (including gNB and core network). In this way, the embodiments improve the business case not only for the D2D and sidelink networksbut also for the repeater nodes.BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate various embodiments.

[0032] FIG. 1 shows an exemplary scenario where some embodiments of this disclosure can be applied.

[0033] FIG. 2 shows a conceptual block diagram of a repeater node according to some embodiments.

[0034] FIG. 3 shows a process according to some embodiments.

[0035] FIGS. 4A-4C illustrate an exemplary configuration of a repeater node.

[0036] FIGS. 5A-5C illustrate an exemplary configuration of a repeater node.

[0037] FIG. 6 shows a process according to some embodiments.

[0038] FIG. 7 shows a process according to some embodiments.

[0039] FIG. 8 shows an apparatus according to some embodiments.

[0040] FIG. 9 shows an apparatus according to some embodiments.

[0041] FIG. 10A illustrates a traditional way of performing a communication between user equipments.

[0042] FIG. 10B illustrates a D2D communication.DETAILED DESCRIPTION

[0043] FIG. 1 shows an exemplary scenario 100 where some embodiments of this disclosure can be applied. In the scenario 100, a network node 102 (e.g., a base station such as gNB) is configured to provide a wireless network to network nodes 104, 106, 108, and 112 (e.g., user equipments (UEs)). For simple explanation purpose, in the rest of this disclosure, the network node 102 will be referred to as gNB 102 and the network nodes 104, 106, 108, and 112 will be referred to as UEs or devices 104, 106, 108, and 112. Examples of a UE / device include but are not limited to a mobile phone, a tablet, a watch, a laptop, an Internet -of-Thing (loT) device, a vehicle, etc.

[0044] In traditional wireless (e.g., cellular) network systems, in case two UEs want to communicate with each other, the UEs exchange data via a base station providing a wireless network to the two UEs. In this disclosure, the two UEs which want to communicate with each other may be referred to as "target UEs.” The traditional way of performing a communication between target UEs is illustrated in FIG. 10A.

[0045] As illustrated in FIG. 10A, in the traditional wireless network systems, in case the UE 104 needs totransmit data to the UE 106, the UE 104 transmits the data to the gNB 102 first via an RF link 1002. Upon receiving the data from the UE 104, the gNB 102 forwards the received data to the core network I external internet protocol (IP) network via a backhaul link 1004. Then the data is sent back to the gNB 102 via the backhaul link 1004, and the gNB 102 forwards the data it received from the core network I external IP network to the UE 106 via an RF link 1006.

[0046] Since, in the traditional wireless network systems, the communication between the UEs 104 and 106 is performed via the gNB 102, the communication consumes not only radio resources (e.g., the resources used for transmitting data via the RF links 1002 and 1006) but also backhaul and computing resources (e.g., the resources used for transmitting data via the backhaul link 1004), thereby resulting in a high end-to-end latency. Thus, sometimes it may be desirable for the UEs 104 and 106 to perform a D2D communication.

[0047] An exemplary way of performing a D2D communication between the UEs 104 and 106 is illustrated in FIG. 10B. As illustrated in FIG. 10B, in performing the D2D communication between the UEs 104 and 106, a direct link 1008 between the UE 104 and the UE 106 with good quality is established. This good quality direct link allows the UEs 104 and 106 to communicate directly with low latency.

[0048] In some scenarios, however, a direct link between the UEs 104 and 106 may not be available. For example, in the scenario 100 shown in FIG. 1 , because there is a building 122 in the line of sight (“LoS”) of the UE 104 with respect to the UE 106 (and vice versa) and 106, a direct link between the UEs 104 and 106 may not be available. Similarly, in the scenario 100, a direct link between the UEs 108 and 112 may not be available because there is a building 126 in the LoS of the UE 108 with respect to the UE 112 (and vice versa). In order to solve this problem, according to some embodiments of this disclosure, a repeater node (e.g., NCR, IRS, etc.) 114 is provided to assist a D2D communication between the target UEs even when a direct path between the target UEs is not available.

[0049] FIG. 2 shows a conceptual block diagram of an example of the repeater node 114 implemented using an NCR. As shown in FIG. 2, the repeater node 114 may be split into two functional parts: a mobile termination (MT) part 202 (NCR-MT 202) and a forwarding (Fwd) part 204 (NCR-Fwd 204).

[0050] The NCR-MT 202 is defined as a functional entity for communicating with the gNB 102 via a Control link (C-link) to enable an exchange of control information (e.g., side control information for the control of the NCR- Fwd 204). The NCR-Fwd 204 is defined as a functional entity for performing amplify-and-forwarding of uplink (UL) I downlink (DL) RF signals between the gNB 102 and a UE (e.g., one of the UEs 104-112) via backhaul link and access link. The behavior of the NCR-Fwd 204 is controlled according to the side control information the NCR-MT 202 received from the gNB 102.

[0051] As shown in FIG. 2, the repeater node 114 may have two sides - gNB-side and UE-side. At the gNB-side of the repeater node 114, the antennas used for the C-link (i.e., the antennas used by the NCR-MT 202) may be separated from the antennas used by the NCR-Fwd 204. However, in advanced configurations, the NCR- MT 202 and the NCR-Fwd 204 may share the same antenna configurations at the gNB-side. Also, in its most common architecture, different antenna modules are used for the gNB- and UE-sides, i.e., the antennas targeting the gNB and UEs, respectively, whereas a more complex architecture, including self -interference cancellation, would allow for using the same antenna modules for both sides.

[0052] In case the repeater node 114 is implemented using IRS, the I RS may have the same structure as the structure of the NCR shown in FIG. 2. The MT module of the IRS may be responsible for exchanging information with its controlling gNB and receiving configurations for proper reflections.

[0053] Referring back to FIG. 1, as briefly mentioned above, the repeater node 114 can be used to create an alternative and efficient communication path for a D2D communication between the UEs 104-112. In order to create such efficient communication path, the gNB 102 or another controlling entity should properly configure the repeater node 114 with appropriate configuration (e.g., appropriate beamforming, amplification gain, etc.). Therefore, there is a need for a method to properly configure the repeater node 114 to assist D2D communications between the UEs. Accordingly, in some embodiments of this disclosure, a process 300 shown in FIG. 3 is provided to configure the repeater node 114 to assist D2D communications between the UEs 104-112.

[0054] The process 300 may be triggered by any one or more of triggering factors. One example of such triggering factors is a UE's request to initiate a D2D communication with another UE. Another example of such triggering factors is the gNB 102's detection of its overload state. More specifically, in one example, the gNB 102 may detect that its signal handling capacity reaches a predefined maximum allowed state, and in response to the detection, the gNB 102 may initiate the process 300 to trigger establishing D2D communications between UEs. Such D2D communications may offload some of the operations handled by the gNB 102, thereby allowing the gNB 102 to recover at least some of its signal handling capacity.

[0055] The process 300 may begin with an optional step s302. The step s302 comprises the gNB 102 receiving a capability report which indicates the capability of the repeater node 114. In some embodiments, the gNB 102 may receive the capability report from the repeater node 114. However, in other embodiments, the gNB 102 may receive the capability report from an entity for Operations, Administration and Maintenance (OAM), higher layers, or another network node. The capability report may be received through Radio Resource Control (RRC), Medium Access Control (MAC) Control Elements (MAC-CE), or Uplink Control Information (UCI).

[0056] Note that, in some embodiments, the capability of the gNB-side of the repeater node 114 and the capability of the UE-side of the repeater node 114 may be different. In such embodiments, in the step s302, thegNB 102 may receive a single capability report that indicates the capability of the gNB-side of the repeater node 114 and the capability of the UE-side of the repeater node 114. Alternatively, the gNB 102 may receive two separate capability reports one of which indicates the capability of the gNB-side of the repeater node 114 and another one of which indicates the capability of the UE-side of the repeater node 114.

[0057] The capability report for the gNB-side of the repeater node 114 may include information about one or more of:

[0058] Similarly, the capability report for the UE-side of the repeater node 114 may include information about one or more of:

[0059] In some embodiments, the capability report(s) that the gNB 102 receives in the step s302 may also indicate types of the repeater node 114. For the UE-side of the repeater node 114, possible types of the repeater node 114 are wide-area (WA), medium range (MR), and local-area (LA). On the contrary, for the gNB-side of the repeater node 114, possible types of the repeater node 114 are WA and LA (i. e., MR is not available at the gNB- side).

[0060] In case the gNB 102 receives a single capability report for both sides, both of link type at the UE- side and link type at the gNB-side may be declared in such single capability report (i.e., both link types may be reported jointly). On the other hand, in case the gNB 102 receives two separate capability reports for the UE-side and the gNB-side, the link type at the UE-side of the repeater node 114 may be declared in the capability report corresponding to the UE-side while the link type at the gNB-side of the repeater node 114 may be declared in thecapability report corresponding to the gNB-side of the repeater node 114 (i.e., the link types may be reported separately).

[0061] Even though FIG. 3 shows that the step s302 is a part of the process 300, in some embodiments, the step s302 may be performed separately from the rest of the steps in the process 300. For example, in some embodiments, the gNB 102 may receive the capability report periodically regardless of whether the process 300 is triggered. In another example, the gNB 102 may receive the capability report when the repeater node 114 is initially set up or updated regardless of whether the process 300 is triggered.

[0062] Referring back to FIG. 3, after performing the step s302, the process 300 may proceed to step s304. The step s304 comprises the gNB 102 configuring the repeater node 114 with a configuration related to the UE-side of the repeater node 114. More specifically, in the step s304, the gNB 102 may transmit to the repeater node 114 configuration information indicating the configuration related to the UE-side of the repeater node 114. Here, the configuration related to the UE-side of the repeater node 114 may indicate one or more of: (1) a set of one or more forwarding beams to use for transmitting reference signal(s) by the UE-side of the repeater node; (2) a set of one or more reflection angles or directions to use for transmitting reference signal(s) by the UE-side of the repeater node; and (3) a set of one or more timings at which the configuration should be applied at and / or a set of one or more time intervals during which the configuration should be applied. Note that the repeater node 114 is configured to receive reference signals from the gNB 102 and transmit the reference signals received from the gNB 102. Thus, in the rest of this disclosure, the repeater node 114's transmission of reference signal (s) is referred to as forwarding / reflecting reference signal(s).

[0063] FIGS. 4A and 4B shows an example of the configuration related to the UE-side of the repeater node 114. In the example shown in FIG. 4A, the configuration related to the UE-side of the repeater node 114 identifies five forwarding beams 402-410 of the UE-side to use for forwarding / reflecting (i.e., transmitting) reference signals that the repeater node 114 receives from the gNB 102. Each of the forwarding beams 402-410 of the UE-side of the repeater node 114 may be identified by the configuration information using: (1) a repeater beam index or any other identifier (ID); (2) a repeater beam index / ID + a repeater beam type index / ID; and / or (3) a repeater beam polarization index / ID. In some embodiments, the identifications of the forwarding beams 402-410 may be provided in transmission configuration indicator (TCI).

[0064] Each reflection angle or direction indicated by the configuration of the UE-side of the repeater node 114 may represent the direction in which reference signal(s) received by the repeater node 114 from the gNB 102 are transmitted from the UE-side of the repeater node 114. For example, in FIG. 4B, 9 indicates the reflection angle / direction of forwarding / reflecting reference signal(s) from the repeater node 114.

[0065] Table provided below illustrates a simplified example of the configuration of the UE-side of therepeater node 114.

[0066] In a summary, the configuration related to the UE-side of the repeater node 114 is for configuring the UE-side of the repeater node 114 to use certain beams and / or forwarding directions for forwarding reference signals that the repeater node 114 receives from the gNB 102 at particular timings or during particular time intervals. The configuration may be dynamic, semi-persistent, or periodic.

[0067] In some embodiments, the configuration related to the UE-side of the repeater node 114 may also indicate the types of beams (e.g., a narrow beam vs. a wide beam which may cover a plurality of narrow beams) to use for forwarding the reference signals. For example, in case the repeater node 114 is capable of forming narrower beams 452-456 as shown in FIG. 4G as well as the wider beams 402-410 as shown in FIG. 4A, the configuration related to the UE-side of the repeater node 114 may indicate the followings:

[0068] Referring back to FIG. 3, after performing the step s304, the process 300 may proceed to step s306. The step s306 comprises the gNB 102 transmitting to the repeater node 114 reference signal(s). More specifically, in the step s306, the gNB 102 may transmit to the repeater node 114 a set of reference signals to be forwarded by the UE-side of the repeater node 114.

[0069] After receiving the set of reference signals from the gNB 102, in step s308, the UE-side of the repeater node 114 may forward the received reference signals using the configuration obtained in the step s304. For instance, in the example shown in FIG. 4A, the configuration related to the UE-side of the repeater node 114 indicates the five forwarding beams 402-410 to use for forwarding / reflecting reference signals. In this example, inthe step s308, the repeater node 114 may forward the received reference signals using the five forwarding beams 402-410.

[0070] More specifically, in the example shown in FIG. 4A, the gNB 102 may transmit to the repeater node synchronization signal block (SSB)1 , SSB2, SSB3, SSB4, and SSB5 using a beam 412 that is directed toward the repeater node 114. Upon receiving the SSBs 1 -5, the repeater node 114 may sequentially transmit the SSBs 1 -5 using the beams 402-410 respectively. Here, note that the number of SSBs transmitted from the gNB 102 to the repeater node 114 is same as the number of TX beams at the UE-side of the repeater node 114 to use for forwarding / reflecting reference signals. Even though SSBs are used as examples in FIG. 4A, any other reference signals (e.g., CSI-RS) may be used instead.

[0071] After the repeater node 114 transmits the reference signals, the process 300 may proceed to step s310. The step s310 comprises the gNB 102 receiving a report message from each UE which received the reference signals transmitted by the repeater node 114 in the step s308. The gNB 102 may receive the report message directly from UE(s) or indirectly from UE(s) via the repeater node 114. The report message may indicate a result of a UE measuring the reference signal(s) received at the UE. The measurement result may indicate one or more of the following metrics: signal gain, reference signal received power (RSRP), signal -to-interference-plus-noise ratio (SI NR), signal-to-noise ratio (SNR), and reference signal received quality (RSRQ).

[0072] In some embodiments, the measurement result may indicate a TX beam of the repeater node 114 used for forwarding / reflecting reference signal(s) received at a UE, resulting in the highest measurement at the UE. For instance, in the example shown in FIG. 4A, the UE 112 receive reference signals transmitted via the beams 402-410, and among the received reference signals, the reference signal received via the beam 406 provides the highest measurement.

[0073] More specifically, in one example, the strength of the reference signal received via the beam 406 is greater than any of the strength of the reference signals received via the beams 402, 404, 408, and 410. In this example, the UE 112 may transmit to the gNB 102 a report message identifying the beam 406 and one or more of the following metrics associated with the reference signal(s) transmitted via the beam 406: signal gain, RSRP, SINR, SNR, and / or RSRQ.

[0074] In some embodiments, the measurement result may indicate N number of TX beam of the repeater node 114. The N number of TX beams indicated in the measurement result may correspond to the beams used for forwarding / reflecting reference signals received at the UE, which result in the N highest measurements at the UE from among the TX beams available at the UE-side of the repeater node 114.

[0075] In some embodiments, the repeater node 114 may be capable of forming different types of beams.In such embodiments, the configuration related to the UE-side of the repeater node 114 may indicate different types of beams to use for forwarding reference signals. Also in such embodiments, the step s306 may be performed for different types of beams.

[0076] For example, the configuration related to the UE-side may identify the wider forward beams 402- 410 and the narrower forward beams associated with each of the wide forward beams. FIG. 40 shows an example of the narrower forward beams 452-456 that are associated with the wider forward beam 406. Then, after receiving from the UE 112 the report message indicating the beam 406 in the step s310, the gNB 102 may transmit to the repeater node 114 reference signals (e.g., CSI-RS) and the repeater node 114 may forward the received reference signals to the UE 112 via the narrow forward beams 452-456. Then, the gNB 102 may receive another report message identifying a narrow forward beam (e.g., the beam 454) which was used for transmitting the reference signal received at the UE 112, resulting in the highest measurement at the UE 112. The report message may also indicate one or more of the above discussed metrics that are associated with the reference signal transmitted via the beam 454.

[0077] In a summary, the transmission of the reference signals via the beams 402-410 is for finding a coarse direction of the UE 112 with respect to the repeater node 114 and the transmission of the reference signals via the beams 454-456 is for finding a relatively accurate direction of the UE 112 with respect to the repeater node 114.

[0078] As discussed above, the steps s304-s310 are performed for the UE-side of the repeater node 114. In some embodiments, the same steps may be performed for the gNB-side of the repeater node 114. More specifically, the process 300 may proceed to steps s312-s318. Note that the steps s304-s310 may be performed prior to or after performing the steps s312-s318. Alternatively, the steps s304-s310 may be performed simultaneously with the steps s312-s318.

[0079] The step s312 comprises the gNB 102 configuring the repeater node 114 with a configuration related to the gNB-side of the repeater node 114. More specifically, in the step s312, the gNB 102 may transmit to the repeater node 114 configuration information indicating the configuration related to the gNB-side of the repeater node 114. Here, the configuration related to the gNB-side of the repeater node 114 may indicate one or more of: (1) a set of one or more forwarding beams to use for forwarding / reflecting reference signal(s) by the gNB-side of the repeater node; (2) a set of one or more reflection angles or directions to use for forwarding / reflecting reference signal(s) by the gNB-side of the repeater node; and (3) a set of one or more timings at which the configuration should be applied at and / or a set of one or more time intervals during which the configuration should be applied.

[0080] FIGS. 5A and 5B show an example of the configuration related to the gNB-side of the repeater node 114. In the example shown in FIG. 5A, the configuration related to the gNB -side of the repeater node 114 identifiesfive forwarding beams 502-510 of the gNB-side to use for forwarding / reflecting (i.e., transmitting) reference signals that the repeater node 114 receives from the gNB 102. Each of the forwarding beams 502-510 of the gNB-side of the repeater node 114 may be identified by the configuration information using: (1) a repeater beam index or any other identifier (ID); (2) a repeater beam index / ID + a repeater beam type index / ID; and / or (3) a repeater beam polarization index / ID. In some embodiments, the identifications of the forwarding beams 402-410 may be provided in transmission configuration indicator (TCI).

[0081] Each reflection angle or direction indicated by the configuration of the gNB-side of the repeater node 114 may represent the direction in which reference signal(s) received by the repeater node 114 from the gNB 102 are transmitted from the gNB-side of the repeater node 114. For example, in FIG. 5B, 9 indicates the reflection angle / direction of forwarding / reflecting reference signal(s) from the repeater node 114.

[0082] Table provided below illustrates a simplified example of the configuration of the UE-side of the repeater node 114.

[0083] In a summary, the configuration related to the gNB-side of the repeater node 114 is for configuring the gNB-side of the repeater node 114 to use certain beams and / or forwarding directions for forwarding reference signals that the repeater node 114 receives from the gNB 102 at particular timings or during particular time intervals. The configuration may be dynamic, semi-persistent, or periodic.

[0084] In some embodiments, the configuration related to the gNB -side of the repeater node 114 may also indicate the types of beams (e.g., a narrow beam vs. a wide beam which may cover a plurality of narrow beams) to use for forwarding the reference signals. For example, in case the repeater node 114 is capable of forming narrower beams 552-556 as shown in FIG. 5C as well as the wider beams 502-510 as shown in FIG. 5A, the configuration related to the gNB-side of the repeater node 114 may indicate the followings:

[0085] Referring back to FIG. 3, after performing the step s312, the process 300 may proceed to step s314. The step s314 comprises the gNB 102 transmitting to the repeater node 114 reference signal(s). More specifically, in the step s314, the gNB 102 may transmit to the repeater node 114 a set of reference signals for the gNB-side of the repeater node 114.

[0086] After receiving the set of reference signals from the gNB 102, in step s316, the repeater node 114 may forward the received reference signals by the gNB-side using the configuration obtained in the step s312. For instance, in the example shown in FIG. 5A, the configuration related to the gNB-side of the repeater node 114 indicates the five forwarding beams 502-510 to use for forwarding / reflecting reference signals. In this example, in the step s316, the repeater node 114 may forward the received reference signals using the five forwarding beams 502-510.

[0087] More specifically, in the example shown in FIG. 5A, the gNB 102 may transmit to the repeater node synchronization signal block (SSB)1 , SSB2, SSB3, SSB4, and SSB5 using a beam 412 that is directed toward the repeater node 114. Upon receiving the SSBs 1 -5, the repeater node 114 may sequentially transmit the SSBs 1 -5 using the beams 502-510 respectively. Here, the number of SSBs transmitted from the gNB 102 to the repeater node 114 is same as the number of TX beams at the UE-side of the repeater node 114 to use for forwarding / reflecting reference signals. However, in some embodiments, the number of the SSBs may be different from the number of the TX beams. Even though SSBs are used as examples in FIG. 5A, any other reference signals (e.g., CSI -RS) may be used instead.

[0088] After the repeater node 114 transmits the reference signals, the process 300 may proceed to step s318. The step s318 comprises the gNB 102 receiving a report message from each UE which received the reference signals transmitted by the repeater node 114 in the step s316. The gNB 102 may receive the report message directly from UE(s) or indirectly from UE(s) via the repeater node 114. The report message may indicate a result of a UE measuring the reference signal(s) received at the UE. The measurement result may indicate one or more of the following metrics: signal gain, reference signal received power (RSRP), signal -to-interference-plus-noise ratio (SI NR), signal-to-noise ratio (SNR), and reference signal received quality (RSRQ).

[0089] In some embodiments, the measurement result may indicate a TX beam of the repeater node 114 used for forwarding / reflecting reference signal(s) received at a UE, resulting in the highest measurement at the UE. For instance, in the example shown in FIG. 5A, the UE 106 receive reference signals transmitted via the beams502-510, and among the received reference signals, the reference signal received via the beam 506 provides the highest measurement.

[0090] More specifically, in one example, the strength of the reference signal received via the beam 506 is greater than any of the strength of the reference signals received via the beams 502, 504, 508, and 510. In this example, the UE 106 may transmit to the gNB 102 a report message identifying the beam 506 and one or more of the following metrics associated with the reference signal(s) transmitted via the beam 506: signal gain, RSRP, SINR, SNR, and / or RSRQ.

[0091] In some embodiments, the measurement result may indicate N number of TX beam of the repeater node 114. The N number of TX beams indicated in the measurement result may correspond to the beams used for forwarding / reflecting reference signals received at the UE, which result in the N highest measurements at the UE from among the TX beams available at the gNB-side of the repeater node 114.

[0092] In some embodiments, the repeater node 114 may be capable of forming different types of beams. In such embodiments, the configuration related to the gNB-side of the repeater node 114 may indicate different types of beams to use for forwarding reference signals. Also in such embodiments, the step s314 may be performed for different types of beams.

[0093] For example, the configuration related to the gNB-side may identify the wider forward beams 502- 510 and the narrower forward beams associated with each of the wide forward beams. FIG. 5C shows an example of the narrower forward beams 552-556 that are associated with the wider forward beam 506. Then, after receiving from the UE 106 the report message indicating the beam 506 in the step s318, the gNB 102 may transmit to the repeater node 114 reference signals (e.g., CSI-RS) and the repeater node 114 may forward the received reference signals to the UE 106 via the narrow forward beams 552-556. Then, the gNB 102 may receive another report message identifying a narrow forward beam (e.g., the beam 554) which was used for forwarding / reflecting the reference signal received at the UE 106, resulting in the highest measurement at the UE 106. The report message may also indicate one or more of the above discussed metrics that are associated with the reference signal transmitted via the beam 554.

[0094] Note that, according to the embodiments described above, the repeater assisted D2D communications are enabled at both the UE-side and the gNB-side of the repeater node 114. This allows extending the range of D2D communications between UEs.

[0095] Even though FIGS. 4A and 5A show that the number of beams at the UE-side of the repeater node 114 used for forwarding / reflecting reference signals from the UE-side and the number of beams at the gNB-side of the repeater node 114 used for forwarding / reflecting reference signals from the gNB-side are the same, in someembodiments, they may be different. Also, the types of beams available at the UE-side and the gNB-side may be same or different depending on the capability of the UE-side and the capability of the gNB-side.

[0096] In the embodiments described above, different beam indicators (index / ID) are used to identify beams at the UE-side and beams at the gNB-side of the repeater node 114. However, in some embodiments, the same beam indicators may be used to identify the beams at the UE-side and the beams at the gNB-side. For instance, in the examples shown in FIGS. 4A and 5A, the beam 408 and the beam 506 may be assigned with the same beam indicator.

[0097] As explained above with respect to the steps s304 and s312, the gNB 102 may configure the UE- side and the gNB-side of the repeater node 114 separately. Thus, when the gNB 102 transmits the configuration information to the repeater node 114, the gNB 102 may need to indicate whether the transmitted configuration information is for the UE-side or the gNB-side. Therefore, according to some embodiments, the configuration information that the gNB 102 transmits to the repeater node 114 may include a flag indicating whether the configuration information is for the UE-side or the gNB-side of the repeater node 114.

[0098] As briefly mentioned above, one of the important aspects of some embodiments of this disclosure is the use of the gNB-side of the repeater node 114. The gNB-side of the repeater node 114 is traditionally reserved for communicating with the gNB. However, as explained above, in some embodiments of this disclosure, the gNB- side of the repeater node 114 can be configured to assist a D2D communication between target UEs. This is specially for LA repeaters where the gNB-side is in the order of height as the UEs and can be reached by the UEs for D2D communication.

[0099] Referring back to FIG. 3, after performing the steps s310 and s318, the process 300 may proceed to step s320. The step s320 comprises, based on the report messages that the gNB 102 received in the steps 310 and s318, the gNB 102 determines an operation mode and / or a configuration of the repeater node 114 for assisting a D2D communication between target UEs. In some embodiments, the step s320 may also comprise the gNB 102 determining the configuration(s) of the target UEs for the D2D communication.

[0100] The operation mode of the repeater node 114 may be selected from the following modes:

[0101] As shown above, in Mode 1 , only the gNB-side of the repeater node 114 is used. Thus, in Mode 1, the transmitter(s) and the receiver(s) of the repeater node 114, which are for providing the gNB-side link of the repeater node 114 may set to be ON. Here, the beam configuration for the gNB-side link of the repeater node 114in Mode 1 may be different from the beam configuration for the gNB-side link when the gNB-side link is used for backhaul / control communication with the gNB 102. On the contrary, since the UE-side of the repeater 114 is not used in Mode 1 , the transmitter(s) and the receiver(s) of the repeater node 114, which are for providing the UE-side link of the repeater node 114 may set to be OFF.

[0102] In Mode 4, only the UE-side of the repeater node 114 is used. Thus, in Mode 4, the transmitter(s) and the receiver(s) of the repeater node 114, which are for providing the UE-side link of the repeater node 114 may set to be ON while the transmitter(s) and the receiver(s) of the repeater node 114, which are for providing the gNB- side link of the repeater node 114 may set to be OFF. Note that, in some embodiments, the hardware (e.g., transmitter(s) and / or receiver(s)) of the repeater node 114 for providing the control link may be different from the hardware of the repeater node 114 for providing the backhaul link. In such embodiments, in Mode 4, the hardware of the repeater node 114 for providing the control link may continue to be ON while the hardware of the repeater node 114 for providing the backhaul link may be set to be OFF.

[0103] As compared to Modes 1 and 4, in Modes 2 and 3, both the gNB-side and the UE-side of the repeater node 114 are used. Thus, in these modes, the transmitter(s) and the receiver(s) of the repeater node 114, which are for providing the gNB-side link and the transmitter(s) and the receiver(s) of the repeater node 114, which are for providing the UE-side link of the repeater node 114 may set to be ON with specific beam configurations.

[0104] In Mode 5, both the gNB-side and the UE-side of the repeater node 114 may not need to be used. Thus, in Mode 5, the transmitter(s) and the receiver(s) of the repeater node 114, which are for providing the gNB- side link and the transmitter(s) and the receiver(s) of the repeater node 114, which are for providing the UE -side link of the repeater node 114 may set to be OFF. Alternatively, in case the transmitter(s) and the receiver(s) of the repeater node 114, which are for providing the control link are provided separately from the transmitter(s) and the receiver(s) of the repeater node 114, which are for providing the backhau l link, in Mode 5, the transmitter(s) and the receiver(s) of the repeater node 114, which are for providing the control link may set to be ON while the transmitter(s) and the receiver(s) of the repeater node 114, which are for providing the backhaul link can be set to be OFF.

[0105] The following examples illustrate how the operation mode of the repeater node 114 may be changed based on the locations of the UEs.

[0106] In one example, an LoS of the UE 104 with respect to the UE 108 (and vice versa) is not blocked. In this case, a D2D communication can be established between the UEs 104 and 108 without the repeater node 114 and thus the operation mode of the repeater node 114 for the D2D communication between the UEs 104 and 108 may set to be Mode 5.

[0107] In another example, an LoS of the UE 104 with respect to the UE 106 (and vice versa) is blocked .In this case, the operation mode of the repeater node 114 for the D2D communication between the UEs 104 and 106 is set to be Mode 1 because both the UEs 104 and 106 are disposed on the gNB-side of the repeater node 114.

[0108] In further example, because both the UEs 108 and 112 are disposed on the UE-side of the repeater node 114, the operation mode of the repeater node 114 for the D2D communication between the UEs 108 and 112 is Mode 4.

[0109] The configurations of the repeater node 114 determined in the step s320 may include ON / OFF configurations of the transmitters and the receivers at the UE-side and the gNB-side of the repeater node 114 (which are explained above). The determined configurations of the repeater node 114 may also indicate forwarding beam(s) and reflection angle(s) / direction(s) to use at the gNB-side and / or the UE-side of the repeater node for a D2D communication. The determined configurations may also indicate timings at which the determined configurations should be applied and / or time intervals during which the determined configurations should be applied.

[0110] The configuration of the target UEs (i.e., the D2D UEs) determined in the step s320 may indicate one or more of: (1) whether a D2D operation is enabled; (2) a proper beam configuration; (3) proper power control; (4) proper modulation and coding, etc.[OHl] After determining the operation mode of the repeater node 114 and the configurations of the repeater node 114 and the target UEs, the process 300 may proceed to step s322. The step s322 comprises the gNB 102 transmitting to the repeater node 114 repeater configuration information indicating the determined operation mode of the repeater node 114 and the determined configurations of the repeater node 114. The step s322 may also comprise the gNB 102 transmitting to the target UEs D2D configuration information indicating the determined configurations of the target UEs. Here, transmitting the D2D configuration information to the target UEs may be performed based on the state-of-the-art sidelink methods as the repeater node 114 is transparent to the target UEs.

[0112] As explained above, the determined configurations of the repeater node 114 may include the ON / OFF configurations of the transmitter(s) and the receiver(s) at the UE-side of the repeater node 114 and the ON / OFF configurations of the transmitter(s) and the receiver(s) at the gNB-side of the repeater node 114. The determined configurations for the two sides of the repeater node 114 may be signaled to the repeater node 114 either jointly or separately.

[0113] The ON / OFF configurations may be signaled to the repeater node 114 either implicitly or explicitly. In case the ON / OFF configurations are signaled explicitly, the repeater configuration information that the gNB 102 transmits to the repeater node 114 may include information elements of which values specifying the ON / OFF configurations of the UE-side and the gNB-side of the repeater node 114.

[0114] On the contrary, in case the ON / OFF configurations are signaled implicitly, such implicit signaling may be performed using beam configuration(s) for the UE-side and / or the gNB-side of the repeater node 114. For example, in case, the repeater configuration information includes the beam configuration(s) for the UE-side, then the repeater node 114 would know that the transmitter(s) and / or the receiver(s) at the UE -side should be ON. On the other hand, in case the repeater configuration information does not include the beam configuration(s) for the gNB-side, then the repeater node 114 would know that the transmitter(s) and / or the receiver(s) at the gNB-side should be OFF.

[0115] In the embodiments disclosed above, only TX beams of the repeater node 114 are discussed. This is because, in the repeater node 114, a TX beam of an RF link of the repeater node 114 is the RX beam for the RF link. For instance, in the example shown in FIG. 40, the beam 454 may serve as a TX beam when the repeater node 114 transmits data to the UE 1 12 while serving as a RX beam when the repeater node 1 14 receives data from the UE 112.

[0116] FIG. 6 shows a process 600 for establishing a device-to-device, D2D, communication via a repeater node (e.g., 114). The process 600 is performed by a network node (e.g., gNB 102). The process 600 may begin with step s602. The step s602 comprises transmitting, to the repeater node, first configuration information which indicates a first configuration for configuring a first side of the repeater node to forward at least first reference signal that the repeater node receives from the network node. The step s604 comprises transmitting, to the repeater node, second configuration information which indicates a second configuration for configuring a second side of the repeater node to forward at least second reference signal that the repeater node receives from the network node. The step s606 comprises, after transmitting the first configuration information to the repeater node, transmitting said at least first reference signal to the repeater node. The step s608 comprises, after transmitting the second configuration information to the repeater node, transmitting said at least second reference signal to the repeater node. The step s610 comprises, after transmitting said at least first and second reference signals to the repeater node, receiving a first report message from a first device, wherein the first report message indicates a measurement result of one of said at least first and second reference signals received at the first device via the repeater node. The step s612 comprises, after transmitting said at least first and second reference signals to the repeater node, receiving a second report message from a second device, wherein the second report message indicates a measurement result of one of said at least first and second reference signals received at the second device via the repeater node. The step s614 comprises, based on the measurement results, determining, for the D2D communication, an operation mode and / or a configuration of the repeater node. The step s616 comprises transmitting, to the repeater node, repeater configuration information indicating the determined operation mode and / or the determined configuration of the repeater node.

[0117] In some embodiments, the first side of the repeater node is configured to establish a control / backhaul link with the network node, the first side of the repeater node is capable of establishing an access link with a device,and the second side of the repeater node is capable of establishing an access link with a device.

[0118] In some embodiments, said at least first reference signal is received at the first device via the first side of the repeater node and said at least second reference signal is received at the second device via the first side of the repeater node, said at least first reference signal is received at the first device via the first side of the repeater node and said at least second reference signal is received at the second device via the second side of the repeater node, said at least first reference signal is received at the first device via the second side of the repeater node and said at least second reference signal is received at the second device via the first side of the repeater node, or said at least first reference signal is received at the first device via the second side of the repeater node and said at least second reference signal is received at the second device via the second side of the repeater node.

[0119] In some embodiments, each of the first and second configurations indicates one or more of: I) one or more forwarding directions for forwarding one or more reference signals from the first side of the repeater node, ii) one or more forwarding directions for forwarding one or more reference signals from the second side of the repeater node, ill) one or more transmit, TX, beams of the first side of the repeater node to use for forwarding one or more reference signals, iv) one or more TX beams of the second side of the repeater node to use for forwarding one or more reference signals, and / or v) one or more timings at which the first or second configuration is to be applied to the repeater node and / or one or more time intervals during which the first or second configuration is to be applied to the repeater node.

[0120] In some embodiments, transmitting the first configuration information to the repeater node comprises transmitting, to the repeater node, a first configuration message indicating the first configuration, transmitting the second configuration information to the repeater node comprises transmitting, to the repeater node, a second configuration message indicating the second configuration, the first configuration message comprises a flag value indicating that the first configuration is for configuring the first side of the repeater node, and the second configuration message comprises a flag value indicating that the second configuration is for configuring the second side of the repeater node.

[0121] In some embodiments, the first report message indicates quality of reference signals received at the first device via a plurality of TX beams at the first side of the repeater node and the second report message indicates quality of reference signals received at the second device via the plurality of TX beams at the first side of the repeater node, the first report message indicates quality of reference signals received at the first device via the plurality of TX beams at the first side of the repeater node and the second report message indicates quality of reference signals received at the second device via a plurality of TX beams at the second side of the repeater node, the first report message indicates quality of reference signals received at the first device via the plurality of TX beams at the second side of the repeater node and the second report message indicates quality of reference signals received at the second device via the plurality of TX beams at the first side of the repeater node, or the first report message indicates qualityof reference signals received at the first device via the plurality of TX beams at the second side of the repeater node and the second report message indicates quality of reference signals received at the second device via the plurality of TX beams at the second side of the repeater node.

[0122] In some embodiments, the first report message indicates a first TX beam at the first side of the repeater node, which is in the direction of the first device and the second report message indicates a second TX beam at the first side of the repeater node, which is in the direction of the second device, the first report message indicates the first TX beam at the first side of the repeater node, which is in the direction of the first device and the second report message indicates a third TX beam at the second side of the repeater node, which is in the direction of the second device, the first report message indicates a fourth TX beam at the second side of the repeater node, which is in the direction of the first device and the second report message indicates the second TX beam at the first side of the repeater node, which is in the direction of the second device, or the first report message indicates the fourth TX beam at the second side of the repeater node, which is in the direction of the first device and the second report message indicates the third TX beam at the second side of the repeater node, which is in the direction of the second device.

[0123] In some embodiments, the operation mode of the repeater node is any one of: (i) receiving one or more signals at the first side of the repeater node and forwarding the received one or more signals from the second side of the repeater node; (ii) receiving one or more signals at the first side of the repeater node and forwarding the received one or more signals from the first side of the repeater node; (iii) receiving one or more signals at the second side of the repeater node and forwarding the received one or more signals from the first side of the repeater node; (iv) receiving one or more signals at the second side of the repeater node and forwarding the received one or more signals from the second side of the repeater node.

[0124] In some embodiments, in the operation mode (ii), a transmitter and / or a receiver for providing the access link at the second side is configured to be off while a transmitter and / or a receiver for providing the access link at the first side is configured to be on, and in the operation mode (iv), the transmitter and / or the receiver for providing the access link at the first side is configured to be off while the transmitter and / or tje receiver for providing the access link at the second side is configured to be on.

[0125] In some embodiments, the configuration of the repeater node indicates: a first beam to use at the first side of the repeater node for the D2D communication for the first device and a second beam to use at the first side of the repeater node for the D2D communication for the second device, the first beam to use at the first side of the repeater node for the D2D communication for the first device and a third beam to use at the second side of the repeater node for the D2D communication for the second device, a fourth beam to use at the second side of the repeater node for the D2D communication for the first device and the second beam to use at the first side of the repeater node for the D2D communication for the second device, or the fourth beam to use at the second side of the repeater node for theD2D communication for the first device and the third beam to use at the second side of the repeater node for the D2D communication for the second device.

[0126] In some embodiments, the repeater configuration information includes one or more of: a beam identifier, ID, (e.g., a beam index) identifying the first beam or the fourth beam; a beam ID identifying the second beam or the third beam; a beam type ID identifying a type of the first beam or the fourth beam; a beam type ID identifying a type of the second beam or the third beam; a beam polarization ID identifying a polarization of the first beam or the fourth beam; and / or a beam polarization ID identifying a polarization of the second beam or the third beam.

[0127] In some embodiments, the process 600 comprises obtaining capability information about the repeater node, wherein the capability information indicates one or more of: a number of beams and / or a type of beams available at the first side of the repeater node; a number of beams and / or a type of beams available at the second side of the repeater node; how quickly the repeater node can switch its beams at the first side; how quickly the repeater node can switch its beams at the second side; how quickly the repeater node can decode beam setting related control information; power control capability of the repeater node at the first side; power control capability of the repeater node at the second side; on / off capability of the repeater node at the first side; on / off capability of the repeater node at the second side; antenna configurations at the first side of the repeater node; and / or antenna configurations at the second side of the repeater node.

[0128] In some embodiments, the capability information indicates a type of the repeater node at the first side and / or a type of the repeater node at the second side, the type of the repeater node at the first side is selected from a group consisting of wide-area, WA, medium range, MR, and local-area, LA, and the type of the repeater node at the second side is selected from a group consisting of WA and LA.

[0129] In some embodiments, the repeater node is either a network-controlled repeater, NCR, or an intelligent reflective surface, IRS.

[0130] FIG. 7 shows a process 700 performed by a repeater node (114) for establishing a device-to-device, D2D, communication via the repeater. The process 700 may begin with step s702. The step s702 comprises receiving, from a network node, first configuration information which indicates a first configuration for configuring a first side of the repeater node to forward at least first reference signal that the repeater node receives from the network node. The step s704 comprises receiving, from the network node, second configuration information which indicates a second configuration for configuring a second side of the repeater node to forward at least second reference signal that the repeater node receives from the network node. The step s706 comprises after receiving the first configuration information from the network node, receiving said at least first reference signal from the network node. The step s708 comprises after receiving the second configuration information from the network node, receiving said at least second reference signal from the network node. The step s710 comprises forwarding or reflecting said at least first referencesignal from the first side of the repeater node. The step s712 comprises forwarding or reflecting said at least second reference signal from the second side of the repeater node. The step s714 comprises receiving, from the network node, repeater configuration information indicating an operation mode and / or a configuration of the repeater node for the D2D communication.

[0131] In some embodiments, the first side of the repeater node is configured to establish a control / backhaul link with the network node, the first side of the repeater node is capable of establishing an access link with a device, and the second side of the repeater node is capable of establishing an access link with a device.

[0132] In some embodiments, each of the first and second configurations indicates one or more of: i) one or more forwarding directions for forwarding one or more reference signals from the first side of the repeater node, ii) one or more forwarding directions for forwarding one or more reference signals from the second side of the repeater node, iii) one or more transmit, TX, beams of the first side of the repeater node to use for forwarding one or more reference signals, iv) one or more TX beams of the second side of the repeater node to use for forwarding one or more reference signals, and / or v) one or more timings at which the first or second configuration is to be applied to the repeater node and / or one or more time intervals during which the first or second configuration is to be applied to the repeater node.

[0133] In some embodiments, receiving the first configuration information from the network node comprises receiving, from the network node, a first configuration message indicating the first configuration, receiving the second configuration information from the network node comprises receiving, from the network node, a second configuration message indicating the second configuration, the first configuration message comprises a flag value indicating that the first configuration is for configuring the first side of the repeater node, and the second configuration message comprises a flag value indicating that the second configuration is for configuring the second side of the repeater node.

[0134] In some embodiments, the operation mode of the repeater node is any one of: (i) receiving one or more signals at the first side of the repeater node and forwarding the received one or more signals from the second side of the repeater node; (ii) receiving one or more signals at the first side of the repeater node and forwarding the received one or more signals from the first side of the repeater node; (iii) receiving one or more signals at the second side of the repeater node and forwarding the received one or more signals from the first side of the repeater node; or (iv) receiving one or more signals at the second side of the repeater node and forwarding the received one or more signals from the second side of the repeater node.

[0135] In some embodiments, in the operation mode (ii), a transmitter and / or a receiver for providing the link of the second side is configured to be off, and in the operation mode (iv), a transmitter and / or a receiver for providing the link of the first side is configured to be off.

[0136] In some embodiments, the D2D communication is between a first device and a second device, andthe configuration of the repeater node indicates: a first beam to use at the first side of the repeater node for the D2D communication for the first device and a second beam to use at the first side of the repeater node for the D2D communication for the second device, the first beam to use at the first side of the repeater node for the D2D communication for the first device and a third beam to use at the second side of the repeater node for the D2D communication for the second device, a fourth beam to use at the second side of the repeater node for the D2D communication for the first device and the second beam to use at the first side of the repeater node for the D2D communication for the second device, or the fourth beam to use at the second side of the repeater node for the D2D communication for the first device and the third beam to use at the second side of the repeater node for the D2D communication for the second device.

[0137] In some embodiments, the repeater configuration information includes one or more of: a beam identifier, ID, (e.g., a beam index) identifying the first beam or the fourth beam; a beam ID identifying the second beam or the third beam; a beam type ID identifying a type of the first beam or the fourth beam; a beam type ID identifying a type of the second beam or the third beam; a beam polarization ID identifying a polarization of the first beam or the fourth beam; and / or a beam polarization ID identifying a polarization of the second beam or the third beam.

[0138] In some embodiments, the process 700 comprises transmitting, to the network node, capability information about the repeater node, wherein the capability information indicates one or more of: a number of beams and / or a type of beams available at the first side of the repeater node; a number of beams and / or a type of beams available at the second side of the repeater node; how quickly the repeater node can switch its beams at the first side; how quickly the repeater node can switch its beams at the second side; how quickly the repeater node can decode beam setting related control information; power control capability of the repeater node at the first side; power control capability of the repeater node at the second side; on / off capability of the repeater node at the first side; on / off capability of the repeater node at the second side; antenna configurations at the first side of the repeater node; and / or antenna configurations at the second side of the repeater node.

[0139] In some embodiments, the capability information indicates a type of the repeater node at the first side and / or a type of the repeater node at the second side, the type of the repeater node at the first side is selected from a group consisting of wide-area, WA, medium range, MR, and local-area, LA, and the type of the repeater node at the second side is selected from a group consisting of WA and LA.

[0140] In some embodiments, the repeater node is either a network-controlled repeater, NCR, or an intelligent reflective surface, IRS.

[0141] FIG. 8 is a block diagram of the gNB 102, according to some embodiments. As shown in FIG. 8, the gNB 102 may comprise: processing circuitry (PC) 802, which comprises one or more processors (P) 855 (e.g., a general purpose microprocessor and / or one or more other processors, such as an application specific integ ratedcircuit (ASIC), field-programmable gate arrays (FPGAs), and the like), which processors may be co -located in a single housing or in a single data center or may be geographically distributed (i.e., the gNB may be a distributed computing apparatus or a monolithic computing apparatus); a network interface 868 comprising a transmitter (Tx) 865 and a receiver (Rx) 867 for enabling the gNB 102 to transmit data to and receive data from other nodes connected to a network 110 (e.g., an Internet Protocol (IP) network) to which network interface 868 is connected; communication circuitry 848 (e.g., radio transceiver circuitry comprising an Rx 847 and a Tx 845) coupled to an antenna system 849 for wireless communication with UEs or other nodes; and a storage unit (a.k.a., "data storage system”) 808, which may include one or more non-volatile storage devices and / or one or more volatile storage devices. In embodiments where PC 802 includes a programmable processor, a computer readable storage medium (CRSM) 842 may be provided. CRSM 842 may store a computer program (CP) 843 comprising computer readable instructions (CRI) 844. CRSM 842 may be a non-transitory computer readable medium, such as, magnetic media (e.g., a hard disk), optical media, memory devices (e.g., random access memory, flash memory), and the like. In some embodiments, the CRI 844 of computer program 843 is configured such that when executed by PC 802, the CRI causes the gNB 102 to perform steps described herein (e.g., steps described herein with reference to one or more flow charts). In other embodiments, the gNB 102 may be configured to perform steps described herein without the need for code. That is, for example, PC 802 may consist merely of one or more ASICs. Hence, the features of the embodiments described herein may be implemented in hardware and / or software.

[0142] FIG. 9 is a block diagram of network node 900 forming the repeater node 114, according to some embodiments. As shown in FIG. 9, network node 900 may comprise: processing circuitry (PC) 902, which comprises one or more processors (P) 955 (e.g., one or more general purpose microprocessors and / or one or more other processors, such as an application specific integrated circuit (ASIC), field -programmable gate arrays (FPGAs), and the like), which processors may be co-located in a single housing or in a single data center or may be geographically distributed (e.g., network node 900 may be a distributed computing apparatus comprising two or more computers or a monolithic computing apparatus consisting of a single computer); at least one network interface 948 (e.g., a physical interface or air interface) comprising a transmitter (Tx) 945 and a receiver (Rx) 947 for enabling network node 900 to transmit data to and receive data from other nodes connected to network 110 (e.g., an Internet Protocol (IP) network) to which network interface 948 is connected (physically or wirelessly) (e.g., network interface 948 may be coupled to an antenna arrangement comprising one or more antennas for enabling network node 900 to wirelessly transmit / receive data); and a storage unit (a.k.a., "data storage system”) 908, which may include one or more non-volatile storage devices and / or one or more volatile storage devices. In embodiments where PC 902 includes a programmable processor, a computer readable storage mediu m (CRSM) 942 may be provided. CRSM 942 may store a computer program (CP) 943 comprising computer readable instructions (CRI) 944. CRSM 942 may be a non-transitory computer readable medium, such as, magnetic media (e.g., a hard disk), optical media, memorydevices (e.g., random access memory, flash memory), and the like. In some embodiments, the CRI 944 of computer program 943 is configured such that when executed by PC 902, the CRI causes network node 900 to perform steps described herein (e.g., steps described herein with reference to the flow charts). In other embodiments, network node 900 may be configured to perform steps described herein without the need for code. That is, for example, PC 902 may consist merely of one or more ASICs. Hence, the features of the embodiments described herein may be implemented in hardware and / or software.

[0143] While various embodiments are described herein, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of this disclosure should not be limited by any of the above-described exemplary embodiments. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the disclosure unless otherwise indicated herein or otherwise clearly contradicted by context.

[0144] As used herein transmitting a message "to” or "toward” an intended recipient encompasses transmitting the message directly to the intended recipient or transmitting the message indirectly to the intended recipient (i.e., one or more other nodes are used to relay the message from the source node to the intended recipient). Likewise, as used herein receiving a message "from” a sender encompasses receiving the message directly from the sender or indirectly from the sender (i.e., one or more nodes are used to relay the message from the sender to the receiving node). Further, as used herein "a” means "at least one” or "one or more.”

[0145] Additionally, while the processes described above and illustrated in the drawings are shown as a sequence of steps, this was done solely for the sake of illustration. Accordingly, it is contemplated that some steps may be added, some steps may be omitted, the order of the steps may be re-arranged, and some steps may be performed in parallel.

Claims

CLAIMS1. A method (600) for establishing a device-to-device, D2D, communication via a repeater node (114), the method being performed by a network node (102), the method comprising: transmitting (s602), to the repeater node, first configuration information which indicates a first configuration for configuring a first side of the repeater node to forward at least first reference signal that the repeater node receives from the network node; transmitting (s604), to the repeater node, second configuration information which indicates a second configuration for configuring a second side of the repeater node to forward at least second reference signal that the repeater node receives from the network node; after transmitting the first configuration information to the repeater node, transmitting (s606) said at least first reference signal to the repeater node; after transmitting the second configuration information to the repeater node, transmitting (s608) said at least second reference signal to the repeater node; after transmitting said at least first and second reference signals to the repeater node, receiving (s610) a first report message from a first device, wherein the first report message indicates a measurement result of one of said at least first and second reference signals received at the first device via the repeater node; after transmitting said at least first and second reference signals to the repeater node, receiving (s612) a second report message from a second device, wherein the second report message indicates a measurement result of one of said at least first and second reference signals received at the second device via the repeater node; based on the measurement results, determining (s614), for the D2D communication, an operation mode and / or a configuration of the repeater node; and transmitting (s616), to the repeater node, repeater configuration information indicating the determined operation mode and / or the determined configuration of the repeater node.

2. The method of claim 1, wherein the first side of the repeater node is configured to establish a control / backhaul link with the network node, the first side of the repeater node is capable of establishing an access link with a device, and the second side of the repeater node is capable of establishing an access link with a device.

3. The method of claim 1 or 2, wherein said at least first reference signal is received at the first device via the first side of the repeater node and said at least second reference signal is received at the second device via the first side of the repeater node,said at least first reference signal is received at the first device via the first side of the repeater node and said at least second reference signal is received at the second device via the second side of the repeater node, said at least first reference signal is received at the first device via the second side of the repeater node and said at least second reference signal is received at the second device via the first side of the repeater node, or said at least first reference signal is received at the first device via the second side of the repeater node and said at least second reference signal is received at the second device via the second side of the repeater node.

4. The method of any one of claims 1-3, wherein each of the first and second configurations indicates one or more of:I) one or more forwarding directions for forwarding one or more reference signals from the first side of the repeater node, ii) one or more forwarding directions for forwarding one or more reference signals from the second side of the repeater node, ii) one or more transmit, TX, beams of the first side of the repeater node to use for forwarding one or more reference signals, iv) one or more TX beams of the second side of the repeater node to use for forwarding one or more reference signals, and / or v) one or more timings at which the first or second configuration is to be applied to the repeater node and / or one or more time intervals during which the first or second configuration is to be applied to the repeater node.

5. The method of claim 4, wherein transmitting the first configuration information to the repeater node comprises transmitting, to the repeater node, a first configuration message indicating the first configuration, transmitting the second configuration information to the repeater node comprises transmitting, to the repeater node, a second configuration message indicating the second configuration, the first configuration message comprises a flag value indicating that the first configuration is for configuring the first side of the repeater node, and the second configuration message comprises a flag value indicating that the second configuration is for configuring the second side of the repeater node.

6. The method of any one of claims 1-5, wherein the first report message indicates quality of reference signals received at the first device via a plurality of TX beams at the first side of the repeater node and the second report message indicates quality of reference signals received at the second device via the plurality of TX beams at the first side of the repeater node,the first report message indicates quality of reference signals received at the first device via the plurality of TX beams at the first side of the repeater node and the second report message indicates quality of reference signals received at the second device via a plurality of TX beams at the second side of the repeater node, the first report message indicates quality of reference signals received at the first device via the plurality of TX beams at the second side of the repeater node and the second report message indicates quality of reference signals received at the second device via the plurality of TX beams at the first side of the repeater node, or the first report message indicates quality of reference signals received at the first device via the plurality of TX beams at the second side of the repeater node and the second report message indicates quality of reference signals received at the second device via the plurality of TX beams at the second side of the repeater node.

7. The method of any one of claims 1-6, wherein the first report message indicates a first TX beam at the first side of the repeater node, which is in the direction of the first device and the second report message indicates a second TX beam at the first side of the repeater node, which is in the direction of the second device, the first report message indicates the first TX beam at the first side of the repeater node, which is in the direction of the first device and the second report message indicates a third TX beam at the second side of the repeater node, which is in the direction of the second device, the first report message indicates a fourth TX beam at the second side of the repeater node, which is in the direction of the first device and the second report message indicates the second TX beam at the first side of the repeater node, which is in the direction of the second device, or the first report message indicates the fourth TX beam at the second side of the repeater node, which is in the direction of the first device and the second report message indicates the third TX beam at the second side of the repeater node, which is in the direction of the second device.

8. The method of any one of claims 1-7, wherein the operation mode of the repeater node is any one of:(i) receiving one or more signals at the first side of the repeater node and forwarding the received one or more signals from the second side of the repeater node;(ii) receiving one or more signals at the first side of the repeater node and forwarding the received one or more signals from the first side of the repeater node;(ill) receiving one or more signals at the second side of the repeater node and forwarding the received one or more signals from the first side of the repeater node;(iv) receiving one or more signals at the second side of the repeater node and forwarding the received one or more signals from the second side of the repeater node.

9. The method of claim 8 when claim 8 depends on claim 2, whereinIn the operation mode (II), a transmitter and / or a receiver for providing the access link at the second side is configured to be off while a transmitter and / or a receiver for providing the access link at the first side is configured to be on, and in the operation mode (iv), the transmitter and / or the receiver for providing the access link at the first side is configured to be off while the transmitter and / or tje receiver for providing the access link at the second side is configured to be on.

10. The method of any one of claims 1-9, wherein the configuration of the repeater node indicates: a first beam to use at the first side of the repeater node for the D2D communication for the first device and a second beam to use at the first side of the repeater node for the D2D communication for the second device, the first beam to use at the first side of the repeater node for the D2D communication for the first device and a third beam to use at the second side of the repeater node for the D2D communication for the second device, a fourth beam to use at the second side of the repeater node for the D2D communication for the first device and the second beam to use at the first side of the repeater node for the D2D communication for the second device, or the fourth beam to use at the second side of the repeater node for the D2D communication for the first device and the third beam to use at the second side of the repeater node for the D2D communication for the second device.11 . The method of claim 9, wherein the repeater configuration information includes one or more of: a beam identifier, ID, (e.g., a beam index) identifying the first beam or the fourth beam; a beam ID identifying the second beam or the third beam; a beam type ID identifying a type of the first beam or the fourth beam; a beam type ID identifying a type of the second beam or the third beam; a beam polarization ID identifying a polarization of the first beam or the fourth beam; and / or a beam polarization ID identifying a polarization of the second beam or the third beam.

12. The method of any one of claims 1-10, the method further comprising obtaining capability information about the repeater node, wherein the capability information indicates one or more of: a number of beams and / or a type of beams available at the first side of the repeater node; a number of beams and / or a type of beams available at the second side of the repeater node; how quickly the repeater node can switch its beams at the first side; how quickly the repeater node can switch its beams at the second side;how quickly the repeater node can decode beam setting related control information; power control capability of the repeater node at the first side; power control capability of the repeater node at the second side; on / off capability of the repeater node at the first side; on / off capability of the repeater node at the second side; antenna configurations at the first side of the repeater node; and / or antenna configurations at the second side of the repeater node.

13. The method of claim 12, wherein the capability information indicates a type of the repeater node at the first side and / or a type of the repeater node at the second side, the type of the repeater node at the first side is selected from a group consisting of wide-area, WA, medium range, MR, and local-area, LA, and the type of the repeater node at the second side is selected from a group consisting of WA and LA.

14. The method of any one of claims 1-13, wherein the repeater node is either a network-controlled repeater, NCR, or an intelligent reflective surface, IRS.

15. A method (700) for establishing a device-to-device, D2D, communication via a repeater node (114), the method being performed by the repeater node, the method comprising: receiving (s702), from a network node (102), first configuration information which indicates a first configuration for configuring a first side of the repeater node to forward at least first reference signal that the repeater node receives from the network node; receiving (s704), from the network node, second configuration information which indicates a second configuration for configuring a second side of the repeater node to forward at least second reference signal that the repeater node receives from the network node; after receiving the first configuration information from the network node, receiving (s706) said at least first reference signal from the network node; after receiving the second configuration information from the network node, receiving (s708) said at least second reference signal from the network node; forwarding or reflecting (s710) said at least first reference signal from the first side of the repeater node; forwarding or reflecting (s712) said at least second reference signal from the second side of the repeater node; andreceiving (s714), from the network node, repeater configuration information indicating an operation mode and / or a configuration of the repeater node for the D2D communication.

16. The method of claim 15, wherein the first side of the repeater node is configured to establish a control / backhaul link with the network node, the first side of the repeater node is capable of establishing an access link with a device, and the second side of the repeater node is capable of establishing an access link with a device.

17. The method of claim 15 or 16, wherein each of the first and second configurations indicates one or more of:I) one or more forwarding directions for forwarding one or more reference signals from the first side of the repeater node, ii) one or more forwarding directions for forwarding one or more reference signals from the second side of the repeater node, ii) one or more transmit, TX, beams of the first side of the repeater node to use for forwarding one or more reference signals, iv) one or more TX beams of the second side of the repeater node to use for forwarding one or more reference signals, and / or v) one or more timings at which the first or second configuration is to be applied to the repeater node and / or one or more time intervals during which the first or second configuration is to be applied to the repeater node.

18. The method of any one of claims 15-17, wherein receiving the first configuration information from the network node comprises receiving, from the network node, a first configuration message indicating the first configuration, receiving the second configuration information from the network node comprises receiving, from the network node, a second configuration message indicating the second configuration, the first configuration message comprises a flag value indicating that the first configuration is for configuring the first side of the repeater node, and the second configuration message comprises a flag value indicating that the second configuration is for configuring the second side of the repeater node.

19. The method of any one of claims 15-18, wherein the operation mode of the repeater node is any one of: (i) receiving one or more signals at the first side of the repeater node and forwarding the received one or more signals from the second side of the repeater node;(ii) receiving one or more signals at the first side of the repeater node and forwarding the received one or more signals from the first side of the repeater node;(ill) receiving one or more signals at the second side of the repeater node and forwarding the received one or more signals from the first side of the repeater node; or(iv) receiving one or more signals at the second side of the repeater node and forwarding the received one or more signals from the second side of the repeater node.

20. The method of claim 19, wherein in the operation mode (ii), a transmitter and / or a receiver for providing the link of the second side is configured to be off, and in the operation mode (iv), a transmitter and / or a receiver for providing the link of the first side is configured to be off.

21. The method of any one of claims 15-20, wherein the D2D communication is between a first device and a second device, and the configuration of the repeater node indicates: a first beam to use at the first side of the repeater node for the D2D communication for the first device and a second beam to use at the first side of the repeater node for the D2D communication for the second device, the first beam to use at the first side of the repeater node for the D2D communication for the first device and a third beam to use at the second side of the repeater node for the D2D communication for the second device, a fourth beam to use at the second side of the repeater node for the D2D communication for the first device and the second beam to use at the first side of the repeater node for the D2D communication for the second device, or the fourth beam to use at the second side of the repeater node for the D2D communication for the first device and the third beam to use at the second side of the repeater node for the D2D communication for the second device.

22. The method of claim 21, wherein the repeater configuration information includes one or more of: a beam identifier, ID, (e.g., a beam index) identifying the first beam or the fourth beam; a beam ID identifying the second beam or the third beam; a beam type ID identifying a type of the first beam or the fourth beam; a beam type ID identifying a type of the second beam or the third beam;a beam polarization ID identifying a polarization of the first beam or the fourth beam; and / or a beam polarization ID identifying a polarization of the second beam or the third beam.

23. The method of any one of claims 15-22, the method further comprising transmitting, to the network node, capability information about the repeater node, wherein the capability information indicates one or more of: a number of beams and / or a type of beams available at the first side of the repeater node; a number of beams and / or a type of beams available at the second side of the repeater node; how quickly the repeater node can switch its beams at the first side; how quickly the repeater node can switch its beams at the second side; how quickly the repeater node can decode beam setting related control information; power control capability of the repeater node at the first side; power control capability of the repeater node at the second side; on / off capability of the repeater node at the first side; on / off capability of the repeater node at the second side; antenna configurations at the first side of the repeater node; and / or antenna configurations at the second side of the repeater node.

24. The method of claim 23, wherein the capability information indicates a type of the repeater node at the first side and / or a type of the repeater node at the second side, the type of the repeater node at the first side is selected from a group consisting of wide-area, WA, medium range, MR, and local-area, LA, and the type of the repeater node at the second side is selected from a group consisting of WA and LA.

25. The method of any one of claims 15-24, wherein the repeater node is either a network-controlled repeater, NCR, or an intelligent reflective surface, IRS.

26. A computer program (800 or 900) comprising instructions (844 or 944) which when executed by processing circuitry (802 or 902) cause the processing circuitry to perform the method of any one of claims 1-25.

27. A carrier containing the computer program of claim 26, wherein the carrier is one of an electronic signal, an optical signal, a radio signal, and a computer readable storage medium.

28. A network node (102) for establishing a device-to-device, D2D, communication via a repeater node (114), the network node being configured to: transmit (s602), to the repeater node, first configuration information which indicates a first configuration for configuring a first side of the repeater node to forward at least first reference signal that the repeater node receives from the network node; transmit (s604), to the repeater node, second configuration information which indicates a second configuration for configuring a second side of the repeater node to forward at least second reference signal that the repeater node receives from the network node; after transmitting the first configuration information to the repeater node, transmit (s606) said at least first reference signal to the repeater node; after transmitting the second configuration information to the repeater node, transmit (s608) said at least second reference signal to the repeater node; after transmitting said at least first and second reference signals to the repeater node, receive (s610) a first report message from a first device, wherein the first report message indicates a measurement result of one of said at least first and second reference signals received at the first device via the repeater node; after transmitting said at least first and second reference signals to the repeater node, receive (s612) a second report message from a second device, wherein the second report message indicates a measurement result of one of said at least first and second reference signals received at the second device via the repeater node; based on the measurement results, determine (s614), for the D2D communication, an operation mode and / or a configuration of the repeater node; and transmit (s616), to the repeater node, repeater configuration information indicating the determined operation mode and / or the determined configuration of the repeater node.

29. The network node of claim 28, wherein the network node is further configured to perform the method of any one of claims 2-14.

30. A repeater node (114) for establishing a device-to-device, D2D, communication via the repeater node, the repeater node being configured to: receive (s702), from a network node (102), first configuration information which indicates a first configuration for configuring a first side of the repeater node to forward at least first reference signal that the repeater node receives from the network node; receive (s704), from the network node, second configuration information which indicates a second configuration for configuring a second side of the repeater node to forward at least second reference signal that the repeater node receives from the network node;after receiving the first configuration information from the network node, receive (s706) said at least first reference signal from the network node; after receiving the second configuration information from the network node, receive (s708) said at least second reference signal from the network node; forward or reflect (s710) said at least first reference signal from the first side of the repeater node; forward or reflect (s712) said at least second reference signal from the second side of the repeater node; and receive (s714), from the network node, repeater configuration information indicating an operation mode and / or a configuration of the repeater node for the D2D communication.31 . The repeater node of claim 30, wherein the repeater node is further configured to perform the method of any one of claims 16-25.

32. An apparatus (800 or 900) comprising: a processing circuitry (802 or 902); and a memory (841 or 941), said memory containing instructions executable by said processing circuitry, whereby the apparatus is operative to perform the method of any one of claims 1-25.

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