WO2025040235A1

WO2025040235A1 - Sidelink communication control based on relaxed measurement mode

Info

Publication number: WO2025040235A1
Application number: PCT/EP2023/072808
Authority: WO
Inventors: Santhan THANGARASA; Muhammad Ali Kazmi; Min Wang
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 2023-08-18
Filing date: 2023-08-18
Publication date: 2025-02-27
Anticipated expiration: 2026-02-18

Abstract

A wireless device (10) obtains information whether the wireless device (10) itself or a further wireless device operates in a relaxed measurement mode of a cellular interface. Based on the obtained information, the wireless device (10) controls sidelink communication of the wireless device (10) and the further wireless device (10).

Description

Sidelink communication control based on relaxed measurement mode

Technical Field

The present invention relates to methods for controlling wireless communication in a wireless communication network and to corresponding devices, systems, and computer programs.

Background

In wireless communication networks, e.g., based on the 4G (4th Generation) LTE (Long Term Evolution) or 5G (5th Generation) NR technology as specified by 3GPP (3rd Generation Partnership Project), it is known to provide support for direct device-to-device (D2D) communication in addition to downlink (DL) and uplink (UL) communication via a cellular interface. For example, the LTE technology and the NR technology support sidelink (SL) communication between wireless devices, typically denoted as UE (user equipment). In the LTE technology and NR technology the radio interface for SL communication is also denoted as “PC5” (or “LTE PC5” and “NR PC5”, respectively), while the cellular radio interface for DL and UL communication is also denoted as “Uu” (or “LTE Uu” and “NR Uu”, respectively). Examples of use cases and applications of D2D communication, or more specifically SL communication, include V2V (vehicle-to-vehicle) communication, V2X (vehicle-to-anything) communication, and various kinds of proximity services (ProSe). Further use cases include UE-to-UE (U2U) relay and UE-to-network (U2N) relay.

As compared to LTE SL, NR SL has been in enhanced in various ways. For example, while LTE SL supports only broadcast communication, NR SL is capable of broadcast, groupcast, and unicast communication. In groupcast communication, the intended receivers of a message are typically a subset of the vehicles near the transmitter, whereas in unicast communication, there is a single intended receiver. Broadcast, groupcast, and unicast transmissions for V2X communication on SL are supported for the in-coverage, out-of- coverage and partial-coverage scenarios. For unicast and groupcast transmissions on SL, HARQ (Hybrid Automatic Repeat Request) feedback and HARQ combining in the physical layer of the UE are supported. Both LTE SL and NR SL can operate with and without network coverage and with varying degrees of interaction between the UEs and the network, including support for standalone, network-less operation.

SL communication can be configured on a dedicated carrier, e.g., a carrier of an ITS (Intelligent Transport Systems) band or a carrier of the serving cell of the UE. In the latter case the SL resources and resources for cellular communication, i.e., DL/LIL, may be shared in time and/or frequency. Typically, the SL resources are time multiplexed with the uplink resources used for cellular communication on the serving cell of the UE.

For improving power efficiency, 3GPP Release 17 includes features enabling relaxed measurements by the UE. For example, 3GPP TS 36.304 V17.4.0 (2023-03) and 3GPP TS 38.304 V17.5.0 (2023-06) specify relaxed monitoring criteria or relaxed measurement criteria: In RRC (Radio Resource Control) idle state or RRC inactive state, the UE can be configured to perform neighbor cell measurements, e.g. for cell reselection, in a relaxed manner, when the UE meets one or more corresponding criteria, herein also denoted as RMC. Here, it is noted that such RMC can correspond to a relaxed monitoring criterion of the LTE technology, e.g., as specified in 3GPP TS 36.304 V17.4.0 or to a relaxed measurement criterion of the NR technology, e.g., as specified in 3GPP TS V17.5.0. The UE can be configured with respect to the application of one or more RMCs via higher layer signaling, e.g., based on configurations provided on in system information block (SIB) such as in SIB2. Examples of RMCs are: UE in low mobility, UE not-at-cell-edge, stationary, combined criterion (e.g. UE in low mobility and not-at-cell-edge, stationary and not-at-cell-edge).

Further, relaxed measurement criteria for a radio link procedure (RLP) are specified in 3GPP TS 36.331 V17.5.0. (2023-06) and in 3GPP TS 38.331 V17.5.0 (2023-06). Examples of RLP are RLM (Radio Link Management), BFD (Beam Failure Detection), CBD (Candidate Beam Detection), measurement of L1-RSRP (Layer 1 Reference Signal Received Power), measurement of L1-SINR (Layer 1 Signal to Noise Ratio), or the like. An example of a relaxed measurement criterion for the RLP is good serving cell quality: For example, when the UE meets the good serving cell quality criterion for a RLP then the UE is allowed to relax one or more measurements for that RLP, e.g., RLM or BFD. Examples of measurements for RLM are radio link quality estimation for OOS (out of sync) evaluation/detection, radio link quality estimation for IS (in sync) evaluation/detection etc. Examples of measurement for BFD is radio link quality estimation for BFD evaluation/detection, or the like.

If one or more RMCs are fulfilled, the UE is allowed to relax one or more neighbor cell measurements, e.g., intra-frequency measurements, inter-frequency and/or inter-RAT measurements. With such relaxation, the neighbor cell measurements are performed under relaxed, i.e., less strict, requirements. For example, the measurement time of a relaxed measurement (RM) may be longer than the measurement time of the corresponding normal measurement (NM), i.e., when the measurement is not relaxed. In many scenarios, a SL UE can operate both using the SL interface and the cellular interface. Further, such UE could be configured with power saving functionalities on the cellular interface, such as measurement relaxation. However, usage of such power saving functionality on the cellular interface could adversely affect SL operation of the UE. For example, if the UE operates as a U2N relay UE for a remote UE, the power saving functionality on the cellular interface could result in a reduced performance in forwarding data from the remote UE to the network and/or a reduced performance in receiving data to be forwarded to the remote UE from the network. Similar problems may also occur due to shared usage of hardware, e.g., receiver and transmitter hardware, for SL interface and cellular interface.

Accordingly, there is a need for techniques which allow for more efficiently controlling SL operation of a wireless device.

Summary

According to an embodiment, a method of controlling wireless communication is provided. According to the method, a wireless device obtains information whether a further wireless device operates in a relaxed measurement mode of a cellular interface of the further wireless device. Based on the obtained information, the wireless device controls SL communication of the wireless device and the further wireless device.

According to a further embodiment, a method of controlling wireless communication is provided. According to the method, a wireless device obtains information whether the wireless device operates in a relaxed measurement mode of a cellular interface of the wireless device. Based on the obtained information, the wireless device controls SL communication of the wireless device and a further wireless device.

According to a further embodiment, a wireless device for operation in a wireless communication network is provided. The wireless device is configured to obtain information whether a further wireless device operates in a relaxed measurement mode of a cellular interface of the further wireless device. Further, the wireless device is configured to, based on the obtained information, control SL communication of the wireless device and the further wireless device.

According to a further embodiment, a wireless device for operation in a wireless communication network is provided. The wireless device comprises at least one processor and a memory. The memory contains instructions executable by said at least one processor, whereby the wireless device is operative to obtain information whether a further wireless device operates in a relaxed measurement mode of a cellular interface of the further wireless device. Further, the memory contains instructions executable by said at least one processor, whereby the wireless device is operative to, based on the obtained information, control SL communication of the wireless device and the further wireless device.

According to a further embodiment, a wireless device for operation in a wireless communication network is provided. The wireless device is configured to obtain information whether the wireless device operates in a relaxed measurement mode of a cellular interface of the wireless device. Further, the wireless device is configured to, based on the obtained information, control SL communication of the wireless device and a further wireless device.

According to a further embodiment, a wireless device for operation in a wireless communication network is provided. The wireless device comprises at least one processor and a memory. The memory contains instructions executable by said at least one processor, whereby the wireless device is operative to obtain information whether the wireless device operates in a relaxed measurement mode of a cellular interface of the wireless device. Further, the memory contains instructions executable by said at least one processor, whereby the wireless device is, based on the obtained information, control SL communication of the wireless device and a further wireless device.

According to a further embodiment of the invention, a computer program or computer program product is provided, e.g., in the form of a non-transitory storage medium, which comprises program code to be executed by at least one processor of a wireless device. Execution of the program code causes the wireless device to obtain information whether a further wireless device operates in a relaxed measurement mode of a cellular interface of the further wireless device. Further, execution of the program code causes the wireless device to, based on the obtained information, control SL communication of the wireless device and the further wireless device.

According to a further embodiment of the invention, a computer program or computer program product is provided, e.g., in the form of a non-transitory storage medium, which comprises program code to be executed by at least one processor of a wireless device. Execution of the program code causes the wireless device to obtain information whether the wireless device operates in a relaxed measurement mode of a cellular interface of the wireless device. Further, execution of the program code causes the wireless device to, based on the obtained information, control SL communication of the wireless device and a further wireless device.

Details of such embodiments and further embodiments will be apparent from the following detailed description of embodiments.

Brief Description of the Drawings

Fig. 1 schematically illustrates a wireless communication network according to an embodiment of the present disclosure.

Fig. 2 schematically illustrates a U2N relay scenario according to an embodiment of the present disclosure.

Fig. 3 schematically illustrates carrier adaptation of SL aggregation according to an embodiment of the present disclosure.

Fig. 4 schematically illustrates adaptation of SL reference signal transmission according to an embodiment of the present disclosure.

Fig. 5 schematically illustrates a relay selection according to an embodiment of the present disclosure.

Fig. 6 schematically illustrates signaling according to an embodiment of the present disclosure.

Fig. 7 shows a flowchart for schematically illustrating a method according to an embodiment.

Fig. 8 shows a flowchart for schematically illustrating a further method according to an embodiment.

Fig. 9 schematically illustrates structures of a wireless device according to an embodiment.

Fig. 10 schematically illustrates interaction of a host and a wireless device according to an embodiment. Detailed Description

In the following, concepts in accordance with exemplary embodiments of the invention will be explained in more detail and with reference to the accompanying drawings. The illustrated embodiments relate to controlling SL communication in a wireless communication network. The wireless communication network may be based on the 5G NR technology specified by 3GPP. However, other technologies could be used as well, e.g., the 4G LTE technology specified by 3GPP or a future 6G (6^th Generation) technology.

In the present disclosure, the term “node” may refer to a network node or to a UE. Examples of network nodes are radio network node, NodeB, base station (BS), multistandard radio (MSR) radio node such as MSR BS, eNodeB (eNB), gNodeB (gNB), MeNB, SeNB, integrated access backhaul (IAB) node, network controller, radio network controller (RNC), base station controller (BSC), relay node, donor node controlling relay, base transceiver station (BTS), Central Unit (CU), e.g., in a gNB, Distributed Unit (DU), e.g., in a gNB, Baseband Unit, Centralized Baseband, C-RAN, access point (AP), transmission point (TP), transmission node, Remote Radio Unit (RRU), Remote Radio Head (RRH), distributed antenna system (DAS) node, core network node, e.g., MSC (Mobile Switching Center), MME etc., O&M (Operations and Management) node, OSS (Operation Support System) node, SON (Self Organized Network) node, positioning node, e.g., an E-SMLC (Evolved Serving Mobile Location Center), or the like.

Another example of a node is a UE, may refer to various types of wireless device communicating with a network node and/or with another wireless device in a cellular or mobile communication system. Examples of UE are target device, device to device (D2D) UE, vehicular to vehicular (V2V), machine type communication (MTC) UE or UE capable of machine to machine (M2M) communication, PDA (Personal Digital assistant), tablet, mobile terminal, smart phone, laptop embedded equipment (LEE), laptop mounted equipment (LME), USB dongle, or the like.

The term radio access technology (RAT) may refer to various types of RAT, e.g., the LTE RAT, a narrow band internet of things (NB-loT) RAT, WiFi, Bluetooth, a next generation RAT, the NR RAT, a 4G ART, a 5G RAT, or the like. Any of the equipment denoted by the terms node, network node, or radio network node may be capable of supporting a single or multiple RATs. The term “signal” may refer to various types of physical signal or physical channel. Examples of physical signals are reference signals (RSs) such as PSS (Primary Synchronization Signal), SSS (Secondary Synchronization Signal), CSI-RS (Channel State Information Reference Signal), DMRS (Demodulation Reference Signal), an SSB (Synchronization Signal Block) or signal of an SSB, CRS (cell-specific reference signal), PRS (positioning reference signal), SRS (sounding reference signal), or the like. A physical channel may carry layer information, e.g., one or more logical channels, one or more transport channels, or the like. Examples of physical channels are MIB (Master Information Block), PSBCH (Physical SL Broadcast Channel), PSCCH (Physical SL Control Channel), PSSCH (Physical SL Shared Channel), PBCH (Physical Broadcast Channel), PDCCH (Physical DL Control Channel), PDSCH (Physical DL Shared Channel), PLICCH (Physical UL Control Channel), PLISCH (Physical UL Shared Channel), or the like.

The term “time resource” may refer to various types of physical resource or radio resource defined in terms of length of time. Examples of time resources are: symbol, time slot, subframe, radio frame, TTI (Transmission Time Interval), interleaving time, or the like. A TTI may correspond to any time period over which a physical channel can be encoded and optionally interleaved for transmission. The physical channel may be decoded by the receiver over the same time period over which it was encoded. The TTI may also interchangeably be denoted as short TTI (sTTI), transmission time, slot, sub-slot, mini-slot, mini-subframe or the like.

The term “time-frequency resource” may refer to various types of physical resource or radio resource defined in a time-frequency resource grid, e.g., for a given cell. Examples of timefrequency resources are resource block (RB), carrier, subcarrier, or the like. A RB be a physical RB (PRB) or a virtual RB (VRB).

The term “wireless access network (WAN)” may various types of to radio network involving communication between a UE and a network node, e.g., base station. The signals transmitted between the UE and the network node are herein also denoted as WAN signals. The signal transmitted by the UE to the network node may be denoted as UL WAN signal. The signal transmitted by the network node to the UE may be denoted as DL WAN signal. The WAN may also interchangeably be denoted as cellular network, radio access network (RAN), Uu interface, cellular interface, radio network interface, or the like. The corresponding link or radio link over which the WAN signals are transmitted may also be denoted as WAN link, RAN link, Uu link, uplink (UL) - for transmission from UE to network node, downlink (DL) - for transmission from network node to UE, forward link (network to UE), reverse link (network to UE) or the like. Therefore, a WAN link can also be WAN UL or UL WAN or WAN DL or DL WAN. The corresponding signals transmitted between the UE and the network node, may also interchangeably be denoted as cellular signals, Uu signals, RAN signals or the like. The WAN signals may belong to or operate in any type of RAT, e.g., the LTE RAT or NR RAT. In the following, the terms WAN communication, WAN link, and WAN signal are used in a generic manner.

A link or radio link over which signals are transmitted between at least two UEs for D2D communication is herein also denoted as sidelink (SL). The signals transmitted between the UEs for D2D communication are also denoted as SL signals. The SL may also interchangeably be denoted as D2D link, V2X link, ProSe link, peer-to-peer link, PC5 link, or the like. The SL signals may also interchangeably be denoted as V2X signals, D2D signals, ProSe signals, PC5 signals, peer-to-peer signals, or the like.

The term “in coverage (IC)” may refer to a scenario in which the UE is under full coverage of one or more network nodes, e.g., serving cells. For example, if the UE can detect at least one cell, then it may be considered as IC. In another example, if the UE can detect at least one cell on a carrier on which it is configured to perform SL communication, the UE may be considered as IC. In another example, if the UE detects at least one cell on the frequency on which the UE is configured to perform SL communication and fulfils a cellselection criterion denoted as “S criterion”, the UE may consider itself to be IC for SL communication operation on that frequency. If the UE is IC, it is able to receive signals from and/or transmit signals to at least one network node. The UE can then also maintain a communication link with the network. The term “IC” may also interchangeably be used with “In Network Coverage (INC)”.

The term out of coverage (OOC) may refer to a scenario in which none of the UEs involved in SL communication is under network coverage. In another example, OOC may refer to a situation in which the UE is not associated with a serving cell on any carrier. In another example, if the UE cannot detect any cell then it may consider itself to be OOC. If the UE is configured to perform SL communication on a frequency and cannot detect any cell on that frequency which meets the S criterion, then the UE may consider itself to be OOC for SL communication on that frequency. In another example, if the UE cannot detect any cell on any carrier on which it is configured to perform SL communication, the UE may consider itself to be OOC. The term “OOC” may also be interchangeably used with “Out-Of-Network Coverage (ONC)”, “Any Cell Selection state”, or the like. The term “partial coverage (PC)” may refer to a scenario in which at least one of the UEs among the UEs involved in SL communication is under the network coverage, is IC, and at least one other UE involved in the SL communication is not under network coverage, i.e. , is OOC. The term “PC” may also interchangeably be used with “Partial Network Coverage (PNC)”.

The term “sidelink synchronization reference signal (SLRS)” may refer to various kinds of signal that may be used for synchronization in SL communication, e.g.: SL-SSB, SLSS (SL Synchronization Signal), S-PSS (SL Primary Synchronization Signal), S-SSS (SL Secondary Synchronization Signal), PSBCH, or any combination of such signals, e.g., S- SS and PSBCH, or S-SS and S-PSS and PSBCH.

It is noted that the illustrated concepts are applicable various types of D2D communication, including ProSe, V2X, or the like.

Examples of physical channels and reference signals for SL communication in NR or LTE are:

PSSCH (Physical Sidelink Shared Channel, SL version of PDSCH): The PSSCH is transmitted by a sidelink transmitter UE, which conveys sidelink transmission data, system information blocks (SIBs) for radio resource control (RRC) configuration, and a part of the sidelink control information (SCI).

PSFCH (Physical Sidelink feedback channel): The PSFCH is transmitted by a sidelink receiver UE for unicast and groupcast, which conveys 1 bit information over 1 RB for the HARQ acknowledgement (ACK) and the negative ACK (NACK). In addition, channel state information (CSI) is carried in the medium access control (MAC) control element (CE) over the PSSCH instead of the PSFCH.

PSCCH (Physical Sidelink Common Control Channel, SL version of PDCCH): When the traffic to be sent to a receiver UE arrives at a transmitter UE, a transmitter UE should first send the PSCCH, which conveys a part of SCI (Sidelink Control information, SL version of DCI) to be decoded by any UE for the channel sensing purpose, including the reserved timefrequency resources for transmissions, demodulation reference signal (DM RS) pattern and antenna port, etc.

Sidelink Primary/Secondary Synchronization Signal (S-PSS/S-SSS): Similar to downlink transmissions in NR, in sidelink transmissions, primary and secondary synchronization signals (called S-PSS and S-SSS, respectively) are supported. Through detecting the S-PSS and S-SSS, a UE is able to identify the sidelink synchronization identity (SSID) from the UE sending the S-PSS/S-SSS. Through detecting the S-PSS/S-SSS, a UE is therefore able to know the characteristics of the UE transmitter the S-PSS/S-SSS. A series of process of acquiring timing and frequency synchronization together with SSIDs of UEs is called initial cell search. Note that the UE sending the S-PSS/S-SSS may not be necessarily involved in sidelink transmissions, and a node (UE/eNB/gNB) sending the S-PSS/S-SSS is called a synchronization source. There are 2 S-PSS sequences and 336 S-SSS sequences forming a total of 672 SSIDs in a cell.

Physical Sidelink Broadcast Channel (PSBCH): The PSBCH is transmitted along with the S-PSS/S-SSS as a synchronization signal/PSBCH block (SSB). The SSB has the same numerology as PSCCH/PSSCH on that carrier, and an SSB should be transmitted within the bandwidth of the configured BWP. The PSBCH conveys information related to synchronization, such as the direct frame number (DFN), indication of the slot and symbol level time resources for sidelink transmissions, in-coverage indicator, etc. The SSB is transmitted periodicly at every 160 ms.

DMRS, phase tracking reference signal (PT-RS), channel state information reference signal (CSI-RS): These physical reference signals supported by NR downlink/uplink transmissions are also adopted by sidelink transmissions. Similarly, the PT-RS is only applicable for FR2 transmission.

The SL communication of the illustrated concepts may be based on resource allocation as specified for LTE SL and NR SL, in particular on the following two modes of resource allocations:

Mode 1: SL resources are scheduled by a gNB.

Mode 2: The UE autonomously selects SL resources from a (pre-)configured SL resource pool(s) based on a channel sensing mechanism.

For a UE which is IC, Mode 1 or Mode 2 can be used. For a UE which is OOC, typically only Mode 2 is available.

In the illustrated concepts, a UE may control SL communication with another UE depending on whether the UE itself or the other UE is in a relaxed measurement mode of a cellular interface of the UE. This may for example be applied in a relay scenario in which a first UE (UE1) acts as a relay for a second UE (UE2), to enable communication of the second UE with a cell (Celli). In such scenario, the first UE may also be denoted as relay UE and the second UE as remote UE. In such scenario, UE1 and UE2 each have a respective SL interface enabling the SL communication. Further, at least UE1 has a cellular interface which enables WAN communication with Celli (or one or more other cells). In such scenario, UE1 may determine information whether UE1 is operating in the relaxed measurement mode of its cellular interface, which is used for communication with Celli or one or more other cells. Depending on this information, UE1 may perform one or more operational tasks related to the SL communication with UE2. Such operational tasks performed by UE1 may include:

- adapting transmission of SLRS, e.g., SLSS, on its SL interface. For example, transmitting SLRS with a periodicity Trs which is longer than a reference periodicity Tr when UE1 is in the relaxed measurement mode of its cellular interface; otherwise transmitting the SLRS with any periodicity, e.g., a periodicity which is shorter than the reference periodicity Tr.

- adapting one or more parameters related to carrier aggregation on its SL interface.

- informing other nodes, UE2 and/or potential other relay UEs about the adapted transmission of SLRS.

- informing other nodes, e.g., UE2 or potential other relay UEs about its usage of the relaxed measurement mode on the cellular interface, and/or

- informing other nodes, e.g., UE2 or potential other remote UEs, whether or not UE1 will continue to operate or be available as relay UE.

Alternatively or in addition, UE2 may determine information whether UE1 is operating in the relaxed measurement mode of its cellular interface, which is used for communication with Celli or one or more other cells. UE2 may receive this information from UE1 or determine this information autonomously. Depending on this information, UE2 may perform one or more operational tasks related to the SL communication with UE1. Such operational tasks performed by UE2 may include:

- triggering relay reselection, e.g., to select a third UE (UE3) to act as relay UE of UE2 with respect to Celli or with respect to some other cell (Cell2), and/or

- stopping, suspending, or restarting SL communication with UE1.

The determination whether UE1 is operating in the relaxed measurement mode of its cellular interface may be based on determining if one or more of the following conditions are met:

- UE1 is configured with one or more RMCs for performing measurements in the WAN and meets the one or more configured RMCs, and/or

- UE1 changes its WAN activity state from higher activity level to a lower activity level.

The WAN activity level of UE1 may be determined by one or more of: RRC state, DRX cycle, extended DRX cycle, or the like. For example, UE1 may be determined to be in the relaxed measurement mode if at least one of the following conditions is met: - UE1 changes its RRC state from high activity RRC state to low activity RRC state,

- UE1 operates with DRX cycle longer than a reference DRX cycle, and/or

- UE1 operates with an extended DRX cycle or with an extended DRX cycle longer than threshold.

Fig. 1 illustrates exemplary structures of the wireless communication network. In particular, Fig. 1 shows UEs 10 which are served by access nodes 100 of the wireless communication network. Here, it is noted that the wireless communication network may actually include a plurality of access nodes 100 that may serve a number of cells within the coverage area of the wireless communication network.

The access nodes 100 may be regarded as being part of an RAN of the wireless communication network. Further, Fig. 1 schematically illustrates a CN (Core Network) 210 of the wireless communication network. In Fig. 1 , the CN 210 is illustrated as including a GW (gateway) 220 and one or more control node(s) 240. The GW 220 may be responsible for handling user plane data traffic of the UEs 10, e.g., by forwarding user plane data traffic from a UE 10 to a network destination or by forwarding user plane data traffic from a network source to a UE 10. Here, the network destination may correspond to another UE 10, to an internal node of the wireless communication network, or to an external node which is connected to the wireless communication network. Similarly, the network source may correspond to another UE 10, to an internal node of the wireless communication network, or to an external node which is connected to the wireless communication network. The GW 220 may for example correspond to a UPF (User Plane Function) of the 5G Core (EGC) or to an SGW (Serving Gateway) or PGW (Packet Data Gateway) of the 4G EPC (Evolved Packet Core). The control node(s) 240 may for example be used for controlling the user data traffic, e.g., by providing control data to the access node 100, the GW 220, and/or to the UE 10.

As illustrated by solid double-headed arrows, the access nodes 100 may send DL wireless transmissions to at least some of the UEs 10, and some of the UEs 10 may send UL wireless transmissions to the access node 100. Further, as illustrated by broken double-headed arrows, some of the UEs 10 may perform SL transmissions.

The DL transmissions, UL transmissions, and/or SL transmissions may be used to provide various kinds of services to the UEs 10, e.g., a voice service, a multimedia service, or some other data service. Such services may be hosted in the CN 210, e.g., by a corresponding network node. By way of example, Fig. 1 illustrates an application service platform 250 provided in the CN 210. Further, such services may be hosted externally, e.g., by an AF (application function) connected to the CN 210. By way of example, Fig. 1 illustrates one or more application servers 300 connected to the CN 210. The application server(s) 300 could for example connect through the Internet or some other wide area communication network to the CN 210. The application service platform 250 may be based on a server or a cloud computing system and be hosted by one or more host computers. Similarly, the application server(s) 300 may be based on a server or a cloud computing system and be hosted by one or more host computers. The application server(s) 300 may include or be associated with one or more AFs that enable interaction with the CN 210 to provide one or more services to the UEs 10, corresponding to one or more applications. These services or applications may generate the user data traffic conveyed by the DL transmissions, the UL transmissions, and/or the SL transmissions. Accordingly, the application server(s) 300 may include or correspond to the above-mentioned network destination and/or network source for the user data traffic. In the respective UE 10, such service may be based on an application (or shortly “app”) which is executed on the UE 10. Such application may be pre-installed or installed by the user. Such application may generate at least a part of the user plane data traffic between the UEs 10 and the access node 100.

In accordance with the illustrated concepts, usage of a relaxed measurement mode of the cellular interface of one or more of the UEs 10 may be considered when controlling SL communication of this UE 10, e.g., SL communication as illustrate by the broken doubleheaded arrows in Fig. 1. This SL communication may for example be used for implementing U2N relaying. However, it is noted that similar principles could also be applied in other use cases of SL communication, including also OOC scenarios. For example, in an OOC scenario, two UEs 10 could engage in SL communication, and at least one of these UEs 10 could be in the relaxed measurement mode of its cellular interface, e.g., because it is stationary. This information may then be considered when controlling the SL communication between the UEs 10.

Fig. 2 illustrates an exemplary scenario involving U2N relaying, in which the illustrated concepts may be applied. The scenario involves a network node 100, e.g., corresponding to one of the access nodes 100 of Fig. 1, a first UE 10, denoted as UE1, and a second UE, denoted as UE2. UE1 is within coverage of a cell, denoted as Celli, served by the network node. In the illustrated example, it is assumed that Celli is the serving cell of UE1. WAN communication (or cellular communication) is based on a Uu link between UE1 and the network node, using a cellular interface of UE1. SL communication between UE1 and UE2 is based on a PC5 link between UE1 and UE2, using respective SL interfaces of UE1 and UE2. The WAN communication in Celli is assumed to be based on a first carrier frequency (F1). The SL communication on the PC5 is assumed to be based on a second carrier frequency (F2). In some cases, F1 and F2 may be different. It is however also possible that F1 and F2 are the same. U2N relay operation in the scenario of Fig. 2 may involve that UE1 relays DL data transmitted by the network node and received by UE1 via the llu link to UE2, using the PC5 link. Further LIE2N operation in the scenario of Fig. 2 may involve that UE1 relays the UL data, received from UE2 via the PC5 link, to the network node, using the llu link.

The WAN communication of UE1 may further involve that UE1 operates one or more periodic WAN signals on WAN resources. This may be on F1, but could in some cases also be on other carrier frequencies, e.g., in the context of inter-frequency procedures. The term operating a signal by UE1 may involve one or more of: transmitting a signal to another node (e.g., serving cell, neighbor cell, UE2, or the like) and receiving a signal from another node (e.g., serving cell, neighbor cell, UE2, or the like). Periodic WAN signals are signals which occur with certain periodicity. Each periodic occurrence of the WAN signal may be referred to as signal occasion, signal operational occasion, signal operational opportunity, signal duration or the like. The WAN signal transmission occasion may be used by UE1 for transmitting WAN signals e.g. in the UL. The WAN signal reception occasion may be used by UE1 for receiving the WAN signals, e.g., in the DL. Examples of period WAN signals that are used in performing Uu operational tasks, such as. RLM, BFD, CBD, RRM measurement, are SSB, CSI-RS, signals within SMTC etc. Example of periodic SL signals that are used by other SL UEs for synchronization purpose are SL SLSS or SL CSI-RS.

In the illustrated scenario, it is further assumed that UE1 is configured with one or more rules or criteria associated with usage of the relaxed measurement mode on its cellular interface, such criteria may for example correspond to one or more RMCs, e.g., as specified in 3GPP TS 36.304 V17.4.0 or 3GPP TS 38-304 V17.5.0. Examples of such criteria may include:

- signal quality of the serving cell falling below certain threshold;

- signal strength of the serving cell falling below certain threshold;

- information associated with radio link problems, e.g., whether OOS indications have been detected, RLM timer is running, BLER below certain threshold, or the like;

- mobility of the UE, e.g., whether the UE is in stationary or low mobility state, location of the UE with respect to the cell center, or the like.

By way of example, an RMC for low mobility UE may be fulfilled when the UE speed is below a certain threshold. The UE speed can be expressed in terms of distance per unit time and/or in Doppler frequency. In one specific example the relaxed measurement criterion for a UE with low mobility is fulfilled if the UE is stationary or static or does not move. In another example, the RMC for a UE with low mobility may be fulfilled when the received signal level at the UE with respect to a cell, e.g., serving cell, is static or quasi-static over certain time period. The received signal from the cell may be regarded as static or quasi-static if it does not change by more than certain margin over a certain time period, e.g., the variance of the measured signal levels is within a certain threshold. Examples of received signal are signal strength, path loss, RSRP (Reference Signal Received Power), L1-RSRP, L1-SINR, or the like.

In a specific example an RMC for UE with low mobility may be fulfilled when the following condition is met for the serving cell of the UE:

(SrxlevRef - Srxlev) < SSearchDeltaP. where:

Srxlev is the current Srxlev value of the serving cell (in dB), and

SrxlevRef is a reference Srxlev value of the serving cell (in dB).

After selecting or reselecting a new cell, or if (Srxlev - SrxlevRef) > 0, or if the relaxed measurement criterion has not been met for a duration of TsearchDeitap, the UE may set the value of SrxlevRef to the current Srxlev value of the serving cell.

Srxlev may be further defined as follows:

Srxlev — Qrxlevmeas — (Qrxlevmin + Qrxlevminoffset) — P compensation — Qoffsettemp, where:

Srxlev: It is is the cell selection received (RX) level value (in dB)

Qrxlevmeas: It is the measured cell RX level value (RSRP)

Qrxievmm is the minimum required RX level in the cell (in dBm). It is signaled by the cell.

Qrxlevminoffset is the offset to the signalled Qrxievmin. It is signaled by the cell.

Qoffsettemp: It is the offset temporarily applied to a cell. It is signaled by the cell.

An RMC for stationary UE may be defined in a way similar to UE with low mobility, but the actual values for the thresholds for stationary UE might be different compared to those used for the low mobility RMC. For example, the UE may meet the stationary UE RMC if the received signal from a cell, e.g. the serving cell, does not change by more than certain margin Hs over certain time period Ts. On the other hand the UE may meets the low mobility UE RMC if the received signal from the the cell does not change by more than certain margin Hm over a certain time period T m. Here, the absolute value of the margin Hs may be smaller than the absolute value of the margin Hm and/or the time period Ts may be longer than the time period Tm. In another example, the absolute value of the margin Hs may be equal to the absolute value of the margin Hm and/or the time period Ts may be longer than the time period Tm. In still another example the absolute value of the margin Hs may be smaller than the absolute value of the margin Hm and/or the time period Ts may be equal to the time period Tm.

An RMC for UE not at cell edge may be fulfilled when the received signal level at the UE from a cell, e.g., the serving cell, is above a threshold. For example, this may involve that signal strength is above a signal strength threshold and/or signal quality is above a signal quality threshold. In a specific example, an RMC for UE not at cell edge may be fulfilled when the following condition is met for the serving cell of the UE:

SrxleV > SsearchThreshoIdP, and,

Squal > SsearchThresholdQ, if SsearchThresholdQ is Configured, where:

Srxlev is the current Srxlev value of the serving cell (in dB), and Squal is the current Squal value of the serving cell (in dB).

Squal may be further defined as follows:

Squal — Qqualmeas ^— (Qqualmin + Qqualminoffset) " Qoffsettemp, where:

Squal is a cell selection quality value (in dB).

Qquaimeas is the measured cell quality level value (in terms of RSRQ).

Qquaimm is the minimum required quality level in the cell (in dB). It is signalled by the cell.

Qqualminoffset is the offset to the signaled Qquaimin. It is signaled by the cell.

The UE can be configured with multiple versions of UE not at cell edge RMC, e.g., Rel-16 UE not-at-cell edge, Rel-17 UE not-at-cell edge. In such case, the actual values for thresholds might be different because the purpose would be to identify the UEs located at different ranges with respect to the cell center.

When one or more RMCs are met, the UE may be allowed to relax measurements, i.e., to perform the measurements in a relaxed manner. This is herein also denoted as operation in the relaxed measurement mode. This measurement relaxation may be realized by meeting relaxed measurement requirements. For example, the UE may be allowed to meet one or more relaxed measurement requirements for performing a measurement provided that it is configured with an IE (Information Element) denoted as “lowMobilityEvaluation” and also meets a low mobility UE RMC, e.g., as defined above. In another example, the UE is allowed to meet one or more relaxed measurement requirements for performing a measurement provided that it is configured with an IE denoted as “cellEdgeEvaluation” and also meets a UE not at cell edge RMC, e.g., as defined above. In another example, the UE is allowed to meet one or more relaxed measurement requirements for performing a measurement provided that it is configured with an IE denoted as “combineRelaxedMeasCondition” and also meets the low mobility UE RMC and the UE not at cell edge RMC, e.g., as defined above. The lEs “lowMobilityEvaluation”, “cellEdgeEvaluation” and “combineRelaxedMeasCondition” are defined in 3GPP TS 38.331 V17.5.0.

If one or more RMCs are fulfilled, the UE may be allowed to relax one or more neighbor cell measurements, e.g., intra-frequency measurements, inter-frequency and/or inter-RAT measurements. With such relaxation, the neighbor cell measurements are performed under relaxed, i.e., less strict, requirements. Examples of such requirements are measurement time, measurement accuracy, measurement reporting periodicity, number of cells measured over measurement time, or the like. Examples of measurement time are cell identification time or cell detection time, evaluation period or measurement period (e.g., L1 measurement period, L1-RSRP measurement period, L1-SINR measurement period, OOS evaluation period, IS evaluation period, BFD evaluation period, BFD evaluation period, L1 indication interval, IS indication interval, OOS indication interval, BFD indication interval), or the like. Examples of measurement accuracy are L1-RSRP accuracy, L1-SINR accuracy. For example, the measurement time of a relaxed measurement (RM) may be longer than the measurement time of the corresponding normal measurement (NM), i.e., when the measurement is not relaxed. In an example, the measurement time for RM (T_meas_RM) is a function of T_meas_NM and a scaling factor K. Examples of functions are maximum, sum, product, ceiling, floor, or the like. For example, T_meas_RM could be defined as T_meas_RM = K*Tmeas_NM, where K > 1.

Accordingly, in some examples measurement relaxation may be achieved by extending the measurement time compared to the measurement time when no relaxation is applied. In another example measurement relaxation may be achieved by not performing any neighbor cell measurements. In still another example, measurement relaxation may be achieved by not performing any neighbor cell measurements for a certain time period, which may be predefined or configured by the network. Examples of measurement time in a low RRC activity state, e.g., in RRC idle state or RRC inactive state, include cell detection time (Tdetect) measurement period (Tmeasure), evaluation time (T_evaiuate), or the like. For example, when the UE is configured with lowMobilityEvaluation and also meets the low mobility UE criterion, the UE could perform intra-frequency neighbour cell measurements by applying a scaling factor of K=3 to the intra-frequency cell detection time Tdetect,NR_mtra, to the intra-frequency cell measurement period Tmeasure.NRjntra, and to the intra-frequency cell evaluation time Tevaiuate,NR_mtra. Otherwise, when no measurement relaxation is applied, these measurement times would be applied without scaling (or with a scaling factor of K=1).

Accordingly, upon meeting at least one of the configured criteria, e.g., at least one RMC as explained above, UE1 is allowed to operate one or more procedures in the relaxed measurement mode. Examples of procedures operated in relaxed measurement mode include:

- Radio Link Procedure (RLP) in the serving cell. Examples of such RLP are:

- radio link monitoring,

- link recovery procedure (LRP) or beam management procedure. Examples of the LRP include: BFD, CBD, beam signal measurement, e.g., L1-RSRP, L1-SINR, or the like;

- RRM measurement. Examples of RRM measurements are:

- serving cell measurements, e.g., RSRP, RSRQ, SINR, or the like,

- neighbor cell measurements, e.g., cell search, RSRP, RSRQ, SINR, RS index acquisition (e.g., SSB index acquisition) or the like.

The neighbor cell measurements may be performed on one or more carrier frequencies, e.g., intra-frequency carrier frequency, non-serving carrier frequency (including interfrequency carrier and inter-RAT carrier).

In some scenarios, UE1 may operate WAN operational tasks in low activity state, e.g., in RRC idle state or RRC inactive state, with long DRX cycle, or in extended DRX (eDRX). Alternatively, UE1 could operate WAN operational tasks in high activity state, e.g., in RRC connected state and/or with short DRX cycle. UE1 may also switch between low activity state and high activity state on WAN while operating as the relay UE of UE2.

In some implementations, UE1 may perform the following operations to control SL communication: Initially, UE1 may determine whether UE1 is operating or is expected to operate in the relaxed measurement mode of its cellular interface, e.g., with respect to its serving cell or one or more neighbor cells. If this is not the case, UE1 can be assumed to operate in a non-relaxed mode, which may also be referred to as a normal mode, baseline mode, or reference mode. Then, based on this determination, UE1 may perform one or more operational tasks related to the SL communication. To determine whether UE1 is operating or is expected to operate in the relaxed measurement mode of its cellular interface, UE1 may check whether one or more of the following conditions are met:

1. UE1 meets at least one RMC: For example, UE1 is configured by a network node with one or more RMCs for performing measurements on one or more cells in WAN and meets at least one of the configured RMC.

2. UE1 operates in low activity state: For example, if UE1 changes its WAN activity state from higher activity level to a lower activity level then it operates in the low activity state. UETs WAN activity level may be determined by one or more of: RRC state, DRX cycle, eDRX cycle, or the like. For example, UE1 may be assumed to be in relaxed measurement state if at least one of the following conditions is met:

- UE1 changes its RRC state from higher activity RRC state to lower activity RRC state. Examples of low activity state are RRC idle state, RRC inactive state, or the like. In another example, UE1 in RRC idle state has lower activity level than in RRC inactive state. Example of high activity state is RRC connected state.

- UE1 operates with a DRX cycle whose length is longer than the length of a reference DRX cycle, for example, when UE1 is configured with long DRX cycle, e.g., DRX cycle length longer than a threshold, such as 320 ms or longer.

- UE1 operates with extended DRX cycle (eDRX) or with eDRX cycle longer than a threshold, for example, when UE1 is configured with an eDRX cycle whose length is longer than 40.96 s.

- UE1 is configured with an eDRX cycle which has paging transmission window (PTW) and is UE1 is configured with one or more DRX cycles during the PTW so that UE1 can receive paging during the PTW.

Related to the first condition above, UE1 may obtain information about at least one RMC, which UE1 may evaluate for performing one or more measurements on one or more neighbor cells and/or serving cell. In one example UE1 may obtain information about the RMC based on a message received from the network node, e.g., configuration via signaling such as via RRC, DCI (DL Control Information) or MAC (Medium Access Control) Control Element. For example, a set of RMCs may be pre-defined and UE1 may select one or more RMCs from the set of predefined RMCs based on identifiers of one or more RMCs received from the network node. For example, if UE1 is configured with an identifier for a first RMC (RMC1) which is related to a low mobility criterion, then UE1 evaluates the criterion associated with the low mobility. In another example, if UE1 is configured with an identifier for a second RMC (RMC2) which is related to a not-at-cell edge criterion, then UE1 evaluates the criterion associated with the not-at-cell edge criterion.

The obtained information about the configured RMC(s) may be associated with one or more carriers. In one example, UE1 may be configured with one or more RMC(s) which are applicable for all carriers configured for measurements, e.g., for mobility measurements. In another example, UE1 may be configured with one or more RMC(s) which are applicable for specific set of carriers configured for measurements for certain RAT, e.g., for mobility measurements on NR carriers, for mobility measurements on LTE carriers, or the like. In another example, UE1 may be configured with one or more RMC(s) which are applicable for specific set of carriers configured for measurements, e.g., for mobility measurements. In the last two examples, the configured RMC(s) may be linked or associated with information about the carriers, e.g., carrier frequency identifier, carrier frequency number, or the like. Examples of carrier frequency identifier or number are absolute frequency channel number (ARFCN) and NR absolute frequency channel number (NR-ARFCN). Examples of mobility measurements are measurements for cell change, e.g., cell selection, cell reselection, or RRC connection re-establishment.

UE1 further evaluates whether UE1 meets at least one configured RMC. For example, if UE1 is configured with a low mobility RMC (e.g. RMC1), UE1 may evaluates whether the low mobility RMC is met or not.

In one example, the low mobility RMC is met provided that the speed of UE1 speed is below certain threshold (S1) over a certain time period (D1); otherwise the low mobility RMC is not met. In another example, the low mobility RMC is met provided that the magnitude of the variation of the received signal level measured by UE1 in a cell, e.g., its serving cell, is below certain threshold (S2) over certain time period (D2); otherwise the low mobility RMC is not met. Examples of received signal level are received signal strength (RSS) or received signal quality (RSQ). RSQ may also be referred to as a radio link quality estimated by UE1 on a reference signal (RS), e.g., SSB or CSI-RS, transmitted by a cell, its serving cell. Examples of the received signal strength are path loss or RSRP. Examples of the received signal quality are SNR, SINR, or RSRQ. The threshold and/or the time period, e.g. S1 , S2, D1 and D2, can be pre-defined or configured by the network node.

In another example, the criterion associated with a second RMC (RMC2), e.g., not-at-cell- edge RMC, is evaluated based on the received signal level measured by the UE1 in a cell, e.g., in it serving cell. In one example, if the received signal level measured by UE1 is above a certain threshold (S3) over certain time period (D3), the not-at-cell-edge RMC is met by UE1 ; otherwise UE1 may be considered as being at the cell edge. The threshold and/or the time period, e.g., S3 and D3, can be pre-defined or configured by the network node.

In another example, the criterion associated with a third RMC (RMC3), e.g., good serving cell RMC for a certain RLP, is evaluated by UE1 based on the received signal level, e.g., RSS or RSQ, as measured by UE1 in a cell, e.g., in its serving cell. For example, the good serving cell quality RMC is met for a RLP if the DL radio link quality estimated by UE1 on the configured RS resource, e.g., RLM-RS resource, is evaluated to be better than certain threshold. In one example if the received signal level, e.g., serving cell’s RSQ, measured by UE1 is above a certain threshold (S4) over certain time period (D4), UE1 meets the good serving cell quality RMC; otherwise UE1 does not meet the good serving cell quality RMC. Examples of considered RLP are RLM, BFD, CBD, or the like. The threshold and/or the time period, e.g., S4 and D4, can be pre-defined or configured by the network node.

As mentioned above, depending on the information concerning the usage of the relaxed measurement mode in WAN, UE1 may then control the SL communication with UE2.

In some scenarios, controlling the SL communication based on the information concerning the usage of the relaxed measurement mode in WAN may involve control of carrier aggregation on the SL, e.g., by adaptation of one or more parameters related to SL CA. In the case of SL CA, UE1 may operate using at least two carriers for the SL communication with UE2. Fig. 3 schematically illustrates carriers 21 that may be used for SL CA. As illustrated, a plurality of carriers 21 may be available for SL CA, each carrier corresponding to a different carrier frequency (f). The carriers 21 may be from the same frequency band, e.g., Band 1 or Band 2, as illustrated in Fig. 3, or from different frequency bands. In the case of SL CA, two or more of the carriers 21 may be used in parallel, i.e., aggregated, in the SL communication between UE1 and UE2. Such aggregated carriers 21 may be adjacent or non-adjacent. Further, such aggregated carriers 21 may be from the same frequency band or from different frequency bands. Aggregation of carriers 21 from the same frequency band is also termed as intra-band carrier aggregation. Aggregation of carriers 21 from different frequency bands is also termed as inter-band carrier aggregation. Aggregation of adjacent carriers 21 is also termed as contiguous carrier aggregation. Aggregation of non-adjacent carriers 21 is also termed as non-contiguous carrier aggregation. The adaptation of one or more parameters related to SL CA may for example include enabling or disabling SL CA, i.e., switching from using SL CA with multiple aggregated carriers to operation using only a single carrier and vice versa. For example, if UE1 determines that it is operating in the relaxed measurement mode, it may decide to disable SL CA. When the UE1 is no longer operating in the relaxed measurement mode, it may decide to reenable the SL CA. If SL CA is disabled by UE1 , UE1 may further inform the network node, e.g., the serving gNB of UE1 , about the disabling of SL CA. In some cases, the determination whether SL CA needs to be disabled could also, at least in part, be done by the network node, e.g., the serving gNB of UE1. For example, UE1 could inform the network node about the need to disable SL CA, and the network node could then decide to reconfigure UE1 accordingly.

In addition or as an alternative, the adaptation of one or more parameters related to SL CA may include switching between different types of SL CA, e.g., between intra-band SL CA, inter-band SL CA, intra-band contiguous SL CA, or intra-band non-contiguous SL CA. For example, upon determining that it is operating in or is going to operate in the relaxed measurement mode, UE1 could decide to switch from operating using inter-band SL CA to intra-band SL CA. In another example, UE1 may decide to switch from operating using intra-band non-contiguous SL CA to intra-band contiguous SL CA. In both examples, switching would be toward a type of SL CA which may be implemented by using a single broadband receiver chain and thus consumes less power compared to the former type of SL CA, which typically requires usage of multiple independent receiver chains.

In addition or as an alternative, the adaptation of one or more parameters related to SL CA may include reducing or increasing the number of aggregated carriers. For example, if UE1 determines that it is operating in the relaxed measurement mode, it may decide to reduce the number of aggregated carriers from N1 to NT, where NT < N1. On the other hand, when UE1 is no longer operating in the relaxed measurement mode, UE1 may resume the SL CA operation using N1 number of carriers, increase the number of aggregated carriers.

In addition or as an alternative, the adaptation of one or more parameters related to SL CA may include updating, replacing, or reselecting carriers in the aggregated set of carriers. For example, one or more carriers with poor SL radio condition and/or high congestion could be replaced with one or more other carriers with better SL radio condition and/or lower congestion. After such change of carrier(s), UE1 may be able to use lower transmission power and/or fewer resources for SL transmissions towards UE2. In order to determine when to replace or update the aggregated carriers, a threshold may be configured or otherwise defined in UE1. Such threshold could for example be a SL radio quality threshold or congestion threshold.

In an example, a first SL RSRP threshold can be introduced for power saving purpose. A carrier (in the following denoted as carrier 1) is triggered to be replaced with another carrier (in the following denoted as carrier 2) whose radio quality is better than carrier 1 if the measured radio quality of carrier 1 (in terms of SL RSRP) is below the first SL RSRP threshold. A second SL RSRP threshold may be introduced for carrier 2, and carrier 2 may be selected to replace carrier 1 only when the radio quality of carrier 2 (in terms of SL RSRP) is found to be higher than the second threshold.

In a further example, an SL channel busy ratio (SL CBR) threshold can be introduced for power saving purpose. A carrier (in the following denoted as carrier 1) is triggered to be replaced with another carrier (in the following denoted as carrier 1) whose measured congestion is lower than that of carrier 1 if the measured congestion of carrier 1 (in terms of SL CBR) is higher than the first threshold. For example, a second SL CBR threshold may be introduced for carrier 2, and carrier 2 may be selected to replace carrier 1 only when the measured congestion of carrier 2 (in terms of SL CBR) is lower than the second threshold.

It is noted that in the above examples the adaptation of one or more parameters related to SL CA operation could also be performed by the network node, e.g., the serving gNB of UE1 , e.g., depending on the resource selection mode of SL operation. For example, in the case of mode 1 resource selection, the network node could send a modified SL CA configuration to UE1. As compared to that, in the case of mode 2 resource selection, UE1 could apply the adapted parameters related to SL CA in an autonomous manner. In another example, UE1 could be pre-configured by the network node with at least two configurations related to the SL CA, e.g., pre-configured with a first SL CA configuration (SL CA1) and a second SL CA configuration (SL CA2) or configured with a SL CA configuration and a single carrier operation SL configuration (non-CA SL configuration). In such case, UE1 could switches between SL CA1 and SL CA2 or between the SL CA configuration and the non-CA SL configuration when one or more conditions are met, e.g., conditions as described above. Examples of SL CA1 and SL CA2 could be: intra-band SL CA and inter-band SL CA respectively; intra-band contiguous CA and intra-band noncontiguous CA, respectively; SL CA with N1 aggregated carriers and SL CA with NT aggregated carriers, respectively (where N1’<N1). Further, it is noted that in the above examples of SL CA, the aggregated carriers may belong to the same serving cell or to different serving cells for the UE.

Having adapted the one or more parameters related to SL CA operation, UE1 may inform its SL peer UE, i.e. , UE2 in the illustrated example, accordingly. This may for example be done via PC5-RRC signaling, MAC CE, and/or L1 signaling, e.g., by SL Control Information (SCI). Based on such information, UE2 may then only monitor the carriers which are involved in the SL CA operation (as currently adapted).

In some scenarios, controlling the SL communication based on the information concerning the usage of the relaxed measurement mode in WAN may involve adaptation of transmission of SL reference signals (SLRS), e.g., SLSS or S-SSB. For example, when UE1 uses the relaxed measurement mode in WAN, UE1 may transmit the SLRS, e.g., SLSS or S-SSB, with a periodicity (Trs) which is longer than a reference periodicity (Tr); otherwise UE1 may transmit the SLRS with any periodicity, e.g., the reference periodicity Trs or a periodicity which is shorter than the reference periodicity Trs. This may avoid that UE1 needs to wake up from a sleep stat of the relaxed measurement mode only for the purpose of transmitting SLRS. As a result, power saving gain can be increased.

In an example, the adaptation of transmission of SLRS may involve that UE1 aligns the SLRS transmission periodicity to a measurement periodicity of the relaxed measurement mode. For example, if the requirements of the relaxed measurement mode specify that UE1 is required to measure on WAN signals every 160 ms, the SLRS periodicity could also be set to 160 ms. In another example, if UE1 is required to measure on the WAN signals every 640 ms, the SLRS periodicity could also be set to 640 ms. Fig. 4 illustrates a corresponding example.

Specifically, Fig. 4 illustrates two cases denoted as “case A” and “case B”. In case A, it is assumed that UE1 is operating in the non-relaxed measurement mode, and therefore a default SLRS transmission periodicity of 160 ms for SLRS transmission for UE2 is assumed. In case B, it is assumed that UE1 is operating in the relaxed measurement mode in WAN, and the SLRS transmission periodicity is accordingly, by extending the SLRS transmission periodicity from the default SLRS transmission periodicity of 160 ms to 320 ms.

Having adapted the transmission of SLRS, UE1 may inform its SL peer UE, i.e., UE2 in the illustrated example, and other nodes, other SL UEs and/or the network node accordingly. In one example, UE1 may inform other SL devices about the adapted transmission periodicity of SLRS, by broadcast, groupcast, or unicast of corresponding information. This information may enable the other SL UEs to operate according to the new adapted transmission of SLRS from UE1.

In some scenarios, one or more parameters related to the relaxed measurement mode could also be adapted. For example, similar to the previous example, the adaptation could involve that UE1 also adapts one or more parameters related to the relaxed mode in WAN based on the SLRS configuration. For example, if UE1 is required to measure on WAN signals every Tw, but SLRS on the SL is transmitted every Ts, where Ts>Tw, then Tw can be set to Ts. In a similar example, Tw could bet set to Tw=Ts+T1 , where T1 is a fixed or configurable offset. T1=0 may be regarded as a special case. Such adaptation could for example be achieved by adapting the above-mentioned relaxation factor K associated with WAN measurements to the SLRS configuration. In a further example, UE1 could adapt the WAN DRX configuration to the SLRS configuration to avoid that the UE has to wake up more frequently than the periodicity of SLRS.

In some scenarios, controlling the SL communication based on the information concerning the usage of the relaxed measurement mode in WAN may involve adaptation of one or more DRX configurations of the SL. For example, UE1 could reconfigure, request, or suggest a new SL DRX cycle configuration to other SL devices it is communicating with, e.g., for UE2. The new SL DRX cycle may depend on how often UE1 needs to wake up to operate on WAN signals. The new SL DRX cycle may enable that UE1 does not need to wake up more frequently for SL operation than required for operating the WAN signals.

UE1 may also inform other nodes, its SL peer UE (UE2), other SL UEs, including other (potential) SL relay UEs about its mode in WAN, in particular whether or not it uses the relaxed measurement mode. For example, UE1 could signals such information on the SL by PC5-RRC signaling, a MAC CE, or L1 signaling, e.g., SCI on PSCCH or PSSCH. Informs other nodes (e.g. SL remote UEs such as UE2) whether UE1 will continue to operate as SL relay UE or not.

In some scenarios, the UE2 could be configured with multiple modes of SL reception. Such configuration could for example be configured by UE1 or by the network node. UE2 could then determine which of the modes to apply for SL operation. The UE2 may indicate its preferred mode of SL reception to the UE1. The preferred mode of SL reception can be based on the information from UE1 concerning usage of the relaxed measurement mode in WAN. UE1 could then, optionally together with the network node, determine whether to adopt the preferred mode of SL reception for UE2. If the preferred mode of SL reception is adopted for UE2, UE1 may adjust its WAN operation to be aligned with the mode of SL reception applied by UE2.

In some scenarios, a new mode of operation or state of UE1 , e.g., after switching from a high activity state to low activity state, with respect to WAN operation of UE1 may not be suitable for continued operation of UE1 as relay UE. As a consequence, UE1 may decide to stop acting as a relay UE. UE1 may then accordingly inform other nodes, such as the remote UE(s) communicating with UE1 over a PC5 link, such as UE2, other (potential) relay UEs, or the network node.

In some scenarios, the mode of operation of a relay UE may be reconfigured with respect to the usage of the relaxed measurement mode. For example, if in the scenario of Fig. 2 the relay UE (UE1) has changed to a different mode, from the normal mode to the relaxed measurement mode in WAN mode or from the relaxed measurement mode in WAN to the normal mode, the relay UE could initiate configuration of the remote UE (UE2) to apply a corresponding mode of operation from the SL reception perspective. In other words, when the relay UE applies the relaxed measurement mode for the Uu monitoring or reception, the relay UE may configure the remote UE to apply a relaxed measurement mode for SL reception or monitoring with respect to the relay UE. When the relay UE applies the normal mode for Uu monitoring or reception, the relay UE may configure the remote UE to apply the normal node for SL reception or monitoring with respect to the relay UE.

In some scenarios, the network node could signal the configuration of the new mode with respect to the usage of the relaxed measurement mode to the relay UE, using signaling via the Uu interface. The signaling could be conveyed by RRC signaling, MAC CE, or L1 signaling, e.g., DCI on PDCCH.

While in the above examples UE1 considered the usage of the relaxed measurement mode on its own cellular interface when controlling SL communication with UE2, some scenarios could also involve that UE2 controls SL communication with UE1 based on information concerning usage of the relaxed measurement mode on the cellular interface of UE1. For this purpose, UE2 may receive information concerning the usage of the relaxed measurement mode on the cellular interface of UE1 from UE1 or could derive corresponding information from various indications received or otherwise available at UE2. In such scenarios, the remote UE (UE2) could thus first determine information concerning usage of the relaxed measurement mode on the cellular interface of the relay UE (UE1) and then, based on the determined information, performing one or more operational tasks related to SL communication with the relay UE.

The determination of the information concerning usage of the relaxed measurement mode on the cellular interface of the relay UE can be based on explicit information received from UE1 or from a third node indicating the mode of operation of UE1. In one example, it is assumed that UE1 informs UE2 about its mode of WAN operation, e.g., whether UE1 is operating in a power saving mode, whether UE1 applies a relaxed measurement mode, whether UE1 applies a longer DRX cycle, or eDRX cycle, whether UE1 is in RRC idle state or RRC inactive state. Alternatively or in addition UE1 could inform UE2 about change of its mode of WAN operation, e.g., whether the mode has changed between power saving mode and non-power saving mode, whether the mode has been changed between relaxed measurement mode and non-relaxed mode. UE2 may further determine the type of power saving mode in which UE1 is operating in WAN, e.g., due to RMC, due to being in eDRX, due to being RRC idle state, or due to being in RRC inactive state. Alternatively or in addition, UE2 could autonomously determine the mode of WAN operation of UE1 , e.g., whether the UE1 is operating in a power saving mode or relaxed measurement mode in WAN. This autonomous determination may be based information or indications transmitted by UE1. For example, if the UE1 has informed UE2 that UE1 has adapted its SLRS transmission, e.g., increased the SLRS periodicity from a short value to a large value, UE2 could infer that UE1 operates in a power saving mode, in particular the relaxed measurement mode in WAN. In another example, UE1 could have reconfigured one or more parameters related to activity state of UE2. For example, UE1 may have explicitly requested UE2 to operate in low activity state. In another example, UE1 may have requested UE2 to operate using a longer SL DRX cycle. Based on this type of indications, UE2 may infer that UE1 is operating in power saving mode with respect to its WAN operation, in particular in the relaxed measurement mode in WAN. As a further example, UE2 could infer that UE1 is operating in power saving mode with respect to its WAN operation, in particular in the relaxed measurement mode in WAN, if the periodic reference signals transmitted by the UE1 have a periodicity above a certain threshold (H1). Otherwise, UE2 may assume that UE1 is not operating in the relaxed measurement mode.

Based on the determined information concerning the usage of the relaxed measurement mode on the cellular interface of UE1 , UE2 then performs one or more operational tasks related to SL communication with the relay UE. Such tasks may for example include triggering reselection of the relay UE, i.e., to switch from using UE1 as the relay UE to using some other UE as the relay UE. This may also result in switching to another relay UE which has a different serving cell than UE1. Fig. 5 illustrates an example of a corresponding scenario. In the example of Fig. 5, it is assumed that first UE1 acts as the relay UE of UE2, with Celli being the serving cell of UE1. Then, based on being informed that UE1 has changed to the relaxed measurement mode on WAN, UE2 may decide to change to using another UE (UE3) as relay UE. After the relay reselection, UE3 acts as the relay UE of UE2, with Cell2 being the serving cell of UE3. For example, if UE1 is determined to be operating in the relaxed measurement mode in WAN for at least certain time duration T1 , then UE2 may trigger a SL relay reselection process towards UE3. The value of T1 can be predefined or configurable by a node, e.g., a network node or UE1. Alternatively, the value if T1 could be autonomously determined by UE2.

In a further example, the triggering of the SL relay reselection by UE2 could depend on the type of relaxed measurement mode applied by UE1. For example, if the UE1 is in the relaxed measurement mode with respect to neighbor cell measurements, UE2 could decide to refrain from triggering the SL relay reselection. However, if UE1 found to be in the relaxed measurement mode with respect to serving cell measurements, e.g., relaxed serving cell RRM measurements, relaxed RLP (such as relaxed RLM, relaxed BFD, o relaxed CBD), UE2 could decide to trigger the SL relay reselection. The new relay UE (in the illustrated example UE3) can be on the same carrier frequency or on a different carrier frequency as the carrier frequency (F2) used for SL communication with the previous relay UE.

In a further example, the triggering of the SL relay reselection by UE2 could depend on level of relaxation allowed in current state for UE1 , e.g., whether UE1 is operating in RRC connected mode, RRC idle mode, or whether UE1 is configured with extended DRX. Such different states may in turn result in different values of the above-mentioned relaxation factor K. In a specific example, UE2 could trigger the SL relay reselection if UE1 is operating in RRC idle state or RRC inactive state, but not trigger the SL relay reselection if UE1 is operating in RRC connected state.

In some scenarios, the one or more operational tasks performed by UE2 could include stopping, suspending, or restarting SL operation. For example, if UE2 determines that UE1 is operating in the relaxed measurement mode in WAN, UE2 could stop the SL operation. In one example UE2 could stop the SL operation with respect to UE1 only. In another example, UE2 could stop the SL operation with respect to any other UE (including UE1). For example, the stopping of the SL operation by UE2 may comprise one or more of the following: UE2 discarding the SL signals detected from another UE (e.g., UE1) and/or UE2 releasing a SL configuration used for the SL operation with respect to another UE (e.g., UE1). Further, UE2 could suspend the SL operation. In an example, UE2 could suspend the SL operation with respect to UE1 only. In another example, UE2 could suspend the SL operation with respect to any other UE (including UE1). The SL operation may remain suspended until a certain condition is met, e.g., until UE1 reverts to a normal mode of WAN operation, without usage of the relaxed measurement mode in WAN. Further, UE2 could postpone the use of UE1 as the relay UE for a period of time (T2). The value of T2 can be configurable or predefined. T2=0 may be regarded as a special case. The period of time for which use of UE1 as relay UE is suspended, stopped or postponed may further depend on the type of WAN operating mode used by UE1. Examples of type of WAN operating mode are: low activity state, high activity state, eDRX operation, relaxed measurement mode with respect to neighbor cells, relaxed measurement mode with respect to serving cells, or the like. UE2 may restart the use of UE1 as relay UE with one or more new SL configuration parameters. For example, the restart could be based on using SL-DRX on the SL for operation with respect to UE1. In another example, the restart could be based on using a SL-DRX cycle that is longer than a threshold with respect to UE1.

In some scenarios, the one or more operational tasks performed by UE2 could include control of carrier aggregation on the SL, e.g., by adaptation of one or more parameters related to SL CA. In the case of SL CA, UE2 may operate using at least two carriers for the SL communication with UE1.

The adaptation of one or more parameters related to SL CA may for example include enabling or disabling SL CA, i.e., switching from using SL CA with multiple aggregated carriers to operation using only a single carrier and vice versa. For example, if UE2 determines that UE1 is operating in the relaxed measurement mode in WAN, it may decide to disable SL CA. When UE1 is no longer operating in the relaxed measurement mode in WAN, UE1 may decide to reenable the SL CA. In some cases, the disabling or enabling of SL CA could also be based on negotiation or other interaction between UE2 and UE1.

In addition or as an alternative, the adaptation of one or more parameters related to SL CA may include switching between different types of SL CA, e.g., between intra-band SL CA, inter-band SL CA, intra-band contiguous SL CA, or intra-band non-contiguous SL CA. For example, upon determining that it is operating in or is going to operate in the relaxed measurement mode, UE2 could decide to switch from operating using inter-band SL CA to intra-band SL CA. In another example, UE2 may decide to switch from operating using intra-band non-contiguous SL CA to intra-band contiguous SL CA.

In addition or as an alternative, the adaptation of one or more parameters related to SL CA may include reducing or increasing the number of aggregated carriers. For example, if UE2 determines that UE1 is operating in the relaxed measurement mode in WAN, it may decide to reduce the number of aggregated carriers from N1 to NT, where NT < N1. On the other hand, when UE1 is no longer operating in the relaxed measurement mode in WAN, UE2 may resume the SL CA operation using N1 number of carriers, increase the number of aggregated carriers.

In addition or as an alternative, the adaptation of one or more parameters related to SL CA may include updating, replacing, or reselecting carriers in the aggregated set of carriers. For example, one or more carriers with poor SL radio condition and/or high congestion could be replaced with one or more other carriers with better SL radio condition and/or lower congestion. In order to determine when to replace or update the aggregated carriers, a threshold may be configured or otherwise defined in UE2. Such threshold could for example be a SL radio quality threshold or congestion threshold.

In a further example, an SL CBR threshold can be introduced for power saving purpose. A carrier (in the following denoted as carrier 1) is triggered to be replaced with another carrier (in the following denoted as carrier 1) whose measured congestion is lower than that of carrier 1 if the measured congestion of carrier 1 (in terms of SL CBR) is higher than the first threshold. For example, a second SL CBR threshold may be introduced for carrier 2, and carrier 2 may be selected to replace carrier 1 only when the measured congestion of carrier 2 (in terms of SL CBR) is lower than the second threshold.

In some scenarios, the one or more operational tasks performed by UE2 could include adaptation of transmission of SLRS, e.g., SLSS or S-SSB. For example, when UE1 uses the relaxed measurement mode in WAN, UE2 may transmit the SLRS, e.g., SLSS or S- SSB, with a periodicity (Trs) which is longer than a reference periodicity (Tr); otherwise UE2 may transmit the SLRS with any periodicity, e.g., the reference periodicity Trs or a periodicity which is shorter than the reference periodicity Trs. This may avoid that UE1 needs to wake up from a sleep stat of the relaxed measurement mode only for the purpose of receiving SLRS.

In an example, the adaptation of transmission of SLRS may involve that UE2 aligns the SLRS transmission periodicity to a measurement periodicity of the relaxed measurement mode. For example, if the requirements of the relaxed measurement mode specify that UE1 is required to measure on WAN signals every 160 ms, the SLRS periodicity could also be set to 160 ms. In another example, if UE1 is required to measure on the WAN signals every 640 ms, the SLRS periodicity could also be set to 640 ms, e.g., as illustrated in Fig. 4.

In some scenarios, the one or more operational tasks performed by UE2 could include adaptation of one or more DRX configurations of the SL. For example, UE2 could reconfigure, request, or suggest a new SL DRX cycle configuration for receiving signals from UE1. The new SL DRX cycle may depend on how often UE1 needs to wake up to operate on WAN signals. The new SL DRX cycle may enable that UE1 does not need to wake up more frequently for SL operation than required for operating the WAN signals.

Fig. 6 schematically illustrates an example of in accordance with the illustrated concepts. In the example of Fig. 6, it is assumed the UE1 and UE2 are already engaged in SL communication or are about to engage in SL communication. In an example, UE1 could act as relay UE for UE2, e.g., as U2N relay. At block 601 , UE1 enters the relaxed measurement mode in WAN. UE1 may indicate this change of its WAN operation by sending a relaxed measurement mode indication 602 to UE2. The relaxed measurement mode indication 602 may for example be conveyed by SL RRC signaling, by MAC CE, and/or by L1 signaling, e.g., SCI on PSCCH.

In accordance with the usage of the relaxed measurement mode in WAN, SL communication 603 between UE1 and UE2 is adapted. This may involve various kinds of decisions and/or adaptation by UE1 and/or UE2. As explained above, such adaptations may for example concern stopping, suspending, postponing, or restarting SL operation, control of SL CA, adaptation of SLRS transmission, control of SL DRX, and/or SL relay selection. Fig. 7 shows a flowchart for illustrating a method, which may be utilized for implementing the illustrated concepts. The method of Fig. 7 may be used for implementing the illustrated concepts in a wireless device. For example, such wireless device may correspond to any of the above-mentioned UEs 10. In some scenarios, the wireless device may use another wireless device as relay, e.g., such as explained for the above-mentioned remote UE.

If a processor-based implementation of the wireless device is used, at least some of the steps of the method of Fig. 7 may be performed and/or controlled by one or more processors of the wireless device. Such wireless device may also include a memory storing program code for implementing at least some of the below described functionalities or steps of the method of Fig. 7.

At step 710, the wireless device obtains information whether a further wireless device operates in a relaxed measurement mode of a cellular interface of the further wireless device.

In some scenarios, the wireless device may obtain the information by receiving an indication via an SL communication interface of the wireless device, e.g., from the further wireless device. The above-mentioned relaxed measurement mode indication 602 is an example of such indication. The indication may be conveyed by SL RRC signaling, by MAC CE, and/or by L1 signaling, e.g., SCI on PSCCH.

At step 720, the wireless device may select a relay node. This may be accomplished based on the information obtained at step 710. For example, this may involve selecting the further device as the relay node. In other cases, the further device may already act as relay node for the wireless device and step 720 may involve selecting another wireless device for the wireless device. Accordingly, in some scenarios the further wireless device relays data between the wireless device and a node of the wireless communication network. In such scenarios, selection of the further wireless device as a relay node, for relaying data between the wireless device and a node of the wireless communication network, may depends on the information obtained at step 710.

At step 730, the wireless device controls SL communication of the wireless device and the further wireless device. This is accomplished based on the information obtained at step 710. In some scenarios, step 730 may involve that, based on the obtained information, the wireless device controls carrier aggregation on an SL interface to the further wireless device. For example, enablement and/or disablement of carrier aggregation on the SL interface may depend on the obtained information. Alternatively or in addition, selection between carrier aggregation modes on the SL interface may depend on the obtained information. The carrier aggregation modes may include one or more of: intra-band carrier aggregation, inter-band carrier aggregation, intra-band contiguous carrier aggregation, and intra-band noncontiguous carrier aggregation. Alternatively or in addition, a number of carriers for carrier aggregation on the SL interface may depend on the obtained information. Alternatively or in addition, selection of carriers for carrier aggregation on the SL interface may depend on the obtained information. In some scenarios, the carrier aggregation on the SL interface could at least in part be configured based on signaling from a node of the wireless communication network. Alternatively or in addition, the carrier aggregation on the SL interface could at least in part be configured based on signaling from the further wireless device. For example, such signaling from the node of the wireless communication network and/or from the further wireless device could define one or more SL CA configurations which may be selected depending on the information obtained at step 710.

In some scenarios, step 730 may involve that, based on the obtained information, the wireless device controls transmission of reference signals on an SL interface to the further wireless device. For example, a transmission periodicity of the reference signals on the SL interface could depends on the obtained information. In some scenarios, the transmission of reference signals on the SL interface could at least in part be configured based on signaling from a node of the wireless communication network. Alternatively or in addition, the transmission of reference signals on the SL interface is at least in part configured based on signaling from the further wireless device. For example, such signaling from the node of the wireless communication network and/or from the further wireless device could define one or more SL reference signal configurations which may be selected depending on the information obtained at step 710.

In some scenarios, step 730 may involve that, based on the obtained information, the wireless device controls a DRX configuration of a sidelink interface to the further wireless device. In some scenarios, the DRX configuration of the SL interface could at least in part be configured based on signaling from a node of the wireless communication network. Alternatively or in addition, the DRX configuration of the SL interface could at least in part configured based on signaling from the further wireless device. For example, such signaling from the node of the wireless communication network and/or from the further wireless device could define one or more SL DRX configurations which may be selected depending on the information obtained at step 710.

Fig. 8 shows a flowchart for illustrating a further method, which may be utilized for implementing the illustrated concepts. The method of Fig. 8 may be used for implementing the illustrated concepts in a wireless device in a wireless device which also operates a cellular interface to a wireless communication network. For example, such wireless device may correspond to any of the above-mentioned UEs 10. In some scenarios, the wireless device may act as a relay for one or more other wireless devices, e.g., such as explained for the above-mentioned relay UE.

If a processor-based implementation of the wireless device is used, at least some of the steps of the method of Fig. 8 may be performed and/or controlled by one or more processors of the wireless device. Such wireless device may also include a memory storing program code for implementing at least some of the below described functionalities or steps of the method of Fig. 8.

At step 810, a wireless device obtains information whether the wireless device operates in a relaxed measurement mode of a cellular interface of the wireless device. The wireless device may obtain the information by determining based on one or more criteria whether the wireless device operates in the relaxed measurement mode of the cellular interface. Such criteria may for example include one or more RMCs. The one or more criteria may be or include at least one criterion configured by a node of the wireless communication network. The one or more criteria may include at least one criterion based on detecting activity of the wireless device on the cellular interface. The activity of the wireless device on the cellular interface may for example be detected based on RRC state of the cellular interface, e.g., whether the cellular interface is in RRC connected state, in RRC inactive state, or in RRC idle state. Alternatively or in addition, the activity of the wireless device on the cellular interface may be detected based on DRX configuration of the cellular interface.

At step 820, the wireless device may send, via an SL communication interface of the wireless device, an indication whether the wireless device operates in the relaxed measurement mode of the cellular interface. The wireless device may send the indication to the further wireless device. The above-mentioned relaxed measurement mode indication 602 is an example of such indication. The indication may be conveyed by SL RRC signaling, by MAC CE, and/or by L1 signaling, e.g., SCI on PSCCH. At step 830, the wireless device controls sidelink communication of the wireless device and a further wireless device. This is accomplished based on the information obtained at step 810.

In some scenarios, step 830 may involve that, based on the obtained information, the wireless device controls carrier aggregation on an SL interface to the further wireless device. For example, enablement and/or disablement of carrier aggregation on the SL interface may depend on the obtained information. Alternatively or in addition, selection between carrier aggregation modes on the SL interface may depend on the obtained information. The carrier aggregation modes may include one or more of: intra-band carrier aggregation, inter-band carrier aggregation, intra-band contiguous carrier aggregation, and intra-band noncontiguous carrier aggregation. Alternatively or in addition, a number of carriers for carrier aggregation on the SL interface may depend on the obtained information. Alternatively or in addition, selection of carriers for carrier aggregation on the SL interface may depend on the obtained information. In some scenarios, the carrier aggregation on the SL interface could at least in part be configured based on signaling from a node of the wireless communication network. Alternatively or in addition, the carrier aggregation on the SL interface could at least in part be configured based on signaling from the further wireless device. For example, such signaling from the node of the wireless communication network and/or from the further wireless device could define one or more SL CA configurations which may be selected depending on the information obtained at step 810.

In some scenarios, step 830 may involve that, based on the obtained information, the wireless device controls transmission of reference signals on an SL interface to the further wireless device. For example, a transmission periodicity of the reference signals on the SL interface could depends on the obtained information. In some scenarios, the transmission of reference signals on the SL interface could at least in part be configured based on signaling from a node of the wireless communication network. Alternatively or in addition, the transmission of reference signals on the SL interface is at least in part configured based on signaling from the further wireless device. For example, such signaling from the node of the wireless communication network and/or from the further wireless device could define one or more SL reference signal configurations which may be selected depending on the information obtained at step 810.

In some scenarios, step 830 may involve that, based on the obtained information, the wireless device controls a DRX configuration of a sidelink interface to the further wireless device. In some scenarios, the DRX configuration of the SL interface could at least in part be configured based on signaling from a node of the wireless communication network. Alternatively or in addition, the DRX configuration of the SL interface could at least in part configured based on signaling from the further wireless device. For example, such signaling from the node of the wireless communication network and/or from the further wireless device could define one or more SL DRX configurations which may be selected depending on the information obtained at step 810.

In some scenarios, the wireless device may, based on the SL communication with the further wireless device, relay data between the further wireless device and a node of the wireless communication network.

Fig. 9 illustrates a processor-based implementation of a wireless device 900 for operation in a wireless communication network, which may be used for implementing the abovedescribed concepts. More specifically, the structures of the wireless device 900 may be used to implement the above-described functionalities of UE1 , which may be a relay UE, or of UE2, which may be a remote UE.

As illustrated, the wireless device 900 may include an SL interface 910, which may be used for SL communication with one or more other wireless devices. The SL interface 910 could for example be based on the PC5 interface of the NR technology or the PC5 interface of the LTE technology. Further, the wireless device 900 may include a cellular interface 920, which may be used for WAN, in particular DL and/or UL, communication with one or more network nodes. The cellular interface 920 could for example be based on the Uu interface of the NR technology or the Uu interface of the LTE technology.

Further, the wireless device 900 may include one or more processors 950 coupled to the interface(s) 910, 920 and a memory 960 coupled to the processor(s) 950. By way of example, the interface(s) 910, 920 the processor(s) 950, and the memory 960 could be coupled by one or more internal bus systems of the wireless device 900. The memory 960 may include a read-only memory (ROM), e.g., a flash ROM, a random-access memory (RAM), e.g., a dynamic RAM (DRAM) or static RAM (SRAM), a mass storage, e.g., a hard disk or solid state disk, or the like. As illustrated, the memory 960 may include software 970 and/or firmware 980. The memory 960 may include suitably configured program code to be executed by the processor(s) 950 so as to implement or configure the above-described functionalities for controlling SL communication, such as explained in connection with Figs. 7 and 8. It is to be understood that the structures as illustrated in Fig. 9 are merely schematic and that the wireless device 900 may actually include further components which, for the sake of clarity, have not been illustrated, e.g., further interfaces or further processors. Also, it is to be understood that the memory 960 may include further program code for implementing known functionalities of a UE in a 3GPP system. According to some embodiments, also a computer program may be provided for implementing functionalities of the wireless device 900, e.g., in the form of a physical medium storing the program code and/or other data to be stored in the memory 960 or by making the program code available for download or by streaming.

Fig. 10 shows a communication diagram of a host 1002 communicating via a network node 1004 with a UE 1006 over a partially wireless connection in accordance with some embodiments. Example implementations, in accordance with various embodiments, of the UE (such as one of the above-mentioned UEs 10), network node (such as one of the above- mentioned access nodes 100), and host (such as the above-mentioned service platform 250 or application server(s) 300) will now be described with reference to Fig. 10.

Embodiments of host 1002 include hardware, such as a communication interface, processing circuitry, and memory. The host 1002 also includes software, which is stored in or accessible by the host 1002 and executable by the processing circuitry. The software includes a host application that may be operable to provide a service to a remote user, such as the UE 1006 connecting via an over-the-top (OTT) connection 1050 extending between the UE 1006 and host 1002. In providing the service to the remote user, a host application may provide user data which is transmitted using the OTT connection 1050.

The network node 1004 includes hardware enabling it to communicate with the host 1002 and UE 1006. The connection 1060 may be direct or pass through a core network (like core network 210 of Fig. 1) and/or one or more other intermediate networks, such as one or more public, private, or hosted networks. For example, an intermediate network may be a backbone network or the Internet.

The UE 1006 includes hardware and software, which is stored in or accessible by UE 1006 and executable by the UE’s processing circuitry. The software includes a client application, such as a web browser or operator-specific “app” that may be operable to provide a service to a human or non-human user via UE 1006 with the support of the host 1002. In the host 1002, an executing host application may communicate with the executing client application via the OTT connection 1050 terminating at the UE 1006 and host 1002. In providing the service to the user, the UE's client application may receive request data from the host's host application and provide user data in response to the request data. The OTT connection 1050 may transfer both the request data and the user data. The UE's client application may interact with the user to generate the user data that it provides to the host application through the OTT connection 1050.

The OTT connection 1050 may extend via a connection 1060 between the host 1002 and the network node 1004 and via a wireless connection 1070 between the network node 1004 and the UE 1006 to provide the connection between the host 1002 and the UE 1006. The connection 1060 and wireless connection 1070, over which the OTT connection 1050 may be provided, have been drawn abstractly to illustrate the communication between the host 1002 and the UE 1006 via the network node 1004, without explicit reference to any intermediary devices and the precise routing of messages via these devices. Here, it is noted that in the context of the present disclosure the OTT connection 1050 may also extend via a SL connection between two UEs, such as illustrated in the U2N relay scenario of Fig. 2.

As an example of transmitting data via the OTT connection 1050, in step 1008, the host 1002 provides user data, which may be performed by executing a host application. In some embodiments, the user data is associated with a particular human user interacting with the UE 1006. In other embodiments, the user data is associated with a UE 1006 that shares data with the host 1002 without explicit human interaction. In step 1010, the host 1002 initiates a transmission carrying the user data towards the UE 1006. The host 1002 may initiate the transmission responsive to a request transmitted by the UE 1006. The request may be caused by human interaction with the UE 1006 or by operation of the client application executing on the UE 1006. The transmission may pass via the network node 1004, in accordance with the teachings of the embodiments described throughout this disclosure. Accordingly, in step 1012, the network node 1004 transmits to the UE 1006 the user data that was carried in the transmission that the host 1002 initiated, in accordance with the teachings of the embodiments described throughout this disclosure. In step 1014, the UE 1006 receives the user data carried in the transmission, which may be performed by a client application executed on the UE 1006 associated with the host application executed by the host 1002.

In some examples, the UE 1006 executes a client application which provides user data to the host 1002. The user data may be provided in reaction or response to the data received from the host 1002. Accordingly, in step 1016, the UE 1006 may provide user data, which may be performed by executing the client application. In providing the user data, the client application may further consider user input received from the user via an input/output interface of the UE 1006. Regardless of the specific manner in which the user data was provided, the UE 1006 initiates, in step 1018, transmission of the user data towards the host 1002 via the network node 1004. In step 1020, in accordance with the teachings of the embodiments described throughout this disclosure, the network node 1004 receives user data from the UE 1006 and initiates transmission of the received user data towards the host 1002. In step 1022, the host 1002 receives the user data carried in the transmission initiated by the UE 1006.

The illustrated concepts may help to improve, performance of OTT services provided to the UE 1006 using the OTT connection 1050, in which the wireless connection 1070 forms a segment. More precisely, the teachings of these embodiments may allow for providing the wireless connection 1070, and thus also the OTT connection, in a power efficient manner taking into account the possibility that the UE 1006 could make use of the relaxed monitoring mode on its cellular interface, which implements the wireless connection 1070.

In an example scenario, factory status information may be collected and analyzed by the host 1002. As another example, the host 1002 may process audio and video data which may have been retrieved from a UE for use in creating maps. As another example, the host 1002 may collect and analyze real-time data to assist in controlling vehicle congestion (e.g., controlling traffic lights). As another example, the host 1002 may store surveillance video uploaded by a UE. As another example, the host 1002 may store or control access to media content such as video, audio, VR or AR which it can broadcast, multicast or unicast to UEs. As other examples, the host 1002 may be used for energy pricing, remote control of non-time critical electrical load to balance power generation needs, location services, presentation services (such as compiling diagrams etc. from data collected from remote devices), or any other function of collecting, retrieving, storing, analyzing and/or transmitting data.

In some examples, a measurement procedure may be provided for the purpose of monitoring data rate, latency, and other factors on which the one or more embodiments improve. There may further be an optional network functionality for reconfiguring the OTT connection 1050 between the host 1002 and UE 1006, in response to variations in the measurement results. The measurement procedure and/or the network functionality for reconfiguring the OTT connection may be implemented in software and hardware of the host 1002 and/or UE 1006. In some embodiments, sensors (not shown) may be deployed in or in association with other devices through which the OTT connection 1050 passes; the sensors may participate in the measurement procedure by supplying values of the monitored quantities exemplified above, or supplying values of other physical quantities from which software may compute or estimate the monitored quantities. The reconfiguring of the OTT connection 1050 may include message format, retransmission settings, preferred routing etc.; the reconfiguring need not directly alter the operation of the network node 1004. Such procedures and functionalities may be known and practiced in the art. In certain embodiments, measurements may involve proprietary UE signaling that facilitates measurements of throughput, propagation times, latency and the like, by the host 1002. The measurements may be implemented in that software causes messages to be transmitted, in particular empty or ‘dummy’ messages, using the OTT connection 1050 while monitoring propagation times, errors, etc.

As can be seen, the concepts as described above may be used for efficiently controlling SL operation of wireless devices. Specifically, the usage of power saving functionalities, in particular of a relaxed measurement mode, on a cellular interface of at least one of the SL UEs may be taken into account. As a result, effectiveness of such power saving functionalities may be improved and/or adverse effects on the SL communication avoided.

It is to be understood that the examples and embodiments as explained above are merely illustrative and susceptible to various modifications. For example, the illustrated concepts may be applied in connection with various kinds of wireless communication technologies. Moreover, it is to be understood that the above concepts may be implemented by using correspondingly designed software to be executed by one or more processors of an existing device or apparatus, or by using dedicated device hardware. Further, it should be noted that the illustrated apparatuses or devices may each be implemented as a single device or as a system of multiple interacting devices or modules.

Claims

1. A method of controlling wireless communication in a wireless communication network, the method comprising: a wireless device (10; 900; 1006) obtaining information whether a further wireless device (10; 900; 1006) operates in a relaxed measurement mode of a cellular interface (920) of the further wireless device (10; 900; 1006), and based on the obtained information, the wireless device (10; 900; 1006) controlling sidelink communication of the wireless device (10; 900; 1006) and the further wireless device (10; 900; 1006).

2. The method according to claim 2, wherein the wireless device (10; 900; 1006) obtains the information by receiving an indication (602) via a sidelink communication interface (910) of the wireless device (10; 900; 1006).

3. The method according to claim 1 or 2, wherein carrier aggregation on a sidelink interface (91 '0) to the further wireless device (10; 900; 1006) is controlled based on the obtained information.

4. The method according to claim 3, wherein enablement of carrier aggregation on the sidelink interface (910) depends on the obtained information.

5. The method according to claim 3 or 4, wherein disablement of carrier aggregation on the sidelink interface (910) depends on the obtained information.

6. The method according to any of claims 3 to 5, wherein selection between carrier aggregation modes on the sidelink interface (910) depends on the obtained information.

7. The method according to claim 6, wherein the carrier aggregation modes comprise one or more of: intra-band carrier aggregation, inter-band carrier aggregation, intra-band contiguous carrier aggregation, and intra-band non-contiguous carrier aggregation.

8. The method according to any of claims 3 to 7, wherein a number of carriers for carrier aggregation on the sidelink interface (910) depends on the obtained information.

9. The method according to any of claims 3 to 8, wherein selection of carriers for carrier aggregation on the sidelink interface (910) depends on the obtained information.

10. The method according to any of claims 3 to 9, wherein the carrier aggregation on the sidelink interface (910) is at least in part configured based on signaling from a node (100; 1004) of the wireless communication network.

11. The method according to any of claims 3 to 10, wherein the carrier aggregation on the sidelink interface (910) is at least in part configured based on signaling from the further wireless device (10; 900; 1006).

12. The method according to any of the preceding claims, wherein transmission of reference signals on a sidelink interface (910) to the further wireless device is controlled based on the obtained information.

13. The method according to claim 12, wherein a transmission periodicity of the reference signals on the sidelink interface (910) depends on the obtained information.

14. The method according to claim 12 or 13, wherein the transmission of reference signals on the sidelink interface (910) is at least in part configured based on signaling from a node (100; 1004) of the wireless communication network.

15. The method according to any of claims 12 to 14, wherein the transmission of reference signals on the sidelink interface (910) is at least in part configured based on signaling from the further wireless device (10; 900; 1006).

16. The method according to any of the preceding claims, wherein a discontinuous reception, DRX, configuration of a sidelink interface (910) to the further wireless device (10; 900; 1006) is controlled based on the obtained information.

17. The method according to claim 16, wherein the DRX configuration of the sidelink interface (910) is at least in part configured based on signaling from a node (100; 1004) of the wireless communication network.

18. The method according to claim 16 or 17, wherein the DRX configuration of the sidelink interface (910) is at least in part configured based on signaling from the further wireless device (10; 900; 1006).

19. The method according to any of the preceding claims, wherein the further wireless device (10; 900; 1006) relays data between the wireless device (10; 900; 1006) and a node (100; 1004) of the wireless communication network.

20. The method according to any of the preceding claims, wherein selection of the further wireless device (10; 900; 1006) as a relay node, for relaying data between the wireless device (10; 900; 1006) and a node (100; 1004) of the wireless communication network, depends on the obtained information.

21. A method of controlling wireless communication in a wireless communication network, the method comprising: a wireless device (10; 900; 1006) obtaining information whether the wireless device (10; 900; 1006) operates in a relaxed measurement mode of a cellular interface (920) of the wireless device (10; 900; 1006), and based on the obtained information, the wireless device (10; 900; 1006) controlling sidelink communication of the wireless device (10; 900; 1006) and a further wireless device (10; 900; 1006).

22. The method according to claim 21, comprising: the wireless device (10; 900; 1006) sending, via a sidelink communication interface of the wireless device, an indication (602) whether the wireless device (10; 900; 1006) operates in the relaxed measurement mode of the cellular interface (920).

23. The method according to claim 21 or 22, wherein carrier aggregation on a sidelink interface (910) to the further wireless device (10; 900; 1006) is controlled based on the obtained information.

24. The method according to claim 23, wherein enablement of carrier aggregation on the sidelink interface (910) depends on the obtained information.

25. The method according to claim 23 or 24, wherein disablement of carrier aggregation on the sidelink interface (910) depends on the obtained information.

26. The method according to any of claims 23 to 25, wherein selection between carrier aggregation modes on the sidelink interface (910) depends on the obtained information.

27. The method according to claim 26, wherein the carrier aggregation modes comprise one or more of: intra-band carrier aggregation, inter-band carrier aggregation, intra-band contiguous carrier aggregation, and intra-band non-contiguous carrier aggregation.

28. The method according to any of claims 23 to 27, wherein a number of carriers for carrier aggregation on the sidelink interface (910) depends on the obtained information.

29. The method according to any of claims 23 to 28, wherein selection of carriers for carrier aggregation on the sidelink interface (910) depends on the obtained information.

30. The method according to any of claims 23 to 29, wherein the carrier aggregation on the sidelink interface is at least in part configured based on signaling from a node (100; 1004) of the wireless communication network.

31. The method according to any of claims 23 to 30, wherein the carrier aggregation on the sidelink interface (910) is at least in part configured based on signaling from the further wireless device (10; 900; 1006).

32. The method according to any of claims 21 to 31 , wherein transmission of reference signals on a sidelink interface (910) to the further wireless device (10; 900; 1006) is controlled based on the obtained information.

33. The method according to claim 32, wherein a transmission periodicity of the reference signals on the sidelink interface (910) depends on the obtained information.

34. The method according to claim 32 or 33, wherein the transmission of reference signals on the sidelink interface (910) is at least in part configured based on signaling from a node (100; 1004) of the wireless communication network.

35. The method according to any of claims 32 to 34, wherein the transmission of reference signals on the sidelink interface (910) is at least in part configured based on signaling from the further wireless device (10; 900; 1006).

36. The method according to any of claims 21 to 35, wherein a discontinuous reception, DRX, configuration of a sidelink interface (910) to the further wireless device (10; 900; 1006) is controlled based on the obtained information.

37. The method according to claim 35, wherein the DRX configuration of the sidelink interface (910) is at least in part configured based on signaling from a node (100; 1004) of the wireless communication network.

38. The method according to claim 36 or 37, wherein the DRX configuration of the sidelink interface is at least in part configured based on signaling from the further wireless device.

39. The method according to any of claims 21 to 38, comprising: based on the sidelink communication with the further wireless device (10; 900; 1006), the wireless device (10; 900; 1006) relaying data between the further wireless device (10; 900; 1006) and a node (100; 1004) of the wireless communication network.

40. The method according to any of claims 21 to 39, comprising: based on one or more criteria, the wireless device (10; 900; 1006) determining whether the wireless device (10; 900; 1006) operates in the relaxed measurement mode of the cellular interface (920).

41. The method according to claim 40, wherein the one or more criteria comprise at least one criterion configured by a node (100; 1004) of the wireless communication network.

42. The method according to claim 40 or 41 , wherein the one or more criteria comprise at least one criterion based on detecting activity of the wireless device (10; 900; 1006) on the cellular interface (920).

43. The method according to claim 42, wherein the activity of the wireless device (10; 900; 1006) on the cellular interface (920) is detected based on Radio Resource Configuration, RRC, state of the cellular interface (920).

44. The method according to claim 42 or 43, wherein the activity of the wireless device (10; 900; 1006) on the cellular interface (920) is detected based on DRX configuration of the cellular interface (920).

45. A wireless device (10; 900; 1006) for operation in a wireless communication network, the wireless device (10; 900; 1006) being configured to: obtain information whether a further wireless device (10; 900; 1006) operates in a relaxed measurement mode of a cellular interface (920) of the further wireless device (10; 900; 1006), and based on the indication, control sidelink communication of the wireless device (10; 900; 1006) and the further wireless device (10; 900; 1006).

46. The wireless device (10; 900; 1006) according to claim 45, wherein the wireless device (10; 900; 1006) is configured to perform a method according to any one of claims 2 to 20.

47. The wireless device (10; 900; 1006) according to claim 45 or 46, comprising: at least one processor (950), and a memory (960) containing program code executable by the at least one processor (950), whereby execution of the program code by the at least one processor (950) causes the wireless device (10; 900; 1006) to perform a method according to any one of claims 1 to 20.

48. A wireless device (10; 900; 1006) for operation in a wireless communication network, the wireless device (10; 900; 1006) being configured to: obtain information whether the wireless device (10; 900; 1006) operates in a relaxed measurement mode of a cellular interface (920) of the wireless device (10; 900; 1006), and based on the indication, control sidelink communication of the wireless device (10; 900; 1006) and a further wireless device (10; 900; 1006).

49. The wireless device (10; 900; 1006) according to claim 48, wherein the wireless device (10; 900; 1006) is configured to perform a method according to any one of claims 22 to 44.

50. The wireless device (10; 900; 1006) according to claim 48 or 49, comprising: at least one processor (950), and a memory (960) containing program code executable by the at least one processor (950), whereby execution of the program code by the at least one processor (950) causes the wireless device (10; 900; 1006) to perform a method according to any one of claims 21 to 44.

51. A computer program or computer program product comprising program code to be executed by at least one processor (950) of a wireless device (10; 900; 1006) operating in a wireless communication network, whereby execution of the program code causes the wireless device (10; 900; 1006) to perform a method according to any one of claims 1 to 44.