WO2024154712A1

WO2024154712A1 - Method, user equipment and access network node

Info

Publication number: WO2024154712A1
Application number: PCT/JP2024/000887
Authority: WO
Inventors: Caroline Quanyi Liang; Xuelong Wang; Robert Arnott
Original assignee: Nec Corporation
Priority date: 2023-01-20
Filing date: 2024-01-16
Publication date: 2024-07-25
Also published as: GB202300921D0; GB2626373A

Abstract

A communication system including user equipment (UE) and an access network node are disclosed. The UE receives information for configuring measurements to be performed by the UE and information for configuring measurement reporting that defines criteria for triggering of measurement reporting events. The UE performs the configured measurements and when the event triggering criteria are met transmits, to the access network node, a measurement report for facilitating an L1/L2 triggered mobility decision at the access network node. The measurement report may be transmitted using a layer 1 or a layer 2 control signalling structure.

Description

METHOD, USER EQUIPMENT AND ACCESS NETWORK NODE

　　The present disclosure relates to a communication system.

　　The disclosure has particular but not exclusive relevance to wireless communication systems and devices thereof operating according to the 3rd Generation Partnership Project (3GPP) standards or equivalents or derivatives thereof (including LTE-Advanced, Next Generation or 5G networks, future generations, and beyond). The disclosure has particular, although not necessarily exclusive relevance to, inter-cell mobility triggered by L1/L2 signalling.

　　Under the 3GPP standards, a radio access network (RAN) node (or simply 'access node' or 'base station') is the communication entity via which communication devices (user equipment or 'UE') within a communication cell, operated by the RAN node, connect to a core network, and communicate to other communication devices or remote servers. Different generations of 3GPP technology use different terms to refer to such nodes (e.g., NodeB, or evolved NodeB (eNodeB / eNB) in LTE, or gNB in 5G). For simplicity, the present application will use the term RAN node or base station to refer to any such access network nodes.

　　In the current 5G architecture, for example, the RAN node structure may be split into two parts known as the Central Unit (CU) and the Distributed Unit (DU), connected by an F1 interface. This enables the use of a 'split' architecture, whereby the, typically 'higher', CU layers (for example, but not necessarily or exclusively), PDCP) and the, typically 'lower', DU layers (for example, but not necessarily or exclusively, RLC/MAC/PHY) to be implemented separately. Thus, for example, the higher layer CU functionality for a number of RAN nodes may be implemented centrally (for example, by a single processing unit, or in a cloud-based or virtualised system), whilst retaining the lower layer DU functionality locally, in each of the RAN nodes.

　　For simplicity, the present application will use the term mobile device, user device, or UE to refer to any communication device that is able to connect to the core network via one or more base stations. Although the present application may refer to mobile devices in the description, it will be appreciated that the technology described can be implemented on any communication devices (mobile and/or generally stationary) that can connect to a communications network for sending/receiving data, regardless of whether such communication devices are controlled by human input or software instructions stored in memory.

　　Historically, mobility between different cells in cellular communications has been based on communication at higher layers, such as layer 3 (e.g., the L3 or radio resource control (RRC) layer) signalling. More recently, with a view to providing enhanced mobility, consideration has given to developing and providing support for layer 1 (e.g., the L1 or physical (PHY) layer) and/or layer 2 (e.g., the L2 or media access control (MAC) layer) centric mobility (also referred to as L1/L2 centric mobility) rather than at higher layers (e.g., the RRC layer). Such L1/L2 centric mobility (also referred to as L1/L2 triggered mobility or 'LTM') has prospects for improving mobility for devices operating both below 7 GHz and in mmWave bands, for example by supporting lower handover latency and improved robustness.

　　There is, therefore, a need for the development of communication devices (such as base stations and/or UEs) that support efficient/flexible mechanisms for supporting LTM.

　　The disclosure aims to provide one or more apparatus and/or one or more associated methods that overcomes or at least partially ameliorates the above issues.

　　In one aspect there is provided a method performed by a user equipment (UE) the method comprising: receiving, from an access network node, first information for configuring at least one measurement to be performed by the UE, the first information including second information for configuring measurement reporting, the second information defining at least one parameter for at least one criterion for triggering of at least one measurement reporting event; performing the at least one measurement based on the first information; and in a case where the at least one criterion for triggering of at least one measurement reporting event has been met: transmitting, to the access network node, at least one measurement report for facilitating a mobility decision at the access network node, the at least one measurement report including at least one measurement result for the at least one measurement; wherein the at least one measurement report is transmitted using a layer 1 or layer 2 control signalling structure.

　　The first information may indicate a configuration of at least one resource in which at least one signal for measurement will be transmitted, the at least one signal for measurement including at least one of: at least one periodic signal; at least one semi-persistent signal; and/or at least one aperiodic signal. In a case where the first information indicates a configuration of at least one resource in which at least one periodic signal will be transmitted, event triggered transmission of the at least one measurement report based on measurement of the at least one periodic signal may be subject to dynamic activation or triggering by the base station. In a case where the first information indicates a configuration of at least one resource in which at least one periodic signal will be transmitted, event triggered transmission of the at least one measurement report based on measurement of the at least one periodic signal may not be subject to dynamic activation or triggering by the base station. In a case where the first information indicates a configuration of at least one resource in which at least one semi-persistent signal will be transmitted, event triggered transmission of the at least one measurement report based on measurement of the at least one semi-persistent signal may be subject to dynamic activation or triggering by the base station. In a case where the first information indicates a configuration of at least one resource in which at least one semi-persistent signal will be transmitted, event triggered transmission of the at least one measurement report based on measurement of the at least one semi-persistent signal may not be supported. In a case where the first information indicates a configuration of at least one resource in which at least one aperiodic signal will be transmitted, event triggered transmission of the at least one measurement report based on measurement of the at least one aperiodic signal may be subject to dynamic activation or triggering by the base station. In a case where the first information indicates a configuration of at least one resource in which at least one aperiodic signal will be transmitted, event triggered transmission of the at least one measurement report based on measurement of the at least one aperiodic signal may not be supported.

　　In the case where the at least one criterion for triggering of at least one measurement reporting event has been met, the method may comprise transmitting, to the access network node, an indication that resources are required for an uplink transmission, and receiving an allocation of resources of an uplink channel. The at least one measurement report may be transmitted using those resources. The indication may comprise a scheduling request. The indication may comprise a dedicated indication for indicating that a measurement report is available. The indication may comprise a fixed size indication, and the at least one measurement report may be transmitted using a fixed size control signal. The indication may be a single bit indication. The indication may indicate an amount of resources required for transmission of, or a size of, a control signal carrying an available measurement report. The indication may be a multi-bit indication. The indication may be transmitted using dedicated resources of a physical uplink control channel allocated by the access network node. The dedicated resources of the physical uplink control channel allocated by the access network node may be allocated as resources, of a scheduling request type, that are dedicated to transmission of the indication. The dedicated resources of the physical uplink control channel allocated by the access network node may be allocated as resources of a specific type that may be specifically dedicated to transmission of an indication for indicating that a measurement report is available. The indication may be transmitted using resources of a physical uplink control channel allocated by the access network node for transmission of a scheduling request.

　　The at least one measurement report may be transmitted using a control signalling structure in the form of a media access control (MAC) control element (CE) carrying the at least one measurement report. The at least one measurement report may be transmitted, in a physical uplink control channel, or a physical uplink shared channel, using a control signalling structure in the form of uplink control information (UCI). The at least one measurement report may include the at least one measurement result in association with at least one of: a physical cell identifier; and/or an identifier of at least one signal to which the result relates. The at least one measurement report may include the at least one measurement result in association with at least one of: an indication whether the at least one measurement result is subject to cell level filtering or beam level filtering; a measurement quantity for the at least one measurement result; a number of reported beams in the case that beam level filtering has been applied; an identifier of at least one serving cell and/or candidate cell for which the at least one measurement result applies; and/or an identifier of at least one resource set configured for measurement reporting to which the at least one measurement result relates. The at least one measurement result may be included in the measurement report subject to the at least one measurement result being no less than a specified threshold. The at least one measurement result may include a plurality of measurement results. A first measurement result of the plurality of measurement results may be represented in the at least one measurement report by an indication of an absolute value corresponding to the first measurement result, and at least one other measurement result of the plurality of measurement results may be represented in the at least one measurement report by an indication of a differential value, relative to the absolute value, corresponding to the at least one other measurement result.

　　The at least one parameter defined by the second information may comprise a threshold for triggering at least one measurement reporting event based on a comparison of at least one measurement result for a cell with the threshold. The at least one parameter defined by the second information may comprise an offset for triggering at least one measurement reporting event based on a comparison, with the offset, of a difference between at least one measurement result for a first cell and at least one measurement result for a second cell.

　　The at least one criterion for triggering the at least one measurement reporting event may be a criterion that is met without reference to a hysteresis parameter.

　　The second information may include third information for configuring a filtering or averaging type. The filtering or averaging type may be configured by the third information to be one of: no filtering or averaging; time domain filtering or averaging; cell level filtering or averaging; or both time domain and cell level filtering or averaging. In a case where the filtering or averaging type is configured to include filtering or averaging of a time domain averaging or filtering type, the second information may define an averaging window size.

　　The second information may include information for configuring the measurement reporting type to be both an event triggered type, and one of a periodic, a semi-persistent, or an aperiodic type. The at least one measurement report may include at least one measurement result of an event triggered type and at least one measurement result of the periodic, semi-persistent, or aperiodic type configured by the information for configuring the measurement reporting type. In a case where the information for configuring the measurement reporting type configures the measurement reporting to be both an event triggered type and one of a periodic or semi-persistent type, when the at least one criterion for triggering of at least one measurement reporting event has been met, transmission of the at least one measurement report may start in accordance with the configured periodic or semi-persistent type of measurement reporting. In a case where the information for configuring the measurement reporting type configures the measurement reporting to be both an event triggered type and one of a periodic or semi-persistent type, transmission of the at least one measurement report in accordance with the configured periodic or semi-persistent type of measurement reporting may occur only when the at least one criterion for triggering of at least one measurement reporting event has been met. The transmission of the at least one measurement report in accordance with the configured periodic or semi-persistent type of measurement reporting may occur in accordance with a periodicity configured by the second information subject to the at least one criterion for triggering of at least one measurement reporting event has been met In a case where the information for configuring the measurement reporting type configures the measurement reporting to be both an event triggered type and one of a periodic or semi-persistent type, the second information may define at least one threshold for starting and/or stopping measurement reporting of the configured periodic or semi-persistent type, and transmission of the at least one measurement report in accordance with the configured periodic or semi-persistent type of measurement may be started or stopped based on the at least one threshold for starting and/or stopping measurement reporting. The at least one threshold for starting and/or stopping measurement reporting may comprise at least one threshold for a layer 3 measurement. The at least one threshold for starting and/or stopping measurement reporting may comprise at least one threshold for a layer 1 measurement.

　　The at least one measurement may include measurements performed in respect of a plurality of beams and the method may further comprise selecting beams for which measurement results should be included in the measurement report, up to a maximum number of beams, using a selection procedure. The selection procedure may include ranking the beams based on at least one respective measurement result for each beam and respectively selecting, based on the ranking, at least one beam for each of a plurality of carrier frequencies and/or a plurality of cells until the maximum number of beams has been reached. Each of the plurality of carrier frequencies and/or the plurality of cells may have an associated priority, and the order in which the selecting of the at least one beam for each of the plurality of carrier frequencies and/or the plurality of cells occurs may be based on the associated priority for each of the plurality of carrier frequencies and/or the plurality of cells. The selecting of the at least one beam for each of the plurality of carrier frequencies and/or the plurality of cells may be subject to a maximum number of beams, and/or a maximum number of cells, per carrier. The selecting of the at least one beam for each of the plurality of carrier frequencies and/or the plurality of cells may be subject to a maximum number of beams per cell.

　　The method may further comprise receiving, from the access network node, a cell switch command for the mobility procedure, the cell switch command including a transmission configuration indication (TCI) that is common to a plurality of channels and/or signals, and receiving a respective channel specific or signal specific TCI for each of a plurality of channels and/or signals. The respective channel specific or signal specific TCI for each of a plurality of channels and/or signals may be received separately following the cell switch command. The respective channel specific or signal specific TCI for each of a plurality of channels and/or signals may be included in the cell switch command.

　　The mobility procedure may be a mobility procedure that is triggered at a layer below layer 3.

　　In one aspect there is provided a user equipment (UE) comprising: means for receiving, from an access network node, first information for configuring at least one measurement to be performed by the UE, the first information including second information for configuring measurement reporting, the second information defining at least one parameter for at least one criterion for triggering of at least one measurement reporting event; means for performing the at least one measurement based on the first information; and means for, in a case where the at least one criterion for triggering of at least one measurement reporting event has been met, transmitting, to the access network node, at least one measurement report for facilitating a mobility decision at the access network node, the at least one measurement report including at least one measurement result for the at least one measurement; wherein the at least one measurement report is transmitted using a layer 1 or layer 2 control signalling structure.

　　In one aspect there is provided a method performed by an access network node the method comprising: transmitting, to a user equipment (UE), first information for configuring at least one measurement to be performed by the UE, the first information including second information for configuring measurement reporting, the second information defining at least one parameter for at least one criterion for triggering of at least one measurement reporting event; receiving, in a case where the at least one criterion for triggering of at least one measurement reporting event has been met, from the UE, at least one measurement report for facilitating a mobility decision at the access network node, the at least one measurement report including at least one measurement result for at least one measurement performed by the UE; and making a mobility decision based on the at least one measurement report; wherein the at least one measurement report is transmitted using a layer 1 or layer 2 control signalling structure.

　　In one aspect there is provided an access network node comprising: means for transmitting, to a user equipment (UE), first information for configuring at least one measurement to be performed by the UE, the first information including second information for configuring measurement reporting, the second information defining at least one parameter for at least one criterion for triggering of at least one measurement reporting event; means for receiving, in a case where the at least one criterion for triggering of at least one measurement reporting event has been met, from the UE, at least one measurement report for facilitating a mobility decision at the access network node, the at least one measurement report including at least one measurement result for at least one measurement performed by the UE; and means for making a mobility decision based on the at least one measurement report; wherein the at least one measurement report is transmitted using a layer 1 or layer 2 control signalling structure.

　　Aspects of the disclosure extend to corresponding systems, apparatus, and computer program products such as computer readable storage media having instructions stored thereon which are operable to program a programmable processor to carry out a method as described in the aspects and possibilities set out above or recited in the claims and/or to program a suitably adapted computer to provide the apparatus recited in any of the claims.

　　Each feature disclosed in this specification (which term includes the claims) and/or shown in the drawings may be incorporated in the disclosure independently of (or in combination with) any other disclosed and/or illustrated features where it is technically feasible to do so. In particular but without limitation the features of any of the claims dependent from a particular independent claim may be introduced into that independent claim in any combination or individually wherever doing so does not cause a technical incompatibility or result in something that does not make technical sense.

　　Embodiments of the disclosure will now be described, by way of example, with reference to the accompanying drawings in which:
Fig. 1 schematically illustrates a mobile ('cellular' or 'wireless') telecommunication system; Fig. 2 illustrates a typical frame structure that may be used in the telecommunication system of Fig. 1; Fig.3 illustrates a number of information elements that may be used for CSI-RS measurement configuration signalling in the telecommunication system of Fig. 1; Fig. 4 is a simplified trigger quantity vs. time graph illustrating triggering of a measurement reporting event; Fig. 5A illustrates parts of information structures for reporting and event configurations that may be used in the telecommunication system of Fig. 1; Fig. 5B illustrates parts of information structures for reporting and event configurations that may be used in the telecommunication system of Fig. 1; Fig. 6 is a schematic block diagram illustrating the main components of a UE for the telecommunication system of Fig. 1; Fig. 7 is a schematic block diagram illustrating the main components of a base station for the telecommunication system of Fig. 1; Fig. 8 is a simplified sequence diagram illustrating a possible two stage mechanism for L1 event based measurement reporting for the telecommunication system of Fig. 1; Fig. 9 is a simplified sequence diagram illustrating another possible two stage mechanism for L1 event based measurement reporting for the telecommunication system of Fig. 1; Fig. 10 is a simplified sequence diagram illustrating another possible two stage mechanism for L1 event based measurement reporting for the telecommunication system of Fig. 1; Fig. 11 is a simplified sequence diagram illustrating another possible two stage mechanism for L1 event based measurement reporting for the telecommunication system of Fig. 1; Fig. 12A illustrates parts of information structures for L1 reporting and L1 event configurations that may be used in the telecommunication system of Fig. 1; Fig. 12B illustrates parts of information structures for L1 reporting and L1 event configurations that may be used in the telecommunication system of Fig. 1; Fig. 13 illustrates a method that may be performed by a UE 3 for selecting a subset of measurement results to report in the telecommunication system of Fig. 1; and Fig. 14 is a simplified sequence diagram illustrating of part of a procedure for LTM for the telecommunication system of Fig. 1.

Overview
　　An exemplary telecommunication system will now be described in general terms, by way of example only, with reference to Figs. 1 to 5.

　　Fig. 1 schematically illustrates a mobile ('cellular' or 'wireless') communication system 1 to which embodiments of the present disclosure are applicable.

　　In the communication system 1 user equipment (UEs) 3 (3-1, 3-2, 3-3) (e.g. mobile telephones and/or other mobile devices) can communicate with each other via a corresponding radio access network (RAN) node 5-1, 5-2 that operates according to one or more compatible radio access technologies (RATs). In the illustrated example, each RAN node 5 (5-1, 5-2) comprises a NR/5G base station or 'gNB' that respectively operates one or more associated cells 9 (9-1, 9-2). In Fig. 1, one of the RAN nodes 5-1 is shown as providing cellular coverage via a plurality of transmission / reception points (TRPs) 5-1a to 5-1d, each of which, in this example, has a respective different physical layer cell identity (PCI). It will, nevertheless, be appreciated, that the different TRPs 5-1a to 5-1d could share a common PCI. The other RAN node 5-2 is shown as providing coverage via a single TRP although it will be appreciated that coverage may be provided via plural TRPs. Each TRP may comprise a respective antenna panel at the same location or a separate remotely located radio head or the like. In the illustrated communication system 1, the coverage provided by each base station 5 (or associated TRP 5-1a to 5-1d of the base station 5) may be by means of a plurality of beams B (B1, B2 … Br, Br+1 … BN). It will be appreciated that while, for clarity of illustration, only a selection of possible beams B are shown for TRP 5-1a, the set of beams may include any suitable number of beams and each TRP / base station 5 may operate a respective set of beams or may provide coverage in a non-beamformed manner.

　　Communication via each base station 5 is typically routed through a core network 7 (e.g. a 5G core network or evolved packet core network (EPC)).

　　As those skilled in the art will appreciate, whilst three UEs 3 and two base stations 5 are shown in Fig. 1 for illustration purposes, the system, when implemented, will typically include other base stations and UEs.

　　Each base station 5 controls one or more associated cells 9 either directly, or indirectly via one or more other nodes (such as home base stations, relays, remote radio heads, distributed units, and/or the like). It will be appreciated that the base stations 5 may be configured to support 4G, 5G, 6G, and/or any other 3GPP or non-3GPP communication protocols.

　　The UEs 3 and their serving base station 5 are connected via an appropriate air interface (for example the so-called 'Uu' interface and/or the like). Neighbouring base stations 5 may be connected to each other via an appropriate base station to base station interface (such as the so-called 'X2' interface, 'Xn' interface and/or the like).

　　The core network 7 includes a number of logical nodes (or 'functions') for supporting communication in the telecommunication system 1. In this example, the core network 7 comprises control plane functions (CPFs) 10 and one or more user plane functions (UPFs) 11. The CPFs 10 include one or more Access and Mobility Management Functions (AMFs) 10-1, one or more Session Management Functions (SMFs) and a number of other functions 10-n.

　　The base station 5 is connected to the core network nodes via appropriate interfaces (or 'reference points') such as an N2 reference point between the base station 5 and the AMF 10-1 for the communication of control signalling, and an N3 reference point between the base station 5 and each UPF 11 for the communication of user data. The UEs 3 are each connected to the AMF 10-1 via a logical non-access stratum (NAS) connection over an N1 reference point (analogous to the S1 reference point in LTE). It will be appreciated, that N1 communications are routed transparently via the base station 5.

　　One or more UPFs 11 are connected to an external data network (e.g. an IP network such as the internet) via reference point N6 for communication of the user data.

　　The AMF 10-1 performs mobility management related functions, maintains the non-NAS signalling connection with each UE 3 and manages UE registration. The AMF 10-1 is also responsible for managing paging. The SMF 10-2 provides session management functionality (that formed part of MME functionality in LTE) and additionally combines some control plane functions (provided by the serving gateway and packet data network gateway in LTE). The SMF 10-2 also allocates IP addresses to each UE 3.

　　The base station 5 is also configured for transmission of, and the UEs 3 are configured for the reception of, control information and user data via a number of downlink (DL) physical channels and for transmission of a number of physical signals. The DL physical channels correspond to resource elements (REs) carrying information originated from a higher layer, and the DL physical signals are used in the physical layer and correspond to REs which do not carry information originated from a higher layer.

　　The physical channels may include, for example, a physical downlink shared channel (PDSCH), a physical broadcast channel (PBCH), and a physical downlink control channel (PDCCH). The PDSCH carries data sharing the PDSCH's capacity on a time and frequency basis. The PDSCH can carry a variety of items of data including, for example, user data, UE-specific higher layer control messages mapped down from higher channels, system information blocks (SIBs), and paging. The PDCCH carries downlink control information (DCI) for supporting a number of functions including, for example, scheduling the downlink transmissions on the PDSCH and also the uplink (UL) data transmissions on the physical uplink shared channel PUSCH. The PBCH provides UEs 3 with the Master Information Block, MIB. It also, in conjunction with the PDCCH, supports the synchronisation of time and frequency, which aids cell acquisition, selection and re-selection.

　　The DL physical signals may include, for example, reference signals (RSs) and synchronization signals (SSs). A reference signal (sometimes known as a pilot signal) is a signal with a predefined special waveform known to both the UE 3 and the base station 5. The reference signals may include, for example, cell specific reference signals, UE-specific reference signal (UE-RS), downlink demodulation signals (DMRS), and channel state information reference signal (CSI-RS).

　　Similarly, the UEs 3 are configured for transmission of, and the base station 5 is configured for the reception of, control information and user data via a number of uplink (UL) physical channels corresponding to REs carrying information originated from a higher layer, and UL physical signals which are used in the physical layer and correspond to REs which do not carry information originated from a higher layer. The physical channels may include, for example, a physical uplink shared channel (PUSCH), a physical uplink control channel (PUCCH), and/or a physical random-access channel (PRACH). The UL physical signals may include, for example, demodulation reference signals (DMRS) for a UL control/data signal, and/or sounding reference signals (SRS) used for UL channel measurement.

　　Referring to Fig. 2, which illustrates the typical frame structure that may be used in the telecommunication system 1, the base station 5 and UEs 3 of the communication system 1 communicate with one another using resources that are organised, in the time domain, into frames of length 10ms. Each frame comprises ten equally sized subframes of 1ms length. Each subframe is divided into one or more slots comprising 14 Orthogonal frequency-division multiplexing (OFDM) symbols of equal length.

　　As seen in Fig. 2, the communication system 1 supports multiple different numerologies (subcarrier spacing (SCS), slot lengths and hence OFDM symbol lengths). Specifically, each numerology is identified by a parameter, μ, where μ=0 represents 15 kHz (corresponding to the LTE SCS). Currently, the SCS for other values of μ can, in effect, be derived from μ=0 by scaling up in powers of 2 (i.e. SCS = 15 x 2μ kHz). The relationship between the parameter, μ, and SCS (Δf) is as shown in Table 1:

Antenna Ports and Quasi Co-Location (QCL)
　　The base station 5 of the communication system 1 includes an antenna that may have one or more antenna panels, each of which typically comprises a plurality of physical antenna elements. Similarly, each UE 3 may also have an antenna having multiple antenna elements.
The use of antennas with multiple physical antenna elements allows the base station 5 and UE 3 to perform transmissions (and receptions) using logical antenna ports that are mapped to a subset of one or more of the physical antenna elements. Transmissions sharing the same antenna port will therefore experience the same propagation channel, whereas transmissions using different antenna ports will experience different propagation channels. Nevertheless, there are scenarios where even transmissions using different antenna ports will experience radio channels having some common propagation characteristics. In this case the antenna ports (and the associated transmissions) may be said to be quasi co-located (QCL).

　　The radio channel characteristics which may be common for different QCL antenna ports include, for example: Doppler shift; Doppler spread; average delay; delay spread; and/or spatial receiver parameters. Treating antenna ports, and associated transmissions (e.g., of reference / synchronisation signals), as QCL can help with channel estimation, synchronisation, frequency offset estimation, or the like, at the UE 3. For example, if two antenna ports are considered to be QCL in respect of particular parameters (say doppler shift and average delay) then a UE 3 can determine those parameters for one antenna port and apply them in respect of both antenna ports.

　　QCL antenna ports need not be geographically co-located (although they may be). For example, the physical antennas / antenna elements may belong to different TRPS 5-1a to 5-1d (e.g., when co-ordinated multipoint (CoMP) transmission / multi-TRP transmission is being employed).

　　The communication system 1 supports the following four types of QCL:
-　　Type A (with common characteristics: Doppler shift; Doppler spread; average delay; and delay spread);
-　　Type B (with common characteristics: Doppler shift; and Doppler spread);
-　　Type C (with common characteristics: Doppler shift; and average delay); and
-　　Type D (with common spatial receiver parameters).

　　QCL can be used for assisting reception of both the downlink shared and control physical channels (PDSCH and PDCCH). For example, the serving base station 5 can indicate (e.g., via a combination of RRC and/or MAC signalling) that a specific synchronisation signal block (SSB) uses an antenna port that is QCL with an antenna port used for the PDSCH and/or PDCCH. Similarly, the antenna port used by a particular CSI-RS may be indicated (e.g., via a combination of RRC and/or MAC signalling) to be QCL with an antenna port used for the PDSCH and/or PDCCH.

Bandwidth Parts (BWPs)
　　In the communication system 1 the cell bandwidth can be divided into multiple bandwidth parts (BWPs) that each start at a respective common resource block (RB) and respectively comprises of a set of contiguous RBs with a given numerology (sub-carrier spacing, 'SCS', and cyclic prefix, 'CP') on a given carrier. It will be appreciated that conventionally the number of downlink symbols, uplink symbols, and flexible symbols in each slot of the slot configuration (e.g., common or dedicated) would be common to each configured BWP.

　　The UEs 3 and base station 5 of the communication system 1 are thus configured for operation using BWPs. For each serving cell of a UE 3, the base station 5 can configure at least one downlink (DL) BWP (e.g. an initial DL BWP). The base station 5 may configure the UE 3 with up to a maximum (typically four) DL BWPs with only a single DL BWP being active at a given time. The UE 3 is not expected to receive PDSCH, PDCCH, or CSI-RS (except for radio resource management (RRM)) outside an active bandwidth part. Where the serving cell is configured with an uplink (UL), the base station 5 can configure at least one UL BWP (e.g. an initial UL BWP). The base station 5 may configure the UE 3 with up to a maximum (typically four) UL BWPs with only one UL BWP being active at a given time. The UE 3 does not transmit PUSCH or PUCCH outside an active bandwidth part. For an active cell, the UE 3 does not transmit SRS outside an active bandwidth part. It will be appreciated that the slot format indicator (e.g., an SFI-index field value) in the dynamic slot configuration DCI format may indicate to a UE 3 a slot format for each slot in a number of slots for each DL BWP or each UL BWP.

　　A BWP identifier or index (BWP-ID) is used to refer to BWPs (in UL and DL independently). Various radio resource control (RRC) configuration procedures can thus use the BWP-ID to associate themselves with a particular BWP.

　　While for paired spectrum (FDD), DL BWPs and UL BWPs are configured separately, for unpaired spectrum (TDD), a DL BWP is effectively linked to (paired with) a UL BWP, with the paired DL BWP and UL BWP sharing the same BWP-ID and centre frequency (but possibly different bandwidths).

　　Specifically, the base station 5 is able to configure an initial DL BWP (e.g. by means of an initialDownlinkBWP IE) via system information (e.g. system information block 1, 'SIB1') and/or via dedicated (e.g. RRC) signalling (e.g. an RRC reconfiguration, RRC resume, or RRC setup message). For example, the common parameters for the initial DL BWP may be provided via system information whereas UE specific parameters may be provided via dedicated signalling (e.g. in a ServingCellConfig IE within an RRC message that contains a dedicated, UE-specific, BWP configuration). The dedicated signalling may also contain some cell-specific information which may be useful for specific scenarios (e.g. handover).

　　The base station 5 is able to configure an initial UL BWP (e.g. by means of an initialUplinkBWP IE) via system information (e.g. system information block 1, 'SIB1') and/or via dedicated (e.g. RRC) signalling (e.g. an RRC reconfiguration, RRC resume, or RRC setup message). For example, the common parameters for one or more initial UL BWPs may be provided via system information whereas UE specific parameters may be provided via dedicated signalling (e.g. in a ServingCellConfig IE within an RRC message that contains a dedicated, UE-specific, BWP configuration). This provides configuration information either for a so-called special cell (SpCell) - which is a PCell of a master cell group (MCG) or secondary cell group (SCG) - or a secondary cell (SCell).

　　The initial DL and UL BWPs are used at least for initial access before an RRC connection is established. The initial BWP is known as BWP#0 as it has a BWP identifier (or 'index') of zero. Prior to receiving system information defining a UE's initial DL BWP, the DL BWP for each UE 3 has a frequency range and numerology corresponding to a control resource set (CORESET) - e.g. CORESET #0 - defined by a master information block (MIB) (or possibly dedicated RRC signalling). The CORESET is used to carry downlink control information (DCI) transmitted via a physical downlink control channel (PDCCH) for scheduling system information blocks.

　　After receiving the system information (e.g. SIB1) a UE 3 uses the BWP configuration defined by that system information to configure the initial DL BWP and initial UL BWP. The configured initial UL BWP is then used to initiate a random-access procedure for setting up an RRC connection. The base station 5 configures the frequency domain location and bandwidth of the initial DL BWP in the system information so that the initial DL BWP contains the entire CORESET #0 in the frequency domain.

　　For each DL BWP in a set of DL BWPs for a primary cell, a UE 3 can be configured with CORESETs for every type of common search space (CSS) set and for a UE-specific search space (USS) set. For each UL BWP in a set of UL BWPs of a primary cell, or of a PUCCH-secondary cell, the UE 3 is configured resource sets for PUCCH transmissions.

　　The UE 3 is configured for switching its active BWP between its configured BWPs when required. For example, switching at the UE 3 may be initiated by receipt of a scheduling DCI, by expiry of an inactivity timer (e.g., a BWPInactivityTimer), and/or by initiation of a random-access procedure.

Synchronisation Signal Blocks (SSBs)
　　The base station 5 is also configured to transmit synchronisation signal blocks (SSBs) periodically in one or more cells 9 that it operates. The SSB includes both synchronisation signals (e.g., a primary synchronisation signal (PSS) and a secondary synchronisation signal (SSS)) and a physical broadcast channel (PBCH) carrying a master information block (MIB) that provides at least part of the minimum system information for accessing the corresponding cell 9 (e.g., parameters required for acquiring system information block 1 (SIB1) which carries other minimum system information).

　　Each UE 3 is configured to search for SSBs when scanning for a cell to camp on and to decode the associated PBCH before proceeding to decode other system information transmitted on the PDSCH. Each UE 3 is also configured to perform measurements on specific resources configured for the SSBs, for example reference signal received power (RSRP), reference signal received quality (RSRQ), and /or signal to interference and noise ratio (SINR) measurements or the like.

Channel State Information Reference Signals (CSI-RS) and Demodulation Reference Signals (DMRS)
　　The base station 5 is also configured to transmit reference signals (RS) in one or more cells 9 that it operates. These reference signals include channel state information RS (CSI-RS) and demodulation RS (DMRS).

　　The CSI-RS may be used by the UE 3 for a number of different purposes including, for example, CSI reporting in which the UE 3 derives channel state information including one or more channel quality indicators (CQIs), rank indicators (RIs), and/or precoding matrix indicators (PMIs) from CSI-RS measurements and reports them to the base station 5 in a CSI report.

　　The CSI-RS may also be used by the UE 3 for beam management including the refinement of initial beam selection based on SSBs. For example, the base station 5 may use a set of relatively broad beams may be used for transmission of the SSBs and a set of narrower (more directional) beams for the CSI-RS. The UE 3 can be configured, by the base station 3, to measure each CSI-RS transmission to identify the best CSI-RS beam and to report this to the base station 5 (e.g., by means of a CSI report including a CSI-RS indicator (CRI) identifying the strongest CSI-RS and hence CSI-RS beam). The UE 3 may also be configured to report a layer 1 RSRP (L1-RSRP) and/or layer 1 signal to interference and noise ratio (L1-SINR) which has been measured for the strongest CSI-RS.

　　CSI-RS may either be either zero power (ZP-CSI-RS) or non-zero power (NZP-CSI-RS). NZP-CSI-RS are used for most of the procedures including channel measurement, beam management, beam measurement, connected mode mobility etc. ZP-CSI-RS are empty resource elements, used primarily for interference measurement.

　　There are also several other ways in which the CSI-RS may be used including, for example, for connected mode mobility, radio link failure detection, beam failure detection / recovery, and fine timing of time and/or frequency synchronisation.

　　The DMRS include DMRS for the PBCH, DMRS for the PDCCH and DMRS for the PDSCH. The DMRS for the PBCH are used by the UE 3 to estimate the propagation channel experienced by the PBCH for the purposes of demodulating the PBCH and subsequent decoding of system information (e.g., carried by the MIB). The DMRS for the PDCCH are used by the UE 3 to estimate the propagation channel experienced by the PDCCH for the purposes of demodulating the PDCCH and subsequent decoding of DCI.

　　A DMRS for the PDSCH is transmitted in combination with the associated PDSCH using the same precoding and logical antenna ports. Accordingly the DMRS and associated PDSCH both experience the same combined propagation channel. The DMRS is transmitted using a sequence that is known to the UE 3 and hence the UE 3 can determine the characteristics (propagation coefficients) of the propagation channel based on a comparison of the received DMRS with the original DMRS as transmitted by the base station 5. The UE 3 is then able to decode the associated PDSCH based on the derived propagation coefficients.

　　Data communicated on the PDSCH (and the associated DMRS) may be transmitted in parallel transmission layers and/or may be beamformed.

CSI Reporting
　　The base station 5 can configure how the UE 3 measures and reports CSI using appropriate measurement configuration signalling.
A CSI report may include a Channel Quality Indicator (CQI), a precoding matrix indicator (PMI), a CSI-RS resource indicator (CRI), SS/PBCH Block Resource indicator (SSBRI), a layer indicator (LI), a rank indicator (RI), a layer 1 reference signal received power (L1-RSRP), a layer 1 signal to interference and noise ratio (L1-SINR), and/or a Capability[Set]Index. A CSI report may be sent as uplink control information (UCI) in a PUCCH or a UCI part of a PUSCH.

　　The CQI is an index (typically 4 bits) value representing a signal to interference and noise ratio (SINR). The CQI value also corresponds to a modulation and coding scheme (MCS) to be used for each layer. The RI indicates a number of MIMO transmission layers requested by the UE 3 (albeit the base station 5 may not use the requested number of MIMO transmission layers). The PMI is used by the UE 3 to report parameters defining a preferred precoding matrix to be applied for downlink transmissions (albeit the base station 5 may not use the requested precoding). A layer indicator (LI) may also be included in the CSI report for identifying the strongest layer from the set of layers indicated by the RI.

　　The L1-RSRP and/or L1-SINR may be measured for SSB channel measurement resources or for CSI-RS channel measurement resources.

　　Fig. 3 illustrates a number of information elements that may be used for such measurement signalling in a 5G system according to the relevant 3GPP standards. It will be appreciated that these are shown for illustrative purposes and are purely exemplary, other information elements (IEs) may be present in addition, or as an alternative, to those shown.

　　The base station 5 can, for example, use the measurement configuration signalling (e.g., using a CSI-measconfig IE) to configure the UE 3 to measure and report specific resources used for CSI-RS (e.g., using the CSI-ReportConfig IE in Fig. 3). Multiple different reporting configurations can be configured and identified by an appropriate identifier (e.g., the CSI-ReportConfigID IE in Fig. 3).

　　The base station 5 can, for example, configure the UE 3 to provide different types of CSI reports (e.g., using the CSI-ReportConfig IE in Fig. 3) providing different information, depending on the requirements for the use case, by setting a reporting quantity parameter (e.g., the reportQuantity IE in Fig. 3) appropriately. For example, the reporting quantity may indicate the CSI-related, L1-RSRP-related, or L1-SINR-related quantities to report. The UE 3 may, for example, be configured: to report only RI, and CQI for one or more associated CRIs, by setting the reporting quantity parameter appropriately (e.g., to cri-RI-CQI); to report RI, PMI and CQI for one or more associated CRIs by setting the reporting quantity parameter appropriately (e.g., to cri-RI-PMI-CQI), or to report RI, LI, PMI and CQI for one or more associated CRIs by setting the reporting quantity parameter appropriately (e.g., to cri-RI-LI-PMI-CQI). Similarly, for beam management procedures, the UE 3 may be configured to report RSRP or SINR for one or more associated CRIs, by setting the reporting quantity parameter appropriately (e.g., to cri-RSRP or cri-SINR), to report RSRP or SINR for one or more associated SSBs, by setting the reporting quantity parameter appropriately (e.g., to ssb-Index-RSRP or ssb-Index- SINR).

　　The base station 5 can also configure the UE 3 to provide CSI reports based on different report timing configurations (e.g., using a reportConfigType IE in the CSI-ReportConfig IE as shown in Fig. 3). For example, the UE 3 may be configured for persistent reporting, semi-persistent reporting on the PUSCH, semi-persistent reporting on the PUCCH, or aperiodic reporting. The time domain behaviour of the CSI report configuration indicated by the higher layer report configuration type parameter has a configured periodicity and slot offset that applies in the numerology of the UL BWP in which the CSI report is configured for transmission on.

　　Aperiodic reporting and semi-persistent reporting on PUSCH may be triggered using a PUSCH DCI. For example, DCI (e.g., using DCI format 0_1 or DCI format 0_2). For example, CSI reporting may be triggered by the content of a CSI request, included in the DCI, that has a size (in number of bits) corresponding to a higher layer trigger size parameter (e.g., the reportTriggerSize parameter in the case of DCI format 0_1 or the reportTriggerSizeDCI-0-2 in the case of DCI format 0_2). The size of the CSI request field may, for example, be configured to be one of the set of possible numbers of bits: {0, 1, 2, 3, 4, 5, 6}. The CSI request typically has a value that points to a respective index of each of one or more corresponding aperiodic trigger states (e.g., configured in the CSI-AeriodicTriggerStateList IE shown in Fig. 3). Each of these trigger states is associated with one or more corresponding CSI report configurations (e.g., identified by one or more associated CSI-ReportConfig IEs in Fig. 3). The time and frequency resources that can be used by the UE to report CSI are controlled by the base station.

　　Semi-persistent reporting on PUSCH may be triggered in a similar way (e.g., by use of DCI identifying one or more CSI-ReportConfig IEs of one or more CSI-SemiPersistentOnPUSCH-TriggerStates listed in the CSI-SemiPersistentOnPUSCH-TriggerStateList shown in Fig. 3).

　　Semi-persistent reporting on PUCCH may be triggered using a MAC control element (MAC CE, e.g., as illustrated in Fig. 3).

　　Each CSI report configuration identifies at least one CSI resource configuration (e.g., using a CSI-ResourceConfigId IE as illustrated in Fig. 3) for measurement. The identified CSI resource configuration is defined by a corresponding IE (e.g., using the CSI-ResourceConfigId IE in Fig. 3) that includes a list of identifiers corresponding to one or more sets of CSI resources (e.g. a list of one or more NZP-CSI-RS-ResourceSetIDs for non-zero power CSI-RS as shown in Fig. 3) and associated configuration information. The associated configuration information may, for example, identify an associated bandwidth part (e.g., by means of the BWP ID in Fig. 3) and a resource type (e.g., by means of the resourceType IE in Fig. 3). The identified resource type may, for example, identify the CSI-RS resource to be a periodic, a semi-persistent, or an aperiodic type. Each resource set comprises one or more specific CSI resource configurations represented by associated identifiers (e.g. one or more NZP-CSI-RS-ResourceIDs for non-zero power CSI-RS as shown in Fig. 3) that each point to the specific configuration information (e.g. defined by an NZP-CSI-RS-Resource IE for non-zero power CSI-RS as shown in Fig. 3) for that CSI resource configuration).

　　For CQI, PMI, CRI, SSBRI, LI, RI, L1-RSRP, L1-SINR, Capability[Set]Index a UE is configured by higher layers with one or more CSI report configuration reporting settings (e.g., defined in the CSI-ReportConfig IE), one or more CSI resource configuration resource settings (e.g., defined in the CSI-ReportConfig IE), and one or two lists of trigger states (e.g., given by the higher layer parameter CSI-AperiodicTriggerStateList and/or the higher layer parameter CSI-SemiPersistentOnPUSCH-TriggerStateList). Each trigger state of a list of aperiodic CSI trigger states (e.g., defined by the CSI-AperiodicTriggerStateList IE) may define a list of associated CSI report configurations indicating the resource set IDs for channel measurement and possibly interference measurement. Each trigger state of a list of semi-persistent CSI trigger states (e.g., defined by the CSI-SemiPersistentOnPUSCH-TriggerStateList IE) may contain a single associated CSI report configuration.

　　Each reporting setting is associated with a single downlink BWP (e.g., indicated by the higher layer parameter BWP-Id given in an associated CSI-ResourceConfig IE for channel measurement) and contains one or more parameters for one CSI reporting band: measurement restriction configurations, and the CSI-related quantities to be reported by the UE such as the LI, L1-RSRP, L1-SINR, CRI, and SSBRI.

　　Accordingly, the base station can configure multiple CSI report configuration instances and CSI resource configuration instances. It will be appreciated that multiple resource sets can be configured per CSI resource config for the case of aperiodic CSI RS resources. The same number of CSI-RS ports are assumed for multiple CSI-RS resources within a given resource set.

　　In this way reporting of specific CSI resource sets for specific use cases may be configured. For example, a CSI-RS resource set may be configured that includes CSI-RS resources for different beams for beam management purposes. A CSI-RS resource set may be configured that includes a single CSI-RS resource for a number, N, of ports for channel estimation purposes.

　　Different resource sets may also be configured per resource configuration in for the case of multiple transmission reception points (TRPs). In this scenario, different resource sets can be part of same CSI resource configuration for aperiodic CSI reporting or can be part of different CSI resource configuration for periodic/semi-persistent CSI reporting. It will, nevertheless, be appreciated that in the case of the same number of ports for all TRPs it is possible to configure CSI-RS resources belonging to different TRPs within same resource set.

　　In another example, a CSI report for multiple secondary cells (SCells) can be triggered together by including CSI reporting configurations for different SCells within the information defining a single CSI aperiodic trigger state.

　　The base station 5 can also configure the UE 3 to provide either a wideband or a subband granularity of reporting (e.g., using a reportFreqConfiguration IE in a CSI-ReportConfig IE). For example CQI and/or partial PMI can be reported per subband setting a corresponding indicator (e.g., a cqi-FormatIndicator IE and/or a pmi-FormatIndicator IE respectively) appropriately (e.g., to widebandCQI or subbandCQI and/or to widebandPMI or subbandPMI respectively).

　　The base station 5 can also configure the UE 3 with a time restriction for channel measurements (and/or interference measurements). When the time restriction is configured, the UE 3 is configured to derive the measurements for computing CSI values based only on the last measured CSI-RS occasion associated with the CSI report.

　　It will be appreciated that the UE 3 may need to transmit quite a few CSI reports (based on the CSI configuration) but there may be limited space available in PUCCH or uplink control UCI part of the PUSCH. Moreover, the CSI report payload size can increase significantly in presence of subband based reporting. Hence, prioritization rules are defined for indicating which CSI report parameters should be transmitted with the highest priority.

　　For CSI reporting of RI, CQI and PMI, a CSI report for a single CSI resource may be divided into two parts: a first part containing RI, CRI, CQI for a first codeword; and a second part containing PMI and CQI for a second codeword. The first part can be transmitted in whole while it is possible to omit a portion of the second part (depending on allowed size of UCI). For UCI coding, the first part of each CSI report is encoded into the UCI, and the second part of the CSI report is encoded based on amount of space available.

L1-RSRP computation and reporting
　　For the purposes of L1-RSRP computation a UE 3 may be configured with CSI-RS resources, SSB resources or both CSI-RS and SSB resources (when resource-wise 'type C' and/or 'type D' quasi co-located where applicable).

　　A UE 3 may typically be configured with a CSI-RS resource setting of up to 16 CSI-RS resource sets typically having up to 64 resources within each set. The total number of different CSI-RS resources over all resource sets is generally no more than 128.

　　For the purposes of L1-RSRP reporting, a higher layer parameter may be provided in the CSI report configuration to indicate the number (N) of measured RS resources to be reported per report setting in a non-group-based report (e.g., indicated by a nofReportedRS IE in the CSI-ReportConfig IE). The value of the parameter (N) is less than or equal to a maximum value (N_max) which may be either 2 or 4 depending on the capability of the UE 3. When the field is absent the UE 3 applies a value of one. Where the number of measured RS is configured to be one, the reported L1-RSRP value is defined by a 7-bit value (e.g., corresponding to a L1-RSRP value in the range [-140, -44] dBm with 1dB step size). If the higher layer parameter is configured to be larger than one, or when group based beam reporting is enabled (e.g., if a higher layer parameter groupBasedBeamReporting is configured as 'enabled', or if a higher layer parameter groupBasedBeamReporting-r17 is configured) the UE 3 uses differential L1-RSRP based reporting. For differential based reporting, the largest measured value of L1-RSRP is quantised to a 7-bit value (e.g., in the range [-140, -44] dBm with 1dB step size) and other measured values of L1-RSRP are represented as differential L1-RSRP values, relative to the largest measured value, quantised to a 4-bit value. The differential L1-RSRP value is typically computed with 2 dB step size relative to the largest measured L1-RSRP value which is part of the same L1-RSRP reporting instance.

　　Moreover, when group based beam reporting is enabled (e.g., when the higher layer parameter groupBasedBeamReporting-r17 is configured in the CSI-ReportConfig IE), the UE 3 may also indicate the CSI Resource Set associated with the largest measured value of L1-RSRP, and for each group, CRI or SSBRI of the indicated CSI Resource Set may be present first.

　　A UE 3 may also be configured with a number of additional PCIs for L1-RSRP reporting of SSB resources (e.g., by means of an SSB-MTC-AddtionalPCI). When one or more additional PCIs are configured, a resource set configured for SSB resource related L1-RSRP CSI reporting (e.g., defined by a CSI-SSB-ResourceSet IE) may include a set of SSB indices and a set of PCI indices, where each SSB index is associated with a PCI index.

L1-SINR measurement and reporting
　　When one resource setting is configured, the resource retting (e.g., given by a higher layer parameter resourcesForChannelMeasurement) is for channel and interference measurement on NZP CSI-RS for L1-SINR computation. In this case the UE 3 may assume that the same single port one or more NZP CSI-RS resources (with density of three REs per RB) are used for both channel and interference measurements.

　　When two resource settings are configured, the first resource setting (e.g., given by a higher layer parameter resourcesForChannelMeasurement) is for channel measurement on an SSB or on NZP CSI-RS, and the second resource setting (e.g. given by either higher layer parameter csi-IM-ResourcesForInterference or higher layer parameter nzp-CSI-RS-ResourcesForInterference) is for interference measurement performed on CSI-IM or on a single port NZP CSI-RS (with density of three REs per RB), where each SSB or NZP CSI-RS resource for channel measurement is associated with one CSI-IM resource or one NZP CSI-RS resource for interference measurement by the ordering of the SSB or NZP CSI-RS resource for channel measurement and CSI-IM resource or NZP CSI-RS resource for interference measurement in the corresponding resource sets. The number of one or more SSBs or CSI-RS resources for channel measurement equals the number of CSI-IM resources or the number of NZP CSI-RS resources for interference measurement.

　　A UE 3 may apply the SSB, or a 'typeD' reference signal configured with a QCL type set to 'typeD' for the corresponding NZP CSI-RS resource for channel measurement, as the 'reference' reference signal for determining a 'type D' assumption for the corresponding CSI-IM resource, or the corresponding NZP CSI-RS resource for interference measurement, configured for one CSI reporting. A UE 3 may expect that the NZP CSI-RS resource set for channel measurement and the NZP-CSI-RS resource set for interference measurement, if any, are configured with a higher layer 'repetition' parameter (set to 'ON') indicating that resources within the resource set are transmitted with the same downlink spatial domain transmission filter.

Triggering/Activation of CSI Reporting for the possible CSI-RS Configurations
　　As explained above, the reporting configuration for CSI can be aperiodic (using PUSCH), periodic (using PUCCH) or semi-persistent (using PUCCH or DCI activated PUSCH). Similarly, the CSI-RS transmissions which are used to derive the CSI measurements can be periodic, semi-persistent, or aperiodic (e.g., an aperiodic CSI report can be generated based on periodic CSI-RS transmissions).

　　Periodic CSI reporting requires periodic CSI-RS transmission, both of which are configured and initiated by higher layer (e.g., RRC) signalling.

　　Semi-persistent CSI reporting on the PUCCH, for both semi-persistent and periodic CSI-RS transmission, are activated/deactivated by an activation command using an appropriate MAC control element (MAC CE) (e.g., a 'semi-persistent CSI reporting on PUCCH activation / deactivation' MAC CE). Semi-persistent CSI-RS transmission is also activated/deactivated by an activation command using an appropriate MAC CE (e.g., using a 'semi-persistent CSI-RS / CSI IM resource set activation / deactivation' MAC CE).

　　In contrast, semi-persistent CSI reporting on the PUSCH, for both semi-persistent and periodic CSI-RS transmission, is triggered using the CSI request field, as described earlier, in DCI (e.g., using DCI format 0_1 or DCI format 0_2) with cyclic redundancy bits scrambled appropriately (e.g., using a semi-persistent CSI radio network temporary identifier - SP-CSI-RNTI). Semi-persistent CSI reporting is not, however, supported for aperiodic CSI-RS transmission.

　　Aperiodic CSI reporting for periodic, semi-persistent, and aperiodic CSI-RS transmission are also all triggered using the CSI request field in the DCI (e.g., using DCI format 0_1 or DCI format 0_2) for semi-persistent, periodic, or aperiodic CSI-RS transmission.

　　Aperiodic CSI-RS transmission is also triggered using the CSI request field in the DCI (e.g., using DCI format 0_1 or DCI format 0_2).

　　The supported combinations of CSI Reporting configurations and CSI-RS Resource configurations, and how the CSI Reporting is triggered for each CSI-RS Resource configuration, is summarised below in Table 2.

L3 Measurement Reporting
　　A base station 5 can use dedicated higher layer (layer 3 - 'L3' / RRC) signalling to configure a UE 3 in an RRC connected mode to perform and report measurements. These measurements can be intra-frequency or inter-frequency measurements performed on SSBs or CSI-RS resources. The measurements may be at either 'beam' or 'cell' level where each beam level measurement is recorded for an SSB with a specific index, or from a CSI-RS resource with a specific identity. Cell level measurements may be derived from beam level measurements.

　　A measurement configuration typically includes one or more measurement identities. Each measurement identity links a reporting configuration to a measurement object (e.g., by including a pointer towards a reporting configuration and a pointer towards a measurement object). Multiple measurement identities can be used in a many to one manner to link a plurality of reporting configurations to the same measurement object and/or to link a single reporting configuration to a plurality of measurement objects. Each measurement identity is used by a UE 3 to identify which configured measurement a specific measurement result / set of measurement results relates to when reporting to the base station 5 (e.g., within a layer 3 (RRC) measurement report message). Accordingly, there is no need to explicitly indicate the measurement object or the reporting configuration.

　　A measurement object defines the object of the measurement by identifying the time and frequency location of the SSBs and/or CSI-RS resources to be measured. It also specifies corresponding subcarrier spacings. A single measurement object can specify both SSB and CSI-RS information. The reporting configuration is used for distinguishing between these two types of measurement resource. The measurement object can also specify a set of cell specific measurement offsets to make individual cells appear either more or less attractive for mobility purposes.

　　A report type indication in the reporting configuration provided by the base station 5 configures the measurement reporting to be of a specific type (e.g., a periodic, cell global identity (CGI), event triggered, conditional event triggered etc.).

　　For periodic reporting, the reporting configuration typically specifies: the reference signal type (SSB or CSI Reference Signal); a reporting interval (timing between reports); and a report amount (number of reports). A continuous stream of reports can be configured by setting the report amount to 'infinity' if required. The configuration also specifies 'cell level' and 'beam level' measurement quantities to be included and a maximum number of cells and maximum number of beams to be reported. The specified 'cell level' and 'beam level' measurement quantities can be any combination of RSRP, RSRQ and SINR as required.

　　For CGI type reporting the reporting configuration typically specifies the set of PCIs for which a UE 3 is required to decode and report the CGI. This type of reporting configuration can be used for neighbour addition and neighbour validation within the context of UE based Automatic Neighbour Relations (ANR).

　　For event triggered reporting the configuration information typically includes: parameters for a specific measurement reporting event; the reference signal type (SSB or CSI-RS) used to trigger the event, the number of reports to be sent after the event has triggered; and the time interval to be waited between those reports. The configuration may also specify the 'cell level' / 'beam level' measurement quantities to be included within each report and the maximum number of cells / beams to be reported. The specified 'cell level' and 'beam level' measurement quantities can be any combination of RSRP, RSRQ and SINR as required.

　　These L3 measurement reporting events include six core events, where one or more absolute thresholds, and/or offset values, may be used as follows:
-　　Event A1: Serving becomes better than absolute threshold;
-　　Event A2: Serving becomes worse than absolute threshold;
-　　Event A3: Neighbour becomes amount of offset better than primary cell (PCell) / special cell (PSCell) which may be a primary cell of a master cell group or a secondary cell group;
-　　Event A4: Neighbour becomes better than absolute threshold;
-　　Event A5: PCell/PSCell becomes worse than an absolute threshold (threshold 1) and neighbour/secondary cell (Scell) becomes better than another absolute threshold (threshold 2);
-　　Event A6: Neighbour becomes amount of offset better than SCell.
Each event is defined by at least one condition for initially triggering the event (referred to as an 'entry' condition) and at least one condition for triggering cancellation of the event (referred to as a 'leaving' condition).

　　By way of illustration, Fig. 4 is a measured (trigger) quantity vs. time graph illustrating triggering of event A5. In Fig. 4 (and for the other events also) the trigger quantity may be configured to be RSRP, RSRQ or SINR. In addition to one or more absolute thresholds or offset values, and as seen in Fig. 4, the events are also characterised by a time-to-trigger value (specifying a period of time following an event to wait before a measurement report is sent), and one or more hysteresis values (which effectively defines a delay or lag after a measurement exceeds (or drops below) a threshold before a corresponding entry or leaving event condition is triggered). The hysteresis values help to combat a repetitive cycle of an entry condition being met for an event and immediately followed by a leave condition being met for the same event, which can lead to undesirable 'ping-pong' type effects.

　　The reporting events also include a number of so-called 'conditional' events for supporting a 'conditional' event type of reporting (which are variations on a number of the core events) for supporting conditional reconfiguration as follows:
-　　Conditional Event A3: Conditional reconfiguration candidate becomes amount of offset better than PCell/PSCell;
-　　Conditional Event A4: Conditional reconfiguration candidate becomes better than absolute threshold; and
-　　Conditional Event A5: PCell/PSCell becomes worse than absolute threshold (threshold 1) AND Conditional reconfiguration candidate becomes better than another absolute threshold (threshold 2).

　　Conditional reconfiguration is a procedure in which the UE 3, rather than the network, can make a decision to perform handover when certain conditions are met. One such procedure, for example, may be a conditional handover (CHO) procedure in which a handover is executed by the UE 3 when one or more handover execution conditions are met. The UE 3 starts evaluating one or more execution conditions upon receiving a CHO configuration, and the UE 3 stops evaluating these execution conditions once a handover (either the CHO or another, network triggered, handover) is executed.

　　The report type indication provided to the UE 3, in the reporting configuration, may use any suitable information structure/element, for example, in accordance with standards defined by 3rd Generation Partnership Project (3GPP). A selected part of one such information structure/element is illustrated (for illustrative purposes only) in Fig. 5A and Fig. 5B. As seen in box (a) in Fig. 5A, the reporting configuration (ReportConfigNR IE) includes a report type indication (reportType IE) that includes, for each report type, a respective IE (which may include a set of one or more further IEs) for configuring that type of report. By way of example, part of an IE for configuring a 'conditional' event trigger reporting type (CondTriggerConfig-r16 IE) is shown in box (b) of Fig. 5B. As seen in box (b) of Fig. 5B, the illustrated part of the IE for configuring the conditional event trigger reporting type includes IEs for configuring parameters for two of the conditional events - conditional event A3 (condEventA3 IE), and conditional event A4 (condEventA4 IE), which mirror event A3 and event A4 respectively. The IE configuring conditional event A3 (condEventA3 IE) defines the offset, hysteresis and time to trigger values to be used (a3-Offset, hysteresis, and timeToTrigger IEs), whereas the IE configuring conditional event A4 (condEventA4 IE) defines the threshold, hysteresis, and time to trigger values to be used, and an indication of whether only cells in an allowed cell list are applicable (a4-threshold-r17, hysteresis-r17, timeToTrigger-r17, and useAllowedCellList-r17 IEs).

Transmission Configuration Indication (TCI) Framework
　　The communication system 1 employs a so-called transmission configuration indication (TCI) signalling framework.

　　The communication system 1 supports a per-channel/signal individual TCI framework in which a beam for a target channel/signal (e.g., PDSCH, PDCCH, CSI-RS) to be received by the UE 3 can be indicated by a TCI. The per-channel TCI consists, for example, of a source reference signal and an intended QCL type to be applied. For example, the base station 5 may schedule resources on a PDSCH to the UE 3 using DCI that indicates a TCI to be used for reception of the PDSCH. The UE 3 can then configure its beamforming parameters based on the indicated TCI and receive the PDSCH accordingly. For a PDCCH (or CSI-RS), a separate signal may be used for the TCI (independently of the PDSCH).

　　Although the individual per-channel beam indication framework has the benefit of the base station 5 being able to set and signal any independent beam reference per channel, the overall signalling overhead to control every target channel with a TCI can be significant. As those skilled in the art will be aware, a unified TCI framework has been standardised in Release 17 (Rel-17) 3GPP standards, that employs a common beam indication (TCI) across multiple channels/signals for DL and/or UL. The communication system 1 also supports this unified TCI framework. Specifically, the base station 5 and UE 3 are configured to employ a beam indication mechanism for LTM in the communication system 1 that is based on the unified TCI framework in the case that both serving cell and candidate cell support the unified TCI framework. Beneficially, however, the beam indication mechanism in the communication system 1 also supports the situation in which at least one of the serving cell and candidate cell supports only a legacy (e.g., Release 15) TCI framework.

　　Beneficially, the communication system 1 supports L1 inter-frequency measurement, and associated L1/L2 triggered measurement reporting to support, for example, LTM. The enhancements employed in communication system 1 can help to reduce associated handover delay / interruption when compared, for example, to handover procedures associated with traditional L3 triggered measurement reporting. Some of the enhancements support, for example, the possibility of downlink synchronisation with one or more candidate cells (where a 'candidate cell' is a candidate to be a target cell of an LTM cell switch procedure or the like), based on the SSBs transmitted in one or more candidate cells, before a cell switch command has been received (where the term 'cell switch' refers to a procedure of triggering a change of cells via LTM).

　　The mechanisms/features for supporting LTM take into consideration a number of aspects including, for example: the definition of one or more UE events for triggering L1 measurement reporting; the content/nature of the report/report container; the allocation/assignment of resource for such measurement reporting when triggered (and/or transmitted periodically, semi-persistently or aperiodically); the possibility of providing an indication, to the base station 5, of when a condition triggering the UE event has been met (and how such an indication may be provided); the possibility of defining one or more conditions for starting/stopping reporting; the content/reporting format of the measurement report (e.g., inclusion of the PCI, one or more reference signal (set) identifiers, one or more measurement results, and/or the like); the possibility of using/interaction with filtered L1 measurement results; the possibility of supporting simultaneous configuration of both UE event triggered and/or periodic/semi-persistence/aperiodic measurement reporting for LTM purposes, and how L1 measurement reporting for LTM proceeds when event triggered reporting is configured in conjunction with periodic/semi-persistence/aperiodic reporting; and/or the potential benefits of utilising L3 measurement.

　　The mechanisms/features for supporting LTM also take into consideration the possibility, for candidate cell measurement for LTM, to support measurement of SSB based L1-RSRP for intra-frequency measurement, and SSB based L1-RSRP for inter-frequency measurement. The mechanisms/features for supporting LTM also take into consideration the possibility of supporting L1-SINR SSB / CSI-RS based measurement and/or CSI-RS based L1-RSRP measurement.

　　The L1 measurement report for L1/L2 mobility described in more detail later may be reported via a MAC control element. Moreover, the L1 measurement report may be base station scheduled and/or may be UE initiated (where supported). It will, nevertheless, be appreciated that the L1 measurements for LTM may, alternatively or additionally, be reported via UCI on the PUCCH and/or the UCI part of the PUSCH. For example, a periodic report may be transmitted on a PUCCH, a semi-persistent report on a PUCCH or PUSCH, and an aperiodic report on the PUSCH.

　　The mechanisms/features for supporting LTM described herein also include potential enhancements for supporting inter-cell beam management (ICBM) (e.g., enhancements to the ICBM report format) to accommodate, for example, a reduction in the reporting overhead by, for example, appropriate selection of beams/cells per frequency (or across frequencies) to report.

User Equipment
　　Fig. 6 is a schematic block diagram illustrating the main components of a UE 3 as shown in Fig. 1.

　　As shown, the UE 3 has a transceiver circuit 31 that is operable to transmit signals to and to receive signals from a base station 5 via one or more antenna 33 (e.g., comprising one or more antenna elements). The UE 3 has a controller 37 to control the operation of the UE 3. The controller 37 is associated with a memory 39 and is coupled to the transceiver circuit 31. Although not necessarily required for its operation, the UE 3 might, of course, have all the usual functionality of a conventional UE 3 (e.g. a user interface 35, such as a touch screen / keypad / microphone / speaker and/or the like for, allowing direct control by and interaction with a user) and this may be provided by any one or any combination of hardware, software, and firmware, as appropriate. Software may be pre-installed in the memory 39 and/or may be downloaded via the telecommunications network or from a removable data storage device (RMD), for example.

　　The controller 37 is configured to control overall operation of the UE 3 by, in this example, program instructions or software instructions stored within memory 39. As shown, these software instructions include, among other things, an operating system 41, a communications control module 43, a measurement management module 45, and a measurement reporting module 47.

　　The communications control module 43 is operable to control the communication between the UE 3 and its one or more serving base stations 5 (and other communication devices connected to the base station 5, such as further UEs and/or core network nodes). The communications control module 43 is configured for the overall handling uplink communications via associated uplink channels (e.g. via a physical uplink control channel (PUCCH), random access channel (RACH), and/or a physical uplink shared channel (PUSCH)) including both dynamic and semi-static signalling (e.g., SRS). The communications control module 43 is also configured for the overall handling receipt of downlink communications via associated downlink channels (e.g. via a physical downlink control channel (PDCCH) and/or a physical downlink shared channel (PDSCH)) including both dynamic and semi-static signalling (e.g., CSI-RS, SSBs etc.). The communications control module 43 is responsible, for example, for determining the resources to be used by the UE 3, for determining how slots/symbols are configured (e.g., for UL, DL, flexible, full duplex communication, or the like), for determining which one or more bandwidth parts are configured for the UE 3, for determining how uplink transmissions should be encoded, etc.

　　It will be appreciated that the communications control module 43 may include a number of sub-modules (or 'layers') to support specific functionalities. For example, the communications control module 63 may include a PHY sub-module, a MAC sub-module, an RLC sub-module, a PDCP sub-module, an SDAP sub-module, an IP sub-module, an RRC sub-module, etc.

　　The measurement management module 45 is responsible, subject to overall control by the communications control module 43, for managing tasks related to the reception and measurement of downlink signals for measurement at the UE 3 such as reference signals and/or synchronisation signals (e.g., SSBs, CSI-RS, DMRS, and/or the like). The measurements are performed in accordance with measurement configuration information received from the base station 3 (e.g., information defining one or more CSI reporting configurations in conjunction with information configuring on or more CSI resources or sets of CSI resources). The measurement management module 45 is responsible for managing measurement for different purposes including, but not limited to, CSI reporting, L3 reporting, L1/L2 reporting of L1 event triggered, periodic and/or semi-persistent reporting, etc. The measurement signal management module 45 is also responsible for deriving propagation channel parameters (e.g., from DMRS) for the purposes of accurately decoding the PDSCH.

　　The measurement reporting module 47 is responsible for generating, and transmitting, appropriate reports based on the measurements (e.g., CSI reports carrying appropriate information such as CQI, PMI, RI, LI, CRI, SSBRI, L1-RSRP, L1-SINR, cri-RSRP, cri-SINR, L3 measurement reports, L1 event triggered, periodic and/or semi-persistent measurement reports, and/or the like depending on appropriate configuration from the base station 5). The measurement reporting module 47 is also responsible for determining when base station initiated activation/deactivation/triggering of measurement reporting related to the measurement signals has occurred (e.g., semi-persistent/aperiodic CSI-RS reporting or the like) and when entry / leaving conditions have been met for event triggered reporting.

Base Station
　　Fig. 7 is a schematic block diagram illustrating the main components of the base station 5 for the communication system 1 shown in Fig. 1. As shown, the base station 5 has a transceiver circuit 51 for transmitting signals to and for receiving signals from the communication devices (such as UEs 3) via one or more antenna 53 (e.g. a single or multi-panel antenna array / massive antenna), and a core network interface 55 (e.g. comprising the N2, N3 and other reference points/interfaces) for transmitting signals to and for receiving signals from network nodes in the core network 7. Although not shown, the base station 5 may also be coupled to other base stations via an appropriate interface (e.g. the so-called 'Xn' interface in NR). The base station 5 has a controller 57 to control the operation of the base station 5. The controller 57 is associated with a memory 59. Software may be pre-installed in the memory 59 and/or may be downloaded via the communication system 1 or from a removable data storage device (RMD), for example. The controller 57 is configured to control the overall operation of the base station 5 by, in this example, program instructions or software instructions stored within memory 59.

　　As shown, these software instructions include, among other things, an operating system 61, a communications control module 63, a measurement configuration management module 65, and a measurement report management module 67.

　　The communications control module 63 is operable to control the communication between the base station 5 and UEs 3 and other network entities that are connected to the base station 5. The communications control module 63 is configured for the overall control of the reception and decoding of uplink communications, via associated uplink channels (e.g. via a physical uplink control channel (PUCCH), a random-access channel (RACH), and/or a physical uplink shared channel (PUSCH)) including both dynamic and semi-static signalling (e.g., SRS). The communications control module 63 is also configured for the overall handling the transmission of downlink communications via associated downlink channels (e.g. via a physical downlink control channel (PDCCH) and/or a physical downlink shared channel (PDSCH)) including both dynamic and semi-static signalling (e.g., CSI-RS, SSBs etc.). The communications control module 63 is also responsible, for example, for determining and scheduling the resources to be used by the UE 3 for receiving in DL / transmitting in UL, for configuring slots/symbols appropriately (e.g., for UL, DL, flexible, full duplex communication, or the like), for configuring one or more bandwidth parts for the UE 3, and for providing related configuration signalling to the UE 3.

　　It will be appreciated that the communications control module 63 may include a number of sub-modules (or 'layers') to support specific functionalities. For example, the communications control module 63 may include a PHY sub-module, a MAC sub-module, an RLC sub-module, a PDCP sub-module, an SDAP sub-module, an IP sub-module, an RRC sub-module, etc.

　　The measurement configuration management module 65 is responsible, subject to overall control by the communications control module 63, for managing tasks related to the transmission of downlink signals for measurement at the UE 3 such as reference signals and/or synchronisation signals (e.g., SSBs, CSI-RS, DMRS, and/or the like) and the reception and measurement of uplink signals for measurement at the base station 5 (e.g., SRS). The measurement configuration management module 65 is also responsible for configuring appropriate resources for such measurement signals (e.g., CSI-RS resources) and for configuring UE reporting related to the measurement signals (e.g., CSI reports carrying appropriate information such as CQI, PMI, RI, LI, CRI, SSBRI, L1-RSRP, L1-SINR, cri-RSRP, cri-SINR, etc., L3 measurement reports, L1 event triggered, periodic and/or semi-persistent measurement reports, and/or the like). The measurement configuration management module 65 is also responsible for activating/deactivating/triggering, where appropriate, reporting related to the measurement signals (e.g., semi-persistent/aperiodic CSI-RS reporting or the like).

　　The measurement report management module 67 is responsible for reception, and handling of, reports based on the measurements (e.g., CSI reports carrying appropriate information such as CQI, PMI, RI, LI, CRI, SSBRI, L1-RSRP, L1-SINR, cri-RSRP, cri-SINR, L3 measurement reports, L1 event triggered, periodic and/or semi-persistent measurement reports, and/or the like).

Resource configuration and activation of L1 UE event triggered report
　　Possible mechanisms for activation/triggering of L1 event based reporting in the communication system 1 of Fig. 1 will now be described, by way of example only with reference to Table 3 and Table 4.

　　As explained above the CSI-RS transmissions can be configured as periodic, semi-persistent, or aperiodic and SSB transmissions are configured as periodic transmissions. L1 event based reporting, on the other hand, may be event based only or may be based on a combination of event triggered with periodic, semi-persistent, or aperiodic reporting. L1 event based measurement reports may be sent as UCI either in a PUCCH or a UCI part of a PUSCH.

　　Supported combinations of L1 measurement reporting configurations and SSB/CSI-RS configurations, and how L1 measurement reporting (e.g., for LTM) is activated/triggered for each SSB/CSI-RS configuration, for one possible mechanism for activation/triggering of L1 event based reporting, are summarised below in Table 3.

　　In the example of Table 3, for periodic CSI-RS / SSB transmissions, L1 event only triggered measurement reporting (on either PUCCH or PUSCH) is configured and initiated by higher layer (e.g., RRC) signalling (with no dynamic activation/deactivation). L1 event only triggered measurement reporting is not, however, supported for semi-persistent CSI-RS transmissions or aperiodic CSI-RS transmissions.

　　Similarly, for periodic CSI-RS / SSB transmissions, event triggered periodic L1 measurement reporting is configured and initiated by higher layer (e.g., RRC) signalling (with no dynamic activation/deactivation). Event triggered periodic L1 measurement reporting is not, however, supported for semi-persistent CSI-RS transmissions or aperiodic CSI-RS transmissions.

　　In contrast, for periodic CSI-RS / SSB transmissions and semi-persistent CSI-RS transmission, event triggered semi-persistent L1 measurement reporting on the PUCCH is activated/deactivated by an activation command using an appropriate MAC CE. Semi-persistent CSI-RS transmission may also be activated/deactivated by an activation command using an appropriate MAC CE. On the other hand, for periodic CSI-RS / SSB transmissions and for semi-persistent CSI-RS transmission, event triggered semi-persistent L1 measurement reporting on the PUSCH is triggered using DCI. Event triggered semi-persistent L1 measurement reporting is not, however, supported for aperiodic CSI-RS transmissions.

　　Event triggered aperiodic L1 measurement reporting, for periodic CSI-RS / SSB transmissions, semi-persistent CSI-RS transmissions and for aperiodic CSI-RS transmissions, are all triggered using DCI. Aperiodic CSI-RS transmission may also be triggered using DCI.

　　It will be appreciated that the activation/deactivation MAC CEs and triggering DCI used may be similar to those described for CSI reporting. However, dedicated L1 measurement activation/deactivation MAC CEs and triggering DCI used may be used.

　　Supported combinations of L1 measurement reporting configurations and SSB/CSI-RS configurations, and how L1 measurement reporting (e.g., for LTM) is activated/triggered for each SSB/CSI-RS configuration, for another possible mechanism for activation/triggering of L1 event based reporting, are summarised below in Table 4.

　　In the example of Table 4, for periodic CSI-RS / SSB transmissions, semi-persistent CSI-RS transmissions and for aperiodic CSI-RS transmissions, L1 event only triggered measurement reporting on PUCCH is activated/deactivated by an activation command using an appropriate MAC CE. L1 event only triggered measurement reporting on PUSCH is, on the other hand, triggered using DCI.

　　For periodic CSI-RS / SSB transmissions, event triggered periodic L1 measurement reporting is configured and initiated by higher layer (e.g., RRC) signalling (with no dynamic activation/deactivation). Event triggered periodic L1 measurement reporting is not, however, supported for semi-persistent CSI-RS transmissions or aperiodic CSI-RS transmissions.

Two stage event triggered measurement reporting
　　Other possible mechanisms for L1 event based reporting in the communication system 1 of Fig. 1, and variations on the mechanism, will now be described, by way of example only with reference to Figs. 7 to 10. It will be appreciated that while the 'two stage' mechanisms described may be implemented as an alternative to those discussed above with reference to Table 3 and Table 4 they are not mutually exclusive.

Generalised two stage event triggered measurement reporting
　　Fig. 8 is a simplified sequence diagram illustrating a possible generalised two stage mechanism for L1 event based measurement reporting and Figs. 9 to 11 are each a simplified sequence diagram illustrating a more specific two stage mechanism for L1 event based measurement reporting based on the general mechanism illustrated in Fig. 8.

　　As seen in Fig. 8, a base station 5 determines a measurement configuration for L1 measurements for LTM. The measurement configuration may include, for example, a resource configuration, a reporting configuration for L1 measurements, and information defining one or more L1 events (at S810). The configurations may include, for example, a configuration of one or more resources or sets of resources that will be used for transmission of signals (e.g., CSI-RS and/or SSBs) for measurement and associated triggering of one or more L1 events, a configuration of the quantity/quantities to be reported, a configuration of L1 parameters defining one or more L1 event conditions, and possible other measurement reporting parameters (as described elsewhere in this document).

　　The base station 5 also determines one or more allocations of PUCCH resources for use by the UE to transmit in the UL (at S812). The allocations may include PUCCH resources for transmission of one or more scheduling requests (SRs) and/or may include one or more dedicated periodic PUCCH resources for transmission of an indication that an L1 measurement is available.

　　It will be appreciated while the determinations made at S810 and S812 are shown in a particular sequential order they may be made in any order or concurrently.

　　The base station 5 sends, at S814, configuration signalling to the UE 3. The configuration signalling includes information identifying one or more PUCCH resource allocations determined at S812 and information identifying the measurement configuration determined at S810. The configuration signalling may use any appropriate signalling protocol, for example the RRC protocol (e.g., RRC setup, (re)configuration, and/or resumption signalling) and may comprise one or more messages.

　　The UE 3 performs the configured L1 measurements (e.g., L1-RSRP and/or L1-SINR) on the signals (e.g., SSB / CSI-RS) transmitted using one or more resources / resource sets configured for measurement and monitors for triggering of an L1 event (at S816).

　　When an L1 event has been triggered (at S816) and a measurement report is ready (at S819), the UE 3 sends (at S820) an initial indication that an L1 measurement report is available using one or more allocated PUCCH resources (e.g., PUCCH resources for the SR or dedicated periodic PUCCH resources for sending such an indication).

　　Upon receiving the initial indication, the base station 5 schedules (at S822) one or more dynamic PUSCH resources for the UE to send the L1 measurement report in the UL. The base station 5 signals the scheduled dynamic one or more UL (e.g. PUSCH) resources to the UE 3 (at S824) using appropriate signalling (e.g., DCI transmitted on the PDCCH using DCI format 0_0/0_1 or the like).

　　The UE 3 then sends the measurement report to the base station 5 (at S826) in the UL (e.g. PUSCH) using one or more scheduled resources.

　　Accordingly, the base station 5 can make a decision on whether or not to initiate an LTM mobility procedure (e.g., a change of cell or the like) based on the content of the measurement report.

　　As described in more detail later, the content of the measurement report may, for example, be provided be means of a dedicated L1 measurement reporting MAC CE (e.g., an 'L1 Measurement Report' MAC CE). An L1 Measurement Report MAC Control Element may, for example, be identified by a MAC protocol data unit (PDU) sub-header with a specific logical channel identifier (LCID). As described in more detail later, the MAC CE may have a fixed size or a dynamic size depending on the content within the L1 measurement report. Nevertheless, while the use of a MAC CE provides some benefit it will be appreciated that, alternatively or additionally, provision could be made to report the L1 measurements using UCI on the PUCCH or the UCI part of the PUSCH.

Legacy SR based two stage event triggered measurement reporting
　　Fig. 9 is a simplified sequence diagram illustrating a possible scheduling request based two stage mechanism for L1 event based measurement reporting. The procedure is similar to the generalised mechanism illustrated in Fig. 8 but beneficially takes advantage of a number of legacy features.

　　While not shown in Fig. 9 for reasons of simplicity, as with the procedure in Fig. 8, the base station 5 may initially determine a measurement configuration for L1 measurements for LTM. The measurement configuration may include, for example, a resource configuration, a reporting configuration for L1 measurements, and information defining one or more L1 events. The configurations may include, for example, a configuration of one or more resources or sets of resources that will be used for transmission of signals (e.g., CSI-RS and/or SSBs) for measurement and associated triggering of one or more L1 events, a configuration of the quantity/quantities to be reported, a configuration of L1 parameters defining one or more L1 event conditions, and possible other measurement reporting parameters (as described elsewhere in this document).

　　Similarly, as with the procedure in Fig. 8, the base station 5 in Fig. 9 may also determine one or more allocations of PUCCH resources for use by the UE to transmit in the UL. The allocations may include, in this example, legacy SR PUCCH resources for transmission of one or more scheduling requests.

　　The base station 5 sends, at S914, configuration signalling to the UE 3. The configuration signalling includes information identifying one or more PUCCH resource allocations and information identifying the measurement configuration. The configuration signalling may use any appropriate signalling protocol, for example the RRC protocol (e.g., RRC setup, (re)configuration, and/or resumption signalling) and may comprise one or more messages.

　　The UE 3 performs the configured L1 measurements (e.g., L1-RSRP and/or L1-SINR) on the signals (e.g., SSB / CSI-RS) transmitted using one or more resources / resource sets configured for measurement and monitors for triggering of an L1 event (at S916).

　　When an L1 event has been triggered (at S916), and a measurement report MAC CE is ready (at S919), the UE 3 determines whether there are any PUSCH resources available (at S921).

　　If PUSCH resources are not available at S921, then the UE 3 triggers a scheduling request procedure (at 823) and determines (at S925) whether there are any PUCCH resources available for an SR PUCCH transmission.

　　If SR PUCCH resources are available at S925, then the UE 3 sends, in this example, a scheduling request using one or more of the available SR PUCCH resources (at S920). If SR PUCCH resources are not available at S925, then the UE 3 triggers, in this example, a random access channel (RACH) procedure (at S920) to obtain a grant of resources for transmission in the uplink.

　　Upon receiving the scheduling request, or as part of the RACH procedure, the base station 5 determines (at S922) one or more uplink (e.g. PUSCH) resources for the UE to send the L1 measurement report in the UL. The base station 5 signals one or more scheduled UL resources to the UE 3 (at S924) using appropriate signalling (e.g., DCI transmitted on the PDCCH using DCI format 0_0/0_1 in the case of a scheduling request, a random access response (RAR) message in the case of a RACH procedure, or the like).

　　Following receipt of a UL grant at S924, or in the event that PUSCH resources are found to be available at S921, then the UE 3 sends the measurement report to the base station 5 (at S926) in the UL (e.g. PUSCH) using one or more scheduled/available resources.

　　As described above and in more detail later, the content of the measurement report may, for example, be provided be means of a dedicated L1 measurement reporting MAC CE (e.g., an 'L1 Measurement Report' MAC CE). Nevertheless, provision could be made to report the L1 measurements using UCI on the PUCCH or the UCI part of the PUSCH.

Dedicated SR PUCCH resource based two stage event triggered measurement reporting
　　Fig. 10 is a simplified sequence diagram illustrating another possible two stage mechanism for L1 event based measurement reporting. Like the procedure of Fig. 9, this procedure uses SR PUCCH resources although in this case the base station 5 allocates SR type periodic PUCCH resources dedicated to L1 event triggered measurement reporting.

　　As seen in Fig. 10, a base station 5 determines a measurement configuration for L1 measurements for LTM. The measurement configuration may include, for example, a resource configuration, a reporting configuration for L1 measurements, and information defining one or more L1 events (at S1010). The configurations may include, for example, a configuration of one or more resources or sets of resources that will be used for transmission of signals (e.g., CSI-RS and/or SSBs) for measurement and associated triggering of one or more L1 events, a configuration of the quantity/quantities to be reported, a configuration of L1 parameters defining one or more L1 event conditions, and possible other measurement reporting parameters (as described elsewhere in this document).

　　The base station 5 also determines (at S1012) one or more allocations of L1 measurement report dedicated SR type PUCCH resources for use by the UE to transmit the L1 measurement report indication in the UL. In this example, the allocation is in addition to any allocation of PUCCH resources allocated for an SR to support a legacy SR procedure.

　　It will be appreciated while the determinations made at S1010 and S1012 are shown in a particular sequential order they may be made in any order or concurrently.

　　The base station 5 sends, at S1014, configuration signalling to the UE 3. The configuration signalling includes information identifying one or more PUCCH resource allocations determined at S1012 and information identifying the measurement configuration determined at S1010. The configuration signalling may use any appropriate signalling protocol, for example the RRC protocol (e.g., RRC setup, (re)configuration, and/or resumption signalling) and may comprise one or more messages.

　　The UE 3 performs the configured L1 measurements (e.g., L1-RSRP and/or L1-SINR) on the signals (e.g., SSB / CSI-RS) transmitted using one or more resources / resource sets configured for measurement and monitors for triggering of an L1 event (at S1016).

　　When an L1 event has been triggered (at S1016) and a measurement report is ready (at S1019), the UE 3 sends (at S1020) an initial indication that an L1 measurement report is available using one or more allocated L1 measurement report dedicated SR type PUCCH resources. This indication may, for example, be a single bit based indication (e.g., a flag) using one of the allocated PUCCH resources in a given transmission occasion.

　　Upon receiving the initial indication, the base station 5 schedules (at S1022) appropriate (e.g., PUSCH) resources for the UE to send the L1 measurement report in the UL. The base station 5 signals one or more scheduled resources to the UE 3 (at S1024) using appropriate signalling (e.g., DCI transmitted on the PDCCH using DCI format 0_0/0_1 or the like).

　　The UE 3 then sends the measurement report to the base station 5 (at S1026) in the UL (e.g. PUSCH) using one or more scheduled resources. As described in more detail later, the content of the measurement report may, for example, be provided be means of a dedicated L1 measurement reporting MAC CE (e.g., an 'L1 Measurement Report' MAC CE). In this example the size of the MAC CE used to carry the L1 measurement report is fixed and so the scheduled resources are selected to be sufficient (i.e., of sufficient capacity / size) to match (or exceed) the fixed size of the MAC CE used to carry the L1 measurement report. It will be appreciated, however, that the size of the MAC CE may be variable and the L1 measurement indication may, as described in more detail with reference to Fig. 11 below, may be configured to indicate the size of MAC CE / measurement report that is to be sent (or an amount of resources required to send the measurement report).

Dedicated type of PUCCH resource based two stage event triggered measurement reporting
　　Fig. 11 is a simplified sequence diagram illustrating another possible two stage mechanism for L1 event based measurement reporting. In this example, the procedure uses a new type of periodic PUCCH resources PUCCH resources that are dedicated to L1 event triggered measurement reporting rather than using dedicated SR type PUCCH resources.

　　As seen in Fig. 11, a base station 5 determines a measurement configuration for L1 measurements for LTM. The measurement configuration may include, for example, a resource configuration, a reporting configuration for L1 measurements, and information defining one or more L1 events (at S1110). The configurations may include, for example, a configuration of one or more resources or sets of resources that will be used for transmission of signals (e.g., CSI-RS and/or SSBs) for measurement and associated triggering of one or more L1 events, a configuration of the quantity/quantities to be reported, a configuration of L1 parameters defining one or more L1 event conditions, and possible other measurement reporting parameters (as described elsewhere in this document).

　　The base station 5 also determines (at S1112) one or more allocations of an L1 measurement report dedicated type of PUCCH resources specifically for use by the UE 3 to transmit the L1 measurement report indication in the UL.

　　It will be appreciated while the determinations made at S1110 and S1112 are shown in a particular sequential order they may be made in any order or concurrently.

　　The base station 5 sends, at S1114, configuration signalling to the UE 3. The configuration signalling includes information identifying one or more PUCCH resource allocations determined at S1112 and information identifying the measurement configuration determined at S1110. The configuration signalling may use any appropriate signalling protocol, for example the RRC protocol (e.g., RRC setup, (re)configuration, and/or resumption signalling) and may comprise one or more messages.

　　The UE 3 performs the configured L1 measurements (e.g., L1-RSRP and/or L1-SINR) on the signals (e.g., SSB / CSI-RS) transmitted using one or more resources / resource sets configured for measurement and monitors for triggering of an L1 event (at S1116).

　　When an L1 event has been triggered (at S1116) and a measurement report is ready (at S1119), the UE 3 sends (at S1120) an initial indication that an L1 measurement report is available using one or more allocated L1 measurement report dedicated type of PUCCH resources. This indication may, for example, comprise a plurality of bits (e.g., two bits) using PUCCH resources allocated by the network. For example, in the case of a two-bit indication the different combinations of two bits (00, 01,10, 11) may each represent a different possible MAC CE / measurement report size that is to be sent (or an amount of resources required to send the measurement report). Specifically, when there is a measurement report available, the UE 3 calculates the size of the L1 measurement report / MAC CE that will be needed to carry the L1 measurement report, and sends a corresponding indication (i.e., multiple-bit based indication) over one of the allocated PUCCH resources in a given transmission occasion.

　　It will be appreciated that a table mapping the multiple-bit based indication to the actual MAC CE / L1 measurement report size may be defined and stored at the UE3 / base station 5. This mapping table may be fixed and preconfigured or may be (re)configurable (e.g. to represent different possible ranges of MAC CE sizes).

　　Upon receiving the initial indication, the base station 5 schedules (at S1122) appropriate (e.g., PUSCH) resources for the UE to send the L1 measurement report in the UL. The base station 5 signals one or more scheduled resources to the UE 3 (at S1124) using appropriate signalling (e.g., DCI transmitted on the PDCCH using DCI format 0_0/0_1 or the like).

　　The UE 3 then sends the measurement report to the base station 5 (at S1126) in the UL (e.g. PUSCH) using one or more scheduled resources. As described in more detail later, the content of the measurement report may, for example, be provided be means of a dedicated L1 measurement reporting MAC CE (e.g., an 'L1 Measurement Report' MAC CE). In this example the size of the MAC CE used to carry the L1 measurement report is variable and so the scheduled resources are selected to be sufficient (i.e., of sufficient capacity / size) to match (or exceed) the variable size of the MAC CE used to carry the L1 measurement report (and indicated by the indication that an L1 measurement report is available). It will be appreciated, however, that the size of the MAC CE / measurement report may be fixed and the L1 measurement indication may, as described in more detail with reference to Fig. 10 above, be a fixed (invariable) indication (e.g. single bit / flag).

MAC-CE based L1 measurement report
　　As explained above, the L1 measurement report may be transmitted using a MAC CE.

　　In one example, the L1 measurement report MAC CE includes, for each measurement result reported, an identifier associated with the target of the measurement (e.g., a PCI associated with the TRP / cell / beam to which the result relates), information identifying the reference signal to which the result relates (e.g., RS ID), and the measurement report.

　　For each serving cell and/or candidate cell to which one or more reported measurement results relate, the MAC CE may include, for example, one or more of the following (where appropriate):
-　　an indication of whether each reported result / set of results is at a cell level or at a beam level (e.g., if both beam level and cell level filtering type results are present) (an appropriate length for this cell level/beam level indicator field may, for example, be 1 bit);
-　　a measurement quantity for each measurement result (e.g., whether the measured quantity was L1-RSRP or L1-SINR);
-　　an indication of the number of reported beams (e.g., for any measurement results that are for beam level reporting) (an appropriate length for this field may, for example, be 2 bit);
-　　a cell identity for each measurement result / set of measurement results indicating the identity (serving cell identity or candidate cell identity) of the serving cell or candidate cell for which the measurement result applies (an appropriate length for this cell identity field may, for example, be 5 bits for each cell ID);
-　　a resource set identifier (e.g., for an SSB/CSI-RS resource set) for the/each measured resource set configured for L1 mobility measurement reporting in the identified cell (an appropriate length for this field may, for example, be 6 bits);
-　　a set of one or more measurement results for each cell:
set of one or more measurement results for each cell:
　　-- Each reported L1-RSRP value may, for example, be an absolute (e.g., 7-bit) value, or differential reporting may be used in which one or more L1-RSRP values are reported as differential (e.g., 4-bit) values relative to another reported 'reference' absolute (e.g. 7-bit) value of L1-RSRP (e.g., the reference value may be the highest (or lowest) reported L1-RSRP).
　　-- Moreover, each reported L1-SINR value may, for example, be an absolute (e.g., 7-bit) value, or differential reporting may be used in which one or more L1-SINR values are reported as differential (e.g., 4-bit) values relative to another reported 'reference' absolute (e.g. 7-bit) value of L1-SINR (e.g., the reference value may be the highest (or lowest) reported L1-SINR).
-　　a respective measurement identifier for each reported measurement result / set of measurement results (an appropriate length for this field may, for example, be 6 bits); and/or
-　　an indication of the number of candidate cells reported (an appropriate length for this field may, for example, be 3 bits).

Definition of one or more L1 Events for triggering L1 Measurement Reporting
　　While events for triggering L1 measurement reporting could be configured to correspond closely with the L3 measurement reporting events, for LTM there are benefits in supporting a reduced number of event types (compared to the L3 measurement reporting events) with simplified event trigger conditions (e.g., without specifying hysteresis.

　　For example, in one implementation, the following dedicated reporting events may be configured for L1 measurement reporting to support LTM:
-　　Event Type 1: Candidate cell becomes better than (is above) a threshold
-　　Event Type 2: Candidate cell becomes an offset better than (greater than) serving cell

　　The events can be configured by the base station 5, via a reporting configuration sent to the UE 3 - for example as part of a CSI reporting configuration (e.g., similar to that described above for CSI reporting) but with L1 reporting events defined (e.g., in a similar manner to that described above for the L3 measurement reporting).

　　The measurements may be configured for time domain and/or cell-level filtering (e.g., L1 filtering) to introduce a certain amount of averaging and, in this case, the reporting configuration may include an IE/field for indicating the type of filtering to be applied. For example, a two bit (e.g., 00,01,10,11) or an enumerated (e.g., filtering Type {None, Time domain, Cell level, Time domain & Cell level}) IE/field may be used to indicate the four different possibilities. For time domain filtering/averaging an averaging window (time period) size may be specified/configured to the UE 3.

　　As described above the base station 5 may provide the UE 3 with a simultaneous configuration of both UE event triggered and any of periodic, semi-persistent and/or aperiodic reporting. In the event of such a configuration, the measurement reporting may proceed in a number of different ways.

　　For example, a periodic, semi-persistent and/or aperiodic measurement report in accordance with an associated reporting configuration may include both the periodic, semi-persistent and/or aperiodic type of measurement results and any measurement results for which the event trigger has been satisfied.

　　In another example, only measurement results (e.g., in accordance with a periodic/semi-persistent reporting configuration) for which the specified triggering event threshold has been met, will be sent in a periodic/semipersistent report with a periodicity as specified in a periodic reporting configuration.

　　In another example, upon measurement results satisfying a specified event trigger, any periodic/semi-persistent reporting in accordance with the reporting configuration will start to be sent (e.g., until the event trigger is no longer satisfied, or the reporting is stopped as a result of another condition being met or in accordance with some other mechanism). For example, one or more measurement thresholds may be configured for events for starting and/or for stopping of periodic/semi-persistent L1 measurement reporting.

　　These start/stop thresholds may be based on L3 type measurement results (e.g., results of L3 filtered measurements of RSRP/RSRQ/SINR) for events for LTM that correspond to L3 type events (e.g., type A3 and type A4 or type conditional A3 and type conditional A4). Alternatively, the start/stop thresholds may be based on L1 type measurement results (without L3 filtering but which may be L1/L2 filtered measurement results), for example for specifically defined (e.g., Type 1/Type 2) L1 measurement reporting events.

　　The thresholds may be configured as part of a report type configuration provided to the UE 3 (e.g., in the CSI reporting configuration) and may use any suitable information structure/element. A selected part of one such information structure/element is illustrated (for illustrative purposes only) in Fig. 12A and Fig. 12B. As seen in box (a) in Fig. 12A, a report configuration type indication (reportConfigType IE) is shown that defines, for a periodic report configuration (using a 'periodic' IE), a periodicity and slot offset of a slot configuration for the report (reportSlotConfig IE defined by the CSI-ReportPeriodicityAndOffset IE) and an associated list (pucch-CSI-ResourceList) indicating, for each BWP, (1..maxNrofBWPs) which PUCCH resource (pucch-CSI-Resource) to use for reporting on the PUCCH. In this example, the configuration also includes information for configuring the event trigger (eventTriggeredL1 / EventTriggerConfigL1).

　　Part of a possible IE for configuring a 'conditional' event trigger reporting type for an L1 event (e.g., for supporting LTM) is shown in box (b) of Fig. 12B (CondTriggerConfigL1-r18 IE). As seen in box (b) of Fig. 12B, the illustrated part of the IE for configuring the conditional event trigger reporting type includes IEs for configuring parameters for two conditional L1 events for supporting LTM - a conditional A3 like event (condL1EventA3-r18 IE), and a conditional A4 like event (condL1EventA4-r18 IE), which mirror event A3 and event A4 respectively. The IE configuring the conditional A3 like L1 event (condL1EventA3-r18 IE) defines the offset and time to trigger values to be used (a3-Offset-L1 and timeToTriggerL1-r18 IEs), whereas the IE configuring the A4 like conditional L1 event (condL1EventA4-r18 IE) defines the threshold and time to trigger values to be used (a4-thresholdL1-r18 and timeToTrigger-L1-r18 IEs).

Inter-cell beam management (ICBM)
　　A number of enhancements for supporting inter-cell beam management (ICBM) will now be described in more detail, by way of example with reference to Fig. 13, which illustrates a method that may be performed by a UE 3 for selecting a subset of measurement results to report.

　　As seen in Fig. 13, the UE 3 ranks (at S1310) the beams/cells based, for example, on the measured values (for example from highest to lowest). It will be appreciated that, in the case of event triggered reporting, the ordered measurement results may include only measurement results fulfilling the reporting criteria defined for the corresponding event.

　　The UE 3 then selects one beam per frequency, and then per cell, for reporting until all beams have been reported or the maximum number of reportable beams has been reached.

　　Beneficially, therefore, this technique helps to reduce the reporting overhead by appropriate beams/cell selection per frequency, or across frequencies, for reporting.

　　It will be appreciated, that the reporting of measurement results may be subject to a specific threshold (which may be configured by the network) with only measurement values above the specified threshold being reported.

　　It will be appreciated that the selection order may be based on a priority ranking for the cell/carrier. Alternatively, or additionally, a maximum number of beams to be reported, and/or number of cells to be reported, per carrier may be (pre)configured (and the selection of beams for reporting may be subject to the maximum number of beams and/or maximum number of cells per carrier). Alternatively, or additionally, a maximum number of beams to be reported per cell may be (pre)configured (and the selection of beams for reporting may be subject to the maximum number of beams to be reported per cell). In addition, only a subset of measurement results may be reported, for example only those measurement values above a specified threshold may be reported.

　　Beneficially, the report may comprise a flexible size beam report. For example, a flexible size report may be sent using two-part uplink control information (e.g., in which the first part includes results for one or more best beams/cells and indicates the total number (e.g., Nbeam) of reported beams/cells, and the second part includes the results for the rest of the beams/cells.

　　Beneficially, the maximum number of reported beams may be enhanced to increase the maximum number of reported beams (which has historically been four for ICBM). For example, in a communication system in which the maximum number of reported beams in a measurement report has been increased from four, the maximum number may be configurable. For example, the maximum number may be configured to be an integer multiple of four (i.e., N x 4), or of another appropriate integer value, where N is configurable. N may have a default value (e.g., N=1, or N=2 such that four beams for each of two cells/carriers or two beams for each of four cells/carriers can be reported).

　　It will also be appreciated that the measurement report in accordance with the ICBM reporting format (or other reporting format) may include measurement results arising from inter-frequency measurement.

Beam indication for LTM in the context of a serving cell / candidate cell that supports a legacy TCI framework.
　　As explained above, while the beam indication mechanism for LTM used in the communication system 1 is based on the unified TCI framework, the beam indication mechanism in the communication system 1 also supports the situation in which at least one of the serving cell and candidate cell supports only a legacy (e.g., Release 15) TCI framework.

　　Specifically, referring to Fig. 14 which is a simplified sequence diagram of part of a procedure for LTM, when indicating a TCI state in a cell switch command for LTM, the indicated TCI state in cell switch command will be for SSB beam by default.

　　However, in one example, support for a legacy framework may be provided by means of a further beam indication (e.g., for CSI-RS, CORESET, PDSCH, PUCCH, PUSCH) that may be sent, after the cell switch command, for any candidate cells that only support a legacy TCI framework as illustrated at S1410.

　　In another example, in addition to a TCI state for a target cell, separate TCI states for each channel may also be included in the cell switch command as illustrated at S1412.

Modifications and Alternatives
　　A detailed embodiment has been described above. As those skilled in the art will appreciate, a number of modifications and alternatives can be made to the above embodiments whilst still benefiting from the disclosures embodied therein.

　　It will be appreciated, for example, that whilst cellular communication generation (2G, 3G, 4G, 5G, 6G etc.) specific terminology may be used, in the interests of clarity, to refer to specific communication entities, the technical features described for a given entity are not limited to devices of that specific communication generation. The technical features may be implemented in any functionally equivalent communication entity regardless of any differences in the terminology used to refer to them.

　　In the above description, the UEs and the base station are described for ease of understanding as having a number of discrete functional components or modules. Whilst these modules may be provided in this way for certain applications, for example where an existing system has been modified to implement the disclosure, in other applications, for example in systems designed with the inventive features in mind from the outset, these modules may be built into the overall operating system or code and so these modules may not be discernible as discrete entities.

　　In the above embodiments, a number of software modules were described. As those skilled in the art will appreciate, the software modules may be provided in compiled or un-compiled form and may be supplied to the base station or to the UE as a signal over a computer network, or on a recording medium. Further, the functionality performed by part, or all of this software may be performed using one or more dedicated hardware circuits. However, the use of software modules is preferred as it facilitates the updating of the base station or the UE in order to update their functionalities.

　　Each controller may comprise any suitable form of processing circuitry including (but not limited to), for example: one or more hardware implemented computer processors; microprocessors; central processing units (CPUs); arithmetic logic units (ALUs); input/output (IO) circuits; internal memories / caches (program and/or data); processing registers; communication buses (e.g. control, data and/or address buses); direct memory access (DMA) functions; hardware or software implemented counters, pointers and/or timers; and/or the like. Various other modifications will be apparent to those skilled in the art and will not be described in further detail here.

　　The base station may comprise a 'distributed' base station having a central unit 'CU' and one or more separate distributed units (DUs).

　　The User Equipment (or "UE", "mobile station", "mobile device" or "wireless device") in the present disclosure is an entity connected to a network via a wireless interface.

　　It should be noted that the present disclosure is not limited to a dedicated communication device and can be applied to any device having a communication function as explained in the following paragraphs.

　　The terms "User Equipment" or "UE" (as the term is used by 3GPP), "mobile station", "mobile device", and "wireless device" are generally intended to be synonymous with one another, and include standalone mobile stations, such as terminals, cell phones, smart phones, tablets, cellular IoT devices, IoT devices, and machinery. It will be appreciated that the terms "mobile station" and "mobile device" also encompass devices that remain stationary for a long period of time.

　　A UE may, for example, be an item of equipment for production or manufacture and/or an item of energy related machinery (for example equipment or machinery such as: boilers; engines; turbines; solar panels; wind turbines; hydroelectric generators; thermal power generators; nuclear electricity generators; batteries; nuclear systems and/or associated equipment; heavy electrical machinery; pumps including vacuum pumps; compressors; fans; blowers; oil hydraulic equipment; pneumatic equipment; metal working machinery; manipulators; robots and/or their application systems; tools; molds or dies; rolls; conveying equipment; elevating equipment; materials handling equipment; textile machinery; sewing machines; printing and/or related machinery; paper converting machinery; chemical machinery; mining and/or construction machinery and/or related equipment; machinery and/or implements for agriculture, forestry and/or fisheries; safety and/or environment preservation equipment; tractors; precision bearings; chains; gears; power transmission equipment; lubricating equipment; valves; pipe fittings; and/or application systems for any of the previously mentioned equipment or machinery etc.).

　　A UE may, for example, be an item of transport equipment (for example transport equipment such as: rolling stocks; motor vehicles; motorcycles; bicycles; trains; buses; carts; rickshaws; ships and other watercraft; aircraft; rockets; satellites; drones; balloons etc.).

　　A UE may, for example, be an item of information and communication equipment (for example information and communication equipment such as: electronic computer and related equipment; communication and related equipment; electronic components etc.).

　　A UE may, for example, be a refrigerating machine, a refrigerating machine applied product, an item of trade and/or service industry equipment, a vending machine, an automatic service machine, an office machine or equipment, a consumer electronic and electronic appliance (for example a consumer electronic appliance such as: audio equipment; video equipment; a loud speaker; a radio; a television; a microwave oven; a rice cooker; a coffee machine; a dishwasher; a washing machine; a dryer; an electronic fan or related appliance; a cleaner etc.).

　　A UE may, for example, be an electrical application system or equipment (for example an electrical application system or equipment such as: an x-ray system; a particle accelerator; radio isotope equipment; sonic equipment; electromagnetic application equipment; electronic power application equipment etc.).

　　A UE may, for example, be an electronic lamp, a luminaire, a measuring instrument, an analyzer, a tester, or a surveying or sensing instrument (for example a surveying or sensing instrument such as: a smoke alarm; a human alarm sensor; a motion sensor; a wireless tag etc.), a watch or clock, a laboratory instrument, optical apparatus, medical equipment and/or system, a weapon, an item of cutlery, a hand tool, or the like.

　　A UE may, for example, be a wireless-equipped personal digital assistant or related equipment (such as a wireless card or module designed for attachment to or for insertion into another electronic device (for example a personal computer, electrical measuring machine)).

　　A UE may be a device or a part of a system that provides applications, services, and solutions described below, as to "internet of things (IoT)", using a variety of wired and/or wireless communication technologies.

　　Internet of Things devices (or "things") may be equipped with appropriate electronics, software, sensors, network connectivity, and/or the like, which enable these devices to collect and exchange data with each other and with other communication devices. IoT devices may comprise automated equipment that follow software instructions stored in an internal memory. IoT devices may operate without requiring human supervision or interaction. IoT devices might also remain stationary and/or inactive for a long period of time. IoT devices may be implemented as a part of a (generally) stationary apparatus. IoT devices may also be embedded in non-stationary apparatus (e.g. vehicles) or attached to animals or persons to be monitored/tracked.

　　It will be appreciated that IoT technology can be implemented on any communication devices that can connect to a communications network for sending/receiving data, regardless of whether such communication devices are controlled by human input or software instructions stored in memory.

　　It will be appreciated that IoT devices are sometimes also referred to as Machine-Type Communication (MTC) devices or Machine-to-Machine (M2M) communication devices. It will be appreciated that a UE may support one or more IoT or MTC applications. Some examples of MTC applications are listed in the following table. This list is not exhaustive and is intended to be indicative of some examples of machine type communication applications.

　　Applications, services, and solutions may be an MVNO (Mobile Virtual Network Operator) service, an emergency radio communication system, a PBX (Private Branch eXchange) system, a PHS/Digital Cordless Telecommunications system, a POS (Point of sale) system, an advertise calling system, an MBMS (Multimedia Broadcast and Multicast Service), a V2X (Vehicle to Everything) system, a train radio system, a location related service, a Disaster/Emergency Wireless Communication Service, a community service, a video streaming service, a femto cell application service, a VoLTE (Voice over LTE) service, a charging service, a radio on demand service, a roaming service, an activity monitoring service, a telecom carrier/communication NW selection service, a functional restriction service, a PoC (Proof of Concept) service, a personal information management service, an ad-hoc network/DTN (Delay Tolerant Networking) service, etc.

　　Further, the above-described UE categories are merely examples of applications of the technical ideas and exemplary embodiments described in the present document. Needless to say, these technical ideas and embodiments are not limited to the above-described UE and various modifications can be made thereto.

　　Various other modifications will be apparent to those skilled in the art and will not be described in further detail here.

　　For example, the whole or part of the exemplary embodiments disclosed above can be described as, but not limited to, the following supplementary notes.
　　　　(Supplementary note 1)
　　A method performed by a user equipment (UE) the method comprising:
receiving, from an access network node, first information for configuring at least one measurement to be performed by the UE, the first information including second information for configuring measurement reporting, the second information defining at least one parameter for at least one criterion for triggering of at least one measurement reporting event;
performing the at least one measurement based on the first information; and
in a case where the at least one criterion for triggering of at least one measurement reporting event has been met:
transmitting, to the access network node, at least one measurement report for facilitating a mobility decision at the access network node, the at least one measurement report including at least one measurement result for the at least one measurement;
wherein the at least one measurement report is transmitted using a layer 1 or layer 2 control signalling structure.
　　　　(Supplementary note 2)
　　The method according to supplementary note 1, wherein the first information indicates a configuration of at least one resource in which at least one signal for measurement will be transmitted, the at least one signal for measurement including at least one of: at least one periodic signal; at least one semi-persistent signal; and/or at least one aperiodic signal.
　　　　(Supplementary note 3)
　　The method according to supplementary note 2, wherein in a case where the first information indicates a configuration of at least one resource in which at least one periodic signal will be transmitted, event triggered transmission of the at least one measurement report based on measurement of the at least one periodic signal is subject to dynamic activation or triggering by the base station.
　　　　(Supplementary note 4)
　　The method according to supplementary note 2, wherein, in a case where the first information indicates a configuration of at least one resource in which at least one periodic signal will be transmitted, event triggered transmission of the at least one measurement report based on measurement of the at least one periodic signal is not subject to dynamic activation or triggering by the base station.
　　　　(Supplementary note 5)
　　The method according to

supplementary note

2, 3, or 4, wherein, in a case where the first information indicates a configuration of at least one resource in which at least one semi-persistent signal will be transmitted, event triggered transmission of the at least one measurement report based on measurement of the at least one semi-persistent signal is subject to dynamic activation or triggering by the base station.
　　　　(Supplementary note 6)
　　The method according to

supplementary note

2, 3, or 4, wherein, in a case where the first information indicates a configuration of at least one resource in which at least one semi-persistent signal will be transmitted, event triggered transmission of the at least one measurement report based on measurement of the at least one semi-persistent signal is not supported.
　　　　(Supplementary note 7)
　　The method according to any one of supplementary notes 2 to 6, wherein, in a case where the first information indicates a configuration of at least one resource in which at least one aperiodic signal will be transmitted, event triggered transmission of the at least one measurement report based on measurement of the at least one aperiodic signal is subject to dynamic activation or triggering by the base station.
　　　　(Supplementary note 8)
　　The method according to any one of supplementary notes 2 to 6, wherein, in a case where the first information indicates a configuration of at least one resource in which at least one aperiodic signal will be transmitted, event triggered transmission of the at least one measurement report based on measurement of the at least one aperiodic signal is not supported.
　　　　(Supplementary note 9)
　　The method according to supplementary notes 1 to 8, wherein, in the case where the at least one criterion for triggering of at least one measurement reporting event has been met, the method comprises transmitting, to the access network node, an indication that resources are required for an uplink transmission, and receiving an allocation of resources of an uplink channel; and wherein the at least one measurement report is transmitted using those resources.
　　　　(Supplementary note 10)
　　The method according to supplementary note 9, wherein the indication comprises a scheduling request.
　　　　(Supplementary note 11)
　　The method according to supplementary note 9, wherein the indication comprises a dedicated indication for indicating that a measurement report is available.
　　　　(Supplementary note 12)
　　The method according to any one of supplementary notes 9 to 11, wherein the indication comprises a fixed size indication, and the at least one measurement report is transmitted using a fixed size control signal.
　　　　(Supplementary note 13)
　　The method according to supplementary note 12, wherein the indication is a single bit indication.
　　　　(Supplementary note 14)
　　The method according to any one of supplementary notes 9 to 11, wherein the indication indicates an amount of resources required for transmission of, or a size of, a control signal carrying an available measurement report.
　　　　(Supplementary note 15)
　　The method according to supplementary note 14, wherein the indication is a multi-bit indication.
　　　　(Supplementary note 16)
　　The method according to any one of supplementary notes 9 to 15, wherein the indication is transmitted using dedicated resources of a physical uplink control channel allocated by the access network node.
　　　　(Supplementary note 17)
　　The method according to supplementary note 16, wherein the dedicated resources of the physical uplink control channel allocated by the access network node are allocated as resources, of a scheduling request type, that are dedicated to transmission of the indication.
　　　　(Supplementary note 18)
　　The method according to supplementary note 16, wherein the dedicated resources of the physical uplink control channel allocated by the access network node are allocated as resources of a specific type that is specifically dedicated to transmission of an indication for indicating that a measurement report is available.
　　　　(Supplementary note 19)
　　The method according to supplementary note 16, wherein the indication is transmitted using resources of a physical uplink control channel allocated by the access network node for transmission of a scheduling request.
　　　　(Supplementary note 20)
　　The method according to any one of supplementary notes 1 to 19, wherein the at least one measurement report is transmitted using a control signalling structure in the form of a media access control (MAC) control element (CE) carrying the at least one measurement report.
　　　　(Supplementary note 21)
　　The method according to any one of supplementary notes 1 to 20, wherein the at least one measurement report is transmitted, in a physical uplink control channel, or a physical uplink shared channel, using a control signalling structure in the form of uplink control information (UCI).
　　　　(Supplementary note 22)
　　The method according to any one of supplementary notes 1 to 21, wherein the at least one measurement report includes the at least one measurement result in association with at least one of: a physical cell identifier; and/or an identifier of at least one signal to which the result relates.
　　　　(Supplementary note 23)
　　The method according to any one of supplementary notes 1 to 22, wherein the at least one measurement report includes the at least one measurement result in association with at least one of: an indication whether the at least one measurement result is subject to cell level filtering or beam level filtering; a measurement quantity for the at least one measurement result; a number of reported beams in the case that beam level filtering has been applied; an identifier of at least one serving cell and/or candidate cell for which the at least one measurement result applies; and/or an identifier of at least one resource set configured for measurement reporting to which the at least one measurement result relates.
　　　　(Supplementary note 24)
　　The method according to any one of supplementary notes 1 to 23, wherein the at least one measurement result is included in the measurement report subject to the at least one measurement result being no less than a specified threshold.
　　　　(Supplementary note 25)
　　The method according to supplementary note 20 or any supplementary note dependent therefrom, wherein the at least one measurement result includes a plurality of measurement results, a first measurement result of the plurality of measurement results is represented in the at least one measurement report by an indication of an absolute value corresponding to the first measurement result, and at least one other measurement result of the plurality of measurement results is represented in the at least one measurement report by an indication of a differential value, relative to the absolute value, corresponding to the at least one other measurement result.
　　　　(Supplementary note 26)
　　The method according to any one of supplementary notes 1 to 25, wherein the at least one parameter defined by the second information comprises a threshold for triggering at least one measurement reporting event based on a comparison of at least one measurement result for a cell with the threshold.
　　　　(Supplementary note 27)
　　The method according to any one of supplementary notes 1 to 26, wherein the at least one parameter defined by the second information comprises an offset for triggering at least one measurement reporting event based on a comparison, with the offset, of a difference between at least one measurement result for a first cell and at least one measurement result for a second cell.
　　　　(Supplementary note 28)
　　The method according to any one of supplementary notes 1 to 27, wherein the at least one criterion for triggering the at least one measurement reporting event is a criterion that is met without reference to a hysteresis parameter.
　　　　(Supplementary note 29)
　　The method according to any one of supplementary notes 1 to 28, wherein the second information includes third information for configuring a filtering or averaging type.
　　　　(Supplementary note 30)
　　The method according to supplementary note 29, wherein the filtering or averaging type is configured by the third information to be one of: no filtering or averaging; time domain filtering or averaging; cell level filtering or averaging; or both time domain and cell level filtering or averaging.
　　　　(Supplementary note 31)
　　The method according to supplementary note 30, wherein, in a case where the filtering or averaging type is configured to include filtering or averaging of a time domain averaging or filtering type, the second information defines an averaging window size.
　　　　(Supplementary note 32)
　　The method according to any one of supplementary notes 1 to 31, wherein, the second information includes information for configuring the measurement reporting type to be both an event triggered type, and one of a periodic, a semi-persistent, or an aperiodic type.
　　　　(Supplementary note 33)
　　The method according to supplementary note 32, wherein the at least one measurement report includes at least one measurement result of an event triggered type and at least one measurement result of the periodic, semi-persistent, or aperiodic type configured by the information for configuring the measurement reporting type.
　　　　(Supplementary note 34)
　　The method according to supplementary note 32 or 33, wherein, in a case where the information for configuring the measurement reporting type configures the measurement reporting to be both an event triggered type and one of a periodic or semi-persistent type, when the at least one criterion for triggering of at least one measurement reporting event has been met, transmission of the at least one measurement report starts in accordance with the configured periodic or semi-persistent type of measurement reporting.
　　　　(Supplementary note 35)
　　The method according to supplementary note 32, 33, or 34 wherein, in a case where the information for configuring the measurement reporting type configures the measurement reporting to be both an event triggered type and one of a periodic or semi-persistent type, transmission of the at least one measurement report in accordance with the configured periodic or semi-persistent type of measurement reporting occurs when the at least one criterion for triggering of at least one measurement reporting event has been met.
　　　　(Supplementary note 36)
　　The method according to supplementary note 35, wherein the transmission of the at least one measurement report in accordance with the configured periodic or semi-persistent type of measurement reporting occurs in accordance with a periodicity configured by the second information subject to the at least one criterion for triggering of at least one measurement reporting event has been met.
　　　　(Supplementary note 37)
　　The method according to any one of supplementary notes 32 to 36, wherein, in a case where the information for configuring the measurement reporting type configures the measurement reporting to be both an event triggered type and one of a periodic or semi-persistent type, the second information defines at least one threshold for starting and/or stopping measurement reporting of the configured periodic or semi-persistent type, and transmission of the at least one measurement report in accordance with the configured periodic or semi-persistent type of measurement is started or stopped based on the at least one threshold for starting and/or stopping measurement reporting.
　　　　(Supplementary note 38)
　　The method according to supplementary note 37, wherein the at least one threshold for starting and/or stopping measurement reporting comprises at least one threshold for a layer 3 measurement.
　　　　(Supplementary note 39)
　　The method according to supplementary note 37, wherein the at least one threshold for starting and/or stopping measurement reporting comprises at least one threshold for a layer 1 measurement.
　　　　(Supplementary note 40)
　　The method according to any one of supplementary notes 1 to 39, wherein the at least one measurement includes measurements performed in respect of a plurality of beams and wherein the method further comprises selecting beams for which measurement results should be included in the measurement report, up to a maximum number of beams, using a selection procedure.
　　　　(Supplementary note 41)
　　The method according to supplementary note 40, wherein the selection procedure includes ranking the beams based on at least one respective measurement result for each beam and respectively selecting, based on the ranking, at least one beam for each of a plurality of carrier frequencies and/or a plurality of cells until the maximum number of beams has been reached.
　　　　(Supplementary note 42)
　　The method according to supplementary note 40 or 41, wherein each of the plurality of carrier frequencies and/or the plurality of cells have an associated priority, and wherein the order in which the selecting of the at least one beam for each of the plurality of carrier frequencies and/or the plurality of cells occurs is based on the associated priority for each of the plurality of carrier frequencies and/or the plurality of cells.
　　　　(Supplementary note 43)
　　The method according to supplementary note 40, 41 or 42, wherein the selecting of the at least one beam for each of the plurality of carrier frequencies and/or the plurality of cells is subject to a maximum number of beams, and/or a maximum number of cells, per carrier.
　　　　(Supplementary note 44)
　　The method according to any one of supplementary notes 40 to 43, wherein the selecting of the at least one beam for each of the plurality of carrier frequencies and/or the plurality of cells is subject to a maximum number of beams per cell.
　　　　(Supplementary note 45)
　　The method according to supplementary notes 1 to 44, further comprising receiving, from the access network node, a cell switch command for the mobility procedure, the cell switch command including a transmission configuration indication (TCI) that is common to a plurality of channels and/or signals, and receiving a respective channel specific or signal specific TCI for each of a plurality of channels and/or signals.
　　　　(Supplementary note 46)
　　The method according to supplementary note 45, wherein the respective channel specific or signal specific TCI for each of a plurality of channels and/or signals is received separately following the cell switch command.
　　　　(Supplementary note 47)
　　The method according to supplementary note 45, wherein the respective channel specific or signal specific TCI for each of a plurality of channels and/or signals is included in the cell switch command.
　　　　(Supplementary note 48)
　　The method according to any one of supplementary notes 1 to 47, wherein the mobility procedure is a mobility procedure that is triggered at a layer below layer 3.
　　　　(Supplementary note 49)
　　A user equipment (UE) comprising:
means for receiving, from an access network node, first information for configuring at least one measurement to be performed by the UE, the first information including second information for configuring measurement reporting, the second information defining at least one parameter for at least one criterion for triggering of at least one measurement reporting event;
means for performing the at least one measurement based on the first information; and
means for, in a case where the at least one criterion for triggering of at least one measurement reporting event has been met, transmitting, to the access network node, at least one measurement report for facilitating a mobility decision at the access network node, the at least one measurement report including at least one measurement result for the at least one measurement;
wherein the at least one measurement report is transmitted using a layer 1 or layer 2 control signalling structure.
　　　　(Supplementary note 50)
　　A method performed by an access network node the method comprising:
transmitting, to a user equipment (UE), first information for configuring at least one measurement to be performed by the UE, the first information including second information for configuring measurement reporting, the second information defining at least one parameter for at least one criterion for triggering of at least one measurement reporting event;
receiving, in a case where the at least one criterion for triggering of at least one measurement reporting event has been met, from the UE, at least one measurement report for facilitating a mobility decision at the access network node, the at least one measurement report including at least one measurement result for at least one measurement performed by the UE; and
making a mobility decision based on the at least one measurement report;
wherein the at least one measurement report is transmitted using a layer 1 or layer 2 control signalling structure.
　　　　(Supplementary note 51)
　　An access network node comprising:
means for transmitting, to a user equipment (UE), first information for configuring at least one measurement to be performed by the UE, the first information including second information for configuring measurement reporting, the second information defining at least one parameter for at least one criterion for triggering of at least one measurement reporting event;
means for receiving, in a case where the at least one criterion for triggering of at least one measurement reporting event has been met, from the UE, at least one measurement report for facilitating a mobility decision at the access network node, the at least one measurement report including at least one measurement result for at least one measurement performed by the UE; and
means for making a mobility decision based on the at least one measurement report;
wherein the at least one measurement report is transmitted using a layer 1 or layer 2 control signalling structure.

　　This application is based upon and claims the benefit of priority from Great Britain Patent Application No. 2300921.0, filed on January 20, 2023, the disclosure of which is incorporated herein in its entirety by reference.

1 COMMUNICATION SYSTEM
3 USER EQUIPMENT
5 BASE STATION
7 CORE NETWORK
9 CELL
10 CONTROL PLANE FUNCTIONS
11 USER PLANE FUNCTIONS
31 TRANSCEIVER CIRCUIT
33 ANTENNA
35 USER INTERFACE
37 CONTROLLER
39 MEMORY
41 OPERATING SYSTEM
43 COMMUNICATIONS CONTROL MODULE
45 MEASUREMENT MANAGEMENT MODULE
47 MEASUREMENT REPORTING MODULE
51 TRANSCEIVER CIRCUIT
53 ANTENNA
55 CORE NETWORK INTERFACE
57 CONTROLLER
59 MEMORY
61 OPERATING SYSTEM
63 COMMUNICATIONS CONTROL MODULE
65 MEASUREMENT CONFIGURATION MANAGEMENT MODULE
67 MEASUREMENT REPORT MANAGEMENT MODULE

Claims

　　A method performed by a user equipment (UE), the method comprising:
　　receiving, from an access network node, first information for configuration for measurement reporting, and second information for defining at least one parameter for at least one event for triggering a layer 1 measurement reporting;
　　performing a layer 1 measurement; and
　　in a case where one or more of the at least one event for triggering the layer 1 measurement reporting has occurred, initiating a procedure for the layer 1 measurement reporting,
　　wherein the procedure for the layer 1 measurement reporting includes transmitting a layer 1 measurement report using a layer 1 or layer 2 control signalling structure.
　　The method according to claim 1, wherein
　　the first information indicates resources for transmitting the layer 1 measurement report, and
　　the layer 1 measurement report is transmitted using the resources indicated by the first information.
　　The method according to claim 1 or 2, further comprising:
　　receiving information for activating the layer 1 measurement reporting, and wherein
　　the initiating the procedure for the layer 1 measurement reporting is performed after the activating the layer 1 measurement reporting.
　　The method according to claim 1, wherein
　　the first information indicates resources for transmitting an indication for the layer 1 measurement reporting,
　　the initiating the procedure for the layer 1 measurement reporting is performed by transmitting the indication using the resources indicated by the first information, and
　　the method further comprises receiving third information for resources for transmitting the the layer 1 measurement report, and
　　wherein the procedure for the layer 1 measurement reporting includes transmitting the layer 1 measurement report using the resources indicated by the third information.
　　The method according to claim 4, wherein　　the resources are allocated for a physical uplink control channel, PUCCH, for a scheduling request.
　　The method according to claim 4 or 5, wherein
　　the resources are allocated for a periodic PUCCH dedicated to transmitting the indication.
　　The method according to any one of claims 4 to 6, wherein
　　the indication has 1-bit information, and
　　the indication indicates that a size of the layer 1 measurement report is a fixed size.
　　The method according to any one of claims 4 to 6, wherein
　　the indication has multiple bits information, and
　　the indication indicates a size of the layer 1 measurement report, by the multiple bits information.
　　The method according to any one of claims 1 to 8, wherein
　　the layer 1 measurement report is transmitted using a control signalling structure in the form of a media access control (MAC) control element (CE) carrying the layer 1 measurement report.
　　The method according to any one of claims 1 to 8, wherein
　　the layer 1 measurement report is transmitted, in a physical uplink control channel, or a physical uplink shared channel, using a control signalling structure in the form of uplink control information (UCI).
　　The method according to any one of claims 1 to 10, wherein
　　the layer 1 measurement report includes at least one measurement result in association with at least one of:
　　　　a physical cell identifier;
　　　　an identifier of at least one signal to which the at least one measurement result relates;
　　　　an indication whether the at least one measurement result is subject to cell level filtering or beam level filtering;
　　　　a measurement quantity for the at least one measurement result;
　　　　a number of reported beams in the case that beam level filtering has been applied;
　　　　an identifier of at least one serving cell and/or candidate cell for which the at least one measurement result applies; and/or
　　　　an indication of at least one resource configured for the layer 1 measurement reporting to which the at least one measurement result relates.
　　The method according to claim 11, wherein
　　the at least one measurement result includes a plurality of measurement results,
　　a first measurement result of the plurality of measurement results is represented in the layer 1 measurement report by an indication of an absolute value corresponding to the first measurement result, and
　　at least one other measurement result of the plurality of measurement results is represented in the layer 1 measurement report by an indication of a differential value, relative to the absolute value, corresponding to the at least one other measurement result.
　　The method according to claim 12, wherein
　　the absolute value is represented by 7 bit information, and
　　the differential value is represented by 4 bit information.
　　The method according to any one of claims 1 to 13, wherein
　　the layer 1 measurement report includes at least one measurement result,
　　the at least one measurement results includes results of measurements performed in respect of a plurality of beams, and
　　the method further comprises selecting beams for which measurement results should be included in the layer 1 measurement report, up to a maximum number of beams.
　　The method according to claim 14, wherein
　　the selecting is performed by:
　　　　ranking the beams based on at least one respective measurement result for each beam; and
　　　　respectively selecting, based on the ranking, at least one beam for each of a plurality of carrier frequencies and/or a plurality of cells until the maximum number of beams has been reached.
　　The method according to claim 14 or 15, wherein
　　each of the plurality of carrier frequencies and/or the plurality of cells have an associated priority, and
　　the order in which the selecting of the at least one beam for each of the plurality of carrier frequencies and/or the plurality of cells occurs is based on the associated priority for each of the plurality of carrier frequencies and/or the plurality of cells.
　　The method according to any one of claims 14 to 16, wherein
　　the selecting of the at least one beam for each of the plurality of carrier frequencies and/or the plurality of cells is subject to the maximum number of beams and/or a maximum number of cells per carrier.
　　The method according to any one of claims 14 to 17, wherein
　　the selecting of the at least one beam for each of the plurality of carrier frequencies and/or the plurality of cells is subject to a maximum number of beams per cell.
　　The method according to any one of claims 14 to 18, wherein
　　the maximum number of beams is represented by a product of a number of beams per cell and a number of cells.
　　The method according to any one of claims 1 to 19, wherein
　　the at least one parameter includes a threshold or an offset for determining that one of the at least one event for triggering the layer 1 measurement reporting has occurred.
　　The method according to any one of claims 1 to 20, wherein
　　the second information includes fourth information for configuring a filtering or averaging type, and
　　the filtering or averaging type is configured to be one of:
　　　　no filtering or averaging;
　　　　time domain filtering or averaging;
　　　　cell level filtering or averaging; or
　　　　both time domain and cell level filtering or averaging.
　　The method according to claim 21, wherein,
　　in a case where the filtering or averaging type is configured to include filtering or averaging of a time domain averaging or filtering type, the second information defines an averaging window size.
　　The method according to any one of claims 1 to 22, wherein,
　　the second information includes fifth information for configuring a type of the layer 1 measurement reporting to be both an event triggered type, and one of a periodic, a semi-persistent, or an aperiodic type.
　　The method according to claim 23, wherein
　　the layer 1 measurement report includes at least one measurement result of the event triggered type and at least one measurement result of the periodic, semi-persistent, or aperiodic type configured by the fifth information.
　　The method according to claim 23 or 24, wherein
　　in a case where the fifth information configures the layer 1 measurement reporting to be both the event triggered type and one of the periodic or semi-persistent type, and the at least one event for triggering the layer 1 measurement reporting has occurred, transmission of the layer 1 measurement report starts in accordance with configuration for the periodic or semi-persistent type of the layer 1 measurement reporting.
　　The method according to any one of claims 23 to 25, wherein
　　in a case where the fifth information configures the layer 1 measurement reporting to be both the event triggered type and one of the periodic or semi-persistent type, transmission of the layer 1 measurement report in accordance with configuration for the periodic or semi-persistent type of the layer 1 measurement reporting occurs when the at least one event for triggering the layer 1 measurement reporting has occured.
　　The method according to claim 26, wherein
　　the transmission of the layer 1 measurement report in accordance with the configuration for the periodic or semi-persistent type of the layer 1 measurement reporting occurs in accordance with a periodicity configured by the second information subject to the at least one event for triggering the layer 1 measurement reporting has occurred.
　　The method according to any one of claims 23 to 27, wherein
　　in a case where the fifth information configures the layer 1 measurement reporting to be both the event triggered type and one of the periodic or semi-persistent type, the second information defines at least one threshold for starting and/or stopping the layer 1 measurement reporting of the periodic or semi-persistent type, and transmission of the layer 1 measurement report in accordance with the periodic or semi-persistent type of the layer 1 measurement is started or stopped based on the at least one threshold for starting and/or stopping measurement reporting.
　　The method according to claim 28, wherein
　　the at least one threshold for starting and/or stopping measurement reporting comprises at least one threshold for a layer 3 measurement.
　　The method according to claim 28, wherein
　　the at least one threshold for starting and/or stopping measurement reporting comprises at least one threshold for a layer 1 measurement.
　　The method according to any one of claims 1 to 30, further comprising:
　　receiving, from the access network node, a cell switch command for a mobility procedure, the cell switch command including a transmission configuration indication (TCI) that is common to a plurality of channels and/or signals; and
　　receiving a respective channel specific or signal specific TCI for each of a plurality of channels and/or signals.
　　The method according to claim 31, wherein
　　the respective channel specific or signal specific TCI for each of a plurality of channels and/or signals is received separately following the cell switch command.
The method according to claim 31, wherein
　　the respective channel specific or signal specific TCI for each of a plurality of channels and/or signals is included in the cell switch command.
　　The method according to claim 31, wherein
　　the mobility procedure is a mobility procedure that is triggered at a layer below layer 3.
　　A user equipment (UE) comprising:
　　means for receiving, from an access network node, first information for configuration for measurement reporting, and second information for defining at least one parameter for at least one event for triggering layer 1 measurement reporting;
　　means for performing a layer 1 measurement; and
　　means for, in a case where one or more of the at least one event for triggering the layer 1 measurement reporting has occurred, initiating a procedure for the layer 1 measurement reporting,
　　wherein the procedure for the layer 1 measurement reporting includes transmitting a layer 1 measurement report using a layer 1 or layer 2 control signalling structure.
　　A method performed by an access network node the method comprising:
　　transmitting, to a user equipment (UE), first information for configuration for measurement reporting, and second information for defining at least one parameter for at least one event for triggering a layer 1 measurement reporting;
　　in a case where one or more of the at least one event for triggering the layer 1 measurement reporting has occurred, initiating a procedure, with the UE, for the layer 1 measurement reporting,
　　wherein the procedure for the layer 1 measurement reporting includes receiving a layer 1 measurement report using a layer 1 or layer 2 control signalling structure.
　　An access network node comprising:
　　means for transmitting, to a user equipment (UE), first information for configuration for measurement reporting, and second information for defining at least one parameter for at least one event for triggering the layer 1 measurement reporting;
　　means for receiving, in a case where one or more of the at least one event for triggering the layer 1 measurement reporting has occurred, initiating a procedure, with the UE, for the layer 1 measurement reporting,
　　wherein the procedure for the layer 1 measurement reporting includes receiving a layer 1 measurement report using a layer 1 or layer 2 control signalling structure.