Method performed by mobile terminal, method performed by access network node, mobile terminal, and access network node

Abstract

A method performed by a mobile terminal is disclosed. The method includes receiving, from an access network node, information indicating at least one configuration of adaptation for a channel used during cell discontinuous reception (DRX) / discontinuous transmission (DTX) inactive duration regarding the access network node; and receiving, from the access network node, downlink control information indicating which of the at least one configuration should be used.

Description

METHOD PERFORMED BY MOBILE TERMINAL, METHOD PERFORMED BY ACCESS NETWORK NODE, MOBILE TERMINAL, AND ACCESS NETWORK NODE

[0001] The present disclosure relates to a communication system and to parts thereof. 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 Long Term Evolution (LTE)-Advanced, Next Generation or 5G networks, future generations, and beyond). The disclosure has particular, although not necessarily exclusive, relevance to the adaptation of common channels and / or common signals for user equipment operating in idle mode, inactive mode and / or connected mode in the context of network energy saving (NES) enhancements such as cell discontinuous reception (DRX) and cell discontinuous transmission (DTX).

[0002] Earlier developments of the 3GPP standards were referred to as the Long-Term Evolution (LTE) of Evolved Packet Core (EPC) network and Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN), also commonly referred as '4G'. More recently, the term '5G' and 'new radio' (NR) has started to be used to refer to an evolving communication technology that is expected to support a variety of applications and services. Various details of 5G networks are described in, for example, the 'NGMN 5G White Paper' V1.0 (NPL 1) by the Next Generation Mobile Networks (NGMN) Alliance, which document is available from https: / / www.ngmn.org / 5g-white-paper.html. 3GPP intends to support 5G by way of the so-called 3GPP Next Generation (NextGen) radio access network (RAN) and the 3GPP NextGen core network.

[0003] Under the 3GPP standards, a NodeB (or an eNB in LTE, and gNB in 5G) is the radio access network (RAN) node (or simply 'access node', 'access network node' or 'base station') via which communication devices (user equipments or 'UEs') connect to a core network and communicate with other communication devices or remote servers. For simplicity, the present application will use the term access network node, RAN node or base station to refer to any such access nodes.

[0004] 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 RAN nodes. 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 communication network for sending / receiving data, regardless of whether such communication devices are controlled by human input or software instructions stored in memory.

[0005] In the current 5G architecture, the gNB structure may be split into two or more parts. In some RAN implementations there are two parts, known as the Central Unit (CU or gNB-CU) - sometimes referred to as a 'control unit' - and the Distributed Unit (DU or gNB-DU), connected by an F1 interface. This enables the use of a 'split' architecture in which the typically 'higher' CU layers (for example, but not necessarily or exclusively, Packet Data Convergence Protocol (PDCP) and Radio Resource Control (RRC) layers) and the, 'lower' DU layers (for example, but not necessarily or exclusively, Radio Link Control (RLC), Media (sometimes referred to as 'Medium') Access Control (MAC), and Physical (PHY) layers) are separated between a particular CU, and one or more DUs that are connected to and controlled by that CU via the F1 interface. Thus, for example, the higher layer CU functionality for a number of gNBs 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 separately for each gNB.

[0006] In more recently proposed RAN distributed architectures, in addition to the CU and DU, the concept of a Radio Unit (RU) - sometimes referred to as a 'remote unit' - has been introduced. In this architecture the RU is responsible for handling the digital front end (DFE), digital beamforming functionality and, typically, the functionality of the lower parts of the PHY layer, whilst the DU typically handles the higher parts of the PHY layer and the RLC and MAC layers. The CU in this architecture continues to be responsible for controlling one or more DUs (each DU corresponding to a different respective gNB) and to handle higher layer signalling (typically RRC and PDCP layers).

[0007] The actual functional split between the CU and DUs (and potentially RUs where applicable) of these distributed architectures is flexible allowing the functionality to be optimised for different use cases. Effectively, the split architecture enables a 5G network to use a different distribution of protocol stacks between CU and DUs (and potentially RUs) depending on, for example, midhaul availability and network design.

[0008] The choice of how to split functions in the architecture depends on, among other things, factors related to radio network deployment scenarios, constraints and intended supported use cases. Key considerations include: the need to support a specific quality of service for each service offered and for real / non-real time applications; support of specific user density and load demand in a given geographical area; and available transport networks with different performance levels.

[0009] As cellular communication systems evolve, there is an increasing need for wireless communication networks having improved energy efficiency. A reduction in the amount of energy needed to operate a communication network beneficially reduces the environmental impact of operating the system, and also reduces the operational costs. Moreover, for battery-powered devices (for example, a UE) reduced power consumption extends the battery life of the device. However, more recent developments of cellular communication systems (for example to implement wide channel bandwidths, to enable operations at significantly higher frequencies than previously, to provide improved capacity, and the like) tend to increase, rather than reduce, power demand and thus present significant challenges when it comes to energy saving.

[0010] In this context, a number of network energy saving (NES) techniques are typically implemented in cellular communication systems, and improvements to those NES techniques and completely new techniques are being developed. The NES techniques being considered include time, frequency, spatial, and power domain adaptation techniques.

[0011] One method of achieving energy savings in a cellular communication system is to reduce the energy requirements associated with communication between a UE and an associated RAN node. The energy consumption arising from such communication includes a dynamic part that is associated with data transmission and reception, and a static part that is associated with operations of the UE, and the RAN node, that are performed even when there is no ongoing data transmission or reception. The static part may include, for example, the power required to operate a UE in a mode in which the UE is able to receive and decode a physical downlink control channel (PDCCH) transmitted by a RAN node.

[0012] Energy saving modes may be configured for one or more devices in the system (e.g., a UE). For example, a UE may be configured to operate in an energy saving mode (which may also be referred to as a sleep mode) in which the UE performs a reduced number of transmissions, or in which the UE is configured not to attempt to transmit and / or to receive signals during a particular time period. Such operation is commonly referred to as DRX / DTX which stands for Discontinuous Reception (DRX) and Discontinuous Transmission (DTX). DRX for a UE includes idle mode DRX and connected mode DRX (C-DRX). In idle mode DRX, the UE periodically wakes up to monitor for paging messages and goes back to a sleep mode if paging message is not intended for it. In C-DRX, the UE powers down most of its circuitry when there are no packets to be received or transmitted. During this time the UE nevertheless still monitors for a physical downlink control channel (PDCCH) occasionally during a DRX 'active' state, or DRX 'ON' period. The time during which UE does not monitor the PDCCH is often called a DRX 'sleep' or 'inactive' state, or DRX 'OFF' period.

[0013] More recently, similar discontinuous operation of the cell or cells provided by a RAN node has been developed. This is often referred to as 'cell DTX / DRX'. With cell DTX / DRX, the RAN node operating a cell stops transmitting and receiving in that cell during certain periods of time. The UEs that are served by the cell may be provided with information that allows them to determine when the RAN node is in an active or 'ON' state (and is therefore able to communicate with the UE) and when it is in an inactive or 'OFF' state (and is therefore not able to communicate with the UE).

[0014] Previous NES development has focused, primarily, on NES enhancements aimed at reducing energy associated with connected mode UEs during a low cell load scenario. These enhancements deliberately avoided any impact on idle or legacy UE operation and focused on reducing energy associated with user specific signals and channels. However, this focus has limited the NES gains that are potentially achievable.

[0015] For example, NES gains from cell DTX and DRX operation are limited by the fact that the RAN node still needs to be ready for the periodic transmission of synchronization signal / physical broadcast channel (PBCH) blocks (SSBs) that an idle / inactive UE is required to receive to be able to synchronise with the network and obtain information for accessing a cell of the that RAN node. This is because an 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 a corresponding cell (e.g., parameters required for acquiring system information block 1 (SIB1) which carries other minimum system information). Similarly, the NES gains are limited by the need to receive paging transmissions and / or to communicate on a random-access channel (RACH). Moreover, proposed power and spatial domain adaptations are limited to the physical downlink shared channel (PDSCH).

[0016] Hence, SSB transmissions, and Idle mode operations in general, are not impacted by cell DTX / DRX. This means that SSB, RACH, Paging and SIBs continue to be transmitted even during a non-active (or 'inactive') period of the DTX and / or DRX.

[0017] More recently, support for obtaining an SSB, on demand, for a secondary cell (SCell) has been developed for connected mode UEs. Similarly, support for obtaining, on demand, SIB1 for idle UEs has been developed. However, if SSB transmissions are not reduced due to operations for UEs in idle or inactive mode, the potential benefits offered by supporting on demand SSB could be severely limited, or lost, because the RAN node still needs to be ready for periodic SSB transmission.

[0018] Currently, a RAN node can implement a reduced downlink transmission / uplink reception activity without an explicit a cell DTX / DRX pattern albeit with restrictions due to UE DRX configurations and any configured transmission / reception (e.g., for common channels / signals). Currently C-DRX is configured on a per UE basis. Coordination to align the DRX cycles or offsets for different UEs is potentially achievable via RRC signalling. During a UE DRX off period, the UE does not expect to monitor for downlink communication via the PDCCH. Nevertheless, the UE is allowed to initiate uplink transmission according to (pre)configured resources (e.g. using a physical uplink control channel (PUCCH), a RACH, a scheduling request (SR), or a configured grant (CG) physical uplink shared channel (PUSCH)). Thus, alignment of DRX patterns (or the omission of one or more DRX pattern) across multiple UE's is achievable based on an appropriate RAN node implementation.

[0019] One possible technique for NES, therefore, may involve providing one or more mechanisms for informing a UE of whether a cell will remain inactive. This may, for example, include enhancements to a UE DRX configuration, e.g. to align / omit DRX cycles or start offsets of DRX, for UEs in a connected mode or an idle / inactive mode. This has the potential to allow for longer opportunities for cell inactivity. Thus, during a cell DTX / DRX, the cell may be able to avoid any transmission / reception or only engage in limited transmission / reception. For example, the cell may not need to transmit or receive some periodic signals / channels, or include some common channels / signals as well as UE specific channels / signals.

[0020] It can be seen, therefore, that there are a number of matters that may need to be considered when developing further NES based.

[0021] In summary, for example, for Cell DTX / DRX (especially in the context of UEs operating in a connected mode), the following may need to be considered: 　　How support might be provided for turning off tracking reference signals (TRS) for at least some TRS occasions that occur during a non-active time of a cell DTX / DRX cycle for UEs in connected modes, subject to minimum UE synchronization impact; 　　How support might be provided for UE triggered Cell DTX / DRX adaptation based on an indication provided by a UE; 　　How to provide for efficient handling of traffic bursts without Cell DTX / DRX de-activation; 　　How support might be provided for multiple DTX / DRX patterns on the same serving cell; and 　　How support might be provided for inter-node information exchange relating to cell DTX / DRX.

[0022] For example, it may be appropriate to implement the UE triggering of cell DTX / DRX adaptation and the support for multiple cell DTX / DRX configurations mentioned above as part of the provision of a more reliable and flexible cell DTX / DRX adaptation capability.

[0023] It will be appreciated that these need to be considered in a context in which there may be no provision for dynamic switching among multiple cell DTX / DRX configurations.

[0024] Similarly, in the context of common signal / channel transmissions, the following may need to be considered: 　　Possible adaptation of SSB in time domain, e.g. by appropriate adaptation of SSB transmission periodicity; 　　Possible adaptation of SSB in the spatial domain, e.g. by allowing adaptation of SSB beam transmission pattern, and if considered to be beneficial how such adaptation may be implemented efficiently; 　　Possible adaptation of the physical RACH (PRACH) procedures in the time domain; 　　Possible adaptation of PRACH in spatial domain, e.g. by means of non-uniform PRACH resources per SSB if considered to be beneficial how such adaptation may be implemented efficiently; and 　　Possible adaptation of paging occasions including confining paging occasions in the time domain (ideally whilst ensuring that there is no (or insignificant) associated paging latency increases).

[0025] It will be appreciated that these need to be considered in a context in which there is no (or insignificant) negative impact on legacy UEs (i.e., UEs that are not configured to take any new NES enhancements into account when operating), unless a commensurately significant benefit will arise from implementing the enhancement that outweighs any negative impacts on legacy UEs.

[0026] Moreover, further enhancements for cell DTX / DRX in the context of UEs operating in an idle / inactive mode may need to be considered.

[0027] NES enhancements that might need to be considered also include, for example: enhancements to radio link monitoring, cell (re)selection, handover, initial access, etc; and / or enhancements to SSB / SIB1 transmission adaptation including in respect of transmission periodicity and / or occasions based on a RAN node indication and / or a UE request.

[0028] It can be seen, therefore, that there is room for significant further development in a number of areas to achieve or improve on many of the benefits that the use of NES techniques has to offer.

[0029] As foreshadowed above, one area for development is the adaptation of common control channels / signals for a UE in an idle / inactive mode and in a connected mode. These may include, for example, transmissions on downlink channels such as: 　　SSB transmissions; 　　Transmissions on the PDCCH within a common search space, e.g., for system information (SI), paging, and RACH procedure signalling; and 　　Transmissions Reference signals (RS) for measurement for the purposes of radio link management / monitoring (RLM) / radio resource management / monitoring (RRM) and / or mobility management.

[0030] This disclosure therefore describes a number of possible enhancements related to the adaptation of common signal / channel transmissions based, for example, on extensions to cell DTX / DRX techniques, for UEs in idle / inactive mode and / or connected mode.

[0031] NPL 1: NGMN 5G White Paper' V1.0 NPL 2: 3GPP TS 38.473

[0032] One or more apparatus and / or one or more associated methods are disclosed that aim to at least partially contribute to meeting one or more of above needs.

[0033] In one aspect there is provided a method performed by a mobile terminal, the method comprising: 　　receiving, from an access network node, information indicating at least one configuration of adaptation for a channel used during cell discontinuous reception (DRX) / discontinuous transmission (DTX) inactive duration regarding the access network node; and 　　receiving, from the access network node, downlink control information indicating which of the at least one configuration should be used.

[0034] In one aspect there is provided a method performed by an access network node, the method comprising: 　　transmitting, to a mobile terminal, information indicating at least one configuration of adaptation for a channel used during cell discontinuous reception (DRX) / discontinuous transmission (DTX) inactive duration regarding the access network node; and 　　transmitting, to the mobile terminal, downlink control information indicating which of the at least one configuration should be used.

[0035] In one aspect there is provided a mobile terminal comprising: 　　means for receiving, from an access network node, information indicating at least one configuration of adaptation for a channel used during cell discontinuous reception (DRX) / discontinuous transmission (DTX) inactive duration regarding the access network node; and 　　means for receiving, from the access network node, downlink control information indicating which of the at least one configuration should be used.

[0036] In one aspect there is provided an access network node comprising: 　　means for transmitting, to a mobile terminal, information indicating at least one configuration of adaptation for a channel used during cell discontinuous reception (DRX) / discontinuous transmission (DTX) inactive duration regarding the access network node; and 　　means for transmitting, to the mobile terminal, downlink control information indicating which of the at least one configuration should be used.

[0037] In the present disclosure, one or more apparatus and / or one or more associated methods are disclosed that aim to at least partially contribute to implementing one or more of the above mentioned possible enhancements.

[0038] The various functional means described below that are part of the UE may be provided by a memory and one or more processors that execute instructions stored in the memory. Similarly, the various functional means described below that are part of the access network node may be provided by a memory and one or more processors that execute instructions stored in the memory.

[0039] Various examples described below may be implemented by means of a computer program product comprising computer implementable instructions for causing a programmable computer to carry out the any of the methods described below. The computer implementable instructions may be provided as a signal or on a tangible computer readable medium.

[0040] According to the present disclosure, it is possible to provide a method performed by an access network node, a method performed by a user equipment, a method performed by a core network node, an access network node, a user equipment, and a core network node.

[0041] Examples of the disclosure will now be described, by way of example, with reference to the accompanying drawings in which:

[0042] Fig. 1 schematically illustrates a mobile ('cellular' or 'wireless') communication system;Fig. 2 illustrates a typical frame structure that may be used in the communication system of Fig. 1;Fig. 3 illustrates a typical resource grid that may be used in the communication system of Fig.1;Fig. 4 illustrates an example of a DRX / DTX cycle or pattern that may be used in the communication system of Fig. 1;Fig. 5 is a simplified sequence diagram illustrating configuration / indication of channel / signal adaptation that may be employed in the communication system of Fig. 1;Fig. 6 is a simplified sequence diagram illustrating a procedure involving the transmission of a paging early indication, in the event that a UE is to be paged, that may be employed in the communication system of Fig. 1;Fig. 7 is a simplified sequence diagram illustrating a procedure involving the transmission of a paging early indication, in the event that a UE is not going to be paged, that may be employed in the communication system of Fig. 1;Fig. 8 is a simplified illustration of the transmission of the paging early indication, shown in Fig. 6, during a cell DTX active period;Fig. 9 is another simplified illustration of the transmission of the paging early indication, shown in Fig. 6, during a cell DTX inactive period;Fig. 10 is a simplified sequence diagram illustrating another procedure involving the transmission of a paging early indication, in the event that a UE is to be paged, that may be employed in the communication system of Fig. 1;Fig. 11 is a simplified sequence diagram illustrating a procedure in which a paging early indication occasion and a paging occasion are both skipped, in the event that a UE is not going to be paged, that may be employed in the communication system of Fig. 1;Fig. 12 is a simplified illustration of the skipping of the paging occasion, shown in Fig. 11, during a cell DTX inactive period;Fig. 13 is a simplified sequence diagram illustrating a number of possible ways to notify a UE of activation / deactivation of a cell DTX / DRX configuration that may be employed in the communication system of Fig. 1;Fig. 14 is a simplified sequence diagram illustrating a number of possible techniques for supporting cell DTX / DRX adaptation without deactivation that may be employed in the communication system of Fig. 1;Fig. 15 is a simplified illustration of the operation of RACH occasions, in the context of cell DTX / DRX (specifically cell DRX), that may be used in the communication system of Fig. 1;Fig. 16 is a simplified sequence diagram illustrating a method for supporting adaptation of a configuration for common channel / signal communication during a cell DTX / DRX inactive duration for a connected mode UE that may be employed in the communication system of Fig. 1;Fig. 17 is a simplified sequence diagram illustrating a method for supporting adaptation of a configuration for common channel / signal communication during a cell DTX / DRX inactive duration for an idle / inactive mode UE that may be employed in the communication system of Fig. 1;Fig. 18 is a schematic block diagram illustrating the main components of a UE for the communication system of Fig. 1; andFig. 19 is a schematic block diagram illustrating the main components of a RAN node for the communication system of Fig. 1.

[0043] < Overview > 　　An exemplary communication system will now be described in general terms, by way of example only, with reference to Figs. 1 to 6.

[0044] Fig. 1 schematically illustrates a mobile ('cellular' or 'wireless') communication system 1 to which the examples described herein are applicable.

[0045] In the communication system 1, one or more user equipments (UEs) 3-1, 3-2, 3-3 (e.g., mobile telephones and / or other mobile or stationary devices) can communicate with each other via a (radio) access network ((R)AN) node 5 that operates according to one or more compatible radio access technologies (RATs). In the illustrated example, the RAN node 5 comprises a base station 5 or 'gNB' 5 operating one or more associated cells 9. Communication via the RAN node 5 is typically routed through a core network 7 (e.g., a 5G / 6G and / or later generations core network or evolved packet core network (EPC)).

[0046] As those skilled in the art will appreciate, whilst three UEs 3 and one RAN node 5 are shown in Fig. 1 for illustration purposes, the system, when implemented, will typically include one or more other RAN nodes 5 and UEs 3.

[0047] Each RAN node 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 RAN nodes 5 may be configured to support 4G, 5G, 6G and / or later generations, and / or any other 3GPP or non-3GPP communication protocols.

[0048] The UEs 3 and their serving RAN node 5 are connected via an appropriate air interface (for example the so-called 'Uu' interface and / or the like). Neighbouring RAN nodes 5 may be connected to each other via an appropriate RAN node to RAN node interface (such as the so-called 'X2' interface, 'Xn' interface and / or the like).

[0049] The core network 7 includes a number of logical nodes (or 'functions') for supporting communication in the communication system 1. In this example, the core network 7 comprises control plane functions (CPFs) 10 and one or more network node entities for the communication of user data (e.g. user plane functions (UPFs) 11). The CPFs 10 include one or more network node entities for the communication of control signalling (e.g. Access and Mobility Management Functions (AMFs) 10-1) (or one or more function nodes with equivalent functionality under a different name), one or more network node entities for session management (e.g. Session Management Functions (SMFs) 10-2) (or one or more function nodes with equivalent functionality under a different name) and a number of other functions 10-n (such as, for example an Authentication Server Function (AUSF) which facilitates security processes).

[0050] The RAN node 5 is connected to the core network nodes via appropriate interfaces (or 'reference points') such as an N2 reference point between the RAN node 5 and the AMF 10-1 for the communication of control signalling, and an N3 reference point between the RAN node 5 and each UPF 11 for the communication of user data. The UEs 3 are each connected to the AMF 10-1 via a non-access stratum (NAS) connection over an appropriate interface (e.g. an N1 reference point (analogous to the S1 reference point in LTE)). It will be appreciated that N1 communications are routed transparently via the RAN node 5.

[0051] Each UPF 11 is connected to an external data network 20 (e.g., an IP network such as the internet) via an appropriate interface (e.g. an N6 reference point) for communication of the user data.

[0052] The AMF 10-1 performs mobility management related functions, maintains the NAS connection with each UE 3 and manages UE registration. The AMF 10-1 is also responsible for managing paging. The AMF 10-1 receives user information sent through the network and forwards the information to the SMF 10-2. The AMF 10-1 is also responsible for managing paging.

[0053] 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 uses user information provided via the AMF 10-1 to determine what session manager would be best assigned to the user. The SMF 10-2 may be considered effectively to be a gateway from the user plane to the control plane of the network. The SMF 10-2 also allocates IP addresses to each UE 3.

[0054] The RAN node 5 of the communication system 1 is configured to operate at least one cell 9 on an associated time-division duplex (TDD) carrier that operates in unpaired spectrum and / or at least one cell 9 on an associated frequency-division duplex (FDD) carrier that operates in paired spectrum.

[0055] The RAN node 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. The DL physical channels correspond to resource elements (REs) carrying information originated from a higher layer.

[0056] The DL 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 data transmissions on a 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.

[0057] The RAN node 5 also transmits DL physical signals that do not carry any data, such as, 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 RAN node 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).

[0058] Similarly, the UEs 3 are configured for transmission of, and the RAN node 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, the 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 an UL control / data signal, and / or sounding reference signals (SRS) used for UL channel measurement.

[0059] The RAN node 5 is also configured to transmit synchronization signal / physical broadcast channel (PBCH) blocks (SSBs) periodically in the cell or 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 the PBCH carrying a 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).

[0060] Each UE 3 is configured to search for SSBs when scanning for a cell 9 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.

[0061] In addition to a connected mode / state in which the UE 3 has an active connection to the wider communication network (e.g., for the purposes of communicating with other UEs 3 and / or receiving a data based service), the UE 3 is capable of operating in other modes / states including an idle mode / state and an inactive mode / state.

[0062] In the idle mode / state, the UE 3 typically performs mechanisms such as reading system information and system information updates, cell selection and reselection, and paging monitoring. The UE 3 also performs neighbour cell measurements and is in control of mobility and when to reselect to a better cell 9.

[0063] The inactive mode / state is similar to the idle mode. However, in this mode / state a UE context for the UE 3 is saved in the network so that any delay in state transition from the inactive mode / state to a connected mode / state is reduced. The UE 3 may enter this state, for example, when a connection to the network is suspended and may leave it using a procedure to resume the connection in the same or a different cell 9.

[0064] As described in more detail below, UEs 3 operating in idle and inactive modes are generally required to monitor a paging occasion (PO), for example by decoding the PDCCH and corresponding PDSCH for any paging message, within each UE DRX cycle.

[0065] Moreover, in the case of low Signal to Interference Noise Raito (SINR), the UE 3 could potentially need to wake up a relatively long time (e.g., 60 msec) before the paging occasion in order: to decode multiple SS bursts to achieve time and frequency synchronization; to perform automatic gain control (AGC) adjustment; and to identify the respective SSB of the serving cell 9 and of the neighbouring cell 9 required to perform associated measurements.

[0066] < Frame Structure > 　　Referring to Fig. 2, which illustrates the typical frame structure that may be used in the communication system 1, the RAN node 5 and UEs 3 of the communication system 1 communicate with one another using resources that are organised, in the time domain, into frames in this case of length 10ms. Each frame comprises ten equally sized subframes of 1 ms length. Each subframe is divided into one or more slots comprising 14 (or in some cases 12) orthogonal frequency-division multiplexing (OFDM) symbols of equal length.

[0067] 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. 　　Table 1 - 5G Numerology

[0068] Fig. 3 illustrates the resource grid of a subframe shown in Fig. 2 (which may be equivalent to one or more slots). As shown in Fig. 2, the subcarrier spacing, and the number of OFDM symbols within a subframe varies depending on the numerology. A single block shown in Fig. 3 corresponds to a single RE and this is the smallest unit of the resource grid and is made up of one subcarrier in the frequency domain and one symbol in the time domain. A resource block 25 is defined only for the frequency domain and is defined as twelve consecutive subcarriers in the frequency domain in one symbol.

[0069] < Control Information > 　　In the communication system. The RAN node 5 is configured to transmit control information to the UE 3 using one or more control resource sets (CORESETs). A CORESET is a set of time-frequency resources within which the UE 3 can search for DCI transmitted by a RAN node 5 on a PDCCH. A CORESET is analogous to the control region at the start of subframes in earlier generations of communication technology. Unlike earlier generations, however, in which the frequency domain of the control region typically corresponded to the total system bandwidth, the frequency domain location for CORESET is localised to a specific region in the frequency domain and has a variable width that can be set to any suitable value (typically in multiples of six resource blocks where each resource block comprises twelve subcarriers in the frequency domain).

[0070] A number of different DCI formats can be used by the RAN node 5, depending on requirements, for transmission on a PDCCH corresponding to one of the PDCCH candidates in one of the search spaces configured for a given UE 3. For example, the RAN node 5 may be able to transmit DCI using one or more of the currently standardised DCI formats as set out in Table 2. 　　Table 2 - DCI Format Summary

[0071] Different DCI formats may or may not have the same DCI size. Moreover, DCI may be addressed (scrambled) using different radio network temporary identifiers (RNTIs) that the UE 3 may monitor for. Typically, the UE 3 is capable of monitoring up to three different DCI sizes for DCI formats using a cell RNTI (C-RNTI) - typically used as an identifier for scheduling purposes. Additionally, the UE 3 is typically capable of monitoring one additional DCI size using other RNTIs for specific purposes (e.g., a slot format indication RNTI (SFI-RNTI), interruption RNTI (INT-RNTI), or the like). This constraint is sometimes referred to as the "3+1" size budget and is imposed because a DCI scrambled with a C-RNTI is, generally, more time critical than a DCI scrambled with a RNTI used for another specific purpose, and so requires the UE 3 to decode it promptly in order to be able to process the scheduled data transmission.

[0072] To take account of the constraint imposed by the DCI size budget, the sizes of some DCI formats may be aligned by padding, truncation, and / or determining a frequency domain resource assignment field differently.

[0073] The UE 3 may monitor a set of PDCCH candidates in one or more control resource sets (CORESETs) on an active DL bandwidth part, where monitoring implies decoding each PDCCH candidate according to the monitored DCI formats. The number of blind decodes (BDs) may be restricted on a per carrier basis of a serving cell. The number of BDs may refer to the number of monitored PDCCH candidates or the number of PDCCH candidates the UE 3 is capable of decoding within a certain time frame, such as a slot or span of consecutive symbols in a slot. As an example, at a 15 kHz subcarrier spacing (SCS), the maximum number of BDs per slot per serving cell 9 supported by the UE 3 may be 44 BDs.

[0074] < On-Demand SSB in the context of Carrier Aggregation (CA) > 　　In the communication system 1, increases in bandwidth, and thereby bitrate can be achieved through carrier aggregation (CA), whereby multiple frequency blocks, i.e., component carriers (CCs), are assigned to the same UE 3 for use. Each CC in turn serves a cell which provides a particular bandwidth and set of services to the UE 3. For example, in CA each UE 3 has a first CC that provides a primary cell (PCell) that carries traffic and RRC signalling messages and may additionally any number of other CCs that each provide their own corresponding secondary cell (SCell) which carry traffic alone. The SCells are optional, and are added, removed, and / or reconfigured are required by the UE 3 and the network.

[0075] In CA, when initially scanning for a cell to camp on each UE 3 scans for a PCell. The PCell is serves as the main point of communication between the UE 3 and the RAN node 5 and is responsible for all control information signalling (e.g., RRC Configuration signalling), non-access stratum (NAS) signalling, and the like, between the UE 3 and the network, as well as initial data transmissions. The PCell typically offers a high bandwidth for low latency data transmission. It will be appreciated that when initially scanning for a PCell to camp on each UE 3 searches for SSB as described previously to enable efficient cell searching for, and initial access to the PCell.

[0076] As and when required, the UE 3 may be triggered to search for, and camp on one or more secondary cells (SCells) to provide additional capacity and adaptability in the network. For example, the UE 3 may be triggered to search for, and camp on one or more SCells to provide extra bandwidth when the network is experiencing high data traffic or congestion. Additionally, or alternatively, SCells may be camped on to provide specific specialist services, for example, the UE 3 may camp onto a SCell that caters for Internet-of-Things (IoT) devices, high-definition data streaming, or the like.

[0077] The UEs 3 may be configured to camp onto SCells using a so-called 'SSB-less' procedure, where an SSB from the PCell is used for time / frequency synchronization, layer-1 (L1) / layer-3 (L3) measurements, SCell activation procedures, and the like. However, such an SSB-less procedure is most appropriately suited to scenarios where the CA is intra-band e.g., the PCell and the SCells operate on different frequencies within a specific frequency band such as the FR1 band (e.g., DL: 150 MHz to 7650 MHz, UL: 2300 MHz to 29250 MHz).

[0078] A group of serving cells associated with a master RAN Node 5 may be referred to as a master cell group (MCG). The MCG typically comprises a so called special cell (SpCell) which is the PCell (Primary Cell), and one or more SCells. A group of serving cells 9 associated with a secondary RAN Node 5 may be referred to as a secondary cell group (SCG). The SCG typically comprises an SpCell, which is known as a primary SCell (PSCell) in this case, and one or more SCells.

[0079] It will be appreciated that where the CA is inter-band e.g., the PCell and the SCells operate on different frequencies within different frequency bands such as the FR1 band (e.g., DL: 150 MHz to 7650 MHz, UL: 2300 MHz to 29250 MHz) and FR2 band respectively (e.g., DL / UL: 28 GHz and 29 GHz) SSB-less procedures for camping onto SCells may prove difficult as the time / frequency synchronization information (and the like) associated with the PCell on FR1 may not be appropriate for the SCells on FR2. In such cases the use of dedicated SSBs for SCells (e.g., on-demand SSBs for SCells) may be beneficial to ensure appropriate SCell activation procedures and RRM measurement procedures are performed for the SCell, and that correct SCell timing synchronization is achieved.

[0080] In such scenarios each UE 3 may be configured to search for SSBs associated with SCells when scanning for SCells to camp on and to decode the associated PBCH before proceeding to decode other system information transmitted on the PDSCH as described above, rather than rely on SSBs associated with the PCell. Given that SCells are not typically used by UEs 3 all the time, each UE 3 may be configured to perform on-demand SSB searching to search for SSBs associated with SCells only when the UE 3 (or network) decides that it wishes to utilise one or more SCells.

[0081] There are a number of scenarios to which such on demand SSB transmission for an SCell may be appropriate. For example, a scenario involving a downlink only SCell that is otherwise without SSB transmission but with tracking reference signals (TRS) / aperiodic TRS (A-TRS) DL transmissions, a scenario involving an SCell that is otherwise without SSB transmission and without any other downlink transmissions, but with uplink reception at the NW side), and / or the like.

[0082] On-demand SSB transmission may be enabled semi-statically or dynamically. For example, common channel adaptation and / or on-demand SSB may be enabled via dedicated RRC signalling on a PCell and / or PSCell if the UE has a PCell and / or PSCell connection. On-demand SSB may be enabled via system information (e.g., where the content of system information includes a carrier indication field to indicate the applicable carrier / cell for the enabling of on-demand SSB transmission). On-demand SSB may be enabled via a DCI with an appropriate DCI format (e.g., DCI format 1_0 with a cyclic redundancy check (CRC) scrambled with a system information RNTI (SI-RNTI), for example that includes a carrier indication field to indicate the applicable carrier / cell for the system information to be transmitted.

[0083] < General DTX / DRX > 　　The UE 3 may be configured to operate using a discontinuous reception (DRX) method. In a DRX method, the UE 3 is configured with a DRX configuration that includes a DRX pattern and a periodicity (DRX cycle) and optionally a number of DRX cycles. The DRX pattern defines "ON durations" in which the UE 3 is configured for receiving transmissions and "OFF durations" in which the UE 3 is not configured for receiving transmissions (e.g., transmissions from a RAN node 5). During the OFF durations the physical layer processing may be turned off within the UE 3. Advantageously, the energy consumption of the UE 3 is reduced in the periods in which the UE 3 is not configured for receiving transmissions.

[0084] The UE 3 is typically provided with its DRX configuration by or via the RAN node 5. A DRX configuration provided to the UE 3 (for example, using a DRX configuration information element (IE) included in a transmission from the RAN node 5 to the UE 3) may include, as mentioned above, an indication of a time period (OFF duration) for which the UE 3 is to be configured in a state in which the UE 3 does not receive and decode downlink transmissions, and an indication of a time period (ON duration) for which the UE 3 is to be configured for receiving downlink transmissions (e.g., a multicast or unicast transmission from the RAN node 5). The DRX configuration may also include a time offset, which may be useful for controlling the relative timing of the DRX configurations of different UEs 3 (e.g., to synchronise or offset the DRX patterns). The DRX configuration may also include an indication of a time period in which the UE 3 is to remain configured for receiving transmissions following the reception of a PDCCH.

[0085] The ON duration may also be referred to as the 'DRX active time', and the OFF duration may also be referred to as a 'sleep period', or a 'DRX inactive time'. An example of a DRX pattern having an ON duration of t1, and an OFF duration of t2, and which is repeated in accordance with a DRX cycle is illustrated in Fig. 4.

[0086] DRX may be configured per UE 3 by the network (e.g., via any suitable signalling from the RAN node 5). For example, the timing and / or duration of the ON durations in the DRX cycle may be different for different UEs 3. During the OFF durations, the UE 3 may be configured to not monitor a PDCCH but may initiate an uplink transmission based on configured resources (for example, using a PUCCH, a random access channel (RACH), scheduling request (SR) or a configured grant PUSCH (CG-PUSCH)). During an OFF duration, the system may be configured for no transmission / reception between the UE 3 and the RAN node 5 in a corresponding cell 9. The RAN node 5 may nevertheless be configured for reduced or limited transmission / reception in the cell 9 during the OFF duration of the DRX cycle. For example, the RAN node 5 may be configured to transmit only a subset of periodic signals or channels, such as common channels / signals or UE-specific channels / signals that would normally be transmitted in the cell 9.

[0087] DRX may be used when the UE 3 is in an RRC idle mode or when the UE 3 is in an RRC connected mode. For example, DRX may be used when the UE 3 is in an RRC idle mode to control the monitoring of paging messages transmitted by the RAN node 5. This advantageously prevents the UE 3 from monitoring all of the PDCCH transmission opportunities, thereby reducing the energy usage of the UE 3. Similarly, DRX may be used when the UE 3 is in the RRC connected state (referred to as connected mode DRX or 'C-DRX') to reduce the energy usage of the UE 3, for example by configuring periods in which the UE 3 is not required to monitor a PDCCH.

[0088] Within a C-DRX cycle, when the UE 3 is in an RRC connected state, the UE 3 periodically monitors the PDCCH during the ON durations, and does not monitor PDCCH outside of the ON durations (i.e., in the DRX inactive periods), thereby beneficially reducing the power consumption of the UE 3. Currently, during a C-DRX inactive time, the UE 3 is allowed to initiate an uplink transmission based on configured resources (for example, using a PUCCH, a random access channel (RACH), scheduling request (SR) or on a configured grant PUSCH (CG-PUSCH)).

[0089] A DRX configuration may also include a long DRX cycle in which the time between the ON durations is relatively large (t2 shown in Fig. 4 is relatively large), and a short DRX cycle in which the time between the ON durations is relatively small (t2 shown in Fig. 4 is relatively small). Whilst the long DRX cycle improves the energy efficiency of the system (because the overall percentage of time in which the UE 3 is in the ON state is smaller), latency of communications may be increased because the RAN node 5 cannot communicate with the UE 3 via downlink transmissions when the UE 3 is in the sleep state (the DRX inactive state). When the UE 3 is configured to use DRX after a period of inactivity following a data transfer, the UE 3 may be configured to initially use the short DRX cycle configuration, and after a further period of time (which may be defined by a Short DRX Cycle timer) the UE 3 may then operate using the long DRX cycle configuration. The short and long DRX configurations may be indicated to the UE 3, for example, using any suitable signalling from the RAN node 5 (or alternatively could be preconfigured in the UE 3).

[0090] Whilst DRX has been described above with reference to discontinuous reception performed by the UE 3, a similar DTX pattern can be defined to control the discontinuous transmission of data by the UE 3. When defined, the UE DTX pattern typically overlaps with the UE DRX pattern - so that when the UE 3 is not receiving data it is also normally not transmitting data.

[0091] < Paging > 　　The UE 3 in idle / inactive typically wakes up to monitor one paging occasion (PO) per DRX cycle for paging from the network. Where there are multiple UEs 3 in a cell 9 they can be divided into different paging groups such that each group of UEs 3 in a paging group monitors a different PO to help distribute the load generated by the paging procedure. To identify it paging occasion, the UE 3 has to first identify its paging frames (PFs). PFs are defined by the system frame number (SFN) which satisfy the equation: where: 　　SFN is the system frame number corresponding to a PF; 　　PFoffsetis a time domain offset in terms of radio frames; 　　T is the DRX cycle in radio frames; 　　N is the total number of paging frames during a DRX cycle; and 　　UEIDis an identifier of the UE based on the UE's serving temporary mobile subscriber identity (S-TMSI), e.g. a 5G-S-TMSI for NR.

[0092] The DRX cycle corresponds to the UE's default paging cycle (broadcast in system information (e.g. SIB1)) unless a UE specific value has been configured. Where the UE specific value has been configured the UE DRX cycle corresponds to the minimum of the default and the UE specific paging cycle. The UE specific paging cycle may, for example, be configured by an RRC message (e.g., an RRC release message when the UE 3 moves to an inactive mode). Moreover the UE 3 and AMF 10-1 can negotiate a UE specific paging cycle.

[0093] The UE 3 can then identify its POs based on the identified set of PFs. A PO index (is) is given by the following equation: where: 　　UEIDis the identifier of the UE based on the UE's serving temporary mobile subscriber identity (S-TMSI), e.g. a 5G-S-TMSI for NR; 　　N is the total number of paging frames during a DRX cycle; and 　　Ns is the number of paging occasions per paging frame.

[0094] The parameters required to calculate the PF and POs typically form part of a paging and control channel (PCCH) configuration (with the exception of the TMSI which may be allocated by the AMF) provided as part of system information (e.g. SIB1), for example, as part of a PCCH-Config IE or the like.

[0095] < Paging Early Indication PEI > 　　The UEs 3 and RAN node 5 of the communication system 1 are also mutually configured to enhance UE power saving in idle and inactive modes by means of the provision of a Paging Early Indication (PEI) from the RAN node 5 to the UE 3.

[0096] The PEI is used to help avoid unnecessary attempts to receive paging by the UE 3, in an associated paging occasion (PO) for that UE 3, by indicating to that UE 3 whether to decode paging (e.g., the associated PDCCH / PDSCH) in that PO. System information provided by the RAN node 5 may, for example, include a PEI configuration to be used by recipient UEs 3. UEs supporting PEI can then use the received PEI configuration to monitor PEI occasions (PEI-O) (e.g., one per UE DRX cycle). A common search space set (e.g., a so called 'Type2A-PDCCH' common search space set) may be configured for provision of DCI in accordance with an appropriate DCI format (e.g., DCI format 2_7 as indicated in Table 2) as those skilled in the art would be familiar. Thus, reception of the PEI can help the UE 3 to avoid waking up frequently, and unnecessarily, in idle / inactive mode to monitor paging occasions in which there is no paging.

[0097] Further UE power consumption optimisation can also be achieved by arranging the UEs 3 responsible for monitoring the same PO into a plurality of smaller groups (subgroups) within in a larger paging group. Specifically, to help reduce the incidence of false paging alarms when an unpaged UE 3 wakes up sufficiently to monitor a given PO due to another UE 3 within its paging group being paged, the PEI may additionally be configured to include an indication per subgroup, where the value specifies whether the UE 3 of the subgroup is required to monitor the PO. Accordingly, a given UE 3 of one subgroup is able to determine whether to avoid monitoring a given PO (even if the UE 3 of another subgroup is paged in that PO) based on the PEI indication.

[0098] When a PEI and subgrouping are configured, the subgrouping may, for example, be controlled by the core network 7, e.g., with the AMF 10-1 assigning a subgroup ID to the UE 3. Nevertheless, the subgrouping may be based on the UE's ID with an assigned subgroup ID being based on the UE ID and the total number of subgroups for the UE ID based subgrouping being defined by the RAN node 5. Several subgroups, up to an appropriate maximum (e.g., eight) subgroups (whether CN controlled, or UE ID based), may be configurable within a cell 9.

[0099] In addition to reductions in UE power consumption, additional TRS / CSI-RS type reference signals may be configured for paging reception for the UE 3 in an idle / inactive modes. The configuration these additional TRS resources may, for example, be provided via system information (e.g., in system information block type 17 ('SIB17'). The additional TRS can then be used for synchronisation to reduce the need to receive SS bursts for synchronisation purposes before PO reception and thus provides for a longer period of UE sleep within a DRX cycle, and in the number of times that the UE 3 is required to wake up in an idle / inactive mode.

[0100] It will be appreciated that the UE 3 (e.g., a legacy UE) that is not capable of monitoring a PEI-O, may simply monitor its paging occasions as normal without the commensurate power saving benefits.

[0101] As indicated in Table 2 DCI format 2_7 may be used for notifying both a PEI and a TRS availability indication for one or more UEs 3.

[0102] A DCI using DCI format 2_7 may, for example, have a CRC scrambled using a specific PEI RNTI and may include a paging indication field for indicating, for one or more paging occasions (and potentially one or more subgroups), whether or not paging is to occur in which. Each bit in the field may represent a PEI for one UE subgroup of a given paging occasion. It can be seen, therefore, that the paging indication may have a size equal to a number of configured paging occasions per PEI multiplied by a number of configured sub-groups per paging occasion.

[0103] Similarly, the DCI using DCI format 2_7 may, for example, include a TRS availability indication (e.g., of size 1, 2, 3, 4, 5, or 6 bits depending on configuration).

[0104] < Cell DTX / DRX > 　　As mentioned above, a RAN node 5 may also operate one or more of its cells in a DTX / DRX mode in substantially the same way as UE DTX / DRX - stopping the RAN node's transmissions and receptions during periods of time (OFF duration) when the RAN node 5 is inactive or asleep and resuming transmissions and receptions with the UEs 3 during periods of time (ON duration) when the RAN node 5 is active. The cell DTX / DRX configuration can be defined by a number of parameters such as the periodicity (DRX cycle), the start slot / offset, the ON (or 'active') duration (t1), the OFF (or 'inactive') duration (t2) and the number of cycles etc. as shown in Fig. 4.

[0105] The periodic cell DTX / DRX configuration may be explicitly signalled to the UEs 3. For example, in the communication system 1, one or more periodic cell DTX / DRX configurations comprising one or more periodic cell DTX / DRX patterns may be configured by UE specific (dedicated) signalling (e.g., RRC signalling). It will be appreciated, however, that cell DTX and cell DRX modes may be configured and operated separately (e.g., one (RRC) configuration set may be provided for the DL and another configuration set may be for provided for the UL). Nevertheless, (common) cell DTX / DRX may also be configured and operated together. It will be appreciated that the network may, or may not, allow legacy UEs 3 to access cells with Cell DTX / DRX. Cell DTX / DRX may be configured on a per serving cell 9 basis and may be applicable for different cells 9 in carrier aggregation (CA).

[0106] As a baseline, a given cell DTX / DRX configuration may be activated / deactivated implicitly by the configuration signalling (e.g., activated immediately once configured by an RRC configuration and deactivated once the RRC configuration is released). Nevertheless, a periodic cell DTX / DRX configuration may beneficially be explicitly activated / deactivated by L1 (or possibly L2) signalling and / or UE specific signalling.

[0107] Specifically, the communication system beneficially supports dynamic signalling (e.g., layer 1 (L1) / physical (PHY) layer signalling) by the RAN node 5, for at least activation / deactivation of a cell DTX and / or a cell DRX configuration at the UE 3 (e.g., in terms of enabling / disabling the cell DTX / DRX). In the exemplary communication system 1, this is achieved by means of L1 signalling that is addressable to one or more UEs 3 (e.g., using group common signalling), using a PDCCH, for cell DTX / DRX activation / deactivation. Specifically, DCI in accordance with a DCI format 2_9 may be used for the purpose of cell DTX and / or DRX configuration activation / deactivation of one or multiple serving cells 9 for one or more UEs 3, and / or for providing an NES-mode indication of a primary cell (PCell) for one or more UEs 3.

[0108] The DCI format 2_9 supports the provision of a respective indication of activation / deactivation of a DTX / DRX configuration, for each of a plurality of 'cell DTX / DRX' blocks (e.g., block number 1, block number 2, …, block number N). For each block, the DCI format 2_9 may include, for example, a respective DCI field that supports separate activation / deactivation for a DTX configuration, and for a DRX configuration, for the cell or cells corresponding to that block.

[0109] DCI format 2_9 may, for example, be transmitted with a CRC scrambled by an appropriate cell DTX / DRX radio network temporary identifier (e.g., 'cellDTRX-RNTI' or the like). DCI format 2_9 includes the configuration of each cell DTX / DRX block in turn (block number 1, block number 2,…, block number N), with the starting position, in the DCI, of a block associated with a serving cell 9 being determined by an appropriate parameter (e.g., a 'positionInDCI-cellDTRX' parameter) provided by appropriate higher layer (e.g., RRC) signalling to the UE 3.

[0110] For the UE 3 that is configured to monitor DCI 2_9 (with CRC scrambled by the cell DTX / DRX radio network temporary identifier, one or more blocks may be configured for the UE 3 by higher layer (e.g., RRC) signalling. For each configured block, a cell DTX / DRX indication field may be included in the DCI. This field may, for example, have two bits (one for each of DRX and DTX) if the cell DTX / DRX type is configured to be cell DTX and cell DRX (e.g., with the most significant BIT (MSB) corresponding to the cell DTX configuration and the least significant bit (LSB) corresponding to a cell DRX configuration). Otherwise, the field may have one bit if the cell DTX / DRX type is configured to be either cell DTX or cell DRX. An NES-mode indication field may also be included in the DCI with a single bit to indicate an NES-specific conditional handover execution condition.

[0111] The UE 3 that supports PEI configuration will typically, therefore, monitor one PEI occasion per DRX cycle.

[0112] < NES related enhancements > 　　Beneficially, the communication system 1 includes one or more NES related enhancements. These enhancements are focussed, in particular, on considerations associated with the adaptation of common channels / signals and include: 　　Enhancement to allow UE identification of what (and how) downlink and / or uplink signals / channels will be impacted during a cell DTX / DRX inactive; 　　Enhancement to UE procedures for receiving paging, SSBs, and / or TRS; 　　Enhancement related to cell search or cell reselection; 　　Enhancement to cell DTX / DRX for the UE 3 in idle / inactive mode including, e.g., to notify the UE of a cell DTX / DRX configuration; 　　Enhancement to support adaptation of cell DTX / DRX without deactivation e.g., to allow more efficient handling of traffic bursts; 　　Time domain enhancement of the PRACH procedure; and 　　Enhancement to support adaptation of a configuration for common channel / signal communication during a Cell DTX / DRX inactive duration.

[0113] It will be appreciated that the enhancements described are not mutually exclusive and all, or a subset of the enhancements, may be incorporated into a communication system 1 to provide a commensurate benefit. Nevertheless, the examples are also not reliant on one another and so may be implemented in the communication system 1 individually.

[0114] < Adaptation of signals / channels during cell DTX / DRX Inactive > 　　As mentioned above, the communication system may include one or more enhancements to allow UE identification of what (and how) downlink and / or uplink signals / channels will be impacted during a cell DTX / DRX inactive. Specifically, in a scenario in which common channel / signal adaptation is used by the RAN node 5 to reduce energy expenditure in the context of cell DTX / DRX, the RAN node 5 may provide, to UEs 3 having an associated capability, a configuration of the common channel / signal adaptation that may be used in an associated cell 9. Moreover, the RAN node 5 may provide an indication, to the UE 3 (connected, idle or inactive) of a particular level or configuration of common channel / signal transmissions that are to be used during an inactive / non-active or off period of a cell DTX / DRX cycle. This will now be described in more detail with reference to Fig. 5, which is a simplified sequence diagram illustrating configuration / indication of channel / signal adaptation that may be employed in the communication system 1.

[0115] As seen in Fig. 5, a configuration of a common channel / signal adaptation, for cell DTX / DRX, may be provided to the UE 3 when it has an active connection (e.g., RRC) via dedicated (e.g., RRC) signalling (as indicated at S522).

[0116] Nevertheless, beneficially, one or more common channel / signal adaptation configuration may be indicated to, and hence made applicable at, both connected mode UEs 3 and idle / inactive mode UEs 3. Specifically, as seen at S524, when cell DTX / DRX is configured, DCI using an appropriate DCI format (e.g., DCI 2_9) and / or a SIB (which may be a new SIB, SIBx, or a modification to an existing SIB) may be used to indicate a level of downlink and / or uplink common channel / signal transmission that may occur specifically during a cell DTX / DRX inactive period.

[0117] For example, DCI and / or a SIB may be configurable to indicate that any of a number of different alternative configurations of reduced (or conventional) downlink channels / signalling (e.g., downlink reference signals, SSB transmission occasions and / or the like) and / or uplink channels / signalling (e.g., uplink reference signals, RACH transmission occasions and / or the like) are enabled or disabled. It will be appreciated that these alternative configurations may have been preconfigured or may be configured by dedicated (RRC) signalling when the UE 3 had a connection.

[0118] For example, the DCI and / or a SIB may be configured to include a two (or more) bit field to indicate which, of a corresponding number of, downlink / uplink common channel / signal transmission levels may be used. An example of a possible two bit field is shown in Table 3. It will be appreciated that a greater granularity of downlink and uplink transmission levels to be used in a cell DTX / DRX inactive periods may be signalled using additional bits albeit at the expense of signalling overhead.

[0119] Table 3 - Common cannel / reference signal transmission level

[0120] As seen in Table 3 the indication may indicate that on demand transmissions may be used (e.g., in the downlink) as part of the common channel / signal adaptation in the cell DTX / DRX inactive period. It will be appreciated that, in accordance with this, SSBs and TRS may be transmitted on demand and / or with reduced transmission during cell DTX / DRX inactive duration. For example, these on-demand transmissions may comprise on-demand SSB and / or TRS transmission (e.g., for SSB transmission adaptation by extending the on-demand SSB transmission described above to use in the cell DTX / DRX inactive duration).

[0121] It will be appreciated that, beneficially, for a cell in a non-active / inactive duration of the cell DTX / DRX configuration, if no SSB, or reduced (or on demand) SSB is transmitted, demodulation reference signals (DMRS) may be transmitted by the RAN node 5 during a cell DTX inactive duration so that the UE 3 is still able to detect / discover the cell 9.

[0122] It will be appreciated that, for reduced transmission, dedicated (e.g., RRC) signalling may be used to configure, for example, that only the first SSB (and / or TRS) transmission occasion within a cell DTX / DRX active / non-active cycle is allowed to be used.

[0123] It will be appreciated that, for reduced transmission, SSB (and / or TRS) in one or more transmission occasions may effectively be turned off in a cell DTX non-active / inactive duration. For example the dedicated (e.g., RRC) signalling may be used to configure, for example, one transmission to be allowed every n occasions (e.g., for low mobility scenarios).

[0124] < UE procedures for receiving paging, SSBs, and / or TRS > 　　As mentioned above, the communication system 1 may include one or more enhancements to UE procedures for receiving paging, SSBs, and / or TRS.

[0125] < PEI Procedures > 　　A number of possible enhancements involving variation on PEI procedures will now be described in more detail with reference to Figs. 6 to 12.

[0126] Fig. 6 is a simplified sequence diagram illustrating a procedure involving the transmission of a paging early indication, in the event that the UE 3 is to be paged, that may be employed in the communication system 1.

[0127] Fig. 7 is a simplified sequence diagram illustrating a procedure involving the transmission of a paging early indication, in the event that the UE 3 is not going to be paged, that may be employed in the communication system 1.

[0128] Fig. 8 is a simplified illustration of the transmission of the paging early indication, shown in Fig. 6, during a cell DTX active period.

[0129] Fig. 9 is a simplified illustration of the transmission of the paging early indication, shown in Fig. 6, during a cell DTX inactive period.

[0130] In the procedures illustrated in Fig 6. and Fig. 7, the RAN node 5 is configured to provide, during a PEI-O, to the UE 3 having an associated capability, a PEI that indicates each of one or more subsequent UE DRX cycles, if the PO occasion for that UE DRX cycle falls within a cell DTX non-active period.

[0131] As seen in Fig. 6, when the PEI indicates that the UE 3 is to be paged (at S612), the UE 3 will subsequently wake up at the next paging occasion within the upcoming cell DTX / DRX active period, as seen at S614 (even if the next PO occasion for that UE DRX cycle falls within a cell DTX non-active period). It will be appreciated that the PEI may potentially be sent during a cell DTX active period (as seen in Fig. 8) or during a cell DTX inactive period (as seen in Fig. 9).

[0132] As seen in Fig. 7, when the PEI indicates that there is 'no paging' (i.e., the UE 3 is not going to be paged), at S712, the UE 3 the UE 3 will assume that there is no paging in the subsequent one or more POs to which the PEI relates (and possibly no associated SSB and / or TRS also) within the next cell DTX / DRX active period.

[0133] Alternatively, or additionally, the PEI indication may include a field for indicating that the subsequent one or more POs within a cell DTX non-active / inactive period will not be skipped. For example, to ensure, paging is maintained within a paging latency tolerance (and / or due to a low SINR).

[0134] Fig. 10 is a simplified sequence diagram illustrating another procedure involving the transmission of a paging early indication, in the event that the UE 3 is to be paged, that may be employed in the communication system 1.

[0135] As seen in Fig. 10, in this example when the UE 3 is sent the PEI, at S1012, the PEI includes the field for indicating that the subsequent one or more POs within a cell DTX non-active / inactive period will not be skipped. Accordingly, the UE 3 assumes that the next PO will not be skipped, and that paging will be sent, regardless of whether the PO is in a DTX non-active / inactive period. The UE 3 thus wakes up to receive the paging at S1014. Contrastingly, if the field for indicating that the subsequent one or more POs within a cell DTX non-active / inactive period will not be skipped is not present, the UE 3 can assume that the next PO within a cell DTX non-active period will be skipped.

[0136] Fig. 11 is a simplified sequence diagram illustrating a procedure in which a paging early indication occasion and a paging occasion are both skipped, in the event that the UE 3 is not going to be paged, that may be employed in the communication system 1.

[0137] Fig. 12 is a simplified illustration of the skipping of the paging occasion, shown in Fig. 11, during a cell DTX inactive period.

[0138] As seen in Fig. 11, alternatively, or additionally, if a PEI-O coincides with a cell DTX inactive duration, and there is no paging information, a PEI may not need to be transmitted and may thus be skipped (as seen at S1112). If a PEI is not received within a cell DTX inactive duration, the UE 3 may thus assume that the PO (and any associated SSB / TRS) for the corresponding cell DTX inactive duration is skipped (as seen at S1114, and in Fig. 11 and Fig. 12). If a PEI is not received for a cell DTX active duration, the UE 3 may, nevertheless, continue to monitor every PO within the cell DTX active duration (as seen at S1116 in Fig. 12).

[0139] Accordingly, in this example, an NES capable UE may only monitor a paging occasion in a cell DTX active time (if cell DTX is activated). It will also be appreciated that even if a PEI is not enhanced, paging occasions within a cell DTX non-active / inactive time may be skipped and an NES capable UE may only monitor paging occasions in a cell DTX active time (if cell DTX is activated).

[0140] Whilst this has the potential to impact earlier (legacy) UEs 3, including UEs 3 without a Cell DTX capability, such UEs 3 may simply fail to acquire paging several times during a cell DTX inactive period.

[0141] < Discontinuous Paging > 　　The communication system 1 may also support one or more NES enhancements to paging mechanisms, in the context of Cell DTX / DRX, that do not rely on the UE's PEI reception capability, although it will be appreciated that the enhancements may, nevertheless, be applicable to both PEI capable and PEI non-capable UEs.

[0142] Specifically, when Cell DTX is configured and activated, the RAN node 5 adjusts the UE's PO into cell DTX active period. This also beneficially allows the UE 3 (that has an associated capability) not to attempt to receive any paging in the normal POs configured for that UE 3 that fall within the DTX inactive period (e.g., where the UE 3 is capable of being made aware of the cell DTX configuration and the fact that the DTX configuration is active in the cell 9).

[0143] There are a number of different techniques for implementing an NES enhancement to the paging mechanism. It will be appreciated that the RAN node 5 and the UE 3 may be mutually configured to be able to implement all or a subset of one or more of these different techniques.

[0144] In one technique, the RAN node 5 effectively delays any PO for the UE 3, that would otherwise occur during a cell DTX inactive duration, to the nearest PO in the following cell DTX active period. Similarly, the UE 3 that is aware of the cell DTX configuration (and the fact that the DTX configuration is active in the cell 9) can determine the delayed PO to be the nearest PO in the following cell DTX active period.

[0145] In another alternative or additional technique, the RAN node 5 may delay any PO for the UE 3 to a PO that is determined based on the UEs ID (e.g., the S-TMSI). Specifically, the RAN node 5 may delay any POs for the UE 3, that would otherwise occur during a cell DTX inactive duration, to the Nth nearest POs in following active period, where N is given by, for example: or where: 　　X is a total number of paging occasions in the next active period; and 　　Y is a predefined (or (pre)configured) value.

[0146] Similarly, the UE 3 that is aware of the cell DTX configuration (and the fact that the DTX configuration is active in the cell 9) can determine the delayed PO to be the Nth nearest POs in following active period based on the above.

[0147] In another technique, the RAN node 5 may reschedule all UEs 3 (of all sub-groups, e.g., based on their sub-group indexes) for which data / paging information is pending for communication on the PDCCH / PDSCH in a paging occasion in a current cell DTX non-active / inactive duration, to the first PO in the next cell DTX active duration.

[0148] In another technique, the RAN node 5 may adjust the value N and / or of Ns used by the UE 3 in the calculation of its own PFs / POs (as described above). Specifically, for example, N (which, as indicated above, conventionally represents the total number of paging frames in T) may be adjusted to equal the total number of paging frames that are in T, and that are also in the cell DRX active period. Alternatively, for example, Ns (which, as indicated above, conventionally represents the number of paging occasions per PF), may be adjusted to equal the total number of paging occasions that are in a PF, and that are not also in the cell DRX non-active / inactive period.

[0149] < Cell Selection / Reselection > 　　In the communication system 1 idle / inactive mode UEs 3 may perform measurements of the signal strength / signal quality of cells 9 in its vicinity to determine whether there is a cell exhibiting a transmission power that is strong enough to be recognised / detected by the UE 3 for the purposes of cell selection / reselection.

[0150] Typically, for example, the UE 3 will measure the RSRP (referred to as SS-RSRP) of synchronisation signals transmitted as part of the SSBs broadcast in a cell 9. Similarly, the UE 3 will measure the RSRQ (referred to as SS-RSRQ) of synchronisation signals transmitted as part of the SSBs broadcast in a cell 9. To a cell to be selectable for the purposes of cell (re)selection the RSRP measurements for that cell 9 have to exceed a minimum RSRP threshold (typically referred to as 'Qrxlevmin') potentially by an offset. Similarly, the RSRQ measurements for that cell 9 have to exceed a minimum RSRQ threshold (typically referred to as 'Qqualmin') potentially by an offset. The thresholds are typically configured via system information (e.g., SIB1) broadcast in the corresponding cell 9.

[0151] As mentioned above, the communication system 1 may include one or more enhancements elated to cell search or cell reselection.

[0152] In more detail, where a cell 9 is subject to cell DTX / DRX, an idle / inactive mode UE 3 may perform cell (re)selection based on measurements that are, mostly, taken during the cell DTX active duration (e.g., because fewer or no SSBs are broadcast during cell DTX inactive periods).

[0153] Beneficially, in the communication system 1, a scaling factor may be applied to a measurement threshold (e.g., for SS-RSRP power) used for cell (re)selection to take account of the reduced SSB based RSRP samples. By way of example only, the scaling factor may, for example, be a value in the range of 0.0 to 1.0, with a typical value of 0.5 (plus or minus 0.1).

[0154] The scaled measurement threshold may, for example, be provided to the UEs 3 in system information when cell DTX / DRX is operating in the corresponding cell 9. Alternatively, or additionally, the scaling factor may be provided in system information for the UE 3 to apply if the UE 3 is aware that cell DTX / DRX is operating in the corresponding cell 9.

[0155] < Cell DTX / DRX in Idle / Inactive mode > 　　As mentioned above, the communication system 1 may include one or more enhancements to cell DTX / DRX for the UE 3 in idle / inactive mode including, e.g., to notify the UE 3 of a cell DTX / DRX configuration.

[0156] A number of possible enhancements to cell DTX / DRX for the UE 3 in idle / inactive mode will now be described in more detail, by way of example only, with reference to Fig. 13. It will be appreciated that the RAN node 5 and the UE 3 may be mutually configured to be able to implement all or a subset of one or more of these different enhancements.

[0157] Fig. 13 is a simplified sequence diagram illustrating a number of possible ways to notify the UE 3 of activation (or enablement) and / or deactivation (or disablement) of a cell DTX / DRX configuration that may be employed in the communication system 1.

[0158] In one enhancement, the RAN node 5 is able to provide, to the UEs 3 in a cell 9 that it operates, an indication for enabling or disabling a cell DTX and / or cell DRX in system information (e.g., a new, or modified existing, SIB) as seen at S1312. The indication may, for example, comprise a two-bit indication with one bit for enabling / disabling (activating / deactivating) cell DTX and another bit for enabling / disabling cell DRX (e.g., a '1' for enabling and '0' for disabling or vice versa). It will be appreciated that one or more cell DTX / DRX patterns may be configured by this or other system information (e.g., in the new, or modified existing, SIB mentioned above or in a different SIB) along with the cell DTX / DRX activation. Alternatively, or additionally, an idle / inactive UE 3 that has had a previous RRC connection may have been configured by an RRC message (e.g., an RRC reconfiguration message) with one or more cell DTX / DRX patterns that can be activated / deactivated (enabled / disabled).

[0159] It will be appreciated that, in some scenarios, it may be beneficial for the same cell DTX / DRX pattern to be used for the UE 3 in an idle or inactive mode as is configured for the UE 3 in a connected or active mode. In this scenario DCI may be used for indicating activation / deactivation of the cell DTX / DRX pattern to the UE 3. For example, an idle / active mode UE 3 may be configured to monitor for DCI that uses DCI format 2_9 (which, as indicated in Table 2, is for activating or de-activating the cell DTX and / or DRX configuration of one or multiple serving cells 9 for one or more UEs 3) as seen at S1314. Alternatively, or additionally, DCI using a modified version of DCI 2_7 (which is monitored for and received by idle / inactive UEs 3 in PEI-Os) as seen at S1316. For example, the PEI field of DCI format 2_7 could be extended to include a cell DTX / DRX indication for activating / deactivating the configured cell DTX and / or cell DRX pattern.

[0160] Nevertheless, it will be appreciated that, in some scenarios, it may be beneficial for a dedicated cell DTX / DRX pattern to be configured that is applicable specifically to UEs 3 in an RRC idle / inactive mode. For example, the dedicated cell DTX / DRX pattern may be configured as 'pattern 0' among a plurality of configured cell DTX / DRX patterns and one or more cell DTX / DRX patterns (for one or more cells 9 operated by the RAN node 5) may be configured as another pattern of the plurality of configured cell DTX / DRX patterns. Beneficially, by specifying multiple DTX / DRX patterns on the same serving cell 9, UEs 3 in idle / inactive mode may be assigned a default cell DTX / DRX pattern with longer cell DTX / DRX periodicity thereby providing for enhanced power savings. It will be appreciated that one or more dedicated cell DTX / DRX patterns applicable specifically to UEs 3 in an RRC idle / inactive mode could, for example, be configured at the start of (e.g., the first pattern in) a list of configured patterns. Alternatively, or additionally, or more dedicated cell DTX / DRX patterns applicable specifically to UEs 3 in an RRC idle / inactive mode may be configured by system information, with one or more other cell DTX / DRX patterns (for connected mode UEs 3) being configured by RRC. A configured dedicated cell DTX / DRX pattern applicable specifically to UEs 3 in an RRC idle / inactive mode could then be subsequently activated / deactivated by, for example, the activation / deactivation DCI (e.g., DCI 2_9).

[0161] < Cell DTX / DRX without deactivation > 　　As mentioned above, the communication system 1 may include one or more enhancements to support adaptation of cell DTX / DRX without deactivation, for example to allow more efficient handling of traffic bursts.

[0162] This will now be described in more detail, by way of example only, with reference to Fig. 14, which is a simplified sequence diagram illustrating a number of possible techniques for supporting cell DTX / DRX adaptation without deactivation that may be employed in the communication system 1. It will be appreciated that the RAN node 5 and the UE 3 may be mutually configured to be able to implement all or a subset of one or more of these different techniques.

[0163] Referring to Fig. 14, rather than deactivate cell DTX / DRX when traffic load increases temporarily, for example as a result of traffic bursts, the communication system 1 implement ones or more enhancements for supporting appropriate (temporary) adaptation of a cell DTX / DRX pattern (e.g., to allow for more efficient handling of the traffic bursts).

[0164] Specifically, upon traffic arrival for which cell DTX / DRX is appropriate (e.g., traffic of a high priority service or indicative of a particularly large traffic burst) at S1410, the UE 3 may indicate, to the RAN node 5, that cell DTX / DRX is required / requested as S1412. This may be done using an explicit indication (e.g. 'cell DTX / DRX is required / requested') or an implicit indication (e.g., of indicating the arrival of traffic for a high priority service or large traffic burst). Any suitable message may be used for this indication, for example a wake-up signal (WUS), buffer status report (BSR), a scheduling request (SR) or any another suitable RRC message with the additional information element. On receipt of the indication from the UE 3, the RAN node 5 may, at S1414, cancel one or more cell DTX / DRX non-active / inactive durations resulting in the affected cell DTX / DRX non-active / inactive durations becoming an active duration e.g., for a configured number of cell DTX / DRX cycles. The number of cell DTX / DRX cycles to be cancelled may, for example, be configured in advance via an information element provided using appropriate RRC signalling (e.g., an RRC reconfiguration message or the like). For example, the cell DTX / DRX configuration information element (e.g., 'cellDTXDRX-Config' IE) typically provided as part of a serving cell configuration in an RRC reconfiguration message (or potentially in another RRC message) may be enhanced to include an information element indicating the number of cell DTX / DRX cycles to be cancelled (e.g., a 'numCellDTXDRX-CyclesToCancel' IE).

[0165] A simplified example of an Abstract Syntax Notation One (ASN.1) representation of a possible implementation of the modified cell DTX / DRX configuration information element is provided below by way of illustration only (only showing relevant parts of the information element): 　　cellDTXDRX-Config-r19 ::= 　　　　{ 　　　　numCellDTXDRX-CyclesToCancel INTEGER(0..9), 　　　　… 　　　　}

[0166] The RAN node 5 may, alternatively, or additionally, also indicate that one or more cell DTX / DRX non-active / inactive durations has / will become a cell DTX / DRX active duration for a specified period as indicated at S1416. It will be appreciated that this indication may be sent by the RAN node 5 as a response to the indication from the UE 3 (e.g., at S1412) where such an indication is implemented in the communication system 1. Nevertheless, the indication may be sent by the RAN node 5 independently for some other reason. The period may, for example, be specified as a length, or number of cell DTX / DRX non-active / inactive durations to be measured / counted.

[0167] The indication sent at S1416 may be provided using any mechanism, for example as part of DCI that the UE 3 monitors for. The indication from the RAN node 5 may, for example, be sent via DCI format 2-9, or via a field in a scheduling DCI format (e.g., if only targeting a UE specific traffic burst). It will be appreciated that different DCI formats could be used for providing the indication depending on requirements (e.g., depending on whether a specific individual UE 3 or a group of UEs 3 is being addressed).

[0168] The indication may be configurable as a simple one-bit indication to indicate that a previously configured number of cell DTX / DRX inactive cycles are / will be cancelled (e.g., the number of cell DTX / DRX cycles to be cancelled configured by an RRC message as described above). Nevertheless, the indication may alternatively or additionally be configurable as an indication with a plurality of bits (e.g., two) to indicate a binary value that represents / maps to one of several (e.g., four) different specific numbers of cell DTX / DRX cycles to be cancelled.

[0169] A simplified example of an ASN.1 representation of a possible implementation of the indication from the RAN node 5 as part of DCI format 2_9 is provided below by way of illustration only (only showing relevant parts of the information element): 　　DCI format 2-9 　　　　{ 　　　　cancelCellDTXDRXInactiveCycles / / 1 bit: cancel a default value or that specified in RRC configuration 　　　　 / / 2 bits: indicate 1 out of 4 values 　　　　… 　　　　}

[0170] < PRACH adaptation in the time domain > 　　As mentioned above, the communication system 1 may include one or more enhancements to support time domain enhancement of the PRACH procedure in the context of cell DTX / DRX.

[0171] This will now be described in more detail, by way of example only, with reference to Fig. 15, which is a simplified illustration of the operation of RACH occasions, in the context of cell DTX / DRX (specifically cell DRX), that may be used in the communication system 1.

[0172] A RACH occasion represents a specific period of time (and frequency region) within which the UE 3 can initiate an attempt to access the network by sending an initial access request (e.g., comprising a RACH preamble and also referred to as 'message 1' or simple 'msg1') on the RACH. During these RACH occasions, the RAN node 5 needs to be able to receive any initial access request transmitted by the UE 3. The time domain locations (resources) for transmission of the RACH preamble (the RACH occasions) are determined using a PRACH configuration index (e.g., 'prach-ConfigurationIndex') which points to a row in a standardised PRACH configuration table. This row defines, for example, the radio frames within which RACH occasions are present by means of two parameters 'x' and 'y' where the radio frames containing a RACH occasion is given by the system frame number (nSFN) which satisfies the equation:

[0173] Referring to Fig. 15, the communication system 1 may implement an enhancement in which a RACH occasion is effectively treated as being 'invalid' and hence skipped (as seen at S1512) if that RACH occasion falls within cell DRX inactive duration. Beneficially, therefore, a RAN node 5 does need to receive a RACH preamble in, and hence does not schedule a corresponding PDCCH / PDSCH for, those invalid RACH occasions in a cell DRX inactive duration. This therefore provides for additional energy saving efficiency.

[0174] Similarly in this example, as seen in Fig. 15, the UE 3 will only send an initial access request at a RACH occasion during a cell DRX active time (as seen at S1514) in a case where cell DRX is activated. Any RACH occasion during a cell DRX inactive time (as seen at S1512) is skipped.

[0175] < Adaptation common channel / signal configuration during Cell DTX / DRX inactive > 　　As mentioned above, the communication system 1 may include one or more enhancements to support adaptation of a configuration for common channel / signal communication during a cell DTX / DRX inactive duration.

[0176] A number of possible enhancements for supporting adaptation of a configuration for common channel / signal communication during a cell DTX / DRX inactive duration will now be described in more detail, by way of example only, with reference to Figs. 16 and 17. It will be appreciated that the RAN node 5 and the UE 3 may be mutually configured to be able to implement all or a subset of one or more of these different enhancements.

[0177] Fig. 16 is a simplified sequence diagram illustrating a method for supporting adaptation of a configuration for common channel / signal communication during a cell DTX / DRX inactive duration for a connected mode UE 3 that may be employed in the communication system 1.

[0178] As seen in Fig. 16, a common channel configuration specifically for the purpose of common channel adaptation in a cell DTX / DRX inactive duration may be signalled to a connected mode UE 3 as part of dedicated RRC signalling (e.g., an RRC reconfiguration message or the like) as seen at S1612.

[0179] It will be appreciated that the signalled common channel configuration represents a new / alternative common channel configuration compared to a standard / default common channel configuration that may be used when cell DTX / DRX is not active and / or during a cell DTX / DRX active period.

[0180] The use of the alternative common channel configuration may be applied automatically at the RAN node 5 / UE 3 upon cell DTX / DRX activation as indicated at S1614. Alternatively, or additionally, the RAN node 5 may be able to enable / disable use of the alternative configuration individually at the UE 3 via appropriate signalling (e.g., in an RRC message and / or via DCI) as seen at S1616.

[0181] The alternative configuration may, for example, include an alternative uplink common channel configuration. An alternative uplink common channel configuration may, for example, comprise an alternative PRACH configuration for configuring fewer (or different) RACH occasions by means of an alternative PRACH configuration index (e.g., 'prach-ConfigurationIndex' or the like).

[0182] The alternative configuration may, for example, include an alternative downlink common channel configuration. An alternative downlink common channel configuration may, for example, comprise an alternative paging configuration for configuring fewer (or different) paging occasions (e.g., by prolonging the default UE DRX cycle (T) and / or by configuring smaller values of 'N' and / or 'Ns' as described above in the section related to 'discontinuous paging'). An alternative downlink common channel configuration may, for example, comprise an alternative SSB configuration e.g., for configuring fewer SSBs in an SSB burst and / or a longer SSB periodicity.

[0183] It will be appreciated that it may be particularly beneficial, when cell DTX / DRX is applied in respect of an idle / inactive mode UE 3, in order to maximise the sleep time of the RAN node 5, to adopt all / most of the common signal / channel new / alternative configurations for cell DTX / DRX inactive durations.

[0184] Fig. 17 is a simplified sequence diagram illustrating a method for supporting adaptation of a configuration for common channel / signal communication during a cell DTX / DRX inactive duration for an idle / inactive mode UE 3 that may be employed in the communication system 1.

[0185] As seen in Fig. 17, in this example a common channel configuration specifically for the purpose of common channel adaptation in a cell DTX / DRX inactive duration may be signalled to an idle / inactive mode UE 3 as part of system information (e.g., in a new, or modified existing, SIB) as seen at S1712.

[0186] Referring to the RACH occasion enhancement described with reference to Fig. 15, in a case where a RACH occasion is considered valid only during a cell DRX active time a shorter RACH occasion period could potentially be configured to help ensure there are sufficient RACH occasions for beam sweeping and / or random access traffic during the cell DRX active time. Moreover, another PRACH configuration index corresponding to a much longer RACH period may be configured such that the cell DTX / DRX inactive duration is carefully avoided by implementation (i.e., there is no interaction with cell DRX when cell DRX is activated).

[0187] For example, the time domain position of RACH occasions may be aligned with the cell DTX / DRX configuration so that, for the purposes of the nSFN mod x = y equation described above, 'x' and 'y' may be configured with more flexible values, including relatively large values of 'x' (corresponding to the RACH period), for example x may be greater than 16 (e.g. 32, 64, etc…).

[0188] It will be appreciated that the cell DTX / DRX could be explicitly configured and activated for an idle / inactivate mode UE 3, together with the alternative common signal configuration described above. Nevertheless, effective cell DTX / DRX may be achieved by simply configuring the common channel activity (e.g., RACH occasions), as described above, to be aligned within the active duration of a cell DTX / DRX time window, hence effectively achieving cell DTX / DRX in idle mode implicitly.

[0189] A simplified example of an ASN.1 representation of a possible implementation of a downlink common channel configuration information element (which may be included in RRC signalling and / or system information) is shown below by way of example only (only showing relevant parts of the information element): 　　DownlinkConfigCommonForNES-r19 ::= SEQUENCE { 　　　　ssb-PositionsInBurst CHOICE { 　　　　　　 shortBitmap BIT STRING (SIZE (4)), 　　　　　　 mediumBitmap BIT STRING (SIZE (8)), 　　　　　　 longBitmap BIT STRING (SIZE (64)) 　　　　 } 　　　　ssb-periodicityServingCell ENUMERATED { ms5, ms10, ms20, ms40, ms80, ms160, spare2, spare1 } OPTIONAL, -- Need S 　　　　pcch-Config PCCH-Config, OPTIONAL, -- Need R 　　　　… 　　　　}

[0190] A simplified example of an ASN.1 representation of a possible implementation of an uplink common channel configuration information element (which may be included in RRC signalling and / or system information) is shown below by way of example only (only showing relevant parts of the information element): 　　UplinkConfigCommonForNES-r19 ::= SEQUENCE { 　　　　prach-ConfigurationIndex INTEGER (0..255), 　　　　msg1-FDM ENUMERATED {one, two, four, eight}, 　　　　msg1-FrequencyStart INTEGER (0..maxNrofPhysicalResourceBlocks-1), 　　　　} 　　　　}

[0191] < UE Capability > 　　It will be appreciated that the UE 3 may be configured for signalling its capability for supporting common channel adaptation in a cell DTX / DRX non-active / inactive duration to the RAN node 5. This may for example be signalled as part of a UE capability enquiry procedure in which the UE capability is provided to the RAN node 5 in response to a request for that UE capability from the RAN node 5. The UE capability may, for example, indicate the UE's capability for one or more of on-demand or reduced transmission of SSB, SIB1, TRS, paging or PRACH.

[0192] < User Equipment > 　　Fig. 18 is a schematic block diagram illustrating the main components of the UE 3 as shown in Fig. 1.

[0193] As shown, the UE 3 has a transceiver circuit 31 that is operable to transmit signals to and to receive signals from a RAN node 5 via one or more antennas 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 communication system 1 or from a removable data storage device (RMD), for example.

[0194] 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, and a communication control module 43.

[0195] The communication control module 43 is operable to control the communication between the UE 3 and its serving RAN node or RAN nodes 5 (and other communication devices connected to the RAN node 5, such as further UEs and / or core network nodes). The communication control module 43 is configured for the overall handling of 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 communication control module 43 is also configured for the overall handling of receipt of downlink communications via associated downlink channels (e.g., of DCI via a physical downlink control channel (PDCCH) and / or a physical downlink shared channel (PDSCH)) including both dynamic and semi-persistent scheduling (e.g., SPS). The communication control module 43 is responsible, for example: for determining where to monitor for downlink control information; for determining the resources to be used by the UE 3 for transmission / reception of UL / DL communications (including interleaved resources and resources subject to frequency hopping); for managing frequency hopping at the UE side; for determining how slots / symbols are configured (e.g., for UL, DL or full duplex communication, or the like); for determining which bandwidth parts are configured for the UE 3; for determining how uplink transmissions should be encoded and the like.

[0196] It will be appreciated that the communication control module 43 may include a number of sub-modules ('layers' or 'entities') to support specific functionalities. For example, the communication control module 43 may include a PHY sub-module, a MAC sub-module, an RLC sub-module, a PDCP sub-module, an RRC sub-module, etc.

[0197] The communication control module 43 is configured, in particular, to control the UE's communications, where applicable, in accordance with any of the methods described herein.

[0198] < RAN node > 　　Fig. 19 is a schematic block diagram illustrating the main components of the RAN node 5 for the communication system 1 shown in Fig. 1. As shown, the RAN node 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 antennas 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 RAN node 5 may also be coupled to other RAN nodes 5 via an appropriate interface (e.g. the so-called 'Xn' interface in NR). The RAN node 5 has a controller 57 to control the operation of the RAN node 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 RAN node 5 by, in this example, program instructions or software instructions stored within memory 59.

[0199] As shown, these software instructions include, among other things, an operating system 61, and a communication control module 63.

[0200] The communication control module 63 is operable to control the communication between the RAN node 5 and UEs 3 and other network entities that are connected to the RAN node 5. The communication 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 communication 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 communication 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.

[0201] It will be appreciated that the communication control module 63 may include a number of sub-modules (or 'layers') to support specific functionalities. For example, the communication 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.

[0202] The communication control module 63 is configured, in particular, to control the RAN node's communications, where applicable, in accordance with any of the methods described herein.

[0203] < Modifications and Alternatives > 　　As those skilled in the art will appreciate, a number of modifications and alternatives can be made to the above examples whilst still benefiting from the advantages that they provide.

[0204] It will be appreciated that a cell DTX / DRX pattern referred to above may be a dedicated cell DTX pattern, a dedicated cell DRX pattern, and / or a combined cell DTX / DRX pattern (i.e., used for both cell DTX and cell DRX).

[0205] It will be appreciated, 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.

[0206] In the above description, the UEs 3 and the RAN node 5 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 a corresponding device, 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.

[0207] In the above examples, 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 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 RAN node 5 or the UE 3 in order to update their functionalities.

[0208] 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.

[0209] The RAN node may comprise a 'distributed' RAN node having a central unit 'CU' and one or more separate distributed units (DUs).

[0210] 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.

[0211] 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.

[0212] 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.

[0213] 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.).

[0214] 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.).

[0215] 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.).

[0216] 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.).

[0217] A UE may, for example, be an electronic lamp, a luminaire, a measuring instrument, an analyser, 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.

[0218] 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)).

[0219] 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.

[0220] 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.

[0221] It will be appreciated that IoT technology can be implemented on any communication devices that can connect to a communication network for sending / receiving data, regardless of whether such communication devices are controlled by human input or software instructions stored in memory.

[0222] 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 4. This list is not exhaustive and is intended to be indicative of some examples of machine type communication applications.

[0223] Table 4

[0224] 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.

[0225] Further, the above-described UE categories are merely examples of applications of the technical ideas and examples described in the present document. Needless to say, these technical ideas and examples are not limited to the above-described UE and various modifications can be made thereto.

[0226] Various other modifications will be apparent to those skilled in the art and will not be described in further detail here.

[0227] Although the present disclosure has been described with reference to the example embodiments, the present disclosure is not limited to the above. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present disclosure within the scope of the disclosure.

[0228] This application is based upon and claims the benefit of priority from UK patent application No. 2401290.8, filed on January 31, 2024, the disclosure of which is incorporated herein in its entirety by reference.

[0229] The program can be stored and provided to the computer device using any type of non-transitory computer readable media. Non-transitory computer readable media include any type of tangible storage media. Examples of non-transitory computer readable media include magnetic storage media (such as floppy disks, magnetic tapes, hard disk drives, etc.), optical magnetic storage media (e.g. magneto-optical disks), CD-ROM (Read Only Memory), CD-R, CD-R / W, and semiconductor memories (such as mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, RAM (Random Access Memory), etc.). The program may be provided to the computer device using any type of transitory computer readable media. Examples of transitory computer readable media include electric signals, optical signals, and electromagnetic waves. Transitory computer readable media can provide the program to the computer device via a wired communication line, such as electric wires and optical fibers, or a wireless communication line.

[0230] For example, the whole or part of the example embodiments disclosed above can be described as, but not limited to, the following supplementary notes. (Supplementary note 1) 　　A method performed by a mobile terminal, the method comprising: 　　receiving, from an access network node, information indicating at least one configuration of adaptation for a channel used during cell discontinuous reception (DRX) / discontinuous transmission (DTX) inactive duration regarding the access network node; and 　　receiving, from the access network node, downlink control information indicating which of the at least one configuration should be used. (Supplementary note 2) 　　The method according to Supplementary note 1, further comprising: 　　receiving, from the access network node, information indicating configuration of cell DTX / DRX active and / or inactive duration, and wherein 　　the configuration of adaptation for the channel is configured so that occasions for the channel overlap cell DTX active duration. (Supplementary note 3) 　　The method according to Supplementary note 2, wherein 　　the information indicating configuration of the cell DTX / DRX active and / or inactive duration is transmitted via system information, and 　　the information indicating configuration of the cell DTX / DRX active and / or inactive duration is applied to mobile terminals in Radio Resource Control (RRC) idle or inactive state. (Supplementary note 4) 　　The method according to any one of Supplementary notes 1 to 3, wherein 　　the configuration of adaptation for the channel is configured so that occasions for the channel are muted or masked. (Supplementary note 5) 　　The method according to any one of Supplementary notes 1 to 4, wherein 　　the downlink control information indicates a level or type of the adaptation for the channel. (Supplementary note 6) 　　The method according to any one of Supplementary notes 1 to 5, wherein 　　the configuration of adaptation for the channel includes configuration of parameters x and y which satisfy an equation: 　　where nfindicates a system frame number, the parameters x and y indicate resources or occasions for the channel. (Supplementary note 7) 　　The method according to any one of Supplementary notes 1 to 6, wherein 　　the configuration of adaptation for the channel is configured so that occasions for the channel in a cell DTX / DRX inactive duration are delayed or skipped until an occasion in the most recent cell DTX / DRX activation duration. (Supplementary note 8) 　　The method according to any one of Supplementary notes 1 to 7, wherein 　　the configuration of adaptation for the channel is configured so that occasions for the channel in a cell DTX / DRX inactive duration are delayed or skipped until an occasion corresponding to a position determined based on an identifier of the mobile terminal. (Supplementary note 9) 　　The method according to any one of Supplementary notes 1 to 8, wherein 　　the channel is a paging channel, 　　the configuration of adaptation for the paging channel is configured by adjusting a number of Paging Frames or a number of Paging Occasions used by the mobile terminal to calculate Paging Frame or Paging Occasion, based on a number of occasions included in the cell DTX / DRX active duration. (Supplementary note 10) 　　The method according to any one of Supplementary notes 1 to 8, wherein 　　the occasion includes: 　　　　a paging occasion, 　　　　a random access channel occasion, 　　　　a synchronized signal / physical channel (PBCH) block (SSB) transmission occasion, 　　　　a tracking reference signal (TRS) transmission occasion, or 　　　　downlink / uplink common channel transmission occasion. (Supplementary note 11) 　　The method according to any one of Supplementary notes 1 to 10, further comprising: 　　receiving, from the access network node, a discovery reference signal in a case where no synchronized signal / physical broadcast channel (PBCH) block (SSB) is received due to the configuration of adaptation for the channel, in the cell DTX / DRX inactive duration. (Supplementary note 12) 　　The method according to any one of Supplementary notes 1 to 11, further comprising: 　　transmitting, to the access network node, capability information indicating the mobile terminal supports the configuration of adaptation for the mobile terminal. (Supplementary note 13) 　　The method according to any one of Supplementary notes 1 to 12, further comprising: 　　cancelling the cell DTX / DRX inactive duration in a case where the mobile terminal receives data related to high priority services or large volume data burst. (Supplementary note 14) 　　The method according to Supplementary note 13, further comprising: 　　receiving, from the access network node, information indicating that the cell DTX / DRX inactive duration becomes active temporarily, and wherein 　　the cancelling is performed upon receiving the information indicating that the cell DTX / DRX inactive duration becomes active temporarily. (Supplementary note 15) 　　The method according to any one of Supplementary notes 1 to 14, further comprising: 　　receiving, from the access network node, paging early indication indicating that a paging signal is present in a paging occasion during a next DTX / DRX active duration; and 　　waking up at which the DTX / DRX active duration including the paging occasion. (Supplementary note 16) 　　The method according to any one of Supplementary notes 1 to 15, further comprising: 　　performing cell selection / reselection using a scaling factor for threshold of measurements in a case where configuration of cell DTX / DRX active and / or inactive duration is active. (Supplementary note 17) 　　A method performed by an access network node, the method comprising: 　　transmitting, to a mobile terminal, information indicating at least one configuration of adaptation for a channel used during cell discontinuous reception (DRX) / discontinuous transmission (DTX) inactive duration regarding the access network node; and 　　transmitting, to the mobile terminal, downlink control information indicating which of the at least one configuration should be used. (Supplementary note 18) 　　A mobile terminal comprising: 　　means for receiving, from an access network node, information indicating at least one configuration of adaptation for a channel used during cell discontinuous reception (DRX) / discontinuous transmission (DTX) inactive duration regarding the access network node; and 　　means for receiving, from the access network node, downlink control information indicating which of the at least one configuration should be used. (Supplementary note 19) 　　An access network node comprising: 　　means for transmitting, to a mobile terminal, information indicating at least one configuration of adaptation for a channel used during cell discontinuous reception (DRX) / discontinuous transmission (DTX) inactive duration regarding the access network node; and 　　means for transmitting, to the mobile terminal, downlink control information indicating which of the at least one configuration should be used.

[0231] 1　　communication system 3　　UEs 5　　radio access network (RAN) node 7　　core network 9　　cells 10　　control plane functions (CPFs) 10-1　　Access and Mobility Management Functions (AMFs) 10-2　　session management function (SMF) 11　　user plane functions (UPFs) 20　　external data network 31, 51　　transceiver circuit 33, 53　　antenna 35　　user interface 37, 57　　controller 39, 59　　memory 41, 61　　operating system 43, 63　　communications control module 55　　core network interface

Claims

1. A method performed by a mobile terminal, the method comprising: 　　receiving, from an access network node, information indicating at least one configuration of adaptation for a channel used during cell discontinuous reception (DRX) / discontinuous transmission (DTX) inactive duration regarding the access network node; and 　　receiving, from the access network node, downlink control information indicating which of the at least one configuration should be used.

2. The method according to claim 1, further comprising: 　　receiving, from the access network node, information indicating configuration of cell DTX / DRX active and / or inactive duration, and wherein 　　the configuration of adaptation for the channel is configured so that occasions for the channel overlap cell DTX active duration.

3. The method according to claim 2, wherein 　　the information indicating configuration of the cell DTX / DRX active and / or inactive duration is transmitted via system information, and 　　the information indicating configuration of the cell DTX / DRX active and / or inactive duration is applied to mobile terminals in Radio Resource Control (RRC) idle or inactive state.

4. The method according to any one of claims 1 to 3, wherein 　　the configuration of adaptation for the channel is configured so that occasions for the channel are muted or masked.

5. The method according to any one of claims 1 to 4, wherein 　　the downlink control information indicates a level or type of the adaptation for the channel.

6. The method according to any one of claims 1 to 5, wherein 　　the configuration of adaptation for the channel includes configuration of parameters x and y which satisfy an equation: 　　where nfindicates a system frame number, the parameters x and y indicate resources or occasions for the channel.

7. The method according to any one of claims 1 to 6, wherein 　　the configuration of adaptation for the channel is configured so that occasions for the channel in a cell DTX / DRX inactive duration are delayed or skipped until an occasion in the most recent cell DTX / DRX activation duration.

8. The method according to any one of claims 1 to 7, wherein 　　the configuration of adaptation for the channel is configured so that occasions for the channel in a cell DTX / DRX inactive duration are delayed or skipped until an occasion corresponding to a position determined based on an identifier of the mobile terminal.

9. The method according to any one of claims 1 to 8, wherein 　　the channel is a paging channel, 　　the configuration of adaptation for the paging channel is configured by adjusting a number of Paging Frames or a number of Paging Occasions used by the mobile terminal to calculate Paging Frame or Paging Occasion, based on a number of occasions included in the cell DTX / DRX active duration.

10. The method according to any one of claims 1 to 8, wherein 　　the occasion includes: 　　　　a paging occasion, 　　　　a random access channel occasion, 　　　　a synchronized signal / physical channel (PBCH) block (SSB) transmission occasion, 　　　　a tracking reference signal (TRS) transmission occasion, or 　　　　downlink / uplink common channel transmission occasion.

11. The method according to any one of claims 1 to 10, further comprising: 　　receiving, from the access network node, a discovery reference signal in a case where no synchronized signal / physical broadcast channel (PBCH) block (SSB) is received due to the configuration of adaptation for the channel, in the cell DTX / DRX inactive duration.

12. The method according to any one of claims 1 to 11, further comprising: 　　transmitting, to the access network node, capability information indicating the mobile terminal supports the configuration of adaptation for the mobile terminal.

13. The method according to any one of claims 1 to 12, further comprising: 　　cancelling the cell DTX / DRX inactive duration in a case where the mobile terminal receives data related to high priority services or large volume data burst.

14. The method according to claim 13, further comprising: 　　receiving, from the access network node, information indicating that the cell DTX / DRX inactive duration becomes active temporarily, and wherein 　　the cancelling is performed upon receiving the information indicating that the cell DTX / DRX inactive duration becomes active temporarily.

15. The method according to any one of claims 1 to 14, further comprising: 　　receiving, from the access network node, paging early indication indicating that a paging signal is present in a paging occasion during a next DTX / DRX active duration; and 　　waking up at which the DTX / DRX active duration including the paging occasion.

16. The method according to any one of claims 1 to 15, further comprising: 　　performing cell selection / reselection using a scaling factor for threshold of measurements in a case where configuration of cell DTX / DRX active and / or inactive duration is active.

17. A method performed by an access network node, the method comprising: 　　transmitting, to a mobile terminal, information indicating at least one configuration of adaptation for a channel used during cell discontinuous reception (DRX) / discontinuous transmission (DTX) inactive duration regarding the access network node; and 　　transmitting, to the mobile terminal, downlink control information indicating which of the at least one configuration should be used.

18. A mobile terminal comprising: 　　means for receiving, from an access network node, information indicating at least one configuration of adaptation for a channel used during cell discontinuous reception (DRX) / discontinuous transmission (DTX) inactive duration regarding the access network node; and 　　means for receiving, from the access network node, downlink control information indicating which of the at least one configuration should be used.

19. An access network node comprising: 　　means for transmitting, to a mobile terminal, information indicating at least one configuration of adaptation for a channel used during cell discontinuous reception (DRX) / discontinuous transmission (DTX) inactive duration regarding the access network node; and 　　means for transmitting, to the mobile terminal, downlink control information indicating which of the at least one configuration should be used.

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