EP4710681A1

EP4710681A1 - Method, user equipment, access network node

Info

Publication number: EP4710681A1
Application number: EP24728093.6A
Authority: EP
Inventors: Pravjyot Deogun; Caroline Quanyi Liang; Maxime Grau; Hisashi Futaki
Original assignee: NEC Corp
Current assignee: NEC Corp
Priority date: 2023-05-11
Filing date: 2024-05-10
Publication date: 2026-03-18
Also published as: GB2629837A; WO2024232427A1; GB202307044D0

Abstract

The present disclosure relates to a method performed by an access network node, the method comprising: transmitting, to a user equipment, UE, an indication of at least one communication resource for use by the UE for an uplink transmission; and receiving, from the UE, the uplink transmission transmitted using the at least one communication resource; wherein the at least one communication resource overlaps in the time domain with a first period in which the access network node operates in a discontinuous reception, DRX, inactive mode; and wherein the access network node selects the at least one communication resource so that the uplink transmission at least partially overlaps with another uplink transmission in the time domain during the first period.

Description

METHOD, USER EQUIPMENT, ACCESS NETWORK NODE

　　The present disclosure relates to a communication system. The disclosure has particular but not exclusive relevance to wireless communication systems and devices thereof operating according to the 3rd Generation Partnership Project (3GPP) standards or equivalents or derivatives thereof (including LTE-Advanced, Next Generation or 5G networks, future generations, and beyond). The disclosure has particular, although not necessarily exclusive, relevance to network energy saving (NES) in 'New Radio' systems (also referred to as 'Next Generation' systems), and similar systems.

　　Recent developments of the 3GPP standards are referred to as the Long-Term Evolution (LTE) of Evolved Packet Core (EPC) network and Evolved UMTS Terrestrial Radio Access Network (E-UTRAN), also commonly referred as '4G'. In addition, the term '5G' and 'new radio' (NR) 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 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.

　　Under the 3GPP standards, a NodeB (or an eNB in LTE, 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 equipment or 'UE') connect to a core network and communicate with other communication devices or remote servers. For simplicity, the present application will use the term RAN node, base station, or access network node to refer to any such access nodes.

　　There is a need for improved wireless communication networks having improved energy efficiency (sometimes referred to as using Network Energy Saving, NES, techniques). 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. For example, the energy consumption of base stations and other similar access network nodes represents a major operational expenditure for network operators, in addition to presenting concerns with respect to the environmental impacts of operating communication systems.

　　One method of achieving a more efficient communication network is to reduce the energy requirements of the radio access network part of the system. Much of the energy consumption in modern networks is associated with the radio access network and, in particular, the Active Antenna Unit (AAU). The energy consumption of the radio access network includes a dynamic part that is associated with data transmission and reception, and a static part that is associated with operations of the radio access devices that are performed even when there is no ongoing data transmission or reception. Energy saving modes may be configured for one or more devices in the system (e.g. an access network node, or the UE). For example, a UE or access network node may be configured to operate in an energy saving mode (which may also be referred to as a sleep mode) in which the device performs a reduced number of transmissions, or in which the device is configured not to attempt to transmit or 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).

　　Many proposals have been made for UE DTX/DRX operation, and attention is turning now to such discontinuous operation of one or more base station cells - which is referred to as "cell DTX/DRX". With cell DTX/DRX, the cell (RAN node) stops transmitting and receiving during certain periods of time. Improved methods for cell DTX/DRX are needed. For example, more reliable communication methods in which the UE is able to reliably transmit high priority transmissions (e.g. ultra reliable and low latency communications, URLLC) to the base station even when the base station is using DTX/DRX are needed.

NPL 1: 'NGMN 5G White Paper' V1.0 by the Next Generation Mobile Networks (NGMN) Alliance, which document is available from https://www.ngmn.org/5g-white-paper.html.
NPL 2: TS38.331 V17.4.0
NPL 3: TS38.321 V17.4.0
NPL 4: TS38.212 V17.5.0

　　More generally, there is a need for more efficient and reliable methods and apparatus for increasing the energy efficiency of wireless communication systems. Improved apparatus and methods for network energy saving whilst providing reliable and efficient communication are therefore needed.

　　In one aspect the disclosure provides a method performed by an access network node, the method comprising: transmitting, to a user equipment, UE, an indication of at least one communication resource for use by the UE for an uplink transmission; and receiving, from the UE, the uplink transmission transmitted using the at least one communication resource; wherein the at least one communication resource overlaps in the time domain with a first period in which the access network node operates in a discontinuous reception, DRX, inactive mode; and wherein the access network node selects the at least one communication resource so that the uplink transmission at least partially overlaps with another uplink transmission in the time domain during the first period.

　　The uplink transmission may be a physical uplink control channel, PUCCH, transmission, and the at least one communication resource may comprise time and frequency resources for the PUCCH transmission.
The uplink transmission may comprise uplink control information, UCI, transmitted using the PUCCH.

　　The uplink transmission may comprise a scheduling request, SR, channel state information, CSI, report, or hybrid automatic repeat request, HARQ, feedback.
The uplink transmission may comprise a SR or CSI, and the SR or CSI may be associated with an uplink transmission for a beam management procedure, a radio link failure procedure, a beam failure procedure, or a handover procedure.
　　The indication of the at least one communication resource may comprise an indication of a periodicity for the uplink transmission.
　　The access network node may operate in a DRX active mode during a second period, different from the first period, and the indication of at least one communication resource may comprise an indication of a difference between the at least one communication resource and a communication resource used for the uplink transmission during the second period.
　　The indication of at least one communication resource may comprise an indication of a difference in periodicity or time offset for the uplink transmission.
　　The method may further comprise transmitting, to the UE, an indication that a configuration for an uplink transmission for use in the second period is to be disabled during the first period.
　　The uplink transmission may comprise HARQ feedback for a downlink transmission; and the indication of at least one communication resource for use by the UE for the uplink transmission may comprise an indication of a time period between reception of the downlink transmission at the UE and transmission of the HARQ feedback.

　　The time period between reception of the downlink transmission at the UE and transmission of the HARQ feedback may be larger than 15 slots.
　　The time period between reception of the downlink transmission at the UE and transmission of the HARQ feedback during the first period may be larger than a time period between reception of the downlink transmission at the UE and transmission of the HARQ feedback that is supported when the access network node is operating in a DRX active mode.
　　The another uplink transmission may comprise uplink control information transmitted by another UE.
　　The another uplink transmission may be transmitted by the UE.
　　The uplink transmission may comprise HARQ feedback associated with a first downlink transmission, and the another uplink transmission may comprise HARQ feedback that is associated with a second downlink transmission.
　　The method may comprise transmitting, to the UE, an indication of one or more PUCCH configurations for use by the UE for uplink transmissions in the first period but not in the second period.

　　The method may comprise transmitting, to the UE, an indication of a configuration for transmission of a physical uplink shared channel, PUSCH, during the first period that is different from a configuration for transmission of the PUSCH during the second period.
　　The method may comprise transmitting, to the UE, information indicating whether transmission of a scheduling request is allowed during the first period.
　　The information indicating whether transmission of a scheduling request is allowed during the first period may indicate whether transmission of the scheduling request is allowed during the first period per scheduling request or per logical channel.

　　In another aspect the disclosure provides a method performed by a user equipment, UE, the method comprising: receiving, from an access network node, an indication of at least one communication resource for use by the UE for an uplink transmission; and transmitting, to the access network node, the uplink transmission using the at least one communication resource; wherein the at least one communication resource overlaps in the time domain with a first period in which the access network node operates in a discontinuous reception, DRX, inactive mode; and wherein the at least one communication resource is selected so that the uplink transmission at least partially overlaps with another uplink transmission in the time domain during the first period.
　　The uplink transmission may be a PUCCH transmission, and the at least one communication resource may comprise time and frequency resources for the PUCCH transmission.
　　The uplink transmission may comprise uplink control information, UCI, transmitted using the PUCCH.
　　The uplink transmission may comprise a scheduling request, SR, channel state information, CSI, report, or hybrid automatic repeat request, HARQ, feedback.
　　The uplink transmission may comprise a SR or CSI, and the SR or CSI may be associated with an uplink transmission for a beam management procedure, a radio link failure procedure, a beam failure procedure, or a handover procedure.

　　The indication of the at least one communication resource may comprise an indication of a periodicity for the uplink transmission.
　　The access network node may operate in a DRX active mode during a second period, different from the first period, and the indication of at least one communication resource may comprise an indication of a difference between the at least one communication resource and a communication resource used for the uplink transmission during the second period.
　　The indication of at least one communication resource may comprise an indication of a difference in periodicity or time offset for the uplink transmission.
　　The method may further comprise receiving, from the access network node, an indication that a configuration for an uplink transmission for use in the second period is to be disabled during the first period.
　　The uplink transmission may comprise HARQ feedback for a downlink transmission; and the indication of at least one communication resource for use by the UE for the uplink transmission may comprise an indication of a time period between reception of the downlink transmission at the UE and transmission of the HARQ feedback.
　　The time period between reception of the downlink transmission at the UE and transmission of the HARQ feedback may be larger than 15 slots.
　　The time period between reception of the downlink transmission at the UE and transmission of the HARQ feedback during the first period may be larger than a time period between reception of the downlink transmission at the UE and transmission of the HARQ feedback that is supported when the access network node is operating in a DRX active mode.
　　The another uplink transmission may comprise uplink control information transmitted by another UE.

　　The another uplink transmission may be transmitted by the UE.
　　The uplink transmission may comprise HARQ feedback associated with a first downlink transmission, and the another uplink transmission may comprise HARQ feedback that is associated with a second downlink transmission.

　　The method may comprise receiving, from the access network node, an indication of one or PUCCH configurations for use by the UE for uplink transmissions in the first period but not in the second period.

　　The method may comprise receiving, from the access network node, an indication of a configuration for transmission of a physical uplink shared channel, PUSCH, during the first period that is different from a configuration for transmission of the PUSCH during the second period.

　　The method may comprise receiving, from the access network node, information indicating whether transmission of a scheduling request is allowed during the first period.
The information indicating whether transmission of a scheduling request is allowed during the first period may indicate whether transmission of the scheduling request is allowed during the first period per scheduling request or per logical channel.

　　The method may further comprise: transmitting a scheduling request to the access network node when the access network node is operating in a discontinuous transmission, DTX, inactive mode; and monitoring for transmission of downlink control information corresponding to the scheduling request during a period assigned for operation of the access network node in the DTX inactive mode.

　　In another aspect the disclosure provides a method performed by a user equipment, UE, the method comprising: determining to initiate a random access procedure comprising transmission on a physical random access channel, PRACH, to an access network node; determining whether transmission on the PRACH is allowed during a first period in which the access network node operates in a discontinuous reception, DRX, inactive mode; if it is determined that transmission on the PRACH is not allowed during the first period, then delaying transmission of the PRACH until the access network node is operating in a DRX active mode; and if it is determined that transmission on the PRACH is allowed during the first period, then transmitting the PRACH to the access network node during the first period.

　　The determination to initiate the random access procedure may be made before the first period, when the access network node is operating in a DRX active mode, but a first time occasion available for transmission of the PRACH overlaps with the first period.
The determination to initiate the random access procedure may be made during the first period.
In another aspect the disclosure provides a method performed by an access network node, the method comprising: receiving a scheduling request from a UE during a first period for operation of the access network node in a discontinuous reception, DRX, inactive mode using a first DRX configuration; and determining, based on the scheduling request, to use a second DRX configuration that defines a set of second periods in which the access network node is to operate in a DRX inactive mode and a set of third periods in which the access network node is to operate in a DRX active mode; wherein the second periods and the third periods are shorter than the first period.
The determination to use the second DRX configuration may be based on an uplink transmission priority associated with the scheduling request.

　　The method may further comprise configuring a set of configured grant resources for the UE to overlap in the time domain with the third periods.
The set of second periods and the set of third periods may be arranged within the first period.
The method may further comprise transmitting an indication to the UE that an uplink transmission corresponding to the scheduling request is to be transmitted during the first period.
The method may further comprise transmitting an indication to the UE that the access network node is to use the second DRX configuration.

　　In another aspect the disclosure provides method performed by a user equipment, UE, the method comprising: transmitting a scheduling request to an access network node during a first period in which the access network node is operating in discontinuous reception, DRX, inactive mode using a first DRX configuration; receiving, from the access network node, an indication that an uplink transmission corresponding to the scheduling request is to be transmitted during the first period; and transmitting the uplink transmission to the access network node during the first period.
In another aspect the disclosure provides an access network node comprising: means for transmitting, to a user equipment, UE, an indication of at least one communication resource for use by the UE for an uplink transmission; and means for receiving, from the UE, the uplink transmission transmitted using the at least one communication resource; wherein the at least one communication resource overlaps in the time domain with a first period in which the access network node operates in a discontinuous reception, DRX, inactive mode; and wherein the access network node is configured to select the at least one communication resource so that the uplink transmission at least partially overlaps with another uplink transmission in the time domain during the first period.

　　In another aspect the disclosure provides a user equipment, UE, comprising: means for receiving, from an access network node, an indication of at least one communication resource for use by the UE for an uplink transmission; and means for transmitting, to the access network node, the uplink transmission using the at least one communication resource; wherein the at least one communication resource overlaps in the time domain with a first period in which the access network node operates in a discontinuous reception, DRX, inactive mode; and wherein the at least one communication resource is selected so that the uplink transmission at least partially overlaps with another uplink transmission in the time domain during the first period.

　　In another aspect the disclosure provides a user equipment, UE, comprising: means for determining to initiate a random access procedure comprising transmission on a physical random access channel, PRACH, to an access network node; and means for determining whether transmission on the PRACH is allowed during a first period in which the access network node operates in a discontinuous reception, DRX, inactive mode; wherein the UE is configured for: if it is determined that transmission on the PRACH is not allowed during the first period, delaying transmission of the PRACH until the access network node is operating in a DRX active mode; and if it is determined that transmission on the PRACH is allowed during the first period, transmitting the PRACH to the access network node during the first period.

　　In another aspect the disclosure provides an access network node comprising: means for receiving a scheduling request from a UE during a first period for operation of the access network node in a discontinuous reception, DRX, inactive mode using a first DRX configuration; and means for determining, based on the scheduling request, to use a second DRX configuration that defines a set of second periods in which the access network node is to operate in a DRX inactive mode and a set of third periods in which the access network node is to operate in a DRX active mode; wherein the second periods and the third periods are shorter than the first period.

　　In another aspect the disclosure provides a user equipment, UE, comprising: means for transmitting a scheduling request to an access network node during a first period in which the access network node is operating in discontinuous reception, DRX, inactive mode using a first DRX configuration; means for receiving, from the access network node, an indication that an uplink transmission corresponding to the scheduling request is to be transmitted during the first period; and means for transmitting the uplink transmission to the access network node during the first period.

　　Example embodiments of the disclosure will now be described, by way of example, with reference to the accompanying drawings in which:
Fig. 1 schematically illustrates a mobile ('cellular' or 'wireless') telecommunication system; Fig. 2 illustrates a typical frame structure that may be used in the telecommunication system of Fig. 1; Fig. 3 is a schematic block diagram illustrating the main components of a DU that may be used as part of the RAN node 5 for the communication system 1 shown in Fig. 1; Fig. 4 is a schematic block diagram illustrating the main components of a CU that may be used as part of the RAN node 5 for the communication system 1 shown in Fig. 1; Fig. 5 shows a mobility procedure in which handover occurs from a source (R)AN node to a target (R)AN node; Fig. 6 shows a random access (RA) procedure that may be performed in the system of Fig. 1; Fig. 7 shows an example in which HARQ feedback is transmitted by a UE; Fig. 8 shows an example in which downlink control information related to HARQ feedback is transmitted from a (R)AN node to a UE; Fig. 9 shows an example of a DRX cycle or pattern; Fig. 10 shows an example in which PUCCH resources are scheduled during a period in which the base station is in the DRX inactive state; Fig. 11 shows a further example in which PUCCH resources are scheduled during a period in which the base station is in the DRX inactive state; Fig. 12 shows an example in which the number of time occasions in which the base station is to receive uplink transmissions during the DRX inactive period is beneficially reduced; Fig. 13 shows an example in which transmission of HARQ feedback is delayed within the DRX inactive period of the base station; Fig. 14 shows an example in which communication resources for transmission of PUCCH are different between the DRX active period and the DRX inactive period; Fig. 15 shows an example in which RACH transmission is not allowed during the DRX inactive period of the base station; Fig. 16 shows an example in which RACH transmission is allowed during the DRX inactive period of the base station; Fig. 17 shows an example in which RACH is triggered due to SR during a DRX active period, but the first available PRACH occasion is within the DRX inactive period; Fig. 18 shows an example in which the base station may have a long cell DRX configuration or a short cell DRX configuration; Fig. 19 is a schematic block diagram illustrating the main components of a UE for the communication system of Fig. 1; Fig. 20 is a schematic block diagram illustrating the main components of a base station for the communication system of Fig. 1; and Fig. 21 is a schematic block diagram illustrating the main components of a core network node or function for the communication system of Fig. 1.

　　Overview
　　An exemplary communication system will now be described in general terms, by way of example only, with reference to Figs. 1 and 2.
　　Fig. 1 schematically illustrates a mobile ('cellular' or 'wireless') communication system 1 to which example embodiments of the present disclosure are applicable.

　　In the communication system 1, user equipment (UEs) 3-1, 3-2, 3-3 (e.g. mobile telephones and/or other mobile devices) can communicate with each other via a radio access network (RAN) 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 base station 5 is typically routed through a core network 7 (e.g. a 5G/6G core network or evolved packet core network (EPC)).

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

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

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

　　The core network 7 includes a number of logical nodes (or 'functions') for supporting communication in the 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, one or more network node entities for session management (e.g. Session Management Functions (SMFs)) 10-2 and a number of other functions 10-n.

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

　　One or more UPFs 11 are connected to an external data network (e.g. an IP network such as the internet) via an appropriate interface (or 'reference point') such as a N6 reference point for communication of the user data.
　　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 SMF 10-2 provides session management functionality (that formed part of MME functionality in LTE) and additionally combines some control plane functions (provided by the serving gateway and packet data network gateway in LTE). The SMF 10-2 also allocates IP addresses to each UE 3.

　　The base station 5 of the communication system 1 is configured to operate at least one cell 9 on an associated TDD carrier that operates in unpaired spectrum. It will be appreciated that the base station 5 may also operate at least one cell 9 on an associated FDD carrier that operates in paired spectrum.

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

　　The physical channels may include, for example, a physical downlink shared channel (PDSCH), a physical broadcast channel (PBCH), and a physical downlink control channel (PDCCH). The PDSCH carries data sharing the PDSCH's capacity on a time and frequency basis. The PDSCH can carry a variety of items of data including, for example, user data, UE-specific higher layer control messages mapped down from higher channels, system information blocks (SIBs), and paging. The PDCCH carries downlink control information (DCI) for supporting a number of functions including, for example, scheduling the downlink transmissions on the PDSCH and also the uplink 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. The UE 3 may receive a Synchronization Signal Block (SSB), and the UE 3 may assume that reception occasions of a PBCH, primary synchronization signal (PSS) and secondary synchronization signal (SSS) are in consecutive symbols and form a SS/PBCH block. The base station 5 may transmit a number of synchronization signal (SS) blocks corresponding to different DL beams. The total number of SS blocks may be confined, for example, within a 5 ms duration as an SS burst. The periodicity of the SSB transmissions may be indicated to the UE using any suitable signalling (e.g. per serving cell using ssb-periodicityServingCell). The periodicity value for the SSB may be, for example, greater than or equal to 20 ms. For initial cell selection, the UE 3 may be configured to assume that an SS burst occurs with a periodicity of 2 frames. The UE 3 may also be provided with an indication of which SSBs within a 5 ms duration are transmitted (e.g. using ssb-PositionsInBurst).

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

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

　　When the UE 3 initially establishes a radio resource control (RRC) connection with a base station 5 via a cell 9 it registers with an appropriate core network node (e.g., AMF, MME). The UE 3 is in the so-called RRC connected state and an associated UE context is maintained by the network. When the UE 3 is in the so-called RRC idle state, or is in the RRC inactive state, it selects an appropriate cell for camping so that the network is aware of the approximate location of the UE 3 (although not necessarily on a cell level).

　　The base station 5 may be a base station 5 that is split between one or more distributed units (DUs) 50 and a central unit (CU) 60, with a CU 60 typically performing higher level functions and communication with the next generation core, and with the DU 50 performing lower level functions and communication over an air interface with UEs 3 in the vicinity (i.e. in a cell operated by the base station 5). This type of base station 5 may be referred to as a 'distributed' base station 5 or gNB 5. A distributed gNB 5 includes the following functional units:
gNB Central Unit (gNB-CU): a logical node hosting Radio Resource Control (RRC), Service Data Adaptation Protocol (SDAP) and Packet Data Convergence Protocol (PDCP) layers of the gNB (or RRC and PDCP layers of an en-gNB) that controls the operation of one or more gNB-DUs. The gNB-CU terminates the so-called F1 interface connected with the gNB-DU.
gNB Distributed Unit (gNB-DU): a logical node hosting Radio Link Control (RLC), Medium Access Control (MAC) and Physical (PHY) layers of the gNB or en-gNB, and its operation is partly controlled by the gNB-CU. One gNB-DU supports one or multiple cells. One cell is supported by only one gNB-DU. The gNB-DU terminates the F1 interface connected with the gNB-CU.
gNB-CU-Control Plane (gNB-CU-CP): a logical node hosting the RRC and the control plane part of the PDCP protocol of the gNB-CU for an en-gNB or a gNB. The gNB-CU-CP terminates the so-called E1 interface connected with the gNB-CU-UP and the F1-C (F1 control plane) interface connected with the gNB-DU.
gNB-CU-User Plane (gNB-CU-UP): a logical node hosting the user plane part of the PDCP protocol of the gNB-CU for an en-gNB, and the user plane part of the PDCP protocol and the SDAP protocol of the gNB-CU for a gNB. The gNB-CU-UP terminates the E1 interface connected with the gNB-CU-CP and the F1-U (F1 user plane) interface connected with the gNB-DU.

　　It will be appreciated that when a distributed base station or a similar control plane - user plane (CP-UP) split is employed, the control-plane and user-plane entities may each include an associated transceiver circuit, antenna, network interface, controller, memory, operating system, and communications control module. When the base station 5 comprises a distributed base station, the network interface also includes an E1 interface and an F1 interface (F1-C for the control plane and F1-U for the user plane) to communicate signals between respective functions of the distributed base station.

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

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

Table 1 - 5G Numerology

　　RAN node
DU
　　Fig. 3 is a schematic block diagram illustrating the main components of a DU 50 that may be used as part of the RAN node 5 for the communication system 1 shown in Fig. 1. As shown, the DU 50 has a transceiver circuit 451 for: transmitting signals to, and for receiving signals from, the communication devices (such as UEs 3) via the radio unit (RU) and the associated DU-RU interface 453; and for transmitting signals to, and for receiving signals from, the CU 60 of the RAN node 5 via a CU interface 454 (e.g. comprising an F1 interface which may be split into an F1-U and an F1-C interface for user plane and control plane signalling respectively).
The DU 50 has a controller 457 for controlling the operation of the DU 50. The controller 457 is associated with a memory 459. Software may be pre-installed in the memory 459 and/or may be downloaded via the communications network 1 or from a removable data storage device (RMD) for example. The controller 457 is configured to control the overall operation of the DU 50 by, in this example, program instructions or software instructions stored within memory 459.

　　As shown, these software instructions include, among other things, an operating system 461, a communications control module 463, an F1 module 465, a DU-RU module 468, a DU management module 472, a UE profile management module 473 and a mobility module 475.

　　The communications control module 463 is operable to control the communication between the DU 50 and one or more RUs (and hence between the DU 50 and the UE 3), and between the DU 50 and the CU 60. The communications control module 463 is configured for the overall control of the reception of signals corresponding to uplink communications from the UE 3 and for handling the transmission of downlink communications to the UE 3.

　　The F1 module 465 is responsible for the appropriate processing of signals received from, or transmitted to, the CU 60 via one or more CU (e.g. F1) interfaces 454. These signals may be separated into: user plane signals received from, or transmitted to, the CU-UP part of the CU 60 via the F1-U interface; and control plane signals received from, or transmitted to, the CU-CP part of the CU 60 via the F1-C interface.

　　The DU-RU module 468 is responsible for the appropriate processing of signals received from, or transmitted to, the RU via one or more RU (e.g. DU-RU) interfaces 453.
The DU management module 472 is responsible for managing the overall operation of the DU 50 and the overall performance of the tasks required of the DU 50. These tasks include, among other things, the generation and transmission of appropriate messages using appropriate signalling application protocols, depending on the functional split between the RU, DU 50 and CU 60, such as interpretation of received MAC signalling and the generation of MAC signalling for transmission. The DU management module 472 may control the overall operation of the DU 50 in accordance with any of the methods describe below, where appropriate.

　　The UE profile management module 473 is responsible for carrying out functions related to the UE profile including (where applicable): the reception and storage of the UE profile or related assistance/preference information from the UE 3 or from elsewhere in the network; the determination (where applicable) of appropriate mobility specific configurations, based on the UE profile / assistance information / preference information, for implementation at the UE 3 and/or RAN node 5; and/or the provision of configuration information (where applicable) for configuring the UE appropriately with mobility based configurations. The UE profile management module 473 may also store, for example, previous mobility information for a UE 3 (e.g. previous movements of the UE 3 between different communication cells of the network). It will be appreciated that, depending on implementation, the DU 50 may not implement at least some of these features. The mobility module 475 is responsible for controlling mobility procedures for one or more UEs 3. For example, the mobility module 475 may be configured to perform one or more measurements for UE 3 mobility, or to select a candidate cell for handover.

CU
　　Fig. 4 is a schematic block diagram illustrating the main components of the CU 60 of the RAN node 5 for the communication system 1 shown in Fig. 1. As shown, the CU 60 has a transceiver circuit 551 for: transmitting signals to, and for receiving signals from, the DU 50 via one or more DU interfaces 554 (e.g. comprising an F1 interface which may be split into an F1-U and an F1-C interface for user plane and control plane signalling respectively); and for transmitting signals to, and for receiving signals from, the functions of the core network 7 via one or more core network interfaces 555 (e.g. comprising the N2 and N3 interfaces or the like).

　　The CU 60 has a controller 557 to control the operation of the CU 60. The controller 557 is associated with a memory 559. Software may be pre-installed in the memory 559 and/or may be downloaded via the communications network 1 or from a removable data storage device (RMD) for example. The controller 557 is configured to control the overall operation of the CU 60 by, in this example, program instructions or software instructions stored within memory 559.

　　As shown, these software instructions include, among other things, an operating system 561, a communications control module 563, an F1 module 565, an E1 module 566, an N2 module 568, an N3 module 569, a CU-UP management module 571, a CU-CP management module 572, a UE profile management module 573, and a mobility module 575. The functions of the mobility module 575 are the same as described above with reference to Fig. 3.

　　The communications control module 563 is operable to control the communication between the CU 60 and one or more DUs 50 (and hence between the CU 60 and the UE 3), and between the CU 60 and the core network 7. The communications control module 563 is configured for the overall control of the reception of signals corresponding to uplink communications from the UE 3 and for controlling the transmission of downlink communications.

　　The F1 module 565 is responsible for the appropriate processing of signals received from, or transmitted to, the DU 50 via one or more DU (e.g. F1) interfaces 554. These signals include: user plane signals received at, or transmitted by, the CU-UP part of the CU 60 via the F1-U interface; and control plane signals received at, or transmitted by, the CU-CP part of the CU 60 via the F1-C interface.

　　The E1 module 566 is responsible for the appropriate processing of signals transmitted between the CU-UP part of the CU 60 and the CU-CP part of the CU 60 via the corresponding internal CU interface (e.g. E1).

　　The N2 module 568 is responsible for the appropriate processing of signals received from, or transmitted to, the AMF 10-1 via one or more corresponding core network interfaces (e.g. N2) 555.
　　The N3 module 569 is responsible for the appropriate processing of signals received from, or transmitted to, the core network user plane function(s) via one or more corresponding core network interfaces (e.g. N3) 555.

　　The CU-UP management module 571 is responsible for managing the overall operation of the CU-UP part of the CU 60 and the overall performance of the tasks required of the CU-UP.
The CU-CP management module 572 is responsible for managing the overall operation of the CU-CP part of the CU 60 and the overall performance of the tasks required of the CU-CP. These tasks include, among other things, the generation and transmission of appropriate messages using appropriate signalling application protocols, depending on the functional split between the RU, DU 50 and CU 60, such as interpretation of received RRC signalling and the generation of RRC signalling for transmission.

　　The UE profile management module 573 is responsible for carrying out functions related to the UE (mobility) profile including (where applicable): the reception and storage of the UE profile or related assistance/preference information from the UE 3 or from elsewhere in the network; the determination of appropriate mobility specific configurations, based on the UE profile / assistance information / preference information, for implementation at the UE 3 and/or RAN node 5; and/or the provision of configuration information for configuring the UE appropriately with mobility based configurations. The UE profile management module 573 may also store previous mobility information for a UE 3 (e.g. previous movements of the UE 3 between different communication cells of the network). It will be appreciated that, depending on implementation, the CU 60 may not implement at least some of these features.

System information and SIB
It will be appreciated that transmissions in a cell 9 of a base station 5 may include one or more broadcast transmissions, one or more unicast transmissions for reception by a UE 3, and/or one or more multicast transmissions for reception by a group of UEs 3. System information (SI) transmitted in a cell may include 'minimum SI' (MSI) and 'other SI' (OSI). The OSI may be broadcast on-demand, for example using a downlink shared channel (DL-SCH). The OSI may be broadcast upon request from a UE 3 that is in a radio resource control (RRC) idle or RRC inactive state. The OSI may also be requested by a UE 3 that is in the RRC connected state, for example via one or more dedicated RRC transmissions.

　　The SI may include information for enabling (e.g. configuring) the UE 3 to complete a cell selection, may include information for enabling the UE 3 to complete a cell reselection procedure, or for enabling the UE 3 to receive one or more paging messages transmitted in a cell. SI may be broadcast using a Master Information Block (MIB) and one or more System Information Blocks (SIB).

　　The MSI comprises the MIB and system information block 1 (SIB1). The MIB includes information for use by the UE 3 to receive SIB1, for example a subcarrier spacing for SIB1. The MIB provides information corresponding to a Control Resource Set (CORESET) and Search Space. SIB1 may be referred to as 'remaining MSI' (RMSI). SIB1 may be transmitted in a dedicated RRC message, and other SIB (e.g. SIB2 to SIB9) may be transmitting using one or more other suitable RRC transmissions (e.g. another dedicated RRC message). The MIB and SIB1 may provide the UE 3 with an indication of scheduling information for receiving and decoding the other SIB, such as SIB2 to SIB9, and may provide information for use by the UE 3 to receive one or more paging messages. The OSI may comprise, for example, SIB2 to SIB9 transmitted using a DL-SCH in SI messages. A mapping of SIB2 to SIB9 to corresponding SI messages may be provided to the UE 3 by the base station 5. MIB and SIB1 to SIB9 are described in more detail, for example, in 3GPP TS 38.331. SIB2 provides information for intra-frequency, inter-frequency and inter-system cell reselection. SIB3 provides cell-specific information for intra-frequency cell reselection. SIB4 provides information for inter-frequency cell reselection. SIB5 provides information regarding inter-system cell reselection towards 4G (LTE). SIB6 and SIB7 provide information for an earthquake and tsunami warning system (ETWS). SIB8 provides information for a commercial mobile alert service (CMAS) notification, for example to provide warning text messages to the UE 3. SIB9 includes information regarding coordinated universal time (UTC), global positioning system (GPS) time (e.g. for GPS initialisation) and local time.

　　SIB may be broadcast periodically (e.g. according to a predetermined periodic pattern), or alternatively may be provided 'on-demand', for example in response to a request from a UE 3. For example, MIB may be transmitted with a periodicity of 80 ms and repetitions made within 80 ms, and SIB1 may be transmitted with a periodicity of 160 ms and a variable transmission repetition periodicity within 160 ms (e.g. 20 ms). SIB1 can be used to indicate to a UE 3 which SIB are transmitted periodically and which SIB are available on-demand in response to a request from the UE 3. A UE 3 may be configured to request on-demand SIB using message 1 (MSG1), which may be referred to as a MSG1-based on-demand SI request, or message 3 (MSG3), which may be referred to as a MSG3-based on-demand SI request.

　　A physical broadcast channel (PBCH) can be used to broadcast the MIB. The base station 5 may transmit the PBCH with synchronisation signals (SS) (e.g. primary synchronisation signal (PSS) and secondary synchronisation signal (SSS)) in a SS/PBCH Block. The SS/PBCH block comprises four orthogonal frequency-division multiplexed (OFDM) symbols that are mapped to PSS, SSS and PBCH associated with a demodulation reference signal (DM-RS). In the frequency domain, an SS/PBCH block comprises 240 contiguous subcarriers. When the UE 3 is in an RRC connected state, the base station 5 may provide the UE 3 with an indication of resources used for the SS/PBCH, for example using dedicated signalling. SIB1 may be transmitted using a physical downlink shared channel (PDSCH). The OSI may be similarly transmitted, for example, using a PDSCH. When one or more beamformed transmissions are transmitted in a cell provided by the base station 5, some of the SI (e.g. some of the SIB) may only be transmitted using particular beams, or using a particular transmission/reception point (TRP).

UE Mobility
　　Fig. 5 shows an overview of a mobility procedure that may be performed in a communication system 1 of the type illustrated in Fig. 1. In this example, a handover of a UE 3 from a source base station 5 to a target base station 5 is performed.

　　In optional step S501 the UE 3 performs a measurement. The measurement may be a measurement of a signal transmitted by the source (R)AN node 5 or a measurement of a signal transmitted by the target (R)AN node 5. The measurement may be a measurement of a signal strength, that can be used as part of a determination that the UE 3 is to be handed over from the source (R)AN node 5 to the target (R)AN node 5. In optional step S502 the UE 3 transmits a measurement report to the source (R)AN node 5 that provides an indication of the result of the measurement. The measurement report may be transmitted from the UE 3 to the source base station 5 in an RRC message. In this example the source (R)AN node 5 uses the information provided in the measurement report to determine that the UE 3 is to be handed over to the target (R)AN node 5. However, it will be appreciated that a determination that handover to the target (R)AN node 5 is to be performed may alternatively (or additionally) be based on a measurement performed at the source (R)AN node 5 or at the target (R)AN node 5. Alternatively, a determination that handover of the UE 3 is to be performed may be based on a factor other than a signal measurement, such as a level of congestion in a cell operated by the source (R)AN node 5.

　　In Step S503 the source (R)AN node 5 transmits a handover request to the target (R)AN node 5, requesting handover of the UE 3 from the source (R)AN node 5 to the target (R)AN node 5. The handover request may include an indication of, for example, an identity of the source (R)AN node 5, a cause value for the handover, an identity of the target cell, UE 3 context information (e.g. a maximum bit rate of the UE 3, or security capabilities of the UE 3), and UE history information. If the handover has been triggered by the measurement report received by the source (R)AN node 5 in step S502, then the cause value may indicate, for example, that the handover is desirable for radio reasons. Alternatively, if the handover has been triggered to reduce the load at the source (R)AN node 5, the cause value may indicate that the handover is for reducing load in the serving cell. The handover request message may also include an indication of the AMF 10-1 that is serving the UE 3.

　　In step S504, the target (R)AN node 5 transmits an acknowledgement of the handover request (which may be referred to as a "handover request acknowledgement" message). The handover request acknowledgement message includes an indication of handover configuration information for the handover that is to be forwarded to the UE 3. The handover request acknowledgement message may also include configuration information that enables the source (R)AN node 5 to begin forwarding user plane data for the UE 3 to the target (R)AN node 5.

　　The transmissions of steps S503 and S504 may be performed over an Xn interface between the source (R)AN node 5 and the target (R)AN node 5 (and therefore the handover procedure in this example may be referred to as an Xn-based handover procedure). Steps S501 to S504 may be referred to as a 'handover preparation phase'.

　　In step S505, the source (R)AN node 5 transmits the handover configuration information to the UE 3. The configuration information for the handover may be, for example, an RRC configuration transmitted in an RRC configuration message or an RRC reconfiguration message. In step S506, the UE 3 applies the received configuration for handover and transmits an indication to the target (R)AN node 5 that configuration for the handover is complete. The message transmitted in step S505 may be, for example, an RRC Reconfiguration Complete message. Steps S505 and S506 may be referred to as a 'handover execution phase'.

　　Following the handover execution phase, the UE 3 is operable to transmit uplink transmissions to the target (R)AN node 5 (e.g., uplink data) and receive downlink transmissions from the target (R)AN node 5 (e.g. downlink data).

　　It will be appreciated that mobility methods and handover procedures for the UE 3 are not restricted to the example illustrated in Fig. 5. For example, the UE 3 may be configured to perform a conditional handover (CHO) in which the UE 3 determines whether handover of the UE 3 to a candidate cell is to be performed based on one or more execution conditions. It will also be appreciated that handover may be performed in which the DU 50 changes but the CU 60 remains the same (inter-DU intra-CU handover), in which both the DU 50 and CU 60 change (inter-DU inter-CU handover), or between two cells operated by the same DU 50.

Random Access
　　Fig. 6 shows a random access (RA) procedure that may be performed in the system of Fig. 1. The RA procedure can be used, for example, for initial access by a UE 3 that is in the RRC idle mode, or for a transition from the RRC inactive mode to the RRC connected mode. The RA procedure may also be used during handover of the UE 3 from a source base station to a target base station (e.g. the handover procedure described above with reference to Fig. 5), for initial access to the target base station 5.

　　In step S601 the UE 3 transmits a random access preamble to the base station 5. In this example the UE 3 selects the random access preamble to transmit from a group of random access preambles that are shared with other UEs 3. The transmission of step S601 may be referred to as message 1 (MSG1), and is transmitted using PRACH.

　　In step S602 the base station 5 transmits a random access response to the UE 3. The transmission of step S602 may be referred to as message 2 (MSG2). The random access response indicates time and/or frequency resources (e.g. resource blocks and/or symbols) for use by the UE 3 to transmit a subsequent transmission to the base station 5. The random access response may also include further information for use by the UE 3 for communication with the base station 5, such as a timing advance (TA) value.

　　In step S603 the UE 3 transmits a transmission to the base station 5 using the indicated time and/or frequency resources. The transmission of step S603 may be referred to as message 3 (MSG3). The transmission of step S603 may be a layer 2 (L2) or layer 3 (L3) message. The transmission of step S603 may comprise, for example, an RRC setup request, an RRC resume request, an RRC reestablishment request, or an RRC reconfiguration complete message.

　　If two UEs 3 selected and transmitted the same random access preamble in step S601, and receive and decode MSG2 transmitted by the base station 5 in step S602, then the two UEs may transmit MSG3 using the same time and/or frequency resources. This situation can be referred to as 'contention' or 'collision'. In order to resolve the contention, in step S604 the base station 5 transmits a content resolution message to the UE 3. The transmission of step S604 may be referred to as message 4 (MSG4). MSG4 indicates to the UE 3 whether the MSG3 transmitted by the UE 3 in step S603 was received and successfully decoded by the base station. MSG3 transmitted in step S603 may not have been received or successfully decoded by the base station 5 if the base station 5 decoded a MSG3 transmitted by another UE 3 that is in contention with the UE 3, or if interference occurred between the MSG3 transmitted by the two UEs 3. If MSG3 transmitted by the UE 3 was not decoded by the base station 5 (which the UE 3 may determine if the UE 3 does not receive MSG4 from the base station 5), then the UE 3 returns to step S601 of the method and transmits another MSG1 to the base station 5 (e.g. after selecting a different random access preamble).

　　The procedure illustrated in Fig. 6 is an example of a contention based RA procedure in which the UE 3 selects the random access preamble from a group of preambles that could also be used by other UEs 3 (and therefore contention can occur if two of the UEs 3 select the same random access preamble). Alternatively, the base station 5 may transmit a random access preamble assignment to the UE 3 before the UE 3 transmits MSG 1 to the base station 5, in which case the RA procedure is contention free (and the contention resolution in step S604 need not be performed). The random access preamble assignment may be transmitted to the UE 3 using an RRC message or layer 1 (L1) signalling (e.g. using DCI carried by a PDCCH). In the method illustrated in Fig. 5, a random access preamble assignment for communication with the target base station 5 may be transmitted to the UE 3 in step S505.
MSG1 and/or MSG 3 may be used by the UE 3 to request on-demand SI from the base station 5.

Scheduling Request (SR) and Buffer Status Reports (BSR)
A buffer status report (BSR), that indicates an amount of uplink data in a buffer of the UE 3, may be transmitted from the UE 3 to the base station 5. The network is then able to determine, based on the BSR received from the UE 3, uplink communication resources (e.g. radio resources, including frequency and/or time resources) to allocate to the UE 3 for transmission of the uplink data. The allocated uplink communication resources can be indicated to the UE 3 using a corresponding Uplink Grant message transmitted to the UE 3.

　　A number of different possible formats can be used for a BSR. The format (e.g. number of bits used to indicate the amount of uplink data in a buffer of the UE 3) used for the BSR may depend on how the transmission of the BSR is triggered, which can be different for regular BSR, periodical BSR and padding BSR. The BSR may indicate an amount of uplink data in a buffer of the UE 3 for a particular logical channel (LCH) or logical channel group (LCG), and the format of the BSR may depend on the number of LCGs that have uplink data available for transmission. For a padding BSR, which is transmitted when a number of padding bits are available for transmission of the BSR, the format of the BSR may depend on the number of available padding bits.

　　A logical channel may be identified using a corresponding logical channel ID (LCID), and the LCID may be used to indicate a format of the BSR. An extended LCID (eLCID) may also be provided (for example using a number of bits following the LCID, e.g. 8 bits) that extends the range of the LCID field. For example, an LCID value of 61 may indicate that the BSR is a short BSR, a value of 62 may indicate that the BSR is a long BSR, a value of 59 may indicate that the BSR is a short truncated BSR, and a value of 60 may indicate that the BSR is a long truncated BSR. The LCID may be included in a MAC subheader of a transmission from the UE 3 to the base station 5.

　　The BSR is received at the base station 5, and may be used by the base station 5 to configure and/or schedule uplink resources for transmission of uplink data from the UE 3 to the base station 5. For example, in configured grant Type 1, an uplink grant is provided via an RRC transmission, and stored as a configured uplink grant. In configured grant Type 2, an uplink grant is provided via physical downlink control channel (PDCCH), and stored or cleared (e.g. deactivated) as a configured uplink grant based on L1 signalling indicating configured uplink grant activation or deactivation. Type 1 and Type 2 are configured by RRC for a Serving Cell per bandwidth part (BWP). Multiple configurations can be active simultaneously in the same BWP. For Type 2, activation and deactivation are independent among the Serving Cells. For the same BWP, the MAC entity can be configured with both Type 1 and Type 2. The base station 5 may also (or alternatively) perform semi-persistent scheduling (SPS) or dynamic grant (DG).
Further examples of BSR are provided in Technical Specification (TS) 38.321 V17.0.0.

Scheduling Request (SR)
A further mechanism for requesting uplink resources for use by the UE 3 is the transmission of a scheduling request (SR) from the UE 3 to the base station 5. The UE 3 may transmit the SR using the PUCCH, or in UCI in the PUSCH. The SR is a physical layer transmission for requesting transmission of UL grant by the network, so that the UE 3 can subsequently transmit corresponding uplink data (e.g. using PUSCH). The SR can be used to request the uplink resources for transmitting the BSR.

　　The UE 3 may transmit a SR to the base station 5 when the UE 3 has uplink data to transmit, but does not have a configured UL grant. Alternatively, the UE 3 may periodically transmit a SR to the base station 5 (e.g. based on a timer). The periodicity of the SR transmissions from the UE 3 to the base station 5 may be configured using RRC transmissions from the base station 5 to the UE 3.

　　If PUCCH resources have not been configured for a UE 3 for transmission of the SR, then the UE 3 may use the random access procedure in order to request the PUCCH resources.
Transmission of a SR may be triggered by uplink data for a particular logical channel being queued in a buffer at the UE 3. The SR may then be transmitted using PUCCH resources that have been configured for that logical channel, or for a group of logical channels. The SR has a pending status following transmission of the SR, which is then cancelled after the corresponding uplink resources (e.g. PUSCH resources) have been allocated to the UE 3.

　　The time resources (time resources for the PUCCH) for use by the UE 3 to transmit the SR can be configured by the base station 5. The base station 5 may transmit an indication of a periodicity (e.g. SR-periodicity) and time offset (e.g. SR-offset) for transmission of the SR. The periodicity configured for the SR may be between, for example, 2 symbols and 640 slots, depending on the particular latency requirements and the available communication resources in the time and frequency domains. A minimum time between consecutive SR transmissions may also be configured for the UE 3 by the base station 5, for example using a timer (e.g. sr-ProhibitTimer).

HARQ Feedback
During wireless communication some of the transmitted packets may be lost, or may be subject to errors introduced by noise or interference. The Hybrid Automatic Repeat Request (HARQ) procedure can be used to mitigate against such packet losses and errors using re-transmission (or selective re-transmission) of data packets. For example, the UE 3 may receive a transmission from a base station that includes errors or missing packets. The UE 3 may attempt to correct errors in the received transmission where possible, and may provide feedback to the base station 5 regarding the transmission that has been received, for example including an acknowledgement (ACK) or negative acknowledgement (NACK). Based on the feedback, the base station 5 may determine to re-transmit some or all of one or more original transmissions. The HARQ procedure may include a number of simultaneous HARQ processes, each used for a respective part of one or more transmissions. Therefore, when the base station 5 is awaiting feedback from the UE 3 corresponding to a particular HARQ process (and therefore to a particular part of the transmission), the base station 5 can continue transmission of data for the other HARQ processes.

　　Fig. 7 shows an example of a procedure in which HARQ feedback is transmitted by a UE 3. In step S701, a downlink transmission from the base station 5 is received at the UE 3. After receiving the downlink transmission, the UE 3 performs a HARQ procedure and, in step S702, transmits HARQ feedback to the base station 5. Based on the feedback (e.g. ACK or NACK) received from the UE 3 in step S702, the base station 5 may determine re-transmit some or all of the original transmission.

　　Fig. 8 shows an example in which downlink control information (DCI) is transmitted to the UE 3 in order to enable HARQ feedback. In this example, the UE 3 may initially be configured to have HARQ feedback disabled, and downlink control information is used to enable HARQ feedback for a downlink transmission. Alternatively, the UE 3 may initially be configured to have HARQ feedback enabled, and the downlink control information can be used to disable HARQ feedback for a downlink transmission.

　　In step S801, downlink control information is transmitted from the base station 5 to the UE 3. The downlink control information includes an indication that HARQ feedback is to be enabled/disabled for a HARQ process. If the HARQ feedback is to be enabled, then in response to receiving the downlink control information the UE 3 enables HARQ feedback for the HARQ process. In step S802 the UE 3 receives a downlink transmission from the base station 5. In step S803, the UE 3 transmits corresponding HARQ feedback to the base station 5. The base station 5 can enable HARQ feedback to be transmitted by the UE 3 even when HARQ feedback is initially disabled; therefore, in this example the UEs 3 can initially be configured to have HARQ feedback disabled (which reduces the power consumption of the UE 3), and then enable HARQ feedback in response to signalling received from the base station 5. For example, the base station 5 may determine to transmit downlink control information to enable HARQ feedback when the communication link between the base station 5 and the UE 3 is particularly unreliable. Similarly, if the HARQ feedback is to be disabled, in response to receiving the downlink control information, the UE 3 disables HARQ feedback for the HARQ process. In this case, the UE may not transmit HARQ feedback to the base station. Alternatively, the UE may transmit NACK to the base station corresponding to the HARQ process with feedback disabled, regardless the decoding results of the corresponding PDSCH.

　　The downlink control information transmitted in step S801 may enable/disable HARQ feedback for a HARQ process for a particular downlink transmission, or for a set of downlink transmissions. In one example, the base station 5 may transmit the downlink control information 51 to enable/disable HARQ feedback for a particular type of transmission from the base station 5 to the UE3. For example, the base station 5 may transmit downlink control information to enable HARQ feedback for an important or critical message to be transmitted to the UE 3 (and therefore feedback for increasing the likelihood that the message can be successfully received at the UE is desirable). For example, the base station 5 may transmit downlink control information to enable HARQ feedback for a downlink transmission that comprises a Physical Downlink Shared Channel (PDSCH) transmission that carries a radio resource control (RRC) message, or medium access control control-element (MAC CE). The MAC CE may be, for example, for a Buffer Status Report (BSR) or a Timing Advance Command.

DCI
Types of DCI that may be transmitted from the base station 5 to the UE 3 will now be described in more detail.

DCI 4_0
DCI format 4_0 is used for the scheduling of PDSCH for broadcast in a cell. In other words, DCI format 4_0 is a DCI for broadcast. DCI format 4_0 may alternatively simply be referred to as DCI 4_0. DCI 4_0, and corresponding PDCCH configurations, may be used to transmit a broadcast to a UE 3 in the RRC connected state, RRC inactive state, or RRC idle state. DCI 4_0 may be transmitted with a cyclic redundancy check scrambled by MBMS point-to-multipoint Control Channel (MCCH) radio network temporary identifier (RNTI), MCCH-RNTI, or group-RNTI (G-RNTI) for a multicast traffic channel (MTCH) configured by MBS session information (e.g. MBS-SessionInfo). DCI 4_0 includes a frequency domain resource assignment

　　DCI 4_0 includes a time domain resource assignment. The time domain resource assignment is used to indicate a slot offset, PDSCH mapping type, starting symbol, and number of allocated symbols. This information may be indicated using a lookup table (the time domain resource assignment may comprise a pointer to a lookup table). DCI 4_0 includes a virtual resource block (VRB) to physical resource block (PRB) mapping. The VRB to PRB mapping is a field used to indicate whether the PDSCH uses a non-interleaved VRB to PRB mapping, or an interleaved VRB to PRB mapping. In a non-interleaved mapping, an index for a particular VRB is mapped to a PRB having the same index. In an interleaved mapping, a function is used to map the index for a particular VRB to the corresponding PRB index.

　　DCI 4_0 includes an indication of a modulation and coding scheme (MCS), which may be in the form of a pointer to a lookup table. DCI 4_0 includes a redundancy version (RV) that indicates a corresponding puncturing pattern. DCI 4_0 includes an MCCH change notification if the CRC of DCI 4_0 is scrambled by MCCH-RNTI.

　　It will be appreciated that a modified version of DCI 4_0 may be used in which some of the above described information (such as the MCCH change notification) is omitted where appropriate.

　　In contrast to DCI 4_1 and DCI 4_2 described below, DCI 4_0 does not include fields indicating HARQ scheduling information for UEs 3 in the RRC connected state. For example, DCI 4_0 does not include a new data indicator (NDI), HARQ process number, or an indication of HARQ frequency or time resources.

DCI 4_1
　　DCI format 4_1 (and corresponding PDCCH configurations) is used for multicast transmission. DCI format 4_1 may alternatively simply be referred to as DCI 4_1. The same transmission configuration index (TCI) state as the TCI state for unicast PDCCH may be used when DCI 4_1 is used. DCI 4_1 includes a frequency domain resource assignment, time domain resource assignment, VRB to PRB mapping, MCS and RV as described above for DCI 4_0.

　　DCI 4_1 also includes a HARQ process number that indicates a corresponding HARQ process. DCI 4_1 may include a new data indicator (NDI) that is used to indicate if the resource allocation is for a retransmission, or for a new transmission. DCI 4_1 includes a PUCCH resource indicator that indicates that the UE 3 is to use a particular PUCCH resource when returning HARQ acknowledgements. If the UE 3 has been configured with dedicated PUCCH resources, then the PUCCH resource indicator may indicate one of those resources. The PUCCH resource indicator may be in the form of a 3-bit field. DCI 4_1 includes a PDSCH to HARQ feedback timing indicator that indicates the number of slots between reception of the PDSCH and transmission of HARQ feedback. The PDSCH to HARQ feedback timing indicator may be in the form of a 3-bit field.

　　It will be appreciated that a modified version of DCI 4_1 may be used in which some of the above described information is omitted, where appropriate.

DCI 4_2
　　DCI format 4_2 is used for the scheduling of PDSCH. DCI format 4_2 may alternatively simply be referred to as DCI 4_2. DCI 4_2 for multicast MBS includes a TCI state for PDSCH reception.
DCI 4_2 may be transmitted with a cyclic redundancy check scrambled by G-RNTI, configured by G-RNTI configuration information (e.g. G-RNTI-Config), or group-configured scheduling-RNTI (G-CS-RNTI).

　　DCI 4_2 includes a frequency domain resource assignment, time domain resource assignment, VRB to PRB mapping, PRB bundling size indicator, rate matching indicator, zero power channel status information reference signal (ZP-CSI-RS) trigger, HARQ process number, downlink assignment index, PUCCH resource indicator, PDSCH-to-HARQ feedback timing indicator, and indication of antenna ports, a transmission configuration indication, a demodulation reference signal (DMRS) sequence initialization, priority indicator and enabling/disabling HARQ-ACK feedback indication (in which a value of 1 indicates enabling HARQ-ACK feedback and a value of 0 indicates disabling HARQ-ACK feedback).

　　It will be appreciated that a modified version of DCI 4_2 may be used in which some of the above described information is omitted, where appropriate. The size of DCI 4_2 is configurable and may be, for example, between 20 bits and 140 bits.
DCI 4_0, DCI 4_1 and DCI 4_2 are described in more detail in 3GPP TS 38.212 V17.3.0.

CSI and CSI-RS
The base station 5 is operable to transmit reference signals (RS) in one or more cells 9 that it operates. These reference signals include channel state information RS (CSI-RS). The CSI-RS may be used by the UE 3 for a number of different purposes including, for example, CSI reporting in which the UE 3 derives channel state information (CSI) including one or more channel quality indicators (CQI), rank indicators (RI), and/or precoding matrix indicators (PMI) from CSI-RS measurements and reports them to the base station 5 in a CSI report. The CQI is an index (typically 4 bits) value representing a signal to interference and noise ratio (SINR). The CQI value also corresponds to a modulation and coding scheme (MCS) to be used for each layer. The RI indicates a number of MIMO transmission layers requested by the UE 3 (albeit the base station 5 might not necessarily use the requested number of MIMO transmission layers). The PMI is used by the UE 3 to report parameters defining a preferred precoding matrix to be applied for downlink transmissions (albeit the base station 5 may not use the requested precoding). A layer indicator (LI) may also be included in the CSI report for identifying the strongest layer from the set of layers indicated by the RI.

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

　　The CSI reporting configuration for CSI can be periodic (P-CSI) using PUCCH, aperiodic (A-CSI) using PUSCH, or semi-persistent (SP-CSI) using PUCCH and DCI-activated PUSCH. In periodic CSI reporting, the reporting time periods (i.e. the time periods defining the reporting points) are determined at a higher layer, using RRC signalling and, at the appropriate junctures, CSI data is transmitted, by the UE 3 to the scheduler (base station 5), using PUCCH; whereas, in aperiodic reporting, CSI feedback is triggered as required by the base station 5, using DCI over the PDCCH. In this case, the CSI data is transmitted by the UE 3 over the PUSCH. A-CSI may form the principal CSI feedback framework of a communication system, or it may be a supplementary configuration, and triggered, for example, to deal with a failed detection of P-CSI or SP-CSI reporting.

　　CSI-RS may either be either zero power (ZP-CSI-RS) or non-zero power (NZP-CSI-RS). ZP-CSI-RS are empty resource elements, used primarily for interference measurement. NZP-CSI-RS are used for most of the procedures including channel measurement, beam management, beam measurement, connected mode mobility etc. A non-zero-power CSI-RS may be configured, for example, using a NZP-CSI-RS-Resource information element (IE), or using a CSI-RS-Resource-Mobility field in an CSI-RS-ResourceConfigMobility IE. NZP CSI-RS can be used for interference measurement (IM), for example as part of determining a Signal to Interference plus Noise Ratio (SINR). For cases in which interference is likely to be primarily due to inter-cell interference, CSI IM resources may be used. These resources may be used to measure background interference originating from neighbouring cells. The UE 3 may be provided a configuration for receiving (and measuring) the CSI-RS from the base station 5 (e.g. using a CSI Report Configuration, CSI-ReportConfig, transmitted from the base station 5 to the UE 3).
There are also several other ways in which the CSI-RS may be used including, for example, for connected mode mobility, radio link failure (RLF) detection, beam failure detection / recovery, and fine timing of time and/or frequency synchronisation.

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

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

　　The base station 5 can also configure the UE 3 to provide CSI reports based on different report timing configurations (e.g., using the CSI-ReportConfig IE). For example, the UE 3 may be configured for persistent reporting, semi-persistent reporting on the PUSCH, semi-persistent reporting on the PUCCH, or aperiodic reporting. Aperiodic reporting and semi-persistent reporting on PUSCH may be triggered using a PUSCH DCI. For example, DCI (e.g., using DCI format 0_1) may trigger aperiodic reporting by providing a CSI request that points to a respective index of each of one or more corresponding aperiodic trigger states (e.g., configured in the CSI-AeriodicTriggerStateList IE). Each of these trigger states is associated with one or more corresponding CSI report configurations (e.g., identified by one or more associated CSI-ReportConfig IEs). Semi-persistent reporting on PUSCH may be triggered in a similar way (e.g., by identifying one or more CSI-ReportConfig IEs of one or more CSI-SemiPersistentOnPUSCH-TriggerStates). Semi-persistent reporting on PUCCH may be triggered using a MAC CE.

　　Each CSI report configuration may identify a CSI resource configuration (e.g., using the CSI-ResourceConfigId IE) for measurement (e.g., channel measurement). The identified CSI resource configuration is defined by a corresponding IE (e.g., using the CSI-ResourceConfigId IE) that includes a list of identifiers corresponding to one or more sets of CSI resources (e.g. a list of one or more NZP-CSI-RS-ResourceSetIDs for non-zero power CSI-RS) and associated configuration information. The associated configuration information may, for example, identify an associated bandwidth part (e.g., by means of the bandwidth part ID, BWP ID) and a resource type (e.g., by means of the resourceType IE). The identified resource type may, for example, identify the CSI-RS resource to be a periodic, a semi-persistent, or an aperiodic type. Each resource set comprises one or more specific CSI resource configurations represented by associated identifiers (e.g. one or more NZP-CSI-RS-ResourceIDs for non-zero power CSI-RS) that each point to the specific configuration information (e.g. defined by an NZP-CSI-RS-Resource IE for non-zero power CSI-RS) for that CSI resource configuration). Accordingly, the base station 5 can configure multiple CSI report configuration instances and CSI resource configuration instances. It will be appreciated that multiple resource sets can be configured per CSI resource config for the case of aperiodic CSI RS resources. In this way reporting of specific CSI resource sets for specific use cases may be configured. For example, a CSI-RS resource set may be configured that includes CSI-RS resources for different beams for beam management purposes. A CSI-RS resource set may be configured that includes a single CSI-RS resource for a number, N, of ports for channel estimation purposes.

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

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

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

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

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

　　The UE 3 may be configured to select a set of CSI to be reported to the base station 5. The UE 3 may be configured to determine to select the best m CSIs to report to the base station 5 in a measurement report. The value of m may be configurable by the base station (e.g. using any suitable transmission from the base station 5 to the UE 3).

Discontinuous Reception (DRX)
　　Methods of discontinuous reception (DRX) and/or discontinuous transmission (DTX) may be performed at a UE 3 or at a base station 5. For example, a UE 3 or access network node 5 may be configured to operate in an energy saving mode (which may also be referred to as a sleep mode) in which the device performs a reduced number of transmissions, or in which the device is configured not to attempt to transmit or receive signals during a particular time period.

　　A UE 3 may be configured to operate using a 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 (which may be referred to as a DRX-active state) and "OFF durations" in which the UE 3 is not configured for receiving transmissions (which may be referred to an a DRX-inactive state), e.g. transmissions from the base station 5. During the OFF durations, the physical layer processing may be turned off within the UE 3. Beneficially, the energy consumption of the UE 3 is reduced in the periods in which the UE 3 is not configured for receiving transmissions.

　　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. 9.

　　The UE 3 is typically provided with its DRX configuration by or via the base station 5. A DRX configuration provided to the UE 3 (for example, using a DRX configuration information element (IE) included in a transmission from the base station 5 to the UE 3) may include 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 base station 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 is to remain configured for receiving transmissions following the reception of a PDCCH.

　　DRX may be configured per UE 3 by the network (e.g. via any suitable signalling from the base station 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 base station 5 in a corresponding cell. The base station 5 may nevertheless be configured for reduced or limited transmission/reception in the cell during the OFF duration of the DRX cycle. For example, the base station 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.

　　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 base station 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 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.

　　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)).

　　A DRX configuration may include a long DRX cycle in which the time between the ON durations is relatively large (t2 shown in Fig. 9 is relatively large), and a short DRX cycle in which the time between the ON durations is relatively small (t2 shown in Fig. 9 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 base station 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 signaling from the base station 5 (or alternatively could be preconfigured in the UE 3).

　　Whilst DRX has been described above with reference to discontinuous reception performed by the UE 3, a similar DTX/DRX pattern can be defined to control the discontinuous transmission/reception of data by the base station 5. Discontinuous operation of one or more base station cells - is referred to as "cell DTX/DRX".

Cell DTX/DRX can operate in substantially the same way as UE DTX/DRX - stopping the base station's transmissions and receptions during periods of time (OFF duration) when the base station 5 is inactive or asleep (a 'DRX inactive state') and resuming transmissions and receptions with the UEs 3 during periods of time (ON duration) when the base station 5 is active (a 'DRX active state'). 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 duration (t1), the OFF duration (t2) and the number of cycles etc.

The UE 3 may be configured to not transmit (or to have a reduced number of transmissions) during the OFF duration of the base station 5. For example, if a period in which a scheduling request (SR) would normally be transmitted by the UE 3 to the base station 5 falls within the DRX inactive period of the base station 5, then the UE 3 may be configured to delay (or 'defer') transmission of the SR (without triggering a random access procedure including RACH) until the base station 5 is in the DRX active mode (the UE 3 maintain the SR as pending until the base station 5 is in the DRX active state). Other transmission that the UE 3 may determine not to transmit when the base station is in the DRX inactive state include: periodic or semi-persistent CSI reports; periodic or semi-persistent sounding reference signals (SRS); or HARQ feedback for semi-persistent scheduling (SPS) PDSCH. A set of transmissions, or types of transmission, that the UE 3 is configured not to transmit when the base station 5 is in the DRX inactive state may be configurable by the network (e.g. via any suitable transmission from the base station 5 to the UE 3).

　　However, as will be described in more detail later, the UE 3 may be configured to nevertheless transmit certain transmissions during the OFF duration of the base station 5. For example, UE 3 may be configured to transmit one or more high priority transmissions during the DRX inactive period of the base station 5. The high priority transmissions may include, for example, URLLC transmissions, transmissions for beam management reporting (e.g. RSRP-based CSI reporting), radio link failure (RLF) and/or beam failure related transmissions; and transmissions for handover procedures (e.g. measurement reports). In order to enable transmission of the high-priority transmissions by the UE 3 when the base station 5 is in the DRX inactive state, the UE 3 may be configured to transmit corresponding scheduling requests, CSI reports, PRACH transmissions and/or configured grant transmissions during the DRX inactive period. Particularly advantageous methods of scheduling and transmitting uplink transmissions during periods in which the base station 5 is in the DRX inactive state will be described in more detail later.

Uplink WUS
A wakeup signal (WUS) may be transmitted from the UE 3 to the base station 5 in order to 'wake up' the base station 5 (e.g. to request a transition of a cell from no or reduced transmission/reception activity to an active transmission or reception of a channel/signal). This type of WUS may be referred to as an uplink WUS. The uplink WUS may be transmitted from the UE 3 to the base station 5 in order to trigger or request, for example, the transmission of SSB, SIB1 and/or reference signals by the base station 5. For example, the base station 5 may be configured to perform discontinuous transmission or reception and the uplink WUS may be used to request or trigger the transmission or reception of a signal that would not normally be transmitted/received by the base station 5 during the discontinuous transmission/reception.

PUCCH and Cell DRX
　　Fig. 10 shows an example in which PUCCH resources are scheduled during a period in which the base station 5 is in the DRX inactive state. Fig. 10 shows resources for uplink transmissions by the UE 3 in the time and frequency domain. It will be appreciated that the units of time illustrated in Fig. 10 could be any suitable unit of time (e.g. slot or symbol). Similarly, it will be appreciated that the units of frequency in Fig. 10 could be any suitable unit of frequency (e.g. resource blocks). In the example of Fig. 10, resources for the transmission of scheduling requests by UEs 1 to 4, and channel state information for UE 1 and UE 3, are shown.

　　The PUCCH can be used by the UE 3 for the transmission of uplink control information (UCI). The UCI may comprise HARQ acknowledgements (feedback), scheduling requests (SR), and periodic or semi-persistent CSI reports. The PUCCH may have various formats depending on the information to be included in the PUCCH transmission. For example, PUCCH formats 0 and 1 are designed for smaller payloads, and can be used for transmission of one or two HARQ acknowledgements and a scheduling request. PUCCH formats 2, 3 and 4 can be used for the transmission of larger payloads and can be used for the transmission of HARQ acknowledgements, SR and CSI reports. In the time domain, PUCCH format 0 may have a duration of 1 or 2 symbols, and PUCCH format 1 may have a duration of 4 to 14 symbols. PUCCH format 2 may have a duration of 1 or 2 symbols. PUCCH format 3 may have a duration of 4 to 14 symbols, and PUCCH format 4 may also have a duration of 4 to 14 symbols. In the frequency domain, one resource block may be used for PUCCH formats 0, 1 and 4. For PUCCH formats 3 and 4, 4 to 14 resource blocks may be used. It will be appreciated that the UE 3 uses the appropriate PUCCH format depending on whether the UE 3 is to transmit HARQ feedback, SR or CSI reports, or any combination thereof. The time and frequency resources for transmission of the PUCCH (which may be cell-specific PUCCH configuration information) can be indicated to the UE 3 by the base station 5 using any suitable transmission (e.g. using SIB, via PUCCH configuration information included in SIB1).

　　As illustrated in the figure, the base station 5 that is receiving the transmissions from the UEs 3 is configured with a time period in which the base station 5 is in the DRX active state, and a time period in which the base station 5 is in the DRX inactive state. However, in this example, the base station has nevertheless determined to receive uplink transmissions from the UE 3 during the DRX inactive period (e.g. because the transmissions correspond to high priority transmissions, as described above). In this example, the configuration of time and frequency resources for transmission of the scheduling request and channel station information is the same in the DRX inactive period as for the DRX active period. Whilst this enables the high priority uplink transmissions to be performed, there are relatively large number of time occasions in which the base station 5 is to receive a transmission from the UE 3 (in other words, there are few empty columns in the grid of communication resources illustrated in Fig. 10). This can occur due to the relatively short periodicity of transmissions of the uplink control information (UCI), and the sparse distribution of the UCI from different UEs 3 in the time domain (which may be performed for improved load balancing).

　　It will be appreciated that whilst in the example of Fig. 10 the duration of the time period in which the base station 5 is configured to be in the DRX active state is the same as the duration of the time period in which the base station 5 is configured to be in the DRX inactive state, this need not necessarily be the case. It will also be appreciated that when the base station is in the DRX inactive state, the base station 5 nevertheless receives the uplink transmissions illustrated in Fig. 10 during the DRX inactive period using the uplink resources configured by the base station 5. In other words, the DRX inactive period is a period designated as a period in which the base station 5 is normally DRX inactive (and not receiving uplink transmissions from the UEs 3), but the base station 5 can nevertheless receive the scheduled uplink transmissions during the DRX inactive period (by temporarily, during the DRX inactive period, entering a state in which the base station 5 is configured for receiving the uplink transmissions). The time resources for reception of the uplink transmissions using the PUCCH in the DRX inactive period are known at the base station, since the timing of the uplink transmissions is based on scheduling information for the PUCCH provided to the UEs 3 by the base station 5.

　　Fig. 11 shows a modified version of Fig. 10 in which the resources used for the uplink transmissions in the DRX inactive period have been re-allocated for improved energy savings. As shown in Fig. 11, in this example the uplink transmissions in the DRX inactive period have been scheduled to overlap in the time domain (e.g. within a single slot). Advantageously, therefore, the time duration over which the base station 5 receives the uplink transmissions from the UEs 3 during the DRX inactive period is reduced (in the example of Fig. 11, minimised), resulting in improved energy savings. In other words, in the example of Fig. 11 there are fewer interruptions (in the time domain) in which the base station 5 receives uplink transmissions in the DRX inactive period.

PUCCH Configuration
　　The base station 5 may configure a UE 3 with a set of N PUCCH resources (in the time and frequency domains, as illustrated in figures 10 and 11) for uplink transmissions. An indication of PUCCH resources configured for the UE 3 may comprise a PUCCH resource ID, a PUCCH frequency allocation (e.g. starting resource block, and number of resource blocks), and the PUCCH format type. The UE 3 can determine, based on the indication of the PUCCH resources, how many bits can be carried over the configured PUCCH resources. The indication of the PUCCH resources may also comprise an indication of a number of slot repetitions for the PUCCH transmission, an indication of whether frequency hopping is enabled, and an indication of symbols within one or more slots in which the PUCCH is configured.

　　For scheduling requests (SR) and channel state information (CSI) reporting, which may be periodic or semi-persistent, the base station 5 may provide the UE 3 with uplink control information (UCI) configuration information. The UCI configuration information may be provided for each type of report (e.g. per type of report). A first number of PUCCH resources may be configured for SR, and a second number of resources may be configured for the CSI reports. Multiple PUCCH resource configurations may be provided for SR for different logical channels. Similarly, multiple PUCCH resource configurations may be provided for CSI reports for different CSI report types. Each PUCCH resource configuration includes an allocation in the time domain (e.g. slot offset and periodicity) of where the SR and/or CSI report is to be transmitted. The UE 3 is configured to transmit the SR and/or CSI using the allocated resources.

　　As described above with reference to Fig. 7, the UE 3 may be configured to transmit HARQ feedback corresponding to a downlink transmission (e.g. PDSCH) received from the base station 5. Whilst the examples of figures 10 and 11 show uplink transmissions corresponding to SR and CSI, the uplink transmissions could also include HARQ feedback. For HARQ feedback for PDSCH, the base station 5 may provide an indication of the PUCCH resources in the time and frequency domains for the uplink transmission of the feedback. The PUCCH resources for the HARQ feedback may be indicated to the UE 3 via, for example, RRC configuration information transmitted to the UE 3 from the base station 5. The network may configure (e.g. via transmissions from the base station 5 to the UE 3) a set of values for DL data to an ACK field within the RRC configuration for the HARQ report. One of the values of the set is selected by the DCI. During initial UE setup, the network may configure, for the UE 3, N, values of a "DL data to HARQ ACK delay" parameter via RRC configuration. To indicate the actual timing of HARQ feedback transmission (relative to PDSCH reception) to the UE 3 dynamically, base station 5 may select one of the N values for the delay, and transmit an indication of the selected value to the UE within the DCI that schedules the corresponding PDSCH.

　　A PUCCH configuration for a UE 3 may be indicated to the UE 3 using PUCCH Configuration information (e.g. PUCCH-Config). The PUCCH configuration information may include lists for adding and releasing PUCCH resource sets (e.g. resourceSetToAddModList). The PUCCH configuration information may include lists for adding and releasing PUCCH resources applicable for the UL BWP and serving cell in which the PUCCH-Config is defined - the defined resources may be referred to from other parts of the configuration to determine which resource the UE 3 is to use for which report. The PUCCH configuration information may comprise parameters that are common for all PUCCH resources of a particular format (e.g. formats 1 to 4). The PUCCH configuration information may provide an indication of a time between a PDSCH and transmission of a corresponding ACK transmission. The PUCCH configuration information may also comprise an indication of a spatial relation between a reference RS and the PUCCH - the reference RS may be SSB, CSI-RS or SRS.

　　The PUCCH configuration information may also comprise an indication of a PUCCH resource set (e.g. PUCCH-ResourceSet). The resource set may be indicated using a corresponding resource set ID. The indication of the PUCCH resource set may comprise a list of PUCCH resources, and the UE 3 may be configured to select one of the PUCCH resources from the list for an uplink transmission. The PUCCH configuration information may also include an indication of a maximum payload size that the UE 3 may transmit using the PUCCH resource set. In a PUCCH occurrence, the UE 3 may be configured to select the first PUCCH resource of the PUCCH resource set which supports the number of bits that the UE is to transmit.

　　The PUCCH configuration information may also comprise an indication of a starting PRB, an indication of whether intra-slot frequency hopping is enabled, and an index of a starting PRB for a second hop of PUCCH in the case of frequency hopping.

MAC SR Procedure
　　For each SR configuration, the base station 5 may configure a set of logical channels that are associated with the SR configuration. If a BSR is triggered for one of the logical channels, the UE 3 is configured to use the SR configuration for transmission of the SR (e.g. during the DRX inactive period of the base station 5) for that logical channel. The SR may be triggered if a BSR is triggered and there are no available PUSCH for the UE 3. The SR configuration may also be applied for recovery procedures such as listen before talk (LBT) failure or secondary cell (Scell) beam recovery. For each SR, the UE 3 may be configured to continue to transmit the SR transmissions on the PUCCH based on a timer, e.g. following the expiry of the 'SR-prohibit' timer. The UE 3 may determine to stop the transmissions of the SR on the PUCCH if a configured maximum number of SR transmissions have been performed, or if the BSR is transmitted by the UE 3. When the SR is triggered the UE 3 may initiate a random access procedure (described above with reference to Fig. 6) including RACH transmission if no PUCCH resources are available for the UE 3 for transmission of the SR. The UE 3 may also initiate a random access procedure including RACH transmission when the UE 3 reaches a maximum number of SR transmission attempts without receiving an UL grant from the base station 5.

SR Resource Configuration
　　The base station 5 is configured for transmission of SR resource configuration information to the UE 3. The SR resource configuration information may comprise an ID of the scheduling request configuration that uses the schedule request resource (e.g. schedulingRequestID). The SR resource configuration information may comprise an indication of a scheduling request resource ID (e.g. schedulingRequestResourceID). The SR resource configuration information may comprise an indication of the SR periodicity and offset in number of slots. The configured periodicity may depend on the chosen subcarrier spacing. For example, for a subcarrier spacing (SCS) of 15 kHz, the periodicity may be 2 symbols, 7 symbols, 1 slot, 2 slots, 4 slots, 5 slots, 8 slots, 10 slots, 16 slots, 20 slots, 40 slots or 80 slots. Similarly, for example, for an SCS of 120 kHz, the periodicity may be 2 symbols, 7 symbols, 1 slot, 2 slots, 4 slots, 8 slots, 16 slots, 40 slots, 80 slots, 160 slots, 320 slots or 640 slots.

UCI and Cell DRX Inactive - Physical Channel Configuration
　　Particularly advantageous methods for reducing the number of time occasions in which the base station 5 is to receive uplink transmissions during a DRX inactive period will now be described.
　　Fig. 12 shows an example in which a configuration of communication resources for uplink transmissions in the DRX active period is different from a configuration of communication resources for uplink transmissions in the DRX inactive period, and some uplink transmissions have been disabled during the DRX inactive period, beneficially improving network energy savings in the DRX inactive period whilst still enabling reliable communication for high priority transmissions. In the illustrated example, uplink communication resources have been scheduled, in the time and frequency domains, for SR transmission using first and second SR configurations (SR config-1 and SR-config-2), and for CSI transmission using first and second CSI configurations (CSI Config-1 and CSI Config-2), during the DRX active period. In contrast, only uplink transmissions for SR corresponding to the first SR configuration and CSI corresponding to the first CSI configuration are scheduled during the DRX inactive period. As illustrated in Fig. 12, the number of time occasions in which the base station 5 is to receive uplink transmissions during the DRX inactive period is beneficially reduced (compared to the DRX active period), improving energy saving.

　　The configuration (e.g. indication of time and frequency resources) for the uplink transmissions in the DRX inactive period could be indicated either explicitly or implicitly to the UE 3. For example, the base station 5 may provide an explicit indication of the time and frequency resources for transmission of the SR or CSI (or any other suitable UCI or uplink transmission, e.g. including HARQ feedback) in the DRX inactive period. The time and frequency resources for the uplink transmissions in the DRX inactive period could alternatively be indicated relative to the time and frequency resources configured for the corresponding uplink transmissions in the DRX active period, as a so-called 'delta configuration'. Only certain parts of the physical channel configuration for the DRX inactive period may be changed (e.g. time/frequency resources) while the other parameters remain same as in DRX active period. This approach is more data efficient than when a full configuration (including all parameters) for SR and CSI reports are provided for the DRX inactive state.

　　Configuration information for uplink transmissions in the DRX inactive period may include an indication of a difference in a value of a periodicity and/or time offset (e.g. for SR or CSI) with respect to values of those parameters used for a corresponding transmission in the DRX active period. Similarly, a frequency resource for an uplink transmission during the DRX inactive period may indicated by providing an indication of a difference with respect to a frequency resource used for a corresponding uplink transmission in the DRX active period. For example, as illustrated in Fig. 12, the frequency resources allocated by the base station 5 for transmission of the CSI using CSI Config-1 in the DRX active period are different from those for the transmission of the CSI in the DRX inactive period, and the difference in frequency (e.g. number of resource blocks) could be indicated to the UE 3 by the base station 5.

　　In the example shown in Fig. 12, transmission of SR using the second SR configuration (SR config-2) and transmission of CSI using the second CSI configuration (CSI config-2) have been disabled (e.g. not configured by the base station 5) during the DRX inactive period. SR and/or CSI may be disabled during the DRX inactive period based on any suitable control signalling from the base station 5 to the UE 3. For example, particular uplink transmissions may be disabled by explicitly indicating whether the UCI is allowed to be transmitted or not during the DRX inactive period. Alternatively, an implicit indication that an uplink transmission is not to be transmitted during the DRX inactive period may be provided, for example by not providing a parameter value (e.g. periodicity and offset, or PUCCH resource configuration) for the transmission in the DRX inactive period.

　　The UE 3 may be configured to treat each SR or CSI configuration as being disabled during the DRX inactive period unless the UE 3 receives an indication from the base station 5 that the SR or CSI is to be transmitted during the DRX inactive period. In other words, the SR and/or CSI may be disabled by default during the DRX inactive period, unless the transmissions are activated (configured, or allocated resources) by the base station 5 (e.g. using an explicit indication that the SR or CSI is to be transmitted during the DRX inactive period).

HARQ ACK/NACK Feedback Timing
Whilst Fig. 12 illustrates a case in which SR and CSI are transmitted during the DRX inactive period, HARQ ACK/NACK feedback may also be transmitted during the DRX inactive period. Advantageously, in the present example a larger time difference (e.g. greater than 15 slots) between DL data transmission and transmission of the corresponding ACK/NACK feedback is supported, providing greater flexibility for delaying the transmission of the feedback based on the DRX schedule of the base station 5. For example, the ACK/NACK feedback may be delayed so that it does not fall within the DRX inactive period. Alternatively, as will be described in more detail later, the resources for transmission of the ACK/NACK feedback may be configured to overlap with another uplink transmission (e.g. CSI, SR, additional HARQ feedback from the same UE 3 or another UE 3 in the cell of the base station 5, or other UCI) in the time domain, reducing the overall number of time occasions for which the base station 5 is to receive an uplink transmission during the DRX inactive period, and therefore improving energy saving.

　　The time offset for the HARQ feedback may be configured explicitly by the base station 5 using any suitable signalling transmitted from the base station 5 to the UE 3. The UE 3 is configured to add the time offset to the time resource previously configured for the uplink transmission of the feedback, to determine one or more time resources to use for transmission of the feedback. Alternatively, the UE 3 may be configured to derive the time offset for the transmission of the HARQ feedback. For example, the UE 3 may determine the time offset for the transmission of the HARQ feedback based on the remaining duration of the DRX inactive period. The time resources corresponding to the DRX inactive period of the base station 5 (or more generally, the DRX/DTX schedule of the base station 5) may be indicated to the UE 3 by the base station 5. Alternatively, for example, the time offset for the transmission of the HARQ feedback may be indicated to the UE 3 within the DCI that schedules a corresponding PDSCH.

　　The maximum time difference between the transmission of the downlink data and the transmission of the corresponding ACK/NACK feedback by the UE 3 during the DRX inactive period may be larger than the maximum time difference between the transmission of the downlink data and the transmission of the corresponding ACK/NACK feedback during the DRX active period.

　　The time delay for transmission of the HARQ feedback may be configured by updating the HARQ-ACK codebook generation rules. A HARQ ACK codebook defines the format used to signal a set of HARQ feedback to the base station 5. The HARQ codebook may be a semi-static (Type 1) codebook that is fixed in size by information provided via RRC signalling, or may be a dynamic (Type 2) codebook that changes in size depending on the number of resource allocations. The use of a particular codebook by the UE 3 (and by the base station 5) is configured by the base station 5.

　　If a HARQ-ACK codebook corresponds to feedback that would fall within the DRX inactive period of the base station 5 (e.g. based on a PDSCH-to-HARQ feedback timing indicator field, or provided by a dl-DataToUL-ACK information element), then the HARQ-ACK feedback may be delayed to use the next available PUCCH resource that does not fall within the DRX inactive period, or to overlap in the time domain with another uplink transmission during the DRX inactive period. The first uplink symbol of the PUCCH to carry the HARQ-ACK information may be defined using an assigned HARQ-ACK timing parameter, K1, that indicates a time gap between the downlink transmission and the time resource for transmission of the corresponding HARQ feedback. The value of K1 may be configured by the base station 5 using RRC signalling and/or DCI. The value of K1 may be increased (e.g. to 1, 3, 5, 7, 9, 11, 13, or 15 slots) or a higher number of bits can be used to indicate the K1 value to the UE 3 (as compared to values used by a cell not operating with NES) in order to delay the transmission of the HARQ feedback. The value of K1 is configurable per UE 3 by the base station 5, and can advantageously be used to cause HARQ feedback from different UEs 3 to overlap in the time domain in the DRX inactive period, reducing the number of time occasions for which the base station 5 is to receive HARQ feedback during the DRX inactive period (e.g. if the delay required to delay the HARQ feedback until after the DRX inactive period has ended would be too large). Alternatively, for example, the base station 5 could provide an indication of a common time resource (e.g. PUCCH time slot) to be used by a group of UEs 3 (e.g. all UEs 3 in the cell) for transmission of HARQ feedback during the DRX inactive period of the base station 5. In this case, the UE 3 may be configured to determine the value of K1 so that HARQ feedback transmitted by the UE 3 will be transmitted using the common time resource. The indication of the common time resource could be provided to the UE 3 by the base station 5 using any suitable transmission (e.g. via the DCI, or RRC transmissions).

　　Fig. 13 shows an example in which transmission of HARQ feedback is delayed within the DRX inactive period of the base station 5, in order to reduce the number of time occasions for which the base station 5 is to receive uplink transmissions during the DRX inactive period. As shown in Fig. 13, a first PDSCH (PDSCH-1) for a first UE 3 is transmitted during a first time resource. The HARQ feedback corresponding to the first PDSCH is then transmitted during the DRX active period of the base station 5. A delay is provided between the transmission of the first PDSCH-1 and the uplink transmission of the corresponding feedback, shown as "Delay 1" in Fig. 13. A second PDSCH (PDSCH-2) is then transmitted to the UE 3. As shown in Fig. 13, the delay between the second PDSCH and the uplink transmission of the corresponding feedback (shown as "Delay 2" in Fig. 13) is greater than the delay used in the DRX active period. Advantageously, this enables the time resources used for the HARQ feedback in the DRX inactive period to be configured to overlap with time resources used for other uplink transmissions. In the example shown in Fig. 13, the time resources used for the transmission of the HARQ feedback for the second PDSCH are the same as the time resources used for transmission of UCI for another UE 3. The HARQ feedback could be configured to overlap in the time domain with any other suitable uplink transmission in the DRX inactive period, in order to reduce the number of time occasions for which the base station 5 is to receive uplink transmissions during the DRX inactive period, thereby improving energy savings. Whilst in the example illustrated in Fig. 13 the second PDSCH is also transmitted during the DRX inactive period, this need not necessarily be the case. For example, a PDSCH could be transmitted during the DRX active period, and the feedback for the PDSCH transmitted in the DRX inactive period (and configured to overlap in the time domain with another uplink transmission in the DRX inactive period). Alternatively, the PDSCH could be transmitted during the DRX active period, and the transmission of the corresponding HARQ feedback could be delayed until after the end of the next DRX inactive period of the base station (the HARQ feedback could be transmitted in the another DRX active period of the base station, rather than the DRX active period in which the PDSCH is transmitted). Whilst the example of Fig. 13 shows an example in which the HARQ feedback and the UCI for the other UE 3 use the same time resources in the DRX inactive period, it will be appreciated that the time resources need not be exactly the same, but could instead be partially overlapping, which nevertheless reduces the time duration for which the base station 5 receives uplink transmissions during the DRX inactive period.

　　The base station 5 may configure the time resources to be used for uplink transmissions in the DRX inactive period so that HARQ feedback for different PDSCH for a UE 3 (or for different UEs 3) are transmitted using the same, or partially overlapping, time resources. The base station 5 may provide an indication to the UE 3 within DCI for a first PDSCH of whether the HARQ feedback for the first PDSCH is to be transmitted using HARQ feedback time resources corresponding to a second PDSCH (so that HARQ feedback for the first and second PDSCH, which may be for the same UE 3, are transmitted using the same time resources during the DRX inactive period). Transmission of the HARQ ACK/NACK feedback may be delayed to the next time resource (e.g. slot) used for a periodic UCI transmission (e.g. SR/CSI) to be transmitted by the UE 3. The HARQ feedback bits may then be multiplexed with the bits of the periodic UCI transmission.

　　As described above, the base station 5 may configure uplink communication resources to be used for transmission of UCI to overlap in the time domain, to increase energy savings during the DRX inactive period of the base station. The base station 5 may be configured to disable one or more PUCCH resource configurations that would be normally used by the UE 3 (e.g. during the DRX active period). For example, a subset of PUCCH resources or PUCCH resource sets associated with a high payload size could be disabled, to allow for higher resource availability for achieving the overlap in the time domain during the DRX inactive period. In a case where a PUCCH resource for a SR is deactivated, then the UE 3 may initiate RACH for the SR during cell DRX.

　　The base station 5 may enable (e.g. configure or allocate to a UE 3) additional PUCCH resource configurations which are to be used only during the DRX inactive period. An indication, from the base station 5 to the UE 3, that a PUCCH resource configuration is to be used only during the DRX inactive period may be provided within the PUCCH resource configuration, or within an associated configuration for UCI (e.g. SR or CSI) by indicating that a different PUCCH resource configuration is to be used during the DRX inactive period.

　　The network may also provide (e.g. via a transmission from the base station 5 to the UE 3) an indication of a set of parameters for each PUCCH resource to be used during the DRX inactive period of the base station 5. The indicated parameters may comprise an allocation of time and frequency resources, and/or a PUCCH format. The PUCCH configuration ID may remain the same.

　　For semi-persistent CSI transmitted using PUSCH, the PUSCH resources used during the DRX active period of the base station 5 may not be needed during the DRX inactive period, and so mechanisms can be defined in order to reduce the number of PUSCH resources configured for uplink transmissions in the DRX inactive period. The PUSCH transmission parameters (e.g. the frequency resource allocation) may therefore be different for the DRX active period and the DRX inactive period. Alternatively, the base station 5 may provide an indication to the UE 3 that the CSI report that would normally be transmitted using PUSCH is to be transmitted using a PUCCH resource during the DRX inactive period, in which case the base station 5 provides an indication of the PUCCH resource to the UE 3. In a further alternative, a CSI report associated with the PUSCH may be disabled during the DRX inactive period. The CSI report may be disabled explicitly by the base station 5 by providing an explicit indication to the UE 3 using configuration information, or alternatively the disabling of the CSI during DRX inactive periods could be pre-defined at the UE 3.

　　Fig. 14 shows an example in which communication resources for transmission of PUCCH are different between the DRX active period and the DRX inactive period, some PUCCH are disabled during the DRX inactive period, and some PUCCH are only used during the DRX inactive period. As shown Fig. 14, during the DRX active period a first, second and third PUCCH (PUCCH resource-1, PUCCH resource-2 and PUCCH resource-3) are configured during the DRX active period. The frequency resources allocated (configured) for transmission of the first PUCCH in the DRX active period are the same as the frequency resources allocated for transmission of the first PUCCH during the DRX inactive period of the base station 5. However, the frequency resources used for the transmission of the second PUCCH during the DRX active period are different from the frequency resources used for the transmission of the second PUCCH during the DRX inactive period. Moreover, the third PUCCH is disabled during the DRX inactive period. In this example, the third PUCCH is disabled as it carries a relatively large UCI size (and uses a relatively large amount of frequency resources in the DRX active period). As shown in Fig. 14, fourth and fifth PUCCH (PUCCH resource-4 and PUCCH resource-5) are only configured during the DRX inactive period. Advantageously, by configuring the resources available for transmission of each PUCCH, the base station 5 is able to enable a higher level of multiplexing for the UCI transmissions during the DRX inactive period.

Higher Layer Procedures
The base station 5 may provide an indication to the UE 3 of which SR are allowed (e.g. configured or allocated) to be transmitted by the UE 3 during the DRX inactive period of the base station. For example, the base station 5 may provide an indication, within a configuration for the SR, of whether the SR can be transmitted during the DRX inactive period of the base station 5. The base station 5 may configure transmission of some SR to be allowed during the DRX inactive period. For example, the base station 5 may provide an indication to the UE 3 that transmission of SR for SCell beam failure recovery or LBT failure (or other high priority transmissions) is allowed during the DRX inactive period. Alternatively, the base station 5 may provide an indication within a logical channel configuration of whether a SR is allowed to be transmitted during the DRX inactive period or not (e.g. for a SR that is triggered due to a BSR trigger associated with the logical channel). Transmission of SR during the DRX inactive period may also be allowed for particular RRC procedures (e.g. mobility procedures such as handover, described above with reference to Fig. 5). For example, SR transmissions that occur due to a measurement report transmission associated with measurement report triggers may be allowed. The base station 5 may configure the measurement events for which transmission of a corresponding SR during the DRX inactive period of the base station is allowed (by providing any suitable indication to the UE 3).

　　The base station 5 may be in a DTX inactive state when a SR is transmitted by the UE 3, in which case the UE 3 may not monitor cell RNTI (C-RNTI) based transmissions from the network. In this case, the inventors have realised that improved methods can be used in order for the UE 3 to receive UL grants following the SR transmission. In a first option, the UE 3 is configured to monitor for C-RNTI based DCI transmissions or UL grant from the network after the SR is transmitted by the UE 3 during the DTX inactive period of the base station. In a second option, the UE 3 is configured to assume that the DTX inactive state is finished (or not enabled) and monitors all DL transmissions from the base station 5 based on the DTX active state when a SR is transmitted by the UE during the DRX inactive period.

　　Some of the configured grant (CG) resources may be needed during the DRX inactive period (e.g. for the scheduling of high-priority transmissions, such as transmissions related to handover, radio link failure, or beam failure), and so the base station 5 may maintain these resources as being available for uplink transmissions during the DRX inactive period (and may temporarily leave the DRX inactive state in order to receive the uplink transmissions). An indication of the transmission parameters (configuration information for the transmissions), for example the periodicity and offset value, for the CG configuration during the DRX inactive period may be provided, and the parameters may be different from those used during the DRX active period. As described above with reference to SR and CSI, the parameters may be indicated either explicitly or implicitly to the UE 3 from the base station 5 for the DRX active and DRX inactive periods.

MAC SR Procedure
During the DRX inactive period of the base station 5, the UE 3 may be configured not to initiate a random access procedure including RACH transmission due to a SR trigger. However, it can be advantageous to allow initiation of the random access procedure during the DRX inactive period if there are no PUCCH resources available for use by the UE 3 for transmission of the SR (e.g. configured for use by the UE 3 by the base station 5).

　　Fig. 15 shows an example in which RACH transmission is not allowed during the DRX inactive period of the base station 5, and is instead transmitted during a subsequent DRX active period. As shown in Fig. 15, in this example RACH is triggered due to SR during the DRX inactive period of the base station 5, but since the corresponding PRACH transmission is not allowed during the DRX inactive period, the PRACH transmission is delayed until the DRX active period of the base station 5. The corresponding RAR or MSG3 (described above with reference to Fig. 6) are also illustrated in the DRX active period of the base station 5.

　　Fig. 16 shows an example in which RACH transmission is allowed during the DRX inactive period of the base station 5 if the SR that triggered the RACH corresponds to an allowed transmission (e.g. high priority transmission). As shown in Fig. 16, in this example RACH is triggered due to SR that corresponds to a transmission that is allowed during the DRX inactive period, and the PRACH and RAR, MSG3, etc. are transmitted during the DRX inactive period of the base station 5. Advantageously, therefore, high priority transmissions can be received at the base station 5 even during the DRX inactive period.

　　Fig. 17 shows an example in which RACH is triggered due to SR during a DRX active period, but the first available PRACH occasion is within the DRX inactive period. In this example, the RACH trigger due to SR occurs during a DRX active period of the base station 5. However, the first PRACH occasion available for transmission of the corresponding PRACH is within the DRX inactive period of the base station 5. Therefore, the UE 3 determines to delay transmission of the PRACH until a PRACH occasion that is within a subsequent DRX active period of the base station. In other words, the UE 3 waits until the end of the DRX inactive period of the base station 5 that follows the triggering of the RACH due to SR, before transmitting the PRACH. Therefore, transmission of the PRACH can beneficially be avoided during the DRX inactive period of the base station 5.

　　In a further alternative, RACH transmission may be allowed during the DRX inactive period only if the base station 5 provides an indication (either explicitly or implicitly) to the UE 3 that a RACH resource is to be used for a SR (e.g. corresponding to a high priority transmission) during the DRX inactive period of the base station 5.

UCI Multiplexing
If a SR associated with a corresponding SR configuration is not allowed to be transmitted during the DRX inactive period of the base station 5, then an SR bit may not be included within UCI if the SR is disabled by a higher layer.
During the DRX inactive period of the base station, CSI reports may be multiplexed with SR and/or HARQ feedback. The CSI may be multiplexed in order of priority. The CSI reports may be CSI reports for, for example, tracking (tracking reference signal - TRS), radio link monitoring (RLM), beam failure detection/recovery, radio resource management (RRM) or beam management. The order of priority for the multiplexing may be, for example:
1)　　Tracking (TRS)
2)　　RLM
3)　　Beam failure detection/recovery
4)　　RRM
5)　　Beam management,

where CSI reports corresponding to tracking (TRS) have the highest priority for multiplexing with SR and/or HARQ feedback within the DRX inactive period of the base station, and CSI reports corresponding to beam management have the lowest priority for multiplexing with SR and/or HARQ feedback within the DRX inactive period of the base station. A CSI report comprising A-CSI for data transmission and scheduling may be configured to be 'disabled' (e.g. by signalling from the base station 5) during the DRX inactive period of the base station 5.

Overlap of PUCCH and Cell DRX Inactive Period
When the base station is configured to have DRX inactive and DRX active periods, higher layer signalling may be used to configure the UE 3 not to transmit using PUCCH during the DRX inactive period of the base station 5. However, the configured PUCCH resources might not necessarily align with the boundaries of the DRX inactive period and the DRX active period. Configured PUCCH resources may also overlap with each other. In this case, multiplexing of high priority and low priority data, such as SR and HARQ-ACK, may be performed on the high priority PUCCH and the transmission on low priority PUCCH may be cancelled. If a PUCCH within the DRX active period of the base station overlaps in the time domain with a PUCCH for a disabled CSI in the DRX inactive period of the base station 5, then the UE 3 does not perform the transmission in the DRX inactive period and does not perform UCI multiplexing. Alternatively, if a PUCCH in the cell DRX inactive period ends before the overlapping PUCCH of the cell DRX active period, then the UE 3 may first perform UCI multiplexing, and the transmission can take place during the cell DRX active period.

Short Cell DRX Cycle
As described above, a SR may be transmitted during the DRX inactive period of the base station. For example, the UE 3 may determine to transmit the SR when the SR corresponds to high priority uplink data. Following the transmission of the SR, exchanges of PDSCH, PUSCH and control information may be needed between the network and the UE 3, which may normally require the base station 5 to be in the DRX active state. One option is for a configured grant CG to be configured for use only during the DRX inactive period of the base station. However, the inventors have realised that there are other advantageous methods in which UL transmissions (e.g. CG) from the UE 3 can be configured during the DRX inactive period of the base station 5.

　　Upon receiving particular UCI (e.g. including SR corresponding to high priority uplink data, a measurement report for mobility, or beam failure related information) during the DRX inactive period, the base station 5 may be configured to 'wake up' and use a shorter DRX cycle. As described above with reference to Fig. 9, the ON duration of a DRX cycle (i.e. the DRX active period), t1, need not necessarily be of a fixed time duration, and can be different from the duration of the OFF duration (e.g. the DRX inactive period) which can also have a variable duration.

　　Fig. 18 shows an example in which the base station 5 may have a long cell DRX configuration or a short cell DRX configuration. Advantageously, the base station 5 may determine to use the short cell DRX configuration in a period in which the base station 5 would normally be in the DRX inactive period of the long cell DRX configuration, for example based on a determination that high priority uplink transmissions are to be received.

　　Fig. 18 also shows time occasions in which an SR occasion is available but not used, time occasions in which an SR occasion is available and used, and time occasions in which CG resources are available. As shown in Fig 18. the base station 5 is configured to activate the short cell DRX configuration and to schedule the CG resources during the DRX active periods of the short cell DRX configuration. The DRX active periods of the short DRX cycle (or that the base station 5 has determined to use the short cell DRX configuration) need not be known by all UEs 3 in a cell of the base station 5. As illustrated in Fig. 18 the base station 5 may transmit an indication (e.g. during the DRX inactive period of the long cell DRX configuration) to one or more UEs 3 that the base station 5 has determined to use the short cell DRX configuration. The notification may be transmitted to UEs 3 that are to transmit particular UCI (e.g. corresponding to high priority transmissions).

　　In a first option, after the UE 3 transmits an initial UL signal (e.g. SR), the base station 5 transmits an acknowledgement or other suitable type of transmission that indicates that the base station 5 has determined to use the short cell DRX configuration. The signaling may be UE specific, or could be an indication that is transmitted to a group of UEs 3 (group-UE based control signalling), or alternatively could be provided within UL grant for a UE 3.
In a second option, after the UE 3 transmits the initial UL signal (e.g. SR), the UE 3 may be configured to assume (e.g. automatically determine) that the base station 5 will use the short cell DRX configuration, and transmit subsequent uplink transmissions accordingly.

　　In a third option, an L1/L2 indication may be provided to the UE 3 by the network, indicating that the DRX inactive period of the long cell DRX configuration is disabled for a particular time period. After receiving the indication, the UE 3 then performs regular UL/DL transmissions as would be performed when the base station 5 is in the DRX/DTX active state.

　　During the DRX active periods of the short cell DRX configuration, configured UL resources that fit within the DRX active periods can be used. The method may comprise lifting or disabling masking. The base station 5 may provide an indication to the UE 3 within activation signalling for the short DRX configuration (signalling that the base station 5 is to use the short cell DRX configuration), or within an RRC configuration, of which UL signal channels are to be activated (for transmission) during the short DRX periods.

　　Optionally, or alternatively, a short DTX cycle may be configured and applied during DTX inactive periods of normal cell DTX. This is similar to the case of DRX described above, except that the shorter cycles are applied for DTX operation rather than DRX operation. During cell DRX inactive, UL transmissions may be performed using dynamic scheduling, and therefore with shorter DTX cycles the base station 5 would be able to transmit UL grants via DCI to a UE 3 even during normal cell DTX inactive periods, which would allow subsequent PUSCH transmissions from the UE 3 even during the cell DRX inactive state. The signalling for indicating the start or activation of the short cell DTX state can be the same as for the signalling for the start of activation of the short cell DRX state described above. However, it will be appreciated that signalling need not be exactly the same, and that a first set of signalling can be used for indicating the start or activation of the short cell DTX state, and a similar but separate set of signalling can be used for indicating the start or activation of the short cell DRX state. During the active period of the short DTX cycle, the UE 3 is configured to monitor DCI identified by C-RNTI, to receive any UL grant from the base station.

User Equipment
　　Fig. 19 is a schematic block diagram illustrating the main components of a UE 3 as shown in Fig. 1.
　　As shown, the UE 3 has a transceiver circuit 310 that is operable to transmit signals to and to receive signals from a base station 5 via one or more antenna 330 (e.g., comprising one or more antenna elements). The UE 3 has a controller 370 to control the operation of the UE 3. The controller 370 is associated with a memory 390 and is coupled to the transceiver circuit 310. 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 350, 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 390 and/or may be downloaded via the communication system 1 or from a removable data storage device (RMD), for example.

　　The controller 370 is configured to control overall operation of the UE 3 by, in this example, program instructions or software instructions stored within memory 390. As shown, these software instructions include, among other things, an operating system 410, a communications control module 430, a UCI module 450, a HARQ module 470 and an NES module 490.

　　The communications control module 430 is operable to control the communication between the UE 3 and one or more its serving base stations 5 (and other communication devices connected to the base station 5, such as further UEs and/or core network nodes). The communications control module 430 is configured for the overall handling uplink communications via associated uplink channels (e.g. via a physical uplink control channel (PUCCH), random access channel (RACH), and/or a physical uplink shared channel (PUSCH)) including both dynamic and semi-static signalling (e.g., SRS). The communications control module 430 is also configured for the overall handling of receipt of downlink communications via associated downlink channels (e.g. via a physical downlink control channel (PDCCH) and/or a physical downlink shared channel (PDSCH)) including both dynamic and semi-static signalling (e.g., CSI-RS). The communications control module 430 is responsible, for example: for determining where to monitor for downlink control information (e.g., the location of CSSs / USSs, CORESETs, and associated PDCCH candidates to monitor); 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 SBFD communication, or the like); for determining which one or more bandwidth parts are configured for the UE 3; for determining how uplink transmissions should be encoded; for applying any SBFD specific communication configurations appropriately; and the like. The UCI module 450 may be configured to control communications in accordance with any of the methods described above (for example, transmit UCI based on control information received from the base station). The HARQ module 470 may be configured to control communications to transmit HARQ feedback in accordance with any of the methods described above. Similarly, the NES module 490 may control communications to perform any of the network energy saving methods described above (e.g. by controlling the UE 3 to enter a DRX or DTX state).

Base Station
　　Fig. 20 is a schematic block diagram illustrating the main components of the base station 5 for the communication system 1 shown in Fig. 1. As shown, the base station 5 has a transceiver circuit 510 for transmitting signals to and for receiving signals from the communication devices (such as UEs 3) via one or more antenna 530 (e.g. a single or multi-panel antenna array / massive antenna), and a core network interface 550 (e.g. comprising the N2, N3 and other reference points/interfaces) for transmitting signals to and for receiving signals from network nodes in the core network 7. Although not shown, the base station 5 may also be coupled to other base stations via an appropriate interface (e.g. the so-called 'Xn' interface in NR). The base station 5 has a controller 570 to control the operation of the base station 5. The controller 570 is associated with a memory 590. Software may be pre-installed in the memory 590 and/or may be downloaded via the communications network 1 or from a removable data storage device (RMD), for example. The controller 570 is configured to control the overall operation of the base station 5 by, in this example, program instructions or software instructions stored within memory 590.
As shown, these software instructions include, among other things, an operating system 610, a communications control module 630, and an NES module 650.

　　The communications control module 630 is operable to control the communication between the base station 5 and UEs 3 and other network entities that are connected to the base station 5. The communications control module 630 is configured for the overall control of the reception and decoding of uplink communications, via associated uplink channels (e.g. via a physical uplink control channel (PUCCH), a random-access channel (RACH), and/or a physical uplink shared channel (PUSCH)) including both dynamic and semi-static signalling (e.g., SRS). The communications control module 630 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). The communications control module 630 is responsible for managing full duplex (e.g., SBFD) communication including, where appropriate, the segregation of UL and DL communication via different physical antenna elements. The communications control module 630 is responsible, for example: for determining where to configure the UE 3 to monitor for downlink control information (e.g., the location of CSSs / USSs, CORESETs, and associated PDCCH candidates to monitor); for determining the resources to be scheduled for UE transmission/reception of UL/DL communications (including interleaved resources and resources subject to frequency hopping); for managing frequency hopping at the base station side; for configuring slots/symbols appropriately (e.g., for UL, DL or SBFD communication, or the like); for configuring one or more bandwidth parts for the UE 3; for providing related configuration signalling to the UE 3; and the like. The communications control module 630 may be configured to control communications in accordance with any of the methods described above. The NES module 650 may be configured to control communications in accordance with any of the methods described above (e.g. to control the base station 5 to enter a DTX or DRX state, or to transmit control information for configuring time or frequency resources for uplink transmissions by the UE 3 during a DTX or DRX period of the base station 5).

Core Network Node/Function
Fig. 21 is a block diagram illustrating the main components of a core network node or function, such as the AMF, CPF, the UPF, the SMF or OAM. As shown, the core network function includes a transceiver circuit 710 which is operable to transmit signals to and to receive signals from other nodes (including the UE 3, the base station 5, and other core network nodes) via a network interface 720. A controller 730 controls the operation of the core network function in accordance with software stored in a memory 740. The software may be pre-installed in the memory 740 and/or may be downloaded via the communication system 1 or from a removable data storage device (RMD), for example. The software includes, among other things, an operating system 750, and a communications control module 760.

　　The communications control module 760 is responsible for handling (generating/sending/ receiving) signalling between the core network function and other nodes, such as the UE 3, the base station 5, and other core network nodes. The communications control module 760 may be configured to perform control of communications in accordance with any of the methods described above.

Modifications and Alternatives
As those skilled in the art will appreciate, a number of modifications and alternatives can be made to the above example embodiments whilst still benefiting from the disclosure embodied therein.
It will be appreciated, for example, that whilst cellular communication generation (2G, 3G, 4G, 5G, 6G etc.) specific terminology may be used, in the interests of clarity, to refer to specific communication entities, the technical features described for a given entity are not limited to devices of that specific communication generation. The technical features may be implemented in any functionally equivalent communication entity regardless of any differences in the terminology used to refer to them.

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

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

　　Each controller may comprise any suitable form of processing circuitry including (but not limited to), for example: one or more hardware implemented computer processors; microprocessors; central processing units (CPUs); arithmetic logic units (ALUs); input/output (IO) circuits; internal memories / caches (program and/or data); processing registers; communication buses (e.g. control, data and/or address buses); direct memory access (DMA) functions; hardware or software implemented counters, pointers and/or timers; and/or the like. Various other modifications will be apparent to those skilled in the art and will not be described in further detail here.
The base station may comprise a 'distributed' base station having a central unit 'CU' and one or more separate distributed units (DUs).
The User Equipment (or "UE", "mobile station", "mobile device" or "wireless device") in the present disclosure is an entity connected to a network via a wireless interface.

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

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

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

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

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

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

　　A UE may, for example, be an electronic lamp, a luminaire, a measuring instrument, an 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.

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

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

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

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

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

　　Further, the above-described UE categories are merely examples of applications of the technical ideas and example embodiments described in the present document. Needless to say, these technical ideas and example embodiments are not limited to the above-described UE and various modifications can be made thereto.
Various other modifications will be apparent to those skilled in the art and will not be described in further detail here.

This application is based upon and claims the benefit of priority from UK patent application No. 2307044.4, filed on May 11, 2023, the disclosure of which is incorporated herein in its entirety by reference.

　　The whole or part of the exemplary embodiments disclosed above can be described as, but not limited to, the following supplementary notes.
　　(Supplementary note 1)
　　A method performed by an access network node, the method comprising:
　　transmitting, to a user equipment, UE, an indication of at least one communication resource for use by the UE for an uplink transmission; and
　　receiving, from the UE, the uplink transmission transmitted using the at least one communication resource;
　　wherein the at least one communication resource overlaps in the time domain with a first period in which the access network node operates in a discontinuous reception, DRX, inactive mode; and
　　wherein the access network node selects the at least one communication resource so that the uplink transmission at least partially overlaps with another uplink transmission in the time domain during the first period.
　　(Supplementary note 2)
　　The method according to supplementary note 1, wherein the uplink transmission is a physical uplink control channel, PUCCH, transmission, and the at least one communication resource comprises time and frequency resources for the PUCCH transmission.
　　(Supplementary note 3)
　　The method according to supplementary note 2, wherein the uplink transmission comprises uplink control information, UCI, transmitted using the PUCCH.
　　(Supplementary note 4)
　　The method according to any preceding supplementary note, wherein the uplink transmission comprises a scheduling request, SR, channel state information, CSI, report, or hybrid automatic repeat request, HARQ, feedback.
　　(Supplementary note 5)
　　The method according to supplementary note 4, wherein the uplink transmission comprises a SR or CSI, and the SR or CSI is associated with an uplink transmission for a beam management procedure, a radio link failure procedure, a beam failure procedure, or a handover procedure.
　　(Supplementary note 6)
　　The method according to any preceding supplementary note, wherein the indication of the at least one communication resource comprises an indication of a periodicity for the uplink transmission.
　　(Supplementary note 7)
　　The method according to any preceding supplementary note,
　　wherein the access network node operates in a DRX active mode during a second period, different from the first period, and
　　wherein the indication of at least one communication resource comprises an indication of a difference between the at least one communication resource and a communication resource used for the uplink transmission during the second period.
　　(Supplementary note 8)
　　The method according to supplementary note 7, wherein the indication of at least one communication resource comprises an indication of a difference in periodicity or time offset for the uplink transmission.
　　(Supplementary note 9)
　　The method according to supplementary note 7 or 8, wherein the method further comprises transmitting, to the UE, an indication that a configuration for an uplink transmission for use in the second period is to be disabled during the first period.
　　(Supplementary note 10)
　　The method according to any preceding supplementary note,
　　wherein the uplink transmission comprises HARQ feedback for a downlink transmission; and
　　wherein the indication of at least one communication resource for use by the UE for the uplink transmission comprises an indication of a time period between reception of the downlink transmission at the UE and transmission of the HARQ feedback.
　　(Supplementary note 11)
　　The method according to supplementary note 10, wherein the time period between reception of the downlink transmission at the UE and transmission of the HARQ feedback is larger than 15 slots.
　　(Supplementary note 12)
　　The method according to supplementary note 10 or 11, wherein the time period between reception of the downlink transmission at the UE and transmission of the HARQ feedback during the first period is larger than a time period between reception of the downlink transmission at the UE and transmission of the HARQ feedback that is supported when the access network node is operating in a DRX active mode.
　　(Supplementary note 13)
　　The method according to any preceding supplementary note, wherein the another uplink transmission comprises uplink control information transmitted by another UE.
　　(Supplementary note 14)
　　The method according to any one of supplementary notes 1 to 12, wherein the another uplink transmission is transmitted by the UE.
　　(Supplementary note 15)
　　The method according to supplementary note 14, wherein the uplink transmission comprises HARQ feedback associated with a first downlink transmission, and the another uplink transmission comprises HARQ feedback that is associated with a second downlink transmission.
　　(Supplementary note 16)
　　The method according to any preceding supplementary note, wherein the method comprises transmitting, to the UE, an indication of one or more PUCCH configurations for use by the UE for uplink transmissions in the first period but not in the second period.
　　(Supplementary note 17)
　　The method according to any preceding supplementary note, wherein the method comprises transmitting, to the UE, an indication of a configuration for transmission of a physical uplink shared channel, PUSCH, during the first period that is different from a configuration for transmission of the PUSCH during the second period.
　　(Supplementary note 18)
　　The method according to any preceding supplementary note, wherein the method comprises transmitting, to the UE, information indicating whether transmission of a scheduling request is allowed during the first period.
　　(Supplementary note 19)
　　The method according to supplementary note 18, wherein the information indicating whether transmission of a scheduling request is allowed during the first period indicates whether transmission of the scheduling request is allowed during the first period per scheduling request or per logical channel.
　　(Supplementary note 20)
　　A method performed by a user equipment, UE, the method comprising:
　　receiving, from an access network node, an indication of at least one communication resource for use by the UE for an uplink transmission; and
　　transmitting, to the access network node, the uplink transmission using the at least one communication resource;
　　wherein the at least one communication resource overlaps in the time domain with a first period in which the access network node operates in a discontinuous reception, DRX, inactive mode; and
　　wherein the at least one communication resource is selected so that the uplink transmission at least partially overlaps with another uplink transmission in the time domain during the first period.
　　(Supplementary note 21)
　　The method according to supplementary note 20, wherein the uplink transmission is a PUCCH transmission, and the at least one communication resource comprises time and frequency resources for the PUCCH transmission.
　　(Supplementary note 22)
　　The method according to supplementary note 21, wherein the uplink transmission comprises uplink control information, UCI, transmitted using the PUCCH.
　　(Supplementary note 23)
　　The method according to any one of supplementary notes 20 to 22, wherein the uplink transmission comprises a scheduling request, SR, channel state information, CSI, report, or hybrid automatic repeat request, HARQ, feedback.
　　(Supplementary note 24)
　　The method according to supplementary note 23, wherein the wherein the uplink transmission comprises a SR or CSI, and the SR or CSI is associated with an uplink transmission for a beam management procedure, a radio link failure procedure, a beam failure procedure, or a handover procedure.
　　(Supplementary note 25)
　　The method according any one of supplementary notes 20 to 24, wherein the indication of the at least one communication resource comprises an indication of a periodicity for the uplink transmission.
　　(Supplementary note 26)
　　The method according to any one of supplementary notes 20 to 25,
　　wherein the access network node operates in a DRX active mode during a second period, different from the first period, and
　　wherein the indication of at least one communication resource comprises an indication of a difference between the at least one communication resource and a communication resource used for the uplink transmission during the second period.
　　(Supplementary note 27)
　　The method according to supplementary note 26, wherein the indication of at least one communication resource comprises an indication of a difference in periodicity or time offset for the uplink transmission.
　　(Supplementary note 28)
　　The method according to supplementary note 26 or 27, wherein the method further comprises receiving, from the access network node, an indication that a configuration for an uplink transmission for use in the second period is to be disabled during the first period.
　　(Supplementary note 29)
　　The method according to any one of supplementary notes 20 to 28,
　　wherein the uplink transmission comprises HARQ feedback for a downlink transmission; and
　　wherein the indication of at least one communication resource for use by the UE for the uplink transmission comprises an indication of a time period between reception of the downlink transmission at the UE and transmission of the HARQ feedback.
　　(Supplementary note 30)
　　The method according to supplementary note 29, wherein the time period between reception of the downlink transmission at the UE and transmission of the HARQ feedback is larger than 15 slots.
　　(Supplementary note 31)
　　The method according to supplementary note 29 or 30, wherein the time period between reception of the downlink transmission at the UE and transmission of the HARQ feedback during the first period is larger than a time period between reception of the downlink transmission at the UE and transmission of the HARQ feedback that is supported when the access network node is operating in a DRX active mode.
　　(Supplementary note 32)
　　The method according to any one of supplementary notes 20 to 31, wherein the another uplink transmission comprises uplink control information transmitted by another UE.
　　(Supplementary note 33)
　　The method according to any one of supplementary notes 20 to 32, wherein the another uplink transmission is transmitted by the UE.
　　(Supplementary note 34)
　　The method according to supplementary note 33, wherein the uplink transmission comprises HARQ feedback associated with a first downlink transmission, and the another uplink transmission comprises HARQ feedback that is associated with a second downlink transmission.
　　(Supplementary note 35)
　　The method according to any one of supplementary notes 20 to 34, wherein the method comprises receiving, from the access network node, an indication of one or PUCCH configurations for use by the UE for uplink transmissions in the first period but not in the second period.
　　(Supplementary note 36)
　　The method according to any one of supplementary notes 20 to 35, wherein the method comprises receiving, from the access network node, an indication of a configuration for transmission of a physical uplink shared channel, PUSCH, during the first period that is different from a configuration for transmission of the PUSCH during the second period.
　　(Supplementary note 37)
　　The method according to any one of supplementary notes 20 to 36, wherein the method comprises receiving, from the access network node, information indicating whether transmission of a scheduling request is allowed during the first period.
　　(Supplementary note 38)
　　The method according to supplementary note 37, wherein the information indicating whether transmission of a scheduling request is allowed during the first period indicates whether transmission of the scheduling request is allowed during the first period per scheduling request or per logical channel.
　　(Supplementary note 39)
　　The method according to any one of supplementary notes 20 to 38, wherein the method further comprises:
　　transmitting a scheduling request to the access network node when the access network node is operating in a discontinuous transmission, DTX, inactive mode; and
　　monitoring for transmission of downlink control information corresponding to the scheduling request during a period assigned for operation of the access network node in the DTX inactive mode.
　　(Supplementary note 40)
　　A method performed by a user equipment, UE, the method comprising:
　　determining to initiate a random access procedure comprising transmission on a physical random access channel, PRACH, to an access network node;
　　determining whether transmission on the PRACH is allowed during a first period in which the access network node operates in a discontinuous reception, DRX, inactive mode;
　　if it is determined that transmission on the PRACH is not allowed during the first period, then delaying transmission of the PRACH until the access network node is operating in a DRX active mode; and
　　if it is determined that transmission on the PRACH is allowed during the first period, then transmitting the PRACH to the access network node during the first period.
　　(Supplementary note 41)
.　　The method according to supplementary note 40, wherein the determination to initiate the random access procedure is made before the first period, when the access network node is operating in a DRX active mode, but a first time occasion available for transmission of the PRACH overlaps with the first period.
　　(Supplementary note 42)
　　The method according to supplementary note 40, wherein the determination to initiate the random access procedure is made during the first period.
　　(Supplementary note 43)
　　A method performed by an access network node, the method comprising:
　　receiving a scheduling request from a UE during a first period for operation of the access network node in a discontinuous reception, DRX, inactive mode using a first DRX configuration; and
　　determining, based on the scheduling request, to use a second DRX configuration that defines a set of second periods in which the access network node is to operate in a DRX inactive mode and a set of third periods in which the access network node is to operate in a DRX active mode;
　　wherein the second periods and the third periods are shorter than the first period.
　　(Supplementary note 44)
　　The method according to supplementary note 43, wherein the determination to use the second DRX configuration is based on an uplink transmission priority associated with the scheduling request.
　　(Supplementary note 45)
　　The method according to supplementary note 43 or 44, wherein the method further comprises configuring a set of configured grant resources for the UE to overlap in the time domain with the third periods.
　　(Supplementary note 46)
　　The method according to any one of supplementary notes 43 to 45, wherein the set of second periods and the set of third periods are arranged within the first period.
　　(Supplementary note 47)
　　The method according to any one of supplementary notes 43 to 46, wherein the method further comprises transmitting an indication to the UE that an uplink transmission corresponding to the scheduling request is to be transmitted during the first period.
　　(Supplementary note 48)
　　The method according to any one of supplementary notes 43 to 47, wherein the method further comprises transmitting an indication to the UE that the access network node is to use the second DRX configuration.
　　(Supplementary note 49)
　　A method performed by a user equipment, UE, the method comprising:
　　transmitting a scheduling request to an access network node during a first period in which the access network node is operating in discontinuous reception, DRX, inactive mode using a first DRX configuration;
　　receiving, from the access network node, an indication that an uplink transmission corresponding to the scheduling request is to be transmitted during the first period; and
　　transmitting the uplink transmission to the access network node during the first period.
　　(Supplementary note 50)
　　An access network node comprising:
　　means for transmitting, to a user equipment, UE, an indication of at least one communication resource for use by the UE for an uplink transmission; and
　　means for receiving, from the UE, the uplink transmission transmitted using the at least one communication resource;
　　wherein the at least one communication resource overlaps in the time domain with a first period in which the access network node operates in a discontinuous reception, DRX, inactive mode; and
　　wherein the access network node is configured to select the at least one communication resource so that the uplink transmission at least partially overlaps with another uplink transmission in the time domain during the first period.
　　(Supplementary note 51)
　　A user equipment, UE, comprising:
　　means for receiving, from an access network node, an indication of at least one communication resource for use by the UE for an uplink transmission; and
　　means for transmitting, to the access network node, the uplink transmission using the at least one communication resource;
　　wherein the at least one communication resource overlaps in the time domain with a first period in which the access network node operates in a discontinuous reception, DRX, inactive mode; and
　　wherein the at least one communication resource is selected so that the uplink transmission at least partially overlaps with another uplink transmission in the time domain during the first period.
　　(Supplementary note 52)
　　A user equipment, UE, comprising:
　　means for determining to initiate a random access procedure comprising transmission on a physical random access channel, PRACH, to an access network node; and
　　means for determining whether transmission on the PRACH is allowed during a first period in which the access network node operates in a discontinuous reception, DRX, inactive mode;
　　wherein the UE is configured for:
　　if it is determined that transmission on the PRACH is not allowed during the first period, delaying transmission of the PRACH until the access network node is operating in a DRX active mode; and
　　if it is determined that transmission on the PRACH is allowed during the first period, transmitting the PRACH to the access network node during the first period.
　　(Supplementary note 53)
　　An access network node comprising:
　　means for receiving a scheduling request from a UE during a first period for operation of the access network node in a discontinuous reception, DRX, inactive mode using a first DRX configuration; and
　　means for determining, based on the scheduling request, to use a second DRX configuration that defines a set of second periods in which the access network node is to operate in a DRX inactive mode and a set of third periods in which the access network node is to operate in a DRX active mode;
　　wherein the second periods and the third periods are shorter than the first period.
　　(Supplementary note 54)
　　A user equipment, UE, comprising:
　　means for transmitting a scheduling request to an access network node during a first period in which the access network node is operating in discontinuous reception, DRX, inactive mode using a first DRX configuration;
　　means for receiving, from the access network node, an indication that an uplink transmission corresponding to the scheduling request is to be transmitted during the first period; and
　　means for transmitting the uplink transmission to the access network node during the first period.

3-1, 3-2, 3-3　　User Equipment (UE)
5　　Base station, Radio Access Network (RAN) node
7　　Core Network
9　　Cell
10　　Control Plane Functions (CPF)
11　　User Plane Functions (UPF)
50　　DU
60　　CU
310　　Transceiver circuit
330　　Antenna
350　　User Interface
370　　Controller
390　　Memory
410　　Operating System
430　　Communications Control module
450　　UCI module
470　　HARQ module
490　　NES module
451　　Transceiver Circuit
453　　DU-RU interface
454　　CU interface
457　　Controller
459　　Memory
461　　Operating System
463　　Communications Control Module
465　　 F1 module
468　　DU-RU module
472　　DU management module
473　　UE profile management module
475　　Mobility module
530　　Antenna
550　　Core Network Interface
570　　Controller
590　　memory
551　　Transceiver circuit
554　　DU interface
555　　Core network interface
557　　Controller
559　　Memory
561　　operating system
563　　communications control module
565　　F1 module
566　　E1 module
568　　N2 module
569　　N3 module
571　　CU-UP management module
572　　CU-CP management module
573　　UE profile management module
575　　Mobility module
610　　Operating System
630　　Communications control module
650　　NES module
710　　Transceiver Circuit
720　　Network Interface
730　　Controller
740　　Memory
750　　Operating system
760　　Communications control module

Claims

　　A method performed by a user equipment (UE), the method comprising:
　　receiving, from an access network node, configuration information for transmitting uplink control information,
　　wherein the configuration information indicates first resources in a cell discontinuous reception (DRX) / discontinuous transmission (DTX) inactive state of the access network node, and
　　wherein the first resources include a part of second resources in a cell DRX / DTX active state of the access network node; and
　　transmitting, to the access network node, the uplink control information based on the configuration information.
　　The method according to claim 1, wherein
　　the configuration information includes a parameter indicating a value of a periodicity or an offset for determining occasions of the first resources.
　　The method according to claim 2, wherein
　　the UE is configured such that the transmission of the uplink control information is disabled on an occasion of the first resources unless the parameter indicates the value of the periodicity or the offset for determining the occasion.
　　The method according to any one of claims 1 to 3, wherein
　　the configuration information includes first information indicating whether transmission of the uplink control information is enabled or disabled for each type of the uplink control information.
　　The method according to claim 4, wherein
　　the UE is configured such that the transmission of the uplink control information is disabled unless the first information indicates that the transmission of the uplink control information is enabled.
　　The method according to any one of claims 1 to 5, wherein
　　the configuration information includes delta information indicating a difference between the first resources and the second resources.
　　The method according to any one of claims 1 to 6, wherein
　　a plurality of uplink control information are bundled and transmitted using one or more of the first resources.
　　The method according to claim 7, wherein
　　the plurality of uplink control information are transmitted from the UE.
　　The method according to claim 7, wherein
　　one of the plurality of the uplink control information is transmitted from another UE.
　　The method according to any one of claims 1 to 9, wherein
　　the uplink control information includes Hybrid Automatic Repeat Request (HARQ) feedback for a downlink transmission, and
　　the configuration information includes delay information indicating a period between reception of the downlink transmission by the UE and transmission of the HARQ feedback for the cell DRX / DTX inactive state.
　　The method according to claim 10, wherein
　　the period is larger than a period between reception of the downlink transmission by the UE and transmission of the HARQ feedback for the cell DRX / DTX active state.
　　The method according to claim 11, wherein
　　the period is derived based on the period between reception of the downlink transmission by the UE and transmission of the HARQ feedback for the cell DRX / DTX active state and an offset.
　　The method according to claim 12, wherein
　　the offset has a UE specific value.
　　The method according to any one of claims 10 to 13, wherein
　　the period is larger than 15 slots.
　　The method according to any one of claims 1 to 14, wherein
　　the configuration information includes second information indicating whether a respective resource is disabled for transmitting the uplink control information, for each resource in the second resources.
　　The method according to claim 15, wherein
　　the second information indicates that at least one resource whose payload size is higher than a specific value is disabled for transmitting the uplink control information.
　　The method according to claim 15 or 16, further comprising:
　　initiating a random access procedure during the cell DRX / DTX inactive state, in a case where a resource for transmitting the uplink control information is disabled.
　　The method according to any one of claims 1 to 17, wherein
　　the first resources include specific resources not included in the second resources, and
　　the specific resources are only used during the cell DRX / DTX inactive state.
　　The method according to any one of claims 1 to 18, wherein
　　the uplink control information includes at least one of:
　　　　a scheduling request (SR),
　　　　channel state information (CSI) report, or
　　　　a hybrid automatic repeat request (HARQ) feedback.
　　The method according to any one of claims 1 to 19, further comprising:
　　receiving third information indicating whether transmission of a scheduling request is allowed during the cell DRX / DTX inactive state.
　　The method according to claim 20, wherein
　　the third information indicates whether the transmission of the scheduling request is allowed during the cell DRX / DTX inactive state per scheduling request or per logical channel.
　　The method according to any one of claims 1 to 21, wherein
　　the first resources are for at least one of:
　　　　Physical Uplink Control Channel (PUCCH), or
　　　　Physical Uplink Shared Channel (PUSCH).
　　A method performed by a user equipment (UE), the method comprising:
　　receiving, from an access network node, information indicating whether transmitting a scheduling request is allowed during a cell discontinuous reception (DRX) / discontinuous transmission (DTX) inactive state; and
　　determining whether to initiate a random access procedure for transmitting the scheduling request based on the information.
　　The method according to claim 23, wherein
　　the information is included in at least one of:
　　　　configuration information of a scheduling request,
　　　　configuration information of a logical channel, or
　　　　configuration information of a measurement by the UE.
　　The method according to claim 23 or 24, further comprising:
　　in a case where the UE determines to initiate the random access procedure, monitoring downlink transmission from the access network node after transmitting the scheduling request.
　　The method according to claim 24 or 25, wherein
　　in a case where there are no resources for transmitting the scheduling request present, the determining is performed by at least one of:
　　　　determining not to initiate the random access procedure regardless of the information,
　　　　determining to initiate the random access procedure based on the information, or
　　　　determining to delay to initiate the random access procedure until the cell DRX / DTX inactivity state ends.
　　A method performed by a user equipment (UE), the method comprising:
　　transmitting a scheduling request to an access network node during a discontinuous reception (DRX) / discontinuous transmission (DTX) inactive state of the access network node;
　　receiving, from the access network node, information indicating that an uplink transmission corresponding to the scheduling request is to be transmitted during a short DRX/ DTX period which is shorter than a period of the cell DRX/DTX inactive state; and
　　transmitting the uplink transmission to the access network node during the short DRX/ DTX period.
　　A method performed by an access network node, the method comprising:
　　transmitting, to a user equipment (UE), configuration information for transmitting uplink control information,
　　wherein the configuration information indicates first resources in a cell discontinuous reception (DRX) / discontinuous transmission (DTX) inactive state of the access network node, and
　　wherein the first resources include a part of second resources in a cell DRX / DTX active state of the access network node; and
　　receiving, from the UE, the uplink control information based on the configuration information.
　　A method performed by an access network node, the method comprising:
　　transmitting, to a user equipment (UE), information indicating whether transmitting a scheduling request is allowed during a cell discontinuous reception (DRX) / discontinuous transmission (DTX) inactive state, wherein
　　the information causes the UE to determine whether to initiate a random access procedure for transmitting the scheduling request based on the information.
　　A method performed by an access network node, the method comprising:
　　receiving a scheduling request from a user equipment (UE) during a cell discontinuous reception, (DRX) / discontinuous transmission (DTX) inactive state of the access network node;
　　transmitting, to the UE, information indicating that an uplink transmission corresponding to the scheduling request is to be transmitted during a short DRX/ DTX period which is shorter than a period of the cell DRX/DTX inactive state; and
　　receiving the uplink transmission from the UE during the short DRX/ DTX period.
　　A user equipment (UE) comprising:
　　means for receiving, from an access network node, configuration information for transmitting uplink control information,
　　wherein the configuration information indicates first resources in a cell discontinuous reception (DRX) / discontinuous transmission (DTX) inactive state of the access network node, and
　　wherein the first resources include a part of second resources in a cell DRX / DTX active state of the access network node; and
　　means for transmitting, to the access network node, the uplink control information based on the configuration information.
　　A user equipment (UE) comprising:
　　means for receiving, from an access network node, information indicating whether transmitting a scheduling request is allowed during a cell discontinuous reception (DRX) / discontinuous transmission (DTX) inactive state; and
　　means for determining whether to initiate a random access procedure for transmitting the scheduling request based on the information.
　　A user equipment (UE) comprising:
　　means for transmitting a scheduling request to an access network node during a discontinuous reception (DRX) / discontinuous transmission (DTX) inactive state of the access network node;
　　means for receiving, from the access network node, information indicating that an uplink transmission corresponding to the scheduling request is to be transmitted during a short DRX/ DTX period which is shorter than a period of the cell DRX/DTX inactive state; and
　　means for transmitting the uplink transmission to the access network node during the short DRX/ DTX period.
　　An access network node comprising:
　　means for transmitting, to a user equipment (UE), configuration information for transmitting uplink control information,
　　wherein the configuration information indicates first resources in a cell discontinuous reception (DRX) / discontinuous transmission (DTX) inactive state of the access network node, and
　　wherein the first resources include a part of second resources in a cell DRX / DTX active state of the access network node; and
　　means for receiving, from the UE, the uplink control information based on the configuration information.
　　An access network node comprising:
　　means for transmitting, to a user equipment (UE), information indicating whether transmitting a scheduling request is allowed during a cell discontinuous reception (DRX) / discontinuous transmission (DTX) inactive state, wherein
　　the information causes the UE to determine whether to initiate a random access procedure for transmitting the scheduling request based on the information.
　　An access network node comprising:
　　means for receiving a scheduling request from a user equipment (UE) during a cell discontinuous reception, (DRX) / discontinuous transmission (DTX) inactive state of the access network node;
　　means for transmitting, to the UE, information indicating that an uplink transmission corresponding to the scheduling request is to be transmitted during a short DRX/ DTX period which is shorter than a period of the cell DRX/DTX inactive state; and
　　means for receiving the uplink transmission from the UE during the short DRX/ DTX period.