Cell DTX and / or cell DRX

Abstract

The user equipment (UE) handles discontinuous transmission and / or reception (CDTR) by, in response to receiving a first message (e.g. RRCRelease with suspendconfig) indicating that the UE is required

Description

BACKGROUND Field Certain examples of the present disclosure provide one or more techniques for handling Cell DRX and / or Cell DRX states in a network. For example, certain examples provide one or more techniques for synchronising Cell DRX and / or Cell DTX states between a UE and a base station (or associated cell) when the UE enters and exits an RRC inactive state in a 3rd Generation Partnership Project (3GPP) 5th Generation (5G) New Radio (NR) network. Description of the Related Art Overview of Release 18 Network energy savings Network energy savings (NES) is Release 18 Work Item to introduce methods to allow for energy savings for a network [1], rather than UEs. This is because a significant amount of OPEX for operators is spent on energy costs. The work item followed a Study Item where a base station energy consumption model was developed and different methods for energy savings were evaluated. The Study Item resulted in a Technical Report 38.864 [2], The objective of the work item are: - Specify SSB-less SCell operation. o This allows a network to de-activate the SSBs on cells other than the PCell in a cell that operates Carrier Aggregation. - Specify enhancement on cell DTX / DRX mechanism. o DRX is a legacy feature that allows a UE to power down monitoring to save UE power consumption. o Cell DTX / DRX allows a network to power down either transmission or reception operation. This is done by configuring a UE to not monitor or to not transmit in certain opportunities. - Specify techniques in spatial and power domain. o Enhancements on CSI and beam management-related procedures. o Enhancements on CSI-related procedures to enable efficient adaptation of power offset values between PDSCH and CSI-RS. - Specify mechanisms to prevent legacy UEs from camping on cells using Rel-18 NES. - Specify CHO procedure enhancements for cells in NES mode. - Inter-node beam activation. Overview of Cell DTX / DRX The Cell DTX / DRX is introduced to allow for a network to reduce power consumption by partly turning off transmit and receive functionality. The Cell DTX and DRX are dedicatedly configured per UE in RRC CONNECTED, which means that there may be flexibility in how the cell or gNB is turned OFF. For instance a specific sector can be turned OFF, or the whole cell or gNB may be turned OFF. While Cell DTX and / or Cell DRX is on-going, the cell shall still not affect random access procedure, SSB transmissions, paging and system information broadcasting. When Cell DTX is configured and during the so-called DTX non-active duration, the UE will not monitor PDCCH or SPS occasions. During this time, the UE may still transmit in the uplink, such as transmissions via Configured Grants (PUSCH) and Scheduling Requests (PUCCH). When Cell DRX is configured, the UE shall not perform transmissions during the so-called DTX non-active duration. This includes transmissions on Configured Grant (CG) and Scheduling Request (SR) resources. This to ensure that nothing is being transmitted by the UE so that a gNB does not have to monitor for any transmissions. Both Cell DTX and DRX has an on-duration, which is the active duration and a cycle that specifies the periodic repetition of the active duration and the non-active duration. The Cell DTX and Cell DRX are both configured via RRC, but the activation to start the Cell DTX and Cell DRX cycle are done via DCI via a new DCI format. For the new DCI format a new RNTI, nes-RNTI, is introduced. The DCI to activate or deactivate Cell DTX or Cell DRX will indicate things such as: - Field for activation / deactivation of Cell DTX Field for activation / deactivation of Cell DRX Field for which serving cell that the activation / deactivation concerns The Cell DTX and Cell DRX is configured in MAC-CellGroupConfig, which is a part of CellGroupConfig, in turn may be a part of RRCReconfiguration. Overview of RRC Resume procedures RRC Resume is performed to bring a UE out of the RRC inactive state. RRC Resume is started by the UE first synchronizing via random access and then transmitting RRCResumeRequest which contains the identifier of the UE, the i-RNTI, which is specifically used for RRC inactive. If the gNB is able to locate the UE context, i.e. the configuration of the UE, the gNB will reply with RRCResume, which may for instance contain a full configuration (else UE will used stored UE Inactive AS context for the connected mode configuration). The UE will restore security and the previous RRC configuration and then send the RRCResumeComplete, upon the procedure is completed the UE will have completed the RRC Resume procedures. The UE enters RRC inactive when it receives an RRCRelease with suspendConfig from a gNB. It can be triggered in a number of ways: UE initiated: o There is uplink traffic in the buffer. In this case the resume cause value used is mt-Access. o RAN Notification Area Update. This is triggered when the UE in RRC inactive camps on a cell which has a RAN-AreaCode which is not part of the UEs RAN Notification Area. The UEs RAN Notification Area is configured to a UE as part of the RRCRelease message when released to RRC inactive. o Expiry of timer T380, the periodic RAN Notification Area Update (RNAU) timer. In this case the cause value is rna-Update. Network-triggered: o UE receives a Paging message with a paging record matching its i-RNTI, i.e. a RAN-page. There are some cases where RRC resume procedure may be diverted, aborted or cases where a gNB may respond by not continuing with the RRC Resume procedures. These cases include: - T319 expiry: o T319 is the UE timer that puts a limit on how long a UE may perform RRC Resume. o Upon expiry the UE autonomously goes to RRC idle and lets upper layers deal with the re-connection. Receiving RRCSetup in response to RRCResumeRequest: o This can for instance occur if a gNB us unable to retrieve the UE context or any other errors preventing RRC Resume from being established. - Receiving RRCReject in response to RRCResumeRequest: o Can occur when the cell is overloaded or similar. In this case the UE may remain in RRC inactive and may be configured with a waitTime (T302), whereupon expiry the UE may re-attempt RRC Resume procedures. o This example is seen in Figure 5. - Receiving RRCRelease in response to RRCResumeRequest: o This is for instance used when the RNAU is being performed and the network swiftly sends the UE back to RRC inactive. Inability to comply with RRCResume: o In this case the UE will autonomously move to RRC idle. The messages in RRC Resume procedures are “RRCResumeRequest / RRCResumeRequestT’, “RRCResume” and “RRCResumeComplete”. Overview of RRC Re-establishment procedures The RRC Re-establishment procedure is performed after RLF in most cases and can also be performed when a UE fails a handover, as well as in cases of configuration failure. This can be seen along with the RLF in Figure 3. The steps are as follows: 1. RLF is declared. a. This can also be a Handover failure. 2. Idle mode cell selection. 3. (First performing random access and) Sending RRC Re-establishment request. 4. The gNB retrieving UE context from old gNB (if gNB is not the same as old). 5. Old gNB returning the UE context. 6. gNB replies with RRC Re-establishment and potentially reconfigures UE if needed, or continues using the same RRC configuration as previous. a. If reconfiguring the UE, the gNB replies with RRCSetup. 7. UE returning with RRC re-establishment is complete. The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present invention. SUMMARY It is an aim of certain examples of the present disclosure to address, solve and / or mitigate, at least partly, at least one of the problems and / or disadvantages associated with the related art, for example at least one of the problems and / or disadvantages described herein. It is an aim of certain examples of the present disclosure to provide at least one advantage over the related art, for example at least one of the advantages described herein. The present invention is defined in the independent claims. Advantageous features are defined in the dependent claims. Embodiments or examples disclosed in the description and / or figures falling outside the scope of the claims are to be understood as examples useful for understanding the present invention. Other aspects, advantages and salient features of the invention will become apparent to those skilled in the art from the following detailed description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 illustrates an example of Cell DTX along with its configured fields; Figure 2 illustrates an example of Cell DRX along with its configured fields; Figure 3 illustrates an example of RRC Release and RRC Resume; Figure 4 illustrates an example of Re-establishment procedure after an RLF; Figure 5 illustrates an example of a problem of performing RRC Resume or RRC reestablishment when applying Cell DRX and / or Cell DTX; Figure 6 illustrates an example of Saving RRC configuration except CellDTX-Config and CellDRX-Config in the UE Inactive AS context before going to RRC inactive; Figure 7 illustrates an example of Releasing CellDTX-Config and CellDRX-Config before performing RRCResumeRequest; Figure 8 illustrates an example of deactivating Cell DTX and Cell DRX; Figure 9 illustrates an example in which a UE performs RRC Resume to a cell different than the one it was released from; Figure 10 illustrates an exemplary method, for a UE, for handling cell discontinuous transmission and / or reception (CDTR); and Figure 11 is a block diagram of an exemplary network entity that may be used in certain examples of the present disclosure. DETAILED DESCRIPTION The following description of examples of the present disclosure, with reference to the accompanying drawings, is provided to assist in a comprehensive understanding of the present invention, as defined by the claims. The description includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the examples described herein can be made without departing from the scope of the invention. The same or similar components may be designated by the same or similar reference numerals, although they may be illustrated in different drawings. Detailed descriptions of techniques, structures, functions, operations or processes known in the art may be omitted for clarity and conciseness, and to avoid obscuring the subject matter of the present invention. The terms and words used herein are not limited to the bibliographical or standard meanings, but, are merely used to enable a clear and consistent understanding of the invention. Throughout the description and claims of this specification, the words “comprise”, “include” and “contain” and variations of the words, for example “comprising” and “comprises”, means “including but not limited to”, and is not intended to (and does not) exclude other features, elements, components, integers, steps, processes, operations, functions, characteristics, properties and / or groups thereof. Throughout the description and claims of this specification, the singular form, for example “a”, “an” and “the”, encompasses the plural unless the context otherwise requires. For example, reference to “an object” includes reference to one or more of such objects. Throughout the description and claims of this specification, language in the general form of “X for Y” (where Y is some action, process, operation, function, activity or step and X is some means for carrying out that action, process, operation, function, activity or step) encompasses means X adapted, configured or arranged specifically, but not necessarily exclusively, to do Y. Features, elements, components, integers, steps, processes, operations, functions, characteristics, properties and / or groups thereof described or disclosed in conjunction with a particular aspect, embodiment, example or claim are to be understood to be applicable to any other aspect, embodiment, example or claim described herein unless incompatible therewith. The skilled person will appreciate that the techniques described herein may be used in any suitable combination. Certain examples of the present disclosure provide one or more techniques for handling Cell DRX and / or Cell DRX states in a network. For example, certain examples provide one or more techniques for synchronising Cell DRX and / or Cell DTX states between a UE and a base station when the UE enters and exits an RRC inactive state in a 3GPP 5G NR network. However, the skilled person will appreciate that the present invention is not limited to these examples, and may be applied in any suitable system or standard, for example one or more existing and / or future generation wireless communication systems or standards, including any existing or future releases of the same standards specification, for example 3GPP 5G. The functionality of the various network entities and other features disclosed herein may be applied to corresponding or equivalent entities or features in the same or any other suitable communication systems or standards. Corresponding or equivalent entities or features may be regarded as entities or features that perform the same or similar role, function or purpose within the network. For example, the functionality of a RAN node (e.g. a base station, eNB or gNB) in the examples below may be applied to any other suitable type of entity performing RAN functions. A particular network entity may be implemented as a network element on a dedicated hardware, as a software instance running on a dedicated hardware, and / or as a virtualised function instantiated on an appropriate platform, e.g. on a cloud infrastructure. The skilled person will appreciate that the present invention is not limited to the specific examples disclosed herein. For example: • The techniques disclosed herein are not limited to 3GPP 5G. • One or more entities in the examples disclosed herein may be replaced with one or more alternative entities performing equivalent or corresponding functions, processes or operations. • One or more of the messages in the examples disclosed herein may be replaced with one or more alternative messages, signals or other type of information carriers that communicate equivalent or corresponding information. • One or more further elements or entities may be added to the examples disclosed herein. • One or more non-essential elements or entities may be omitted in certain examples. • The functions, processes or operations of a particular entity in one example may be divided between two or more separate entities in an alternative example. • The functions, processes or operations of two or more separate entities in one example may be performed by a single entity in an alternative example. • Information carried by a particular message in one example may be carried by two or more separate messages in an alternative example. • Information carried by two or more separate messages in one example may be carried by a single message in an alternative example. • The order in which operations are performed and / or the order in which messages are transmitted may be modified, if possible, in alternative examples. Certain examples of the present disclosure may be provided in the form of an apparatus / device / network entity configured to perform one or more defined network functions and / or a method therefor. Certain examples of the present disclosure may be provided in the form of a system (e.g. network or wireless communication system) comprising one or more such apparatuses / devices / network entities, and / or a method therefor. The Cell DTX / DRX is introduced to allow a gNB or a cell to power down momentarily. During these moments of powering down, the gNB or cell is expected to perform minimal amount of transmissions. The Cell DTX / DRX is controlled by the network in the sense that it may both be configured by a UE and then activated by physical layer signal, i.e. DCI in PDCCH. This makes it so that the network has a lot of control, to avoid cases where there are confusion between gNB and UE when to apply the Cell DTX or Cell DRX methods. During RRC inactive, the UE may save the UE RRC configuration, which would also include the Cell DRX and Cell DTX configuration. The issues that this may cause are for example: - The Cell DRX and DTX is active at the moment or just after the moment the UE is performing RRC Resume or RRC re-establishment. After the resumption or reestablishment the UE may not be allowed to transmit, making it difficult for the UE to fulfil the action that triggered the RRC Resume. An example of this can be seen in Figure 5. - During the time the UE is in RRC inactive and during the time the RRC reestablishment, the network may need / want to re-configure the Cell DTX or Cell DRX procedure. If for instance the UE performs RRC resume after having been in RRC inactive for several minutes, the UE may have moved within the cell, making the Cell DTX or Cell DRX no longer relevant in the specific sector of the cell. - The RNTI, nes-RNTI, to activate the Cell DRX and Cell DTX may be configured for multiple UEs, thus it may not be suitable to deactivate the Cell DRX or Cell DTX for a specific UE before releasing the UE to RRC inactive. Certain examples of the present disclosure provide one or more techniques for ensuring the Cell DRX and / or Cell DTX state is synchronized between UE and gNB (or associated cell). Certain examples of the present disclosure provide a method, for a User Equipment (UE), for handling cell discontinuous transmission and / or reception (CDTR), the method comprising: in response to receiving a first message to suspend a connection (e.g. the first message requesting, commanding, instructing, directing and / or indicating to suspend the connection; and / or indicating that the UE is required to suspend the connection): discarding configuration information related to CDTR without storing the configuration information in a UE inactive Access Stratum (AS) Context; and entering an inactive mode. In certain examples, the first message may comprise RRCRelease with suspendConfig. In certain examples, the inactive mode may comprise RRC INACTIVE. In certain examples, the configuration information may comprise CellDTXDRX-Config. In certain examples, the method may further comprise: in response to a certain condition being satisfied, performing a procedure to resume or establish a connection of the UE, wherein the configuration information applicable when the first message is received is not used when the procedure to resume or establish the connection is performed. In certain examples, performing the procedure to resume or establish the connection of the UE may comprise entering RRC CONNECTED mode. In certain examples, one or more items of configuration information, other than the configuration information related to CDTR, may be stored in the UE inactive AS context in response to receiving the first message. In certain examples, the UE may ignore any stored configuration information related to CDTR. In certain examples, the UE may not monitor for, or may ignore, messages indicating activation or deactivation of CDTR. In certain examples, the method may further comprise: in response to receiving the first message: discarding second configuration information related to monitoring for messages indicating activation or deactivation of CDTR (e.g. nes-RNTI) without storing the second configuration information in the UE inactive AS Context. In certain examples, the message indicating activation or deactivation of CDTR may comprise Downlink Control Information (DCI). Certain examples of the present disclosure (e.g. a first example) provide a method, for a UE, for handling cell discontinuous transmission and / or reception (CDTR), the method comprising: in response to receiving a first message (e.g. RRCRelease with suspendConfig) requesting to suspend a connection of the UE, entering an inactive mode (e.g. RRC inactive); and in response to a certain condition being satisfied, performing a procedure to resume or establish a connection of the UE (e.g. to enter RRC connected mode), wherein configuration information related to CDTR (e.g. CellDRX-Config and / or CellDRX-Config) applicable when the first message is received is not used when the procedure to resume the connection is performed. In certain examples (e.g. a second example according to the first example), the configuration information related to CDTR may be discarded after the first message is received. In certain examples (e.g. a third example according to the second example), discarding the configuration information may comprise entering the inactive mode without storing the configuration information in a UE inactive AS context. In certain examples (e.g. a fourth example according to the third example), one or more items of configuration information, other than the configuration information related to CDTR, may be stored in the UE inactive AS context. In certain examples (e.g. a fifth example according to the second example), discarding the configuration information may comprise: storing the configuration information in a UE inactive AS context when entering the inactive mode; and releasing the configuration information when exiting the inactive mode. In certain examples (e.g. a sixth example according to the fifth example), the configuration information may be released in response to the certain condition being satisfied. In certain examples (e.g. a seventh example according to the fifth example), the configuration information may be released in response to receiving a message (e.g. RRCResume) during the procedure to resume the connection. In certain examples (e.g. an eighth example according to the second example), the UE may ignore any stored configuration information related to CDTR. In certain examples (e.g. a ninth example according to any of the first to eighth examples), the UE may not monitor for, or ignore, messages indicating activation or deactivation of CDTR (e.g. DCI). Certain examples of the present disclosure (e.g. a tenth example) provide a method, for a UE, for handling cell discontinuous transmission and / or reception (CDTR), the method comprising: in response to receiving a first message (e.g. RRCRelease with suspendConfig) requesting to suspend a connection of the UE, entering an inactive mode (e.g. RRC inactive); and in response to a certain condition being satisfied, performing a procedure to resume or establish a connection of the UE (e.g. to enter RRC connected mode), wherein one or more state settings related to CDTR (e.g. activation states) are set (e.g. activated, deactivated, released) in the UE based on receiving the first message. In certain examples (e.g. an eleventh example according to the tenth example), setting the state settings may comprise: setting Cell DTX to active; or setting Cell DTX to inactive. In certain examples (e.g. a twelfth example according to the tenth or eleventh examples), setting the state settings may comprise: setting Cell DRX to active; or setting Cell DRX to inactive. In certain examples (e.g. a thirteenth example according to the tenth, eleventh or twelfth examples), the one or more state settings may be set or deactivated based on one or more of: one or more default settings; a network configuration; a hardcoded configuration (e.g. in the UE); a configuration received by the UE (e.g. in the first message or a separate message); and broadcast information (e.g. system information). In certain examples (e.g. a fourteenth example according to any of the tenth to thirteenth examples), the one or more state settings may be set based on one or more of: in response to a MAC layer in the UE being reset; in response to a MAC layer in the UE being reconfigured; in response to receiving the first message; in response to entering the inactive mode; and in response to initiating the procedure to resume or establish a connection. In certain examples (e.g. a fifteenth example according to any of the tenth to fourteenth examples), the method may further comprise receiving a message including one or more new state settings related to CDTR, after performing the procedure to resume or establish the connection. In certain examples (e.g. a sixteenth example according to the fifteenth example), the method may further comprise applying the new state settings. Certain examples of the present disclosure provide a UE configured to perform a method according to any example, embodiment, claim and / or aspect disclosed herein. Certain examples of the present disclosure provide a network (or wireless communication system) comprising a RAN entity, and a UE according to any example, embodiment, claim and / or aspect disclosed herein. Certain examples of the present disclosure provide a computer program comprising instructions which, when the program is executed by a computer or processor, cause the computer or processor to carry out a method according to any example, embodiment, claim and / or aspect disclosed herein. Certain examples of the present disclosure provide a computer or processor-readable data carrier having stored thereon a computer program according to any example, embodiment, claim and / or aspect disclosed herein. The skilled person will appreciate that any mention herein of Cell DTX and Cell DRX should be taken as Cell DTX and / or Cell DRX, if Cell DTX is configured and if Cell DRX is configured. In various examples disclosed herein, references to an inactive mode / state may be replaced with references to an idle mode / state, or similar mode / state. RRC Inactive aspects In RRC inactive the issue is that the UE may leave RRC inactive and attempt to enter RRC connected at very unpredictable times and according to RRC Release and Resume procedures the UE shall save all RRC configurations in the UE inactive context Thus there may state-confusion between UE and gNB. There are a number of techniques for dealing with Cell DTX and Cell DRX. For example, one or more of the following may be used for dealing with Cell DTX and Cell DRX: Option 1. Cell DRX and Cell DTX configuration are not saved in the UE context. Thus when receiving an RRC Release command to go to RRC inactive, the UE does not save the Cell DRX and Cell DTX configuration in the Inactive UE context. This can be configurable in the RRC Release message, configurable by RRC configuration, or be configured for all UEs. One specification example of this can be seen in Specification Example #1. As a further aspect, the nes-RNTI may also not be saved in the Inactive UE context and thus the UE will no longer monitor any nes-RNTI after having perform RRC Resume. This is reasonable as there is no reason to monitor for nes-RNTI after having released the Cell DRX and Cell DRX configuration. If the network needs the UE to perform Cell DRX or Cell DTX, the network may re-configure the UE after successful RRC resume. An example of this technique can be seen in Figure 6. Option 2. Cell DTX and Cell DRX configurations are released when the UE performs RRC Resume procedures. This can be released if configured by the network, or it may be default that when the UE performs RRC Resume procedures, the UE releases the Cell DTX and Cell DRX configurations. Specification example #2. Similar to the case above, the nes-RNTI may also be released so that the UE no longer monitors for DCI to activate / deactivate the Cell DRX and Cell DTX. A variation of this option is that the UE releases the Cell DTX and Cell DRX configurations upon receiving the RRCResume in response to the RRCResumeRequest. An example of this technique can be seen in Figure 7. Option 3. Cell DTX and Cell DTX configuration are saved in the UE context, but are deactivated by default when receiving RRCRelease. Thus RRC layer will send a deactivation indication to the MAC layer when the UE receives the RRCRelease with Suspend configuration. In this way, when the UE performs RRC Resume, the Cell DRX and Cell DTX are still configured in the MAC configuration, but is not activated. Specification example in example #3. After having successfully performed RRC resume, the UE may monitor for nes-RNTI and DCI to activate the Cell DRX and Cell DTX once again. This has the benefit that the gNB may quickly activate the Cell DRX and Cell DTX again if needed, but may also be problematic if the nes-RNTI have been configured for multiple UEs and the Cell DRX and / or Cell DTX configuration have changed when the UE is RRC inactive. An example of this technique can be seen in Figure 8. Option 4. Cell is deactivated when MAC is reset. The MAC reset may occur whenever RRC Release with suspend config is received or when the RRC Resume procedure to go to RRC connected is initiated. This may mean that whenever MAC is reset for any reason, the default is that MAC will deactivate the Cell DRX and / or Cell DTX configuration. This can be seen in specification example #4. This can also be done when a MAC entity is reconfigured. Option 5. Default Cell DTX and Cell DRX activation state when released to RRC inactive. There can be a default state introduced for Cell DTX and Cell DRX, which is used when the UE resumes from RRC inactive. This can be configured by the network or be hardcoded. If it is configured, then one example of how it can be used is that the network configures Cell DTX to have default state of deactivated, while Cell DRX has a default state of activated. This can also apply in other cases, such as when MAC is reset. Option 6. suspendConfig in RRCRelease indicates the Cell DTX and Cell DRX activation state (activated / deactivated), i.e. an RRC field cellDTX-DRX-State indicates the Cell DTX and Cell DRX configuration. Alternatively separate fields for Cell DRX and Cell DTX, i.e. cellDTX-State and cellDRX-State. If the Cell DTX and Cell DRX activation state is set to active, the UE may as an option decide to not perform RRC Resume at or before the duration of the Cell DRX / DTX. Whether the UE is allowed to wait may be configurable by the network. Option 7. Broadcasted configuration in the cell whether the cell DTX and / or Cell DRX is activated or deactivated upon RRC Release or RRC Resume. This can be broadcasted in System Information, such as SIB1 or any other System Information Block. Another sub-option is to define a new System Information Block with higher frequency which allows to change the activation status of the Cell DTX and Cell DRX much faster. In this case, a UE capable of Network Energy Saving via Cell DTX and Cell DRX may have to monitor the related System Information more often. For instance if the Cell DTX / DRX activation status is in SIB1, the UE acquires SIB1 every time before performing RRC Resume to ensure that the status of the Cell DRX / DTX is kept up to date. The activation field can be a single bit indicating whether Cell DRX or Cell DTX are activated, or two separate flags, one for Cell DRX and one for Cell DTX. The field in SIB1 can also indicate the default Cell DRX and Cell DRX config that all UEs shall apply. This can be used by default for a UE resuming from RRC inactive. The skilled person will appreciate that one or more of the above options may be combined, and for some cases, there may be capabilities for some of the actions. The above options may for instance apply to a cell group in a Dual Connectivity (DC) deployment. In other words, this may apply only to Master Cell Group (MCG) but not to a Secondary Cell Group (SCG), or only to SCG and not the MCG. For instance in an E-UTRA-NR DC (EN-DC) scenario, the techniques described herein may be applied only to the NR SCG and not the E-UTRA MCG. They may also be applied only to certain cell in a Cell Group (in other words a cell in a Carrier Aggregation scenario). This may mean that the Cell DRX and Cell DTX should not apply to the spCell (Primary Cell (PCell) or Primary SCG Cell (PSCell)), but Cell DRX and Cell DTX can apply to the Secondary Cells (SCell). If any cell group or SCell is not configured to be activated upon successful RRC Resume, the Cell DRX and DTX is not considered activated either for that specific cell or cell group. Some of the above actions such as release of Cell DTX and Cell DRX configurations may for instance be triggered in some specific cases such as emergency services. This means that when emergency services are triggered and the UE performs RRC Resume, the Cell DRX and Cell DTX configurations will be released. This can for instance be associated with the Resume cause emergency. In another case, it can be triggered when RNA update is performed. This may be important if the Cell DTX and Cell DRX configuration may stop any of the RRC messages from being transmitted and the UE mainly wants to perform a fast RNA update. Some of the options (e.g. Option 3, Option 4 and Option 5) may also be applicable in the case where the network sends a RRCSetup in response to UE’s RRCResumeRequest. In this case the network is unable to locate the UE context and thus need to perform RRC Setup instead of RRC Resume. In this case it is important that the Cell DTX and Cell DRX configurations are released. One or more of the techniques may also be applied if the UE performs RRC Resume to a cell different than the one that it was released from (to RRC inactive). For instance, if the UE resumes to a new cell, the UE will release the Cell DRX and Cell DTX configuration. This can be seen in Figure 9. RRC Re-establishment aspects Similar to the case of the RRC Resume from RRC inactive, there may be state confusion between Cell DRX and Cell DTX. For this case, in addition to the aspects listed below under the heading “Cell DRX and Cell DTX deactivation at MAC reset”, which may in some cases be used when the UE performs RRC re-establishment, some further options are: Option 8. The UE releases any Cell DTX or Cell DRX upon initiation of RRC Reestablishment, or upon receiving the RRC message RRCReestablishment in response to RRCReestablishmentRequest. Similarly, some of the options (e.g. Option 3, Option 4, Option 5 and Option 8) may also apply to the case where the network sends an RRCSetup in response to RRCReestablishmentRequest. Cell DRX and Cell DTX deactivation at MAC reset In certain examples, the Cell DTX / DRX is deactivated when the MAC is reset, both in the case of RRC inactive or RRC re-establishment. This may also be performed in other cases when the MAC is being reset, such as one or more of: During handovers. - Re-configuration with Sync (such as for SCell or SCG re-configuration, reconfiguration with or without security key refresh). - During or after Radio Link Failure (RLF). During RRC Connection Reject. During expiry of timers etc. The Cell DRX and Cell DTX deactivation may also be performed at MAC reconfiguration. The MAC reconfiguration is initiated upon MAC entity configuration via RRCReconfiguration message, when CellGroupConfig contains the mac-CellGroupConfig. In a variation of this technique, the Cell DRX and Cell DTX have a configured default state when MAC is reset. In this case it would be possible that Cell DRX or Cell DTX are activated if Cell DRX or Cell DTX have been configured by the gNB. Figure 10 illustrates an exemplary method, for a UE, for handling cell discontinuous transmission and / or reception (CDTR). Referring to Figure 10, in a first operation 1001, the UE determines whether a first message indicating that the UE is required to suspend a connection (e.g. RRCRelease with 5 suspendConfig) is received. If the first message is received, then a second operation 1002 and a third operation 1003 are performed in response. In the second operation 1002, the UE discards configuration information related to CDTR (e.g. CellDTXDRX-Config) without storing the configuration information in a UE inactive Access 10 Stratum (AS) Context. In the third operation 1003, the UE enters an inactive mode (e.g. RRC INACTIVE). Specification Examples Specification example #1 In this example, the Cell DRX and Cell DTX configurations are not saved in the UE Inactive AS context. Specification changes in red and bold text. 3^33^“' *3 33 331 ' 3 3 3333 5.3.8.3 Reception of the RRCRelease by the UE The UE shall: . . . OMITTED . . . 1> if the RRCRelease includes suspendConfig'. 2> reset MAC and release the default MAC Cell Group configuration, if any; 2> apply the received suspendConfig except the received nextHopChainingCount, . . . OMITTED . . . 2> if the UE is acting as L2 U2N Remote UE: . . OMITTED . . . 2> else: 3> re-establish RLC entities for SRB1; 2> if the RRCRelease message with suspendConfig was received in response to an RRCResumeRequest or an RRCResumeRequestl: . . . OMITTED . . . 2> else: 3> store in the UE Inactive AS Context the nextHopChainingCount received in the RRCRelease message, the current K8nb and KRRCintkeys, the ROHC state, the EHC context(s), the UDC state, the stored QoS flow to DRB mapping rules, the application layer measurement configuration, the C-RNTI used in the source PCell, the cellldentity and the physical cell identity of the source PCell, the spCellConfigCommon within Reconfiguration WithSync of the NR PSCell (if configured) and all other parameters configured except for: - parameters within Reconfiguration WithSync of the PCell; - parameters within Reconfiguration WithSync of the NR PSCell, if configured; - parameters within MobilityControllnfoSCG of the E-UTRA PSCell, if configured; - servingCellConfigCommonSIB', - sl-L2RelayUE-Config, if configured; - sl-L2Remote UE-Config, if configured; -■ and if configured; NOTE 1c: suspendConfig is not stored as part of UE Inactive AS Context, except for the fields explicitly specified. 3> store any previously or subsequently received application layer measurement report containers for which no segment, or full message, has been submitted to lower layers for transmission; NOTE 2: NR sidelink communication / discovery related configurations and logged measurement configuration are not stored as UE Inactive AS Context, when UE enters RRCINACTIVE. 2> suspend all SRB(s) and DRB(s) and multicast MRB(s), except SRBO and broadcast MRBs; 2> indicate PDCP suspend to lower layers of all DRBs and multicast MRBs; 2> release Uu Relay RLC channel(s), if configured; 2> release PC5 Relay RLC channel(s), if configured; 2> release the SRAP entity, if configured; 2> if the 1380 is included: 3> start timer T380, with the timer value set to 1380: 2> if the RRCRelease message is including the waitTime: 3> start timer T302 with the value set to the waitTime^ 3> inform upper layers that access barring is applicable for all access categories except categories '0' and '2'; 2> if T390 is running: 3> stop timer T390 for all access categories; 3> perform the actions as specified in 5.3.14.4; 2> indicate the suspension of the RRC connection to upper layers; 2> if the UE is capable of L2 U2N Remote UE: 3> enter RRC INACTIVE, and perform either cell selection as specified in TS 38.304

[20] , or relay selection as specified in clause 5.8.15.3, or both; 2> else: 3> enter RRC INACTIVE and perform cell selection as specified in TS 38.304

[20] ; 1> else: 2> perform the actions upon going to RRC IDLE as specified in 5.3.11, with the release cause 'other'. NOTE 3: Whether to release the PC5 unicast link is left to L2 U2N Remote UE's implementation. NOTE 4: It is left to UE implementation whether to stop T430, if running, when going to RRCINACTIVE. -------3GPP TS 38.331 V17.5.0 June 2023 version------- Specification example #2 In this case, the UE releases the Cell DTX and Cell DRX configuration upon initiating the RRC Resume procedures. •.............3GPP TS 38.331 V17.5.0 June 2023 version............. 5.3.13.2 Initiation The UE initiates the procedure when upper layers or AS (when responding to RAN paging, upon triggering RNA updates while the UE is in RRC INACTIVE, for NR sidelink communication / discovery / V2X sidelink communication as specified in clause 5.3.13.1a) requests the resume of a suspended RRC connection or requests the resume for initiating SDT as specified in clause 5.3.13.1b. Hie UE shall ensure having valid and up to date essential system information as specified in clause 5.2.2.2 before initiating this procedure. Upon initiation of the procedure, the UE shall: . . . OMITTED . . . 1> release referenceTimePreferenceReporting from the UE Inactive AS context, if stored; 1> release sl-AssistanceConfigNR from the UE Inactive AS context, if stored; 1> release musim-GapAssistanceConfig from the UE Inactive AS context, if stored and stop timer T34611, if running; 1> release musim-GapConfig from the UE Inactive AS context, if stored; 1> release and from the UE Inactive AS context, if stored; 1> release musim-LeaveAssistanceConfig from the UE Inactive AS context, if stored; 1> reiease propDelayDiffReportConfig from the UE Inactive AS context, if stored; 1> release iil-GapFR2-PreferenceConflg, if configured; 1> release rrm-MeasRelaxationReportingConfig from the UE Inactive AS context, if stored; 1 >if the UE is acting as L2 U2N Remote UE: 2> apply the specified configuration of SL-RLCO used for the de liven of RRC message over SRBO as specified in 9.1.1.4; 2> apply the SDAP configuration and PDCP configuration as specified in 9.1.1.2 for SRBO; 1> else: 2> apply the CCCH configuration as specified in 9.1.1.2; 2> apply the timeAlignmentTimerCommon included in SIB I ; 1> if sdt-MAC-PHY-CG-Config is configured: 2> if the resume procedure is initiated m a cell that is different to tire PCell in which the UE received the stored sdt-MAC-PHY-CG-Config-. 3> release the stored sdt-MAC-PHY-CG-Config-, 3> instruct the MAC entity to stop the cg-SDT-TimeAlignmentTimer, if it is running; 1> if ncd-SSB-RedCapInitialBWP-SDT is configured: 2> if the resume procedure is initiated in a cell that is different to the PCell in which the UE received the stored ncd-SSB-RedCapInitialBWP-SDT-. 3> release the stored ncd-SSB-RedCapInitialBWP-SDT; 1> if conditions for initiating SDT in accordance with 5.3.13.1b are fulfilled: 2> consider the resume procedure is initiated for SDT; 2> start timer T319a when the lower layers first transmit the CCCH message; 2> consider SDT procedure is ongoing; 1> else: 2> start timer T319; 2> instruct the MAC entity to stop the cg-SDT-TimeAlignmentTimer, if it is running; 1 >if la-Report is configured with value enabled and the UE supports TA reporting: 2> indicate TA report initiation to lower layers; 1> set the variable pendingRNA-Update to false', 1> release successHO-Config from the UE Inactive AS context, if stored; 1 >initiate transmission of the RRC Resume Request message or RRCResumeRequestl in accordance with 5.3.13.3. -------3GPP ts 38.331 V17 5.0 June 2023 version------- Specification example #3 In this example, the UE RRC layer indicates to the UE MAC layer to deactivate any Cell DTX and Cell DRX configurations. 5.3.8.3 Reception of the RRCRelease by the UE The UE shall: . . OMITTED . . . 1> if the RRCRelease includes suspendConfig-. 2> reset MAC and release the default MAC Cell Group configuration, if any; 2> apply the received suspendConfig except the received nextHopChainingCount, . . . OMITTED . . . 2> if the UE is acting as L2 U2N Remote UE: . . . OMITTED . . . 2> else: 3> re-establish RLC entities for SRB1; 2> if the RRCRelease message with suspendConfig was received in response to an RRCResume Request or an RR('ResumeRequest I: . . OMI TTED . . . 2> else: 3> store in the UE Inactive AS Context tire nextHopChainingCount received in the RRCRelease message, the current K8nb and KRRCmtkeys, the ROHC state, the EHC context(s), the UDC state, the stored QoS flow to DRB mapping rules, the application layer measurement configuration, the C-RNTI used in the source PCell, the cellidentity and the physical cell identity of the source PCell, the spCellConfigCommon within ReconfigurationWithSync of the NR PSCell (if configured) and all other parameters configured except for: - parameters within Reconfiguration WithSync of the PCell; - parameters within Reconfiguration WithSync of the NR PSCell, if configured; - parameters within MobilityControlInfoSCG of the E-UTRA PSCell, if configured; - servingCellConfigCommonSIB-, - sl-L2RelayUE-Config, if configured; - sl-L2Remote UE-Config, if configured; NOTE 1c: suspendConfig is not stored as part of UE Inactive AS Context, except for the fields explicitly specified. 3> store any previously or subsequently received application layer measurement report containers for which no segment, or full message, has been submitted to lower layers for transmission; NOTE 2: NR sidelink communication / discovery related configurations and logged measurement configuration are not stored as UE Inactive AS Context, when UE enters RRCJNACTIVE. 2> suspend all SRB(s) and DRB(s) and multicast MRB(s), except SRBO and broadcast MRBs; 2> indicate PDCP suspend to lower layers of all DRBs and multicast MRBs; 2> release Uu Relay RLC channel(s), if configured; 2> release PC5 Relay RLC channel(s), if configured; 2> release the SRAP entity, if configured; 2> indicate to MCG MAC entity to deactive any Cell DTX or Cell DRX configuration; 2> if the t380 is included: 3> start timer T380, with the timer value set to t380', 2> if the RRCRelecise message is including the waitTime'. 3> start timer T302 with the value set to the waitTime-, 3> infomi upper layers that access barring is applicable for all access categories except categories '0' and '2'; 2> if T390 is running: 3> stop timer T390 for all access categories; 3> perform the actions as specified in 5.3.14.4; 2> indicate the suspension of the RRC connection to upper layers; 2> if the UE is capable of L2 U2N Remote UE: 3> enter RRCJNACTIVE, and perform either cell selection as specified in TS 38.304

[20] , or relay selection as specified in clause 5.8.15.3, or both; 2> else: 3> cntcr RRC [\ACTIVE and perform cell selection as specified in TS 38.304

[20] ; 1> else: 2> perform the actions upon going to RRCIDLE as specified in 5.3.11, with the release cause 'other'. NOTE 3: Whether to release the PC5 unicast link is left to L2 U2N Remote UE's implementation. NOTE 4: It is left to UE implementation whether to stop T430, if running, when going to RRCJNACTIVE. -------3GPP TS 38.331 V17.5.0 June 2023 version------- Specification example #4 In this example, the UE will deactivate the Cell DRX or Cell DTX upon MAC reset. -------3GPP TS 38.321 V17.5.0 June 2023 version------- 5.12 MAC Reset If a reset of the MAC entity is requested by upper layers or the reset of the MAC entity is triggered due to SCG deactivation as defined in clause 5.29, the MAC entity shall: 1> if the MAC reset is not due to SCG deactivation: 2> initialize Bj for each logical channel to zero; 1> initialize SBj for each logical channel to zero if Sidelink resource allocation mode 1 is configured by RRC; 1> if upper layers indicate SCG deactivation and bfd-and-RLM with value true is configured for the deactivated SCG: 2> stop (if running) all timers except beamFailureDetectionTimer associated with PSCell and timeAlignmentTimers. 1> else: 2> stop (if running) all timers, except MBS broadcast DRX timers; 2> consider all timeAlignmentTimers, inactive? osSRS-TimeAlignmentTimer, and cg-SDT-TimeAlignmentTimer, if configured, as expired and perform the corresponding actions in clause 5.2; I >set the NDIs for all uplink HARQ processes to the value 0; 1 >sets the NDIs for all HARQ process IDs to the value 0 for monitoring PDCCH in Sidelink resource allocation mode 1; 1> stop, if any, ongoing Random Access procedure; 1> discard explicitly signalled contention-free Random Access Resources for 4-step RA type and 2-step RA type, if any; 1> flush Msg3 buffer; 1> flush MSGA buffer; 1> cancel, if any, triggered Scheduling Request procedure; 1> cancel, if any, triggered Buffer Status Reporting procedure; 1> cancel, if any, triggered Power Headroom Reporting procedure; 1> cancel, if any, triggered consistent LBT failure; 1> cancel, if any, triggered BFR; 1> cancel, if any, triggered Sidelink Buffer Status Reporting procedure; 1> cancel, if any, triggered Pre-emptive Buffer Status Reporting procedure; 1> cancel, if any, triggered Timing Advance Reporting procedure; 1> cancel, if any, triggered Recommended bit rate query procedure; 1> cancel, if any, triggered Configured uplink grant confirmation; 1> cancel, if any, triggered configured sidelink grant confirmation; 1> clear, if any, configured side link grants; 1> cancel, if any, triggered Desired Guard Symbol query; 1> cancel, if any, triggered Positioning Measurement Gap Activation / Deactivation Request procedure; 1> cancel, if any, triggered SDT procedure; 1> cancel, if any, triggered IAB-MT Recommended Beam Indication query; 1> cancel, if any, triggered Desired DL TX Power Adjustment query; 1> cancel, if any, triggered Desired IAB-MT PSD range queiy: 1> cancel, if any, triggered Case-6 Timing Request query; 1> flush the soft buffers for all DL HARQ processes, except for the DL HARQ process being used for MBS broadcast: 1> for each DL HARQ process, except for the DL HARQ process being used for MBS broadcast, consider the next received transmission for a TB as the very first transmission; 1> deactivate any Cell DTX or Ceil DRX configuration; 1> release, if any, Temporary C-RNTI; 1> if upper layers indicate SCG deactivation and bfd-and-RLM with value true is not configured; or 1 >if the MAC reset is not due to SCG deactivation: 2> reset all BFI^COUNTERS', 1> reset all LBTCOUNTERS. -------3GPP TS 38.321 V17.5.0 June 2023 version------- Figure 11 is a block diagram of an exemplary network entity that may be used in examples of the present disclosure. For example, a UE and / or base station in the examples of Figures 1-10 may comprise an entity of Figure 11. The skilled person will appreciate that a network entity may be implemented, for example, as a network element on a dedicated hardware, as a software instance running on a dedicated hardware, and / or as a virtualised function instantiated on an appropriate platform, e.g. on a cloud infrastructure. The entity 1100 comprises a processor (or controller) 1101, a transmitter 1103 and a receiver 1105. The receiver 1105 is configured for receiving one or more messages from one or more other network entities, for example as described above. The transmitter 1103 is configured for transmitting one or more messages to one or more other network entities, for example as described above. The processor 1101 is configured for performing one or more operations, for example according to the operations as described above. The techniques described herein may be implemented using any suitably configured apparatus and / or system. Such an apparatus and / or system may be configured to perform a method according to any aspect, embodiment, example or claim disclosed herein. Such an apparatus may comprise one or more elements, for example one or more of receivers, transmitters, transceivers, processors, controllers, modules, units, and the like, each element configured to perform one or more corresponding processes, operations and / or method steps for implementing the techniques described herein. For example, an operation / function of X may be performed by a module configured to perform X (or an X-module). The one or more elements may be implemented in the form of hardware, software, or any combination of hardware and software. It will be appreciated that examples of the present disclosure may be implemented in the form of hardware, software or any combination of hardware and software. Any such software may be stored in the form of volatile or non-volatile storage, for example a storage device like a ROM, whether erasable or rewritable or not, or in the form of memory such as, for example, RAM, memory chips, device or integrated circuits or on an optically or magnetically readable medium such as, for example, a CD, DVD, magnetic disk or magnetic tape or the like. It will be appreciated that the storage devices and storage media are embodiments of machine-readable storage that are suitable for storing a program or programs comprising instructions that, when executed, implement certain examples of the present disclosure. Accordingly, certain examples provide a program comprising code for implementing a method, apparatus or system according to any example, embodiment, aspect and / or claim disclosed herein, and / or a machine-readable storage storing such a program. Still further, such programs may be conveyed electronically via any medium, for example a communication signal carried over a wired or wireless connection. While the invention has been shown and described with reference to certain examples, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the invention, as defined by the appended claims. References 5 [1] RP-230566, “WID Revision: Network energy savings for NR”, Huawei, RAN#99, Rotterdam, Netherlands, March 2023. [2] 3GPP TR 38.864, “Study on network energy savings for NR, V18.1.0, Release 18, March 2023. [3] 3GPP TS 38.321 V17.5.0 “Medim Access Control (RRC) protocol specification”, 10 Release 17, June 2023. [4] 3GPP TS 38.331 V17.5.0 “Radio Resource Control (RRC)”, Release 17, June 2023. Acronyms In the present disclosure, the following acronyms / definitions may be used. 3GPP 5G 3rd Generation Partnership Project 5th Generation 5 AS Access Stratum CDTR Cell DTX and / or Cell DRX CG Configured Grant CHO Conditional Handover CSI Channel State Information 10 DC Dual Connectivity DCI Downlink Control Information DL DownLink DRB Data Radio Bearer DRX Discontinuous Reception 15 DTX Discontinuous Transmission eNB Base Station EN-DC E-UTRA NR DC E-UTRA Evolved Universal Terrestrial Radio Access gNB 5G Base Station 20 ID Identity / ldentifi cation IE Information Element MAC Medium Access Control MCG Master Cell Group MT Mobile Terminated 25 NES Network Energy Saving NR New Radio OPEX Operating Expenditure PCell Primary Cell PDCCH Physical Downlink Control Channel 30 PDSCH Physical Downlink Shared Channel PSCell Primary SCG Cell PUCCH Physical Uplink Control Channel PUSCH Physical Uplink Shared Channel RAN Radio Access Network 35 Rei Release RLF Radio Link Failure RNA RAN Notification Area RNAU RAN Notification Area Update RNTI Radio Network Temporary Identifier 40 RRC Radio Resource Control RS Reference Signal SCell Secondary Cell SCG Secondary Cell Group SIB System Information Block 45 spCell Primary Cell SPS Semi Persistent Scheduling SR Scheduling Request SRB Signal Radio Bearer SSB Synchronization Signal Block 50 TR Technical Report TS Technical Specification Txxx Timer xxx UE User Equipment Wl Work Item

Claims

1. A method, for a User Equipment (UE), for handling cell discontinuous transmission and / or reception (CDTR), the method comprising:in response to receiving a first message indicating that the UE is required to suspend a connection:discarding configuration information related to CDTR without storing the configuration information in a UE inactive Access Stratum (AS) Context; andentering an inactive mode.

2. A method according to claim 1, wherein the first message comprises RRCRelease with suspendConfig.

3. A method according to claim 1 or 2, wherein the inactive mode comprises RRC INACTIVE.

4. A method according to claim 1, 2 or 3, wherein the configuration information comprises CellDTXDRX-Config.

5. A method according to any preceding claim, further comprising:in response to a certain condition being satisfied, performing a procedure to resume or establish a connection of the UE,wherein the configuration information applicable when the first message is received is not used when the procedure to resume or establish the connection is performed.

6. A method according to claim 5, wherein performing the procedure to resume or establish the connection of the UE comprises entering RRC CONNECTED mode.

7. A method according to any preceding claim, wherein one or more items of configuration information, other than the configuration information related to CDTR, are stored in the UE inactive AS context in response to receiving the first message.

8. A method according to any preceding claim, wherein the UE ignores any stored configuration information related to CDTR.

9. A method according to any preceding claim, wherein the UE does not monitor for, or ignores, messages indicating activation or deactivation of CDTR.

10. A method according to any preceding claim, further comprising: in response to receiving the first message:discarding second configuration information related to monitoring for messages indicating activation or deactivation of CDTR (e.g. nes-RNTI) without storing the second configuration information in the UE inactive AS Context11. A method according to claim 9 or 10, wherein the message indicating activation or deactivation of CDTR comprises Downlink Control Information (DCI).

12. A UE configured to perform a method according to any preceding claim.

13. A network or wireless communication system comprising a UE according to claim 12 and a Radio Access Network (RAN) entity.

14. A computer program comprising instructions which, when the program is executed by a computer or processor, cause the computer or processor to carry out a method according to any of claims 1 to 11.

15. A computer or processor-readable data carrier having stored thereon a computer program according to claim 14.

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