Improvements in small data transmissions

Abstract

According to an aspect, there is provided a method performed by a user equipment, UE, in a communication network. The method comprising: transmitting (301) data to, or receiving data from, a first Radio Access Network, RAN, node using a Small Data Transmission, SDT, procedure; transmitting (303) one or more reference signals for measurement by the first RAN node; and receiving (305) a first indication from the first RAN node of one or more resources to be used for further data transmissions by the UE using the SDT procedure.

Description

[0001] Improvements in Small Data Transmissions

[0002] Technical Field

[0003] This disclosure relates to Small Data Transmission (SDT) in a communication network, and in particular to scheduling resources and / or link adaptation for transmissions using SDT.

[0004] Background

[0005] New Radio (NR) small data transmissions in Inactive state - In Release 15 (Rel-15), the 3rdGeneration Partnership Project (3GPP) introduced a new radio-access technology known as New Radio (NR). In NR, a terminal device (user equipment - UE) can be in one of a number of Radio Resource Control (RRC) states: RRC idle (RRCJdle), RRC connected (RRC_Connected) or RRC inactive (RRCJnactive). Until Release 16, data transmission was only possible when the UE was in RRC connected. Therefore, the UE must transition to a connected state from idle or inactive states every time there is data transfer between UE and a radio access network (RAN) node, e.g. a gNB. The transition from RRCJdle or RRCJnactive state to RRC_Connected leads to significant signalling overhead and power consumption, particularly for the UEs that need infrequent transmission of small data packets. In the RRCJnactive state, the UE has established a RRC context and a core network connection. Therefore, the transition from Inactive to Connected state is relatively fast and requires less signalling compared to the transition from Idle to Connected state.

[0006] In order to enable efficient transmission of small infrequent data packets, 3GPP has approved a new study item on NR small data transmissions in RRCJnactive state. In Release 17 (Rel-17), this specified Mobile Originated Small Data Transmission (MO-SDT) to allow small packet transmission for uplink (UL)-oriented packets. A Work Item 3GPP RP-200954 “New Work Item on NR small data transmissions in INACTIVE state” (by ZTE in 3GPP TSG RAN Meeting #86) was started for Rel-17 with the focus of optimising the transmission for UL-initiated small data payloads by reducing the signalling overhead. The Wl contains the following relevant objectives:

[0007] In Release 18 (Rel-18) Mobile Terminated (MT) SDT is specified, that is downlink (DL)- triggered small data, to allow similar benefits, i.e. 1) reducing signalling overhead and UE power consumption by not transitioning to RRC_CONNECTED and reducing latency by allowing fast transmission of (small and infrequent) packets, e.g. for positioning. The scope of this work item majorly addresses two main objectives. A Rel-18 MT-SDT work item description (WID) can be found in 3GPP RP-222993 “Revised Wl: Mobile Terminated-Small Data Transmission (MT-SDT) for NR” (by ZTE, 3GPP TSG RAN Meeting #98e). The WID contains the following objectives:

[0008] In short, the MO-SDT procedure is triggered by the UE receiving UL data in its buffer. If the UL data is mapped to a Data Radio Bearer (DRB) configured for SDT it further checks that the data volume is below a Data Volume Threshold (DVT) and that the Reference Signal Received Power (RSRP) is above a configured threshold. If these conditions are satisfied it initiates the SDT procedure. It may then use either Configured Grant-SDT (CG-SDT) or Random Access SDT (RA-SDT) based access.

[0009] The CG-SDT uses configured grants and requires the UE to remain in the cell where it was released to inactive and that its RSRP does not change more than a threshold from the RSRP it had when it was released to inactive. There is also a specific timing advance timer (TAT), CG- SDT-TAT, which must be running.

[0010] When the 2-step Random Access (RA) is applied for SDT, the Message A (MsgA) will contain the RRCResumeRequest message and User Plane (UP) data. The gNB will, as in the legacy case, respond with the contention resolution identity (CR-ID) to resolve contention. It will also send a Cell-Radio Network Temporary Identifier (C-RNTI) and the UE will monitor Physical Downlink Control Channel (PDCCH) for Downlink Control Information (DCI) scrambled by C-RNTI to obtain new UL grants or assignments for DL data, in case subsequent transmissions are needed.

[0011] As for the 4-step RA procedure, the SDT procedure ends when the gNB sends a RRCRelease with suspend config message and thereby keeps the UE in Inactive state. Alternatively, the gNB may instead send a RRCResume and move the UE to connected state.

[0012] When the 4-step RA is applied for SDT, the Message 3 (Msg3) will contain the RRCResumeRequest message and UP data. The gNB will, as in the legacy case, respond with the contention resolution ID (CR-ID) to resolve contention and at this point the Temporary C-RNTI (TC-RNTI) will be used by the UE as C-RNTI, i.e. the UE will monitor PDCCH for DCI scrambled by C-RNTI to obtain new UL grants or assignments for DL data, in case subsequent transmissions are needed. The SDT procedure ends when the gNB sends a RRCRelease with suspend config message and thereby keeps the UE in Inactive state. Alternatively, the gNB may instead send a RRCResume and move the UE to connected state.

[0013] The specification of MT-SDT is currently ongoing in 3GPP Rel-18. It will be initiated by the gNB paging the UE for MT-SDT. The UE will then follow the procedure of MO-SDT, except that it will not transmit any data in the first UL transmission and may receive data in DL already in Message 4 (Msg4) or Message B (MsgB).

[0014] For Narrowband-Internet of Things (NB-loT) and Long Term Evolution Machine-Type Communication (LTE-M) similar signalling optimisations for small data have been introduced through Rel-15 Early Data Transmission (EDT) and Rel-16 Preconfigured Uplink Resources (PUR). The main difference for the NR SDT solutions are that the Rel-17 NR Small Data is only to be supported for the RRC INACTIVE state, includes also 2-step RACH based small data, and that it should also include regular complexity Mobile Broadband (MBB) UEs. Both support mobile originated (MO) traffic only. NR SDT also, unlike LTE EDT, supports transmission of subsequent data, that is, larger payload sizes which require more than one transmission.

[0015] For Rel-19, several suggestions for improvements and enhancements have been proposed by companies. Among the proposals, allowing a larger DVT, i.e. using MO-SDT, is among the proposals.

[0016] Summary

[0017] There currently exist certain challenge(s). In Rel-17, MO-SDT targets relatively small UL transmissions. The parameter sdt-DataVolumeThreshold controls the maximum size of data that can be in the UE’s UL buffer when the MO-SDT procedure is initiated. Even though the parameter allows a rather large data volume, i.e. the maximum value is 96 KBytes (KB), the procedure will not be equally efficient compared to resuming to connected mode and performing the transmissions there. A main reason is that the gNB has very limited knowledge of the UL radio conditions, and therefore needs to schedule the UE in a conservative way, i.e. using small Transport Block (TB) and low Modulation and Coding Scheme (MCS). The only information that the gNB has of the radio conditions is that the UE-measured DL RSRP is above the sdt-RSRP- Threshold, if this parameter is configured.

[0018] Better knowledge of the UL radio conditions would enable more efficient UL scheduling and link adaptation, and thereby better performance of MO-SDT when larger amounts of data are to be transmitted. Similarly for MT-SDT, scheduling of larger UL data is not efficient due to lack of UL radio channel knowledge.

[0019] Therefore, there is need for improvements in the information available to the network when scheduling resources and / or adapting a link for transmissions of data using SDT.

[0020] Certain aspects of the disclosure and their embodiments may provide solutions to these or other challenges.

[0021] This disclosure proposes the use of reference signal transmissions (e.g. Sounding Reference Signal (SRS) transmissions) in SDT procedures. In particular, this disclosure provides techniques for a UE using SDT to transmit and / or receive data to perform reference signal (e.g. SRS) transmissions to allow the gNB to estimate the UL radio conditions and thereby perform a more efficient scheduling of resources for the UE to transmit UL data according to SDT. In some embodiments the gNB can indicate to the UE if or when to start reference signal (e.g. SRS) transmissions, but in other embodiments the UE can start reference signal (e.g. SRS) transmissions autonomously. In some embodiments, the reference signal configuration can be given to the UE in a (prior) RRC Release message. In other embodiments, the reference signal configuration(s) can be provided in System Information (SI). Different triggers to use these (e.g. when the UE has UL data to transmit) can be defined, and this disclosure also provides indications from gNBs as to which reference signal resource(s) to use.

[0022] According to a first aspect, there is provided a method performed by a UE in a communication network. The method comprises transmitting data to, or receiving data from, a first Radio Access Network, RAN, node using a SDT procedure; transmitting one or more reference signals for measurement by the first RAN node; and receiving a first indication from the first RAN node of one or more resources to be used for further data transmissions by the UE using the SDT procedure.

[0023] According to a second aspect, there is provided a method performed by a first RAN node in a communication network. The method comprises: transmitting data to, or receiving data from, a user equipment, UE, using a SDT procedure; measuring one or more reference signals transmitted by the UE; determining, based on the measurements of the one or more reference signals, one or more resources to be used for further data transmissions by the UE using the SDT procedure; and sending a first indication to the UE of the one or more resources.

[0024] According to a third aspect, there is provided a computer program product comprising a computer readable medium having computer readable code embodied therein. The computer readable code is configured such that, on execution by a suitable computer or processor, the computer or processor is caused to perform the method according to the first aspect, the second aspect, or any embodiments thereof.

[0025] According to a fourth aspect, there is provided a UE configured to perform the method according to the first aspect or any embodiment thereof.

[0026] According to a fifth aspect, there is provided a UE comprising a processor and a memory, said memory containing instructions executable by said processor whereby said UE is operative to perform the method according to the first aspect or any embodiment thereof.

[0027] According to a sixth aspect, there is provided a first RAN node configured to perform the method according to the second aspect or any embodiment thereof.

[0028] According to a seventh aspect, there is provided a first RAN node comprising a processor and a memory, said memory containing instructions executable by said processor whereby said first RAN node is operative to perform the method according to the second aspect or any embodiment thereof.

[0029] Certain embodiments may provide one or more of the following technical advantage(s). In particular, the techniques described herein enable more efficient scheduling and link adaptation for UL transmissions in SDT.

[0030] Brief Description of the Drawings

[0031] Some of the embodiments contemplated herein will now be described more fully with reference to the accompanying drawings, in which:

[0032] Fig. 1 is a timeline illustrating the signalling where 4-step random access is used for MO- SDT according to an embodiment;

[0033] Fig. 2 is a timeline illustrating the signalling where 4-step random access is used for MT- SDT according to an embodiment;

[0034] Fig. 3 is a flow chart illustrating a method performed by a UE in accordance with some embodiments;

[0035] Fig. 4 is a flow chart illustrating a method performed by a first RAN node in accordance with some embodiments;

[0036] Fig. 5 shows an example of a communication system in accordance with some embodiments;

[0037] Fig. 6 shows a UE in accordance with some embodiments;

[0038] Fig. 7 shows a RAN network node in accordance with some embodiments; and

[0039] Fig. 8 is a block diagram illustrating a virtualization environment in which functions implemented by some embodiments may be virtualized.

[0040] Detailed Description

[0041] Some of the embodiments contemplated herein will now be described more fully with reference to the accompanying drawings. Embodiments are provided by way of example to convey the scope of the subject matter to those skilled in the art.

[0042] As noted above, this disclosure provides techniques for an SDT UE to apply reference signal (e.g. SRS) transmissions to allow the gNB to estimate the UL radio conditions and thereby perform a more efficient UL scheduling. An ‘SDT UE’ or a UE that is operating according to a SDT process / procedure, or a UE that transmits and / or receives data according to or using SDT, is a UE that transmits and / or receives data while the UE is in an inactive state and without the UE having to switch to a connected state.

[0043] In some embodiments the gNB can indicate to the UE if or when to start reference signal (e.g. SRS) transmissions, but in other embodiments the UE can start reference signal (e.g. SRS) transmissions autonomously. While in this disclosure the reference signals are described as SRS, it will be appreciated that other types of reference signals could be transmitted by the UE.

[0044] The transmission of the reference signals can be in accordance with a reference signal configuration. Thus, the reference signal configuration defines or is used to configure reference signal transmissions. The reference signal configuration can define or specify resources (e.g. SRS resources) to be used for the reference signal transmissions. The reference signal configuration can defines one or more sets of these resources (e.g. SRS-ResourceSets), and provide a list of resource sets. The network may trigger the transmission of reference signals according to one of the sets of resources using control signalling, e.g. Layer 1 (L1) signalling, Downlink Control Information (DCI).

[0045] Fig. 1 is a timeline illustrating the signalling according to an exemplary embodiment of the techniques described herein where 4-step random access (RA) is used for MO-SDT, where the reference signal configuration is provided in a RRC Release message, and the network (i.e. RAN node / gNB) sends an indication to the UE to start the reference signal transmissions.

[0046] In Fig. 1 , arrows directed downwards represent signalling / transmissions from a RAN node / gNB to a UE (i.e. DL transmissions), and arrows directed upwards represent signalling / transmissions from a UE to a RAN node / gNB (i.e. UL transmissions). In brief, in this embodiment a SRS configuration, or information (e.g. an index) identifying one or more SRS configurations to use, is carried in a RRCRelease message from the gNB, and Message 4 (Msg4) is used by the gNB to activate the SRS transmissions by the UE. Scheduling of subsequent UL data can be based on the gNB’s observations of the UE’s SRS transmissions.

[0047] Thus, in Fig. 1 , signal 102 represents the release message (RRC_Release) that includes one or more SRS configurations, or information identifying one or more SRS configurations to use, that is sent to the UE by the gNB. The release message 102 is sent to the UE when the UE is released to an inactive state.

[0048] Subsequently, the UE has UL data in its buffer, and so the UE initiates the 4-step RA process by sending a RA preamble 104 to the gNB. The RA preamble 104 is also referred to as Message 1 (Msg1). The gNB responds to the RA preamble 104 with a response message 106 (e.g. a Random Access Response (RAR)). The response message 106 allocates / schedules a resource(s) for the UE to transmit the next message in the procedure. The response message 106 is also referred to as Message 2 (Msg2).

[0049] The UE can then send the UL data in a connection request message 108, e.g. Message 3 (Msg3) 108 of the 4-step RA procedure. Msg3 108 is sent in the allocated / scheduled resource(s). Msg3 108 may be a RRC Connection Request message.

[0050] The gNB then sends a message 110 to the UE in response to Msg3 108. This response 110 is Msg4 in the 4-step RA procedure, and therefore can be a RRC Connection Release message. The response 110 activates the SRS transmissions according to the SRS configuration signalled in signal 102, and response 110 is also used for contention resolution (CR). Thus, on or after receiving response 110, the UE starts transmitting SRS according to the SRS configuration.

[0051] The gNB measures the SRS transmitted by the UE and uses the measurements to schedule UL data transmissions by the UE. The gNB sends downlink control information (DCI) 112 to the UE that indicates the UL resources to be used by the UE to transmit UL data. Signals 114 represent the UL data transmitted by the UE using the scheduled resources.

[0052] As noted above, in the embodiment of Fig. 1 , one or more SRS configurations (or information identifying one or more SRS configurations to use) can be provided in RRC Release message 102. However, in alternative embodiments, one or more SRS configuration(s), or information identifying one or more SRS configurations to use, can be signalled to the UE(s) in System Information (SI) broadcast by the gNB (not shown in Fig. 1), or contained in the response message 106 (e.g. RAR).

[0053] If multiple SRS configurations are provided in RRC Release message 102 or signalled in SI, or otherwise already stored in the UE, the gNB can indicate which SRS configuration the UE is to use, for example by including a suitable indication in the RRC Release message 102, or in the response 110 (e.g. Msg4). In this case, the different SRS configurations can be indexed by respective numbers, and the gNB can indicate an index for the SRS config u ration (s) to be used. In an alternative approach, the UE can randomly select the SRS configuration to use from the multiple available SRS configurations.

[0054] If only one SRS configuration is signalled in the RRC Release message 102 or SI, it will be clear to the UE which SRS configuration it should use.

[0055] Signalling the SRS configuration(s) in a release message 102 or in SI enables the same SRS configuration to be provided to multiple UEs.

[0056] In an alternative approach, rather than provide the SRS configuration in RRC Release message 102 or in SI, the UE can use a SRS configuration that the UE had when it was in connected mode (e.g. RRC_Connected) before being released to inactive (e.g. RRCJnactive). The UE can store such a SRS configuration when in connected mode, and use it during the SDT procedure.

[0057] For any of the above embodiments, the SRS configuration may be mapped to a specific Synchronisation Signal Block (SSB). This means that there may be multiple SRS configurations / SRS resources configured to the UE, where each SRS configuration / SRS resource is associated with or mapped to different SSBs. In this case, the UE can measure the radio quality of SSBs transmitted by the network, and based on the measurements, the UE can select the SSB which is strongest, or better than a given threshold, in terms of radio quality such as, e.g. RSRP, Reference Signal Received Quality (RSRQ), Received Signal Strength Indicator (RSSI), Signal to Interference plus Noise Ratio (SINR), Signal to Interference Ratio (SIR) etc. The UE can then use the SRS configuration / SRS resource which is associated with / mapped to the selected SSB.

[0058] As noted above, in the embodiment of Fig. 1 the gNB sends an indication to start SRS transmissions to the UE in Msg4 110. However, in other embodiments, the SRS transmissions can be started autonomously by the UE, i.e. without Msg4 including a specific indication.

[0059] A UE may monitor one or more conditions to determine whether to start SRS transmissions, and start SRS transmissions if one or more of those conditions, or all condition(s), are satisfied. Thus, a UE can initiate SRS transmissions autonomously if one or more of the following conditions are satisfied:

[0060] • the data volume (e.g. the amount of the data of the radio bearers which are enabled for the SDT procedure) is above a threshold when initiating the SDT procedure;

[0061] • the data volume is above a threshold during the SDT procedure;

[0062] • when a Buffer Status Report (BSR) is triggered (noting that a BSR can be triggered when, for example, UL data for a logical channel which belongs to a Logical Channel Group (LCG) becomes available to the Medium Access Control (MAC) entity, and either (i) this UL data belongs to a logical channel with higher priority than the priority of any logical channel containing available UL data which belongs to any LCG; or (ii) none of the logical channels which belong to an LCG contain any available UL data);

[0063] • the data priority (e.g. the priority level associated with the logical channel containing the data) is above a threshold;

[0064] • the UE has a SRS configuration in UE context and the UE is camping in the same cell or on the same gNB where the UE was released to inactive and the UE is in a low mobility state (e.g. moving slowly or stationary). The UE being slow moving or stationary can be defined as the current RSRP being within a threshold of the RSRP the UE had when it was released, or it can be determined from the UE being in a low or medium mobility state.

[0065] In some embodiments, whether the UE can autonomously apply a stored SRS configuration / SRS resource can depend on the mobility state of the UE. In some cases, the UE may directly transmit using the stored SRS configuration or the SRS resource only when the UE is static or in a low (slow) moving state. A speed or velocity threshold may be configured to the UE. In this way, the UE can use the stored SRS configuration or the SRS resource only if the UE’s speed or velocity is below the configured threshold.

[0066] The UE may indicate its mobility state / status compared to when it was released to inactive mode to the gNB. In this case, reporting that the UE is stationary implies that the gNB can deduce that the UL channel conditions the UE had in connected mode are still valid and can select TB size and MCS accordingly.

[0067] In other embodiments, whether the UE can autonomously apply a stored SRS configuration / SRS resource can depend on whether the UE can maintain its UL synchronisation to the gNB via the last timing advance (TA) value configured / used when the UE was in a connected state. In particular, the UE can apply the stored SRS configuration / SRS resource if the UE can maintain its UL synchronisation to the gNB via the last TA value.

[0068] Alternatively, rather than trying to maintain UL synchronisation to the gNB via the last TA value, the UE may autonomously adjust its TA value with respect to the last configured / used TA value. The UE may adjust its TA value based on one or more of the following:

[0069] • the movement of the UE, leading to the changes of the propagation delay between the UE and the gNB;

[0070] • changes in the propagation paths, for example, some paths disappear, and some new ones arise, causing changes to the propagation delay;

[0071] • oscillator drift in the UE, where the accumulation of small frequency errors over time may result in timing errors; and

[0072] • Doppler shift arising from the movement of the UE, resulting in an additional frequency offset of the uplink signals received at gNB.

[0073] Based on any one or more of the above, or other criteria, the UE may itself estimate the possible TA adjustment. Generally, the TA adjustment should be in a small range compared to the last TA value so that the new TA value (i.e. the old TA value plus a TA adjustment value) shall be similar or not differ much compared to the last TA value. The UE can then apply the new TA value to its UL transmissions, and thereby maintain UL synchronisation. In this case, the UE can apply the stored SRS configuration or the SRS resource. In some embodiments, the gNB can configure the UE with a maximum TA adjustment that limits the adjustment the UE can apply to the old TA value in order to determine the new TA value and maintain UL synchronisation, and therefore allow the UE to apply a stored SRS configuration or a SRS resource.

[0074] As noted above, in the embodiment of Fig. 1 the gNB sends an indication to start SRS transmissions to the UE in Msg4 110. However, in an alternative embodiment, the gNB can send an indication to the UE to start SRS transmissions in the RA Response (Msg2) 106. In this case, contention resolution (CR) has not been performed so there is a risk of colliding UEs. In one option for this embodiment, the gNB can identify the UE based on the SRS transmission and can use the SRS transmission for the scheduling of Msg3 108. In another option where the UE cannot be identified from the SRS transmission and the UE does not succeed with CR, the UE should stop the SRS transmissions assuming the Physical Random Access Channel (PRACH) transmission has failed and does a new Random Access Channel (RACH) resource selection. In another option for this embodiment, the SRS transmissions are not started until after the CR, even though the SRS start indication is present in the RAR 106.

[0075] While in the embodiment shown in Fig. 1 , the indication to start SRS transmissions is given in Msg4 110 which also performs CR, in an alternative approach, the indication to start the SRS transmissions can be sent to the UE at any time after the CR. This indication can be in the form of a Medium Access Control (MAC) Control Element (CE) or in DCI. This approach can be used when the UE is using CG-SDT.

[0076] In further embodiments, the gNB can indicate to the UE to stop SRS transmissions. The indication can be in the form of a MAC CE or in DCI. This embodiment can be useful in case UEs are autonomously selecting SRS resources, or several UEs are configured to use the same SRS resources and a collision occurs, e.g. where two or more UEs are simultaneously transmitting on the same SRS resources. In this case the gNB can instruct one or several UEs to stop transmitting SRS.

[0077] A UE capability may be defined for indicating whether the UE supports transmission of SRS for SDT. The UE can report this capability to the gNB when the UE is in RRC_Connected. Based on this UE capability indication, the gNB can determine whether to allow / configure the UE to transmit SRS when the UE transitions to RRC INACTIVE state.

[0078] While the above embodiments are described with respect to the 4-step random access process comprising messages 1-4, it will be appreciated that the techniques described herein are also applicable to a 2-step RA procedure. In a 2-step RA procedure, the UE sends a message (MsgA) to the gNB that includes the RA preamble and the UL data. The gNB sends a RA response message (MsgB) to the UE. MsgA is effectively a combination of Msg1 and Msg3 in the 4-step RA process, and MsgB is effectively a combination of Msg2 and Msg4 in the 4-step process. As such, features in the above embodiments that are implemented in or using Msg1 and / or Msg3 can be implemented in or using MsgA in the 2-step RA process. Likewise, features in the above embodiments that are implemented in or using Msg2 and / or Msg4 can be implemented in or using MsgB in the 2-step RA process.

[0079] As noted above, while the techniques have been described and illustrated in terms of RA- SDT, they are also applicable to CG-SDT. In that case, with reference to Fig. 1 , the CG-SDT implementation would not include the preamble 104 or the response message 106. However, the UE transmits SDT data to the gNB in message 108 (also in the CG-SDT case message 108 is not Msg3 or MsgA of the RA procedure). The UE subsequently starts SRS transmissions for measurement by the gNB.

[0080] While the above embodiments have been described with respect to mobile originating (MO) SDT, i.e. where the UE initially has data to transmit to the network, it will be appreciated that the techniques described herein can be applied to mobile terminating (MT) SDT, where the initial data transmission is from the network to the UE, and the UE subsequently has UL data to transmit to the network. Fig. 2 is a timeline illustrating the signalling according to an exemplary embodiment of the techniques described herein for MT-SDT where the UE uses the 4-step RA in order to subsequently transmit uplink data. In this illustrated embodiment, similar to that shown in Fig. 1 , the reference signal configuration is provided in a RRC Release message, and the network (i.e. RAN node / gNB) sends an indication to the UE to start the reference signal transmissions.

[0081] Signals / transmissions in Fig. 2 that are common to Fig. 1 are given the same reference numerals.

[0082] Thus, in Fig. 2, signal 102 represents the release message (RRC_Release) that includes one or more SRS configurations that is sent to the UE by the gNB. The release message 102 is sent to the UE when the UE is released to an inactive state.

[0083] Subsequently, the network has DL data to send to the UE, and the network sends a paging message 202 to the UE. In some embodiments, the paging message can include the indication for the UE to start SRS transmissions, but in other embodiments the indication can be transmitted in a subsequent message.

[0084] Following receipt of the paging message 202, in this illustrated embodiment the UE initiates the 4-step RA process by sending a RA preamble 104 to the gNB, as in Fig. 1 . The gNB responds to the RA preamble 104 with a response message 106 (e.g. a Random Access Response (RAR)), also as in Fig. 1.

[0085] The UE can then send connection request message 204, e.g. Message 3 (Msg3) 204 of the 4-step RA procedure. Msg3 204 is sent resources allocated / scheduled by response message 106. Msg3 204 may be a RRC Connection Request message. If the UE has UL data to transmit at this stage, the UE can include this data in message 204, similar to message 108 in Fig. 1 .

[0086] The gNB then sends a message 206 to the UE in response to Msg3 204. This response 206 is Msg4 in the 4-step RA procedure, and therefore can be a RRC Connection Release message. In some embodiments, the response 206 activates the SRS transmissions according to the SRS configuration signalled in signal 102, and response 206 also effects contention resolution (CR). Thus, in these embodiments, on or after receiving response 206, the UE starts transmitting SRS according to the SRS configuration. In embodiments where the paging message 202 indicates to the UE that SRS transmission is to start, the UE may start SRS transmission after receiving the RAR 106, after transmitting Msg3 204, or after CR.

[0087] Now that the RA procedure is complete, the network can transmit the DL data to the UE. The DL data can be transmitted to the UE as part of message 206 that completes the RA procedure (i.e. as part of Msg4), or as part of a separate message / signal 208. If there is still DL data to transmit to the UE, the network may transmit further DL data using further instances of signal 208.

[0088] In common with the embodiment in Fig. 1 , the gNB measures the SRS transmitted by the UE and uses the measurements to schedule UL data transmissions by the UE. The gNB sends downlink control information (DCI) 112 to the UE that indicates the UL resources to be used by the UE to transmit UL data. Signals 114 represent the UL data transmitted by the UE using the scheduled resources.

[0089] Fig. 3 is a flow chart illustrating a method according to various embodiments. The method may be performed by a UE or wireless device in a communication network such as the UE 512 or UE 600 as described later with reference to Figs. 5 and 6 respectively. The UE may perform the method in response to executing suitably formulated computer readable code. The computer readable code may be embodied or stored on a computer readable medium, such as a memory chip, optical disc, or other storage medium. The computer readable medium may be part of a computer program product. In step 301 , the UE transmits data to, or receives data from, a first RAN node using a SDT procedure.

[0090] The SDT procedure used by the UE may be a MO-SDT procedure. In this case, step 301 comprises transmitting data to the first RAN node. The transmission of the data to the first RAN node may be part of a RA procedure, or a CG procedure.

[0091] Alternatively, the SDT procedure used by the UE may be a MT-SDT procedure. In this case, step 301 comprises receiving data from the first RAN node. Step 301 can be performed following receipt of a paging message (e.g. paging message 202) from the first RAN node.

[0092] In step 303, the UE transmits one or more reference signals for measurement by the first RAN node. The reference signals may be Sounding Reference Signals (SRS). Step 303 may be initiated by the UE, or initiated in response to an indication from the RAN node.

[0093] In embodiments where the SDT procedure is a MT-SDT procedure, the data can be received from the first RAN node in step 301 before or after the one or more reference signals are transmitted in step 303 (that is, step 303 may occur before step 301 , or vice versa).

[0094] In step 305, the UE receives a first indication from the first RAN node of one or more resources to be used for further data transmissions by the UE using the SDT procedure. The first indication can be received in DCI.

[0095] The method performed by the UE can further comprise transmitting further data to the first RAN node using the SDT procedure and the indicated one or more resources.

[0096] The method may also further comprise the UE receiving an indication from the first RAN node indicating that the UE is to stop transmitting reference signals. This indication can be sent from the first RAN node regardless of whether the UE or the first RAN node initiates the transmission of the reference signal(s).

[0097] The reference signal(s) may be transmitted in step 303 according to a reference signal configuration. The reference signal configuration can indicate one or more resources to be used for reference signal transmissions.

[0098] The UE may receive one or more reference signal configurations from a RAN node, or otherwise have one or more stored reference signal configurations.

[0099] In some embodiments, the UE may receive (from the RAN node) an indication of a reference signal configuration to use for transmitting the one or more reference signals. For example, the indication may indicate or identify one of the multiple reference signal configurations that the UE is to use in step 303. The reference signal configuration(s) and / or the indication of the reference signal configuration to use can be received from a RAN node in one of: a release message (e.g. message 102); a RRC release message (e.g. message 102); a RA message (e.g. RAR message 106); a RAR message (e.g. RAR message 106); or in SI that is broadcast by the RAN node. In other embodiments, the reference signal configuration that the UE transmits the one or more reference signals according to is the reference signal configuration used by the UE when it was last in a connected state (e.g. RRC_Connected) with respect to the communication network.

[0100] In embodiments where there are a plurality of reference signal configurations, the reference signal configurations can be mapped to respective SSBs. The reference signal(s) are transmitted in step 303 according to a reference signal configuration for which the mapped SSB has a measured radio quality that satisfies a radio quality condition. The radio quality can be any of RSRP, RSRQ, RSSI, SINR, and SIR.

[0101] As noted above, step 303 (transmitting the one or more reference signals) may be initiated by the UE or in response to an indication from the RAN node. In the former case, the UE autonomously decides / determines to start transmitting the reference signal(s), i.e. without instruction from the (or any) RAN node. For example, the UE can initiate the transmission of the one or more reference signals if one or more conditions are satisfied. Any suitable condition (or combination of conditions) can be evaluated to determine whether or not to start transmitting reference signal(s). The conditions can include or relate to any of: a volume of data to be transmitted by the UE, with the condition being satisfied if the volume is above a threshold; a BSR, with the condition being satisfied if a BSR is triggered; a priority of the data to be transmitted, with the condition being satisfied if the priority is above a threshold;

[0102] - whether the UE is camping in a same cell or on a same RAN node where the UE was last released to inactive, with the condition being satisfied if the UE is camping in the same cell (or on the same RAN node);

[0103] - whether the UE is camping in a same cell or on a same RAN node where the UE was last released to inactive and the UE is stationary or in a low mobility state, with the condition being satisfied if the UE is camping in the same cell (or on the same RAN node) and stationary or in a low mobility state; and

[0104] - whether the UE has uplink synchronisation with the first RAN node, with the condition being satisfied if the UE has uplink synchronisation.

[0105] If the UE has a stored reference signal configuration, the condition can be that the reference signal(s) are transmitted according to the stored reference signal configuration if the UE has uplink synchronisation with the first RAN node. In this approach, the UE can adjust a timing advance (TA) value to maintain uplink synchronisation with the first RAN node.

[0106] In embodiments where step 303 is performed in response to receiving an indication (referred to as a “second indication”) from the first RAN node, the indication can be part of a message received from the first RAN node in a RA procedure. The message may be Msg4 of a 4-step RA procedure, or MsgB of a 2-step RA procedure.

[0107] In alternative embodiments (although also where step 303 is performed in response to receiving the second indication from the first RAN node), the indication is received after a RA procedure has been completed and / or after a contention resolution procedure has been completed. In these embodiments, the second indication may be received in DCI or in a MAC CE.

[0108] Fig. 4 is a flow chart illustrating another method in accordance with particular embodiments. The method may be performed by a first RAN network node, such as the RAN network node 510 or RAN network node 700 as described later with reference to Fig. 5 and 7 respectively. The first RAN node may perform the method in response to executing suitably formulated computer readable code. The computer readable code may be embodied or stored on a computer readable medium, such as a memory chip, optical disc, or other storage medium. The computer readable medium may be part of a computer program product.

[0109] In step 401 , the first RAN node transmits data to, or receives data from, a UE using a SDT procedure.

[0110] The SDT procedure used by the UE may be a MO-SDT procedure. In this case, step 401 comprises receiving data from the UE. The data may be transmitted from the UE to the first RAN node as part of a RA procedure, or a CG procedure.

[0111] Alternatively, the SDT procedure used by the UE may be a MT-SDT procedure. In this case, step 401 comprises transmitting data to the UE. Step 401 can be performed following transmission of a paging message (e.g. paging message 202) from the first RAN node to the UE.

[0112] In step 403, the first RAN node measures one or more reference signals transmitted by the UE. The reference signals may be Sounding Reference Signals (SRS).

[0113] In embodiments where the SDT procedure is a MT-SDT procedure, the data can be transmitted by the first RAN node in step 401 before or after the one or more reference signals are measured in step 403 (that is, step 403 may occur before step 401 , or vice versa).

[0114] In step 405, the first RAN node determines one or more resources to be used for further data transmissions by the UE using the SDT procedure. The first RAN node determines the resource(s) based on the measurements of the one or more reference signals.

[0115] In step 407, the first RAN node sends a first indication to the UE of the one or more resources. The first indication can be sent in DCI.

[0116] The method performed by the first RAN node can further comprise receiving further data from the UE using the SDT procedure and the indicated one or more resources.

[0117] The method may also further comprise the first RAN node transmitting an indication to the UE indicating that the UE is to stop transmitting reference signals. This indication can be sent by the first RAN node regardless of whether the UE or the first RAN node initiates the transmission of the reference signal(s).

[0118] The reference signal(s) may be transmitted by the UE according to a reference signal configuration. That reference signal configuration can indicate one or more resources to be used for reference signal transmissions.

[0119] The first RAN node may send one or more reference signal configurations to the UE, or the UE may otherwise have one or more stored reference signal configurations.

[0120] In some embodiments, the first RAN node may send (to the UE) an indication of a reference signal configuration to use for transmitting the one or more reference signals. For example, the indication may indicate or identify one of the multiple reference signal configurations that the UE is to use to transmit the reference signal(s). The reference signal configuration(s) and / or the indication of the reference signal configuration to use can be transmitted from the RAN node to the UE in one of: a release message (e.g. message 102); a RRC release message (e.g. message 102); a RA message (e.g. RAR message 106); a RAR message (e.g. RAR message 106); or in SI that is broadcast by the RAN node.

[0121] The transmission of the reference signal(s) by the UE may be initiated by the UE, or in response to an indication from the RAN node. In this latter case, the first RAN node can transmit an indication (referred to as a “second indication”) to the UE. This second indication can be part of a message transmitted by the first RAN node in a RA procedure. The message may be Msg4 of a 4-step RA procedure, or MsgB of a 2-step RA procedure. Alternatively, the first RAN node can transmit the second indication after a RA procedure has been completed and / or after a contention resolution procedure has been completed. In these embodiments, the second indication may be transmitted in DCI or in a MAC CE.

[0122] UE 5 shows an example of a communication system 500 in accordance with some embodiments. In the example, the communication system 500 includes a telecommunication network 502 that includes an access network 504, such as a radio access network (RAN), and a core network 506, which includes one or more core network nodes 508. The access network 504 includes one or more access network nodes, such as access network nodes 510a and 510b (which are interchangeably referred to as RAN network nodes 510 herein), or any other similar 3rdGeneration Partnership Project (UE) access node or non-UE access point (AP). Moreover, as will be appreciated by those of skill in the art, a RAN network node is not necessarily limited to an implementation in which a radio portion and a baseband portion are supplied and integrated by a single vendor. Thus, it will be understood that network nodes include disaggregated implementations or portions thereof. For example, in some embodiments, the telecommunication network 502 includes one or more Open-RAN (ORAN) network nodes. An ORAN network node is a node in the telecommunication network 502 that supports an ORAN specification (e.g., a specification published by the O-RAN Alliance, or any similar organization) and may operate alone or together with other nodes to implement one or more functionalities of any node in the telecommunication network 502, including one or more network nodes 510 and / or core network nodes 508.

[0123] Examples of an ORAN network node include an open radio unit (0-Rll), an open distributed unit (O-DU), an open central unit (O-CU), including an O-CU control plane (O-CU-CP) or an O- Cll user plane (O-CU-UP), a RAN intelligent controller (RIC) (near-real time or non-real time) hosting software or software plug-ins, such as a near-real time control application (e.g., xApp) or a non-real time control application (e.g., rApp), or any combination thereof (the adjective “open” designating support of an ORAN specification). The network node may support a specification by, for example, supporting an interface defined by the ORAN specification, such as an A1 , F1 , W1 , E1 , E2, X2, Xn interface, an open fronthaul user plane interface, or an open fronthaul management plane interface. Moreover, an ORAN access node may be a logical node in a physical node. Furthermore, an ORAN network node may be implemented in a virtualization environment (described further below) in which one or more network functions are virtualized. For example, the virtualization environment may include an O-Cloud computing platform orchestrated by a Service Management and Orchestration Framework via an O-2 interface defined by the O-RAN Alliance or comparable technologies.

[0124] The access network nodes 510 facilitate direct or indirect connection of wireless devices (also referred to interchangeably herein as user equipment (UE)), such as by connecting UEs 512a, 512b, 512c, and 512d (one or more of which may be generally referred to as UEs 512) to the core network 506 over one or more wireless connections. The access network nodes 510 may be, for example, access points (APs) (e.g. radio access points), base stations (BSs) (e.g. radio base stations, Node UE, evolved Node UE (eNBs) and New Radio (NR) NodeBs (gNBs)).

[0125] Unless otherwise indicated, the general term ‘network node’ as used herein refers to access network nodes 510 and core network nodes 508.

[0126] Example wireless communications over a wireless connection include transmitting and / or receiving wireless signals using electromagnetic waves, radio waves, infrared waves, and / or other types of signals suitable for conveying information without the use of wires, cables, or other material conductors. Moreover, in different embodiments, the communication system 500 may include any number of wired or wireless networks, network nodes, UEs, and / or any other components or systems that may facilitate or participate in the communication of data and / or signals whether via wired or wireless connections. The communication system 500 may include and / or interface with any type of communication, telecommunication, data, cellular, radio network, and / or other similar type of system.

[0127] The wireless devices / UEs 512 may be any of a wide variety of communication devices, including wireless devices arranged, configured, and / or operable to communicate wirelessly with the network nodes 510 and other communication devices. Similarly, the access network nodes 510 are arranged, capable, configured, and / or operable to communicate directly or indirectly with the UEs 512 and / or with other network nodes or equipment in the telecommunication network 502 to enable and / or provide network access, such as wireless network access, and / or to perform other functions, such as administration in the telecommunication network 502.

[0128] In the depicted example, the core network 506 connects the access network nodes 510 to one or more hosts, such as host 516. These connections may be direct or indirect via one or more intermediary networks or devices. In other examples, network nodes may be directly coupled to hosts. The core network 506 includes one more core network nodes (e.g. core network node 508) that are structured with hardware and software components. Features of these components may be substantially similar to those described with respect to the wireless devices / UEs, access network nodes, and / or hosts, such that the descriptions thereof are generally applicable to the corresponding components of the core network node 508. Example core network nodes include functions of one or more of a Mobile Switching Center (MSC), Mobility Management Entity (UE), Home Subscriber Server (HSS), Access and Mobility Management Function (AMF), Session Management Function (UE), Authentication Server Function (AUSF), Subscription Identifier De-concealing function (SIDF), Unified Data Management (UE), Security Edge Protection Proxy (SEPP), Network Exposure Function (UE), and / or a User Plane Function (UE).

[0129] The host 516 may be under the ownership or control of a service provider other than an operator or provider of the access network 504 and / or the telecommunication network 502, and may be operated by the service provider or on behalf of the service provider. The host 516 may host a variety of applications to provide one or more services. Examples of such applications include the provision of live and / or pre-recorded audio / video content, data collection services, for example, retrieving and compiling data on various ambient conditions detected by a plurality of UEs, analytics functionality, social media, functions for controlling or otherwise interacting with remote devices, functions for an alarm and surveillance center, or any other such function performed by a server.

[0130] As a whole, the communication system 500 of UE 5 enables connectivity between the wireless devices / UEs, network nodes, and hosts. In that sense, the communication system may be configured to operate according to predefined rules or procedures, such as specific standards that include, but are not limited to: Global System for Mobile Communications (GSM); Universal Mobile Telecommunications System (UMTS); Long Term Evolution (UE), and / or other suitable 2ndGeneration (2G), 3rdGeneration (3G), 4thGeneration (4G), 5thGeneration (5G) standards, or any applicable future generation standard (e.g. 6thGeneration (6G)); wireless local area network (WLAN) standards, such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards (WiFi); and / or any other appropriate wireless communication standard, such as the Worldwide Interoperability for Microwave Access (WiMax), Bluetooth, Z-Wave, Near Field Communication (UE) ZigBee, LiFi, and / or any low-power wide-area network (LPWAN) standards such as LoRa and Sigfox.

[0131] In some examples, the telecommunication network 502 is a cellular network that implements UE standardized features. Accordingly, the telecommunications network 502 may support network slicing to provide different logical networks to different devices that are connected to the telecommunication network 502. For example, the telecommunications network 502 may provide Ultra Reliable Low Latency Communication (URLLC) services to some UEs, while providing Enhanced Mobile Broadband (eMBB) services to other UEs, and / or Massive Machine Type Communication (mMTC) / Massive Internet of Things (loT) services to yet further UEs.

[0132] In some examples, the UEs 512 are configured to transmit and / or receive information without direct human interaction. For instance, a UE may be designed to transmit information to the access network 504 on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the access network 504. Additionally, a UE may be configured for operating in single- or multi-radio access technology (RAT) or multi-standard mode. For example, a UE may operate with any one or combination of Wi-UE, NR (New Radio) and UE, i.e. being configured for multi-radio dual connectivity (MR-DC), such as E-UTRAN (Evolved- UTRA (UMTS Terrestrial Radio Access) Network) New Radio - Dual Connectivity (EN-DC).

[0133] In the example illustrated in UE 5, the hub 514 communicates with the access network 504 to facilitate indirect communication between one or more UEs (e.g. UE 512c and / or 512d) and access network nodes (e.g. access network node 510b). In some examples, the hub 514 may be a controller, router, a content source and analytics node, or any of the other communication devices described herein regarding UEs. For example, the hub 514 may be a broadband router enabling access to the core network 506 for the UEs. As another example, the hub 514 may be a controller that sends commands or instructions to one or more actuators in the UEs. Commands or instructions may be received from the UEs, network nodes 510, or by executable code, script, process, or other instructions in the hub 514. As another example, the hub 514 may be a data collector that acts as temporary storage for UE data and, in some embodiments, may perform analysis or other processing of the data. As another example, the hub 514 may be a content source. For example, for a UE that is a Virtual Reality VR headset, display, loudspeaker or other media delivery device, the hub 514 may retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, which the hub 514 then provides to the UE either directly, after performing local processing, and / or after adding additional local content. In still another example, the hub 514 acts as a proxy server or orchestrator for the UEs, in particular if one or more of the UEs are low energy Internet of Things (loT) devices.

[0134] The hub 514 may have a constant / persistent or intermittent connection to the network node 510b. The hub 514 may also allow for a different communication scheme and / or schedule between the hub 514 and UEs (e.g. UE 512c and / or 512d), and between the hub 514 and the core network 506. In other examples, the hub 514 is connected to the core network 506 and / or one or more UEs via a wired connection. Moreover, the hub 514 may be configured to connect to a Machine-to-Machine (M2M) service provider over the access network 504 and / or to another UE over a direct connection. In some scenarios, UEs may establish a wireless connection with the network nodes 510 while still connected via the hub 514 via a wired or wireless connection. In some embodiments, the hub 514 may be a dedicated hub - that is, a hub whose primary function is to route communications to / from the UEs from / to the network node 510b. In other embodiments, the hub 514 may be a non-dedicated hub - that is, a device which is capable of operating to route communications between the UEs and network node 510b, but which is additionally capable of operating as a communication start and / or end point for certain data channels.

[0135] UE 6 shows a wireless device or UE 600 in accordance with some embodiments. As used herein, a UE refers to a device capable, configured, arranged and / or operable to communicate wirelessly with network nodes and / or other UEs. Examples of a wireless device / UE include, but are not limited to, a smart phone, mobile phone, cell phone, voice over UE (VoIP) phone, wireless local loop phone, desktop computer, personal digital assistant (PDA), wireless camera, gaming console or device, music storage device, playback appliance, wearable terminal device, wireless endpoint, mobile station, tablet, laptop, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), smart device, wireless customer-premise equipment (CPE), vehicle, vehiclemounted or vehicle embedded / integrated wireless device, etc. Other examples include any UE identified by the 3rdGeneration Partnership Project (UE), including a narrow band internet of things (NB-loT) UE, a machine type communication (MTC) UE, and / or an enhanced MTC (eMTC) UE.

[0136] A wireless device / UE may support device-to-device (UE) communication, for example by implementing a UE standard for sidelink communication, Dedicated Short-Range Communication (DSRC), vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), or vehicle-to-everything (V2X). In other examples, a UE may not necessarily have a user in the sense of a human user who owns and / or operates the relevant device. Instead, a UE may represent a device that is intended for sale to, or operation by, a human user but which may not, or which may not initially, be associated with a specific human user (e.g. a smart sprinkler controller). Alternatively, a UE may represent a device that is not intended for sale to, or operation by, an end user but which may be associated with or operated for the benefit of a user (e.g. a smart power meter).

[0137] The UE 600 includes processing circuitry 602 that is operatively coupled via a bus 604 to an input / output interface 606, a power source 608, a memory 610, a communication interface 612, and / or any other component, or any combination thereof. Certain UEs may utilize all or a subset of the components shown in UE 6. The level of integration between the components may vary from one UE to another UE. Further, certain UEs may contain multiple instances of a component, such as multiple processors, memories, transceivers, transmitters, receivers, etc.

[0138] The processing circuitry 602 is configured to process instructions and data and may be configured to implement any sequential state machine operative to execute instructions stored as machine-readable computer programs in the memory 610. The processing circuitry 602 may be implemented as one or more hardware-implemented state machines (e.g. in discrete logic, field- programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), etc.); programmable logic together with appropriate firmware; one or more stored computer programs, general-purpose processors, such as a microprocessor or digital signal processor (DSP), together with appropriate software; or any combination of the above. For example, the processing circuitry 602 may include multiple central processing units (CPUs). The processing circuitry 602 may be operable to provide, either alone or in conjunction with other UE 600 components, such as the memory 610, to provide UE 600 functionality. For example, the processing circuitry 602 may be configured to cause the UE 602 to perform the methods as described with reference to UE 3.

[0139] In the example, the input / output interface 606 may be configured to provide an interface or interfaces to an input device, output device, or one or more input and / or output devices. Examples of an output device include a speaker, a sound card, a video card, a display, a monitor, a printer, an actuator, an emitter, a smartcard, another output device, or any combination thereof. An input device may allow a user to capture information into the UE 600. Examples of an input device include a touch-sensitive or presence-sensitive display, a camera (e.g. a digital camera, a digital video camera, a web camera, etc.), a microphone, a sensor, a mouse, a trackball, a directional pad, a trackpad, a scroll wheel, a smartcard, and the like. The presence-sensitive display may include a capacitive or resistive touch sensor to sense input from a user. A sensor may be, for instance, an accelerometer, a gyroscope, a tilt sensor, a force sensor, a magnetometer, an optical sensor, a proximity sensor, a biometric sensor, etc., or any combination thereof. An output device may use the same type of interface port as an input device. For example, a Universal Serial Bus (USB) port may be used to provide an input device and an output device.

[0140] In some embodiments, the power source 608 is structured as a battery or battery pack. Other types of power sources, such as an external power source (e.g. an electricity outlet), photovoltaic device, or power cell, may be used. The power source 608 may further include power circuitry for delivering power from the power source 608 itself, and / or an external power source, to the various parts of the UE 600 via input circuitry or an interface such as an electrical power cable. Delivering power may be, for example, for charging of the power source 608. Power circuitry may perform any formatting, converting, or other modification to the power from the power source 608 to make the power suitable for the respective components of the UE 600 to which power is supplied.

[0141] The memory 610 may be or be configured to include memory such as random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), magnetic disks, optical disks, hard disks, removable cartridges, flash drives, and so forth. In one example, the memory 610 includes one or more application programs 614, such as an operating system, web browser application, a widget, gadget engine, or other application, and corresponding data 616. The memory 610 may store, for use by the UE 600, any of a variety of various operating systems or combinations of operating systems.

[0142] The memory 610 may be configured to include a number of physical drive units, such as redundant array of independent disks (RAID), flash memory, USB flash drive, external hard disk drive, thumb drive, pen drive, key drive, high-density digital versatile disc (HD-DVD) optical disc drive, internal hard disk drive, Blu-Ray optical disc drive, holographic digital data storage (HDDS) optical disc drive, external mini-dual in-line memory module (DIMM), synchronous dynamic random access memory (SDRAM), external micro-DIMM SDRAM, smartcard memory such as tamper resistant module in the form of a universal integrated circuit card (UE) including one or more subscriber identity modules (SIMs), such as a Universal Subscriber Identity Module (USIM) and / or integrated SIM (ISIM), other memory, or any combination thereof. The UE may for example be an embedded UE (eUlCC), integrated UE (iUICC) or a removable UE commonly known as ‘SIM card.’ The memory 610 may allow the UE 600 to access instructions, application programs and the like, stored on transitory or non-transitory memory media, to off-load data, or to upload data. An article of manufacture, such as one utilizing a communication system may be tangibly embodied as or in the memory 610, which may be or comprise a device-readable storage medium.

[0143] The UEessing circuitry 602 may be configured to communicate with an access network or other network using the communication interface 612. The communication interface 612 may comprise one or more communication subsystems and may include or be communicatively coupled to an antenna 622. The communication interface 612 may include one or more transceivers used to communicate, such as by communicating with one or more remote transceivers of another device capable of wireless communication (e.g. another UE or a network node in an access network). Each transceiver may include a transmitter 618 and / or a receiver 620 appropriate to provide network communications (e.g. optical, electrical, frequency allocations, and so forth). Moreover, the transmitter 618 and receiver 620 may be coupled to one or more antennas (e.g. antenna 622) and may share circuit components, software or firmware, or alternatively be implemented separately.

[0144] In some embodiments, communication functions of the communication interface 612 may include cellular communication, Wi-LIE communication, LPWAN communication, data communication, voice communication, multimedia communication, short-range communications such as Bluetooth, near-field communication, location-based communication such as the use of the global positioning system (GPS) or other Global Navigation Satellite System (UE) to determine a location, another like communication function, or any combination thereof. Communications may be implemented in according to one or more communication protocols and / or standards, such as IEEE 802.11 , Code Division Multiplexing Access (CDMA), Wideband Code Division Multiple Access (WCDMA), GSM, UE, NR, UMTS, WiMax, Ethernet, transmission control protocol / internet protocol (TCP / UE), synchronous optical networking (SONET), Asynchronous Transfer Mode (ATM), QUIC, Hypertext Transfer Protocol (HTTP), and so forth.

[0145] Regardless of the type of sensor, a UE may provide an output of data captured by its sensors, through its communication interface 612, via a wireless connection to a network node. Data captured by sensors of a UE can be communicated through a wireless connection to a network node via another UE. The output may be periodic (e.g. once every 15 minutes if it reports the sensed temperature), random (e.g. to even out the load from reporting from several sensors), in response to a triggering event (e.g. when moisture is detected an alert is sent), in response to a request (e.g. a user initiated request), or a continuous stream (e.g. a live video feed of a patient).

[0146] As another example, a UE comprises an actuator, a motor, or a switch, related to a communication interface configured to receive wireless input from a network node via a wireless connection. In response to the received wireless input the states of the actuator, the motor, or the switch may change. For example, the UE may comprise a motor that adjusts the control surfaces or rotors of a drone in flight according to the received input or controls a robotic arm performing a medical procedure according to the received input.

[0147] A UE, when in the form of an loT device, may be a device for use in one or more application domains, these domains comprising, but not limited to, city wearable technology, extended industrial application and healthcare. Non-limiting examples of such an loT device are devices which are or which are embedded in: a connected refrigerator or freezer, a TV, a connected lighting device, an electricity meter, a robot vacuum cleaner, a voice controlled smart speaker, a home security camera, a motion detector, a thermostat, a smoke detector, a door / window sensor, a flood / moisture sensor, an electrical door lock, a connected doorbell, an air conditioning system like a heat pump, an autonomous vehicle, a surveillance system, a weather monitoring device, a vehicle parking monitoring device, an electric vehicle charging station, a smart watch, a fitness tracker, a head-mounted display for Augmented Reality (AR) or VR, a wearable for tactile augmentation or sensory enhancement, a water sprinkler, an animal- or item-tracking device, a sensor for monitoring a plant or animal, an industrial robot, an Unmanned Aerial Vehicle (UAV), and any kind of medical device, like a heart rate monitor or a remote controlled surgical robot. A UE in the form of an loT device comprises circuitry and / or software in dependence on the intended application of the loT device in addition to other components as described in relation to the UE 600 shown in UE 6.

[0148] As yet another specific example, in an loT scenario, a UE may represent a machine or other device that performs monitoring and / or measurements, and transmits the results of such monitoring and / or measurements to another UE and / or a network node. The UE may in this case be an M2M device, which may in a UE context be referred to as an MTC device. As one particular example, the UE may implement the UE NB-loT standard. In other scenarios, a UE may represent a vehicle, such as a car, a bus, a truck, a ship and an airplane, or other equipment that is capable of monitoring and / or reporting on its operational status or other functions associated with its operation.

[0149] In practice, any number of UEs may be used together with respect to a single use case. For example, a first UE might be or be integrated in a drone and provide the drone’s speed information (obtained through a speed sensor) to a second UE that is a remote controller operating the drone. When the user makes changes from the remote controller, the first UE may adjust the throttle on the drone (e.g. by controlling an actuator) to increase or decrease the drone’s speed. The first and / or the second UE can also include more than one of the functionalities described above. For example, a UE might comprise the sensor and the actuator, and handle communication of data for both the speed sensor and the actuators.

[0150] UE 7 shows an access network node 700 or RAN network node 700 in accordance with some embodiments. As used herein, access network node or RAN network node refers to equipment capable, configured, arranged and / or operable to communicate directly or indirectly with a UE and / or with other RAN network nodes or equipment or core network nodes, in a telecommunication network. Examples of access network nodes include, but are not limited to, access network nodes such as APs (e.g. radio access points), base stations (BSs) (e.g. radio base stations, Node UE, evolved Node UE (eNBs) and NR NodeBs (gNBs)), Open RAN (O-RAN) nodes or components of an O-RAN node (e.g., 0-Rll, 0-Dll, O-CU).

[0151] Base stations may be categorized based on the amount of coverage they provide (or, stated differently, their transmit power level) and so, depending on the provided amount of coverage, may be referred to as femto base stations, pico base stations, micro base stations, or macro base stations. A base station may be a relay node or a relay donor node controlling a relay. A RAN network node may also include one or more (or all) parts of a distributed radio base station such as centralized digital units, distributed units (e.g., in an O-RAN access node), and / or remote radio units (RRUs), sometimes referred to as Remote Radio Heads (RRHs). Such remote radio units may or may not be integrated with an antenna as an antenna integrated radio. Parts of a distributed radio base station may also be referred to as nodes in a distributed antenna system (DAS).

[0152] Other examples of access network nodes include multiple transmission point (multi-TRP) 5G access nodes, multi-standard radio (MSR) equipment such as MSR BSs, network controllers such as radio network controllers (RNCs) or base station controllers (BSCs), base transceiver stations (BTSs), transmission points, transmission nodes, multi-cell / multicast coordination entities (MCEs), Operation and Maintenance (O&M) nodes, Operations Support System (OSS) nodes, Self-Organizing Network (SON) nodes, positioning nodes (e.g. Evolved Serving Mobile Location Centers (E-SMLCs)), and / or Minimization of Drive Tests (MDTs).

[0153] The RAN network node 700 includes processing circuitry 702, a memory 704, a communication interface 706, and a power source 708, and / or any other component, or any combination thereof. The RAN network node 700 may be composed of multiple physically separate components (e.g. a NodeB component and a RNC component, or a BTS component and a BSC component, etc.), which may each have their own respective components. In certain scenarios in which the RAN network node 700 comprises multiple separate components (e.g. BTS and BSC components), one or more of the separate components may be shared among several network nodes. For example, a single RNC may control multiple NodeBs. In such a scenario, each unique NodeB and RNC pair, may in some instances be considered a single separate network node. In some embodiments, the RAN network node 700 may be configured to support multiple radio access technologies (RATs). In such embodiments, some components may be duplicated (e.g. separate memory 704 for different RATs) and some components may be reused (e.g. a same antenna 710 may be shared by different RATs). The RAN network node 700 may also include multiple sets of the various illustrated components for different wireless technologies integrated into RAN network node 700, for example GSM, WCDMA, UE, NR, WiFi, Zigbee, Z-wave, LoRaWAN, Radio Frequency Identification (RFID) or Bluetooth wireless technologies. These wireless technologies may be integrated into the same or different chip or set of chips and other components within RAN network node 700.

[0154] The UEessing UErcuitry 702 may comprise a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application-specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, software and / or encoded logic operable to provide, either alone or in conjunction with other RAN network node 700 components, such as the memory 704, to provide network node 700 functionality. For example, the processing circuitry 702 may be configured to cause the RAN network node to perform the methods as described with reference to UE 4.

[0155] In some embodiments, the processing circuitry 702 includes a system on a chip (SOC). In some embodiments, the processing circuitry 702 includes one or more of radio frequency (UE) transceiver circuitry 712 and baseband processing circuitry 714. In some embodiments, the radio frequency (UE) transceiver circuitry 712 and the baseband processing circuitry 714 may be on separate chips (or sets of chips), boards, or units, such as radio units and digital units. In alternative embodiments, part or all of UE transceiver circuitry 712 and baseband processing circuitry 714 may be on the same chip or set of chips, boards, or units.

[0156] The memory 704 may comprise any form of volatile or non-volatile computer-readable memory including, without limitation, persistent storage, solid-state memory, remotely mounted memory, magnetic media, optical media, random access memory (RAM), read-only memory (ROM), mass storage media (for example, a hard disk), removable storage media (for example, a flash drive, a Compact Disk (UE) or a Digital Video Disk (DVD)), and / or any other volatile or non-volatile, non-transitory device-readable and / or computer-executable memory devices that store information, data, and / or instructions that may be used by the processing circuitry 702. The memory 704 may store any suitable instructions, data, or information, including a computer program, software, an application including one or more of logic, rules, code, tables, and / or other instructions capable of being executed by the processing circuitry 702 and utilized by the RAN network node 700. The memory 704 may be used to store any calculations made by the processing circuitry 702 and / or any data received via the communication interface 706. In some embodiments, the processing circuitry 702 and memory 704 is integrated.

[0157] The communication interface 706 is used in wired or wireless communication of signalling and / or data between network nodes, the access network, the core network, and / or a UE. As illustrated, the communication interface 706 comprises port(s) / terminal(s) 716 to send and receive data, for example to and from a network over a wired connection.

[0158] The communication interface 706 also includes radio front-end circuitry 718 that may be coupled to, or in certain embodiments a part of, the antenna 710. Radio front-end circuitry 718 comprises filters 720 and amplifiers 722. The radio front-end circuitry 718 may be connected to an antenna 710 and processing circuitry 702. The radio front-end circuitry may be configured to condition signals communicated between antenna 710 and processing circuitry 702. The radio front-end circuitry 718 may receive digital data that is to be sent out to other network nodes or UEs via a wireless connection. The radio front-end circuitry 718 may convert the digital data into a radio signal having the appropriate channel and bandwidth parameters using a combination of filters 720 and / or amplifiers 722. The radio signal may then be transmitted via the antenna 710. Similarly, when receiving data, the antenna 710 may collect radio signals which are then converted into digital data by the radio front-end circuitry 718. The digital data may be passed to the processing circuitry 702. In other embodiments, the communication interface may comprise different components and / or different combinations of components.

[0159] In certain alternative embodiments, the access network node 700 does not include separate radio front-end circuitry 718, instead, the processing circuitry 702 includes radio front-end circuitry and is connected to the antenna 710. Similarly, in some embodiments, all or some of the UE transceiver circuitry 712 is part of the communication interface 706. In still other embodiments, the communication interface 706 includes one or more ports or terminals 716, the radio front-end circuitry 718, and the UE transceiver circuitry 712, as part of a radio unit (not shown), and the communication interface 706 communicates with the baseband processing circuitry 714, which is part of a digital unit (not shown).

[0160] The antenna 710 may include one or more antennas, or antenna arrays, configured to send and / or receive wireless signals. The antenna 710 may be coupled to the radio front-end circuitry 718 and may be any type of antenna capable of transmitting and receiving data and / or signals wirelessly. In certain embodiments, the antenna 710 is separate from the network node 700 and connectable to the RAN network node 700 through an interface or port.

[0161] The antenna 710, communication interface 706, and / or the processing circuitry 702 may be configured to perform any receiving operations and / or certain obtaining operations described herein as being performed by the network node. Any information, data and / or signals may be received from a UE, another network node and / or any other network equipment. Similarly, the antenna 710, the communication interface 706, and / or the processing circuitry 702 may be configured to perform any transmitting operations described herein as being performed by the network node. Any information, data and / or signals may be transmitted to a UE, another network node and / or any other network equipment. The power source 708 provides power to the various components of RAN network node 700 in a form suitable for the respective components (e.g. at a voltage and current level needed for each respective component). The power source 708 may further comprise, or be coupled to, power management circuitry to supply the components of the network node 700 with power for performing the functionality described herein. For example, the RAN network node 700 may be connectable to an external power source (e.g. the power grid, an electricity outlet) via an input circuitry or interface such as an electrical cable, whereby the external power source supplies power to power circuitry of the power source 708. As a further example, the power source 708 may comprise a source of power in the form of a battery or battery pack which is connected to, or integrated in, power circuitry. The battery may provide backup power should the external power source fail.

[0162] Embodiments of the RAN network node 700 may include additional components beyond those shown in UE 7 for providing certain aspects of the network node’s functionality, including any of the functionality described herein and / or any functionality necessary to support the subject matter described herein. For example, the RAN network node 700 may include user interface equipment to allow input of information into the RAN network node 700 and to allow output of information from the RAN network node 700. This may allow a user to perform diagnostic, maintenance, repair, and other administrative functions for the RAN network node 700.

[0163] UE 8 is a block diagram illustrating a virtualization environment 800 in which functions implemented by some embodiments may be virtualized. In the present context, virtualizing means creating virtual versions of apparatuses or devices which may include virtualizing hardware platforms, storage devices and networking resources. As used herein, virtualization can be applied to any device described herein, or components thereof, and relates to an implementation in which at least a portion of the functionality is implemented as one or more virtual components. Some or all of the functions described herein may be implemented as virtual components executed by one or more virtual machines (VMs) implemented in one or more virtual environments 800 hosted by one or more of hardware nodes, such as a hardware computing device that operates as an access network node, a wireless device / UE, a core network node, or host. Further, in embodiments in which the virtual node does not require radio connectivity (e.g. a core network node or host), then the node may be entirely virtualized. In some embodiments, the virtualization environment 800 includes components defined by the Open-RAN (O-RAN) Alliance, such as an O-Cloud environment orchestrated by a Service Management and Orchestration Framework via an O-2 interface.

[0164] Applications 802 (which may alternatively be called software instances, virtual appliances, network functions, virtual nodes, virtual network functions, etc.) are run in the virtualization environment 800 to implement some of the features, functions, and / or benefits of some of the embodiments disclosed herein.

[0165] Hardware 804 includes processing circuitry, memory that stores software and / or instructions executable by hardware processing circuitry, and / or other hardware devices as described herein, such as a network interface, input / output interface, and so forth. Software may be executed by the processing circuitry to instantiate one or more virtualization layers 806 (also referred to as hypervisors or virtual machine monitors (VMMs)), provide VMs 808a and 808b (one or more of which may be generally referred to as VMs 808), and / or perform any of the functions, features and / or benefits described in relation with some embodiments described herein. The virtualization layer 806 may present a virtual operating platform that appears like networking hardware to the VMs 808.

[0166] The VMs 808 comprise virtual processing, virtual memory, virtual networking or interface and virtual storage, and may be run by a corresponding virtualization layer 806. Different embodiments of the instance of a virtual appliance 802 may be implemented on one or more of VMs 808, and the implementations may be made in different ways. Virtualization of the hardware is in some contexts referred to as network function virtualization (NFV). NFV may be used to consolidate many network equipment types onto industry standard high volume server hardware, physical switches, and physical storage, which can be located in data centers, and customer premise equipment.

[0167] In the context of NFV, a VM 808 may be a software implementation of a physical machine that runs programs as if they were executing on a physical, non-virtualized machine. Each of the VMs 808, and that part of hardware 804 that executes that VM, be it hardware dedicated to that VM and / or hardware shared by that VM with others of the VMs, forms separate virtual network elements. Still in the context of NFV, a virtual network function is responsible for handling specific network functions that run in one or more VMs 808 on top of the hardware 804 and corresponds to the application 802.

[0168] Hardware 804 may be implemented in a standalone network node with generic or specific components. Hardware 804 may implement some functions via virtualization. Alternatively, hardware 804 may be part of a larger cluster of hardware (e.g. such as in a data center or CPE) where many hardware nodes work together and are managed via management and orchestration 810, which, among others, oversees lifecycle management of applications 802. In some embodiments, hardware 804 is coupled to one or more radio units that each include one or more transmitters and one or more receivers that may be coupled to one or more antennas. Radio units may communicate directly with other hardware nodes via one or more appropriate network interfaces and may be used in combination with the virtual components to provide a virtual node with radio capabilities, such as a radio access node or a base station. In some embodiments, some signalling can be provided with the use of a control system 812 which may alternatively be used for communication between hardware nodes and radio units.

[0169] Although the computing devices described herein (e.g. UEs, RAN network nodes, core network node, hosts) may include the illustrated combination of hardware components, other embodiments may comprise computing devices with different combinations of components. It is to be understood that these computing devices may comprise any suitable combination of hardware and / or software needed to perform the tasks, features, functions and methods disclosed herein. Determining, calculating, obtaining or similar operations described herein may be performed by processing circuitry, which may process information by, for example, converting the obtained information into other information, comparing the obtained information or converted information to information stored in the network node, and / or performing one or more operations based on the obtained information or converted information, and as a result of said processing making a determination. Moreover, while components are depicted as single boxes located within a larger box, or nested within multiple boxes, in practice, computing devices may comprise multiple different physical components that make up a single illustrated component, and functionality may be partitioned between separate components. For example, a communication interface may be configured to include any of the components described herein, and / or the functionality of the components may be partitioned between the processing circuitry and the communication interface. In another example, non-computationally intensive functions of any of such components may be implemented in software or firmware and computationally intensive functions may be implemented in hardware.

[0170] In certain embodiments, some or all of the functionality described herein may be provided by processing circuitry executing instructions stored on in memory, which in certain embodiments may be a computer program product in the form of a non-transitory computer-readable storage medium. In alternative embodiments, some or all of the functionality may be provided by the processing circuitry without executing instructions stored on a separate or discrete device- readable storage medium, such as in a hard-wired manner. In any of those particular embodiments, whether executing instructions stored on a non-transitory computer-readable storage medium or not, the processing circuitry can be configured to perform the described functionality. The benefits provided by such functionality are not limited to the processing circuitry alone or to other components of the computing device, but are enjoyed by the computing device as a whole, and / or by end users and a wireless network generally.

[0171] The foregoing merely illustrates the principles of the disclosure. Various modifications and alterations to the described embodiments will be apparent to those skilled in the art in view of the teachings herein. It will thus be appreciated that those skilled in the art will be able to devise numerous systems, arrangements, and procedures that, although not explicitly shown or described herein, embody the principles of the disclosure and can be thus within the scope of the disclosure. Various exemplary embodiments can be used together with one another, as well as interchangeably therewith, as should be understood by those having ordinary skill in the art.

Claims

Claims1. A method performed by a user equipment, UE, in a communication network, the method comprising: transmitting (301) data to, or receiving data from, a first Radio Access Network, RAN, node using a Small Data Transmission, SDT, procedure; transmitting (303) one or more reference signals for measurement by the first RAN node; and receiving (305) a first indication from the first RAN node of one or more resources to be used for further data transmissions by the UE using the SDT procedure.

2. The method of claim 1 , wherein the method further comprises: transmitting further data to the first RAN node using the SDT procedure and the indicated one or more resources.

3. The method of claim 1 or 2, wherein the one or more reference signals are transmitted according to a reference signal configuration.

4. The method of claim 3, wherein the reference signal configuration indicates one or more resources to be used for reference signal transmissions.

5. The method of claim 3 or 4, wherein one or more reference signal configurations, and / or an indication of a reference signal configuration to use for transmitting the one or more reference signals, are received from a RAN node.

6. The method of claim 5, wherein the one or more reference signal configurations and / or the indication of the reference signal configuration to use are received from a RAN node in one of: a release message; a Radio Resource Control, RRC, release message; a Random Access, RA, message; a Random Access Response, RAR, message; or in System Information, SI.

7. The method of claim 3 or 4, wherein the reference signal configuration is a reference signal configuration used by the UE when last in a connected state with respect to the communication network.

8. The method of any of claims 3-7, wherein a plurality of reference signal configurations are mapped to respective Synchronisation Signal Blocks, SSBs.

9. The method of claim 8, wherein the one or more reference signals are transmitted according to a reference signal configuration for which the mapped SSB has a measured radio quality that satisfies a radio quality condition.

10. The method of any of claims 1-9, wherein the step of transmitting (303) the one or more reference signals is initiated by the UE.

11. The method of claim 10, wherein the UE initiates the transmission of the one or more reference signals if one or more conditions are satisfied.

12. The method of claim 11, wherein the one or more conditions are satisfied if any one or more of: a volume of data to be transmitted by the UE is above a threshold; a Buffer Status Report, BSR, is triggered; a priority of the data to be transmitted is above a threshold; the UE is camping in a same cell or on a same RAN node where the UE was last released to inactive; the UE is camping in a same cell or on a same RAN node where the UE was last released to inactive and the UE is stationary or in a low mobility state; and the UE has uplink synchronisation with the first RAN node.

13. The method of claim 10, wherein the UE has a stored reference signal configuration and wherein the one or more reference signals are transmitted according to the stored reference signal configuration provided that the UE has uplink synchronisation with the first RAN node.

14. The method of claim 13, wherein the UE adjusts a timing advance, TA, value to maintain uplink synchronisation with the first RAN node.

15. The method of any of claims 1-9, wherein the step of transmitting (303) the one or more reference signals is performed in response to receiving a second indication from the first RAN node.

16. The method of claim 15, wherein the second indication from the first RAN node is part of a message received from the first RAN node in a Random Access, RA, procedure.

17. The method of claim 16, wherein the message is Message 4, Msg4, of a 4-step RA procedure, or Message B, MsgB, of a 2-step RA procedure.

18. The method of claim 15, wherein the second indication from the first RAN node is received after a Random Access, RA, procedure has been completed, and / or after a contention resolution procedure has been completed.

19. The method of claim 18, wherein the second indication is received in Downlink Control Information, DCI, or in a Medium Access Control, MAC, Control Element, CE.

20. The method of any of claims 1-19, wherein the method further comprises: receiving a third indication from the first RAN node indicating that the UE is to stop transmitting reference signals.21 . The method of any of claims 1-20, wherein the reference signals are Sounding Reference Signals, SRS.

22. The method of any of claims 1-21 , wherein the first indication from the first RAN node of one or more resources to be used for further data transmissions by the UE is received in Downlink Control Information, DCI.

23. The method of any of claims 1-22, wherein the SDT procedure used by the UE is a Mobile Originating SDT, MO-SDT, procedure.

24. The method of claim 23, wherein the step of transmitting data to the first RAN node is performed as part of a Random Access, RA, procedure.

25. The method of claim 23, wherein the step of transmitting data to the first RAN node is performed as part of a Configured Grant, CG, procedure.

26. The method of any of claims 1-22, wherein the SDT procedure used by the UE is a Mobile Terminating SDT, MT-SDT, procedure.

27. The method of claim 26, wherein the step of receiving data (301) from the first RAN node is performed following receipt of a paging message from the first RAN node.

28. The method of claim 26 or 27, wherein the step of receiving data (301) from the first RAN node is performed before or after the step of transmitting one or more reference signals.

29. A method performed by a first Radio Access Network, RAN, node in a communication network, the method comprising: transmitting (401) data to, or receiving data from, a user equipment, UE, using a Small Data Transmission, SDT, procedure; measuring (403) one or more reference signals transmitted by the UE; determining (405), based on the measurements of the one or more reference signals, one or more resources to be used for further data transmissions by the UE using the SDT procedure; and sending (407) a first indication to the UE of the one or more resources.

30. The method of claim 29, wherein the method further comprises: receiving further data from the UE using the SDT procedure and the indicated one or more resources.31 . The method of claim 29 or 30, wherein the one or more reference signals are transmitted by the UE according to a reference signal configuration.

32. The method of claim 31 , wherein the reference signal configuration indicates one or more resources to be used for reference signal transmissions.

33. The method of claim 31 or 32, wherein the method further comprises: transmitting, to the UE, one or more reference signal configurations, and / or an indication of a reference signal configuration to use for transmitting the one or more reference signals.

34. The method of claim 33, wherein the one or more reference signal configurations and / or the indication of the reference signal configuration to use are transmitted to the UE in one of: a release message; a Radio Resource Control, RRC, release message; a Random Access, RA, message; a Random Access Response, RAR, message; or in System Information, SI.

35. The method of claim 31 or 32, wherein the reference signal configuration is a reference signal configuration used by the UE when last in a connected state with respect to the communication network.

36. The method of any of claims 31-35, wherein a plurality of reference signal configurations are mapped to respective Synchronisation Signal Blocks, SSBs.

37. The method of embodiment 36, wherein the one or more reference signals are transmitted according to a reference signal configuration for which the mapped SSB has a measured radio quality that satisfies a radio quality condition.

38. The method of any of claims 29-37, wherein the transmission of the one or more reference signals is initiated by the UE.

39. The method of any of claims 29-37, wherein the method further comprises: transmitting a second indication to the UE to initiate the transmission of the one or more reference signals by the UE.

40. The method of claim 39, wherein the second indication is transmitted as part of a message in a Random Access, RA, procedure.

41. The method of claim 40, wherein the message is Message 4, Msg4, of a 4-step RA procedure, or Message B, MsgB, of a 2-step RA procedure.

42. The method of claim 39, wherein the second indication is transmitted after a Random Access, RA, procedure has been completed, and / or after a contention resolution procedure has been completed.

43. The method of claim 42, wherein the second indication is sent in Downlink Control Information, DCI, or in a Medium Access Control, MAC, Control Element, CE.

44. The method of any of claims 29-43, wherein the method further comprises: sending a third indication to the UE indicating that the UE is to stop transmitting reference signals.

45. The method of any of claims 29-44, wherein the reference signals are Sounding Reference Signals, SRS.

46. The method of any of claims 29-45, wherein the first indication of one or more resources to be used for further data transmissions by the UE is sent in Downlink Control Information, DCI.

47. The method of any of claims 29-46, wherein the SDT procedure used is part of a Mobile Originating SDT, MO-SDT, procedure.

48. The method of claim 47, wherein the step of receiving data (401) from the UE is performed as part of a Random Access, RA, procedure.

49. The method of claim 47, wherein the step of receiving data (401) from the UE is performed as part of a Configured Grant, CG, procedure.

50. The method of any of claims 29-49, wherein the SDT procedure used is part of a Mobile Terminating SDT, MT-SDT, procedure.

51. The method of claim 50, wherein the step of transmitting data to the UE is performed following the transmission a paging message to the UE.

52. The method of claim 50 or 51 , wherein the step of transmitting data to the UE is performed before or after the step of measuring the one or more reference signals.

53. A computer program product comprising a computer readable medium having computer readable code embodied therein, the computer readable code being configured such that, on execution by a suitable computer or processor, the computer or processor is caused to perform the method of any of claims 1-52.

54. A user equipment, UE, configured to perform the method of any of claims 1-28.

55. A user equipment, UE, comprising a processor and a memory, said memory containing instructions executable by said processor whereby said UE is operative to perform the method of any of claims 1-28.

56. A first radio access network, RAN, node, configured to perform the method of any of claims 29-52.

57. A first radio access network, RAN, node comprising a processor and a memory, said memory containing instructions executable by said processor whereby said first RAN node is operative to perform the method of any of claims 29-52.

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