Method for apparatus for configuring a connection in a network

Abstract

A user equipment (UE) comprising: a transmitter; a receiver; and at least one processor configured to: receive, from a first network entity associated with at least one first cell, configuration infor

Description

Method and Apparatus for Configuring a Connection in a Network BACKGROUND Field

[0001] Certain examples of the present disclosure relate to methods, apparatus and / or systems for establishing or configuring carrier aggregation and / or dual connectivity in a network. In particular, in various examples the network is a Air-to-Ground network or a Non-Terrestrial Network. In various examples, SCell addition for a UE in the network is described. In various examples, SCG addition for a UE in the network is described. Other examples include methods and / or apparatus in which a UE transmits timing advance information in the network, where carrier aggregation and / or dual connectivity is configured for the UE. Various examples disclose an enhanced timing advance report MAC CE transmitted by the UE. In various examples, there is provided a Koffset MAC CE. Description of Related Art

[0002] The content of the following documents is referred to below and / or their content provides background information that the following disclosure should be considered in the context of: [1 ] 3GPP TS 38.331 - 5G; NR; Radio Resource Control (RRC); Protocol specification, Release 18 (e.g., V18.0.0). [2] 3GPP RP-221369 - CMCC, “Revised WID on Air-to-ground network for NR"; 3GPP TSG RAN Meeting #96; Budapest, Hungary, June 6-9, 2022. [3] 3GPP RP-211557 - Thales, “Solutions for NR to support nonterrestrial networks (NTN)"; 3GPP TSG RAN meeting #91-e; e-meeting, March 22 - 26th, 2021. [4] 3GPP RP-202689 - MediaTek Inc., “New Study WID on NB-loT / eTMC support for NTN’; 3GPP TSG RAN Meeting #90; Electronic Meeting, December? - 11,2020. [5] 3GPP RP-220953 - Thales, “NR NTN (Non-Terrestrial Networks) enhancements"; 3GPP TSG RAN Meeting #95e; Electronic Meeting, March 17-23,2022. [6] 3GPP RP-220979 - MediaTek Inc., “Revised WID on loTNTN enhancements"-, 3GPP TSG RAN Meeting #95e; Electronic Meeting, March 17-23,2022. [7] 3GPP RP-222654 - Thales, “Revised WID: NR NTN (NonTerrestrial Networks) enhancements"; 3GPP TSG RAN Meeting #97-e; e-meeting, September 12-16, 2022. [8] 3GPP RP-240839 - Moderator (Apple), “New WID on Enhancements for Air-to-ground network for NR; 3GPP TSG RAN Meeting #103; Maastricht, Netherlands, March 18-21,2024. Note: indicated version numbers are provided for illustrative purposes, other (including future) versions of these documents are considered also.

[0003] Wireless or mobile (cellular) communications networks in which a mobile terminal (e.g., user equipment (UE), such as a mobile handset) communicates via a radio link with a network of base stations (BSs), or other wireless access points (APs) or nodes, have undergone rapid development through a number of generations. The 3rd Generation Partnership Project (3GPP) design, specify and standardise technologies for mobile wireless communication networks. Fourth Generation (4G) and Fifth Generation (5G) systems (5GS) are now widely deployed, while beyond 5G (B5G) and 6G systems are being considered.

[0004] 3GPP standards for 4G systems include an Evolved Packet Core (EPC) and an Enhanced-UTRAN (E-UTRAN: an Enhanced Universal Terrestrial Radio Access Network). The E-UTRAN uses Long Term Evolution (LTE) radio technology. LTE is commonly used to refer to the whole system including both the EPC and the E-UTRAN, and LTE is used in this sense in the remainder of this document. LTE should also be taken to include LTE enhancements such as LTE Advanced and LTE Pro, which offer enhanced data rates compared to LTE.

[0005] In 5G systems a new air interface has been developed, which may be referred to as 5G New Radio (5G NR) or simply NR. NR is designed to support the wide variety of services and use case scenarios envisaged for 5G networks, though builds upon established LTE technologies B5G systems, such as 6G, are currently being considered and developed, and are expected to at least partly build on 5G systems.

[0006] New frameworks and architectures are being developed as part of 5G network (and beyond, such as 6G networks) in order to increase the range of functionality and use cases available through 5G networks.

[0007] One area currently underdevelopment in 3GPP 5G wireless technology is air-to-ground networks (abbreviated ATG or A2G). An Air-To-Ground (abbreviated as ATG or A2G) network is a cellular network that provides connectivity in the air via base stations on the ground. An example of an ATG network is shown in Figure 1. An ATG network is different from a Non-Terrestrial Network (NTN) as the access link is from the ground to the UE in the sky, where as in NTN the access link is from space / sky to the ground. An example of an NTN is shown in Figure 2.

[0008] Referring to FIG. 1, the ATG network is shown to comprise ATG cell 110 and ATG cell 120. ATG cell 110 is associated with (e.g. controlled or configured by) eNB / gNB 130 (i.e. this entity may be an eNB ora gNB). ATG cell 120 is associated with eNB / gNB 140. eNB / gNB 130 and eNB / gNB 140 are connected to core network 150. A UE 160 is shown within ATG cell 120. The UE 160 is connected to eNB / gNB 140 via access link 170; e.g. the UE 160 is communicable connected to the core network 150 via eNB / gNB 140.

[0009] Referring to FIG. 2, the NTN is shown to comprise NTN cell 210 and a NTN entity 280 associated with (e.g. controlling or configuring) NTN cell 210. The NTN entity 280 is connected to a gateway 220 via feeder link 270. The gateway 220 is connected to eNB / gNB 230, which communicates with core network 240. It will be appreciated that gateway 22- and eNB / gNB 230 may be co-located or implemented together. A UE 250 is located with NTN cell 210. The UE 250 is connected to NTN entity 280 via access link 260. Accordingly, the UE 250 is connected to core network 240 via the NTN entity 280.

[0010] One of the main the use cases of ATG / A2G network is to provide backhaul connectivity to access points in aircraft, such as passenger airplanes.

[0011] A Study item was started in Rel-18 (RP-221369 [2]) in RAN4 to define requirements for coexistence between ATG and IMT (International Mobile Telecommunications) terrestrial networks. Furthermore to define RRM (Radio Resource Management) performance requirements for ATG UE, demodulation performance requirements for ATG BS / UE, and test procedures for ATG BS conformance testing.

[0012] The ATG network is similar to a NTN in the sense that the cells can be very large, synchronization will have to be different and that there are network elements that may move very quickly.

[0013] Some of the characteristics from an RF point of view of an ATG network are spelled out in RP-221369 [2]: 1. Extremely large inter-site distances and large coverage range 2. Utilizing non-disjoint frequency for deploying both ATG and terrestrial networks 3. Much more powerful on-board ATG terminal capacity

[0014] Air To Ground System Information

[0015] In the Air-to-Ground work item the following a new System information Block (SIB) was introduced (from TS 38.331 [1]): SIB22 SIB22 contains ATG assistant information. SIB22 information element ATG-Cc-nfig-rlB Gitg-l'feighCellConfigList-rl8 lat eHoni'ritic slEizt^n^icn I AighCGAlCcnfig—r18 ATG-LAighCAllConfig-rlH c arri e r Fr e q-r18 phy<'-'ellI':ArlK AFFClI-\Alu~lIR PhysCAllId SIB22 field descriptions atg-Config Provides parameters needed for the UE to access ATG via NTN access such as atg gNB location information, cell Specific Koffset, TA Report indication. atg-NeighCei / ConfigUst Provides a list of ATG neighbour cells including their reference Location, carrier frequency and PhysCellld. hs-ATG-ceiFRe Indicates whether the UE applies high speed inter-frequency measurements requirements for inter-frequency cell reselection in RRC_IDLE and RRC_INACTIVE states as specified in TS 38.133

[14] , If the field is absent UE applies only the NR cell reselection requirements as specified in TS 38.133 [14[ - ATG-Config The IE ATG-Config provides parameters needed for the UE to access NR via ATG access. ATG-Config information element ATG-r'.jnfi^-rlE :: = h-iqhtql IB~rl6 F eter^n reLc Celt i nn TUB.TF (-16384.. :KellS«aninSK»ff»W^^ .................................................................... T8SOSWe?awfi§isisisisisisi3siUssi^^ ; ATG-Con^ descript ions ( atg-gNB-Location i Indicates the BS location for ATG access. i ceUSpecificKoffsei ; Scheduling offset used for the timing relationships that are modified for ATG.Unit in slot._________________________ i heighigNB ; Indicates the height of the BS for ATG access. Unit in meter._____________________________________________________ i ta-ReportATG i When this field is included in SIB22, it indicates reporting of timing advanced is enabled during Random Access i due to RRC connection establishment or RRC connection resume, and during RRC connection reestablishment. ; When this field is included in ServingCellConfigCommon within dedicated signalling, it indicates TA reporting is i enabled during Random Access due to reconfiguration with sync (see TS 38.321 [3], clause 5.4.8)._____________

[0016] With further information provided in TS 38.331 [1] as follows: The following fields are configurable in an ATG network in SIB22 (and ATG-config): - ATG-Config o atg-gNB-Location and heightgNB. These together form the location of the ATG gNB, which is used for the UE to synchronize, i.e to perform self-precompensation of the Timing Advance. o cellSpecificKoffset. ... o ta-reportATG. Indicates whether a TAR MAC CE shall be triggered upon RRC Setup, RRC Resume, RRC Re-establishment, etc. - ATG-NeighCellConfig. This gives the neighbouring ATG gNB locations

[0017] Non-Terrestrial Network

[0018] NR NTN (NR_NTN_solutions-Core) (RP-211557 [3]) was a 3GPP Work Item in 3GPP Release 17 to define solutions to enable New Radio (NR) and NG-RAN support Non-Terrestrial Networks. It addressed solutions for Transparent payload for both Geostationary and non-Geostationary network scenarios, with the UE having GNSS capability and the satellite beams being both earth-fixed or earthmoving.

[0019] loT (Internet of Things) NTN was a 3GPP study and work item in 3GPP release 17 to provide Non-Terrestrial Network access for E-UTRAN loT devices (NB-loT (narrowband loT) and LTE-M / eMTC) (RP-202689 [4]).

[0020] NR NTN was a work item in Rel-17 to specify adaptation to allow NR to function over NTN (RP-211557 [3]). NTN access may be through Lower Earth Orbit (LEO), Medium Earth Orbit (MEO) and / or Geostationary Orbit (GEO), as well as through High-Altitude Platform Systems (HAPS).

[0021] Following the Work items in Release 17 there were work items to enhance NR NTN (RP-220953 [5]) and loT NTN (RP-220979 [6]) in Release 18.

[0022] NR NTN enhancements (RP-222654 [7]) is a 3GPP Work Item in 3GPP Release 18 that continued to enhance NR NTN with coverage enhancements, NR NTN deployments above 10 GHz, Network-verified UE location and some mobility enhancements.

[0023] Carrier Aggregation and Dual Connectivity

[0024] Carrier Aggregation (CA) is technigue for modern cellular connectivity that was introduced for LTE in Rel-10. It was made native with the first 5G NR release and is an important technigue to ensure higher rates.

[0025] CA, as the name implies, allows for the aggregation of multiple carriers for a single gNB (oreNB, which hereafter will be understood to also be included as another option when reference is made to a gNB in similar context). In addition to the main cell where the UE is RRC-connected to, i.e. the PCell or PSCell, the gNB also configures secondary cells (SCells). Each carrier is some times referred to as a Component Carrier (CC).

[0026] Dual Connectivity (DC) is a technigue that was introduced for LTE in Rel-12 and made native to 5G NR, having some different flavours / types, such as E-UTRAN-NR DC, NR-E-UTRAN DC and NR DC. Dual connectivity allows a UE to simultaneously connect to a Main Node (MR) and Secondary Node (SN), i.e. two different gNBs (or eNB, which hereafter will be understood to also be included as another option when reference is made to a gNB in similar context; or a mix of eNB and gNB).

[0027] In NR, the MN will have an associated Master Cell Group (MCG) and the SN will have an associated Secondary Cell Group (SCG), allowing for Dual Connectivity and Carrier Aggregation to co-exist. A cell group refers to either an MCG or an SCG. The Primary Cell (PCell) refers to the non-secondary cell of the MCG, and the Primary SCG Cell (PSCell) refers to the non-secondary cell of the SCG. Special Cell (SpCell) refers to either the PCell or the PSCell. These gNBs (or eNBs) may or may not be collocated and each node may have multiple SCells, i.e. carriers. In 5G NR a common use case is that the MN / MCG is at FR1 (frequency range 1) and SN / SCG is at FR2 (frequency range 2).

[0028] Compared to CA, in DC the MN and SN will act a lot more independently whereby the MN and SN can configure the UE for instance with separate measurements at each Cell Group.

[0029] SCell Addition

[0030] SCell addition, or CA establishment, is the procedure to add a secondary cell. It is done using carrier aggregation. An example of this procedure can be seen as in Figure 3.

[0031] Figure 3 is a call flow diagram illustrating a method performed by a UE and a gNB comprising (e.g. controlling) a PCell and an SCell.

[0032] In general, the steps of Figure 3 may be described as follows: • S310 - SCell establishment decision. • S320 - RRCReconfiguration. • S330 - RRCReconfiguration-Complete. • S340 - UE configures SCell. • S350 - PDCCH-order Random access. • S360 - Random access to SCell.

[0033] In more detail, the method of FIG. 3 is as follows:

[0034] In operation S310, the network (e.g. gNB or CN) decides that an SCell shall be established. This can for instance be based on determining that service requirements require another SCell, for instance if the throughput is too low. Preceding this may, for instance, be measurements of different carriers to ensure that the signal strength and signal quality is good enough.

[0035] In operation S320, the network configures the UE to add an SCell via RRCReconfiguration. This is configured via sCellToAddModList in the CellGroupConfig. Upon receiving the RRCReconfiguration, the UE configures the SCelI. At this point the SCell cannot be used for transmission, since it is not full synchronized.

[0036] In operation S330, the UE replies with an RRCReconfigurationComplete.

[0037] In operation S340, the UE configures the SCell (e.g. configures use of SCell at UE).

[0038] In operations S350 and S360, in order to get the SCell synchronized, the network triggers a random access procedure using the PDCCH-order. This causes the UE to perform a random access procedure at which the UE will receive a random access response (RAR) with a timing advance (TA), thus synchronizing the UE to the SCell.

[0039] NR DC SCG Addition

[0040] SCG addition (also known as SN addition, SCG establishment, or DC establishment) is a procedure to establish DC by adding another SCG. An example of a procedure to add the SCG from the perspective of the UE can be seen in Figure 4.

[0041] Figure 4 is a call flow diagram illustrating a method performed by a UE, a MN (i.e. a gNB) and a SN (i.e. another gNB).

[0042] In general, the steps of Figure 4 may be described as follows • S410 - SCG establishment decision. • S420 - SN Addition Request I SN Addition Request Acknowledgement. • S430 - RRCReconfiguration. • S440 - RRCReconfiguration-Complete. • S450 - Random Access to SgNB (secondary gNB, i.e. gNB associated with SN or SCG).

[0043] In more detail, the method of FIG. 4 is as follows:

[0044] In operation S410, the decision to attempt to establish an SCG is made.

[0045] In operation S420, the MN initiates the SCG addition by sending an S-Node Addition Request to the SN. If the SN is able to accommodate the UE and the SCG role, the SN generates the SCG RRC configuration and replies with S-Node Addition Request Acknowledge, containing RRC configuration of the SCG that the UE shall apply.

[0046] In operation S430, RRCReconfiguration is sent to the UE to configure the SCG. For example, for NR SCG addition, the mrdc-SecondaryCellGroupConfig is set to nr-SCG and the gNB includes the field CellGroupConfig.

[0047] In operation S440, the UE sends RRCReconfigurationComplete to the MN. RRCReconfigurationComplete may be generated before or after having performed the random access to SN (i.e. performed operation S450). Before, during or after sending RRCReconfigurationComplete, the UE may configure the SCG.

[0048] In operation S450, random access to the SgNB is performed by the UE.

[0049] The RRC message SCGFailurelnformation may be used in order to indicate to a MN that the UE has experienced a failure on the SCG link. This can, for instance, be due to radio link failure, failure to synchronize on the SCG or SCG configuration failure. The SCGFailurelnformation contains a field FailureReportSCG, which may contain the failure type, possible UE measurements, location info, previously visited cells etc.

[0050] EN-DC SCG Addition

[0051] An example of a procedure to add the NR SCG from E-UTRAN MN from the perspective of the UE can be seen in Figure 5.

[0052] Figure 5 is a call flow diagram illustrating a method performed by a UE, a MN (i.e. a eNB) and a SN (i.e. a en-gNB).

[0053] In general, the steps of Figure 5 may be described as follows • S510 - SCG establishment decision. • S520 - SGNB Addition Request I SGNB Addition Request Response. • S530 - RRCConnection-Reconfiguration. • S540 - RRCConnectionReconfiguration-Complete. • S550 - Random access to SgNB.

[0054] In more detail, the method of FIG. 5 is as follows:

[0055] In operation S510, the decision to attempt to establish an SCG is made.

[0056] In operation S520, the MN initiates the SCG addition by sending the SGNB Addition Request to the SN. If the SN is able to accommodate the UE and the SCG role, the SN generates the SCG RRC configuration and replies with SGNB Addition Request Acknowledge, containing RRC configuration of the SCG that the UE shall apply.

[0057] In operation S530, RRCConnectionReconfiguration is sent to the UE to configure the SCG. For example, for NR SCG addition, the nr-SecondaryCellGroupConfig is included as a transparent NR RRC container in the RRCConnectionReconfiguration message, and nr-SecondaryCellGroupConfig contains the configuration to use in the NR SCG.

[0058] In operation S540, the UE sends RRCReconfigurationComplete to the MN. RRCReconfigurationComplete may be generated before or after having performed the random access to SN (i.e. performed operation S550).

[0059] In operation S550, random access to the SgNB is performed.

[0060] Timing Advance Reporting

[0061] In NR Release 15 and in LTE, the timing advance (TA) is signalled in a Timing Advance Command (TAC) by the network. Once received the UE applies the TA, thus the timing is fully controlled by the network.

[0062] Timing Advance reporting is a feature introduced for NR NTN in Release 17. This is introduced because in NR NTN, the UE largely performs self-precompensation of the Timing Advance. In other words the UE autonomously estimates and applies the timing advance. Thus for the network to know what timing advance the UE applies, the UE can be configured to report its timing advance, under certain conditions. These conditions are: — Upon indication from upper layers to trigger the report. This can be after a set of RRC procedures such as RRC setup, Handover (RRC Reconfiguration with Sync), RRC Re-establishment, RRC Connection resume. — If the variation between the current Timing Advance value and the last reported TA is larger than a configured threshold (offsetThresholdTA). It is also triggered when offsetThresholdTA is configured and a Timing Advance Report has not been sent.

[0063] The TA is reported via the Timing Advance Report MAC (medium access control) CE (control element), an example of which can be seen in Figure 6.

[0064] Figure 6 illustrates an example of Timing Advance Report MAC CE 600.

[0065] In 3GPP release 18, for ATG it was also agreed that the Timing Advance MAC CE is supported.

[0066] Koffset

[0067] Another important part of timing is the Koffset, which is a scheduling offset. The Koffset consists for a cell specific part that is signalled in the NTN SIB19, in the field cellSpecificKoffset in the information element NTN-Config. The unit of the Koffset is in the number of slots. The Koffset is calculated as Koffset_cellspecific -Koffset_UE-specific.

[0068] This was also agreed to be applicable for ATG in Release 18.

[0069] In the Release 18 work item Air-To-Ground, several enhancements were introduced, main concepts introduced from the work on NR NTN: — SIB22 which signals information crucial for cell access to an ATG cell: o ATG gNB location consisting of ATG BS reference location and ATG BS height. This is needed for the ATG UE to calculate the propagation delay to the ATG BS and self-precompensate for timing advance and doppler frequency offset o Neighbour cell ATG gNB location, to synchronize and self-precompensate when measuring neighbouring cells — TA report o ATG UE can trigger and report the Timing Advance Report — Barring o A bit that indicates whether an ATG UE is barred or not.

[0070] In Release 19, the main enhancement that will be introduced is Carrier Aggregation (RP-240839, New WID on Enhancements for Air-to-Ground network for NR [8]): — Specify the RF and RRM core requirements for intra-band co-located and inter-band co-located DL CA [RAN4]: o FR1 intra-band contiguous CA ■ Example band combination: n79 o FR1+FR1 inter-band CA ■ Example band combination: n3+n39 — Specify the RF requirements for support of UL MIMO with 2TX for single CC for UE. [RAN4] — Specify signaling and UE capabilities if necessary [RAN2],

[0071] A purpose is of this is improve the maximum throughput, which is important as one of the main use cases ofATG is to provide backhauling for passenger aircraft. The small amount of frequency and bandwidth available for ATG also suggests, if not necessitates, that all available bands shall be aggregated.

[0072] However, CA for ATG has yet to be discussed and several important signaling and synchronization issues will be new compared to terrestrial networks. This is because all of the discussions have assumed only a single carrier, both in NTN and in ATG networks. For instance, such issues include how does a UE self-precompensate on two different links, and what signaling is needed to support this? Issues also remain to be discussed for DC in both NTN and ATG networks. SUMMARY

[0073] It is an aim of certain examples of the present disclosure to address, solve and / or mitigate, at least partly, at least one of the problems and / or disadvantages associated with the related art, for example at least one of the problems and / or disadvantages described herein. It is an aim of certain examples of the present disclosure to provide at least one advantage over the related art, for example at least one of the advantages described herein.

[0074] According to a first aspect of the present disclosure, there is provided a user equipment (UE) comprising: a transmitter; a receiver; and at least one processor configured to: receive, from a first network entity associated with at least one first cell, configuration information for establishing dual connectivity (DC) or carrier aggregation (CA), the configuration information including information on at least one second cell; and establish the at least one second cell as at least one secondary cell (SCell) for CA or a secondary cell group (SCG) for DC, based on the configuration information; wherein establishing the at least one second cell comprises: applying a synchronization associated with the at least one first cell to the at least one second cell, or applying a synchronization based on first synchronization information included in the configuration information to the at least one second cell.

[0075] According to various examples, the synchronization associated with the at least one first cell is for self-precompensation for propagation delay in the at least one first cell.

[0076] According to various examples, the first synchronization information is not included in the configuration information when the synchronization associated with the at least one first cell is applied to the at least one second cell.

[0077] According to various examples, the synchronization associated with the first cell is based on second synchronization information received, from the first network entity, prior to receiving the configuration information.

[0078] According to various examples, the at least one second cell is in the same timing advance group as the at least one first cell when the synchronization associated with the at least one first cell is applied to the at least one second cell.

[0079] According to various examples, the synchronization associated with the at least one first cell is different to a synchronization associated with the at least one second cell when the synchronization based on the first synchronization information is applied to the at least one second cell.

[0080] According to various examples, the at least one processor is configured to: self-precompensate for propagation delay in the established at least one SCell or the SCG; and apply the self-compensation in the at least one first cell.

[0081] According to various examples, the at least one processor is further configured to: perform timing advance reporting based on establishing the at least one SCell or the SCG or based on receiving the configuration information.

[0082] According to various examples, one or more of: the timing advance reporting is performed after establishing the at least one SCell or the SCG; the timing advance reporting is performed in case a physical downlink control channel (PDCCH) ordered random access (RA) is triggered on the at least one SCell; the timing advance reporting is performed based on the configuration information including secondaryCellGroup or an indication to establish DC; the configuration information is included in a RRCReconfiguration message; performing the timing advance reporting comprises including a timing advance report in a message transmitted in the at least one SCell or the SCG following establishment of the of the at least one SCell or the SCG; and the message transmitted in the at least one SCell or the SCG is Msg3.

[0083] According to various examples, one of: the UE is configured to perform the timing advance reporting based on establishing the at least one SCell or the SCG or based on receiving the configuration information as a default operation of the UE; or the configuration information includes a field to configure the UE to perform the timing advance reporting based on establishing the at least one SCell or the SCG or based on receiving the configuration information as a default operation of the UE.

[0084] According to various examples, the at least one processor is configured to: trigger timing advance reporting when there is mobility of the SCG.

[0085] According to various examples, the at least one first cell is a primary cell; and wherein one or more of: the primary cell and the at least one SCell are in the same frequency range; the primary cell and the at least one SCell have the same subcarrier spacing (SCS); and the primary cell and the at least one SCell are contiguous.

[0086] According to various examples, the at least one first cell is included in a master cell group (MCG); and wherein one or more of: the MCG and the SCG are in the same frequency range, ora primary cell (PCell) of the MCG and a primary SCG cell (PSCell) of the SCG are in the same frequency range; the MCG and the SCG have the same subcarrier spacing (SCS), or the PCell and the PSCell have the same SCS; and the MCG and the SCG are co-located, or the PCell and the PSCell are co-located.

[0087] According to various examples, the first synchronization information is included in air-to-ground (ATG) information, non-terrestrial network (NTN) information, SIB19 or SIB22 included in the configuration information; and the configuration information further includes information to add the at least one second cell as the at least one SCell for CA or as the SCG for DC.

[0088] According to a second aspect of the present disclosure, there is provided a network entity associated with at least one first cell, the network entity configured to: determine to establish at least one second cell as at least one secondary cell (SCell) for carrier aggregation (CA) or a secondary cell group (SCG) for dual connectivity (DC) for a user equipment (UE); and transmit, on the at least one first cell, configuration information for establishing CA or DC to the UE; wherein, based on determining a difference in synchronization between the at least one first cell and the at least one second cell, the network entity is configured to include, in the configuration information, first synchronization information for a synchronization applicable for the at least one second cell.

[0089] According to various examples, the network entity is configured to: prior to determining to establish the at least one second cell as at least one SCell or a SCG, transmitting, on the at least one first cell, second synchronization information for a synchronization applicable in the at least one first cell to the UE.

[0090] According to various examples, the at least one second cell is in a different timing advance group to the at least one first cell.

[0091] According to various examples, the network entity is configured to: receive a timing advance report from the UE based on the configuration information being transmitted or the at least one SCell or the SCG being established.

[0092] According to various examples, one or more of: the timing advance report is received after the at least one SCell or the SCG is established; the timing advance report is received after transmitting, to the UE, a physical downlink control channel (PDDCH) order to trigger random access (RA); the configuration information comprises secondaryCellGroup or an indication to establish DC; and the configuration information comprises a field to configure the UE to perform the timing advance reporting based on establishing the at least one SCell or the SCG or based on receiving the configuration information as a default operation of the UE.

[0093] According to various examples, the timing advance report is received in a message received in the at least one SCell or the SCG after the at least one SCell or the SCG is established.

[0094] According to various examples, the at least one first cell is a primary cell; and wherein one or more of: the primary cell and the at least one SCell are in the same frequency range; the primary cell and the at least one SCell have the same subcarrier spacing (SCS); and the primary cell and the at least one SCell are contiguous.

[0095] According to various examples, the at least one first cell is included in a master cell group (MCG); and wherein one or more of: the MCG and the SCG are in the same frequency range, ora primary cell (PCell) of the MCG and a primary SCG cell (PSCell) of the SCG are in the same frequency range; the MCG and the SCG have the same subcarrier spacing (SCS), or the PCell and the PSCell have the same SCS; and the MCG and the SCG are co-located, or the PCell and the PSCell are co-located.

[0096] According to various examples, the first synchronization information is included in air-to-ground (ATG) information, non-terrestrial network (NTN) information, SIB19 orSIB22 included in the configuration information; and / or the configuration information further includes information to add the at least one second cell as the at least one SCell for CA or as the SCG for DC.

[0097] According to a third aspect of the present disclosure, there is provided a method of a user equipment (UE), the method comprising: receiving, from a first network entity associated with at least one first cell, configuration information for establishing dual connectivity (DC) or carrier aggregation (CA), the configuration information including information on at least one second cell; and establishing the at least one second cell as at least one secondary cell (SCell) for CA or a secondary cell group (SCG) for DC, based on the configuration information; wherein establishing the at least one second cell comprises: applying a synchronization associated with the at least one first cell to the at least one second cell, or applying a synchronization based on first synchronization information included in the configuration information to the at least one second cell.

[0098] According to various examples, the method of the UE includes features and / or operations corresponding to any of those described in the examples above relating to the first aspect.

[0099] According to a fourth aspect of the present disclosure, there is provided a method of a network entity associated with at least one first cell, the method comprising: determining to establish at least one second cell as at least one secondary cell (SCell) for carrier aggregation (CA) or a secondary cell group (SCG) for dual connectivity (DC) for a user equipment (UE); and transmitting, on the at least one first cell, configuration information for establishing CA or DC to the UE; wherein, based on determining a difference in synchronization between the at least one first cell and the at least one second cell, the method comprises including, in the configuration information, first synchronization information for a synchronization applicable for the at least one second cell.

[00100] According to various examples, the method of the network entity includes features and / or operations corresponding to any of those described in the examples above relating to the second aspect.

[00101] According to a fifth aspect of the present disclosure, there is provided a computer-readable storage medium comprising instructions which, when executed by at least one processor of an electronic device (e.g. a UE or network entity), causes the electronic device to perform a method according to any aspect or example described above.

[00102] Other aspects, advantages, and salient features of the disclosure will become apparent to those skilled in the art from the following detailed description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[00103] Embodiments / examples of the present disclosure are further described hereinafter with reference to the accompanying drawings, in which: Figure 1 shows a schematic representation of an example of an ATG network. Figure 2 shows a schematic representation of an example of a NTN. Figure 3 is a call flow diagram illustrating a method of adding or establishing a SCell according to various examples. Figure 4 is a call flow diagram illustrating a method of adding or establishing a SCG according to various examples. Figure 5 is a call flow diagram illustrating a method of adding or establishing a NR SCG according to various examples. Figure 6 shows a schematic representation of a Timing Advance Report MAC CE according to various examples. Figures 7a and 7b are call flow diagrams illustrating different methods for adding or establishing a SCell according to various examples. Figures 8a and 8b are call flow diagrams illustrating different methods for adding or establishing a SCG according to various examples. Figure 9 shows a schematic representation of an enhanced Timing Advance Report MAC CE according to various examples.. Figure 10 is a call flow diagram illustrating a method for sending a Timing Advance Report MAC CE, according to various examples. Figures 11a and 11b are call flow diagrams illustrating different methods for sending a Timing Advance Report MAC CE, according to various examples. Figure 12 shows a schematic representation of a differential Koffset MAC CE according to various examples. Figure 13 is a block diagram illustrating an example structure of an entity in accordance with certain examples of the present disclosure. Figure 14 is a flow diagram illustrating a method according to various examples of the present disclosure. Figure 15 is a flow diagram illustrating a method according to various examples of the present disclosure. DETAILED DESCRIPTION

[00104] The following description of examples of the present disclosure, with reference to the accompanying drawings, is provided to assist in a comprehensive understanding of certain examples of the present disclosure. The description includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the examples described herein can be made without departing from the scope of the invention or disclosure.

[00105] The same or similar components may be designated by the same or similar reference numerals, although they may be illustrated in different drawings.

[00106] Detailed descriptions of techniques, structures, constructions, functions or processes known in the art may be omitted for clarity and conciseness, and to avoid obscuring the subject matter of the present disclosure.

[00107] The terms and words used herein are not limited to the bibliographical or standard meanings, but are merely used to enable a clear and consistent understanding of the disclosure.

[00108] Throughout the description of this specification, the words “comprise”, “include” and “contain” and variations of the words, for example “comprising” and “comprises”, means “including but not limited to”, and is not intended to (and does not) exclude other features, elements, components, integers, steps, processes, operations, functions, characteristics, properties and / or groups thereof.

[00109] Throughout the description of this specification, the singular form, for example “a”, “an” and “the”, encompasses the plural unless the context otherwise requires. For example, reference to “an object” includes reference to one or more of such objects.

[00110] Throughout the description, the expression “at least one of A, B and / or C” (or the like), the expression “and / or”, and the expression “one or more of A, B and / or C” (or the like) should be seen to separately include all possible combinations, for example: A, B, C, A and B, A and C, A and B and C.

[00111] Throughout the description of this specification, language in the general form of “X for Y” (where Y is some action, process, operation, function, activity or step and X is some means for carrying out that action, process, operation, function, activity or step) encompasses means X adapted, configured or arranged specifically, but not necessarily exclusively, to do Y.

[00112] Features, elements, components, integers, steps, processes, operations, functions, characteristics, properties and / or groups thereof described or disclosed in conjunction with a particular aspect, embodiment or example are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith.

[00113] Certain examples of the present disclosure relate to methods, apparatus and / or systems for establishing or configuring carrier aggregation and / or dual connectivity in a network. In particular, in various examples the network is a Air-to-Ground network or a Non-Terrestrial Network. In various examples, SCell addition for a UE in the network is described. In various examples, SCG addition for a UE in the network is described. Other examples include methods and / or apparatus in which a UE transmits timing advance information in the network, where carrier aggregation and / or dual connectivity is configured for the UE. Various examples disclose a timing advance report MAC CE transmitted by the UE. In various examples, there is provided a Koffset MAC CE.

[00114] The following examples are applicable to, and use terminology associated with, 3GPP 5G. However, the skilled person will appreciate that the techniques disclosed herein are not limited to these examples or to 3GPP 5G, and may be applied in any suitable system or standard, for example one or more existing and / or future generation wireless communication systems or standards. The skilled person will appreciate that the techniques disclosed herein may be applied in any existing or future releases of 3GPP 5G NR or any other relevant standard. For example, the functionality of the various network entities and other features disclosed herein may be applied to corresponding or equivalent entities or features in other communication systems or standards. Corresponding or equivalent entities or features may be regarded as entities or features that perform the same or similar role, function, operation or purpose within the network. In particular, the following disclosure should be considered at least in relation to 6G also, which is expected to use at least part of the 5G architecture, or equivalent, and to which the present disclosure also relates.

[00115] A particular network entity may be implemented as a network element on a dedicated hardware, as a software instance running on a dedicated hardware, and / or as a virtualised function instantiated on an appropriate platform, e.g. on a cloud infrastructure.

[00116] The skilled person will appreciate that the present disclosure is not limited to the specific examples disclosed herein. For example: • The techniques disclosed herein are not limited to 3GPP 5G, B5G or 6G. • One or more entities in the examples disclosed herein may be replaced with one or more alternative entities performing equivalent or corresponding functions, processes or operations. • One or more of the messages in the examples disclosed herein may be replaced with one or more alternative messages, signals or other type of information carriers that communicate equivalent or corresponding information. • One or more further elements, entities and / or messages may be added to the examples disclosed herein. • One or more non-essential elements, entities and / or messages may be omitted in certain examples. • The functions, processes or operations of a particular entity in one example may be divided between two or more separate entities in an alternative example. • The functions, processes or operations of two or more separate entities in one example may be performed by a single entity in an alternative example. • Information carried by a particular message in one example may be carried by two or more separate messages in an alternative example. • Information carried by two or more separate messages in one example may be carried by a single message in an alternative example. • The order in which operations are performed may be modified, if possible, in alternative examples. • The transmission of information between network entities is not limited to the specific form, type and / or order of messages described in relation to the examples disclosed herein.

[00117] Certain examples of the present disclosure may be provided in the form of an apparatus / device / network entity configured to perform one or more defined network functions and / or a method therefor. Such an apparatus / device / network entity may comprise one or more elements, for example one or more of receivers, transmitters, transceivers, processors, controllers, modules, units, and the like, each element configured to perform one or more corresponding processes, operations and / or method steps for implementing the techniques described herein. For example, an operation / function of X may be performed by a module configured to perform X (or an X-module). Certain examples of the present disclosure may be provided in the form of a system (e.g., a network) comprising one or more such apparatuses / devices / network entities, and / or a method therefor.

[00118] It will be appreciated that examples of the present disclosure may be realized in the form of hardware, software or a combination of hardware and software. Certain examples of the present disclosure may provide a computer program comprising instructions or code which, when executed, implement a method, system and / or apparatus in accordance with any aspect, example and / or embodiment disclosed herein. Certain embodiments of the present disclosure provide a machine-readable storage storing such a program.

[00119] A network according to one or more of the examples disclosed herein may include one or more of a Network Data Analytics Function (NWDAF) entity, an Access and Mobility Management Function (AMF) entity, a Session Management Function (SMF) entity, a Network Slice Selection Function (NSSF) entity, a Network Repository Function (NRF) entity, Application Function (AF) entity, and an Operation and Maintenance (OAM) entity. The network may include one or more Service Consumers (including one or more of the entities mentioned above and / or one or more other entities) that receive analytics from NWDAF. The skilled person will appreciate that a network may omit one or more of the entities mentioned above and / or may comprise one or more additional entities

[00120] As described above, there are issues relating to CA and DC in ATG networks and NTNs which have yet to be discussed and at present do not have solutions. Also, the timing advance report is important to ensure that the network is made aware of the timing advance to the gNB. So far, the timing advance report has only been considered in a single cell scenario. Various examples, embodiments, aspects etc. of the present disclosure aim to aim to address one or more of these issues.

[00121] According to an aspect of the present disclosure, there are provided methods for configuring CA and / or DC in an ATG scenario, in particular focusing on how synchronization information and configurations are handled.

[00122] While the examples disclosed herein are mostly described in terms of NR ATG, it will be appreciated that some of the features may also apply to establishing and operating CA and / or DC in NR NTN, as well as E-UTRA NTN, or even E-UTRA ATG. Especially in the case of NR NTN, since CA and DC have yet to be introduced. For instance, “ATG-Config” can be replaced by “NTN-Config”, SIB22 can be replaced by SIB19 etc. In other words, the examples disclosed herein should not be seen to be limited to NR ATG - this is simply for illustrative purposes. The examples (or analogous examples) can be applied to NR NTN, E-UTRA NTN and / or E-UTRA ATG also, for example with appropriate modification such as replacing “ATG-Config” with “NTN-Config” and replacing SIB22 with SIB19 as would be understood by the skilled person.

[00123] In the below, “ATG information” may be or include information needed for an ATG UE (i.e. a UE capable of operating in an ATG network) to establish ATG connectivity. This can, for example, be synchronization information, which can comprise one or more of the ATG BS location, the Koffset, the Kmac or similar. It will be understood that Kmac is a scheduling offset used if the downlink and uplink frame timing is not aligned at the gNB. Kmac is used to delay the application of a downlink configuration indicated by a MAC CE, when estimating the UE-to-gNB Round trip delay as well during random access procedures For example, the ATG information or synchronization information includes information element ATG-Config. ATG information may more generally be referred to as information, configuration information or the like.

[00124] In the following, particular types of signalling, such as RRC, may be referred to in relation to certain operations. However, it will be understood that the present disclosure envisages examples where signalling in these operations is not limited to the particular type(s) (e.g. RRC), and so supports more general reference to signalling or the transmission / reception of messages.

[00125] Since CA may be employed in DC, the methods below should not be viewed in isolation. That is, a method that is used for DC may be adapted to be used for CA also, and a method that is used for CA may be adapted to be used for DC also.

[00126] When configuring DC, the node configuring the related ATG configuration may either be the MN orSN, or the base station (in case it is implemented as a single node).

[00127] Herein, when referring to PCell, other cells such as Special Cell (SpCell) or Primary SCG cell may also be used (i.e. referring to instead or additionally), as CA can be configured in an SCG. Also, the terms ‘configuring SCG’ or ‘adding SCG’ may also mean that the PSCell is established and does not imply SCG SCell(s) are established. Also, SN may also be referred to as PSCell.

[00128] According to various examples of the present disclosure, the network signals ATG information when adding or establishing a SCell (for CA) or an SCG (for DC). This can mean that ATG-Config is signalled. For example, this means that atg-gNB-Location, heightgNB, cellSpecificKoffset and ta-ReportATG are all applied in SCell or SCG.

[00129] For example, the UE is configured to receive, from the network (e.g. from gNB / eNB (in the case of CA) or from MN (in the case of DC) the ATG information, following the network deciding to add (or establish) a SCell (for CA) or a SCG (for DC).

[00130] In various examples, there are conditions when this is done (i.e. when the network signals the ATG information), such as if there is sufficient difference in how a UE would synchronize to the specific SCell or the PSCell. As an example, one condition is if there is a sufficient difference in frequency, such as the PCell or MCG being FR1 and SCell or PSCell or SCG being in FR2. Other examples of conditions are that the SCS (subcarrier spacing) between PCell or MCG and SCell, PSCell or SCG is different. In other words, in general, it may be required that the ATG information is provided if one or more of the conditions above are fulfilled (or, more generally, upon fulfilment of a condition).

[00131] Figure 7a shows an example of a method in which the network signals ATG information when establishing an SCell. The method of Figure 7a is performed between a UE and a gNB (oreNB) comprising (e.g. controlling) a PCell and an SCell. Various examples of the present disclosure include the operations of each individual entity in isolation.

[00132] In general, the steps of Figure 7a may be described as follows: • S710a - SCell establishment decision. • S720a - RRCReconfiguration configuring SCell(s), including ATG configuration. • S730a - RRCReconfiguration-Complete. • S740a - UE configures SCell using configured ATG configuration. • S750a - PDCCH-order random access. • S760a - Random access to SCell.

[00133] In more detail:

[00134] In operation S710a, the network (e.g. gNB or CN) decides that an SCell shall be established. This can for instance be based on determining that service requirements require another SCell, for instance if the throughput is too low. Preceding this may, for instance, be measurements of different carriers to ensure that the signal strength and signal quality is good enough.

[00135] In operation S720a, the network configures the UE to add an SCell via RRCReconfiguration. Further, the network signals ATG information when adding or establishing a SCell (for CA) or an SCG (for DC). This can mean that ATG-Config is signalled. For example, as part of operation S720a, the UE receives ATG information (or NTN information, for a case of an NTN). This may be received via RRC signalling, such as RRCReconfiguration. For example, this means that atg-gNB-Location, heightgNB, cellSpecificKoffset and ta-ReportATG are all applied in SCell.

[00136] In operation S730a, the UE replies to the gNB (e.g. on PCell) with RRCReconfigurationComplete message.

[00137] In operation S740a, the UE configures the SCell based on the received RRCReconfiguration message. Here, the UE configures the SCell based on (e.g. using) the ATG information.

[00138] The order in which operations S730a and S740a are performed may be varied. For example, operation S730a can be performed before operation S740a, after operation S740a or concurrently (e.g. overlapping with) operation S740a).

[00139] In operations S750a and S760a, in order to get the SCell synchronized, the network triggers a random access procedure using the PDCCH-order. This causes the UE to perform a random access procedure at which the UE will receive a RAR with a TA, thus synchronizing the UE to the SCell.

[00140] It will be appreciated that operations S750a and S760a may be omitted from examples according to FIG. 7a.

[00141] ForCA, the required information (e.g. ATG information, or equivalent NTN information) may be included in sCellToAddModList in the CellGroupConfig, or added in SCellConfig (an example of howto implement this (e.g. changes to be introduced in TS 38.331 [1]) can be seen in Example #1 in the Annex below). Alternatively, it can be a separate list, such as atg-ConfigToAddModList in CellGroupConfig.

[00142] Figure 8a shows an example of a method in which network signals ATG information when establishing an SCG. The method of Figure 8a is performed between a UE, a MN and a SN. Various examples of the present disclosure include the operations of each individual entity in isolation.

[00143] In general, the steps of Figure 8a may be described as follows: • S810a - SCG establishment decision. • S820a - RRCReconfiguration configuring SCG, including ATG configuration. • S830a - RRCReconfiguration-Complete. • S840a - UE configures SCG using configured ATG configuration. • S850a - Random access to SN.

[00144] In more detail:

[00145] In operation S810a, the decision to attempt to establish an SCG is made. For example, MN (e.g. a corresponding gNB or the CN) determines to establish a SCG for the UE.

[00146] In various examples (not illustrated in FIG. 8a), the MN initiates the SCG addition by sending an S-Node Addition Request to the SN. If the SN is able to accommodate the UE and the SCG role, the SN generates the SCG RRC configuration and replies with S-Node Addition Request Acknowledge, containing RRC configuration of the SCG that the UE shall apply. It will be appreciated that these details may be omitted from examples in accordance with Figure 8a.

[00147] In operation S820a, the MN sends RRCReconfiguration to the UE, for adding or establishing SCG. In operation S820a, the MN also transmits ATG information (or NTN information, for the case of a NWN) or information for ATG configuration (e.g. ATG configuration) to the UE. That is, for example, the UE receives RRCReconfiguration message including information for adding the SCG and ATG information.

[00148] In operation S830a, the UE responds with RRCReconfigurationComplete. For example, the UE sends a RRCReconfigurationComplete message to the MN.

[00149] In operation S840a, the UE configures the SCG using the ATG information. Here, the UE may also configure the SCG using other information in the RRCReconfiguration.

[00150] The order in which operations S830a and S840a are performed may be varied. For example, operation S830a can be performed before operation S840a, after operation S840a or concurrently (e.g. overlapping with) operation S840a).

[00151] In operation S850a, random access to the SgNB (i.e. SN gNB) is performed by the UE. It will be appreciated that this operation may be omitted.

[00152] For DC, the required information (e.g. ATG information, or NTN equivalent) can be included in CellGroupConfig, in SpCellConfig, in spCellConfigDedicated or in reconfigurationWithSync.

[00153] The above ATG information for SCell(s) or SCG can be different from the ATG information in the serving cell, i.e. different from ATG information in the PCell (for CA) or the MCG (for DC). For example, it can be different due to the synchronization requirements being more stringent; if this is the case, the ATG synchronization information for SCell(s) or SCG such as the ATG BS location may be more precise.

[00154] In an alternative of the above relating to other examples of the present disclosure, if there is no need to have different synchronization (e.g. in how the UE synchronises to SCell and to PCell, or in how the UE synchronises to MCG or SCG), the network may not signal ATG information when establishing CA or DC.

[00155] In such examples, the UE is configured to apply the PCell synchronization in the SCell(s) or the PCell synchronization in the PSCell or SCG cells. In other words, when the UE self-precompensates for the propagation delay in the PCell, the UE uses the same self-precompensation in the SCell or the PSCell or SCG. An example of this can be seen in Figure 7b.

[00156] Figure 7b shows an example of a method in which the UE uses PCell or existing ATG configuration (e.g. existing ATG information) when configuring SCell. The method of Figure 7b is performed between a UE and a gNB (or eNB) comprising (e.g. controlling) a PCell and an SCell. Various examples of the present disclosure include the operations of each individual entity in isolation.

[00157] In general, the steps of Figure 7b may be described as follows: • S710b - SCell establishment decision. • S720b - RRCReconfiguration configuring SCell(s). • S730b - RRCReconfiguration-Complete. • S740b - UE configures SCell using PCell ATG configuration. • S750b - PDCCH-order random access. • S760b - Random access to SCell.

[00158] In more detail:

[00159] In operation S710b, the network (e.g. gNB or CN) decides that an SCell shall be established. This can for instance be based on determining that service requirements require another SCell, for instance if the throughput is too low. Preceding this may, for instance, be measurements of different carriers to ensure that the signal strength and signal quality is good enough.

[00160] In operation S720b, the network configures the UE to add an SCell via RRCReconfiguration.

[00161] In operation S730b, the UE replies to the gNB (e.g. on PCell) with RRCReconfigurationComplete message.

[00162] In operation S740b, the UE configures the SCell based on the PCell ATG configuration. Here, the UE configures the SCell based on (e.g. using) existing ATG information associated with the PCell, as described above. For example, operation S740b is performed in a case where there is no need to have different synchronization. It will be appreciated that, in various examples of the present disclosure, the UE configures the SCell based on received ATG information (e.g. such as in operation S740a) if ATG information for the SCell is received, and if ATG information for the SCell is not received then configure the SCell based on PCell ATG information as in operation S740b. In other words, various examples of the present disclosure include combinations of the methods of Figures 7a and 7b, such as where a UE configures an SCell (to be added) depending on (e.g. based on) whether ATG information is received with / in the RRCReconfiguration.

[00163] The order in which operations S730b and S740b are performed may be varied. For example, operation S730b can be performed before operation S740b, after operation S740b or concurrently (e.g. overlapping with) operation S740b).

[00164] In operations S750b and S760b, in order to get the SCell synchronized, the network triggers a random access procedure using the PDCCH-order. This causes the UE to perform a random access procedure at which the UE will receive a RAR with a TA, thus synchronizing the UE to the SCell.

[00165] It will be appreciated that operations S750b and S760b may be omitted from examples according to FIG. 7b.

[00166] Figure 8b shows an example of a method in which the UE uses MN or existing ATG configuration when configuring SCG. The method of Figure 8b is performed between a UE, a MN and a SN. Various examples of the present disclosure include the operations of each individual entity in isolation.

[00167] In general, the steps of Figure 8b may be described as follows: • S81 Ob - SCG establishment decision. • S820b - RRCReconfiguration configuring SCG. • S830b - RRCReconfiguration-Complete. • S840b - UE configures SCG using MCG ATG configuration. • S850b - Random access to SN.

[00168] In more detail:

[00169] In operation S810b, the decision to attempt to establish an SCG is made. For example, MN (e.g. a corresponding gNB or the CN) determines to establish a SCG for the UE.

[00170] In various examples (not illustrated in FIG. 8b), the MN initiates the SCG addition by sending an S-Node Addition Request to the SN. If the SN is able to accommodate the UE and the SCG role, the SN generates the SCG RRC configuration and replies with S-Node Addition Request Acknowledge, containing RRC configuration of the SCG that the UE shall apply.

[00171] In operation S820b, the MN sends RRCReconfiguration to the UE, for adding or establishing SCG.

[00172] In operation S830b, the UE responds with RRCReconfigurationComplete. For example, the UE sends a RRCReconfigurationComplete message to the MN.

[00173] In operation S840b, the UE configures the SCG using MCG ATG information. For example, the UE configures the SCG using the existing ATG configuration of the MCG. Here, the UE may also configure the SCG using other information in the RRCReconfiguration. It will be appreciated that, in various examples of the present disclosure, the UE configures the SCG based on received ATG information (e.g. such as in operation S840a) if ATG information for the SCG is received, and if ATG information for the SCG is not received then configure the SCG based on MCG ATG information as in operation S840b. In other words, various examples of the present disclosure include combinations of the methods of Figures 8a and 8b, such as where a UE configures an SCG (to be added) depending on (e.g. based on) whether ATG information is received with / in the RRCReconfiguration.

[00174] The order in which operations S830b and S840b are performed may be varied. For example, operation S830b can be performed before operation S840b, after operation S840b or concurrently (e.g. overlapping with) operation S840b).

[00175] In operation S850b, random access to the SgNB (i.e. SN gNB) is performed by the UE. It will be appreciated that this operation may be omitted.

[00176] In other examples, similar to the above, the UE is configured to self-precompensate in the SCell or PSCell or SCG and to use the same or similar self-precompensation in the PCell. This may be relevant in the case where the SCS or frequency is higher in the SCell or PSCell or SCG (e.g. than the PCell or MCG). This can mean that the Timing Advance is first computed in the SCell or PSCell or SCG and then the same Timing Advance is quantized to the lower SCS in the PCell.

[00177] In both cases (i.e. when PCell ATG information is used in SCell configuration at the UE), the UE uses the information signaled (e.g. via SIB22 and dedicated information) in the PCell to perform self-precompensation both in PCell and SCell(s) or both in PCell and PSCell and / or SCG. The difference between these approaches is that: in the first case, the estimated TA is different in PCell and SCell(s) or PCell and PSCell or SCG; and, in the second case, the estimated TA is exactly the same in the PCell and SCell(s) or PCell and PSCell or SCG. It will be appreciated that the information signaled in the PCell (used by the UE to perform self-precompensation) may be signalled prior to the network deciding to add or establish SCell (i.e. the ATG information for the PCell may have been communicated to the UE earlier).

[00178] In order to establish the CA or DC, in various examples of the present disclosure the network includes the SIB22 for a SCell, a PSCell or for a SCG. For example, the SIB22 includes the ATG information (or, for the case of NTN, consider SIB19 instead of SIB 22). This is because in some cases the UE would not have to acquire system information in the cell when establishing an SCell. In alternative examples, if the SCell or SN SIB22 is exactly the same as the PCell, then the network may not configure the SIB22, and the UE will be configured to apply the same information that the SIB22 signals for the PCell as in the SCell. This may also be a condition for the UE; if SIB22 is provided when establishing CA or DC, the UE performs synchronization according to the provided ATG information, and if the SIB22 is not present, the UE performs synchronization according to MN or PCell SIB22.

[00179] It may be that the methods for CA and DC are applied differently. For instance, in DC, it may be required to configure ATG information when establishing DC (e.g. analogous to the case of operation 840a); whereas establishing CA in a DC setting (e.g. SCells in SCG) may not require ATG information, but instead SCG SCells use the synchronization of the PSCell (e.g. ATG information of the PCell, for example analogous to the case of operation 840b).

[00180] In other examples, in an ATG network (e.g. for the case of ATG in general) it may be required that the SCell or SCG or PSCell have to be in the same Timing Advance Group as the PCell. In further examples, a condition (e.g. in addition to or as an alternative to any condition described above) for the SCell, SCG or PSCell to use the synchronization of the PCell is that the cells are in the same TAG as the PCell.

[00181] In various examples, when establishing an SCell or a SCG or PSCell, the Koffset that is applied is based on the Koffset that is signalled in the PCell SIB19. Alternatively, it can be such that the Koffset that is applied is the same Koffset that is applied in the PCell, which can be the signalled Koffset in SIB19 as well as the dedicatedly configured Koffset signalled via the Differential Koffset MAC CE.

[00182] According to various examples of the present disclosure, the timing advance reporting may be triggered in a CA setting.

[00183] In various examples, the network (e.g. gNB, eNB) configures triggering of TA reporting based on an offset threshold. In other words, the UE can be configured to trigger a Timing Advance Report MAC CE if the variation between the current estimate of the Timing Advance value and the last reported Timing Advance value is equal to or larger than a configure timing advance offset threshold. This may be configured via an offsetThresholdTA for a specific SCell. Alternatively, it may be a threshold configured for all SCells in a cell group offsetThresholdTA-SCell. In a further alternative, the offsetThresholdTA and timingAdvanceSR is applied for all SCells in a cell group.

[00184] In further examples, if TA reporting is configured for an SCell, for instance via TAR-Config, the UE is not configured to trigger the TAR MAC CE upon configuration, as would be done in related art for PCell. This can be useful as it may only be useful to have the TAR MAC CE triggered according to when timing advance changes (i.e. the change of the estimated timing advance is above threshold offsetThresholdTA). Thus when configuring offsetThresholdTA for a cell (PCell or SCell), the TAR MAC CE is triggered for PCell only and not when offsetThresholdTA is configured for an SCell.

[00185] In a further example of triggering the TAR MAC CE, the condition may be that a difference between reported PCell timing advance and estimated SCell timing advance is larger than offsetThresholdTA or offsetThresholdTA-SCell. In other words, the PCell and SCell timing is compared to trigger TAR MAC CE. Comparing PCell and SCell timing advance may be configured by the network in the TAR-Config.

[00186] In some cases, one issue when the TAR MAC CE is triggered is that a single MAC entity is only made to trigger a single TAR MAC CE. Furthermore, the TAR MAC CE is only defined for the 15 kHz SCS, and to only be signalled for a single carrier.

[00187] Accordingly, in various examples of the present disclosure, the TAR MAC CE is only sent on a specific cell, i.e. the PCell or an SCell, according to which cell that triggered the TAR MAC CE. This may mean that it is possible to trigger and queue two different TAR MAC CEs, and that a new (or later) TAR MAC CE shall not cancel the TAR MAC CE (or earlier TAR MAC CE) of another cell. Similarly, in examples where, the reporting is done per serving cell, the last report Timing Advance value is only per cell. Thus the TAR MAC CE reporting procedure are per cell.

[00188] In alternative examples, the TAR MAC CE is sent on any serving cell (PCell or SCell(s)). In a further alternative, the TAR MAC CE can only be sent on PCell, PSCell or SpCell.

[00189] An example of the action of reporting TAR MAC CE during CA operation can be seen in Figure 10. FIG. 10 is a call flow diagram showing a method of triggering sending a timing advance report according to an example of the present disclosure. That is, Figure 10 may be seen to show triggering TAR MAC CE based on SCell, sending TAR MAC CE to PCell or SCell.

[00190] The method of Figure 10 is performed between a UE and a gNB (oreNB) comprising (e.g. controlling) a PCell and an SCell. Various examples of the present disclosure include the operations of each individual entity in isolation.

[00191] In general, the steps of FIG. 10 may be described as follows: • S1010 - Configure Timing Advance Reporting for SCell. . S1020 - SCell triggers TAR MAC CE. • S1030 - Trigger and send TAR MAC CE (to PCell or SCell).

[00192] An example of howto implement (e.g. changes to be introduced in TS 38.331 [1]) reporting TAR MAC CE per serving cell can be seen in Example #4 in the Annex below.

[00193] If an SCell may trigger a TAR MAC CE, but the TAR MAC CE can be sent on a PCell, it may be useful to provide methods to ensure that the network can distinguish different TAR MAC CE. Otherwise the network may not know which cells that triggered the MAC CE. Thus, various examples of the present introduce a SCell TAR MAC CE. The SCell TAR MAC CE may, in addition to the timing advance estimate, also include the SCell index. In various examples, the network (e.g. gNB or CN) determines which cell triggered a TAR MAC CE based on whether the TAR MAC CE includes an SCell index or an indication of an SCell.

[00194] In other examples, a new MAC CE specifically for CA is introduced to signal TAR for any serving cell, including PCell. For instance, this can be called a Enhanced TAR MAC CE, or a Carrier Aggregation TAR MAC CE. This MAC CE would include the cell index in addition to the timing advance estimate. The network would thus know the resolution of the timing advance field since the network would know the SCS of the specific cell. To support larger SCSs compared to 15 kHz, the timing advance field can be increased, as the number of slots are increased with higher SCS, thus requiring a larger Timing Advance field. An example of the Enhanced TAR MAC CE can be seen in Figure 9.

[00195] Figure 9 illustrates an example of enhanced Timing Advance Report (TAR) MAC CE 900. Enhanced TAR MAC CE comprises an increased TA field, and a serving cell ID indicating the serving cell to which the TAR corresponds.

[00196] In other examples, the SCell cannot trigger a Timing Advance report. This means that the triggering is only based on the PCell or SpCell.

[00197] In another example, if the ATG gNB location is the same across the different serving cells, the cell with the larger SCS triggers the TAR MAC CE. This can make sense as the larger the SCS, the more granular and thus the earlier the triggering of the TAR MAC CE. For example, the UE is configured to transmit TAR MAC CE for a cell with largest SCS, based on the ATG gNB location and / or SCS of each cell (e.g. of PCell and SCell(s)).

[00198] Some of the above methods may only be applicable if the cells in a CA scenario have different SCS and or different ATG synchronization. Thus, configuring the above may have the condition that the SCS or the configured ATG gNB location is different. Similarly, in some cases, if there are a set of cells with the same SCS and a set of cells with a different SCS, then the TAR MAC CE reporting may only be different for these two set of cells. For example, within the sets of cells, the TAR MAC CE reporting is the same.

[00199] According to various examples of the present disclosure, the timing advance reporting is performed when the UE performs CA or DC establishment. For example, TA reporting is triggered following CA or DC establishment.

[00200] In some examples, for timing advance reporting in a DC establishment, this is done when the UE receives a secondaryCellGroup in RRCReconfiguration message. The timing advance report MAC CE may be included in the Msg3, in this case. This can be configured to be a default operation when the UE establishes an SCG, or it can be configured via ta-Report in SCG configuration, or using a separate bit ta-ReportSCG. An example of how to implement this (e.g. changes to be introduced in TS 38.331 [1]) can be seen in Example #2 in the Annex below.

[00201] Similarly, according to various examples, when there is mobility of the SCG, the UE is configured to trigger the Timing Advance Report MAC CE.

[00202] In various examples, for timing advance reporting, to trigger the Timing Advance report MAC CE, the UE may be triggered to include the MAC CE if a SCell is established. Alternatively, the UE may be triggered to report (or configured to report) the Timing Advance Report MAC CE if a PDCCH-ordered random access is triggered on the SCell. Both of these actions may be default operation, or may be specifically configured via for instance ta-Report configured on an SCell or a specific bit ta-ReportSCell. Examples of this can be seen in Figures 11a and 11b, relating to CA and DC cases respectively. Also, an example of how to implement this (e.g. changes to be introduced in TS 38.331 [1]) can be seen in Example #3 in the Annex below.

[00203] Figure 11a is a call flow diagram showing a method of sending a timing advance report according to an example. That is, Fig. 11a may be seen to show sending TAR MAC CE during SCell addition.

[00204] The method of Figure 11a is performed between a UE and a gNB (oreNB) comprising (e.g. controlling) a PCell and an SCell. Various examples of the present disclosure include the operations of each individual entity in isolation.

[00205] In general, the steps of FIG. 11a may be described as follows: • S1110a - SCell establishment decision. • S1120a - RRCReconfiguration configuring SCell(s). • S1130a - RRCReconfiguration-Complete. • S1140a - UE configures SCell. • S1150a - PDCCH-order random access. • S1160a - Random access to SCell. • S1170a - Trigger and send TAR MAC CE (to PCell or SCell).

[00206] In an example of the above, referring to operation S1140a, here the UE is configured to send the TA report following establishment of the SCell (e.g. sending the RA report in such a circumstance is set as default behaviour in the UE). This may be an alternative to sending TAR MAC CE in S1170a, or in addition to sending TAR MAC CEinS1170a.

[00207] Figure 11b is a call flow diagram showing a method of sending a timing advance report according to an example. That is, Fig. 11 b may be seen to show sending TAR MAC CE during SCell addition.

[00208] The method of Figure 11b is performed between a UE, a MN and a SN. Various examples of the present disclosure include the operations of each individual entity in isolation.

[00209] In general, the steps of FIG. 11 b may be described as follows: • S1110b — SCG establishment decision. • S1120b - RRCReconfiguration configuring SCG. • S1130b - RRCReconfiguration-Complete. • S1140b - UE configures SCG using MCG ATG configuration. • S1150b - Random access to SN. • S1160b - Trigger and send TAR MAC CE to SN.

[00210] In an example of the above, referring to operation S1140b, here the UE is configured to send the TA report following establishment of the SCG (e.g. sending the RA report in such a circumstance is set as default behaviour in the UE). This may be an alternative to sending TAR MAC CE in S1160b, or in addition to sending TAR MAC CEinS1160b.

[00211] In another example, the TA report is triggered during SCG mobility, i.e. when the MCG remains the same, but the SCG or the SN changes. For example, a UE is configured to transmit a TA report to a new SCG when an SCG is changed to the new SCG from a previously established SCG.

[00212] According to various examples, when establishing carrier aggregation or dual connectivity there may need to be conditions fulfilled.

[00213] Some examples of these conditions forCA are: — PCell and SCell must be in the same frequency range, i.e. in FR1, FR2-1 or FR2-2. — PCell and SCell must have the same SCS. — PCell and SCell must be contiguous.

[00214] Some examples of these conditions for DC are: — MCG or PCell and SCG or PSCell must be in the same frequency range, i.e. in FR1, FR2-1 orFR2-2. — MCG or PCell and SCG or PSCell must have the same SCS. — MCG or PCell and SCG or PSCell must be co-located.

[00215] Various examples of the present disclosure include any combination of the above examples of conditions.

[00216] In various examples, the differential Koffset is signalled using a MAC CE. In various examples, the differential Koffset MAC CE is enhanced to indicate which serving cell that shall have its Koffset changed. Owing to the different SCSs, the Differential Koffset field may be larger. An example of a differential Koffset MAC CE 1200 is shown in Figure 12.

[00217] According to an example of the present disclosure, there is provided a first entity (e.g. a UE) in an ATG network, the first entity configured to: receive, from a second entity (e.g. gNB) in the ATG network, first information for configuring a cell in the ATG network and second information for adding the cell associated with the second entity; and configure the cell based on the first information and the second information. Optionally, the first information and the second information are received via RRC signalling. Optionally, the first information and the second information are included in RRCReconfiguration message. Optionally, the cell is an SCell, and the first information and the second information are received on a PCell associated with the second entity. Optionally, the first information comprises synchronization information for the ATG network, e.g. one or more of ATG BS location, the Koffset, the Kmac or similar.

[00218] According to another example of the present disclosure, there is provided a first entity (e.g. a UE) in an NTN, the first entity configured to: receive, from a second entity (e.g. gNB) in the NTN, first information for configuring a cell in the NTN network and second information for adding the cell associated with the second entity; and configure the cell based on the first information and the second information. Optionally, the first information and the second information are received via RRC signalling. Optionally, the first information and the second information are included in RRCReconfiguration message. Optionally, the cell is an SCell, and the first information and the second information are received on a PCell associated with the second entity. Optionally, the first information comprises synchronization information for the NTN.

[00219] According to an example of the present disclosure, there is provided a first entity (e.g. a UE) in an ATG network, the first entity configured to: receive, from a second entity (e.g. gNB) in the ATG network, first information for configuring a cell group in the ATG network and second information for adding the cell group associated a third entity in the ATG network; and configure the cell group based on the first information and the second information. Optionally, the first information and the second information are received via RRC signalling. Optionally, the first information and the second information are included in RRCReconfiguration message. Optionally, the cell group is an SCG, and the first information and the second information are received from a MCG associated with the second entity. Optionally, the first information comprises synchronization information for the ATG network, e.g. one or more of ATG BS location, the Koffset, the Kmac or similar.

[00220] According to another example of the present disclosure, there is provided a first entity (e.g. a UE) in an NTN, the first entity configured to: receive, from a second entity (e.g. gNB) in the NTN, first information for configuring a cell group in the NTN network and second information for adding the cell group associated with a third entity in the NTN; and configure the cell group based on the first information and the second information. Optionally, the first information and the second information are received via RRC signalling. Optionally, the first information and the second information are included in RRCReconfiguration message. Optionally, the cell group is an SCG, and the first information and the second information are received from a MCG associated with the second entity. Optionally, the first information comprises synchronization information for the NTN.

[00221] According to another example, there is provided a first entity (e.g. a UE) in a ATG network or a non-terrestrial network, the first entity is configured to: receive, from a second entity in the network, configuration information for TA reporting for a cell associated with the second entity; detect a condition for reporting TA for the cell; and transmit TA report to the cell or to another cell associated with the second entity, based on detecting the condition. Optionally, the cell is a SCell and / or the other cell is a PCell. Optionally, the TA report is a TAR MAC CE. Optionally, the condition is based on an offset threshold; for example, the first entity transmits the TA report if the variation between a current estimate of the Timing Advance value and a last reported Timing Advance value is equal to or larger than a configured (e.g. predetermined) timing advance offset threshold. Optionally, the TA report comprises an indication of the cell (e.g. SCell index) and / or an increased TA field (e.g. the increased TA field is provided based on whether SCS larger than 15kHz are supported).

[00222] According to another example, there is provided a first entity (e.g. a UE) in a ATG network or a non-terrestrial network, the first entity is configured to: receive, from a second entity in the network, configuration information for TA reporting for a cell associated with the second entity; detect a condition for reporting TA for the cell; and transmit TA report to the cell or to another cell associated with the second entity, based on detecting the condition. Optionally, the cell is a SCell and / or the other cell is a PCell. Optionally, the TA report is a TAR MAC CE. Optionally, the condition is based on an offset threshold; for example, the first entity transmits the TA report if the variation between a current estimate of the Timing Advance value and a last reported Timing Advance value is equal to or larger than a configured (e.g. predetermined) timing advance offset threshold. Optionally, the TA report comprises an indication of the cell (e.g. SCell index) and / or an increased TA field (e.g. the increased TA field is provided based on whether SCS larger than 15kHz are supported).

[00223] According to another example, there is provided a first entity (e.g. a UE) in a ATG network or a non-terrestrial network, wherein the first entity is configured to transmit, to a second entity, a TA report based on a preconfigured condition (e.g. default behaviour) being met, the preconfigured condition including one of a cell (e.g. SCell) associated with the second entity or cell group (e.g. SCG) associated with a third entity being established for the first entity, or performance (e.g. completion) of random access for the established cell or cell group. The TA report is transmitted to the cell or another cell (e.g. PCell) associated with the second entity, or to the third entity. Optionally, the preconfigured condition alternatively or additionally includes determining a change in a cell group established for the first entity, in which case the TA report is transmitted to an entity associated with a new cell group established for the first entity.

[00224] Figure 13 is a block diagram of an exemplary apparatus, or network entity, that may be used in examples of the present disclosure. The skilled person will appreciate said entity may be implemented, for example, as a network element on a dedicated hardware, as a software instance running on a dedicated hardware, and / or as a virtualised function instantiated on an appropriate platform, e.g. on a cloud infrastructure.

[00225] The entity 1300 comprises a processor (or controller) 1301, a transmitter 1303 and a receiver 1305. The receiver 1305 is configured for receiving one or more messages from one or more other network entities, for example as described above. The transmitter 1303 is configured for transmitting one or more messages to one or more other network entities, for example as described above. The processor 1301 is configured for performing one or more operations, for example according to the operations as described above.

[00226] Figure 14 is a flow diagram illustrating a method according to various examples of the present disclosure. The method is performed by a UE.

[00227] In operation S1410, the UE receives, from a first network entity, associated with at least one first cell, configuration information for establishing dual connectivity (DC) or carrier aggregation (CA), the configuration information including information on at least one second cell.

[00228] In operation S1420, the UE establishes the at least one second cell as at least one secondary cell (SCell) for CA or a secondary cell group (SCG) for DC, based on the configuration information. Establishing the at least one second cell comprises: applying a synchronization associated with the at least one first cell to the at least one second cell, or applying a synchronization based on first synchronization information included in the configuration information to the at least one second cell. It will be appreciated that establishing the at least one second cell may comprise additional operations.

[00229] Figure 15 is a flow diagram illustrating a method according to various examples of the present disclosure. The method is performed by a network entity.

[00230] In operation S1510, the network entity determines to establish at least one second cell as at least one secondary cell (SCell) for carrier aggregation (CA) or a secondary cell group (SCG) for dual connectivity (DC) for a user equipment (UE).

[00231] In operation S1520, based on determining a difference in synchronization between the at least one first cell and the at least one second cell, the network entity includes, in configuration information for establishing CA or DC to the UE, first synchronization information for a synchronization applicable for the at least one second cell.

[00232] In operation S1530, the network entity transmits, on the at least one first cell, configuration information for establishing CA or DC to the UE.

[00233] It will be appreciated that operations S1520 and S1530 may be combined, in an operation of the network entity transmitting on the at least one first cell, configuration information for establishing CA or DC to the UE, wherein, based on determining a difference in synchronization between the at least one first cell and the at least one second cell, the network entity is configured to include, in the configuration information, first synchronization information for a synchronization applicable for the at least one second cell.

[00234] It will be appreciated that, in each example / embodiment / aspect etc. described above, one or more features or operations may be omitted, modified or moved (e.g., to change the order of the features or the operations), if desired and appropriate. Additionally, one or more features or operations from any example / embodiment may be combined with features or operations from any other example / embodiment. In particular, regardless of whether or not a pointer towards a combination of features / examples is found herein, the present disclosure should be considered to include all combinations of two or more of the embodiments, examples etc. disclosed herein, and all combinations of two or more of the features disclosed herein.

[00235] The techniques described herein may be implemented using any suitably configured apparatus and / or system. Such an apparatus and / or system may be configured to perform a method according to any aspect, embodiment or example disclosed herein. Such an apparatus may comprise one or more elements, for example one or more of receivers, transmitters, transceivers, processors, controllers, modules, units, and the like, each element configured to perform one or more corresponding processes, operations and / or method steps for implementing the techniques described herein. For example, an operation / function of X may be performed by a module configured to perform X (or an X-module). The one or more elements may be implemented in the form of hardware, software, or any combination of hardware and software.

[00236] It will be appreciated that examples of the present disclosure may be implemented in the form of hardware, software or any combination of hardware and software. Any such software may be stored in the form of volatile or non-volatile storage, for example a storage device like a ROM, whether erasable or rewritable or not, or in the form of memory such as, for example, RAM, memory chips, device or integrated circuits or on an optically or magnetically readable medium such as, for example, a CD, DVD, magnetic disk or magnetic tape or the like.

[00237] It will be appreciated that the storage devices and storage media are embodiments of machine-readable storage that are suitable for storing a program or programs comprising instructions that, when executed, implement certain examples of the present disclosure. Accordingly, certain examples provide a program comprising code for implementing a method, apparatus or system according to any example, embodiment and / or aspect disclosed herein, and / or a machine-readable storage storing such a program. Still further, such programs may be conveyed electronically via any medium, for example a communication signal carried over a wired or wireless connection.

[00238] While the present disclosure has been shown, illustrated and described with reference to certain examples, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the disclosure.

[00239] The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

[00240] Annex - Examples of Specification text and / or changes based on the present disclosure There are now provided four examples of how various teachings of the present disclosure may be implemented in a technical specification, such as TS 38.331 (e.g. v18.0.0). In these examples, where the formulation “...OMITTED...” (or similar) is used, this is merely to indicate the omission of portions of the technical specification which are not necessary, in the specific example, for implementing said teachings. In these examples, the wording for implementing the teachings of the present disclosure is shown underlined and in bold text. Example #1 ----------------TS 38.331 V18.0.0---------------- - CellGroupConfig The CellGroupConfig IE is used to configure a master cell group (MCG) or secondary cell group (SCG). A cell group comprises of one MAC entity, a set of logical channels with associated RLC entities and of a primary cell (SpCell) and one or more secondary cells (SCells). For an NCR-MT, the CellGroupConfig IE is also used to provide the configuration of side control information for the NCR-Fwd access link. CellGroupConfig information element cellGrt'UpId rlo -Be are r T oAdil M-dLi a t CECtMLCM ( CL 1 i (1. .maxLC-1D) j 01 RLC-BearerConfig 1. .m-t L -II ’ LogioalChannelldentity ^pCellCcnfig PhysicalCellGroupConfig GIT:I SCellCcnfig {true}: . OMITTED ECellConfig ::= aCellIndex shell Conf igCoicimon sCellConfigDedicatcd :<<<<<<< ililiililililililit jssssstOsjsssss^ llllilllllllllllllllll :GsjSGSfi§af§S:sssssssssssssss ooMrpfUsrsHysHGygit ittllililililililil / S~rvingC~llConfig illiillililililili / iiPcgLii / gg L~ lit -t-t| K. t itlk -1 1 ' Illl-t lll.t ill I i-L 1’1 A ' f I Lr'ini ^IIE”-ili 1-it 1 iiBFE-11" -r -LIE’ctlu-iM h-H" t . , (llililililililililililililililill lmii-1 l~iitit4 lii± Li_t-il x_-tii^ {ELI HI—I i^utit lut Li^t} , :a£c£Cog^^ Conditional Presence Explanation ATG The field is mandatory present when configuring an SCell in ATG, otherwise it is absent. Example #2 ----------------TS 38.331 V18.0.0---------------- 5.3.5.3 Reception of an RRCReconfiguration by the UE The UE shall perform the following actions upon reception of the RRCReconfiguration, upon execution of the conditional reconfiguration (CHO, CPA or CPC), or upon execution of an LTM cell switch: . . . OMITTED . . . 1> else if the RRCReconfiguration message was received via SRB3 (UE in NR-DC): 2> if the RRCReconfiguration message was received within DLInformationTransferMRDC'. 3> if the RRCReconfiguration message was received within the nr-SCG within mrdc-SecondaryCellGroup (NR SCG RRC Reconfiguration): 4> if the scg-State is not included in the RRCReconfiguration message containing the RRCReconfiguration message: 5> if reconfigurationWithSync was included in spCellConfig in nr-SCG: 6> initiate the Random Access procedure on the PSCell, as specified in TS 38.321 [3]; 6> if the UE was configured with successPSCell-Config by the PCell or by the source PSCell: 7> perform the actions for the successful PSCell change report determination as specified in clause 5.7.10.7, upon successfully completing the Random Access procedure triggered for the reconfigurationWithSync in spCellConfig of the SCG; 5> else: 6> the procedure ends; 4> else: 5> perform SCG deactivation as specified in 5.3.5.13b; 5> the procedure ends; 3> else: 4> if the RRCReconfiguration does not include the mrdc-SecondaryCellGroupConfig'. 5> if the RRCReconfiguration includes the scg-Statc. 6> perform SCG deactivation as specified in 5.3.5.13b; 4> submit the RRCReconfigurationComplete message via SRB1 to lower layers for transmission using the new configuration; 2> else: 3> if the RRCReconfiguration includes the reconfigurationWithSync in spCellConfig for the SCG; and 3> if the UE was configured with successPSCell-Config'. 4> perform the actions for the successful PSCell change report determination as specified in clause 5.7.10.7, upon successfully completing the Random Access procedure triggered for the reconfigurationWithSync in spCellConfig of the SCG; 3> if the UE has successful PSCell change or addition information available in ParSuccessPSCell-Report and if the RPLMN is included in plmn-IdentityList stored in VarSuccessPSCell-Report, or 3> if the UE has successful PSCell change or addition information available in VarSuccessPSCell-Report and if the current registered SNPN is included in snpn-IdentityList stored in the VarSuccessPSCell-Report: 4> include successPSCell-InfoAvailable in the RRCReconfigurationComplete message; 3> submit Ate. RRCReconfigurationComplete message via SRB3 to lower layers for transmission using the new configuration; 1> else (RRCReconfiguration was received via SRB1): 2> if the UE is in NR-DC and; 2> if the RRCReconfiguration does not include the mrdc-SecondaryCellGroupConfig: 3> if the RRCReconfiguration includes the scg-State: 4> perform SCG deactivation as specified in 5.3.5.13b; 3> else: 4> perform SCG activation without SN message as specified in 5.3.5.13bl; 2> if the reconfigurationWithSync was included in spCellConfig of an MCG: 3> if ta-Report or ta-ReportATG is configured with value enabled and the UE supports TA reporting: 4> indicate TA report initiation to lower layers; 2> if the RRCReconfiguration message includes the nirdc-SecondarvCellGroupConfig with tnrdc-SecondaryCellGroup set to nr-SCG: 3> if ta-Report or ta-ReportATG is configured with value enabled and the UE supports TA reporting: 4> indicate TA report initiation to the SCG MAC entity; 2> submit the RRCReconfigurationComplete message via SRB1 to lower layers for transmission using the new configuration; 2> if this is the first RRCReconfiguration message after successful completion of the RRC reestablishment procedure: 3> resume SRB2, SRB4, DRBs, multicast MRB, and BH RLC channels for IAB-MT, and Uu Relay RLC channels for L2 U2N Relay UE, that are suspended; Example #3 ----------------TS 38.321 V18.0.0---------------- 5.4.8 Timing Advance Reporting The Timing Advance reporting procedure is used in a non-terrestrial network or an air to ground network to provide the gNB with an estimate of the UE's Timing Advance value (i.e., Eta as defined in the UE's TA formula, see TS 38.211 [8] clause 4.3.1). RRC controls Timing Advance reporting by configuring the following parameters: - offsetThresholdTA', timingAdvanceSR. A Timing Advance report (TAR) shall be triggered if any of the following events occur: - upon indication from upper layers to trigger a Timing Advance report; - upon configuration of offsetThresholdTA by upper layers, if the UE has not previously reported Timing Advance value to current Serving Cell; - if the variation between the current estimate of the Timing Advance value and the last reported Timing Advance value is equal to or larger than offsetThresholdTA, if configured. - if a PDCCH-order is triggered on SCell and UE is configured with ta-Report\ The MAC entity shall: 1 >if the Timing Advance reporting procedure determines that at least one TAR has been triggered and not cancelled: 2> if UL-SCH resources are available for a new transmission and the UL-SCH resources can accommodate the Timing Advance Report MAC CE plus its subheader as a result of logical channel prioritization: 3> instruct the Multiplexing and Assembly procedure to generate the Timing Advance Report MAC CE as defined in clause 6.1.3.56. 2> else 3> if timingAdvanceSR is configured with value enabled'. 4> trigger a Scheduling Request. NOTE: UL-SCH resources are considered available if the MAC entity has been configured with, receives, or determines an uplink grant. If the MAC entity has determined at a given point in time that UL-SCH resources are available, this need not imply that UL-SCH resources are available for use at that point in time. A MAC PDU shall contain at most one Timing Advance Report MAC CE, even when multiple events have triggered a Timing Advance report. The Timing Advance Report MAC CE shall be generated based on the latest available estimate of the UE's Timing Advance value prior to the MAC PDU assembly. All triggered Timing Advance reports shall be cancelled when a MAC PDU is transmitted and this PDU includes a Timing Advance Report MAC CE. Example #4 ----------------TS 38.321 V18.0.0---------------- 5.4.8 Timing Advance Reporting The Timing Advance reporting procedure is used in a non-terrestrial network or an air to ground network to provide the gNB with an estimate of the UE's Timing Advance value (i.e., Eta as defined in the UE's TA formula, see TS 38.211 [8] clause 4.3.1). RRC controls Timing Advance reporting by configuring the following parameters: - offsetThresholdTA', timingAdvanceSR. A Timing Advance report (TAR) shall be triggered if any of the following events occur: - upon indication from upper layers to trigger a Timing Advance report; - upon configuration of offsetThresholdTA by upper layers, if the UE has not previously reported Timing Advance value to current Serving Cell; - if the variation between the current estimate of the Timing Advance value of a serving cell and the last reported Timing Advance value to the same serving cell is equal to or larger than offsetThresholdTA, if configured. The MAC entity shall: 1 >if the Timing Advance reporting procedure determines that at least one TAR has been triggered for a serving cell and not cancelled: 2> if UL-SCH resources are available for a new transmission and the UL-SCEI resources can accommodate the Timing Advance Report MAC CE plus its subheader as a result of logical channel prioritization: 3> instruct the Multiplexing and Assembly procedure to generate the Timing Advance Report MAC CE as defined in clause 6.1.3.56. 2> else 3> if timingAdvanceSR is configured with value enabled'. 4> trigger a Scheduling Request. NOTE: UL-SCEI resources are considered available if the MAC entity has been configured with, receives, or determines an uplink grant. If the MAC entity has determined at a given point in time that UL-SCH resources are available, this need not imply that UL-SCH resources are available for use at that point in time. A MAC PDU shall contain at most one Timing Advance Report MAC CE per serving cell, even when multiple events have triggered a Timing Advance report. The Timing Advance Report MAC CE shall be generated based on the latest available estimate of the UE's Timing Advance value prior to the MAC PDU assembly. All triggered Timing Advance reports per serving cell shall be cancelled when a MAC PDU is transmitted and this PDU includes a Timing Advance Report MAC CE. Acronyms and Definitions (as may be used herein) 3GPP 3rd Generation Partnership Project NW Network 5G 5th Generation NWDAF Network Data Analytics Function 5GC 5G Core QAM Operations and Management 5QI 5G QoS Identifier OS Operating System 5GS 5G System PCF Policy Control Function 5GSM 5G System Session Management PCC Policy and Charging Control 5GMM 5G System Mobility Management PCO Protocol Configuration Options AF Application Function PDR Packet Detection Rule Al Artificial Intelligence PDU Protocol Data Unit AIML Artificial Intelligence / Machine PMF Performance Measurement Function Learning PRS Positioning Reference Signal AM Acknowledged Mode PRU Positioning Reference Unit AMF Access and Mobility Management PSA PDU session anchor Function QFI QoS Flow Identifier (ID) AS Application Server QoE Quality of Experience ASP Application Service Provider QoS Quality of Service ATSSS Access Traffic Steering Switching RACH Random Access Channel & Splitting RAN Radio Access Network AUSF Authentication Server Function RAT Radio Access Technology CDRX Connected Mode Discontinuous RLC-AM Radio Link Control Acknowledge Reception Mode CSI Channel Status Information RLC-UM Radio Link Control Unacknowledge DCAF Data Collection Application Mode Function RSD Route Selection Descriptor DNAI Data Network Access Identifier SA Standalone DNN Data Network Name SBA Service-Based Architecture DNS Domain Name Server SBI Service-Based Interface DRB Data Radio Bearer SCEF Service Capability Exposure Function eNB Evolved Node B SCP Service-Based Communication Proxy EPS Evolved Packet System SCTP Stream Control Transmission FQDN Fully Qualified Domain Name Protocol GBR Guaranteed Bit Rate SDAP Service Data Adaptation Protocol GMLC Gateway Mobile Location Centre SDU Service Data Unit gNB Next generation Node B SIM Subscriber Identity Module GPSI Generic Public Subscription SLA Service Level Agreement Identifier SM Session Management IAB Integrated Access and Backhaul SMF Session Management Function ID Identity / ldentifier SN Secondary Node lloT Industrial Internet of Things S-NSSAI Single Network Slice Selection IMEI International Mobile Equipment Assistance Information Identities SRS Sounding Reference Signal IP Internet Protocol SSC Session and Service Continuity l-SMF Intermediate SMF SUPI Subscription Permanent Identifier LMF Location Management Function TAI Tracking Area Identity MA-PDU Multiple Access PDU TE Terminal Equipment ML Machine Learning TM Transparent Mode MME Mobility Management Entity TS Technical Specification MN Master Node UDM Unified Data Manager MNO Mobile Network Operator UDR Unified Data Repository MPTCP MultiPath TCP UE User Equipment MT Mobile Termination UL Uplink NAS Non-Access Stratum UM Unacknowledged Mode NEF Network Exposure Function UP User Plane NRF Network Repository Function UPF User Plane Function NG-RAN Next Generation Radio Access URLLC Ultra-Reliable and Low-Latency Network Communication NG-eNB Next Generation eNB URSP UE Route Selection Policy NSA Non-Standalone XRM Extended Reality and Media NSSF Network Slice Selection Function

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