Methods for mobile integrated access and backhaul inter and intra radio access technology mobility

Abstract

A method is provided of performing inter-RAT mIAB mobility by a UE of a communications network, the method comprising receiving inter-RAT mIAB assistance information from a node of the network compris

Description

BACKGROUND Field Certain examples of the present disclosure provide various techniques relating to methods for mobile integrated access and backhaul (mlAB) inter and intra radio access technology (RAT) mobility, for example methods for signalling mlAB idle mode / inactive mode inter-RAT and intra-RAT mlAB assistance information, for example within 3rd Generation Partnership Project (3GPP) 5th Generation (5G) New Radio (NR) and NR-based relay networks. Description of the Related Art Integrated Access and Backhaul (IAB) In 3rd Generation Partnership Project (3GPP) 5th Generation (5G) New Radio (NR), Integrated Access and Backhaul (IAB) is a technique for providing wireless backhaul as an alternative to a fibre backhaul network. An IAB network comprises IAB nodes, at which wireless resources are shared between wireless backhaul and access links. By means of such a configuration, it is possible to install nodes without the necessity of providing a fibre data connection, thereby allowing speedy and simple roll out of network coverage to locations where no such data connection is available or possible. Due to the limited coverage area of an IAB node, the backhaul network is typically implemented as a multi-hop network with backhaul traffic traversing multiple IAB nodes. Figure 1 shows a two-hop IAB network as described in 3GPP NR Rel-16 and further enhanced in Rel-17. 3GPP 5G Release 16 was the first release comprising the IAB feature. Release 17 comprised enhancements to the Release 16 baseline and is now frozen. Work on Release 18 is currently underway to develop and improve features relating to IAB relative to previous Releases, most notably the mobility of IAB nodes. The assumption in previous Releases was that the IAB nodes are stationary. Mobile IAB Mobile IAB is a 3GPP Release 18 work item whose focus is to enhance IAB to enable mobile IAB. The deployment purpose of mobile IAB is to allow for lAB-Distributed Units (DUs) to provide connectivity on trains, buses etc. Mobile IAB does not support Dual Connectivity (DC) options (i.e. Evolved Universal Terrestrial Radio Access (E-UTRA) NR (EN) - DC or New Radio (NR) - DC). The focus is to provide good mobility support. The Work Item Description mentions the following enhancements [RP-222671, Mobile IAB (Integrated Access and Backhaul) for NR, Qualcomm, RAN#97, September 2022]: • Define procedures for migration / topology adaptation to enable lAB-node mobility, including inter-donor migration of the entire mobile lAB-node (full migration). [RAN3, RAN2], o the mobile lAB-node can connect to a stationary (intermediate) lAB-node, optimizations specific to the scenarios where the mobile lAB-node connects to a stationary (intermediate) lAB-node, or where it directly connects to an IAB-donor-DU are de-prioritized, o the mobility of dual-connected lAB-nodes is down-prioritized. • Enhancements for mobility of an lAB-node together with its served User Equipments (UEs), including aspects related to group mobility. No optimizations for the targeting of surrounding UEs. [RAN3, RAN2], • Mitigation of interference due to lAB-node mobility, including the avoidance of potential reference and control signal collisions (e.g. PCI, Resources Access Channel (RACH)). [RAN3, RAN2], Long Term Evolution (LTE) Inter-RAT Mobility Connected Mode Performing handover from NR to Evolved Universal Telecommunications System Terrestrial Radio Access Network (E-UTRAN) is done via the Radio Resource Control (RRC) message MobilityFromNRCommand. The RRC message MobilityFromNRCommand contains the handover command based on the specific RAT that the UE shall perform mobility to. In the case of handover to E-UTRAN the message contains the E-UTRAN RRCConnectionReconfiguration message. This can be seen in Figure 2. Inter-RAT mobility procedures are also invoked when a so-called inter-core network (CN) mobility (or sometimes called inter-system mobility) is performed. This occurs when mobility is performed between two cells with different core networks. One such example is when performing mobility from E-UTRAN Evolved Packet Core (EPC) to E-UTRAN 5G Core (5GC) or the reverse direction. In this case, the mobility is triggered via the RRCConnectionReconfiguration message. One example can be seen in Figure 3. When a UE in E-UTRAN operates in 5GC, the UE uses NR PDCP and SDAP instead of LTE PDCP (i.e. no SDAP). Idle Mode Inter-RAT cell reselection is supported in RRC idle mode and RRC inactive mode for both LTE and NR. In LTE and NR, there are conditions for measurements supporting inter-RAT cell reselection. If the priority of the frequency is higher than the current frequency, the UE shall always perform measurements on the inter-RAT frequency. If the priority of the inter-RAT frequency is equal or lower, the measurements are performed if the serving cell signal strength fulfils some specific thresholds, otherwise the UE shall perform measurements on the inter-RAT frequency. For reselecting to an inter-RAT cell, there are also rules. In order for a higher priority NR frequency to be selected, the cell signal strength needs to be above a configured threshold during a time interval TreselectionRAT. The cell reselection to an equal priority cell is based on ranking for intra-frequency cell reselection. Finally the inter-RAT cell reselection to a cell on a lower priority frequency is done when the serving cell signal quality is below a threshold and the neighbouring cell signal strength is above a threshold for a time interval TreselectionRAT. For all of the cases, in order to camp on a cell, the cell needs to fulfil the cell selection criteria S. In NR, if a UE selects an inter-RAT cell while in RRC_INACTIVE, the UE transitions from RRC_INACTIVE to RRC_IDLE. In some cases, for the cell reselection, there is a requirement that at least 1 second shall have elapsed since the UE camped on the current serving cell before reselecting to a new cell. In idle mode for inter-RAT mobility there is the following system information broadcasted: System Information Block (SIB) 5 is broadcasted in an NR cell to give cell re-selection parameters and information about inter-RAT E-UTRAN frequencies. The SIB gives information such as: o carrier frequency lists of E-UTRA frequencies and E-UTRA cells; o T-ReselectionEUTRA; o cell reselection parameters such as priorities, selection thresholds, etc., and o cell lists, SIB24 is broadcasted in an E-UTRAN cell to perform inter-RAT measurements and cell reselection of an NR cell. This gives information important about an NR cell required to measure an NR cell, such as: o carrier frequency lists of NR frequencies; o cell reselection parameters such as priorities, selection thresholds, etc.; o T-ReselectionNR, which is the cell reselection timer value, if a UE is camping on an E-UTRA cell, in order to reselect to an NR cell, the Squal needs to be above the ThreshX, HighQ for a longer duration that T-ReselectionNR; ■ the timer values are 0, 1,2, ..., 7 seconds, o NR-specific parameters needed to detect and measure NR cells: ■ SMTC; ■ SSB information such as SSB SCS, SSB position, SSB Measurement Timing Configuration (SMTC), o cell lists. RRC Release NR RRC Release One way to enter RRC idle mode or RRC inactive mode is by the network releasing the UE through the RRC release procedures. The RRC release procedures are initiated when the UE receives a RRCRelease message from the gNB. This can be seen in Figure 4. The RRCRelease message sent from the gNB may in turn have been triggered by the either the gNB or the Access and Mobility Management Function (AMF). This can for instance be due to any of the following reasons: • load balancing; • re-direction (both in RRC idle and RRC inactive modes) to other frequencies or RATs; • UE context release triggered by the AMF (CN), for instance due to no Downlink (DL) or Uplink (UL) data in the buffer; • suspend indication to send the UE to RRC inactive; • failure to retrieve UE context when UE resumes RRC connection mode from RRC inactive mode. The RRC release message may for instance contain any of the following information elements: • redirectedCarrierlnfo - information on carriers to re-direct to, which may be inter or intra-RAT frequencies; • cellReselectionPriorities - cell reselection priorities - these may be specifically configured for the UE in the RRCRelease message; • suspendConfig - configuration for RRC inactive; • depriontisationReq-, • waitTime; • measIdleConfig - measurement configuration for idle mode, used to measure and store measurement information to be reported to the network when re-connecting; • sdtConfig - configurations for Short Data Transmissions (allows UE to send a usually smaller amount of data in RRC inactive mode); • srs-PosRRC-lnactive - SRS configuration to be used for RRC inactive positioning. Includes the potential following timers: - waitTime (T302) - timer to bar the UE from attempting to access; - T320 - how long the cell configured cell reselection priorities shall be active; - T380 - timer-based RAN Notification Area Update. LTE RRC Release RRC Connection Release is the procedure that is used to send the UE to RRC idle mode or to RRC idle mode with suspend connection. This is seen in Figure 5. In RRCConnectionRelease (E-UTRAN / LTE version) the following can be signalled: • Release cause o loadbalancingTAUrequired o other o cs-FallbackHighPriority o rrc-Suspend • RedirectedCarrierlnfo o Contains frequencies of different RATS such as EUTRA, GERAN, utra, cdma2000, NR • idleModeMobilityControlInfo o frequency priority list which signals different carrier frequencies and their cell reselection priority for different RATs o T320 which gives the time the frequency priority list is active • celllnfoList o provides redirection information for one or more cells on inter-RAT frequencies, this information provides cell IDs, carrier frequencies, and system info for cells on other RATs • MeasIdleConfig o conveys information about measurements to be performed in idle mode, this is used for the purpose of performing faster Carrier Aggregation establishment • Alternative frequency priorities o tells the UE to apply alternative cell reselection priorities • Release idle mode measurement config o indicates that the UE shall release the idle / inactive measurement configuration, if it has been configured, used for early CA setup (CA / DC enhancements). A first issue with mlAB is that macro cells are large, mlAB cells are smaller. Due to the nature of mlAB cells moving, and potentially moving unpredictably, it may not always be easy to broadcast the correct mlAB information at the right time. This is especially important as system information, and in particular cell reselection parameters, usually do not change throughout long periods. Thus there may need to be more tools for the UE to signal mlAB cell assistance information in a more dedicated manner. A deployment example can be found in Figure 6, where an mlAB cell only goes through a very small part of a larger macro cell. A second issue with mlAB is that E-UTRAN / LTE / 4G and NR / 5G have a very close relationship with mobility between the two RATs designed to be efficient and close to seamless, compared to mobility with other RATs. Without methods to perform efficient idle mode mobility from E-UTRAN to NR mlAB cells, there may not be much benefit in mlAB as most real-life deployments heavily rely on both E-UTRAN and NR cells. The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with respect to the present invention. SUMMARY It is an aim of certain examples of the present disclosure to address, solve and / or mitigate, at least partly, at least one of the problems and / or disadvantages associated with the related art, for example at least one of the problems and / or disadvantages described herein. It is an aim of certain examples of the present disclosure to provide at least one advantage over the related art, for example at least one of the advantages described herein. Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description taken in conjunction with the accompanying drawings. In one aspect of the invention there is provided, in a communications network, a method of the network signalling inter-RAT mlAB assistance information or intra-RAT mlAB assistance information to a UE of the network for mlAB inter-RAT mobility or intra-RAT mobility. The method may comprise the UE being configured with intra-RAT mlAB cell assistance information in a NR mlAB cell when the UE is released to RRC idle mode or RRC inactive mode. The method may comprise the UE being configured with inter-RAT mlAB cell assistance information in an E-UTRA cell when the UE is released to RRC idle mode or RRC inactive mode. In one aspect of the invention there is provided a communications network which signals inter-RAT mlAB assistance information or intra-RAT mlAB assistance information to a UE of the network for mlAB inter-RAT mobility or mlAB intra-RAT mobility. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 illustrates a two-hop I AB network, taken from TR 38.874 “Study on Integrated Access and Backhaul”, V16.0.0, December 2018, Figure 1 illustrates a mobility from NR to E-UTRAN procedure, Figure 2 illustrates connected mode mobility, Figure 3 illustrates a RRC release procedure, Figure 4 illustrates RRC Connection Release procedures, Figure 5 illustrates a deployment scenario with macro cells and mlAB cells on a train travelling in a limited area of the macro cell deployment, Figure 6 illustrates eNB signalling inter-RAT mlAB cell assistance information, Figure 7 illustrates indicating mlAB cell presence and then gNB choosing to broadcast mlAB cell assistance information, Figure 8 illustrates releasing a UE and configuring it with mlAB inter-RAT prioritization information or mlAB cell assistance information for intra-RAT and inter-RAT cases, Figure 9 illustrates an example of how to configure a UE with mlAB prioritization information or mlAB cell assistance information, Figure 10 illustrates another example of how to configure a UE with mlAB prioritization information or mlAB cell assistance information. DETAILED DESCRIPTION The following description of examples of the present disclosure, with reference to the accompanying drawings, is provided to assist in a comprehensive understanding of the present invention, as defined by the claims. The description includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the examples described herein can be made. 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. For example, the functionality of an IAB node in the examples below may be applied to any other suitable type of entity performing functions of a network node. The skilled person will appreciate that the present invention is not limited to the specific examples disclosed herein. For example: • The techniques disclosed herein are not limited to 3GPP 5G. • One or more entities in the examples disclosed herein may be replaced with one or more alternative entities performing equivalent or corresponding functions, processes or operations. • One or more of the messages in the examples disclosed herein may be replaced with one or more alternative messages, signals or other type of information carriers that communicate equivalent or corresponding information. • One or more further elements, 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. To satisfy extremely high data rate requirements, the 3GPP 5G NR standard utilises communication frequencies in a relatively high range, from 30 GHz to 300 GHz, corresponding to wavelengths in the millimetre (mm) range (mmWave communication). Such mmWave communication provides a large available bandwidth and high transmission speeds. However, problems with mmWave communication include severe signal path loss and low penetration, resulting in a relatively short transmission range. This in turn requires a greater density of base stations deployment. Certain examples of the present disclosure provide a network or wireless communication system comprising a first network entity and a second network entity according to any example, embodiment, aspect and / or claim disclosed herein. Certain examples of the present disclosure provide a computer program comprising instructions which, when the program is executed by a computer or processor, cause the computer or processor to carry out a method according to any example, embodiment, aspect and / or claim disclosed herein. Certain examples of the present disclosure provide a computer or processor-readable data carrier having stored thereon a computer program according to the preceding examples. The disclosure relates to additional methods for signalling mlAB idle mode I inactive mode inter-RAT mlAB assistance information or intra-RAT mlAB assistance information. In the description below, the example embodiments may apply to eNBs, gNBs, en-gNBs, NG-RANs or NG-eNBs. For instance, in some example embodiments, the disclosure may be for an eNB, but it may also apply for an NG-eNB (an eNB is connected to EPC, while an NG-eNB is connected to 5GC). In some example embodiments, there may also be methods explicitly for an NG-eNB, en-gNB, gNB, or NG-RAN. mlAB Inter-RAT Idle Mode and Inactive Mode Mobility In order for a network to get full benefit of mlAB cells, inter-RAT cell reselection from E-UTRAN (non-mlAB as there is no IAB E-UTRAN cell) to mlAB NR is supported in this disclosure. In order for a UE to efficiently perform inter-RAT cell reselection from E-UTRAN to an NR mlAB cell, the network may signal inter-RAT mlAB assistance information in an E-UTRAN node about potential mlAB cells or frequencies. An example of this can be found in Figure 7. The inter-RAT mlAB assistance information that is signalled on an E-UTRAN node about an NR mlAB cell may for instance include the following fields: - the presence of mlAB cells on a frequency, o this can be a flag that indicates that there are mlAB cells on the frequency and if an mlAB cell is detected, the UE may prioritize the frequency; a list of mlAB cells; mlAB-specific TreselectionRAT (TreselectionRAT-mlAB), o this can for instance be shorter compared to the TreselectionNR, which allows for a faster reselection from an EUTRA cell to an NR mlAB cell, this can be general to any mlAB cell, or be specific to a frequency where there are mlAB cells; reselection-thresholds specific to mlAB cells, o potential examples include q-RxLevMin (a minimum Rx level in order for a cell to fulfil S criteria), threshX-High (a threshold for high priority frequencies), threshX-Low (a threshold for low priority frequencies), threshX-Q, o these can be utilized only for the mlAB cells on the frequency. The above inter-RAT mlAB assistance information fields may, for instance, be signalled in a System Information Block (SIB), where the most suitable SIB may be SystemlnformationBlockType24. Some of the inter-RAT mlAB assistance information fields, such as a list of mlAB cells, the presence of mlAB cells on a frequency and similar, may be signalled per frequency. Some of the fields, such as mlAB-specific TreselectionRAT, may be signalled for the full inter-RAT cell reselection parameters. This may also be signalled in a release message. A specification example of this can be found in Specification Example #1, below. As the area where it is relevant to perform inter-RAT idle mode mobility may be significantly smaller than the size of a mlAB cell, there may be further information which is signalled, indicating when and where the cell inter-RAT mlAB assistance information is to be applied, or when mlAB cells shall be detected. This can be area information or time information. For the area information, this can be expressed as a set of geographical coordinates along with radii. For the time information, this can be a single time instance, or a time window. The time and area information may be signalled independently, or sent together. In one aspect of the disclosure, the restriction that a UE shall wait 1 second before reselecting another cell is not required for performing inter-RAT reselection to a mlAB cell. In another aspect of the disclosure, if there are multiple cells fulfilling the criteria for inter-RAT cell reselection, and only one of the cells is an mlAB cell, the UE may select the mlAB cell. This means that in the inter-RAT cell reselection, the mlAB cell may have higher priority. For performing the methods whereby a UE identifies an inter-RAT cell as an mlAB cell, either the cell inter-RAT mlAB assistance information may be used, which is signalled in SIB24 as an example, or the UE determines this assistance information based on an indication of a specific neighbouring cell in SIB1. An example of how broadcasting of the inter-RAT mlAB assistance information may be used is that, when there are no mlAB cells nearby, the network may not broadcast the specific system inter-RAT mlAB assistance information, for example in SIB24, and when the network knows that there may be mlAB cells incoming, the network may start broadcasting the system inter-RAT mlAB assistance information, for example using SIB24. Starting to broadcast the system inter-RAT mlAB assistance information may be triggered by a neighbouring cell, or via OAM. If triggered by a neighbouring cell, this can be done via a message over Xn, using messages such as NG-RAN NODE CONFIGURATION UPDATE or any other new messages. An example of this can be seen in Figure 8. Configuring mlAB Cell Assistance via RRC Release As explained in some of the mlAB issues above, it may be difficult to broadcast appropriate mlAB cell assistance information. In one aspect of the disclosure, a UE may be configured with intra-RAT mlAB cell assistance information in a NR mlAB cell when the UE is released to RRC idle mode or RRC inactive mode. The UE may be configured with the intra-RAT mlAB cell assistance information from a NR gNB. The UE may be configured with the intra-RAT mlAB cell assistance information in, for example, an RRC message, such as a RRCRelease message. Based on this intra-RAT mlAB cell assistance information, the UE may then connect to the NR mlAB cell. A general figure of this can be seen in Figure 9 and a specification example can be seen in Specification Example #3, below. In another aspect of the disclosure, a UE may be configured with inter-RAT mlAB cell assistance information in an E-UTRA cell when the UE is released to RRC idle mode or RRC inactive mode. The UE may be configured with the inter-RAT mlAB cell assistance information from an E-UTRAN eNB. The UE may be configured with the inter-RAT mlAB cell assistance information in an RRC message, such as a RRCConnectionRelease message. This can also be seen in Figure 9 and a specification example can be found in Specification Example #2, below. The UE may, for instance, be re-directed to an mlAB cell via inter-RAT mlAB cell assistance information or the intra-RAT mlAB cell assistance information in a RRCConnectionRelease message. This may make sense if there is no X2 interface orXn interface (i.e. an inter-node interface) in between the mlAB cell and the NR / E-UTRA cell. In one aspect of the disclosure, the UE may be configured with mlAB cell assistance information when the UE is “re-directed” to another frequency and / or inter-RAT. In the redirect case, there may be only a single frequency, and the UE then performs cell selection based on this information. The re-direction configuration may similarly include the PCI of mlAB cells, or be a flag indicating that the UE shall prioritize mlAB cells when re-directing, i.e. perform cell selection. In one aspect of the disclosure, the UE may be configured with mlAB cell assistance information when the UE is configured with dedicated priorities. The mlAB cell assistance information may be inter-RAT mlAB cell assistance information or intra-RAT mlAB cell assistance information. In a further aspect of being configured with dedicated mlAB cell assistance information via a RRC Release message, a T320 timer may be shorter. The T320 timer governs how long the dedicated priorities are used. In mlAB, since a mlAB cell moves, it may be problematic for network performance to maintain such mlAB cell assistance information for long as this may become outdated. In another aspect, a separate timer may be introduced for the inter-RAT mlAB cell assistance information. This timer may allow the network to configure a significantly shorter duration or a potentially longer duration for the mlAB cell assistance information. The inter-RAT mlAB cell assistance information or intra-RAT mlAB cell assistance information in a RRCConnectionRelease message can be a part of the following configurations: Redirection Info (E-UTRAN version) / RedirectedCarrierlnfo (NR version), - Idle mode control information (E-UTRAN) - this example can be seen in Example #2 below, CellReselectionPriorities (NR). For a gNB or an eNB configuring a UE with intra-RAT mlAB cell assistance information, an example of how the above aspects of the disclosure can be used can be as seen in Figure 10. In this example, the gNB may first configure the UE to measure mlAB cells in connected mode. This may be potentially for the purpose of eventually performing a handover to one of the mlAB cells. After having reported some measurements, the UE may not have any more DL or UL traffic, thus triggering the network to release the UE to RRC idle mode or RRC inactive mode. Since the gNB has received measurements that there are mlAB cells, the gNB may configure the UE with mlAB cell assistance information. In another example, a gNB may receive an mlAB on-board indication in RRC connected mode. Thereafter the network may configure a UE with mlAB prioritization information or intra-RAT mlAB cell assistance information in. The UE may be configured, for example, in an RRC Release message. The UE on-board indication is a concept introduced during the 3GPP Rel-18 mobile I AB discussions. This can be seen in Figure 11. In another aspect of the disclosure, the UE may send an indication to the network that it wants to connect to an mlAB cell. This may done via an mlAB-Preferencelndication message. This message can be configured by the network via otherConfig (which may be sent via a RRCReconfiguration message) and then sent in the UL via UE assistance information (RRC message U EAssistancel nformation). The non-mlAB gNB may also determine, based on factors such as UE position, history etc, that it is a high probability that the UE needs to be configured with mlAB cell assistance information. When the UE is released from RRC connected mode to RRC idle mode or RRC inactive mode, the UE may be required to first perform cell selection (not cell reselection). In an aspect of this disclosure, when a UE is released and performs cell selection, the UE may prioritize any mlAB cell in a cell selection algorithm. This is important as the cell selection algorithm normally does not have priorities - it only considers cells that are suitable or not. As another aspect, if a re-direction or a connection to an mlAB cell results from a UE being released, if the UE is barred from access to an mlAB cell during a time interval, for example a waitTime (such as measured by barring timer T302), the UE may consider the time interval, waitTime, to apply to all mlAB cells. This may help with overload cases, where, for instance, a set of mlAB cells may be overwhelmed with active mobility (handovers in RRC connected mode), as well as idle mode mobility via RRC release and idle mode mobility (i.e. cell reselection) based on broadcasted configurations. Considering the time interval measured by the T302 timer to apply to mlAB cells may also be performed when a UE camps on and then connects to the mlAB cells (i.e. without triggering from RRC release message). The barring may also occur both from receiving a RRC Release message and receiving a RRC Reject message. Specification Examples Example #1 Specification changes are shown in bold. 36.331 Release 17 V17.5.0, June 2023 SystemlnformationBlockType24 The IE SystemlnformationBlockType24 contains information relevant for inter-RAT cell reselection (i.e. information about NR frequencies and NR neighbouring cells relevant for cell reselection), which can also be used for NR idle / inactive mode measurements. The IE includes cell reselection parameters common for a frequency. SvstemlnformationBlockType24 information element RAiiASHRSRAjW 'iapxiex’FxeqLaa tFA-cl5 t-Ree elect xcxifF-ci; |||||||||||||i||rl|||||||||||||||^| lat eUcnCrit i callr.te.'ioicci 11 - 111 -11 .. 'll-- i >i1 II 1 ' 1 I I I - I 1 I .... ' 11. - J iillBiililiisssilB 11, [[ carrlerFreqListNR-vlSxy ]] PE-FFEF-FE | 1 ? c c 1 e x F x e q L1 a 111R - x 1F 1-Aee election, 1PTI01IAL, — Fee? OR Ftee?Et at e Fc ale Facto t= "PTH>IIAL, Fee? -FA -X-IEF .3TRI1I-3 oPTIOHAL, * 1 1- i - q 1 ,i , 1 I II-.- 11 .-PT 1tOI -1, RiRifiOSiAAF fiaFoReEiRRRRERRRRRRRRRRR:? -PT 1 <>11: 1 — ’, ' - । >R iiiiiiexBiiiiiiiiiiiiiiiiii 1 PTIOIIAL -- F-es OR CarrierFreqListNR-vlSxy OPTIONAL — Need OR axxx = xFxeqLx.-,tl,R-ci F :: FEoEElIFE i ri i' rFr: , j I, i. 111 '. :: : 'El.>1 El 1'" a i r i >i Fi <।; E i. I E- :: :’El,»IEE'.': O®B:isRiilililK8RFKgR<iiEi<<0F>i®aARiiO F. ■ । 1 . . III I Fl [ >) i ■’ , ■ i I- i t ■ , । I I R — | 1 i I . . in t I 1 >[ I I <•' >--1 Fi - qlll-.-. 1 iRRiRBBRRRlRRRRRRRRlIlsRRl CarrierFreqListNR-viexy ::= SEQUENCE (SIZE (1..maxFreq)) OF CarrierFreqNR-vl8xy FaxxiexFxeqllR-xli ::= c axxiexFxe'q-Ei i mult iEaii-ilnf. lie t-xl F uu 11 I 11 iu> 11 u I .: X ,-i 1 ‘ in-- i.:T 1 in 1 ir I- ’ 1 :- : 1 Jul - ' H I 1 • I If ■ ■':: t.-1 — i I 1 .--KF:' I -IO i.- f ■ : . -11' RFROl cellReselecti : ;.Rt: ritc-xl F FER IFF IE . A-AFF'-’Fal uelTR-xl F, 11. It iFxequen ?1E Uliilla tl'F . .. : 11 '1 '-’qi e -I i, -., I:, it u ill J ' ' >-"'I -111-:-1 1 1 “■ 1" ARTER [I II OF, l-ll • ■' 1 -I E <Ji u - m- 111 -1 . .'eiiReselect ionPciotit v OFTIO1IAL, — Fee: OF 'jJ'T I'Jll- 1,, — ' 'Ji. i ’I T H ’ll- 1,, — I O’ 1 'J, 111 'In) , ■1'T f> ill; I,, • -. : ■ • -PTIolIAL, — ----- i’P OR High- w-ri: EBE ■ । rji i.'. । 1 o .1 6’d u' i i 1' ,--i ;--; 7' -,6 -; 0 / 1.1 T i 6 — -. L 7 T a a o h J — A ~ A ~ A 7 , 1 - — _ H A J iZ UL- A 1 -4 --4 :'O 11-llb l-r!5 11 F f -F 0 . . -2 J >r -i :.- k-1 1 ••-d ..a,। t iib-i 11 bbbbOR f-M..-1 ’! OGLEAtl, ?::F 3-Iridez_CellQij alUR-rl 1 uldLi^tHR-rl2 QPTIO1IAL, •-rTTolI-'L, 01 'T f (. 4'1 01 :, -- 'i T L' 'II 'PET 101 LAL, zpTIRI I AL, -- 1- ' - <>R 111' ?. OP oi OR OR ..., 7:7:777667 multiEHi j O = -e. R-T 17-: ;- iieed OR |g|gi||77777||||7 "LiatllR-vl 5 5u :-:Li£-tlIR-EUL-vl55e |Es|||||||||||l|:| ll 7B|7077O77O7777|7OBO 7l77O707O77l777O77l®|: t 2-7:113 3 c ure-rl 1 :? OPTIOIIAL, OPT 101 LAL, OPT 101 JAL OR OR -,7-1 it 1'- ql IK-vV- I I :: ,':ilil 7 ’ -11 P— rl 1 7 s b-Po s i t i o nQ 71-0: OharedOpeutrumJ sll z r-d> ^11L„ - ^-Fhnadcp-rtrum 77 7 7 771:777077^ ;.’EyUEiK'E ( ii- lil 1R-11 > :16|| 1 B - rie El IC! A :-1 J 'RR-t 1 <-7B7O7777d707RRd7d77O7B7 11 ;--e d:AllLi3tIIR-rll RJ27EZ- {true} a'TlNiM,, rll OPTIONAL, OPT 101 LAL, ||6|| 717101111 -- R- : : ( iR Oli ’1" :: 6iiii777:O77777:7Osr777 = cEQUEHCE 1 I I 1,1.:1 -1 I 1 HR- .- 01:7-loi-1 11.1 a : • — ».- ~ CI: 1 11 r m rl- r< ' |11K-’ '1 :: 6666670777777770^7717 rd -E . Iti 1 ’1- • 3--1-1 ' :.:11: nllR-rl^ II dOuOTEP [RHl-Ob OPTIONAL, -- LRAi OR CarbierFreqNR-vlSxy ::= SEQUENCE { mobilelAB-Assistancelnfo-rlB MobileIAB-AssistanceInfo-rl8 OPTIONAL — Need OR [ SystemlnformationBlockType24 field descriptions i aHowedCeHListNR ; List of allow-listed neighbouring NR cells. i ; camerFreqListNR i List of carrier frequencies of NR carriers. These frequencies correspond to GSCN values as specified in TS 38.101 i i

[85] , If the carrierFreqListNR-v1610 is present, it contains the same number of entries, listed in the same order as in i ; the camerFreqListNR (without suffix). i i ceilReseieciionPriorlty i The field concerns the absolute priority of the concerned carrier frequency as used by the cell reselection procedure, i i Corresponds with parameter "priority" in TS 36.304 [4], i ; deriveSSB-indexFromCeii i The field indicates whether the UE may use, to derive the SSB index of a cell on the indicated SSB frequency and i ; subcarrier spacing, the timing of any detected cell with the same SSB frequency and subcarrier spacing. If this field is i I set to TRUE, the UE assumes SFN and frame boundary alignment across cells on the same NR carrier frequency as i i specified in TS 36.133

[16] .______________________________________________________________________________________________________i ; highSpeedCamertiR i If the field is present, the UE shall apply the enhanced inter-RAT NR measurement requirements to support high i I speed up to 500 km / h as specified in TS 36.133

[16] to the NR carrier. i maxRS-indexCeUQuai i Number of SS blocks to average for cell measurement derivation. Corresponds to the parameter nrofSS- I i BlocksToAveraqe in TS 38.304

[92] .____________________________________'_____________________________________________[ i measTimingConfig i Used to configure measurement timing configurations, i.e., timing occasions at which the UE measures SSBs. If the i ; field is absent, the UE assumes that SSB periodicity is 5ms in this frequency. i i multiBandlnfoList i Indicates the list of frequency bands for which the NR cell reselection parameters apply. The UE shall select the first i I listed band which it supports in the multiBandlnfoList field to represent the NR neighbour carrier frequency. The i i network always includes this field._________________________________________________________________________________________i i multiBandlnfoListSUL i Indicates the list of frequency bands for which the NR cell reselection parameters apply. The UE shall select the first i i listed band which it supports in the multiBandlnfoListSUL field to represent the NR neighbour carrier frequency.________i i multiBandNsPmaxUstNR I Indicates the NS-PmaxListNR configuration for the NR frequency band(s) listed in multiBandlnfoList. The first entry ; corresponds to the second listed band in multiBandlnfoList, and second entry corresponds to the third listed band in ; ; multiBandlnfoList, and so on. i i muitiBandNsPmaxUsiNR-SUL I Indicates the NS-PmaxListNR configuration for the NR SUL frequency band(s) listed in multiBandlnfoListSUL. The i i first entry corresponds to the first listed band in multiBandlnfoListSUL, and second entry corresponds to the second i ; listed band in multiBand^^^ and so on. i i nr-FreqNeighHSDN-CellList [ List of neighbouring NR HSDN cells as specified in TS 38.304

[92] ._____________________________________________________________________________________________________________i ; ns-PmaxListNR i Indicates a list of additionalPmax and additionalSpectrumEmission, corresponds to the first listed band in the i I multiBandlnfoList. i i p-MaxNR [ Indicates the maxi^mumi ; q-QualMin i Parameter "Qquaimin" in TS 36.304 [4], applicable for NR neighbour cells. If the field is not present, the UE applies the i i (default) value of negative infinity for QqUaimin. The actual value Qquaimin = field value [dB].___________________________________i i q-RxLevMin i Parameter "Qrxievmin" in TS 38.304

[92] , applicable for NR neighbour cells. The actual value Qmievmin = field value * 2 i i [dBm].________________________________________ i i q-RxLevMinSUL i i Parameter "Qrxievmin" in TS 38.304

[92] , applicable for NR neighbouring cells. The actual value Qrxievmin = field value * 2 i i [dBm]. i i smtc2-LP i Measurement timing configuration for inter-RAT neighbour cells in NR with a Long Periodicity (LP) indicated by i i periodicity in smtc2-LP. The timing offset and duration are equal to the offset and duration indicated in i i measTimingConfig in CarrierFreqNR. The periodicity in smtc2-LP can only be set to a value strictly larger than the i i periodicity in measTimingConfig in CarrierFreqNR (e.g. if measTimingConfig indicates sf20 the Long Periodicity can i i only be set to sf40, sf80 or sf160, if measTimingConfig indicates sf160, smtc2-LP cannot be configured). The pci-List, i if present, includes the physical cell identities of the inter-RAT neighbour cells with Long Periodicity. If smtc2-LP is i i absent, the UE assumes that there are no inter-RAT neighbour cells with a Long Periodicity.___________________________i SystemlnformationBlockType24 field descriptions i ssb-PositionQCL-CommonNR ; Indicates the QCL relationship between SS / PBCH blocks for NR neighbor cells on the indicated frequency as i specified in TS 38.213

[88] , clause 4.1. If ssb-PositionQCL-CommonNR-r17 is present, the UE ignores ssb- ; PositionQCL-CommonNR-r16. i ssb-ToMeasure ; The set of SS blocks to be measured within the SMTC measurement duration (see TS 38.215

[89] ). When the field is i absent the UE measures on all SS-blocks. ; ss-RSSi-Measuremenis i Indicates the SSB-based RSSI measurement configuration. If the field is absent, the UE behaviour is defined in TS i 38.215

[89] , clause 5.1.3. i subcarrierSpacingSSB ; Indicates the subcarrier spacing of SSB of NR frequency. Only the values 15 kHz or 30 kHz (FR1), 120 kHz or 240 I kHz (FR2-1), 120 kHz or 480 kHz (FR2-2) are applicable. If subcarrierSpacingSSB-r17 is present, the UE ignores i subcarrierSpacingSSB-r15._______________________________________________________________________________________ i ihreshRS-lndex i List of thresholds for consolidation of L1 measurements per RS index. Corresponds to the parameter absThreshSS- i BlocksConsolidation in TS 38.304

[92] , i threshX High i Parameter "Threshx, wp" in TS 36.304 [4].____________________________________________________________________ i threshX HighQ i Parameter "Threshx, maha" in TS 36.304 [4].________________________________________________________________________ ; threshX-Low i Parameter "Threshx. lowp" in TS 36.304 [4], i ihreshX-LowQ i Parameter "Threshx lowq" in TS 36.304 [4], i t-ReselectionNR i Parameter "TreselectionNR" in TS 36.304 [4], I t ReselectionNR-SF i Parameter "Speed dependent ScalingFactor for TreselectionNR" in TS 36.304 [4], If the field is not present, the UE i behaviour is specified in TS 36.304 [4]._________________________________________________________________________________ Conditional presence Explanation i RSRQ i The field is mandatory present if the threshServingLowQ is present in i system In form ationBlockType3' otherwise it is not present. i RSRQ2 I The field is optional Need OP if the threshServingLowQ is present in i systemlnformationBlockType3' otherwise it is not present. i SharedSpectrum ; SharedSpectrum2 i The field is optional Need OP if NR operates with shared spectrum channel access; ; otherwise, it is not present._____________________________________________________________________________________________________________________________________ i The field is mandatory present if NR operates with shared spectrum channel access; [ otherwise, it is not present. 36.331 Release 17 V17.5.0, June 2023 Example #2 5 Specification changes are shown in bold. 36.331 Release 17 V17.5.0, June 2023 RRCConnectionRelease The RRCConnectionRelease message is used to command the release of an RRC connection, or to complete an UP-EDT procedure. Signalling radio bearer: SRB1 RLC-SAP: AM Logical channel: DCCH Direction: E-UTRAN to UE RRCConnectionRelease message — AFIIIFTART F.FC'FonnectionRelea : = ::= FErLEO-'E rrc-Trana acta . rR : = , nfi-r a ana act icnl'ientif lee, cniticalE::t=nci : na IHQICE { I O "‘ . ■ III'.* I >I. c - ra = ' • : ' - I . I - I F,. , -(-..11.=--: n:.::...:.., ..(:.,..:1.,.: ri 11.1., 1,, .-.-:. =: +.-:. =11,.1., criticalEina-CskiinFuture FEQFEIICE (J lBlB:i:::iilii:l:BlB:::iiii::BlllB:l:iiliil OOsnOsfilOSSISiOSsSSRiSss? ralaaaaCauae sssssnellSSsEsHSSrnleiiiwtSssg i~il=II i-II -1 tint ii"ii,li il 1 HF . .. 1 RR, a '"i nr - ■ I o aiR. I ■ - -,=-11,, 11+-=11 1 + 11+1--.- == : 1 1: IEs ' OPTIONAL, ciciCKisinOS^SiSaiiERBOst®^ f = ~ __=,_t = j'Hriicrliit'., >>ETIolI“L, 1:1=:.1 1=11,.1-,lilt L-Contr,..llnf; OETIOIIRL, Ri.. ' . I: cl 1 ul" 1 I.,- - • - -..- ol'TIoIFH, — Hee: Oil — Oa=: CO -1. FIRIHG o >*111=111- - -= . .nnuti.1:1 = 1=11—- = - FF T ?: c n = ct ionRele aa = ---?L i-IEc OPTIO1IAL — Late non critical ei-.renai'ina RRCOonnect ionRele ja a-’n eC-IEe ::= FERtlEHE : r-iii- t-o i_i_--l.f -=+-, F = i_--.1 = .--‘itii-ilnt --=-=1 FEI-IPL, — c nl 11 F-.--- = .r- l-.ll- H'„-l M-,bi .-., • 11,.11111,,-. ..... :-,. . 1=1 b 4 , i I i I ,11, 4 11 l - . : >- ......I'T b HILI,, i: 14'1 1 1 1 - H F = । n.o. "L I ) - -I Tb HI, I — Regular non oriel cal e.otenaiona RR-FConnectlonReleaae---; 1 u-IEa ::= FEO-IE.-?E CelllnfoLiat-r? CHOICE ( ceran-r: -FelllnfoLiatHERAil---?, utra-FEL-rl ?ellintoLiatUTRA-EII-c1, Utra-TCf-r? CelllnfoLiatUTRA-ILL-rS, ARC- ’ 1:1:=-11 i:R=l-a-=- 1 _o-IE. ::= FER E IE - r-ni-ibiltl- --11, I IL +IF ........... nonCritic alEnrer.r 1::1 F.F i 1: :.n=ctionRele a a = C-II I1PL, 11=-1 ' RRO?onnecti = nR=le 1.: = -=1:1 u-IEa : := .SEQI-iI.ILe ; 1 ■ 1 Hit' T11 111 i ' , — r C F - . • ■ TH' Ui 1 1 , - F V’ 0F-TT01 [F,T , — ” ' OF 1 = 010.11- i 1 iciih r: • n.-i :-0 :-1--0=:1:+:.01:)0110, 0 1.:,:.--.-:. + .=.--:0,: Ol'Tl OIL 1, RF> >nn-_ti nF=l-- — _ -IE ::= I E dll-<' iitiuu=' - -.A EETarPUR n=._tH. yi'lnini .- _A _ r.t-rl E SavlyRec meaaldleConfi q-rl; cn-Type-rl5 nC'nCL'itia alEaraaai.: n I-:1,'1 0-1111 ci 1 >a !■:•.:■ J.c ::.::-----.-111 i-j.E.i W.' i I "I" i 11 = 1 mlit’r i I i_- j 1E::-. ■_• .-.ci ::i =R ''' nn=_ti nR=l--.-- '_E1-1 -IE. liiSSiBsBSSaSsisSBEOOOiOiiSSSSii L‘ AOLATEL- {true} : r Lend Oii ? lent ~ -? p C h a i ri i n g C o u n t < E'TIQIIAL, -- Oor. 1! F PT 101 LAL, llllBli OPTIOPAL, -- OPTIOHAL, -- -) i1 i iF1-i —t _ - ^iOPTlOPj - ■ K 11..1..: y.j , — o ,f,: | ,,:1 .-.-1 ' n । Ll'.nK-l- K - _ I'lTlnlL.L EEA.EEATEL [true} -1111-1 HAL, — H = =d -IE ay n=_ti nR=l = a.-=-• I I -EE oETIolPL -F'V;un^tl.l:AR.-.a- _ ali'-IE: t il I J. I -RI IT1-111 1 .-1::-:1-1- T-Rl IT I -ri .. [,'U 1.--:.1. Ui II I '.i-i:: r a--Tn *b.*.-1 1:= —-,'l E. 1 ” IRLEaERR alt FrAqPri = riti=a-rlfi ®§8egsSsgag8UAH®ioa: EEgUEH Rl.TT-ll ■] 'T 1 ol | 1,, — ll'l.' 1. 0:- El A A- 7 OOiOAS ■ ’ V 1 t. { PLIJI-'EaIiL 0 Oi'.' u 01.-0,, — He ■■ :-: A" { optional :1 OIL ., . .... Agl > • P.O I i-f i r i g-v 1 i- i OPTlOlAL, - : Epp 0 AAATED {true} OPT 101 LAL, -- lie-: 00 {true} ’PET 101 LAL, — Lfeej AH' iiioygiiipp OTOTEO _\T, nurilL iiiiiiiiii , hll_ / i i |||ll|||i '0 _ "ne jti yriReleyue-'A "PTIOIIAL, 11==.' -s -Ai-EEa OPTIOHAL h' 1IMCTATKR (I fui--} i.-TA-lliL, — -AiA Ri-.-• lyHIl'Tl I } '.> .A..'.--" EHUI IE R AT E L- - 1 -.:- ad E a 1 a n c i nq T AU r a : :d r A, RedirectedCarric-E.-;f.? :: eutra q---ran ill । , p1H V j n I. rn-TUIa giiiiiiiiggSggggggHggBiK =dni a......-1:.1:. 1 utra-TDR-rll nr-rl IS RRy-y-yali AEUTRA, 'a - - . aFi cqa'lER-lI, ' Ia-'I -1 >1:1 UTI I, ARF-T 1-=11 i.iAJTHA, < . i I r qdHI / ......., 1 a t.-aarFraqLic tUTRA-TE S-_~11, CaciierlnfcHR-rlS, EiLLiarlrifi'lIR-rlT ge® AREORUalHgEUTRAgd Al 11 = 1 F1 = qLi. tt .7,— ,._-ili ::= Ta. _.- "E (File <1. . in a . a a- . a-ti r-i 1> i >><>F .- -- a Idlellqdellqbilit y I: =t it llnf.:- ::= EEyCEASE - fr=qPri=rityLiatEUTRA Fi=qi-ii = rityLietEUTRA -OPTIOHAL, — - Oil frdqprii'i’it yEiat PEE AH FiaiaFnarityLiatgERAl' EE'TIillAL, — la-: 011 fi-=qpi’i _ ntyL_a tUTEA-FRE1 Fan.1 ci :-11 tyLia tUTRA-a EE OETIt>IIA.L, -- An; oil fr=qPri'_'rityLiatUTEA-TEE> Fc-aqE 11 = 1 ItyListUTRA-TEE OPTIOHAL, — Aa OH b m-l'A i. . Prl >. HIPPE- ~ I. -a 1 ,. . p i I - -1 1 I yT, 1. -1 I A' ~ -OPTTOHE-L, --^---011 I m 1' ‘I i.- 1-11.:.--,-...11 I IT .-, .- ..i-.lii I i I , l,i A . ,:A1 -I T 1 All I,, -- HI I* ’ u Fl 1 *’ ;F AATE I’1 [ aAiIS , in 1 111 11, m 1 11 ’i*-, a. A. .-:, mi n O', in I 111 T>, -.11.1 , CL.atAl} OETlOllAL, — 11 = =1 Oh [[ fiAqpri'AAAyLiatE:.tEUTRA-tl_ FcHqPri = rityLiatE:HEUTEA-rli OPTIOHAL - Era A [ [ froqpL-ii-—yli..= rEUTRA---151N ijijijijijigggoggEgigisgigo ^|i|l|i|i|l|IM [ [ fL’eqPriiLlc'yllarNR-L’15 ] ] , [[ freqPriorityListNR-MobileIAB-rl8 — Need ON ] ] jRreggsSg:CllgEl:3g®0®:Os®131®iKSB7SSHffiEgi?i?i®s5?HeediKSfl: FeeqPriorityLietE::cETTRA-- / l Hu OPTIONAL — Need FLei;iprll;,rityLi3tlIF-Ll: OPTIONAL — .le: ON FreqPriorityListNR-MoblleIAB-rl8 OPTIONAL . . . ILTM . . . FreqPriNL-ityLia t ggOgENgg SEQUENCE { AREH-ValueNR-i-15, _'ity-rl !• Cel IRee el eel loi-iP'raeL'iey, cellReeelectiaa eeiiReeeiecti;;-: OPTIONAL — 1~: Op FreqPriorityNR-MoblleIAB-rl8 ::= carrierFreq-rlS celiReselectionPriori ty-r15 cellReselectionSubPriority-rlS ?aL-rieL-InfoNR-i:l~ : := SEQUENCE c a rr i e r Ere q-L 1 aparel}, emtc-rll SEQUENCE { ARFCN-ValueNR-rl5, CellReselectionPriority, CellReselectionSubPriority-rl3 OPTIONAL — Need OR . . . TUTTED . . . . ml ’--ri 1 -m -NK-i 1 L NH::1 •’", 11-1:110 1, iiiiiiBTTONSEiiiiliggi ARFCN- 1:1. eHR-rld, ENHESATED [LHcll, 1:11, cEcllO, 11140, LHc-H 4, 141 4-SSE-NR-rH ..PHONAL — Nee? Ol- ______________________________RRCConnectionRelease field descriptions____________________________ ......................................................................................................... . 7 d / W / 7TEb7 ...................................................................................................... freqPrioriiyList^ Indicates a set of frequencies for mlAB cell reselection, see TS 36.304. If present, the freqPriorityListNR may also be present. ........................... Example #3 Specification changes are shown in bold. 38.331 Release 17 V17.5.0, June 2023 RRCRelease Message The RRCRelease message is used to command the release of an RRC connection or the suspension of the RRC connection. Signalling radio bearer: SRB1 RLC-SAP: AM Logical channel: DCCH Direction: Network to UE RRCRelease message ixlvikele ace : : ■■ rrc-Tranc act! : clcleictif ier critic alErteusi: rc rrcRelende critic a!E:c Aciorc Future RRi'R=l = .as = -IEs ::= 1 ' -i i I - I • -,|i' I: : - : T:' J. 1 11-=-1-: J. t 11 T ' •.' I I. T: I- Ti.y- il-:IC' n 1’ i .: d -1 I - I i I i ,: I ■ At • depiiorilissiiTiTyps rtststsOpKlSLlAESaiid^^^ 99999^ ~ r. ?-Fr ana a = ti-;-riId = nti 1 i, RECA'IE ( RA'ER=1 = as-a-IEs, 3EQUE1RTE ( } E. RIIERATEL (nan", _ 1 , lullil", mln,"} OTTIOHAL, — Ar: A :atet steiia optiaial, : i AIT i mr liisiiisisiOisSOSiMSdOA^ cE}"L Em A .'Au I T i lu= i:i:i:tSisO©ReiUiaiO:S^ ATTulER, -- II-< ’ITT AF-I nR 'R=l=a. =- 1ml = : : = TisisisisiOiS'OiWOifeasUfiSs:^ ni= as 1-11=11-11 fi a-sl: — Heed II diiisisisiOAOiUAAAAnsaAUsisis EEQliEUE ■: EAAiEPATEL {true} OPTIOHAL, -- Hees 1 EelipRelease (I feaald leC=:if l-A-edieat ed-i'l<;.} Or aRAHAL, AAI'AsLsaie-vlim-IEi OPTIOHAL F1 IaI'A. --— 1 r r| —__ : := EEQFEXIE ( inf , Pri j ri t vT , 1" 1 =11-1-1= - ."RATER- [tin"} oRTTolP.L, -- "= - :r- H i r ।: I i ■ a i.' ij'CjFr i । i c । J.h .r: - rci :-11 r ACAa.==>:,: <-■ A -1 =-J E.। ORT loHXl, IliiiiiiiigAlggAiEAAAS 1E1 E IE EAR:ERATED (true} EIEQHEARE (} nlTAIIAL, — ' ear I OITIOIIAL CHEA ?E = si_AelIrif=l[R, e-~l_ ==i = 1 'arii-iliif - - -E’ R=-ii r< -'ll nd-'I'i it i • ■ = = ; -A>TR / - ::-= ul ruFiequer;-:r A-iIyp-e AR Fl I-I - A a 1 u = E U T RA, E .'E-ATEE (=1-,11==:1- I'lTInlAL OaLriaLlrif cIIR : : = carriarFraq chit C EQTENOE AF FA'-AslUtllR, s ?_'LierFpaciriq, OFTIO1JAL, Ou..- paudbauflq :: JU; UU. { tul J. 1-EI IT 1 .-:0-11 1 -PUTT r jh-Lj uiupOyj--. ran-Natif ic st 1z n-.raslnfa :-1:0 .:-: ii iu , :-piiTi । i|f.r : iilnpONi-p., A-N-Na-t i f i a Rt ianAra alnza ilBiillllo oooBIB na::t Hapohamanz Paul z ziaRlIAJJ-TimarlbdlL a . ana - :plbsiningCaunt, OPTIONAL, -- : a a ? £ 1-UEIdant ityF a. :^-ir RNTI-”alua OPTIONAL, — At LlEenn'tebE sdt-Oanfiq-rl" SerLcRelea^ { FDT-0-_Tfiq-rl" } OPTIONAL, — Need IT 1 j -1 t jF R1 1'. •:' . - i 1 <t :- • J b f { PRJ--F> bO- : .t11 i -■ - *q ] - ) option / l, -- lOr^i :: : i u I-E I ' 1 P P T . ).'. t ' , a b - -i 1 1 T T b *1 L’ I, RAN:PagihgLLLLLLLLi:<OLTLLLLLLLLLLLLLLLLL ncd-FFE-R^di b:__ blEWE-3L T-rl" ? = z _ c a al - =1.= a [ I lonO^l 11 ad____^FFE-rl^} OFTIORAL — Head A ||||ll|||||||||||||||||||||||||||||||||| 'O-’l IRt-t'O-.t b-ri pt 1 ;• b 0--,.-1 ::-■-■ REb' / EI AT i 1 t q I t 11 । r t I a "' TA L ’ 1 - -1 i I ("L i >11 U ITE I "’IAIN,, -- . •' - ' ’ fraqFridlsityLi<-t;’R FaaqPricrityLiPtNH. OPTIONAL, — Raai 0 t__'' E .’E^ATEE' [mini, mini , i _A(, iiiin'-'y nmp m, _ L_ >, minH'b .spiral} OPTIONAL, — ITaad F- illliBBBIlIlIlIliilBlllllllllllllllllllllllllB OPTIONAL — Raad 0 lllliiitlliilllllllpssiblllllllllllEIlllllliN SreqPriorityListNR-rlB FreqPriorityListNR-MobilelAB OPTIONAL, — Need M i j jagingCycla ::= ENKrER.A_r_„ {rfll, rfE4, rfl_:, rzllE} O A AddddO d EIJLT'ARATEL {rflLL, rfLll, rfll-LT, yaial} FraqPriai'ityLic tEOIF-A :: = FEC-ad-E FILE (1. .ultFi-t,. OF FrayPriorityEUTRA FieciFriarityLiatNF :: = FEqOEOPE FILE 11. .mTzFiiaq - PF FiaqFri'irityNR FreqPriorityListNR-MobilelAB ::= SEQUENCE (SIZE (1..maxFreq)) OF FreqPriorityNR-MobilelAB •■’v'- q Obi.'.ir 1 I.', EUTRA : : •• a") IT i ' l'l;,T q “'-llR-z '-I'- _ity _-llF-1-0 on iiR T. V.-T.-TT; | IjrEHTR , OallRasalact ianPriariz y, PallRasalaationFubPrieazzy OFTIOILAL -- Taa? R FragPriarityNR ::= tarriarFraq callRacalaatiinPai—ity zrllR-z-1-. AiAi.nt, |ii|||||g|||||||||||||||||^^^^^ AEFOO-V^luallR, PallRasal act ianEriai'iT y, ?allRa3alactianFubFrici.'izy OPTIONAL -- Naaz R FreqPriorityNR-MdbilelAB ::= carrierFreq celIReselectionPriori ty cellReselectionSubPriority mobilelAB-Assistancelnformation SEQUENCE { ARFCN-ValueNR, CcllResclcctionPriority, CellReselectionSubPriority OPTIONAL, MobilelAB-Assistancelnformation — Need R . . . OCTTED • • • 5 ______________________________________RRCRelease-IEs field descriptions______________________________________ cellReselectionPriorities Dedicated priorities to be used for cell reselection as specified in TS 38.304

[20] , The maximum number of NR carrier frequencies that the network can configure through FreqPriorityListNR and FreqPriorityListDedicatedSlicing together is eight. If the same frequency is configured in both FreqPriorityListNR and FreqPriorityListDedicatedSlicing, the frequency is only counted once.______________________________________________________________________________________________________ cnType Indicate that the UE is redirected to EPC or 5GC.__________________________________________________________________________ deprioritisationReq Indicates whether the current frequency or RAT is to be de-prioritised.______________________________________________________ deprioritisationTimer Indicates the period for which either the current carrier frequency or NR is deprioritised. Value minN corresponds to N minutes._________________________________________________________________________________________________________________ measIdleConfig Indicates measurement configuration to be stored and used by the UE while in RRC IDLE or RRC INACTIVE._____________ mpsPrioritylndication Indicates the UE can set the establishment cause to mps-PriorityAccess for a new connection following a redirect to NR. If the target RAT is E-UTRA, see TS 36.331

[10] , The gNB sets the indication only for UEs authorized to receive MPS treatment as indicated by ARP and / or QoS characteristics at the gNB, and it is applicable only for this instance of release with redirection to carrier / RAT included in the redirectedCamerlnfo field in the RRCRelease message._______________________ noLastCellUpdate Presence of the field indicates that the last used cell for PEI shall not be updated. When the field is absent, the PEI-capable UE shall update its last used cell with the current cell. The UE shall not update its last used cell with the current cell if the AS security is not activated._______________________________________________________________________________________________________________ srs-PosRRC-lnactiveConfig SRS for positioning configuration during RRC INACTIVE state._________________________________________________________ suspendConfig Indicates configuration for the RRC_INACTIVE state. The network does not configure suspendConfig when the network redirect the UE to an inter-RAT carrier frequency or if the UE is configured with a DAPS bearer._____________________________ redirectedCamerlnfo Indicates a carrier frequency (downlink for FDD) and is used to redirect the UE to an NR or an inter-RAT carrier frequency, by means of cell selection at transition to RRCJDLE or RRC_INACTIVE as specified in TS 38.304

[20] , Based on UE capability, the network may include redirectedCamerlnfo in RRCRelease message with suspendConfig if this message is sent in response to an RRCResumeRequest or an RRCResumeRequestl which is triggered by the NAS layer (see 5.3.1.4 in TS 24.501 [23().________________________ voiceFallbacklndication Indicates the RRC release is triggered by EPS fallback for IMS voice as specified in TS 23.502

[43] , 10 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 15 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. For example, in the following examples, a network may include one or more IAB nodes. 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, claim, example and / or embodiment disclosed herein. Certain embodiments of the present disclosure provide a machine-readable storage storing such a program. The same or similar components may be designated by the same or similar reference numerals, although they may be illustrated in different drawings. Detailed descriptions of techniques, structures, 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. 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 examples disclosed herein. Throughout the description and claims, the words “comprise”, “contain” and “include”, and variations thereof, for example “comprising”, “containing” and “including”, means “including but not limited to”, and is not intended to (and does not) exclude other features, elements, components, integers, steps, processes, functions, characteristics, and the like. Throughout the description and claims, the singular form, for example “a”, “an” and “the”, encompasses the plural unless the context otherwise requires. For example, reference to “an object” includes reference to one or more of such objects. Throughout the description and claims, language in the general form of “X for Y” (where Y is some action, process, function, activity or step and X is some means for carrying out that action, process, function, activity or step) encompasses means X adapted, configured or arranged specifically, but not necessarily exclusively, to do Y. Features, elements, components, integers, steps, processes, functions, characteristics, and the like, described in conjunction with a particular aspect, embodiment, example or claim are to be understood to be applicable to any other aspect, embodiment, example or claim disclosed herein unless incompatible therewith. While the invention has been shown and described with reference to certain examples, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the invention, as defined by the appended claims. Abbreviations / Definitions n the present disclosure, the following abbreviations and definitions may be used. 3GPP 5G cpp obL AMF CU DC DL DU EN eNB en-gNB EPC E-UTRA E-UTRAN 3rd Generation Partnership Project 5th Generation 5G Core Access and Mobility Management Function Centralised Unit Dual Connectivity Downlink Distributed Unit Enterprise Network E-UTRAN NodeB Enterprise Network 5G base station Evolved Packet Core Evolved Universal Terrestrial Radio Access Evolved Universal Telecommunications System Terrestrial Radio Access Network gNB IAB ID IE LTE mlAB N4 NG NGC NR PDCP QoS RACH RAN RAT Rei RRC SDAP SIB TR TS UE UL UTRAN Uu X2 Xn 5G base station Integrated Access and Backhaul Identity / ldentifi cation Information Element Long Term Evolution Mobile Integrated Access and Backhaul Interface between Control Plane and User Plane Interface between 5G RAN and Core Control part of NG New Radio Packet Data Conversion Protocol Quality of Service Resources Access Channel Radio Access Network Radio Access Technology Release Radio Resource Control Service Data Adaption Protocol System Information Block Technical Report Technical Specification User Equipment UpLink Universal Telecommunications System Terrestrial Radio Access Network Air interface between terminal and base station / access point interface between 2 base stations interface between n base stations

Claims

1. A method of performing inter-RAT mlAB mobility by a UE of a communications network, the method comprising:receiving inter-RAT mlAB assistance information from a node of the network comprising information on the presence of one or more mlAB cells on one or more cell frequencies;prioritizing a cell frequency with one or more mlAB cells present, andperforming reselection of a mlAB cell from the one or more mlAB cells on the prioritised cell frequency.

2. A method according to claim 1 further comprising the UE camping on the reselected mlAB cell.

3. A method according to claim 1 or claim 2 in which, in the received mlAB assistance information, the information on the presence of one or more mlAB cells on one or more cell frequencies comprises a flag indicating that there are one or more mlAB cells on the or each cell frequency.

4. A method according to any preceding claim in which the mlAB assistance information comprises a list of the one or more mlAB cells on the one or more cell frequencies.

5. A method according to any preceding claim in which the mlAB assistance information is received per cell frequency.

6. A method according to any preceding claim in which the mlAB assistance information comprises information on a mlAB-specific timer which sets a time in which the UE is to perform inter-RAT mlAB mobility by reselection of a mlAB cell.

7. A method according to claim 6 in which the mlAB assistance information is received for all mlAB cell reselection parameters.

8. A method according to any preceding claim in which the mlAB assistance information is received in a System Information Block (SIB).

9. A method according to claim 8 in which the SIB is SystemlnformationBlockType24.

10. A method according to any of claims 1 to 7 in which the mlAB assistance information is received in a release message.

11. A method according to claim 10 in which the release message is a RRCRelease 5 message.

12. A method according to any preceding claim in which, when the UE is released to any of RRC idle mode, RRC inactive mode, the mlAB assistance information is received by the UE.1013. A method according to any preceding claim in which the UE of the network receives the inter-RAT mlAB assistance information from a E-UTRAN node of the network and the UE performs reselection of a NR mlAB cell from the one or more mlAB cells on the prioritised cell frequency.1514. A method of a node of a communications network comprising signalling mlAB assistance information to a UE of the network for the UE to perform a method of inter-RAT mlAB mobility according to any of claims 1 to 13.

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