Method and apparatus for mobile IAB inter rat mobility and intra rat mobility

Abstract

The disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. A method is provided of performing inter-RAT mIAB mobility by a UE of a communications network, the method comprising obtaining, from a BS, a SIB including information related to an inter RAT cell, wherein the information related to the inter RAT cell includes at least one or: information on frequencies with one or more mobile IAB cells or information on a list of one or more mobile IAB cells; and in case that a inter RAT mobile IAB cell is detected, considering a inter RAT frequency for the inter RAT mobile IAB cell to be the highest priority for cell reselection.

Description

METHOD AND APPARATUS FOR MOBILE IAB INTER RAT MOBILITY AND INTRA RAT MOBILITY

[0001] An embodiment of the present disclosure provide various techniques relating to methods for mobile integrated access and backhaul (mIAB) inter and intra radio access technology (RAT) mobility, for example methods for signalling mIAB idle mode / inactive mode inter-RAT and intra-RAT mIAB assistance information, for example within 3rd Generation Partnership Project (3GPP) 5th Generation (5G) New Radio (NR) and NR-based relay networks.

[0002] 5G mobile communication technologies define broad frequency bands such that high transmission rates and new services are possible, and can be implemented not only in "Sub 6GHz" bands such as 3.5GHz, but also in "Above 6GHz" bands referred to as mmWave including 28GHz and 39GHz. In addition, it has been considered to implement 6G mobile communication technologies (referred to as Beyond 5G systems) in terahertz bands (for example, 95GHz to 3THz bands) in order to accomplish transmission rates fifty times faster than 5G mobile communication technologies and ultra-low latencies one-tenth of 5G mobile communication technologies.

[0003] At the beginning of the development of 5G mobile communication technologies, in order to support services and to satisfy performance requirements in connection with enhanced Mobile BroadBand (eMBB), Ultra Reliable Low Latency Communications (URLLC), and massive Machine-Type Communications (mMTC), there has been ongoing standardization regarding beamforming and massive MIMO for mitigating radio-wave path loss and increasing radio-wave transmission distances in mmWave, supporting numerologies (for example, operating multiple subcarrier spacings) for efficiently utilizing mmWave resources and dynamic operation of slot formats, initial access technologies for supporting multi-beam transmission and broadbands, definition and operation of BWP (BandWidth Part), new channel coding methods such as a LDPC (Low Density Parity Check) code for large amount of data transmission and a polar code for highly reliable transmission of control information, L2 pre-processing, and network slicing for providing a dedicated network specialized to a specific service.

[0004] Currently, there are ongoing discussions regarding improvement and performance enhancement of initial 5G mobile communication technologies in view of services to be supported by 5G mobile communication technologies, and there has been physical layer standardization regarding technologies such as V2X (Vehicle-to-everything) for aiding driving determination by autonomous vehicles based on information regarding positions and states of vehicles transmitted by the vehicles and for enhancing user convenience, NR-U (New Radio Unlicensed) aimed at system operations conforming to various regulation-related requirements in unlicensed bands, NR UE Power Saving, Non-Terrestrial Network (NTN) which is UE-satellite direct communication for providing coverage in an area in which communication with terrestrial networks is unavailable, and positioning.

[0005] Moreover, there has been ongoing standardization in air interface architecture / protocol regarding technologies such as Industrial Internet of Things (IIoT) for supporting new services through interworking and convergence with other industries, IAB (Integrated Access and Backhaul) for providing a node for network service area expansion by supporting a wireless backhaul link and an access link in an integrated manner, mobility enhancement including conditional handover and DAPS (Dual Active Protocol Stack) handover, and two-step random access for simplifying random access procedures (2-step RACH for NR). There also has been ongoing standardization in system architecture / service regarding a 5G baseline architecture (for example, service based architecture or service based interface) for combining Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and Mobile Edge Computing (MEC) for receiving services based on UE positions.

[0006] As 5G mobile communication systems are commercialized, connected devices that have been exponentially increasing will be connected to communication networks, and it is accordingly expected that enhanced functions and performances of 5G mobile communication systems and integrated operations of connected devices will be necessary. To this end, new research is scheduled in connection with eXtended Reality (XR) for efficiently supporting AR (Augmented Reality), VR (Virtual Reality), MR (Mixed Reality) and the like, 5G performance improvement and complexity reduction by utilizing Artificial Intelligence (AI) and Machine Learning (ML), AI service support, metaverse service support, and drone communication.

[0007] Furthermore, such development of 5G mobile communication systems will serve as a basis for developing not only new waveforms for providing coverage in terahertz bands of 6G mobile communication technologies, multi-antenna transmission technologies such as Full Dimensional MIMO (FD-MIMO), array antennas and large-scale antennas, metamaterial-based lenses and antennas for improving coverage of terahertz band signals, high-dimensional space multiplexing technology using OAM (Orbital Angular Momentum), and RIS (Reconfigurable Intelligent Surface), but also full-duplex technology for increasing frequency efficiency of 6G mobile communication technologies and improving system networks, AI-based communication technology for implementing system optimization by utilizing satellites and AI (Artificial Intelligence) from the design stage and internalizing end-to-end AI support functions, and next-generation distributed computing technology for implementing services at levels of complexity exceeding the limit of UE operation capability by utilizing ultra-high-performance communication and computing resources.

[0008] It is an aim of an embodiment 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 an embodiment of the present disclosure to provide at least one advantage over the related art, for example at least one of the advantages described herein.

[0009] Other aspects, advantages, and salient features of the present disclosure will become apparent to those skilled in the art from the following detailed description taken in conjunction with the accompanying drawings.

[0010] In one aspect of the present disclosure there is provided, in a communications network, a method of the network signalling inter-RAT mIAB assistance information or intra-RAT mIAB assistance information to a UE of the network for mIAB inter-RAT mobility or intra-RAT mobility.

[0011] The method may comprise the UE being configured with intra-RAT mIAB cell assistance information in a NR mIAB 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 mIAB cell assistance information in an E-UTRA cell when the UE is released to RRC idle mode or RRC inactive mode.

[0012] In one aspect of the present disclosure there is provided a communications network which signals inter-RAT mIAB assistance information or intra-RAT mIAB assistance information to a UE of the network for mIAB inter-RAT mobility or mIAB intra-RAT mobility.

[0013] Figure 1 illustrates a two-hop IAB network, taken from TR 38.874 "Study on Integrated Access and Backhaul", V16.0.0, December 2018,

[0014] Figure 2 illustrates a mobility from NR to E-UTRAN procedure,

[0015] Figure 3 illustrates connected mode mobility,

[0016] Figure 4 illustrates a RRC release procedure,

[0017] Figure 5 illustrates RRC Connection Release procedures,

[0018] Figure 6 illustrates a deployment scenario with macro cells and mIAB cells on a train travelling in a limited area of the macro cell deployment,

[0019] Figure 7 illustrates eNB signalling inter-RAT mIAB cell assistance information,

[0020] Figure 8 illustrates indicating mIAB cell presence and then gNB choosing to broadcast mIAB cell assistance information,

[0021] Figure 9A illustrates releasing a UE and configuring it with mIAB inter-RAT prioritization information or mIAB cell assistance information for intra-RAT and inter-RAT cases,

[0022] Figure 9B illustrates releasing a UE and configuring it with mIAB inter-RAT prioritization information or mIAB cell assistance information for intra-RAT and inter-RAT cases,

[0023] Figure 10 illustrates an example of how to configure a UE with mIAB prioritization information or mIAB cell assistance information,

[0024] Figure 11 illustrates an example of how to configure a UE with mIAB prioritization information or mIAB cell assistance information.

[0025] Figure 12 illustrates a flow chart of a method for mobile IAB inter RAT mobility in accordance with an embodiment of the present disclosure.

[0026] Figure 13 illustrates a flow chart of a method for mobile IAB inter RAT mobility in accordance with an embodiment of the present disclosure.

[0027] Figure 14 illustrates a block diagram of a user equipment (UE) in accordance with an embodiment of the present disclosure.

[0028] Figure 15 illustrates a block diagram of a base station (BS) in accordance with an embodiment of the present disclosure.

[0029] In one embodiment, a method of a UE (user equipment) in a wireless communication system is provided. The method comprises obtaining, from a BS(base station), a SIB(system information block) including information related to an inter RAT(radio access technology) cell, wherein the information related to the inter RAT cell includes at least one of: information on frequencies with one or more mobile IAB(Integrated Access and Backhaul) cells or information on a list of one or more mobile IAB cells; and in case that a inter RAT mobile IAB cell is detected, considering a inter RAT frequency for the inter RAT mobile IAB cell to be the highest priority for cell reselection.

[0030] In one embodiment, the information on the frequencies with one or more mobile IAB cells indicates that the one or more mobile IAB cells are deployed on the inter RAT frequency.

[0031] In one embodiment, the SIB is a SIB Type 24.

[0032] In one embodiment, the method further comprises obtaining a SIB 1 including information indicating a inter RAT cell is a mobile IAB cell; and identifying the inter RAT mobile-IAB cell, based on the information included in the SIB 1.

[0033] In one embodiment, the BS is an E-UTRAN(Evolved-Universal Terrestrial Radio Access Network) cell, the inter RAT mobile IAB cell is an NR(new radio) mobile IAB cell, and the inter RAT frequency is an NR frequency.

[0034] In one embodiment, the method further comprises receiving, from the BS, a radio resource control (RRC) release message including inter RAT mobile IAB cell assistance information; and based on the inter RAT mobile IAB cell assistance information included in the RRC release message, redirecting to the inter RAT mobile IAB cell.

[0035] In one embodiment, a method of a BS(base station) in a wireless communication system is provided. The method comprises broadcasting a SIB(system information block) including information related to an inter RAT(radio access technology) cell, wherein the information related to the inter RAT cell includes at least one of: information on frequencies with one or more mosbile IAB(Integrated Access and Backhaul) cells or information on a list of one or more mobile IAB cells; and wherein in case that a inter RAT mobile IAB cell is detected, a inter RAT frequency for the inter RAT mobile IAB cell is considered to be the highest priority for cell reselection.

[0036] In one embodiment, a UE (user equipment) in a wireless communication system is provided. The UE comprises memory storing one or more instructions; and at least one processor. The at least one processor is configured to execute the one or more instructions to: obtain, from a BS(base station), a SIB(system information block) including information related to an inter RAT(radio access technology) cell, wherein the information related to the inter RAT cell includes at least one of: information on frequencies with one or more mobile IAB(Integrated Access and Backhaul) cells or information on a list of one or more mobile IAB cells; and in case that a inter RAT mobile IAB cell is detected, consider a inter RAT frequency for the inter RAT mobile IAB cell to be the highest priority for cell reselection.

[0037] In one embodiment, the information on the frequencies with one or more mobile IAB cells indicates that the one or more mobile IAB cells are deployed on the inter RAT frequency.

[0038] In one embodiment, the SIB is a SIB Type 24.

[0039] In one embodiment, the at least one processor is further configured to execute the one or more instructions to: obtain a SIB 1 including information indicating a inter RAT cell is a mobile IAB cell; and identify the inter RAT mobile-IAB cell, based on the information included in the SIB 1.

[0040] In one embodiment, the BS is an E-UTRAN(Evolved-Universal Terrestrial Radio Access Network) cell, the inter RAT mobile IAB cell is an NR(new radio) mobile IAB cell, and the inter RAT frequency is an NR frequency.

[0041] In one embodiment, the at least one processor is further configured to execute the one or more instructions to: receiving, from the BS, a radio resource control (RRC) release message including inter RAT mobile IAB cell assistance information; and based on the inter RAT mobile IAB cell assistance information included in the RRC release message, redirecting to the inter RAT mobile IAB cell.

[0042] In one embodiment, a BS(base station) in a wireless communication system is provided. The BS comprises memory storing one or more instructions; and at least one processor. The at least one processor is configured to execute the one or more instructions to: broadcast a SIB(system information block) including information related to an inter RAT(radio access technology) cell, wherein the information related to the inter RAT cell includes at least one of: information on frequencies with one or more mobile IAB(Integrated Access and Backhaul) cells or information on a list of one or more mobile IAB cells, and wherein in case that a inter RAT mobile IAB cell is detected, a inter RAT frequency for the inter RAT mobile IAB cell is considered to be the highest priority for cell reselection.

[0043] In one embodiment, the information on the frequencies with one or more mobile IAB cells indicates that the one or more mobile IAB cells are deployed on the inter RAT frequency.

[0044] 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 disclosure, 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.

[0045] 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.

[0046] 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.

[0047] The skilled person will appreciate that the present disclosure is not limited to the specific examples disclosed herein. For example:

[0048] ● The techniques disclosed herein are not limited to 3GPP 5G.

[0049] ● 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.

[0050] ● 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.

[0051] ● One or more further elements, entities and / or messages may be added to the examples disclosed herein.

[0052] ● One or more non-essential elements, entities and / or messages may be omitted in certain examples.

[0053] ● 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.

[0054] ● 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.

[0055] ● Information carried by a particular message in one example may be carried by two or more separate messages in an alternative example.

[0056] ● Information carried by two or more separate messages in one example may be carried by a single message in an alternative example.

[0057] ● The order in which operations are performed may be modified, if possible, in alternative examples.

[0058] ● 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.

[0059] To satisfy extremely high data rate requirements, the 3GPP 5G NR standard utilizes communication frequencies in a relatively high range, from 30 GHz to 300 GHz, corresponding to wavelengths in the millimeter (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.

[0060] An embodiment 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.

[0061] An embodiment 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.

[0062] An embodiment of the present disclosure provide a computer or processor-readable data carrier having stored thereon a computer program according to the preceding examples.

[0063] The disclosure relates to additional methods for signalling mIAB idle mode / inactive mode inter-RAT mIAB assistance information or intra-RAT mIAB assistance information.

[0064] In the description below, the example embodiments may apply to eNBs, gNBs, en-gNBs, NG-RANs or NG-eNBs. For instance, in an embodiment, 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 an embodiment, there may also be methods explicitly for an NG-eNB, en-gNB, gNB, or NG-RAN.

[0065] Integrated Access and Backhaul (IAB)

[0066] 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.

[0067] 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.

[0068] Mobile IAB

[0069] 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 IAB-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]:

[0070] ● Define procedures for migration / topology adaptation to enable IAB-node mobility, including inter-donor migration of the entire mobile IAB-node (full migration). [RAN3, RAN2].

[0071] ○ the mobile IAB-node can connect to a stationary (intermediate) IAB-node, optimizations specific to the scenarios where the mobile IAB-node connects to a stationary (intermediate) IAB-node, or where it directly connects to an IAB-donor-DU are de-prioritized,

[0072] ○ the mobility of dual-connected IAB-nodes is down-prioritized.

[0073] ● Enhancements for mobility of an IAB-node together with its served User Equipments (UEs), including aspects related to group mobility. No optimizations for the targeting of surrounding UEs. [RAN3, RAN2].

[0074] ● Mitigation of interference due to IAB-node mobility, including the avoidance of potential reference and control signal collisions (e.g. PCI, Resources Access Channel (RACH)). [RAN3, RAN2].

[0075] Long Term Evolution (LTE) Inter-RAT Mobility

[0076] Connected Mode

[0077] 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.

[0078] 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).

[0079] Idle Mode

[0080] 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.

[0081] 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.

[0082] 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.

[0083] In NR, if a UE selects an inter-RAT cell while in RRC_INACTIVE, the UE transitions from RRC_INACTIVE to RRC_IDLE.

[0084] 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.

[0085] In idle mode for inter-RAT mobility there is the following system information broadcasted:

[0086] ● 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:

[0087] ○ carrier frequency lists of E-UTRA frequencies and E-UTRA cells;

[0088] ○ T-ReselectionEUTRA;

[0089] ○ cell reselection parameters such as priorities, selection thresholds, etc., and

[0090] ○ cell lists,

[0091] ● 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:

[0092] ○ carrier frequency lists of NR frequencies;

[0093] ○ cell reselection parameters such as priorities, selection thresholds, etc.;

[0094] ○ 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;

[0095] ■ the timer values are 0, 1, 2, ..., 7 seconds,

[0096] ○ NR-specific parameters needed to detect and measure NR cells:

[0097] ■ SMTC;

[0098] ■ SSB information such as SSB SCS, SSB position, SSB Measurement Timing Configuration (SMTC),

[0099] ○ cell lists.

[0100] RRC Release

[0101] NR RRC Release

[0102] 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.

[0103] 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:

[0104] ● load balancing;

[0105] ● re-direction (both in RRC idle and RRC inactive modes) to other frequencies or RATs;

[0106] ● UE context release triggered by the AMF (CN), for instance due to no Downlink (DL) or Uplink (UL) data in the buffer;

[0107] ● suspend indication to send the UE to RRC inactive;

[0108] ● failure to retrieve UE context when UE resumes RRC connection mode from RRC inactive mode.

[0109] The RRC release message may for instance contain any of the following information elements:

[0110] ● redirectedCarrierInfo - information on carriers to re-direct to, which may be inter or intra-RAT frequencies;

[0111] ● cellReselectionPriorities - cell reselection priorities - these may be specifically configured for the UE in the RRCRelease message;

[0112] ● suspendConfig - configuration for RRC inactive;

[0113] ● deprioritisationReq;

[0114] ● waitTime;

[0115] ● measIdleConfig - measurement configuration for idle mode, used to measure and store measurement information to be reported to the network when re-connecting;

[0116] ● sdtConfig - configurations for Short Data Transmissions (allows UE to send a usually smaller amount of data in RRC inactive mode);

[0117] ● srs-PosRRC-Inactive - SRS configuration to be used for RRC inactive positioning.

[0118] Includes the potential following timers:

[0119] - waitTime (T302) - timer to bar the UE from attempting to access;

[0120] - T320 - how long the cell configured cell reselection priorities shall be active;

[0121] - T380 - timer-based RAN Notification Area Update.

[0122] LTE RRC Release

[0123] 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.

[0124] In RRCConnectionRelease (E-UTRAN / LTE version) the following can be signalled:

[0125] ● Release cause

[0126] ○ loadbalancingTAUrequired

[0127] ○ other

[0128] ○ cs-FallbackHighPriority

[0129] ○ rrc-Suspend

[0130] ● RedirectedCarrierInfo

[0131] ○ Contains frequencies of different RATS such as EUTRA, GERAN, utra, cdma2000, NR

[0132] ● idleModeMobilityControlInfo

[0133] ○ frequency priority list which signals different carrier frequencies and their cell reselection priority for different RATs

[0134] ○ T320 which gives the time the frequency priority list is active

[0135] ● cellInfoList

[0136] ○ 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

[0137] ● MeasIdleConfig

[0138] ○ conveys information about measurements to be performed in idle mode, this is used for the purpose of performing faster Carrier Aggregation establishment

[0139] ● Alternative frequency priorities

[0140] ○ tells the UE to apply alternative cell reselection priorities

[0141] ● Release idle mode measurement config

[0142] ○ indicates that the UE shall release the idle / inactive measurement configuration, if it has been configured, used for early CA setup (CA / DC enhancements).

[0143] A first issue with mIAB is that macro cells are large, mIAB cells are smaller. Due to the nature of mIAB cells moving, and potentially moving unpredictably, it may not always be easy to broadcast the correct mIAB 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 mIAB cell assistance information in a more dedicated manner. A deployment example can be found in Figure 6, where an mIAB cell only goes through a very small part of a larger macro cell.

[0144] A second issue with mIAB 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 mIAB cells, there may not be much benefit in mIAB as most real-life deployments heavily rely on both E-UTRAN and NR cells.

[0145] 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 disclosure.

[0146] mIAB Inter-RAT Idle Mode and Inactive Mode Mobility

[0147] In order for a network to get full benefit of mIAB cells, inter-RAT cell reselection from E-UTRAN (non-mIAB as there is no IAB E-UTRAN cell) to mIAB NR is supported in the present disclosure.

[0148] In order for a UE to efficiently perform inter-RAT cell reselection from E-UTRAN to an NR mIAB cell, the network may signal inter-RAT mIAB assistance information in an E-UTRAN node about potential mIAB cells or frequencies. An example of this can be found in Figure 7.

[0149] The inter-RAT mIAB assistance information that is signalled on an E-UTRAN node about an NR mIAB cell may for instance include the following fields:

[0150] ● the presence of mIAB cells on a frequency,

[0151] ○ this can be a flag that indicates that there are mIAB cells on the frequency and if an mIAB cell is detected, the UE may prioritize the frequency;

[0152] ● a list of mIAB cells;

[0153] ● mIAB-specific TreselectionRAT (TreselectionRAT-mIAB),

[0154] ○ this can for instance be shorter compared to the TreselectionNR, which allows for a faster reselection from an EUTRA cell to an NR mIAB cell, this can be general to any mIAB cell, or be specific to a frequency where there are mIAB cells;

[0155] ● reselection-thresholds specific to mIAB cells,

[0156] ○ 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,

[0157] ○ these can be utilized only for the mIAB cells on the frequency.

[0158] The above inter-RAT mIAB assistance information fields may, for instance, be signalled in a System Information Block (SIB), where the most suitable SIB may be SystemInformationBlockType24. Some of the inter-RAT mIAB assistance information fields, such as a list of mIAB cells, the presence of mIAB cells on a frequency and similar, may be signalled per frequency. Some of the fields, such as mIAB-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.

[0159] As the area where it is relevant to perform inter-RAT idle mode mobility may be significantly smaller than the size of a mIAB cell, there may be further information which is signalled, indicating when and where the cell inter-RAT mIAB assistance information is to be applied, or when mIAB 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.

[0160] 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 mIAB cell.

[0161] In one aspect of the disclosure, if there are multiple cells fulfilling the criteria for inter-RAT cell reselection, and only one of the cells is a mIAB cell, the UE may select the mIAB cell. This means that in the inter-RAT cell reselection, the mIAB cell may have higher priority.

[0162] For performing the methods whereby a UE identifies an inter-RAT cell as a mIAB cell, either the cell inter-RAT mIAB 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 neighboring cell in SIB1.

[0163] An example of how broadcasting of the inter-RAT mIAB assistance information may be used is that, when there are no mIAB cells nearby, the network may not broadcast the specific system inter-RAT mIAB assistance information, for example in SIB24, and when the network knows that there may be mIAB cells incoming, the network may start broadcasting the system inter-RAT mIAB assistance information, for example using SIB24. Starting to broadcast the system inter-RAT mIAB 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.

[0164] Configuring mIAB Cell Assistance via RRC Release

[0165] As explained in some of the mIAB issues above, it may be difficult to broadcast appropriate mIAB cell assistance information.

[0166] In one aspect of the disclosure, a UE may be configured with intra-RAT mIAB cell assistance information in a NR mIAB cell when the UE is released to RRC idle mode or RRC inactive mode. The UE may be configured with the intra-RAT mIAB cell assistance information from a NR gNB. The UE may be configured with the intra-RAT mIAB cell assistance information in, for example, an RRC message, such as a RRC Release message. Based on this intra-RAT mIAB cell assistance information, the UE may then connect to the NR mIAB cell. A general figure of this can be seen in Figure 9 and a specification example can be seen in Specification Example #3, below.

[0167] In an aspect of the disclosure, a UE may be configured with inter-RAT mIAB 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 mIAB cell assistance information from an E-UTRAN eNB. The UE may be configured with the inter-RAT mIAB 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.

[0168] The UE may, for instance, be re-directed to an mIAB cell via inter-RAT mIAB cell assistance information or the intra-RAT mIAB cell assistance information in a RRCConnectionRelease message. This may make sense if there is no X2 interface or Xn interface (i.e. an inter-node interface) in between the mIAB cell and the NR / E-UTRA cell.

[0169] In one aspect of the disclosure, the UE may be configured with mIAB cell assistance information when the UE is "re-directed" to another frequency and / or inter-RAT. In the re-direct 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 mIAB cells, or be a flag indicating that the UE shall prioritize mIAB cells when re-directing, i.e. perform cell selection.

[0170] In one aspect of the disclosure, the UE may be configured with mIAB cell assistance information when the UE is configured with dedicated priorities. The mIAB cell assistance information may be inter-RAT mIAB cell assistance information or intra-RAT mIAB cell assistance information. In a further aspect of being configured with dedicated mIAB 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 mIAB, since a mIAB cell moves, it may be problematic for network performance to maintain such mIAB cell assistance information for long as this may become outdated. In an aspect, a separate timer may be introduced for the inter-RAT mIAB cell assistance information. This timer may allow the network to configure a significantly shorter duration or a potentially longer duration for the mIAB cell assistance information.

[0171] The inter-RAT mIAB cell assistance information or intra-RAT mIAB cell assistance information in a RRCConnectionRelease message can be a part of the following configurations:

[0172] - RedirectionInfo (E-UTRAN version) / RedirectedCarrierInfo (NR version),

[0173] - Idle mode control information (E-UTRAN) - this example can be seen in Example #2 below,

[0174] - CellReselectionPriorities (NR).

[0175] For a gNB or an eNB configuring a UE with intra-RAT mIAB 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 mIAB cells in connected mode. This may be potentially for the purpose of eventually performing a handover to one of the mIAB 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 mIAB cells, the gNB may configure the UE with mIAB cell assistance information.

[0176] In an example, a gNB may receive an mIAB on-board indication in RRC connected mode. Thereafter the network may configure a UE with mIAB prioritization information or intra-RAT mIAB 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 IAB discussions. This can be seen in Figure 11.

[0177] In an aspect of the disclosure, the UE may send an indication to the network that it wants to connect to an mIAB cell. This may done via an mIAB-PreferenceIndication 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 UEAssistanceInformation).

[0178] The non-mIAB 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 mIAB cell assistance information.

[0179] 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 mIAB 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.

[0180] As an aspect, if a re-direction or a connection to an mIAB cell results from a UE being released, if the UE is barred from access to an mIAB 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 mIAB cells. This may help with overload cases, where, for instance, a set of mIAB 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.

[0181] Considering the time interval measured by the T302 timer to apply to mIAB cells may also be performed when a UE camps on and then connects to the mIAB 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.

[0182] Specification Examples

[0183] Example #1

[0184] Specification changes are shown inbold.

[0185] 36.331 Release 17 V17.5.0, June 2023

[0186] SystemInformationBlockType24:[Table 1]

[0187] The IESystemInformationBlockType24contains 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.

[0188] [Table 1]

[0189] SystemInformationBlockType24 information element

[0190]

[0191]

[0192]

[0193]

[0194] Example #2

[0195] Specification changes are shown inbold.

[0196] 36.331 Release 17 V17.5.0, June 2023

[0197] RRCConnectionRelease:[Table 2]

[0198] TheRRCConnectionReleasemessage is used to command the release of an RRC connection, or to complete an UP-EDT procedure.

[0199] ·Signalling radio bearer: SRB1

[0200] ·RLC-SAP: AM

[0201] ·Logical channel: DCCH

[0202] ·Direction: E UTRAN to UE

[0203] [Table 2]

[0204]

[0205]

[0206]

[0207]

[0208] Example #3

[0209] Specification changes are shown inbold.

[0210] 38.331 Release 17 V17.5.0, June 2023

[0211] RRCRelease Message:[Table 3]

[0212] TheRRCRelease messageis used to command the release of an RRC connection or the suspension of the RRC connection.

[0213] · Signalling radio bearer: SRB1

[0214] · RLC-SAP: AM

[0215] · Logical channel: DCCH

[0216] · Direction: Network to UE

[0217] [Table 3]

[0218]

[0219]

[0220]

[0221]

[0222] Figure 12 is a flow chart a method 1200 for mobile IAB inter RAT mobility, according to embodiments as disclosed herein.

[0223] Referring to Figure 12, in S1210, according to an embodiment, the UE 1400, from a BS (base station), may obtain a SIB (system information block) including information related to an inter RAT (radio access technology) cell. The information related to the inter RAT cell may include at least one of: information on frequencies with one or more mobile IAB (Integrated Access and Backhaul) cells or information on a list of one or more mobile IAB cells. The information on the frequencies with one or more mobile IAB cells may indicate that the one or more mobile IAB cells are deployed on the inter RAT frequency.

[0224] In S1220, in case that a inter RAT mobile IAB cell is detected, the UE 1400 may consider a inter RAT frequency for the inter RAT mobile IAB cell to be the highest priority for cell reselection.

[0225] Figure 13 is a flow chart a method 1300 for mobile IAB inter RAT mobility, according to embodiments as disclosed herein.

[0226] Referring to Figure 13, in S1310, according to an embodiment, the network entity 1500 may broadcast a SIB (system information block) including information related to an inter RAT (radio access technology) cell. The information related to the inter RAT cell may include at least one of: information on frequencies with one or more mobile IAB (Integrated Access and Backhaul) cells or information on a list of one or more mobile IAB cells. The information on the frequencies with one or more mobile IAB cells may indicate that the one or more mobile IAB cells are deployed on the inter RAT frequency.

[0227] In S1320, in case that a inter RAT mobile IAB cell is detected, a inter RAT frequency for the inter RAT mobile IAB cell is considered to be the highest priority for cell reselection.

[0228] Figure 14 is a block diagram illustrating a UE 1400 according to another embodiment of the present disclosure.

[0229] Referring to the Figure 14, the UE 1400 may include a processor 1410, a transceiver 1420 and a memory 1430. However, all of the illustrated components are not essential. The UE 1400 may be implemented by more or less components than those illustrated in Figure 14. In addition, the processor 1410 and the transceiver 1420 and the memory 1430 may be implemented as a single chip according to another embodiment.

[0230] The aforementioned components will now be described in detail.

[0231] The processor 1410 may include one or more processors or other processing devices that control the proposed function, process, and / or method. Operation of the UE 1400 aforementioned in this disclosure may be implemented by the processor 1410.

[0232] The at least one processor 1410 may include various processing circuitry and / or multiple processors. For example, as used herein, including the claims, the term "processor" may include various processing circuitry, including at least one processor, wherein one or more of at least one processor, individually and / or collectively in a distributed manner, may be configured to perform various functions described herein. As used herein, when "a processor", "at least one processor", and "one or more processors" are described as being configured to perform numerous functions, these terms cover situations, for example and without limitation, in which one processor performs some of recited functions and another processor(s) performs other of recited functions, and also situations in which a single processor may perform all recited functions. Additionally, the at least one processor may include a combination of processors performing various of the recited / disclosed functions, e.g., in a distributed manner. At least one processor may execute program instructions to achieve or perform various functions.

[0233] The transceiver 1420 may include a RF transmitter for up-converting and amplifying a transmitted signal, and a RF receiver for down-converting a frequency of a received signal. However, according to another embodiment, the transceiver 1420 may be implemented by more or less components than those illustrated in components.

[0234] The transceiver 1420 may be connected to the processor 1410 and transmit and / or receive a signal. The signal may include control information and data. In addition, the transceiver 1420 may receive the signal through a wireless channel and output the signal to the processor 1410. The transceiver 1420 may transmit a signal output from the processor 1410 through the wireless channel.

[0235] The memory 1430 may store the control information or the data included in a signal obtained by the UE 1400. The memory 1430 may be connected to the processor 1410 and store at least one instruction or a protocol or a parameter for the proposed function, process, and / or method. The memory 1430 may include read-only memory (ROM) and / or random access memory (RAM) and / or hard disk and / or CD-ROM and / or DVD and / or other storage devices.

[0236] Figure 15 is a block diagram of a network entity 1500 according to an embodiment of the present disclosure.

[0237] The network entity 1500 can be used to realize the DU, CU-UP, CU-CP, gNB, eNB source base station, destination station, source DU, source CU-UP, destination DU, destination CU-UP, destination CU-CP, master base station, secondary base station, OAM, UDM, AMF, SMF or UPF, etc. of the present disclosure.

[0238] Referring to the Figure 15, the network entity 1500 may include at least one processor 1510, a transceiver 1520 and a memory 1530. However, all of the illustrated components are not essential. The network entity 1500 may be implemented by more or less components than those illustrated in Figure 15. In addition, the at least one processor 1510 and the transceiver 1520 and the memory 1530 may be implemented as a single chip according to another embodiment.

[0239] The aforementioned components will now be described in detail.

[0240] The at least one processor 1510 may include one or more processors or other processing devices that control the proposed function, process, and / or method. Operation of the network entity 1500 aforementioned in this disclosure may be implemented by the processor 1510. The processor 1510 may execute one or more instructions stored in the memory 1530 to operation as described above.

[0241] The at least one processor 1510 may include various processing circuitry and / or multiple processors. For example, as used herein, including the claims, the term "processor" may include various processing circuitry, including at least one processor, wherein one or more of at least one processor, individually and / or collectively in a distributed manner, may be configured to perform various functions described herein. As used herein, when "a processor", "at least one processor", and "one or more processors" are described as being configured to perform numerous functions, these terms cover situations, for example and without limitation, in which one processor performs some of recited functions and another processor(s) performs other of recited functions, and also situations in which a single processor may perform all recited functions. Additionally, the at least one processor may include a combination of processors performing various of the recited / disclosed functions, e.g., in a distributed manner. At least one processor may execute program instructions to achieve or perform various functions.

[0242] The transceiver 1520 may include a RF transmitter for up-converting and amplifying a transmitted signal, and a RF receiver for down-converting a frequency of a received signal. However, according to another embodiment, the transceiver 1520 may be implemented by more or less components than those illustrated in components.

[0243] The transceiver 1520 may be connected to the processor 1510 and transmit and / or receive a signal. The signal may include control information and data. In addition, the transceiver 1520 may receive the signal through a wireless channel and output the signal to the processor 1510. The transceiver 1520 may transmit a signal output from the processor 1510 through the wireless channel.

[0244] The memory 1530 may store the control information or the data included in a signal obtained by the network entity 1500. The memory 1530 may be connected to the processor 1510 and store at least one instruction or a protocol or a parameter for the proposed function, process, and / or method. The memory 1530 may include read-only memory (ROM) and / or random access memory (RAM) and / or hard disk and / or CD-ROM and / or DVD and / or other storage devices.

[0245] 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. For example, in the following examples, a network may include one or more IAB nodes.

[0246] 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.

[0247] The same or similar components may be designated by the same or similar reference numerals, although they may be illustrated in different drawings.

[0248] 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.

[0249] 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.

[0250] 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.

[0251] 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.

[0252] 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.

[0253] 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.

[0254] While the present disclosure 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 present disclosure, as defined by the appended claims.

[0255] In addition, computer-readable storage media may be provided in the form of non-transitory storage media. The 'non-transitory storage medium' is a tangible device and only means that it does not contain a signal (e.g., electromagnetic waves). This term does not distinguish a case in which data is stored semi-permanently in a storage medium from a case in which data is temporarily stored. For example, the non-transitory recording medium may include a buffer in which data is temporarily stored.

[0256] The specific examples provided to explain the embodiments according to the present disclosure are merely a combination of each standard, method, detail method, and operation, and the various embodiments described herein can be performed through a combination of at least two or more techniques among the various techniques described. In addition, at this time, it can be performed according to a method determined through a combination of one or at least two or more of the aforementioned techniques. For example, it may be possible to perform a combination of parts of the operation of one embodiment with parts of the operation of another embodiment.

[0257] Abbreviations / Definitions

[0258] In the present disclosure, the following abbreviations and definitions in table 4 may be used.

[0259] [Table 4]

[0260]

Claims

1.A method of a UE(user equipment) in a wireless communication system, comprising:obtaining, from a BS(base station), a SIB(system information block) including information related to an inter RAT(radio access technology) cell,wherein the information related to the inter RAT cell includes at least one of: information on frequencies with one or more mobile IAB(Integrated Access and Backhaul) cells or information on a list of one or more mobile IAB cells; andin case that a inter RAT mobile IAB cell is detected, considering a inter RAT frequency for the inter RAT mobile IAB cell to be the highest priority for cell reselection.2.The method of claim 1, the information on the frequencies with one or more mobile IAB cells indicates that the one or more mobile IAB cells are deployed on the inter RAT frequency.3.The method of claim 1, the SIB is a SIB Type 24.4.The method of claim 1, further comprising:obtaining a SIB 1 including information indicating a inter RAT cell is a mobile IAB cell; andidentifying the inter RAT mobile-IAB cell, based on the information included in the SIB 1.5.The method of claim 1,the BS is an E-UTRAN(Evolved-Universal Terrestrial Radio Access Network) cell,the inter RAT mobile IAB cell is an NR(new radio) mobile IAB cell, andthe inter RAT frequency is an NR frequency.6.The method of claim 1, further comprising:receiving, from the BS, a radio resource control (RRC) release message including inter RAT mobile IAB cell assistance information; andbased on the inter RAT mobile IAB cell assistance information included in the RRC release message, redirecting to the inter RAT mobile IAB cell.7.A method of a BS(base station) in a wireless communication system, comprising:broadcasting a SIB(system information block) including information related to an inter RAT(radio access technology) cell,wherein the information related to the inter RAT cell includes at least one of: information on frequencies with one or more mobile IAB(Integrated Access and Backhaul) cells or information on a list of one or more mobile IAB cells; andwherein in case that a inter RAT mobile IAB cell is detected, a inter RAT frequency for the inter RAT mobile IAB cell is considered to be the highest priority for cell reselection.8.A UE(user equipment) in a wireless communication system, comprising:memory storing one or more instructions; andat least one processor configured to execute the one or more instructions to:obtain, from a BS(base station), a SIB(system information block) including information related to an inter RAT(radio access technology) cell,wherein the information related to the inter RAT cell includes at least one of: information on frequencies with mobile IAB(Integrated Access and Backhaul) cells and information on a list of one or more mobile IAB cells; andin case that a inter RAT mobile IAB cell is detected, consider a inter RAT frequency for the inter RAT mobile IAB cell to be the highest priority for cell reselection.9.The UE of claim 8, the information on the frequencies with one or more mobile IAB cells indicates that the one or more mobile IAB cells are deployed on the inter RAT frequency.10.The UE of claim 8, the SIB is a SIB Type 24.11.The UE of claim 8, the at least one processor further configured to execute the one or more instructions to:obtain a SIB 1 including information indicating a inter RAT cell is a mobile IAB cell; andidentify the inter RAT mobile IAB cell, based on the information included in the SIB 1.12.The UE of claim 8,the BS is an E-UTRAN(Evolved-Universal Terrestrial Radio Access Network) cell,the inter RAT mobile IAB cell is an NR(new radio) mobile IAB cell, andthe inter RAT frequency is an NR frequency.13.The UE of claim 8, the at least one processor further configured to execute the one or more instructions to:receiving, from the BS, a radio resource control (RRC) release message including inter RAT mobile IAB cell assistance information; andbased on the inter RAT mobile IAB cell assistance information included in the RRC release message, redirecting to the inter RAT mobile IAB cell.14.A BS(base station) in a wireless communication system, comprising:memory storing one or more instructions; andat least one processor configured to execute the one or more instructions to:broadcast a SIB(system information block) including information related to an inter RAT(radio access technology) cell,wherein the information related to the inter RAT cell includes at least one of: information on frequencies with one or more mobile IAB(Integrated Access and Backhaul) cells or information on a list of one or more mobile IAB cells, andwherein in case that a inter RAT mobile IAB cell is detected, a inter RAT frequency for the inter RAT mobile IAB cell is considered to be the highest priority for cell reselection.15.The BS of claim 14, the information on the frequencies with one or more mobile IAB cells indicates that the one or more mobile IAB cells are deployed on the inter RAT frequency.

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