Communication control method and user device

Abstract

A communication control method according to one aspect of the present invention is used in a cellular communication system. The communication control method includes: a step in which a relay node reports an offset value for a mobile relay node; and a step in which a user device executes an intra frequency cell reselection procedure by using the offset value for the mobile relay node.

Description

[Technical Field]

[0001] This disclosure relates to a communication control method used in a cellular communication system. [Background technology]

[0002] In the 3GPP (Third Generation Partnership Project), a standardization project for cellular communication systems, the introduction of a new type of relay node called an IAB (Integrated Access and Backhaul) node is being considered (see, for example, Non-Patent Document 1). One or more relay nodes intervene in communication between a base station and user equipment, and relay this communication. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] 3GPP TS 38.300 V17.2.0(2022-09) [Overview of the Initiative]

[0004] The first aspect of the communication control method is a communication control method used in a cellular communication system. The communication control method includes the steps of a relay node notifying an offset value for a mobile relay node, and a user device executing an intra-frequency cell reselection procedure using the offset value for the mobile relay node.

[0005] The second aspect of the communication control method is a communication control method used in a cellular communication system. The communication control method includes the step of a user device receiving from a cell HSDN cell information indicating that the cell is a high-speed dedicated network (HSDN) cell and mobile relay node cell type information indicating that the cell is a mobile relay node cell. The communication control method also includes the step of the user device executing an inter-frequency cell reselection procedure without considering the cell as the lowest priority cell when it is in a low-speed moving state. [Brief explanation of the drawing]

[0006] [Figure 1] Figure 1 shows an example configuration of a cellular communication system according to one embodiment. [Figure 2] Figure 2 shows the relationship between IAB nodes, parent nodes, and child nodes. [Figure 3] Figure 3 shows an example configuration of a gNB (base station) according to one embodiment. [Figure 4] Figure 4 shows an example configuration of an IAB node (relay node) according to one embodiment. [Figure 5] Figure 5 shows an example configuration of a UE (User Equipment) according to one embodiment. [Figure 6] Figure 6 shows an example of a protocol stack for IAB-MT RRC and NAS connections. [Figure 7] Figure 7 shows an example of a protocol stack for the F1-U protocol. [Figure 8] Figure 8 shows an example of a protocol stack for the F1-C protocol. [Figure 9] Figure 9 is a diagram illustrating an example of operation according to the first embodiment. [Figure 10] Figures 10(A) and 10(B) are diagrams illustrating an example of operation according to the first embodiment. [Figure 11] Figure 11 is a diagram illustrating an example of operation according to the second embodiment. [Figure 12] FIG. 12 is a diagram showing scenarios and sub-cases of cell reselection of a UE. [Figure 13] FIG. 13 is a diagram showing RACH less handover settings in MobilityControlInfo using applicable timing advance (TA) and uplink grant information.

Embodiments for Carrying Out the Invention

[0007] A cellular communication system according to an embodiment will be described while referring to the drawings. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. "

[0008] [First Embodiment]

[0009] (Configuration of Cellular Communication System) A configuration example of a cellular communication system according to an embodiment will be described. A cellular communication system 1 according to an embodiment is a 3GPP 5G system. Specifically, the radio access method in the cellular communication system 1 is NR (New Radio), which is a 5G radio access method. However, LTE (Long Term Evolution) may be at least partially applied to the cellular communication system 1. Also, a future cellular communication system such as 6G may be applied to the cellular communication system 1.

[0010] FIG. 1 is a diagram showing a configuration example of a cellular communication system 1 according to an embodiment.

[0011] As shown in FIG. 1, the cellular communication system 1 includes a 5G core network (5GC) 10, user equipment (UE: User Equipment) 100, base station devices (hereinafter sometimes referred to as "base stations") 200-1, 200-2, and IAB nodes 300-1, 300-2. The base station 200 may be called a gNB. "

[0012] In the following, an example where the base station 200 is an NR base station will be mainly described, but the base station 200 may be an LTE base station (i.e., eNB).

[0013] Note that in the following, the base stations 200-1 and 200-2 may be referred to as gNB200 (or base station 200), and the IAB nodes 300-1 and 300-2 may be referred to as IAB node 300, respectively.

[0014] The 5GC 10 has an AMF (Access and Mobility Management Function) 11 and a UPF (User Plane Function) 12. The AMF 11 is a device that performs various mobility controls for the UE 100. The AMF 11 manages information on the area where the UE 100 is located by communicating with the UE 100 using NAS (Non-Access Stratum) signaling. The UPF 12 is a device that performs transfer control of user data.

[0015] Each gNB200 is a fixed radio communication node that manages one or more cells. A cell is a term used to indicate the smallest unit of a radio communication area. A cell may be used as a term to indicate a function or resource for performing radio communication with the UE 100. One cell belongs to one carrier frequency. In the following, the cell and the base station may be used without distinction.

[0016] Each gNB200 is interconnected with the 5GC 10 via an interface called the NG interface. In FIG. 1, two gNB200-1 and gNB200-2 connected to the 5GC 10 are illustrated.

[0017] Each gNB200 may be divided into a Central Unit (CU) and a Distributed Unit (DU). The CU and DU are interconnected via an interface called the F1 interface. The F1 protocol is a communication protocol between the CU and DU, and consists of the F1-C protocol, which is the control plane protocol, and the F1-U protocol, which is the user plane protocol.

[0018] Cellular communication system 1 supports IAB, which enables wireless relay of NR access using NR for backhaul. Donor gNB200-1 (or donor node; hereinafter sometimes referred to as "donor node") is the network-side NR backhaul termination node and is a donor base station with additional functions to support IAB. Backhaul can be multi-hop, via multiple hops (i.e., multiple IAB nodes 300).

[0019] Figure 1 shows an example where IAB node 300-1 is wirelessly connected to donor node 200-1, and IAB node 300-2 is wirelessly connected to IAB node 300-1, with the F1 protocol being transmitted over two backhaul hops.

[0020] The UE100 is a mobile wireless communication device that communicates wirelessly with a cell. The UE100 can be any device that communicates wirelessly with the gNB200 or IAB node 300. For example, the UE100 may be a mobile phone terminal and / or a tablet terminal, a notebook PC, a sensor or a device installed on a sensor, a vehicle or a device installed on a vehicle, an aircraft or a device installed on an aircraft. The UE100 connects wirelessly to the IAB node 300 or gNB200 via an access link. Figure 1 shows an example of the UE100 connecting wirelessly to IAB node 300-2. The UE100 communicates indirectly with donor node 200-1 via IAB node 300-2 and IAB node 300-1.

[0021] Figure 2 shows an example of the relationship between IAB node 300, parent nodes, and child nodes.

[0022] As shown in Figure 2, each IAB node 300 has an IAB-DU, which corresponds to the base station function unit, and an IAB-MT (Mobile Termination), which corresponds to the user equipment function unit.

[0023] On the IAB-MT's NR Uu radio interface, adjacent nodes (i.e., higher-level nodes) are called parent nodes. A parent node is the DU of the parent IAB node or donor node 200. The radio link between the IAB-MT and the parent node is called a backhaul link (BH link). Figure 2 shows an example where the parent nodes of IAB node 300 are IAB nodes 300-P1 and 300-P2. The direction toward the parent node is called upstream. From the perspective of UE100, the higher-level node of UE100 may be a parent node.

[0024] Adjacent nodes (i.e., lower-level nodes) on the NR access interface of an IAB-DU are called child nodes. The IAB-DU manages cells, similar to the gNB200. The IAB-DU terminates the NR Uu radio interface to the UE100 and lower-level IAB nodes. The IAB-DU supports the F1 protocol to the CU of donor node 200-1. Figure 2 shows an example where the child nodes of IAB node 300 are IAB nodes 300-C1 to 300-C3, but the child nodes of IAB node 300 may also include the UE100. The direction toward child nodes is called downstream.

[0025] Furthermore, all IAB nodes 300 connected to the donor node 200 via one or more hops form a directed acyclic graph (DAG) topology (hereinafter sometimes referred to as "topology") with the donor node 200 as the root. In this topology, as shown in Figure 2, adjacent nodes on the IAB-DU interface become child nodes, and adjacent nodes on the IAB-MT interface become parent nodes. The donor node 200 centrally manages, for example, the resources, topology, and route management of the IAB topology. The donor node 200 is a gNB that provides network access to the UE100 via the backhaul link and access link network.

[0026] (Base station configuration) Next, the configuration of the gNB200, which is a base station according to the embodiment, will be described. Figure 3 is a diagram showing an example of the configuration of the gNB200. As shown in Figure 3, the gNB200 has a wireless communication unit 210, a network communication unit 220, and a control unit 230.

[0027] The wireless communication unit 210 performs wireless communication with the UE 100 and with the IAB node 300. The wireless communication unit 210 includes a receiving unit 211 and a transmitting unit 212. The receiving unit 211 performs various types of reception under the control of the control unit 230. The receiving unit 211 includes an antenna and converts the wireless signal received by the antenna into a baseband signal (received signal) (downconvert) and outputs it to the control unit 230. The transmitting unit 212 performs various types of transmission under the control of the control unit 230. The transmitting unit 212 includes an antenna and converts the baseband signal (transmitted signal) output by the control unit 230 into a wireless signal (upconvert) and transmits it from the antenna.

[0028] The network communication unit 220 performs wired (or wireless) communication with 5GC10 and with other adjacent gNB200s. The network communication unit 220 has a receiving unit 221 and a transmitting unit 222. The receiving unit 221 performs various types of reception under the control of the control unit 230. The receiving unit 221 receives signals from the outside and outputs the received signals to the control unit 230. The transmitting unit 222 performs various types of transmission under the control of the control unit 230. The transmitting unit 222 transmits the transmission signals output by the control unit 230 to the outside.

[0029] The control unit 230 performs various controls in the gNB200. The control unit 230 includes at least one memory and at least one processor electrically connected to the memory. The memory stores programs executed by the processor and information used for processing by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation, demodulation, encoding, decoding, etc., of the baseband signal. The CPU executes programs stored in the memory and performs various processing. The processor performs processing for each layer described later. In each of the embodiments shown below, the control unit 230 may perform each processing or operation in the gNB200.

[0030] (Configuration of relay nodes) Next, the configuration of the IAB node 300, which is a relay node (or relay node device; hereinafter sometimes referred to as "relay node") according to the embodiment, will be described. Figure 4 is a diagram showing an example of the configuration of the IAB node 300. As shown in Figure 4, the IAB node 300 has a wireless communication unit 310 and a control unit 320. The IAB node 300 may have multiple wireless communication units 310.

[0031] The wireless communication unit 310 performs wireless communication with the gNB200 (BH link) and wireless communication with the UE100 (access link). The wireless communication unit 310 for BH link communication and the wireless communication unit 310 for access link communication may be provided separately.

[0032] The wireless communication unit 310 includes a receiving unit 311 and a transmitting unit 312. The receiving unit 311 performs various types of reception under the control of the control unit 320. The receiving unit 311 includes an antenna and converts the wireless signal received by the antenna into a baseband signal (received signal) (downconvert) and outputs it to the control unit 320. The transmitting unit 312 performs various types of transmission under the control of the control unit 320. The transmitting unit 312 includes an antenna and converts the baseband signal (transmitted signal) output by the control unit 320 into a wireless signal (upconvert) and transmits it from the antenna.

[0033] The control unit 320 performs various controls in the IAB node 300. The control unit 320 includes at least one memory and at least one processor electrically connected to the memory. The memory stores programs executed by the processor and information used for processing by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation, demodulation, encoding, and decoding of baseband signals. The CPU executes programs stored in the memory and performs various processes. The processor performs processing for each layer described later. In each of the embodiments shown below, the control unit 320 may perform each process or operation in the IAB node 300.

[0034] (User device configuration) Next, the configuration of the user device UE100 according to the embodiment will be described. Figure 5 is a diagram showing an example of the configuration of UE100. As shown in Figure 5, UE100 has a wireless communication unit 110 and a control unit 120.

[0035] The wireless communication unit 110 performs wireless communication on the access link, i.e., wireless communication with the gNB200 and wireless communication with the IAB node 300. The wireless communication unit 110 may also perform wireless communication on the side link, i.e., wireless communication with other UE100s. The wireless communication unit 110 has a receiving unit 111 and a transmitting unit 112. The receiving unit 111 performs various types of reception under the control of the control unit 120. The receiving unit 111 includes an antenna and converts the wireless signal received by the antenna into a baseband signal (received signal) (downconvert) and outputs it to the control unit 120. The transmitting unit 112 performs various types of transmission under the control of the control unit 120. The transmitting unit 112 includes an antenna and converts the baseband signal (transmitted signal) output by the control unit 120 into a wireless signal (upconvert) and transmits it from the antenna.

[0036] The control unit 120 performs various controls in the UE 100. The control unit 120 includes at least one memory and at least one processor electrically connected to the memory. The memory stores programs executed by the processor and information used for processing by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation, demodulation, encoding, and decoding of baseband signals. The CPU executes programs stored in the memory and performs various processes. The processor performs processing for each layer described later. The control unit 120 may perform each process in the UE 100 in each of the embodiments shown below.

[0037] (Protocol stack configuration) Next, the configuration of the protocol stack according to the embodiment will be described. Figure 6 shows an example of a protocol stack for IAB-MT RRC connection and NAS connection.

[0038] As shown in Figure 6, the IAB-MT of IAB node 300-2 has a physical (PHY) layer, a MAC (Medium Access Control) layer, an RLC (Radio Link Control) layer, a PDCP (Packet Data Convergence Protocol) layer, an RRC (Radio Resource Control) layer, and a NAS (Non-Access Stratum) layer.

[0039] The PHY layer performs encoding and decoding, modulation and demodulation, antenna mapping and demapping, and resource mapping and demapping. Data and control information are transmitted between the PHY layer of IAB-MT at IAB node 300-2 and the PHY layer of IAB-DU at IAB node 300-1 via a physical channel.

[0040] The MAC layer performs data priority control, retransmission processing using Hybrid Automatic Repeat request (HARQ), and random access procedures. Data and control information are transmitted between the MAC layer of IAB-MT on IAB node 300-2 and the MAC layer of IAB-DU on IAB node 300-1 via a transport channel. The MAC layer of IAB-DU includes a scheduler. The scheduler determines the transport format (transport block size, modulation and coding scheme (MCS)) and allocated resource blocks for the up and down links.

[0041] The RLC layer uses the functions of the MAC layer and PHY layer to transmit data to the receiving RLC layer. Data and control information are transmitted between the RLC layer of IAB-MT on IAB node 300-2 and the RLC layer of IAB-DU on IAB node 300-1 via a logical channel.

[0042] The PDCP layer performs header compression / decompression, and encryption / decryption. Data and control information are transmitted between the PDCP layer of IAB-MT on IAB node 300-2 and the PDCP layer on donor node 200 via a wireless bearer.

[0043] The RRC layer controls the logical channel, transport channel, and physical channel in response to the establishment, re-establishment, and release of the radio bearer. RRC signaling for various settings is transmitted between the RRC layer of the IAB-MT on IAB node 300-2 and the RRC layer of donor node 200. If there is an RRC connection with donor node 200, the IAB-MT is in the RRC connected state. If there is no RRC connection with donor node 200, the IAB-MT is in the RRC idle state.

[0044] The NAS layer, located above the RRC layer, handles session management and mobility management, among other things. NAS signaling is transmitted between the NAS layer of IAB-MT on IAB node 300-2 and AMF11.

[0045] Figure 7 shows the protocol stack for the F1-U protocol. Figure 8 shows the protocol stack for the F1-C protocol. Here, an example is shown where donor node 200 is divided into CU and DU.

[0046] As shown in Figure 7, each of the IAB-MT on IAB node 300-2, the IAB-DU on IAB node 300-1, the IAB-MT on IAB node 300-1, and the DU on donor node 200 has a BAP (Backhaul Adaptation Protocol) layer as a layer above the RLC layer. The BAP layer is the layer that performs routing and bearer mapping / demapping. In backhaul, routing across multiple hops is possible because the IP layer is transmitted through the BAP layer.

[0047] In each backhaul link, the BAP layer's PDUs (Protocol Data Units) are transmitted via backhaul RLC channels (BH NR RLC channels). By configuring multiple backhaul RLC channels in each BH link, traffic prioritization and QoS (Quality of Service) control are possible. The mapping between BAP PDUs and backhaul RLC channels is performed by the BAP layer of each IAB node 300 and the BAP layer of the donor node 200.

[0048] As shown in Figure 8, the protocol stack of the F1-C protocol has an F1AP layer and an SCTP layer instead of the GTP-U layer and UDP layer shown in Figure 7.

[0049] In the following, the processes or operations performed by the IAB-DU and IAB-MT of the IAB may be described simply as "IAB processes or operations." For example, the transmission of a BAP layer message from the IAB-DU of IAB node 300-1 to the IAB-MT of IAB node 300-2 will be described as IAB node 300-1 transmitting the message to IAB node 300-2. Similarly, the processes or operations of the DU or CU of donor node 200 may be described simply as "donor node processes or operations."

[0050] Furthermore, the upstream direction and the uplink (UL) direction may not be distinguished. Additionally, the downstream direction and the downlink (DL) direction may not be distinguished.

[0051] (Mobile IAB node) Currently, 3GPP is considering the introduction of mobile IAB nodes. A mobile IAB node is, for example, an IAB node that is in motion. A mobile IAB node may be a mobile IAB node, or an IAB node that has the capability to move, or an IAB node that is currently stationary but is certain to move in the future (or is expected to move in the future).

[0052] A mobile IAB node allows, for example, a UE100 under the mobile IAB node to move along with the mobile IAB node while receiving services from it. For example, a user (or UE100) riding in a vehicle could receive services via a mobile IAB node installed in the vehicle.

[0053] On the other hand, in contrast to mobile IAB nodes, there are also IAB nodes that do not move. Such IAB nodes are sometimes called intermediate IAB nodes. An intermediate IAB node is, for example, an IAB node that does not move. Alternatively, an intermediate IAB node may be a stationary IAB node. Alternatively, an intermediate IAB node may be an IAB node that remains stationary (or does not move) in its installation location. Alternatively, an intermediate IAB node may be an IAB node that remains stationary without moving. An intermediate IAB node may be a fixed IAB node.

[0054] A mobile IAB node can also connect to an intermediate IAB node. Furthermore, a mobile IAB node can connect to donor node 200. A mobile IAB node can also change its connection destination through migration or handover. The source of the connection may be an intermediate IAB node. The source of the connection may also be donor node 200. Furthermore, the destination may be an intermediate IAB node. The destination of the connection may also be donor node 200.

[0055] In the following, the terms "migration" and "handover" of a moving IAB node may not be used interchangeably.

[0056] Furthermore, in the following, a moving IAB node may also be referred to as a "mobile IAB node." The same moving IAB node may also be referred to as a "migrating IAB node." In either case, it may be written as a moving IAB node.

[0057] (Cell reselection procedure) Next, the cell reselection procedure according to the first embodiment will be described.

[0058] A UE100 in an RRC idle or RRC inactive state performs a cell reselection procedure to move from the current serving cell to an adjacent cell. Specifically, the UE100 identifies the adjacent cell to which it should camp on using the cell reselection procedure and reselects the identified adjacent cell. When the current serving cell and the adjacent cell have the same frequency (carrier frequency), it is called an intra-frequency, and when the current serving cell and the adjacent cell have different frequencies (carrier frequencies), it is called an inter-frequency. The current serving cell and the adjacent cell may be managed by the same gNB200. The current serving cell and the adjacent cell may be managed by different gNB200s.

[0059] There are two types of cell reselection procedures: intra-frequency cell reselection and inter-frequency cell reselection.

[0060] The intra-frequency cell reselection procedure reselects cells based on their ranking. For example, the intra-frequency cell reselection procedure performs the following processes:

[0061] Firstly, the UE100 performs a measurement process to measure the wireless quality for both the serving cell and the adjacent cells. Specifically, the UE100 measures the RSRP and RSRQ of the CD-SSB (Cell Defining-Synchronization Signal and PBCH block) for both the serving cell and the adjacent cells.

[0062] Secondly, UE100 calculates the ranking criterion for the serving cell (Rs) and the ranking criterion for adjacent cells (Rn) for all cells that satisfy the cell selection criterion S. Rs and Rn are calculated using the following formulas, respectively.

[0063] Rs=Q meas,s +Q hyst -Qoffset temp ...(1) Rn=Q meas,n -Qoffset-Qoffset temp ...(2) In equation (1), Q meas,s This represents the Reference Signal Received Power (RSRP) (measured value) for the serving cell. Also, in equation (2), Q meas,n This represents the RSRP (measured value) relative to adjacent cells. Qoffset is an offset value for adjusting the RSRP. temp This is a temporary offset value.

[0064] In UE100, the highest-ranked cell is basically re-selected from the two ranking criteria, Rs and Rn.

[0065] Here, as shown in equation (2), an offset value (Qoffset) is used for Rn. The Qoffset is provided from gNB200 to UE100 using broadcast signaling (e.g., System Information Block (SIB)). The Qoffset can be adjusted per frequency or per cell. By adjusting the Qoffset, the network can control the ease of reselection between the serving cell and adjacent cells.

[0066] The cell selection criterion S is the criterion for selecting cells where the RSRP exceeds the minimum RSRP requirement level and the RSRQ exceeds the minimum RSRQ requirement level.

[0067] On the other hand, the inter-frequency cell reselection procedure performs cell reselection based on absolute frequency priority. Frequency priority is provided from gNB200 to UE100 via broadcast signaling (e.g., system information block) or dedicated signaling (e.g., RRC release (RRCRelease) message). The inter-frequency cell reselection procedure performs the following processes, for example:

[0068] Firstly, the UE100 performs a measurement process to measure the radio quality of both the serving cell and adjacent cells. Specifically, the UE100 always measures the radio quality of frequencies with a higher priority than the current serving cell's frequency priority. Furthermore, for frequencies with the same or lower priority as the current serving cell's frequency priority, the UE100 measures the radio quality of frequencies with the same or lower priority if the current serving cell's radio quality falls below a predetermined quality.

[0069] Secondly, UE100 performs a cell reselection process to re-select the cell to which it will camp on, based on the measurement results. Specifically, UE100 may reselect a cell to an adjacent cell if the frequency priority of the adjacent cell is higher than the priority of the current serving cell, and the adjacent cell meets a predetermined quality standard (i.e., the minimum required quality standard) for a predetermined period. If the frequency priority of the adjacent cell is the same as the priority of the current serving cell, UE100 may rank the wireless quality of the adjacent cell and reselect a cell to an adjacent cell that has a higher rank than the current serving cell for a predetermined period. If the frequency priority of the adjacent cell is lower than the priority of the current serving cell, and the wireless quality of the current serving cell remains below a certain threshold, and the wireless quality of the adjacent cell remains above another threshold for a predetermined period, UE100 may reselect a cell to that adjacent cell.

[0070] The example described above illustrates how UE100 performs the cell reselection procedure, but it is also possible for IAB-MT on IAB node 300 to perform the cell reselection procedure.

[0071] (Communication control method according to the first embodiment) Next, a communication control method according to the first embodiment will be described. In the first embodiment, an intra-frequency cell reselection procedure in a mobile IAB node will be described.

[0072] A mobile IAB node can broadcast mobile-IAB cell type information (or mobile relay node cell type information) indicating that it is a mobile IAB node. This mobile-IAB cell type information can, for example, assist in the movement of a UE100 that is in an RRC idle or RRC inactive state. The mobile-IAB cell type information is, for example, 1 bit of information. In addition, along with (or instead of) the mobile-IAB cell type information, the mobile IAB node may also broadcast speed information representing its speed. In this way, by broadcasting mobile-IAB cell type information (and / or speed information), a UE100 that receives this information can understand that the cell that broadcast the information is a mobile IAB node cell.

[0073] On the other hand, in the intra-frequency cell reselection procedure, reselection is performed by ranking using equations (1) and (2), as described above. Here, let's assume that the intra-frequency cell reselection procedure is applied to a mobile IAB node. Even in such a case, for example, by adjusting the Qoffset in equation (2), the network side can control the ease of reselection for the cells of the mobile IAB node (hereinafter, these cells may be referred to as "mobile IAB cells").

[0074] However, there is only one type of Qoffset. In a non-mobile IAB node, when a mobile IAB node flows into the cell of the non-mobile IAB node (hereinafter, such cell may be referred to as a "non-mobile IAB cell." A "non-mobile IAB cell" may include cells provided by a fixed (stationary) IAB node. A "non-mobile IAB cell" may also include cells provided by a conventional base station (such as a macrocell)), the Qoffset may be changed for that mobile IAB node, and the SIB may be updated as a result of this change. Also, in a non-mobile IAB node, when a mobile IAB node flows out of the cell of the non-mobile IAB node, the Qoffset may be restored to its original value, and the SIB may be updated again as a result of this change. Thus, in a non-mobile IAB node, the SIB may be updated each time a mobile IAB node flows into and out of the non-mobile IAB cell. Also, in a mobile IAB node, each time it flows into and out of the non-mobile IAB cell, it may adjust the Qoffset for the subordinate UE100 and update the SIB broadcast by the mobile IAB node.

[0075] Therefore, the objective of the first embodiment is to suppress the update frequency of the SIB.

[0076] Therefore, in the first embodiment, firstly, a relay node (e.g., IAB node 300) notifies the offset value for the mobile relay node (e.g., the offset value for the mobile IAB node). Secondly, a user device (e.g., UE100) executes an intra-frequency cell reselection procedure using the offset value for the mobile relay node.

[0077] In this way, the IAB node 300 broadcasts an offset value for the mobile IAB node, and the UE100 executes an intra-frequency cell reselection procedure using the offset value for the mobile IAB node. Therefore, the network side does not need to adjust the Qoffset for the mobile IAB node by using the offset value for the mobile IAB node. Thus, it is possible to suppress the frequency of SIB updates due to Qoffset adjustments.

[0078] A non-mobile IAB node is, for example, any node other than a mobile IAB node. A non-mobile IAB node may also be an intermediate IAB node. A non-mobile IAB node may also be a donor node 200 (or gNB200).

[0079] (Example of operation according to the first embodiment) Next, an example of operation according to the first embodiment will be described.

[0080] Figure 9 is a diagram illustrating an example of operation according to the first embodiment.

[0081] As shown in Figure 9, in step S10, the moving IAB cell 300-M broadcasts the moving IAB cell type information. However, the non-moving IAB cell 300-N does not broadcast the moving IAB cell type information.

[0082] In step S11, UE100 transitions to either the RRC idle state or the RRC inactive state.

[0083] In step S12, UE100 receives mobile IAB cell type information (and / or mobile speed information) broadcast from mobile IAB cell 300-M. UE100 may also receive this mobile IAB cell type information while initiating the intra-frequency cell reselection procedure and performing measurement on the serving cell and adjacent cells. UE100 can determine whether the serving cell and adjacent cells are mobile IAB nodes based on whether or not it has received this IAB cell type information.

[0084] In step S13, the moving IAB cell 300-M notifies the offset value for the moving IAB node. The offset value for the moving IAB node is, for example, an offset value used to adjust the RSRP (measured value) used in the ranking criterion R (Rs and Rn).

[0085] Firstly, the mobile IAB cell 300-M may broadcast the offset value for the mobile IAB node using SIB. Alternatively, the mobile IAB cell 300-M may transmit the offset value for the mobile IAB node using individual signaling (e.g., RRC release message).

[0086] Secondly, the mobile IAB cell 300-M may broadcast a mobile IAB node offset value such that the RSRP of the mobile IAB cell 300-M is higher than the RSRP of the non-mobile IAB cell 300-N. Such an offset value allows the network to keep the UE100 that has camped on to the mobile IAB cell 300-M camped on to the mobile IAB cell 300-M. Alternatively, the mobile IAB cell 300-M may broadcast a mobile IAB node offset value such that the RSRP of the mobile IAB cell 300-M is lower than the RSRP of the non-mobile IAB cell 300-N.

[0087] In step S14, the non-moving IAB cell 300-N notifies the offset value for the moving IAB node.

[0088] Firstly, non-moving IAB cell 300-N may also notify the offset value via SIB, similar to moving IAB cell 300-M, or the offset may be communicated via individual signaling (e.g., RRC release message). value You may send it.

[0089] Secondly, non-moving IAB cell 300-N may report an offset value for the moving IAB node such that the RSRP of moving IAB cell 300-M (adjacent cell) is lower than the RSRP of non-moving IAB cell 300-N. Alternatively, non-moving IAB cell 300-N may report an offset value for the moving IAB node such that the RSRP of moving IAB cell 300-M (adjacent cell) is higher than that of non-moving IAB cell 300-N.

[0090] The offset value for the mobile IAB node may notify different offset values depending on whether the cell of the IAB node 300 is the cell of the mobile IAB node (i.e., the mobile IAB cell 300-M) or the cell other than the mobile IAB node (i.e., the non-mobile IAB cell 300-N) as shown in steps S13 and S14.

[0091] In step S15, the UE 100 executes an intra-frequency cell reselection procedure. If the UE 100 starts to execute the procedure in step S12, in step S15, it may calculate the ranking criteria R (Rs and Rn) in the procedure. The UE 100 may use the offset value for the mobile IAB node as follows, for example.

[0092] First, it is the operation when the UE 100 camps on the non-mobile IAB cell 300-N (i.e., the mobile IAB cell 300-M is an adjacent cell). FIG. 10(A) shows an operation example in such a case.

[0093] That is, when the UE 100 camps on the non-mobile IAB cell 300-N, in the ranking criterion Rn for the adjacent cell, only for the mobile IAB cell 300-M (adjacent cell), the offset value for the mobile IAB node is subtracted from the RSRP measurement value (Q meas,n ) (or the offset value for the mobile IAB node with a negative offset value is added).

[0094] Thereby, for example, the network side can control to make it difficult for the UE 100 camping on the non-mobile IAB cell 300-N to reselect to the mobile IAB cell 300-M.

[0095] This operation may also be performed when UE100 is in a low-speed movement state ("Normal-mobility state" or "Medium-mobility state"). This is because UE100 is more likely to be in a low-speed movement state than when it is camped on to a moving IAB cell 300-M, since it is camped on to a non-moving IAB cell 300-N.

[0096] Thus, when UE100 is camped on to non-mobile IAB cell 300-N, it subtracts the offset value for the mobile IAB node from the RSRP for mobile IAB cell 300-M.

[0097] Secondly, consider the operation when UE100 is camped on to mobile IAB cell 300-M (i.e., mobile IAB cell 300-M is a serving cell). Figure 10(B) shows an example of operation in this case.

[0098] In other words, when UE100 is camped on to mobile IAB cell 300-M, the RSRP measurement value for the serving cell (Q) is used in the ranking criterion Rs for the serving cell. meas,s Add the offset value for the moving IAB node to (or subtract the offset value for the moving IAB node if it is a negative offset value).

[0099] This allows, for example, the network to control the UE100 that is camped on mobile IAB cell 300-M to continue re-selecting that mobile IAB cell 300-M.

[0100] Thus, when UE100 is camped on to mobile IAB cell 300-M, it adds a mobile IAB node offset value to the RSRP for that mobile IAB cell 300-M.

[0101] Furthermore, UE100 may perform this operation when it is camped on a moving IAB cell 300-M and the adjacent cell is not a moving IAB cell 300-M (i.e., the adjacent cell is a non-moving IAB cell 300-N). On the other hand, when UE100 is camped on a moving IAB cell 300-M and the adjacent cell is a moving IAB cell 300-M, it may perform the intra-frequency cell reselection procedure (i.e., calculate the ranking criterion R) without using the offset value for the moving IAB node. For example, in a scenario where the intra-frequency cell reselection procedure is performed between multiple moving IAB cells 300-M, it is easier for UE100 to reselect a moving IAB cell 300-M if the offset value for the moving IAB node is not used between moving IAB cells 300-M.

[0102] Furthermore, when the UE100 is camped on to the mobile IAB cell 300-M, the RSRP measurement value (Q) for the serving cell is obtained. meas,s Instead of adding the offset value for the moved IAB node to the ranking criterion Rn for adjacent cells, the RSRP measurement value (Q) for adjacent cells is used. meas,n You may subtract the offset value for the moving IAB node from (or add the offset value if the offset value for the moving IAB node is a negative offset value) from ( ).

[0103] Furthermore, the above-described operation when UE100 is camped on to the mobile IAB cell 300-M may also be performed when UE100 is in a high-mobility state. This is because UE100 moves (onboard) with the mobile IAB cell 300-M, making it more likely to be in a high-mobility state than when UE100 is camped on to the non-mobile IAB cell 300-N.

[0104] The gNB200 may configure how the offset for the moving IAB node should be applied to the UE100. In addition to the example above, the gNB200 may also configure the following: In the normal-mobility state, the gNB200 may apply the RSRP measurement (Q) only to the moving IAB cell 300-M (adjacent cell). meas,n ) may be set to subtract the offset value for the moving IAB node from (or add the offset value if the offset value for the moving IAB node is a negative offset value). Also, when the gNB200 is in a medium-mobility state or a high-mobility state, it may set the RSRP measurement value (Q) for the serving cell. meas,s ) may be configured to add an offset value for the moving IAB node. gNB200 may, instead of this addition, use the RSRP measurement value (Q) for the adjacent cell in the ranking criterion Rn for the adjacent cell. meas,n You may also set it to subtract the offset value for the moving IAB node from (or add the offset value if the offset value for the moving IAB node is a negative offset value).

[0105] (Another example of operation according to the first embodiment 1) In the first embodiment, the case in which the offset value for the moving IAB node is used in the ranking criterion R(Rs and Rs) of the intra-frequency cell reselection procedure was described, but the embodiment is not limited to this.

[0106] Firstly, the offset value for the moving IAB node may be used in the cell selection criterion S in the cell selection procedure. As described above, in the cell selection criterion S, the RSRP is compared with the minimum RSRP requirement level. The offset value for the moving IAB node can then be applied to the RSRP. Similar to the first embodiment, the cell selection criterion S may be determined by adding or subtracting the offset value for the moving IAB node depending on whether the cell to be measured is a moving IAB cell 300-M or a non-moving IAB cell 300-N.

[0107] Secondly, the offset value for the moving IAB node may be used in the measurement process for inter-frequency cell reselection. For example, in the comparison of the measured RSRP with a threshold value, the offset value for the moving IAB node can be applied to the RSRP. Similar to the first embodiment, the offset value for the moving IAB node can be added to or subtracted from the RSRP depending on whether the cell being measured is a moving IAB cell 300-M or a non-moving IAB cell 300-N.

[0108] (Another example of operation according to the first embodiment 2) In the first embodiment, the addition and subtraction of the offset value for the moving IAB node to the RSRP may be reversed. For example, if UE100 is camped on to a non-moving IAB cell 300-N, the RSRP measurement value (Q) is applied only to the moving IAB cell 300-M (adjacent cell). meas,n The offset value for the moving IAB node may be added to (or subtracted if the offset value for the moving IAB node is a negative offset value). Also, for example, if UE100 is camped on to moving IAB cell 300-M, the RSRP measurement value for the serving cell (Q meas,s You may subtract the offset value for the moving IAB node from (or add the offset value if the offset value for the moving IAB node is a negative offset value) from ( ).

[0109] [Second Embodiment] Next, a second embodiment will be described. In the second embodiment, the inter-frequency cell reselection procedure will be described.

[0110] For the inter-frequency cell reselection procedure in the moving IAB cell 300-M, the existing procedure using frequency priority can be used.

[0111] In other words, mobile IAB cell 300-M sets the frequency priority of the frequencies it uses higher than the frequency priority of the frequencies used by non-mobile IAB cell 300-N. By broadcasting this frequency priority, mobile IAB cell 300-M makes it less likely for UE100s camped on to mobile IAB cell 300-M to re-select non-mobile IAB cell 300-N. On the other hand, non-mobile IAB cell 300-N sets the frequency priority of the frequencies used by mobile IAB cell 300-M lower than the frequency priority of the frequencies it uses. By broadcasting this frequency priority, non-mobile IAB cell 300-N makes it easier for UE100s camped on to non-mobile IAB cell 300-N to re-select mobile IAB cell 300-M.

[0112] On the other hand, 3GPP specifies High Speed ​​Dedicated Networks (HSDNs) (for example, 3GPP TS 38.304 V17.2.0 (2022-09)). In HSDNs, there are cells called HSDN cells (high-speed dedicated network cells). HSDN cells broadcast HSDN cell information (hsdn-cell) indicating that they are HSDNs. A UE100 in a high-mobility state can consider an HSDN cell as the highest priority cell. Conversely, a UE100 not in a high-mobility state can consider an HSDN cell as the lowest priority cell. For example, a UE100 moving with a high-speed train can more easily re-select an HSDN cell installed along the tracks, prioritizing it over other cells. Therefore, HSDN can appropriately support communication to UEs in a high-mobility state.

[0113] Let's assume that HSDN is applied to the mobile IAB cell 300-M. In this case, the mobile IAB cell 300-M broadcasts HSDN cell information (hsdn-cell). When UE100 receives the HSDN cell information, if it is in a high-speed moving state, it can consider the mobile IAB cell as the highest-priority cell. On the other hand, when UE100 receives the HSDN cell information, if it is in a low-speed moving state, it can consider the mobile IAB cell as the lowest-priority cell.

[0114] However, if UE100 considers moving IAB cell 300-M as the lowest priority cell, even if it is in a low-speed moving state, UE100 may be unable to reselect moving IAB cell 300-M in the inter-frequency cell reselection procedure.

[0115] Therefore, in the second embodiment, firstly, the user device (e.g., UE100) receives from the cell HSDN cell information indicating that the cell is a High-Speed ​​Dedicated Network (HSDN) cell, and mobile relay node cell type information (e.g., mobile IAB cell type information) indicating that the cell is a mobile relay node cell. Secondly, when the user device is in a low-speed moving state, it assigns the cell the lowest priority. cell Without considering it as such, the inter-frequency cell reselection procedure is executed.

[0116] This 、H Upon receiving SDN cell information and mobile IAB cell type information, the UE100 will no longer consider the mobile IAB cell as the lowest priority cell, even if it is in a low-speed mobile state. Therefore, the UE100 can appropriately reselect the mobile IAB cell in the inter-frequency cell reselection procedure.

[0117] (Example of operation according to the second embodiment) Next, an example of operation according to the second embodiment will be described.

[0118] Figure 11 is a diagram illustrating an example of operation according to the second embodiment.

[0119] As shown in Figure 11, in step S20, the mobile IAB cell 300-M broadcasts HSDN cell information and mobile IAB cell type information. The mobile IAB cell 300-M may broadcast using SIB. The non-mobile IAB cell 300-N does not broadcast mobile IAB cell type information at least. The non-mobile IAB cell 300-N may broadcast HSDN cell information.

[0120] In step S21, UE100 transitions to either the RRC idle state or the RRC inactive state.

[0121] In step S22, UE100 receives HSDN cell information and mobile IAB cell type information (and / or mobile speed information) broadcast from mobile IAB cell 300-M. UE100 may also initiate the inter-frequency cell reselection procedure and receive HSDN cell information and mobile IAB cell type information during the measurement process. Based on whether or not mobile IAB cell type information is received, UE100 can determine whether each cell is a mobile IAB cell 300-M or a non-mobile IAB cell 300-N.

[0122] In step S23, the UE100, having received the HSDN cell information and the mobile IAB cell type information, performs predetermined processing. Specifically, the predetermined processing is as follows:

[0123] In other words, when in a high-mobility state, UE100 considers the cell that transmitted the HSDN cell information and mobile IAB cell type information as the highest-priority cell. On the other hand, when in a low-mobility state (normal-mobility state or medium-mobility state), UE100 does not consider the cell that transmitted the HSDN cell information and mobile IAB cell type information as the lowest-priority cell. In this case, UE100 uses the frequency priority provided by that cell (by an SIB or RRC release message, etc.) to execute the inter-frequency cell reselection procedure.

[0124] Furthermore, the UE100 may determine its movement status using a speed sensor or a GNSS (Global Navigation Satellite System) receiver, etc.

[0125] [Other embodiments] Each of the above-described operation flows can be performed not only independently, but also in combination of two or more operation flows. For example, some steps of one operation flow may be added to another operation flow, or some steps of one operation flow may be replaced with some steps of another operation flow. It is not necessary to execute all steps in each flow; only some steps may be executed.

[0126] In the embodiments and examples described above, an example in which the base station is an NR base station (gNB) was described, but the base station may also be an LTE base station (eNB) or a 6G base station. Furthermore, the base station may also be a relay node such as an IAB (Integrated Access and Backhaul) node. The base station may also be a DU of an IAB node. Furthermore, UE100 may be an MT (Mobile Termination) of an IAB node.

[0127] Furthermore, the term "network node" primarily refers to a base station, but may also refer to a core network device or a part of a base station (CU, DU, or RU).

[0128] A program may be provided that causes a computer to perform each of the processes performed by the UE100 or gNB200. The program may be recorded on a computer-readable medium. Using a computer-readable medium, it is possible to install the program on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transient recording medium. The non-transient recording medium is not particularly limited, but may be a recording medium such as a CD-ROM or DVD-ROM.

[0129] Alternatively, the circuits that perform each process carried out by the UE100 or gNB200 may be integrated, and at least a portion of the UE100 or gNB200 may be configured as a semiconductor integrated circuit (chipset, SoC: System on a chip).

[0130] The phrases “based on” and “depending on / in response to” used in this disclosure do not mean “based solely on” or “depending solely on” unless otherwise specified. “Based on” means both “based solely on” and “at least partially on.” Similarly, “depending on” means both “at least partially on” and “at least partially on.” The terms “include,” “comprise,” and variations thereof do not mean that only the listed items are included; they mean that only the listed items may be included, or that additional items may be included in addition to the listed items. Furthermore, the term “or” used in this disclosure is not intended to mean exclusive OR. Additionally, any reference to elements using designations such as “first,” “second,” etc., used in this disclosure does not generally limit the quantity or order of those elements. These designations may be used herein as a convenient way to distinguish between two or more elements. Therefore, references to the first and second elements do not imply that only two elements may be adopted therein, or that the first element must precede the second element in any way. In this disclosure, where articles are added by translation, such as a, an, and the in English, these articles shall be plural unless it is clearly indicated by the context that they are not.

[0131] Although one embodiment has been described in detail above with reference to the drawings, the specific configuration is not limited to that described above, and various design changes can be made without departing from the gist of the invention. Furthermore, each embodiment, each operation example, or each process can be combined as appropriate, within the bounds of consistency.

[0132] This application claims priority to U.S. Provisional Application No. 63 / 421712 (filed November 2, 2022), the entirety of which is incorporated into the specification of this application.

[0133] (First Appendix) (Note 1) A communication control method used in a cellular communication system, The relay node announces the offset value for the mobile relay node, The user device has the step of executing an intra-frequency cell reselection procedure using the offset value for the mobile relay node. Communication control method.

[0134] (Note 2) The notification step includes the step of notifying different offset values ​​for the mobile relay node depending on whether the relay node is a mobile relay node or a relay node other than the mobile relay node. The communication control method described in Appendix 1.

[0135] (Note 3) The steps to be performed include the user device changing how the offset value for the mobile relay node is applied depending on whether the serving cell and the adjacent cell are cells of a mobile relay node. The communication control method described in Appendix 1 or Appendix 2.

[0136] (Note 4) The aforementioned step of modification is: The user device, If camp-on occurs in a cell of a relay node other than the mobile relay node, the offset value for the mobile relay node is subtracted from the reference signal reception power for the cell of the mobile relay node. If the mobile relay node is camped on to a cell, the step includes adding an offset value for the mobile relay node to the reference signal received power for the cell of the mobile relay node. A communication control method as described in any of Appendix 1 to Appendix 3.

[0137] (Note 5) The addition step includes, in which the user device subtracts the offset value for the mobile relay node from the reference signal received power for the cells of relay nodes other than the mobile relay node, instead of adding the offset value for the mobile relay node. A communication control method as described in any of Appendix 1 to Appendix 4.

[0138] (Note 6) The aforementioned modification step, if the user device camps on to a cell of the mobile relay node and the adjacent cell is also a cell of the mobile relay node, executes the intra-frequency cell reselection procedure without using the mobile relay node offset value. A communication control method as described in any of Appendix 1 to Appendix 5.

[0139] (Note 7) The user device further includes the step of executing a cell reselection procedure using the offset value for the mobile relay node. A communication control method as described in any of Appendix 1 to Appendix 6.

[0140] (Note 8) The user device further includes the step of executing an inter-frequency cell reselection procedure using the offset value for the mobile relay node. A communication control method as described in any of Appendix 1 to Appendix 7.

[0141] (Note 9) The mobile relay node further comprises the step of broadcasting mobile relay node cell type information indicating that the node is the mobile relay node. A communication control method as described in any of Appendix 1 to Appendix 8.

[0142] (Note 10) A communication control method used in a cellular communication system, The user device receives from the cell HSDN cell information indicating that the cell is a High-Speed ​​Dedicated Network (HSDN) cell, and mobile relay node cell type information indicating that the cell is a mobile relay node cell. The user device, when in a low-speed movement state, has the step of executing an inter-frequency cell reselection procedure without considering the cell as the lowest priority cell. Communication control method.

[0143] (Note 11) The user device further includes the step of receiving the frequency priority of the frequencies used in the cell, The steps to be performed include the user device performing the inter-frequency cell reselection procedure using the frequency priority of the cell. Communication control method as described in any of Appendix 1 to Appendix 10

[0144] (Second Addendum) introduction The WID for mobile IAB was revised in RAN#97e, with the following objectives:

[0145] The detailed objectives of WI are as follows: Define migration / topology adaptation procedures that enable the mobility of IAB nodes, including the transfer of entire IAB nodes between donors (complete transfer). • Mobile IAB nodes can connect to fixed (intermediate) IAB nodes. Optimizations specific to scenarios where mobile IAB nodes connect to fixed (intermediate) IAB nodes, or where mobile IAB nodes connect directly to IAB donor DUs, have a lower priority. • Mobility of dual-connected IAB nodes will have a lower priority. • Enhanced mobility of IAB nodes and the UEs that serve them, including aspects related to group mobility. There is no optimization for targeting surrounding UEs. Note: The solution should avoid touching on topics that have already been discussed in Rel-17, or topics that have been excluded from Rel-17, except for enhancements specific to IAB node mobility. • Mitigation of interference through IAB node mobility, including avoidance of potential reference signal and control signal collisions (PCI, RACH, etc.). The following principles must be respected. - The relocated IAB node needs to be able to serve legacy UEs. - Solutions that provide optimization for mobile IAB may require extensions to the Rel-18 UE, provided that such extensions are backward compatible.

[0146] One of the main challenges of Rel-18 is how to efficiently perform the handover of multiple descendant UEs during the migration of a mobile IAB node. This note details the mobility enhancements for mobile IABs.

[0147] Discussion Strengthening UE Mobility UE handover procedure RAN2#119bis-e has reached the following agreement regarding the UE handover procedure:

[0148] If two logical DU cells use separate physical resources (i.e., different carriers, or orthogonal time and frequency resources for the same carrier, as supported in legacy L1), RAN2 focuses on the scenario where the UE perceives the two logical DU cells as different physical cells (e.g., different PCIs for the same carrier) during the full transition.

[0149] Based on the QCtdoc, the following options O1, O2, and O3 are considered. 1) Conditional delivery of messages via logical source IAB-DU (e.g., during MT migration), 2) Conditional execution by the UE based on broadcast instructions, such as service time SIB instructions or MT transition DCI instructions (including CHOs with new triggers). 3) Legacy CHO (implementation-specific behavior, e.g., using source cell power-down or target cell power-up to trigger the actual HO) RAN2 assumes that O1 and O3 above may function, and further consideration is needed if O2 (such as a new trigger) is required.

[0150] O1 is on hold for distribution and will function for UEs under Rel-15, therefore it is considered the baseline. O3, with its current conditional handover (CHO), will function for UEs under Rel-16 and beyond. Therefore, further consideration is needed regarding whether to enhance the CHO for Rel-18 based on, for example, O3.

[0151] Given that viable solutions such as O1 and O3 already exist, it's questionable whether further enhancements are truly necessary. On the other hand, at some point in the future, Rel-18 UEs are likely to become the majority in the network. In this case, if existing solutions have any shortcomings, it would be useful to implement some enhancements for Rel-18 and later UEs. If new solutions are discussed, one of the key points will be to avoid signaling storms caused by UE handovers, as pointed out in RAN2#119bis-e.

[0152] Proposal 1: RAN2 should discuss whether there are problems with the existing UE handover solutions, namely the delivery hold (O1) and CHO (O3).

[0153] In the case of O1, the RRC reconfiguration with synchronization is held by the mobile IAB node and delivered to the UE once the mobile IAB-MT has completed the transition to the target donor. The timing of sending the RRC reconfiguration message can be controlled by the mobile IAB node. Therefore, the timing of receiving the RRC Reconfiguration Complete message is controllable. This depends on how long the two cells (i.e., provided by the dual DU) are maintained, during which some DL load may occur on the source cell and some UL load on the target cell.

[0154] In the case of O3, RRC reconfiguration, including conditional reconfiguration, is pre-transmitted by the IAB donor via the mobile IAB node. This allows for pre-preparation of UE handover commands and enables the DL load to be distributed within the source cell in a timely manner. CHO, on the other hand, is performed when existing events (A3 / A5) are met. Since O3 relies on the radio state of the source / target cells (i.e., through control of transmit power), the source and target cells, in particular, are provided from physically quasi-positioned antennas.

[0155] Considering the above findings, O1 may require holding the source and target cells for extended periods to reduce DL / UL load. O3 may cause UL signaling storms in the target cell. Therefore, these issues should be resolved if a new solution is introduced; that is, the two cells (provided by dual DU) should be held for a minimum period to avoid signaling storms.

[0156] Proposal 2: Even if the source and target cells are retained for a minimum period during the migration of the moving IAB node, if the CHO is extended for Rel-18 UE, RAN2 should agree that the solution must avoid signaling storms at the DL (source cell) and UL (target cell).

[0157] Enhanced cell reselection functionality in UE RAN2#119bis-e agreed on the following confirmations, observations, and assumptions.

[0158] RAN2 verifies that the mobile IAB needs to work with the legacy UE. RAN2 has confirmed that if a UE camps on / connects to a mobile IAB cell for an extended period, the UE may perceive itself as being on the mobile IAB cell (i.e., the UE needs to know that this is such a cell). The timeframe requires further investigation.

[0159] RAN2 assumes the following for UEs operating in a mobile IAB cell: Scenario 1: From a network perspective, the principles for setting legacy parameters (including cell (re)selection, cell reservation, and access restrictions) for a moving IAB cell remain unchanged compared to a legacy IAB cell. Scenario 2: There will be no impact on the operation of legacy UE due to the specifications. Scenario 3: R18 of the moving IAB cell of Newly broadcast information (if agreed upon) will not restrict or control access for legacy UEs. Assumption 4: Non-extended UEs (including legacy UEs and R18 UEs that do not support extensions) will ignore newly broadcasted R18 information for moving IAB cells (if agreed upon). RAN2 assumption: In the case of broadcast information for a moving IAB cell. To support mobility in the idle / inactive mode of the Rel-18UE, a 1-bit mobile-IAB cell type indication (or mobile relay node cell type information) has been introduced (further consideration is needed regarding how to enable the UE to recognize that it is onboard). (ru). Further consideration is needed regarding how it will be used (it may be implementation-specific). RAN2 has not identified any changes to prevent surrounding UEs from accessing mobile IAB nodes from the perspective of mobile IAB WI, but it is possible that SA2 is working on a Rel-18 solution that may be applicable.

[0160] Two main scenarios and several sub-cases where UE behavior is expected are as follows: ●Scenario A: The moving IAB node is moving along with the camp UE (e.g., a train is in motion). Subcase A1: UE (e.g., inside a train) should remain on the mobile IAB node. Subcase A2: Surrounding UEs (such as outside the train) should not remain on the moving IAB node. ●Scenario B: The moving IAB node is stopped along with the camp UE (e.g., a train is stopped at a station). Subcase B1: UE (e.g., still on the train) should remain on the mobile IAB node. • Subcase B2:UE (e.g., getting off the train) requires re-selecting a fixed cell (such as a macro cell). Subcase B3: Surrounding UEs (e.g., boarding a train) need to re-select the moving IAB node. Subcase B4: Surrounding UEs (e.g., still inside the station) should remain within fixed cells.

[0161] In subcase A1, the UE moves with the mobile IAB node. Therefore, RSRP and RSRQ from the mobile IAB node are always stable and maintain sufficient quality. The cell reselection procedure is not triggered. More precisely, if the frequency priority of the mobile IAB node is higher than that of the outside cell, the UE may not be able to perform either intra-frequency or inter-frequency measurements. For example, the mobile IAB node broadcasts its frequency priority as "7" or broadcasts its cell as an HSDN cell.

[0162] One can think of a train as having multiple carriages, with mobile IAB nodes deployed in each carriage. Even if the UE moves between carriages, from the perspective of the UE inside the train, one of the mobile IAB node cells is always more stable than an external macrocell. Furthermore, in a typical case, it is assumed that the mobile IAB node cells are operating on the same frequency. In this case, existing in-frequency cell reselection, i.e., the R criterion, works appropriately.

[0163] Finding 1: A common configuration is for a moving IAB cell to broadcast either a serving frequency priority of "7" or an HSDN cell instruction to prevent cell reselection by a UE moving with the IAB cell.

[0164] In subcases B1 and B2, the AS has no way of knowing whether the user stays on the train or gets off. In this case, even if the mobile IAB node broadcasts some information, the UE cannot ultimately decide which cell to re-select, i.e., the mobile IAB node or the fixed macrocell. Therefore, which cell the UE re-selects is ultimately determined by the radio state and frequency priority. In other words, the mobile IAB node needs to revert the serving frequency priority set as Finding 1. Thus, the mobile IAB node needs to broadcast the serving frequency priority, for example, in the same way as the fixed macrocell layer. 、H Stop broadcasting SDN cell instructions.

[0165] Observation 2: If the UE and mobile IAB node stop working, the UE cannot decide whether or not to re-select the mobile IAB node unless it knows the user's intentions. In other words, it depends on the radio wave conditions.

[0166] Finding 3: A typical configuration may be one in which a stationary moving IAB cell reverts to the frequency priority or HSDN cell display used during movement (i.e., as in Finding 1).

[0167] However, considering the above observations, one drawback of the current mechanism is that the SIB of a moving IAB node needs to be changed according to its mobility status; that is, finding 1 if it is moving, and finding 3 if it is stationary. However, this may not be a significant problem to solve.

[0168] Finding 4: One drawback of the current mechanism is that the mobile IAB cell needs to change its mobility status, i.e., between Finding 1 and Finding 3, in its SIB.

[0169] In subcase A2, following the same logic as in Finding 1, the UE can continue camping in a fixed macrocell. That is, if RSRP / RSRQ from the macrocell is sufficiently good, the UE will not perform in-frequency measurements. Inter-frequency measurements will also not be performed if the macrocell frequency priority is higher than the mobile IAB node priority, or if the mobile IAB node broadcasts HSDN cell instructions (and the UE is not in a high-mobility state).

[0170] In subcases B3 and B4, cell reselection must be performed according to the wireless status for the same reasons as in Finding 2, and the same applies to the general configuration of a fixed mobile IAB node as in Finding 3.

[0171] However, subcases A2, B3, and B4 are desirable behaviors for the surrounding UEs. WID explicitly states that it does not perform optimizations targeting the surrounding UEs. In the case of subcase B3, after the UE boards the train, it becomes subcase B1 or B2, but the initial state of the UE is still that of a surrounding UE. Therefore, these subcases are outside the scope of Rel-18.

[0172] • Enhanced mobility of IAB nodes and the UEs that serve them, including aspects related to group mobility. There is no optimization for targeting surrounding UEs.

[0173] Finding 5: Optimization to target surrounding UEs is outside the scope of WI, but the same configurations as Findings 1 and 3 may be applicable.

[0174] In summary, the existing cell reselection mechanism, which is based on radio state and frequency prioritization, will continue to function properly. Therefore, no enhancements are needed for the UE to perform cell reselection.

[0175] HSDN may be useful in subcase A1, but it should be noted that it can be supported by mobile IAB nodes without changing the specifications.

[0176] Proposal 3: RAN2 should agree that no extension is needed for the UE to perform cell reselection with and from moving IAB nodes, meaning that there is no need to revert to the assumption made at the previous meeting regarding "1-bit moving IAB cell type representation".

[0177] Rel-18UE RACHless Handover RAN2#119e reached the following agreement: R2 assumes that a RACH-less procedure may be considered for onboard RRC_CONNECTEDUE, which is handed over along with the moving IAB node (depending on the assumption of UL synchronization).

[0178] In LTE, RACH-less handover is configured within MobilityControlInfo using applicable timing advance (TA) and uplink grant information as follows:

[0179] Regarding the TA value in RACH-less handover of a UE during IAB node migration, since the source and target cells are provided by the same "physical cell," the UE is expected to apply the latest TA value to access the target cell. The DU (but via dual "logical" DUs), i.e., the "physical" distance from the UE must be the same. Therefore, there is no need to explicitly set a TA value for the UE. On the other hand, if RACH-less handover is intended to be used in other scenarios, such as handover in mobile IAB-MT, a more general approach like an LTE configuration would be required.

[0180] Proposal 4: RAN2 should discuss whether, for UE RACH-less handovers, the UE implicitly applies the latest TA value or is explicitly set with an applicable TA value.

[0181] Since the UE needs to send RRC Reconfiguration Complete within the UL resources permitted by the target cell, UL permission information must be configured in the UE.

[0182] Proposal 5: RAN2 must agree that UL authorization information for UE RACH-less handovers should be set by the target IAB donor CU.

[0183] Since RACH-less handovers are indicated by the target IAB donor CU during the handover procedure, and considering the RRCIE structure of the NR, it can be assumed that the RACH-less configuration is included in reconfigurationWithSync within CellGroupConfig.

[0184] Proposal 6: RAN2 should agree to a reset with synchronization, meaning that a RACH-less handover is configured in the handover command.

[0185] One question is whether RACH-less handover can also be applied to conditional handover. Since RAN2#119e agrees that "R2 assumes that CHO or delayed RRC settings may be the baseline for group mobility," it is considered useful to support conditional RACH-less handover.

[0186] Proposal 7: RAN2 should discuss whether RACH-less handover can also be configured for conditional handover, i.e., conditional reconfiguration.

[0187] Enhancement of IAB-MT Mobility Movement to IAB Donor CU Display of IAB Node RAN3#117e reached the following agreement: The donor CU needs to be aware that the IAB node is "mobile".

[0188] Accordingly, RAN2#119bis-e agreed to the following baseline.

[0189] UE function signaling is a baseline that informs the CU that the MT is of the "Moving IAB" type. Further information is available regarding the initial Moving IAB indicator (e.g., message 5). Further consideration is needed. . Regarding the display of mobility status / mode, R2 should be noted that it can reuse the legacy mobility state report (e.g., mobileState-r16), and possibly the current location report from the UE as well.

[0190] In Rel-16 IAB, the IAB node indication is sent via Msg5 and is intended for the donor to use to select an AMF that supports IAB. Therefore, one of the key points is whether the donor needs to select an AMF that supports Mobile IAB up to RAN3, which determines whether they send the Mobile IAB Node Indication via Msg5.

[0191] In the email discussion, several companies noted that donor CUs can obtain real-time mobility status through existing measurement reports such as instant MDT. Such mobility status information is considered useful for predictive mobility control. The reporter clarified that instructions for the mobile IAB node are necessary for the donor to configure the mobile IAB node with the appropriate measurement configuration. However, early notification is not justified because it is not a major issue if the donor CU configures the mobile IAB node after receiving UE function signaling.

[0192] Therefore, whether an initial IAB movement instruction is required depends on RAN3.

[0193] Finding 6: Whether an initial mobile IAB instruction is required in Msg5 depends on RAN3, for example, whether the donor CU needs to select an AMF that supports mobile IAB.

[0194] Access restrictions for mobile IAB nodes The WID states that the mobile IAB node will only serve the UE. - A mobile IAB node must not have any descendant IAB nodes. In other words, it should only serve UEs.

[0195] To ensure the requirements are met, RAN2#119e agreed to the following: The method of not broadcasting the "iab-Support" message is sufficient to prevent other IAB nodes from accessing the mobile IAB (and does not further affect the specifications).

[0196] However, it could be argued that the agreement was reached without sufficient discussion. In particular, the part that says "(no impact on further specifications)" raises questions about whether it is truly sufficient to leave it to the implementation. Since WID clearly requires that mobile IAB nodes cannot access other mobile IAB nodes, it is thought that this premise needs to be clarified in the specification to avoid confusion in the implementation of mobile IABs. Therefore, it is recommended that the Stage 2 specification either obtain the above agreement or clearly state that "in this release, mobile IAB nodes cannot access other mobile IAB nodes."

[0197] Proposal 8: RAN2 should agree to incorporate the Stage 2 specification that if an IAB node is to function as a mobile IAB node in this release, IAB support IE should not be configured in the SIB.

[0198] Another restriction was discussed in RAN2#119bis-e, and it was determined that further consideration is needed, as follows: Further consideration is needed regarding whether fixed networks should introduce a broadcasting system indicating that they "support mobile IAB" (targeting mobile IABMT).

[0199] Several companies have pointed out that "whether instructions from the network to the mobile IAB node are needed may depend on whether the mobile IAB node can / should camp on / connect to a regular IAB-enabled cell." Assuming that traditional IAB donors exist in the network, there are three releases of IAB, and different releases support different migration mechanisms. Specifically, Rel-16 is intra-CU topology adaptation, Rel-17 is inter-CU topology adaptation with partial migration, and Rel-18 is inter-CU migration with full migration.

[0200] Therefore, technically, a mobile IAB node can connect to a Rel-16 donor if it is only moving nearby (i.e., within a cell belonging to the same donor CU), but the mobile IAB node needs to connect to a Rel-17 or Rel-18 donor. If the Rel-18 donor moves far away (i.e., between cells belonging to different donor CUs), in other words, the former mobile IAB node can be considered simply a stationary IAB node from a functional standpoint.

[0201] Finding 7: A mobile IAB node can connect to a Rel-16 donor if it is only moving nearby, but if it is moving far away, the mobile IAB node needs to connect to a Rel-17 or Rel-18 donor.

[0202] In this sense, some kind of "supported mobile IAB" information needs to be broadcast by the parent node, but it is questionable whether this can determine which cells a mobile IAB node can connect to. Based on such a 1-bit instruction, for example, the instruction could be associated with the area the mobile IAB node can move to. However, this may also mean that the mobile IAB node needs to know the area it moves to (or whether it is considered a fixed IAB node), for example, through the OAM configuration. Furthermore, it is worth considering whether there are other cases in which a mobile IAB node can connect to a parent node that does not broadcast an indication. For example, a case in which the mobile IAB node cannot find a parent node that broadcasts an indication. Therefore, RAN2 should discuss in detail what that instruction means.

[0203] Proposal 9: RAN2 should agree to introduce some kind of “support mobile IAB” indication. Further consideration is needed as to whether it is simply a 1-bit instruction and / or whether there is a condition that the mobile IAB node can access a parent node that does not broadcast the instruction.

Claims

1. A communication control method used in a cellular communication system, The relay node broadcasts the offset value for the mobile relay node, A user device in a Radio Resource Control (RRC) inactive or RRC idle state executes an intra-frequency cell reselection procedure using the offset value for the mobile relay node. Communication control method.

2. The notification includes notifying different offset values ​​for the mobile relay node depending on whether the relay node is a mobile relay node or a relay node other than the mobile relay node. The communication control method according to claim 1.

3. The above action includes the user device changing how it applies the offset value for the mobile relay node depending on whether the serving cell and the adjacent cell are cells of a mobile relay node. The communication control method according to claim 1.

4. The aforementioned changes are, The user device, If camp-on occurs in a cell of a relay node other than the mobile relay node, the offset value for the mobile relay node is subtracted from the reference signal reception power for the cell of the mobile relay node. If camped on to a cell of the mobile relay node, this includes adding the mobile relay node offset value to the reference signal received power for the cell of the mobile relay node. The communication control method according to claim 3.

5. In the addition described above, the user device may, instead of adding the offset value for the mobile relay node, subtract the offset value for the mobile relay node from the reference signal received power for the cells of the relay nodes other than the mobile relay node. The communication control method according to claim 4.

6. The above modification means that if the user device camps on to a cell of the mobile relay node and the adjacent cell is also a cell of the mobile relay node, the intra-frequency cell reselection procedure is executed without using the mobile relay node offset value. The communication control method according to claim 3.

7. The user device further includes executing a cell reselection procedure using the offset value for the mobile relay node. The communication control method according to claim 1.

8. The user device further includes executing an inter-frequency cell reselection procedure using the offset value for the mobile relay node. The communication control method according to claim 1.

9. The mobile relay node further includes broadcasting mobile relay node cell type information indicating that the node is the aforementioned mobile relay node. The communication control method according to claim 1.

10. A user device in which Radio Resource Control (RRC) is inactive or idle, A receiving unit that receives the offset value for the mobile relay node notified by the relay node, The system includes a control unit that executes an intra-frequency cell reselection procedure using the offset value for the mobile relay node. User device.

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