Control device, control method, and program

Abstract

To control a communication path according to a communication state of a connectable IAB node.SOLUTION: A control unit of an integrated access and backhaul (IAB) network acquires a plurality of types of dynamic information indicating a communication state of an IAB node connectable to a predetermined IAB node, the IAB node for relaying the connection between an IAB donor of the IAB network and the predetermined IAB node, selects at least one type of dynamic information from the acquired plurality of types of dynamic information based on a slice type that should be supported by the predetermined IAB node, and controls a communication path between the predetermined IAB node and the IAB donor according to the selected at least one type of dynamic information.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a control device, a control method, and a program. [Background technology]

[0002] The 3GPP (3rd Generation Partnership Project) is currently standardizing IAB (Integrated Access and Backhaul) as a communication technology for backhaul. The IAB technology utilizes millimeter-wave wireless communication, such as the 28 GHz band, which is used for access communication between a base station and user equipment (UE), as backhaul communication (Patent Document 1).

[0003] In backhaul communications using IAB technology, studies have been conducted to restore and improve the communication situation by switching communication paths in preparation for deterioration of the wireless environment or occurrence of a failure between an IAB donor equivalent to a base station and an IAB node equivalent to a relay station (Patent Document 2). Patent Document 2 discloses that when the communication environment of an already established communication path deteriorates, an IAB node that supports network slicing is selected to switch the communication path. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2019-534625 [Patent Document 2] International Publication No. 2020 / 031269 Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 2, the IAB donor selects a path based only on the slice type requested by the UE. In such a case, the requested slice type may not be supported due to an increase in the number of hops caused by an update to the network topology, an increase in the processing load of the IAB node, or a change in the number of connected terminals.

[0006] In view of the above problems, an object of the present invention is to control communication paths in accordance with the communication status of connectable IAB nodes. [Means for solving the problem]

[0007] In order to solve the above problems, a control device according to the present invention is a control device for an IAB (Integrated Access and Backhaul) network, an IAB node for relaying a connection between an IAB donor of the IAB network and a predetermined IAB node, and acquiring means for acquiring dynamic information indicating a communication status of the predetermined IAB node and an IAB node connectable to the predetermined IAB node; a path control means for selecting at least one type of information included in the dynamic information acquired by the acquisition means and corresponding to a slice type to be supported by the specified IAB node, and for controlling a communication path between the specified IAB node and the IAB donor according to the selected information; a first receiving means for receiving a Radio Resource Control (RRC) signal including a request for re-establishment of a communication path, a notification of a radio link failure, and flow control feedback from the predetermined IAB node; Equipped with 、 When the first receiving means receives the RRC signals from a plurality of IAB nodes within a predetermined period, the path control means controls the communication path of an IAB node with a large number of connected user devices by giving priority to the communication path. . [Effects of the Invention]

[0008] According to the present invention, it is possible to control a communication path depending on the communication status of a connectable IAB node. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 illustrates an example of a backhaul communication system according to an embodiment of the present invention. [Figure 2]Hardware functional block diagram of IAB donor 101 according to this embodiment [Figure 3] Software functional block diagram of IAB donor 101 according to this embodiment [Figure 4] A flowchart showing a method for determining a new connection destination according to the present embodiment. [Figure 5] 1 is a flowchart showing a method for determining a new connection destination when a slice request of URLLC is made according to the first embodiment. [Figure 6] FIG. 10 is a diagram showing an example of a connection candidate list in an IAB node 105 according to the first embodiment. [Figure 7] FIG. 1 shows an example of an NSSAI list of an IAB donor 101 and each IAB node 102 to 106 according to this embodiment. [Figure 8] FIG. 10 is a diagram showing an example of a dynamic information list managed by an IAB donor 101 according to the present embodiment. [Figure 9] FIG. 1 is a sequence diagram showing connection establishment of a destination path according to the first embodiment. [Figure 10] FIG. 1 is a diagram showing a topology after a new communication path is connected according to the first embodiment; [Figure 11] 10 is a flowchart showing a method for determining a new connection destination when an eMBB requests a slice according to a second embodiment. [Figure 12] FIG. 10 is a diagram showing a topology after a new communication path is connected according to the second embodiment. [Figure 13] 10 is a flowchart showing a method for determining a new connection destination when a slice request is made by MIot according to the third embodiment. [Figure 14] FIG. 10 is a diagram showing a topology after a new communication path is connected according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the present invention, and not all of the combinations of features described in the embodiments are necessarily essential to the solution of the present invention.

[0011] In backhaul communications using IAB technology, relay devices called IAB nodes relay communications from IAB donors, which are equivalent to conventional base stations. IAB nodes form communication links with multiple other IAB nodes, forming a network tree starting from the IAB donor, enabling the IAB donor to expand the area to which it can provide network access.

[0012] In IAB technology, communication between IAB donors and IAB nodes, and between IAB nodes, is controlled via the Backhaul Adaptation Protocol (BAP), which is primarily defined as a protocol for routing data between multiple IAB nodes.

[0013] In addition, in IAB technology, studies are underway to introduce the concept of network slicing, which virtually provides network slices corresponding to different conditions on a common network in response to the reception of a slice request signal from a connecting user equipment (UE).

[0014] The types of network slices already specified are enhanced Mobile Broadband (eMBB), low latency (URLLC), and simultaneous multiple connections (MIot). For example, a system is under study in which a base station broadcasts the network slices it provides, allowing the UE to select one based on its purpose, or the UE requests a network slice and the base station responds. Here, eMBB stands for enhanced Mobile Broadband. URLLC stands for Ultra-Reliable and Low Latency Communications, and MIoT stands for Massive Internet of Things.

[0015] For example, eMBB requires high-throughput communication, so IAB nodes supporting eMBB may be required to reserve uplink or downlink data buffers. Also, URLLC requires low-latency communication, so IAB nodes requesting URLLC may be required to reduce the number of hops to an IAB donor. Also, MIoT requires a large number of UEs to be connected, so it may be necessary to ensure that the total number of UEs in a communication path does not exceed a threshold.

[0016] In backhaul communications using IAB technology, there are cases where an IAB node cannot meet the slice requirements due to insufficient capabilities of the IAB donor or IAB node connected to the higher level, or due to a deterioration in communication conditions. To address this issue, a technology has been proposed that identifies IAB nodes that do not have the functionality to support the requested slice type and selects an IAB node that meets the requested slice type as the migration destination, thereby enabling appropriate path switching and multipath connection.

[0017] However, even if an IAB node forming a communication path satisfies the slice type requested by the UE, it may not satisfy the above-mentioned slice requirements due to dynamically changing communication conditions.

[0018] In the following embodiment, a communication system is described that acquires dynamic information regarding dynamically changing communication conditions, selects information from the dynamic information based on the requested slice type, and controls the communication path to set a communication path that can support the slice type.

[0019] <Embodiment 1> 1 is a diagram showing an example of a wireless communication system 100 according to this embodiment. The wireless communication system 100 includes an IAB donor 101 that provides a connection to a CN (Core Network) 130, and a backhaul network (IAB network) that includes IAB nodes 102 to 106. Here, the CN is responsible for various processes such as authenticating terminals UEs 110 to 120, controlling packet forwarding, and establishing communication paths.

[0020] The IAB donor 101 comprehensively controls each of the IAB nodes 102 to 106 and forms the coverage area of ​​the local station. It is also assumed that the IAB donor 101 determines and assigns the type of network slice that each of the IAB nodes 102 to 106 can support. That is, the IAB donor 101 manages information on the type of network slice supported by each of the IAB nodes 102 to 106. In this embodiment, it is assumed that the IAB donor 101 manages slice information supported by each of the IAB nodes 102 to 106 as a list of NSSAI (Network Slice Selection Assistance Information). It is also assumed that if there is a change in the slices that the IAB nodes 102 to 106 can support, the IAB donor 101 is notified by a BAP control message.

[0021] A BAP control message is a message exchanged in accordance with the format of a BAP control PDU (Protocol Data Unit). Control information may be transmitted using the PDU type field, or other reserved fields in the BAP control message may be used.

[0022] Assume that UEs 110 to 120 are executing applications that utilize desired slices provided by each IAB node 102 to 106. For example, UE 118 is executing an application that requests an eMBB slice, and UE 119 is executing an application that requests URLLC. For example, eMBB requires a communication path with higher throughput (large capacity) than URLLC, and URLLC requires a communication path with lower communication delay and lower packet loss rate than eMBB, and each slice has different requirements (slice requirements).

[0023] Here, assume that wireless quality deteriorates and a link failure occurs in the wireless section between IAB node 104 and IAB node 105 in wireless communication system 100. In this case, only eMBB as a specific slice no longer satisfies the requirements in IAB node 105, and an error may occur in the application executed by UE 118 among the UEs connected to IAB node 105.

[0024] In such a case, the IAB node 105 detects that it no longer satisfies the eMBB slice requirement (slice requirement non-achievement) and notifies the IAB donor 101 of a change in the NSSAI by a BAP control message. Here, the IAB node 105 may detect that the slice requirement has not been met by the IAB donor 101 or the IAB node 105 receiving a control message indicating an eMBB slice request from the UE 118. Alternatively, the IAB donor 101 or the IAB node 105 may determine that the slice requirement has not been met based on the signal quality from the IAB node 104 that is periodically measured by RRM (Radio Resource Management).

[0025] In order to restore communication with the IAB node 105 where the link failure occurred, the IAB node 104 may establish a new communication path from the IAB node 104 to the IAB node 105 via the IAB node 103, and continue the communication. In such a case, the IAB node 105 may be able to continue to satisfy the eMBB slice request from the UE 118. However, because the number of hops increases due to the switching of the communication path, there may be cases where the slice requirements cannot be met, such as the low latency function cannot be performed for the URLLC slice requested by the UE 119.

[0026] In such a case, in order to rescue an IAB node that can no longer meet the slice requirements requested by the UE, the IAB donor 101 determines the IAB node to connect to in order to form a new communication path and notifies the relevant IAB node.

[0027] 2 is a hardware functional block diagram of the IAB donor 101 according to this embodiment. The IAB donor 101 includes a control unit 201, a storage unit 202, a wireless communication unit 203, and an antenna control unit 204. Here, the hardware will be described assuming the IAB donor 101, but the IAB nodes 102 to 106 are also assumed to have a similar configuration.

[0028] The control unit 201 controls the entire IAB donor 101 by executing a control program stored in the storage unit 202. The control unit 201 includes a processor and a memory. The storage unit 202 stores the control program executed by the control unit 201, as well as various information such as the identifier of a cell (cell ID) provided by the IAB donor 101, information about UEs connecting to the IAB donor 101 or an IAB node, and routing information of the IAB node. The various operations described below are performed by the control unit 201 executing the control program stored in the storage unit 202.

[0029] The wireless communication unit 203 is a communication unit equipped with a wireless communication circuit for performing cellular network communication such as LTE or 5G conforming to the 3GPP standard. The wireless communication unit 203 is also capable of measuring communication conditions with each of the IAB nodes 102-106 and the UEs 110-120 in accordance with RRM, and is capable of notifying the IAB donor 101 and the IAB nodes 102-106 by RRC. RRC stands for Radio Resource Control. RRC has functions such as connection establishment, admission control, RRC state management, and reporting of neighboring cell information and access restrictions in the IAB nodes 102-106 and the UEs 110-120. The RRC function RRM is also capable of acquiring communication conditions such as reference signal reception power and reference signal reception quality of neighboring cells.

[0030] The antenna control unit 204 controls the antenna used for wireless communication performed by the wireless communication unit 203 .

[0031] 3 is a software functional block diagram of the IAB donor 101 according to this embodiment. The software functional block shown in FIG. 3 is stored in the storage unit 202 and is realized by being executed by the control unit 201. The software functional block is composed of a signal transmission unit 301, a signal reception unit 302, a data storage unit 303, a connection control unit 304, a dynamic information update detection unit 305, a connection candidate list collection unit 306, a slice management unit 307, a communication path selection unit 308, and a dynamic information management unit 309.

[0032] The signal transmitting unit 301 and the signal receiving unit 302 control the wireless communication unit 203 via the control unit 201, and perform cellular network communication such as LTE or 5G that complies with the 3GPP standard between the IAB nodes 102 to 106 and the UEs 110 to 120.

[0033] The data storage unit 303 controls and manages the storage unit 202, which is the entity, and stores and holds the software itself, routing information of the IAB nodes 102 to 106, information on the UEs 110 to 120, etc. Furthermore, the connection control unit 304 controls the antenna control unit 204 via the control unit 201 during wireless communication.

[0034] The dynamic information update detection unit 305 receives RRC signals including a request for re-establishment of a communication path, a change of a connection path, a notification of a radio link failure, flow control feedback, and a handover completion notification notified from the IAB nodes 102 to 106, and notifies the communication path selection unit 308. The dynamic information update detection unit 305 is also a path control unit that updates the dynamic information of the IAB nodes managed by the dynamic information management unit 309.

[0035] The connection candidate list collection unit 306 collects and manages the connection candidate lists in each of the IAB nodes 102 to 106. The slice management unit 307 stores and manages the NSSAI lists supported by each of the IAB nodes 102 to 106, which are acquired from the IAB nodes 102 to 106 via BAP control messages.

[0036] In response to notification from the dynamic information update detection unit 305, the communication path selection unit 308 references the connection candidate list of the IAB node 105, slice information of its own station and each of the IAB nodes 102 to 104, and the dynamic information management unit 309 to determine a new connection destination capable of restoring the IAB node 105. Being able to restore the IAB node 105 here means that a path can be established that can satisfy the slice requirements requested by the UE directly connected to the IAB node 105. The communication path selection unit 308 notifies the IAB node 105 of the determined new connection destination by an RRC control message. The RRC control message here is a message that conforms to the PDU format specified by RRC and is realized using any field that indicates a function provided by RRC. The notification to the IAB node 105 by an RRC control message may be a neighbor cell list (NCL) containing only the new connection destination.

[0037] The update of dynamic information in the IAB node 105 may be detected by receiving a URLLC slice request signal from the UE 119, or may be determined by the local station based on the signal quality from the IAB node 102 measured periodically by RRM.

[0038] The dynamic information management unit 309 manages, as dynamic information, the number of hops, free buffer capacity, and total number of UEs on the path in each IAB node 102-106 managed by the IAB donor 101. That is, the dynamic information includes multiple types of information that change depending on the communication status of each IAB node and is used by the IAB donor 101 to determine the communication status of each IAB node. Furthermore, as described below, the dynamic information may include the processing delay time of the IAB node, the number of UEs connected to the IAB node, the maximum subframe size, the proportion of uplink (UL) transmission in the TDD pattern, and the minimum value of radio wave intensity within a predetermined time. In this case, based on the above-described information received from each IAB node, the dynamic information management unit 309 may use the total processing delay time and the total number of connected UEs on the communication path from the IAB donor to the specified IAB node as the dynamic information of the specified IAB node. Alternatively, based on the above-mentioned information, the dynamic information management unit 309 may set predetermined statistical quantities, such as the minimum maximum subframe size of each IAB node on the communication path, the minimum UL transmission ratio, and the minimum signal strength, as the dynamic information of the specified IAB node.

[0039] Here, the software has been described assuming the IAB donor 101. However, the configurations other than the dynamic information update detection unit 305, the connection candidate list collection unit 306, the slice management unit 307, the communication path selection unit 308, and the dynamic information management unit 309 are assumed to be the same for the IAB nodes 102 to 106.

[0040] 4 is a flowchart showing an example of a new path determination process according to this embodiment. The flowchart shown in FIG.

[0041] In S400, the IAB donor 101 receives notification by an RRC control message that determines the network topology, and then calculates the number of hops for each IAB node and the total number of UEs. The IAB donor 101 also stores and manages the free buffer capacity by receiving a BSR (Buffer Status Report) notified by each IAB node when a data message is received or when a parent node polls.

[0042] In S401, the IAB donor 101 checks whether there is an IAB node with an updated hop count. If there is an updated IAB node (Yes in S401), the IAB donor 101 proceeds to S405 and checks whether the requested slice is URLLC. If the requested slice is URLLC, the IAB donor 101 proceeds to S408, determines to refer to the hop count from the dynamic information, and proceeds to S411, where the path is updated. If the requested slice is not URLLC, the IAB donor 101 proceeds to S412 and notifies the UE that the requested slice does not satisfy URLLC.

[0043] If there is no IAB node with an updated hop count in S401 (No in S401), the IAB donor 101 checks in S402 whether there is a congestion notification from each IAB node via flow control feedback. If there is a congestion notification in S402 (Yes in S402), the IAB donor 101 determines whether the slice requested by the IAB node where congestion occurred is eMBB. If the requested slice is eMBB (Yes in S406), the IAB donor 101 proceeds to S409, determines to refer to the free buffer capacity from the dynamic information, and determines to update the path (S411). If the requested slice is not eMBB (No in S406), the IAB donor 101 proceeds to S412, and notifies the UE that the requested slice does not satisfy eMBB.

[0044] If no IAB node that notified congestion is detected (No in S402), the IAB donor 101 proceeds to S403 and detects the IAB node with the maximum number of UEs connected per IAB node (256 UEs per base station). If an IAB node with the maximum number of UEs is found in S403, it is confirmed whether the requested slice is MIot (S407). If the requested slice is MIot (Yes in S407), the IAB donor 101 proceeds to S410, determines to refer to the total number of UEs from the dynamic information, and updates the path (S411). If the requested slice is not MIot (No in S407), the IAB donor 101 proceeds to S412 and notifies the UE that the requested slice does not satisfy MIot. In addition, the type of network slice may be set to C-V2X (Cellular-Vehicle to Everything) or other slice types other than high-speed, high-capacity (eMBB), low latency (URLLC), and simultaneous multiple connections (MIot).

[0045] 5 is a flowchart showing a method for determining a new connection destination path when a URLLC slice request is made in embodiment 1. The flowchart shown in FIG.

[0046] In S500, the dynamic information update detection unit 305 detects that the number of hops, which is dynamic information of the URLLC at the IAB node 105, has been updated based on updates to the network topology and congestion level, and the communication path selection unit 308 receives this.

[0047] In S501, the connection candidate list collection unit 306 collects a list of connection candidate IAB nodes that can be connected from the IAB node 105 (connection candidate list) using an RRC control message. In S502, the IAB node 104, which is (was) the parent node of the IAB node 105 at the start of the process, is set as the IAB node of the provisional connection destination. A parent node is a node located upstream of a specified node on the communication path.

[0048] The processes from S503 to S508 and S511 to S513 are repeated for all IAB nodes 102 to 103 and 106 in the connection candidate list of the IAB node 105 for which an update of the dynamic information has been detected.

[0049] In S504, the NSSAI list of the connection candidate IAB node n managed by the slice management unit 307 is referenced to determine whether the connection candidate IAB node n satisfies the URLLC slice requirements. If the requirements are met (Yes in S504), information regarding the number of hops is selected from the dynamic information in S505. If the requirements are not met (No in S504), the process proceeds to S513, the status quo is maintained for the IAB node, and the process is repeated for the next connection candidate IAB node n. Here, maintaining the status quo means that the communication path for the connection candidate IAB node n is not changed, i.e., the provisional connection destination IAB node is not changed.

[0050] In S506, the number of hops to the IAB donor 101 is compared between the provisional destination IAB node and the connection candidate IAB node. If the number of hops of the provisional destination IAB node is greater than the number of hops of the connection candidate IAB node (Yes in S506), the IAB donor 101 proceeds to S507 and determines the connection candidate IAB node with the fewer hops as the provisional destination IAB node. If the number of hops of the provisional destination node is less than or equal to the number of hops of the connection candidate node in S506 (No in S506), the IAB donor 101 proceeds to S511 and determines whether the number of hops of the provisional destination node is equal to the number of hops of the connection candidate node. If the number of hops of the provisional destination node is equal to the number of hops of the connection candidate node (Yes in S511), the IAB donor 101 compares the delay time T from the dynamic information. Here, the value of T is a parameter of the communication path used to determine which path can reduce communication delay more when the tentative candidate node and the connection candidate node have the same number of hops. The value of T may be determined by referring to the following values:

[0051] (1) Node processing delay (total for all IAB nodes on the path) (2) Total number of UEs (total of all IAB nodes on the path) (3) Subframe size (maximum value at each IAB node on the path) (4) UL ratio of TDD pattern (minimum value at each IAB node on the path) (5) Signal strength (minimum value at each IAB node on the path) If the number of hops of the provisional destination node is smaller than the number of hops of the connection candidate IAB node in S511, the IAB donor 101 proceeds to S513 and maintains the status quo for the IAB node. In S514, the IAB donor 101 references the next IAB node.

[0052] After repeating this process for all connection candidate IAB nodes n, in S509 the provisional destination IAB node is determined as the destination IAB node, and an RRC control message is transmitted to the IAB node 105 requesting connection to the destination IAB node.

[0053] The IAB node 105, which receives notification of the destination IAB node 103 with the minimum number of hops from the IAB donor 101, connects to the new destination IAB node 103. This enables communication using a path with the minimum number of hops.

[0054] 6 shows an example of a connection candidate list in the IAB node 105 of embodiment 1. The connection candidate list 601 may be transmitted as neighboring cell information from each of the IAB nodes 102 to 103, 106 via an RRC control message based on the RRM measurement results of the IAB node 105, and may be collected and managed by the connection candidate list collection unit 306 of the IAB donor 101.

[0055] Alternatively, the IAB donor 101 may collect the RRM measurement results of each IAB node 102-105 via an RRC control message and generate a list, for example, in descending order of signal strength. Also, the IAB donor 101 may collect and use the NCL as a connection candidate list for each IAB node 102-106.

[0056] In the connection candidate list 601, IAB node 104 is the IAB node with the strongest radio wave among the connection destinations of IAB node 105, but if the connection is cut off due to radio interference, the IAB node with the next strongest radio wave after IAB node 104 is IAB node 103. Note that in the connection candidate list shown in Fig. 6, radio wave strength is shown as being classified into classes such as unacceptable, fair, and good, but it may also be a numerical value indicating the radio wave strength.

[0057] Next, referring to FIG. 7, an example of the NSSAI list of each IAB node 102 to 106 will be shown, and the process in which the IAB donor 101 determines whether the IAB node 103 satisfies the slice requirements in the processes of S405 to S407 will be described.

[0058] FIG. 7 shows an example of the NSSAI list of the IAB donor 101 and each of the IAB nodes 102 to 106 in the first embodiment.

[0059] NSSAI lists 701 to 705 are examples of slice correspondence information for IAB nodes 102 to 106 managed by slice management unit 307. Here, 704 is a list for IAB node 105 in which an update of the number of hops was detected in S401.

[0060] The value written in the NSSAI indicates the Slice Service Type (SST), which is the slice type that can be supported, with eMBB being associated with "1", URLLC being associated with "2", and MIot being associated with "3". In the NSSAI lists 700 to 705, the IAB donor 101 supports all slice types, eMBB, URLLC, and MIot. In addition, the IAB nodes 102 to 104 support the SST of eMBB and URLLC, while the IAB node 105 is affected by a communication link failure and is unable to provide eMBB, so it only supports the SST of URLLC. The IAB node 106 supports the SST of URLLC and MIot.

[0061] 5, the example has been described assuming that connection is made to the IAB node among the connection candidate IAB nodes that has the smallest number of hops from the IAB donor 101. However, for IAB nodes whose number of hops is equal to or less than a predetermined threshold (first threshold), comparison may be made using the delay time T described above. This makes it possible to select a communication path with a smaller communication delay even when factors other than the number of hops have a large impact on communication delay.

[0062] Fig. 8 shows an example of a dynamic information list of each IAB node 102 to 106 managed by the IAB donor 101 according to this embodiment. The dynamic information list shown in Fig. 8 is updated when the IAB donor 101 receives a notification of path switching, BSR, etc. from each IAB node 102 to 106, and is managed by the dynamic information management unit 309.

[0063] In Fig. 1, due to the influence of a communication link failure between IAB node 104 and IAB node 105, a new path is formed by connecting IAB node 104 to IAB node 105 via IAB node 103. Due to this network topology update, the number of hops, which is the dynamic information of IAB node 105 in Fig. 8, is updated from 3 to 4, and this update is detected in S401 in Fig. 4.

[0064] Here, the IAB node 103, which is the candidate node for connection, is the IAB node with the minimum number of hops that can support the URLLC slice request in S509, and is therefore selected as the connection destination for forming a new communication path with the IAB node 105. Although the IAB node 105 appears to be able to support URLLC in the NSSAI due to path switching caused by a communication link failure, it may not be able to execute the URLLC function due to the increased delay time caused by the increased number of hops. In such a case, the IAB donor 101 according to this embodiment establishes a connection of a new communication path to the IAB node 105 that needs to be rescued, i.e., the IAB node 105 that cannot meet the requested support.

[0065] Here, the IAB donor 101 detects that the hop count of the IAB node 103 is 1 from the hop count information of the IAB node 103 shown in Fig. 8. Then, since the path connecting the current IAB donor 101 to the IAB node 105 via the IAB node 103 has the smallest number of hops, the IAB donor 101 controls the IAB nodes 103 and 105 to use this communication path and sets up a communication path. This makes it possible to set up a communication path that meets the slice type requirements requested by the UE connecting to the IAB node 105.

[0066] 9 is a sequence diagram showing connection establishment according to this embodiment. The operation of establishing a connection to the IAB node 105 on a new communication path will be described.

[0067] In S900, the IAB donor 101 establishes a path connection by assigning an IP address to each of the subordinate IAB nodes 102 to 106, thereby forming an initial network topology. After the UE 119 establishes a Uu access connection to the IAB node 105 in S901 and S902, if the UE 119 requests a URLLC slice in S903, the IAB donor 101 assigns the slice to the UE 119 in S904.

[0068] In S905, a wireless link failure causes a disconnection between IAB node 104 and IAB node 105, and in S906, IAB node 105 switches to a new path for communication via IAB node 103. In S907, IAB nodes 103 to 105 notify the IAB donor 101 of the switching of the communication path using an RRC message.

[0069] The IAB donor 101, which has received the notification from each IAB node in S908, determines whether the dynamic information has been updated in the dynamic information update detection unit S306. In this embodiment, each IAB node notifies the path switching using an RRC message. As an example, the communication path switching may be notified by another message including a congestion notification in flow control feedback by BAP or a notification of the number of UEs (a handover notification by RRC or a notification of the number of UEs accessing the own station using a BAP notification).

[0070] In S909, the IAB donor 101 detects updates to the dynamic information by referring to the RRC and BAP message notifications received from each IAB node and determines which slice the dynamic information corresponds to. In the first embodiment, since the number of hops for the IAB node 105 was updated from 3 to 4 in S401, the slice type is determined to be URLLC in S405, and the number of hops for the dynamic information is referred to in S408, and path updates for the IAB node 105 are determined in S411.

[0071] In S910, the IAB donor 101 requests a connection candidate list from the IAB node 105 that has decided to update the path, by an RRC message. In S911, the IAB node 105 transmits the connection candidate list generated based on the RRM measurement results to the IAB donor 101 by an RRC message.

[0072] In S912, the IAB donor 101 obtains the connection destination candidate list (S503) of the IAB node 105 according to the flowchart shown in Fig. 5. Next, information indicating the number of hops is selected from the NSSAI list managed by the slice management unit 307 and the dynamic information managed by the dynamic information management unit 309 (S505), and the IAB node 103 with the smallest number of hops is selected as the connection destination node (S509). In S913, the IAB donor 101 notifies the IAB node 105 of a change in the communication path with the IAB node 103 by using an RRC control message.

[0073] In S914, the IAB node 105 establishes a new path with the IAB donor 101 via the IAB node 103. The IAB donor 101 instructs a new F1-C connection with the IAB node 105. Here, the description is given assuming that each control message is exchanged via BAP and RRC, but this is not limited to this and the communication path may be instructed, for example, by exchanging application layer messages. In S915, the IAB node 105 notifies the IAB donor 101 that the path update has been completed.

[0074] This allows an IAB node 105, in which a communication failure has occurred and a communication path needs to be switched, to switch to a communication path that satisfies the slice requirements requested by the UE connected to that node.

[0075] Fig. 10 is a diagram showing the topology after a new path is connected in embodiment 1. In the wireless communication system 100, after the sequence of Fig. 9 is executed, the IAB node 105 establishes a connection with the IAB node 103 via the path 1000, thereby becoming able to supply URLLC slices to the UE 119.

[0076] As described above, for a specific slice that has become unsatisfied with the requirements at the IAB nodes 102 to 105 due to path switching caused by a wireless link failure, by forming a communication path with a new connection destination, it is possible to support the slice that does not meet the requirements.

[0077] <Embodiment 2> In the first embodiment, a case has been described in which a link failure occurs between the IAB node 105 to which a URLLC is requested from a UE and its parent node, the IAB node 104, in the wireless communication system 100, and the number of hops fluctuates due to switching of the communication path. In the second embodiment, a method for determining a new connection destination that can support the sliced ​​eMBB requested by the UE 118 in the case in which congestion due to buffer overflow occurs in the IAB node 104, which is the parent node of the IAB node 105, will be described.

[0078] The same configurations, functions, and processes as those in the first embodiment are designated by the same reference numerals, and detailed descriptions thereof will be omitted.

[0079] 11 is a flowchart for determining a new communication path when an eMBB slice is requested according to this embodiment. The configurations, functions, and processes shown in FIGS. 2 to 9, excluding FIG. 4, described in the first embodiment, are the same. In addition, in the second embodiment, it is assumed that no radio link failure has occurred between IAB node 104 and IAB node 105. It is also assumed that the dynamic information of each IAB node is that shown in 802 in FIG. 8.

[0080] In S1100, after the IAB donor 101 receives a flow control feedback notification from the IAB node 104 in a congested state, it collects a connection candidate list of the IAB node 105 located downstream of the IAB node 104 on the communication path.

[0081] In S1101, the congested IAB node 104 is set as the provisional destination IAB node. S1102 to S1107 are repeated (S1108) for the number n of IAB nodes to connect to. In S1103, it is determined whether the slice requested by the UE is eMBB. If the requested slice is eMBB (Yes in S1103), the process proceeds to S1104, where information indicating the available buffer capacity (buffer information) is selected from the dynamic information in S801.

[0082] In S1105, if the free buffer capacity of the connection candidate IAB node is larger than the free buffer capacity of the provisional destination IAB node, the process proceeds to S1106, and the connection candidate IAB node with the larger free buffer capacity is determined as the provisional destination IAB node. If the free buffer capacity of the connection candidate IAB node is equal to or smaller than the free buffer capacity of the provisional destination IAB node, the process proceeds to S1107, and the free buffer capacity of the other connection candidate IAB nodes is determined.

[0083] After repeating this process for all connection candidate IAB nodes n in S1108, the provisional connection destination IAB node is determined as the connection destination IAB node in S1109. Then, an RRC message is sent to instruct IAB node 105 to connect to the IAB node with the largest free buffer capacity among the connection candidate IAB nodes. In this embodiment, IAB node 106 with the largest free buffer capacity in the dynamic information shown in S801 of FIG. 8 is selected as the IAB node with the largest free buffer capacity.

[0084] When an IAB node 105 receives notification from an IAB donor 101 of a destination IAB node 106 with the maximum free buffer capacity, it can connect to the new destination IAB node 106 and be provided with a communication path with the maximum free buffer capacity.

[0085] It should be noted that IAB node 105 may establish a new communication path with IAB node 106 while maintaining the communication path with IAB node 104, thereby forming a multipath connection.

[0086] 12 shows the topology after the new communication path is connected according to this embodiment. In the wireless communication system 100, by establishing a connection between the IAB donor 101 and the IAB node 104 and a multipath 1200 according to the flowchart shown in FIG. 9, it becomes possible to provide a communication path supporting eMBB slices to the UE 119.

[0087] In this embodiment, the description has been given assuming that the IAB node with the largest free buffer capacity is connected. However, it may be possible to connect to any IAB node whose free buffer capacity is equal to or greater than a predetermined threshold (second threshold). In this case, if there are multiple IAB nodes whose free buffer capacity is equal to or greater than the predetermined threshold, the IAB node 105 may determine which of the multiple IAB nodes to connect to based on other dynamic information such as the proportion of UL transmission.

[0088] <Embodiment 3> In the third embodiment, a process of determining a new connection destination that can support the sliced ​​MIoT requested by the UE 118 when the number of UEs connected to the IAB node 105 exceeds a predetermined threshold will be described.

[0089] Figure 13 shows a flowchart for determining a new communication path when an MIoT slice is requested according to this embodiment. Here, it is assumed that Figures 2 to 9, other than Figure 4 described in embodiment 1, can be shown in the same diagram, and that no radio link failure has occurred between IAB node 104 and IAB node 105. The dynamic information of each IAB node is assumed to be that shown in 803 in Figure 8. Note that in this embodiment, it is assumed that each communication path supporting MIoT can provide communication to a total of 256 UEs.

[0090] In S1300, after receiving an RRC signal or a BAP notification from the IAB node 105 notifying that the number of UEs connected to the IAB donor 101 has exceeded a threshold, the IAB donor 101 collects a connection candidate list for the IAB node 105. In S1301, the IAB node 104 that is the parent node of the IAB node 105 with the number of UEs connected thereto is set as the provisional connection destination IAB node.

[0091] The processes from S1302 to S1307 are repeatedly executed for n connection candidate nodes (S1309). In S1303, it is determined whether the slice requested by the connection candidate IAB node is MIot, and if it is MIot, the process proceeds to S1304, where information indicating the total number of UEs (user number information) is selected from the dynamic information of S801.

[0092] In S1305, if the total number of UEs in the connection candidate IAB nodes is smaller than the total number of UEs in the provisional destination IAB node, the process proceeds to S1306, where the connection candidate IAB node with the smaller total number of UEs is determined as the provisional destination IAB node. If the total number of UEs in the connection candidate IAB nodes is equal to or greater than the total number of UEs in the provisional destination IAB node, the process proceeds to S1307, where another connection candidate IAB node is determined.

[0093] After repeating the process for all connection candidate IAB nodes n in S1309, the provisionally connected IAB node is determined as the destination IAB node in S1308, and an RRC control message is sent to IAB node 105 to notify it of the selection of the IAB node with the smallest total number of UEs. IAB node 106 has the smallest total number of UEs in S801.

[0094] The IAB node 105 that receives notification of the destination IAB node 106 with the minimum total number of UEs from the IAB donor 101 connects to the new destination IAB node 106 and receives the path with the minimum total number of UEs.

[0095] 14 shows a topology after a new communication path is connected in the third embodiment. If 106 UEs are already connected to the IAB node 104 and the IAB node located upstream thereof on the communication path, the IAB node 105 located downstream of the IAB node 104 on the communication path can only connect an additional 150 UEs. In this case, in the wireless communication system 100, a connection between the IAB donor 101 and the multipath 1400 can be established for the IAB node 104 according to the flowchart of FIG. 9. As a result, the UE 1552 connected to the IAB node 105 can be assigned to a communication path supporting an MIoT slice via the IAB node 106, thereby providing the UE 1552 with communication supporting an MIoT.

[0096] In one example, the IAB donor 101 may switch the communication path based on the number of UEs that can be connected to a specific IAB node. For example, in the example of FIG. 14, 100 UEs are connected upstream of the IAB node 104, and two UEs are connected upstream of the IAB node 106. In such a case, for the IAB node 105 to which the number of connected UEs exceeds a threshold, the IAB donor 101 may determine the connection destination based on the total number of UEs connected to the IAB node and its upstream IAB node among the connection candidate IAB nodes. In this way, when the number of connectable UEs over the entire communication path is determined, by switching the connection destination of the downstream IAB node, it is possible to provide communication that supports the MIoT slice type to the newly connecting UE.

[0097] In this embodiment, the description has been given assuming that the IAB node is connected to the IAB node with the smallest total number of connected UEs or the largest number of connectable UEs. However, it may be connectable to any IAB node with a total number of UEs equal to or less than a predetermined threshold (third threshold) or a number of connectable UEs equal to or greater than the predetermined threshold. In this case, if there are multiple IAB nodes with a total number of UEs equal to or less than the predetermined threshold, IAB node 105 may determine which of the multiple IAB nodes to connect to based on other dynamic information.

[0098] <Other embodiments> The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0099] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention.

[0100] Path switching has been described in the first to third embodiments. However, when RLF (Radio Link Failure) is notified as a BAP control message rather than a degradation in communication quality, a multipath connection may be established by continuing the original communication path with a newly determined connection destination.

[0101] In addition, in the first to third embodiments, a single slice is rescued at the IAB nodes 102 to 106, but if multiple slices that do not satisfy the requirements occur within a predetermined period, the slice with the largest number of requested UEs may be rescued with priority. Furthermore, if the slice with the largest number of requested UEs cannot be rescued, a new communication path may be selected to rescue the slice with the next largest number of requested UEs.

[0102] In this embodiment, the URLLC sets the prerequisite destination node based on the number of hops to the IAB donor, and if the number of hops is the same, the delay time is compared. In one example, the IAB donor may associate the type of dynamic information to be selected with its priority for each slice type and store them in the storage unit 202. In this case, in the process of S505, a predetermined type of dynamic information may be selected based on the slice type, and comparison may be performed in order of priority.

[0103] In the present embodiment, the connection control unit 304 to the dynamic information management unit 309 in FIG. 3 are described as being provided in the IAB donor 101. However, as an example, they may be provided in a network node on the core network side, or in the wireless communication network 100. [Explanation of symbols]

[0104] 100 wireless communication system, 101 IAB donor, 102 to 106 IAB nodes, 110 to 120 UE, 201 control unit, 202 storage unit, 203 wireless communication unit, 204 antenna control unit, 301 signal transmission unit, 302 signal reception unit, 303 data storage unit, 304 connection control unit, 305 dynamic information update detection unit, 306 connection candidate list collection unit, 307 slice management unit, 308 communication path selection unit, 309 dynamic information management unit

Claims

1. A control device for an IAB (Integrated Access and Backhaul) network, comprising: an IAB node for relaying a connection between an IAB donor of the IAB network and a predetermined IAB node, and acquiring means for acquiring multiple types of dynamic information indicating communication statuses of IAB nodes connectable to the predetermined IAB node; a selection means for selecting at least one type of dynamic information from the plurality of types of dynamic information acquired by the acquisition means based on a slice type that the predetermined IAB node should support; a path control means for controlling a communication path between the predetermined IAB node and the IAB donor in accordance with the at least one type of dynamic information selected by the selection means; a first receiving means for receiving a Radio Resource Control (RRC) signal including a request for re-establishment of a communication path, a notification of a radio link failure, and flow control feedback from the predetermined IAB node; Equipped with When the first receiving means receives the RRC signals from multiple IAB nodes within a predetermined period, the path control means controls the communication path of the IAB node with a large number of connected user devices by giving priority to the communication path.

2. the plurality of types of dynamic information includes hop count information indicating a hop count from the IAB donor to the connectable IAB node; If the slice type is URLLC (Ultra-Reliable and Low Latency Communications), the selecting means selects the hop count information as the at least one type of dynamic information; 2. The control device according to claim 1, wherein the path control means switches the communication path so as to connect to an IAB node having the smallest number of hops from the IAB donor among the connectable IAB nodes.

3. the plurality of types of dynamic information includes hop count information indicating a hop count from the IAB donor to the connectable IAB node; If the slice type is URLLC (Ultra-Reliable and Low Latency Communications), the selecting means selects the hop count information as the at least one type of dynamic information; 2. The control device according to claim 1, wherein the path control means sets the communication path so that the specified IAB node connects to the connectable IAB node whose hop count indicated by the hop count information is equal to or less than a first threshold.

4. the plurality of types of dynamic information includes buffer information indicating free buffer capacity of the connectable IAB node; If the slice type is eMBB (enhanced Mobile BroadBand), the selecting means selects the buffer information as the at least one type of dynamic information; 4. The control device according to claim 1, wherein the path control means switches the communication path so that the specified IAB node is connected to an IAB node with the largest free buffer capacity among the connectable IAB nodes.

5. the plurality of types of dynamic information includes buffer information indicating free buffer capacity of the connectable IAB node; If the slice type is eMBB (enhanced Mobile BroadBand), the selecting means selects the buffer information as the at least one type of dynamic information; 4. The control device according to claim 1, wherein the path control means sets a communication path so that the specified IAB node connects to the connectable IAB node whose free buffer capacity indicated by the buffer information is equal to or greater than a second threshold.

6. the plurality of types of dynamic information includes user number information indicating the number of user devices connecting to the connectable IAB node; If the slice type is MIoT (Massive Internet of Things), the selecting means selects the number of users information as the at least one type of dynamic information; 6. The control device according to claim 1, wherein the path control means switches the communication path so as to connect to an IAB node having the smallest number of UEs connected thereto, among the connectable IAB nodes.

7. the plurality of types of dynamic information includes user number information indicating the number of user devices connecting to the connectable IAB node; If the slice type is MIoT (Massive Internet of Things), the selecting means selects the number of users information as the at least one type of dynamic information; The control device according to any one of claims 1 to 5, characterized in that the path control means sets a communication path so that the specified IAB node connects to the connectable IAB node where the number of user devices indicated by the user number information is equal to or less than a third threshold.

8. The control device according to any one of claims 1 to 7, wherein the connectable IAB node is an IAB node that supports the slice type.

9. The method further includes a second receiving means for receiving a slice request signal from a user device connected to the predetermined IAB node, the slice request signal requesting a communication path that supports a slice type, 9. The control device according to claim 1, wherein when the second receiving means receives the slice request signal, the path control means indicates the IAB node to which the specified IAB node is connected.

10. A control device as described in Claim 9, characterized in that when the slice request signal is received by the second receiving means and the path control means determines that there is no communication path that supports the slice type requested in the slice request signal, it further has a notification means for notifying the user device that sent the slice request signal that the slice type cannot be supported.

11. A control device described in any one of claims 1 to 10, characterized in that when the first receiving means receives the RRC signal, the acquiring means acquires the dynamic information, and the path control means controls the communication path between the IAB donor and the specified IAB node so as to support the slice type that the specified IAB node can support.

12. the selection means selects a plurality of types of dynamic information from the plurality of types of dynamic information based on the slice type to be supported by the predetermined IAB node; 12. The control device according to claim 1, wherein the path control means controls the communication paths based on the plurality of types of dynamic information selected by the selection means.

13. The method further includes a storage unit that stores information in which the slice type and a priority in determining a communication path are associated with each of the plurality of types of dynamic information, 13. The control device according to claim 12, wherein the path control means selects dynamic information from the plurality of types of dynamic information selected by the selection means in descending order of priority and controls the communication path.

14. A control method executed by a control device of an IAB (Integrated Access and Backhaul) network, comprising: An IAB node for relaying a connection between an IAB donor of the IAB network and a predetermined IAB node, and acquiring multiple types of dynamic information indicating communication statuses of IAB nodes connectable to the predetermined IAB node; Selecting at least one type of dynamic information from the acquired multiple types of dynamic information based on a slice type that the predetermined IAB node should support; controlling a communication path between the given IAB node and the IAB donor in response to the selected at least one type of dynamic information; receiving a Radio Resource Control (RRC) signal from the predetermined IAB node, the RRC signal including a request for re-establishment of a communication path, a notification of a radio link failure, and flow control feedback; Including, A control method characterized by controlling, when the RRC signals are received from a plurality of IAB nodes within a predetermined period, a communication path of an IAB node to which a large number of user equipments are connected, with priority.

15. The computer of the control device of the IAB (Integrated Access and Backhaul) network an IAB node for relaying a connection between an IAB donor of the IAB network and a predetermined IAB node, and acquiring multiple types of dynamic information indicating communication statuses of IAB nodes connectable to the predetermined IAB node; a selection step of selecting at least one type of dynamic information from the plurality of types of dynamic information acquired in the acquisition step based on a slice type that the predetermined IAB node should support; a path control step of controlling a communication path between the predetermined IAB node and the IAB donor in accordance with the at least one type of dynamic information selected in the acquisition step; receiving a Radio Resource Control (RRC) signal from the predetermined IAB node, the RRC signal including a request for re-establishment of a communication path, a notification of a radio link failure, and flow control feedback; Execute In the receiving step, when the RRC signals are received from multiple IAB nodes within a predetermined period, in the path control step, a program characterized by controlling the communication path of an IAB node with a large number of connected user devices by priority.

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