Communication device, control method, and program

Abstract

To perform more effective communication load balance.SOLUTION: A communication device acting as a first relay node for relaying communication between a base station and a user device in a mobile communication system includes: receiving means for receiving a notification signal indicating the presence of a second relay node different from the first relay node; and instruction means for instructing one or more user devices connecting to the first relay node to perform handover to the second relay node when the notification signal is received.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to communication load balancing processing in a mobile communication system. [Background technology]

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

[0003] In backhaul communications using IAB technology, relay devices called IAB nodes relay communications from base stations called IAB donors via millimeter wave communications. By using IAB, it is possible to expand area coverage at a lower cost than conventional wired communications such as optical fiber.

[0004] When IAB is used, user equipment periodically notifies a base station of surrounding environment information during backhaul communication. The base station, upon receiving the surrounding environment information from the user equipment, requests the user equipment to hand over to another IAB node as necessary. Patent Document 2 discloses a technology in which a user equipment notifies a base station of surrounding environment information and the base station takes the initiative in performing a handover of the user equipment. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2019-534625 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-217562 Summary of the Invention [Problem to be solved by the invention]

[0006] In situations where a large number of UEs are densely packed (such as in stadiums or large-scale offline events), the communication load of the IAB nodes to which these UEs connect may be high. Hereinafter, IAB nodes installed in the vicinity and normally used are referred to as "normal IAB nodes." In such cases, to reduce the load on the normal IAB nodes, IAB nodes that can be installed in vehicles and used as temporary relay stations (hereinafter referred to as "temporary IAB nodes") may be installed. In such situations, conventional handover procedures cannot be used to hand over user equipment between IAB nodes. Therefore, it is desirable for the base station to take the initiative in performing handover of user equipment between IAB nodes.

[0007] However, when using the technology disclosed in Patent Document 2, a large number of UEs must report surrounding environment information to a base station (IAB donor) via a heavily loaded normal IAB node. Furthermore, a user equipment handover procedure is required for each user equipment. Therefore, in an environment where many user equipment are congested, the amount of communication between the user equipment and the base station increases significantly.

[0008] The present invention has been made in view of the above problems, and aims to provide a technique that enables more effective communication load balancing. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems, a communication device according to the present invention has the following configuration: That is, the communication device operates as a first relay node that relays communication between a base station and a user equipment in a mobile communication system, a receiving means for receiving a notification signal indicating the presence of a second relay node different from the first relay node; an instruction means for instructing one or more user equipments connected to the first relay node to perform handover to the second relay node when the notification signal is received by the receiving means; Equipped with. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a technique that enables more effective communication load balancing. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a block diagram showing a hardware configuration of the communication device. [Figure 2] FIG. 2 is a block diagram showing the functional configuration of the communication device. [Figure 3A] FIG. 10 is a diagram illustrating a system configuration before load balancing. [Figure 3B] FIG. 10 is a diagram illustrating a system configuration after load balancing. [Figure 4] FIG. 10 is a sequence diagram within the system in load balancing processing. [Figure 5] 10 is a flowchart showing the operation of a temporary IAB node. [Figure 6A] 10 is a flowchart illustrating the operation of a normal IAB node. [Figure 6B] 10 is another flowchart illustrating the operation of a normal IAB node. [Figure 7] 10 is a flowchart showing the operation of the UE. [Figure 8] 1 is a flowchart showing the operation of an IAB donor. [Figure 9] 10 is another flowchart illustrating the operation of a normal IAB node. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0013] (First embodiment) As a first embodiment of a communication device according to the present invention, a communication device operating as an IAB node, which is a relay node in a mobile communication system, will be described below. The mobile communication system may be, for example, a 5G mobile communication system, and the IAB node may be a Radio Access Network (RAN) node that supports both a New Radio (NR) access link and an NR backhaul link.

[0014] <Device configuration> FIG. 1 is a block diagram showing an example of the hardware configuration of a communication device. The communication device 101 includes a control unit 102, a storage unit 103, a wireless communication unit 104, and an antenna control unit 105. The control unit 102 controls the entire device by executing a control program stored in the storage unit 103. The storage unit 103 stores the control program executed by the control unit 102 and various information used for control (cell information, connected terminal information, IAB routing information, etc.). Various operations described below are realized by the control unit 102 executing the control program stored in the storage unit 103. The wireless communication unit 104 performs cellular network communication such as LTE and 5G that conform to the 3GPP standard. The antenna control unit 105 controls an antenna for wireless communication performed by the wireless communication unit 104.

[0015] 2 is a block diagram showing an example of the software functional configuration of a communication device. Communication device function 201 includes signal transmission unit 202, signal reception unit 203, data storage unit 204, connection control unit 205, broadcast information detection unit 206, handover request unit 207, and broadcast information generation unit 208. Signal transmission unit 202 and signal reception unit 203 perform cellular network communication such as LTE or 5G compliant with the 3GPP standard with other devices (IAB node, UE). Data storage unit 204 stores and holds software programs, IAB routing information, information on connected terminals, and the like.

[0016] The connection control unit 205 controls the wireless communication performed by the wireless communication unit 104. The detection unit 206 detects broadcast information from nearby IAB nodes. The handover request unit 207 transmits a radio resource control (RRC) message to the UE to request a handover. The broadcast information generation unit 208 broadcasts a signal indicating the presence of the own device (communication device 101, which is an IAB node).

[0017] <System configuration and outline of operation> 3A and 3B are diagrams showing a system configuration, and in particular show exemplary states before and after a UE handover occurs in association with a load balancing process, which will be described later.

[0018] IAB donor 311 has IAB nodes 301 to 306 under it, and is configured to establish a communication path between the donor and multiple nodes as indicated by path 320. Here, it is assumed that IAB nodes 301 to 306 are "normal IAB nodes."

[0019] In a large-scale event venue 330, many UEs 400 are densely packed together, forming a UE group 331. The many UEs 400 included in the UE group 331 are basically connected to the nearest normal IAB node (the one with the best radio wave conditions), IAB node 306. As a result, IAB node 306 is under an extremely high load. In such a case, as shown in FIG. 3B , a temporary IAB node (e.g., an in-vehicle IAB node 307) may be temporarily installed to increase communication capacity and distribute the load at the event venue 330.

[0020] In such a situation, there is a demand for rapid load balancing from the heavily loaded normal IAB node (IAB node 306) to the temporary IAB node (IAB node 307). However, in the current 3GPP standard, each UE collects surrounding environment information and notifies the IAB donor 311 of the surrounding environment information, which is then analyzed by the IAB donor 311. If the IAB donor 311 determines that the UE should be handed over to another IAB node, it notifies the UE of an RRC connection reestablishment request (RRC Reconfiguration message). The format of the RRC Reconfiguration message is specified in 3GPP TR 38.331 6.2.2. After this process, the UE is handed over to another IAB node.

[0021] As such, even if a temporary IAB node is deployed under the current 3GPP standard, it is necessary to wait for a decision from the IAB donor, and it is not possible to quickly hand over the UE. Furthermore, the above sequence must be performed for each UE. Therefore, in situations where many UEs are congested, a large number of messages are exchanged just to perform a handover, further increasing the load on the regular IAB node.

[0022] Therefore, in this embodiment, a form will be described in which a quick handover of the UE is realized without the intervention of the IAB donor's decision.

[0023] <Overall system operation> 4 is a diagram showing the processing sequence within the system for load balancing processing. UE 400 establishes a communication path with IAB donor 311 via IAB node 306, which is a normal IAB node. In order to balance the load of IAB node 306, IAB node 307, which is a temporary IAB node, is newly installed within event venue 330.

[0024] In S601, the IAB node 307 transmits notification information by using a beacon, a dedicated message, etc. to announce its presence. At this time, the notification information may include information such as "that it is a temporarily installed IAB node" or "that it is an IAB node temporarily installed in association with the IAB node 306."

[0025] The broadcast information is broadcast in accordance with the 3GPP standard (3GPP TS 38.413, Section 9.3.1), particularly the broadcast information format defined in the Radio Network Layer as the broadcast information format. This format is capable of broadcasting up to 256 types of information, and the above-mentioned broadcast information is added to the reserved or empty areas in the current standard for broadcasting.

[0026] In S602, upon receiving the notification information from the temporary IAB node 307, the IAB node 306 performs a process of determining one or more UEs to be subjected to handover.

[0027] In S603, the IAB node 306 issues a handover instruction to one or more UEs that are the targets of the determination process in S602. This instruction is notified using an RRC Reconfiguration message defined in the 3GPP standard. Specifically, a dedicatedSIB1-Delivery message is used to specify the ID of the IAB node 307 that will be the handover destination (reconnection destination). Alternatively, a new definition dedicated to this notification may be added to the RRC Reconfiguration message field.

[0028] In S604, upon receiving the handover request, the UE 400 initiates handover from the IAB node 306 to the IAB node 307. Specifically, the UE 400 performs a synchronization establishment process and a RACH process for the IAB node 307, and connects to the IAB node 307. The synchronization establishment process and the RACH process here are processes that are defined in the 3GPP standard and are performed when the UE connects to the IAB node for the first time. That is, these processes are processes that establish link synchronization between the UE and the IAB node by performing a synchronization between the UE and the IAB node, a RACH (Random Access Channel) frequency determination process, and the like.

[0029] In S605, when the UE 400 completes the connection with the IAB node 307, the UE 400 notifies the temporary IAB node 307 of the completion of handover. This notification uses an RRC Reconfiguration Complete message defined in the 3GPP standard. In addition, information that "handover has been performed between IAB nodes (i.e., from the IAB node 306 to the IAB node 307)" is added to this notification so that the IAB donor 311 can perform an appropriate route information update process.

[0030] In S606, upon receiving the handover completion notification, the IAB node 307 relays this notification and transmits it to the upper IAB donor 311. In S607, the IAB donor 311 updates the communication path information of the UE corresponding to the handover completion notification.

[0031] <Operation of each device> FIG. 5 is a flowchart showing the operation of IAB node 307, which is a temporary IAB node.

[0032] In F501, the IAB node 307 transmits broadcast information indicating its own presence. This broadcast information may include "that it is a temporarily installed IAB node" or "that it is an IAB node temporarily installed in association with the IAB node 306." In F502, the IAB node 307 waits for a connection from a UE. In F503, when the IAB node 307 detects a connection from a UE, it performs synchronization / RACH processing with the UE and establishes a link.

[0033] In F504, the IAB node 307 receives an RRC Reconfiguration Complete message that is a notification of the completion of handover of the UE. In F505, the IAB node 307 relays the RRC Reconfiguration Complete received in F504 and transmits it to the upper IAB donor 311.

[0034] FIG. 6A is a flowchart illustrating the operation of IAB node 306, which is a normal IAB node.

[0035] In F601, the IAB node 306 detects broadcast information transmitted from the IAB node 307. In F603, the IAB node 306 performs processing to determine one or more UEs to be targets for handover. In this processing, processing is performed to appropriately distribute the load between the IAB node 306 and the IAB node 307. For example, approximately half of the multiple UEs connected to the IAB node 306 are determined to be targets for handover. Alternatively, one or more UEs are determined to be targets for handover so that the communication volume between the IAB node 306 and the IAB node 307 is approximately the same. In F604, the IAB node 306 performs handover notification to one or more UEs determined to be targets for handover. An RRC Reconfiguration message is used for this notification.

[0036] 6B is another flowchart showing the operation of IAB node 306, which is a normal IAB node. This differs from FIG. 6A in that processing in F602 is added before processing in F603 to determine one or more UEs to be subjected to handover.

[0037] In F602, the IAB node 306 determines whether the broadcast information detected in F601 includes information indicating that the IAB node is a temporarily installed IAB node. If it does (i.e., the broadcast signal is transmitted from a temporary IAB node), the process proceeds to F603. On the other hand, if it does not (i.e., the broadcast signal is transmitted from a normal IAB node), the process ends.

[0038] Alternatively, it may be determined whether the broadcast information detected in F601 includes information indicating that the node is a temporarily installed IAB node associated with the IAB node 306. If it does (i.e., the broadcast signal was transmitted from a temporary IAB node associated with the IAB node 306), the process proceeds to F603. On the other hand, if it does not (i.e., the broadcast signal was transmitted from a temporary IAB node associated with a node other than the IAB node 306, or a normal IAB node), the process ends. By performing such processing, it is possible to prevent normal IAB nodes other than the IAB node 306 from performing the process shown in FIG. 4 when they receive a broadcast signal from the IAB node 307, which is a temporary IAB node. In other words, the IAB nodes 301 to 305 do not perform the process shown in FIG. 4 even when they receive a broadcast signal from the IAB node 307.

[0039] 7 is a flowchart showing the operation of the UE 400. This process is executed by one or more UEs among the many UEs 400 included in the UE group 331 that have received the RRC Reconfiguration message.

[0040] In F701, when the UE 400 receives an RRC Reconfiguration message serving as a handover notification from the currently connected IAB node 306, the UE 400 starts handover processing. That is, the UE 400 starts handover from the IAB node 306 to the IAB node 307. In F702, the UE 400 performs synchronization establishment processing and RACH processing with the IAB node 307, and connects to the IAB node 307. In F703, the UE 400 transmits an RRC Reconfiguration Complete message serving as a handover completion notification to the IAB node 307.

[0041] 8 is a flowchart showing the operation of IAB donor 311. As described above, IAB donor 311 is not directly involved in the load balancing process, but updates communication path information for one or more UEs that have performed handover as a result of the load balancing process.

[0042] In F801, the IAB donor 311 receives an RRC Reconfiguration Complete from the IAB node 307, which is a handover completion notification. In F802, the IAB donor 311 determines whether the handover completion notification includes information indicating that "handover has been performed between IAB nodes." If it does, the process proceeds to F803; if it does not, the process ends. In F803, the IAB donor 311 updates communication path information corresponding to one or more UEs that have performed handover.

[0043] As described above, according to the first embodiment, the IAB node, which is a relay node in the mobile communication system, takes the initiative in executing UE handover. Specifically, when the IAB node 306, which is a normal IAB node, detects the IAB node 307, which is a temporary IAB node, it controls one or more UEs among the many UEs currently connected to the IAB node 306 to hand over to the IAB node 307. This control enables quick UE handover without the need for the IAB donor's decision, and enables appropriate communication load balancing between the normal IAB node and the temporary IAB node.

[0044] (Variation) The IAB node 306, which is a normal IAB node, may be configured to further use other information in the process (S602, F603) for determining one or more UEs to which handover is to be performed.

[0045] FIG. 9 is a flowchart showing the operation of a normal IAB node according to a modified example. In FIG. 9, a process (F903) for checking whether the conditions for handing over a UE are met is added to FIG. 6B. In F903, for example, it is checked whether the processing load of the IAB node 306 itself exceeds a given threshold, or whether the number of UEs currently connected to the IAB node 306 exceeds a given threshold. If the given threshold is exceeded, it is determined that the conditions for handing over are met. Furthermore, it may also be possible to check weighting based on the communication volume (bandwidth) used by one or more UEs to be subjected to handover.

[0046] After the processing sequence shown in FIG. 4 is completed, the communication load is balanced between the normal IAB node and the temporary IAB node. However, it is possible that the load may become uneven over time. Therefore, the normal IAB node and the temporary IAB node may be configured to periodically exchange the number of connected UEs / communication volume. If an imbalance exceeding a given threshold is detected, the processing shown in S602 to S607 in FIG. 4 may be executed again.

[0047] Furthermore, although the temporary IAB node 307 is expected to be installed within the event venue 330, in some cases, not all UEs in the UE group 331 are necessarily within the coverage area of ​​the IAB node 307. Therefore, the IAB node 306 may be configured to check a Measurement Report notification periodically transmitted by the UE prior to the process (S602, F603) for determining one or more UEs to be subjected to handover. More specifically, the IAB node 306 may check, based on this notification, whether the UE that transmitted this notification has discovered the IAB node 307. Then, only UEs that have discovered the IAB node 307 may be selected as candidates for one or more UEs in the process (S602, F603).

[0048] Furthermore, when installing IAB node 307, which is a temporary IAB node (i.e., prior to S601 in FIG. 4), the IAB node 307 may be configured to control the upper node to which it connects. In other words, if IAB node 307 becomes a lower node of IAB node 306, the load will not be balanced for communication between IAB node 306 and its upper node (IAB node 304). Therefore, when IAB node 306 attempts to connect as a lower node, IAB node 306 may reject the connection of IAB node 307 or guide IAB node 307 to a connection destination.

[0049] (Other Examples) 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.The present invention can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0050] 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. [Explanation of symbols]

[0051] 101 communication device; 102 control unit; 103 storage unit; 104 wireless communication unit; 105 antenna control unit; 201 communication device function; 202 signal transmission unit; 203 signal reception unit; 204 data storage unit; 205 connection control unit; 206 notification information detection unit; 207 handover request unit; 208 notification information generation unit

Claims

1. A communication device that operates as a first relay node that relays communication between a base station and a user equipment in a mobile communication system, comprising: a receiving means for receiving a notification signal indicating the presence of a second relay node different from the first relay node; an instruction means for instructing one or more user equipments connected to the first relay node to perform handover to the second relay node when the notification signal is received by the receiving means; A communication device comprising:

2. The first relay node is an integrated access and backhaul (IAB) node that supports both a backhaul link with a base station and an access link with a user equipment.

2. The communication device according to claim 1.

3. The instructing means instructs the handover using a radio resource control (RRC) message.

3. The communication device according to claim 1 or 2.

4. The notification signal includes first information indicating that the second relay node is a temporarily installed relay node.

4. The communication device according to claim 1, wherein the communication device is a communication device.

5. The notification signal further includes second information indicating that the second relay node is a relay node established in association with the first relay node.

5. The communication device according to claim 4.

6. The instruction means instructs one or more user equipments connected to the first relay node to perform handover to the second relay node only when the broadcast signal includes the first information.

6. The communication device according to claim 4 or 5.

7. The instruction means instructs one or more user equipments connected to the first relay node to perform handover to the second relay node only when the broadcast signal includes the second information.

6. The communication device according to claim 5.

8. further comprising a determination means for determining whether or not a processing load in the first relay node exceeds a given threshold; The instruction means instructs one or more user equipments connected to the first relay node to perform handover to the second relay node only when the determination means determines that the processing load at the first relay node exceeds the given threshold.

8. A communication device according to claim 1, wherein the communication device comprises: a first communication unit;

9. The processing load is the number of user equipments connected to the first relay node and / or the amount of communication processed by the first relay node.

9. The communication device according to claim 8.

10. A method for controlling a communication device that operates as a first relay node that relays communication between a base station and user equipment in a mobile communication system, comprising: a receiving step of receiving a notification signal indicating the presence of a second relay node different from the first relay node; an instruction step of instructing one or more user equipments connected to the first relay node to perform handover to the second relay node when the notification signal is received by the receiving step; A control method comprising:

11. A program for causing a computer to execute the control method according to claim 10.

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