JP7135175B2 - Terminal device, network device, control method, and program - Google Patents

Description

The present invention relates to paging technology in wireless communications.

In the 3rd Generation Partnership Project, a new radio access technology of the 5th generation (hereinafter referred to as “5G”) is under consideration (see Non-Patent Document 1). In the 5G system, it is assumed that a base station device, also called NR gNB, includes a plurality of devices called Central Unit (CU) and Distributed Unit (DU). A DU is also called a Transmission Receiver Point (TRP). Here, DU processes layers including at least the physical (PHY) layer at least below the radio resource control (RRC) layer, and CU processes layers including the RRC layer above the layer controlled by the DU. is expected to be performed. Also, it is assumed that a plurality of DUs are connected to one CU. Further, one DU forms one or more beams by beamforming, for example, and establishes a connection with a terminal device using at least one of the beams. That is, the base station apparatus includes at least one CU and a plurality of DUs connected to the CU, and each DU forms one or more beams to form a large number of beams. , is connected to a terminal device on at least one of the plurality of beams.

3GPP Contribution, RP-160671, March 2016 3GPP, TS36.331

In a conventional LTE (Long Term Evolution) system, when a terminal device is called, a paging message is simultaneously transmitted from the core network to all base station devices to which the same Tracking Area Code (TAC) is assigned. Then, the base station apparatus that has received the paging message transmits the paging message by radio signal in the cell provided by itself, and calls the terminal apparatus staying in one of the cells. If such a paging scheme is applied to the 5G system as it is, the paging message will be transmitted by a large number of beams, so radio resources such as spatial resources will be wasted, and the paging message will interfere with other signals. can be put away

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a technique for calling a terminal device with high radio resource utilization efficiency and low interference.

In order to achieve the above object, a terminal device according to an aspect of the present invention is connectable to one or more base station devices forming one or more beams, respectively, and has a connected state including an RRC_Connected state and an RRC_Idle state. and an intermediate state between the RRC_Connected state and the RRC-Idle state, the terminal device being operable in a non-connected state, wherein the intermediate state is not connected to any of the one or more base station devices, monitoring means for monitoring a connection target beam to be used when the terminal device establishes a connection with any one of the one or more base station devices ; and reporting means for reporting information on the connection target beam to the base station apparatus forming the connection target beam.

Further, to achieve the above object, a network device according to an aspect of the present invention is a network device in a network including one or more base station devices each forming one or more beams, wherein the one or more from a terminal device capable of operating in a connected state consisting of an RRC_Connected state and a non-connected state consisting of an RRC_Idle state and an intermediate state between the RRC_Connected state and the RRC_Idle state. relating to a connection target beam to be used when the terminal device establishes a connection with any one of the one or more base station devices in the intermediate state in which the terminal device is not connected to any of the one or more base station devices Receiving means for receiving a report from the terminal device that has moved out of the range of the tracking area; and a portion of a plurality of beams formed by the one or more base station devices that includes the connection target beam and a control means for controlling to perform paging to the terminal device using the beam of .

According to the present invention, it is possible to call a terminal device with high radio resource utilization efficiency and low interference.

The figure which shows the structural example of a radio|wireless communications system. FIG. 2 is a diagram showing an example hardware configuration of a terminal device and a network device; The figure which shows the functional structural example of a terminal device. FIG. 2 is a diagram showing a functional configuration example of a network device; FIG. 4 is a diagram showing a first example of the flow of call processing executed in a wireless communication system; FIG. 5 is a diagram showing a second example of the flow of call processing executed in the wireless communication system; FIG. 10 is a diagram showing a third example of the flow of call processing executed in the wireless communication system;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Configuration of wireless communication system)
FIG. 1 shows a configuration example of a wireless communication system according to this embodiment. A radio communication system according to this embodiment is, for example, a fifth generation (5G) mobile radio communication system, and includes a base station apparatus (NR gNB) and a terminal apparatus. A wireless connection is established between the base station apparatus and the terminal apparatus, and wireless signals are transmitted or received. A base station apparatus is connected to a core network, for example, by wire (connected by a line including a wireless section in some cases), and is connected to another base station apparatus (not shown) via the core network. Note that the core network is connected to an external network such as the Internet via a gateway, for example, and the base station apparatus can be connected to the external network via the core network. Note that the core network includes various core network nodes.

The base station apparatus of this embodiment has a first part (first control device) that executes control of a lower layer in communication and a part (second control device) that executes control of a higher layer. Consists of In FIG. 1, the first control device is indicated by DU (Distributed Unit)/TRP (Transmission Receiver Point), and the second control device is indicated by CU (Central Unit). In the following description, the first control device will be called DU, and the second control device will be called CU. Here, the DU of the present embodiment is configured to perform at least physical (PHY) layer control, while not performing at least radio resource control (RRC) layer and above control. On the other hand, the CU is configured to perform control of layers above the DU, including the RRC layer. A CU may be connected to one DU, but may be connected to multiple DUs as shown in FIG. A line connecting the CU and the DU is called a fronthaul line. The CU and DU may be directly connected as in FIG. 1, or a switch (not shown) connected to a plurality of DUs is connected to the CU, and communication between the CU and each DU is based on control by the switch. may be done. Note that if a switch is used, communication between DUs can be performed without going through the CU. Note that DUs, CUs (base station devices), and devices in the core network are hereinafter collectively referred to as network devices.

A DU can form multiple beams by beamforming. As shown in FIG. 1, a large number of DUs form a plurality of beams, thereby increasing the number of beams that can be formed by the base station apparatus. As a result, many users can be accommodated and the total throughput can be increased. can. On the other hand, as the number of users accommodated increases, so does the number of paging messages sent. At this time, for example, if all DUs of a plurality of base station apparatuses assigned the same Tracking Area Code (TAC) simultaneously transmit the same paging message, radio resources are occupied by the transmission of the paging message. Also, in such a case, the probability that the paging message interferes with the communication between the base station apparatus with the same TAC and the base station apparatus with the different TAC increases.

On the other hand, in this embodiment, the terminal device monitors the beam to be used when establishing connection with any base station device in a non-connected state in which it is not connected to any base station device. A beam to be used when establishing a connection with a base station apparatus is hereinafter referred to as a connection target beam. A terminal device reports information about its connection target beam to the base station device that forms that connection target beam, at least based on, for example, the transition of the connection target beam in accordance with the movement of the terminal device. Then, based on the information, the network equipment (DU/CU or node in the core network) performs control to limit beams for transmitting paging messages.

Note that the terminal device can report information on the connection target beam while in the non-connected state. Note that in LTE, an RRC_Connected state and an RRC_Idle state are defined. For example, between these states, a state in which an RRC connection is not established but a predetermined signal can be transmitted can be defined. At this time, the non-connection state here includes such a state in which an RRC connection is not established but a predetermined signal can be transmitted.

Also, the terminal device can report information about the beam to be connected, further based on the number of times the beam to be connected has transitioned in the non-connected state. For example, the terminal device may report the state of the beam to be connected at that time every time the beam to be connected transits a predetermined number of times, such as three times. Note that the terminal device can report the connection target beam each time the connection target beam transitions a predetermined number of times while the non-connection state continues. That is, for example, when the non-connection state continues, the terminal device can report when the connection target beam has transitioned a predetermined number of times since the previous report. Note that once the terminal device is in a connected state, the network device can track the beam used by the terminal device for connection. Therefore, the terminal device can reset this count to 0 when transitioning to the connected state.

In addition, the terminal device can report information on connection target beams further based on the number of connection target beams that have transitioned in the non-connection state. For example, when the connection target beam is alternately switched between two beams, the terminal device counts the number of transitioned connection target beams as "2" regardless of the number of times. Then, when the number reaches a predetermined number such as "3", the terminal device reports the beam to be connected. Note that the terminal device can report the connection target beam each time the number of connection target beams transitioned while the non-connection state continues reaches a predetermined number. That is, the terminal device can report, for example, when the non-connection state continues, or when the terminal device has transitioned to a predetermined number of connection target beams since the previous report. Note that the terminal device can reset this number to 0 when transitioning to the connected state. Note that the terminal device may use a combination of the number of transitions of the connection target beam and the number of connection target beams of transition destinations. For example, the terminal device may report the connection target beam when the number of transitions of the connection target beam reaches a predetermined number, or when the number of connection target beams of transition destinations reaches a predetermined number.

Further, when the connection target beam transitions in the non-connection state, the terminal device determines that the connection target beam is different from the DU that provides the connection target beam before the transition and the DU that provides the connection target beam after the transition. Beams may be reported. If the DU from which the connection target beam is provided does not change, the terminal device reports the connection target beam based on the number of transitions of the connection target beam and the number of connection target beams at the transition destination, for example, as described above. can do

Note that the condition for the terminal apparatus to report the beam to be connected can be specified by the base station apparatus. Upon receiving this condition from the base station apparatus, the terminal apparatus can report the beam to be connected according to the condition. Note that "receiving from the base station apparatus" here also includes receiving from a node of the core network via the base station apparatus.

On the other hand, the network device (base station device (DU/CU) or core network node) receives the above-mentioned report of the beam to be connected from the terminal device. Then, the network device controls to perform paging to the terminal device using some beams including the reported connection target beam among the plurality of beams formed by one or more base station devices. conduct. For example, when the terminal device reports the above every time the beam to be connected transits, the network device can perform control so that paging is performed only in the reported beam to be connected. Further, when the terminal device reports the above every time the connection target beam transitions three times, the network device determines the connection target beam, the first beam adjacent to the connection target beam, and the first beam adjacent to the first beam. 2 beams may be controlled to perform paging. Further, even when the terminal device reports the above every time the number of transitioned connection target beams reaches three, the network device performs paging in the connection target beam, the first beam, and the second beam. can be controlled to do so. Furthermore, when the terminal device reports the above every time the DUs providing the connection target beams before and after the transition are different, the network device performs paging in each beam provided by the DUs providing the connection target beams after the transition. can be controlled to do so.

For example, if the network device that performs the above control is a node of the core network, the paging message will be sent only to the DU that forms the beam for paging. Therefore, no paging message is sent to a second CU different from the first CU to which the DU is connected and to other DUs under the first CU. Therefore, it is possible to reduce the load on the backhaul line, the fronthaul line, and the CU and DU that do not perform paging.

Also, for example, when the network device that performs the above control is a CU, the core network node sends a paging message to a base station device (CU) having the same TAC, for example. Then, a CU can transmit a paging message to its subordinate DU when the received paging message is to be transmitted by a beam formed by a DU subordinate to the CU. Therefore, it is possible to prevent the fronthaul line from being unnecessarily wasted. Also, since paging messages are not sent to DUs that do not page, the load on many DUs can be reduced. Furthermore, the core network node does not need to manage information about the beam to which the paging message should be transmitted and manage the destination of the paging message, thereby reducing the processing load.

Further, for example, when the network device that performs the above control is a DU, the node of the core network sends a paging message to a base station device (CU) having the same TAC, for example, and the CU sends a message to all DUs under its control. paging messages can be forwarded to A DU then sends out its paging message as a radio signal when the paging message is to be sent by a beam formed by it. According to this, the nodes and CUs of the core network do not need to manage information about beams to which paging messages are to be transmitted, and manage destinations of paging messages, thereby reducing the processing load.

As described above, the terminal device in the unconnected state notifies the network side of the information indicating which beam should be used when establishing a connection as the information of the beam to be connected. , paging is performed using only some of the beams. This makes it possible to prevent waste of radio resources and suppress interference with communications on other beams.

The configuration of the terminal device and network device that perform such processing and the flow of processing will be described below.

(Hardware configuration)
FIG. 2 shows a hardware configuration example of the terminal device and the network device. In one example, the terminal device and network device have a hardware configuration as shown in FIG. In the terminal device and the network device, the CPU 201 executes a program that is recorded in, for example, one of the ROM 202, the RAM 203, and the external storage device 204 and that realizes each function of the terminal device and the network device as described above.

The terminal device and the network device then control the communication circuit 205 by, for example, the CPU 201 to communicate with other devices. Note that the communication circuit 205 of the network device can communicate with other network devices, for example, through a wired line. Also, when the network device is a DU, the communication circuit 205 can form one or more (plurality) beams to perform wireless communication with the terminal device. In addition, the communication circuit 205 of the terminal device is configured to be connectable to at least one of the beams formed by the communication circuit 205 of the DU, and is configured to be able to wirelessly communicate with the DU using these beams. be. In the configuration of FIG. 2, the terminal device and the network device are shown schematically as having one communication circuit 205, but are not limited to this, and may have a plurality of communication circuits. For example, a DU has a first communication circuit for fronthaul communication and a second communication circuit for wireless communication. Also, the CU may have a first communication circuit for communication over the fronthaul line and a second communication circuit for communication with the core network. Also, the terminal device may have, for example, a first communication circuit conforming to the fourth generation or earlier wireless communication standards and a second communication circuit conforming to the fifth generation wireless communication standards. Also, the terminal device may have a wireless communication circuit for standards other than cellular, such as wireless LAN, and may also have a wired communication circuit used for wired connection such as USB connection.

Note that the terminal device and the network device may be provided with dedicated hardware for executing each function, or a part may be executed by hardware and the other part may be executed by a computer that operates a program. Also, all functions may be performed by computers and programs.

(Functional configuration)
First, an example of the functional configuration of the terminal device will be described with reference to FIG. In one example, the terminal device includes a wireless communication section 301 , a connection target beam monitoring section 302 and a report control section 303 . In addition, the terminal device is a general communication terminal or an electronic device having a communication function other than these, and can have various functional units. not shown.

Radio communication section 301 is configured to be connectable to at least one of a plurality of beams formed by one or more DUs in one or more base station apparatuses by controlling an antenna (not shown). The radio communication unit 301, for example, generates a baseband signal from data to be transmitted or information generated by the report control unit 303, converts the baseband signal into a radio frequency signal, and transmits the radio signal from an antenna. can be output. Also, the wireless communication unit 301 can convert a wireless signal received via an antenna into a baseband signal and extract information from the baseband signal.

In a non-connected state in which connection is not established with any base station apparatus, the connection target beam monitoring unit 302 determines which beam among the beams formed by any one of the base station apparatuses establishes connection. It monitors whether it becomes a connection target beam that should be used for connection. Note that, for example, the connection here is the RRC connection, and the disconnected state is a state different from the RRC_Connected state. For example, the connection target beam monitoring unit 302 observes the radio quality using a predetermined signal (for example, a reference signal) transmitted from each beam, and selects the beam with the best radio quality or a beam having a predetermined level or higher as the connection target beam. Determined as Note that the connection target beam monitoring unit 302 does not necessarily have to determine one beam as the connection target beam, and may specify a plurality of connection target beams. You can decide not to.

The report control unit 303 executes control for reporting information about the connection target beam obtained as a result of monitoring by the connection target beam monitoring unit 302 to the base station apparatus (network apparatus). For example, the report control unit 303 can control the wireless communication unit 301 to notify the base station apparatus of information on the connection target beam on condition that the connection target beam transition occurs in the non-connection state. Further, the report control unit 303, for example, on the condition that the number of transitions of the connection target beam in the non-connection state reaches a predetermined number of times, wirelessly communicates to notify the base station apparatus of information on the connection target beam. 301 can be controlled. Further, for example, the report control unit 303 wirelessly notifies the base station apparatus of information on the connection target beam on condition that the number of transition destination beams of the connection target beam in the non-connection state has reached a predetermined number. It can control the communication unit 301 . In addition, for example, the report control unit 303, on the condition that the DU that provides the beam before the transition of the connection target beam in the non-connection state and the DU that provides the beam after the transition of the connection target beam, are different. It can control the wireless communication unit 301 to notify the station device. In addition, the report control unit 303 may report information on the connection target beam when a predetermined period of time has elapsed since the information on the connection target beam was previously reported in the non-connected state. Note that the above conditions are only examples, and the report control unit 303 may control the wireless communication unit 301 to report information on the connection target beam based on a combination of these conditions or other conditions. good. Note that the report control unit 303 may receive a condition for reporting information on the beam to be connected from the network device via the wireless communication unit 301 .

Note that the information report on the beam to be connected can be transmitted when, for example, an RRC connection is established, but may be transmitted in a state in which the RRC connection is not established (in a non-connected state). For example, as an intermediate state between the RRC_Connected state and the RRC_idle state, a state in which an RRC connection is not established but a predetermined signal can be transmitted is defined, and in the intermediate state, information on the beam to be connected is reported. good too.

Note that, for example, when the TAC of the base station apparatus to which the DU of the connection target beam belongs before the transition and the TAC of the base station apparatus to which the DU after the transition belongs are different, the report control section 303 establishes an RRC connection to establish the connection target beam. Information about the beam may be sent to the post-transition DU.

Next, a functional configuration example of the network device will be described with reference to FIG. A network device is, as described above, for example a node of a core network, a CU or a DU in a base station device, and is not limited to any of these. For this reason, the following description focuses on the functions for executing the functions according to the present embodiment, and omits the description of the functions unique to each of these devices. The network device includes, for example, a communication unit 401 , a connection target beam information acquisition unit 402 , a call control unit 403 and a condition notification unit 404 .

For example, when the network device is a DU, the communication unit 401 can form one or more beams by controlling an antenna (not shown), and uses at least one of the beams to communicate with the terminal device. configured to be connectable. Note that when the network device is a DU, the communication unit 401 can communicate with the CU, a switch arranged between the CU and the DU, or other DU via the switch via a fronthaul line. configured as Also, when the network device is a CU, the communication unit 401 can communicate with a node in the core network or a CU in another base station device via a backhaul line, and can communicate with a DU under its control via a fronthaul line. can communicate. Also, when the network device is a node of the core network, the communication unit 401 can communicate with the CU in the base station device via the backhaul line.

The connection target beam information acquisition unit 402 acquires information about the connection target beam reported by the terminal device. For example, when the network device is a DU, the connection target beam information acquisition unit 402 directly acquires information on the connection target beam from the terminal device by radio signal. When the network device is a CU, the connection target beam information acquisition unit 402 acquires information on the connection target beam received and transferred by the DU from the terminal device. If the network device is a node of the core network, the connection target beam information acquisition unit 402 acquires information on the connection target beam that the DU received from the terminal device and transferred to the CU, and further transferred by the CU.

The call control unit 403 specifies some beams based on the acquired information about the beams to be connected, and executes control for calling (paging) the terminal device using the specified beams. This prevents the paging message from being transmitted in an unnecessary number of beams, improves the efficiency of using radio resources, and prevents the paging message from interfering with other signals.

For such control, the call control unit 403 stores and manages the information specifying the terminal device in association with the beam to be connected reported from the terminal device. For example, when the network device is a node of the core network, the paging control unit 403 sets the information of the terminal device whose connection target beam is a beam that can be formed by all the base station devices under its own control. manage with Further, for example, when the network device is a CU, the call control unit 403 manages the information of the terminal device which designates the beam that can be formed by the DU under its control as the connection target beam, together with the connection target beam. Further, for example, when the network device is a DU, the call control unit 403 manages the information of the terminal device which designates one of the beams formed by itself as the connection target beam, together with the connection target beam.

Then, for example, when the network device is a node of the core network, the call control unit 403 specifies a connection target beam corresponding to the terminal device when executing a call to the terminal device, and selects the specified beam. Identify the DU to form. Then, the paging control unit 403 transmits a paging message designating the identified beam to the CU that has the DU under its control. Upon receiving the paging message, the CU transfers the paging message to the DU forming the designated beam, and causes the DU to transmit the paging message as a radio signal. In this case, since no paging message is transmitted to the CU of the base station apparatus that does not transmit the paging message, it is possible to reduce the processing load on the CU and reduce the traffic on the backhaul line.

On the other hand, if the network device is a CU, the core network node transmits a paging message containing information indicating which terminal device the paging message is addressed to, to all subordinate CUs. Then, when the paging message is received from the node of the core network, the call control unit 403 in the CU determines whether or not the terminal device to which the paging message is addressed is managed by itself. Then, when the call control unit 403 manages the destination terminal device by itself, the paging message is transferred to the DU forming the connection target beam corresponding to the terminal device, and the paging message is transferred to the DU. Causes a paging message to be sent as a radio signal. In this case, the node of the core network does not perform processing according to the connection target beam, so paging can be performed with a small processing load. Also, since paging messages are not sent to DUs that do not send paging messages, the processing load on each DU can be reduced, and the amount of communication on the fronthaul line can be reduced.

Also, when the network device is a DU, the core network node transmits a paging message including information indicating which terminal device the paging message is addressed to, to all CUs under its control. Also, the CU forwards the paging message to all DUs under its control. Then, upon receiving the paging message, the call control unit 403 in the DU determines whether or not it itself manages the terminal device of the destination of the paging message. Then, when the call control unit 403 manages the destination terminal device by itself, the call control unit 403 transmits a paging message as a radio signal using the connection target beam corresponding to the terminal device. In this case, the nodes and CUs of the core network do not perform processing according to the connection target beam, so paging can be performed with a small processing load.

Note that the paging control unit 403 can transmit the paging message not only in the connection target beam, but also in a beam separated by a predetermined range from that beam. For example, when a plurality of groups including one or more beams are configured in advance, the paging control unit 403 controls so that the paging message is transmitted in all or part of the beams included in the group. you can go In addition, the call control unit 403 determines the range of the beam to which the paging message is to be transmitted according to the reporting conditions of the beam to be connected (the number of transitions of the beam to be connected/the number of transition destinations/transition of the connection destination DU, etc.). good too. For example, when the call control unit 403 makes a report every time the connection target beam transits twice or each time the number of transition destinations of the connection target beam reaches three, the paging control unit 403 performs paging in the connection target beam and its adjacent beams. can send messages. In addition, when the DUs before and after the transition corresponding to the beam to be connected are different, the paging control unit 403 can transmit the paging message in the beam that can be formed by the DU after the transition.

The condition notification unit 404 notifies the terminal device of the conditions for reporting information on the beam to be connected. Note that if the reporting conditions are determined in advance, the condition notification unit 404 may be omitted.

It should be noted that some functions may be distributed among, for example, multiple network devices. For example, the call control unit 403 is distributed to a core network node or CU and DU, the core network node or CU manages information of DU forming a connection target beam for each terminal device, DU is the terminal device can manage information on beams to be connected corresponding to . A core network node or CU may then send a paging message to the DU corresponding to the terminal, and the DU may send the paging message over one or more beams including the beam corresponding to the terminal.

(Processing flow)
Next, the flow of processing executed by the terminal device and the network device as described above will be described. First, an example in which the network device is a DU will be described with reference to FIG. In this example, in order to simplify the explanation, DU1 forming beam group A and CU1 subordinate to DU1, DU2 forming beam group B and CU2 subordinate to DU2, and core network nodes (represented by "CN" in FIG. 5) only. However, there may be multiple CUs, each subordinate to multiple DUs. Also, for example, different core network nodes may be arranged for different TACs.

First, it is assumed that the terminal device stays within the range of beam group A (S501), and the beam to be connected to the terminal device is one beam group A beam. At this time, for example, DU1 may notify the reporting conditions of the beam to be connected (S502). After that, it is assumed that the terminal device satisfies the conditions for reporting the connection target beam, for example, the number of transitions of the connection target beam reaches a predetermined number while staying within the range of the beam group A in the non-connection state (S503). ). Then, the terminal device notifies DU1 of information about the beam to be connected at that time (S504). DU1 associates and stores and manages the reported connection target beam and the information specifying the terminal device (S505).

Thereafter, it is assumed that the terminal device moves to the range of the beam group B while remaining in the non-connected state, and satisfies the reporting conditions of the beam to be connected (S506). For example, if the reporting condition is that the DUs that provide the connection target beams before and after the transition are different, the terminal device satisfies the connection target beam reporting conditions when it moves into the range of the beam group B. In this case, the terminal device reports information on the beam to be connected to DU2 (S507). Then, DU2 associates and stores and manages the reported connection target beam and the information specifying the terminal device (S508).

At this time, a notification for updating information that associates the beam to be connected with the terminal device may be transmitted and received between DU2 and DU1. For example, DU2 may communicate updated information to DU1 (eg, via CU2 and CU1). Note that DU1 may determine that the terminal device no longer exists within the range of beam group A, for example, in response to not receiving a report of a connection target beam for a predetermined period of time. As a result, DU1 can know that there is no terminal device within the range of beam group A formed by itself, and can avoid unnecessary paging message transmission.

After that, it is assumed that paging for the terminal device occurs. In this case, the core network node first transmits a paging message to CU1 and CU2, which are CUs of the base station apparatus belonging to the TAC managed by itself (S509). CU1 and CU2 then forward the paging message to DU1 and DU2, respectively (S510). DU2 transmits the paging message as a radio signal because the terminal device exists within the range of the beam group B formed by itself (S511). On the other hand, DU1 does not transmit a paging message because there is no terminal within the beam group A range.

Next, an example in which the network device is a CU will be described with reference to FIG. First, it is assumed that the terminal device stays within the range of beam group A (S601) and the beam to be connected to the terminal device is one of beam group A. At this time, the reporting conditions of the beam to be connected may be notified, for example, from CU1 via DU1 (S602). After that, it is assumed that the terminal device satisfies the reporting condition of the beam to be connected while staying within the range of the beam group A in the non-connected state (S603). Then, the terminal device notifies DU1 of information about the beam to be connected at that time, and DU1 transfers the information to CU1 (S604). CU1 associates and stores and manages the reported connection target beam and the information specifying the terminal device (S605).

Thereafter, it is assumed that the terminal device moves to the range of the beam group B while remaining in the non-connected state, and satisfies the reporting conditions of the beam to be connected (S606). In this case, the terminal device reports information about the beam to be connected to DU2, and DU2 transfers the information to CU2 (S607). Then, CU2 associates and stores and manages the reported connection target beam and the information specifying the terminal device (S608).

At this time, a notification for updating information that associates the beam to be connected with the terminal device may be transmitted and received between CU2 and CU1. For example, CU2 may communicate updated information to CU1 (eg, via the core network). Note that the CU1 may determine that the terminal device no longer exists within the range of the beam group A, for example, in response to not receiving a connection target beam report for a predetermined period of time. As a result, CU1 is able to know that the terminal device no longer exists within the range of beam group A formed by DU1 under its control, so that unnecessary paging messages are not transmitted. can be done.

After that, it is assumed that paging for the terminal device occurs. In this case, the node of the core network first transmits a paging message to CU1 and CU2, which are CUs of the base station apparatus belonging to the TAC managed by itself (S609). Then, CU2 transfers the paging message to DU2 because the terminal device exists within the range of beam group B formed by DU2 under its control (S610). On the other hand, CU1 does not transfer the paging message to DU1 because there is no terminal device within the range of beam group A formed by DU1 under its control. After that, DU2 sends out the transferred paging message as a radio signal (S611). On the other hand, since DU1 does not receive the paging message, it does not send out the paging message.

In addition, although the example of FIG. 6 shows the case where only the CU associates and manages the terminal device and its corresponding beam to be connected, control may be distributed between the CU and the DU. For example, the CU may associate and store the terminal device and information on the DU that provides the connection target beam, and the DU may associate and store the terminal device and the connection target beam. For example, CU1 associates and manages the terminal device and DU1 in S605, and DU1 associates and manages the terminal device and the connection target beam. In addition, CU2 associates and manages the terminal device and DU2 in S608, and DU2 associates and manages the terminal device and the connection target beam. Thereby, for example, when receiving a paging message, CU1 and CU2 can appropriately control whether or not to transfer the paging message to the DU under their control. In addition, since CU1 and CU2 do not need to manage the beam to be connected, the amount of information to be managed is reduced. The amount of information to be processed can be reduced. Also, beams for sending paging messages in DUs can be appropriately limited, and sending unnecessary paging messages is suppressed.

Next, an example in which the network device is a node of the core network will be described with reference to FIG. First, it is assumed that the terminal device is staying within the range of beam group A (S701) and the beam to be connected to the terminal device is one of beam group A. At this time, for example, the reporting conditions of the beam to be connected may be notified from the node of the core network via CU1 and DU1 (S702). After that, it is assumed that the terminal device satisfies the reporting condition of the beam to be connected while staying within the range of the beam group A in the non-connected state (S703). Then, the terminal device notifies DU1 of information about the beam to be connected at that time, DU1 transfers the information to CU1, and CU1 transfers the information to the node of the core network (S704). The core network node associates and stores and manages the reported connection target beam and the information specifying the terminal device (S705).

Thereafter, it is assumed that the terminal device moves to the range of the beam group B while remaining in the non-connected state, and satisfies the reporting conditions of the beam to be connected (S706). In this case, the terminal device reports information about the beam to be connected to DU2, DU2 transfers the information to CU2, and CU2 transfers the information to the node of the core network (S707). Then, the core network node stores and manages the reported connection target beam and the information specifying the terminal device in association with each other (S708).

After that, it is assumed that paging for the terminal device occurs. In this case, since the terminal device exists within the range of beam group B formed by DU2, the node of the core network transmits a paging message to CU2, which has DU2 under its control (S709). On the other hand, the node of the core network does not transmit the paging message to CU1 because the terminal device does not exist within the range of the beam group formed by the DUs under the control of CU1. Then, CU2 transfers the received paging message to DU2 under its own control (S710). After that, DU2 transmits the transferred paging message as a radio signal (S711). On the other hand, CU1 and DU1 do not receive the paging message, so no paging message is sent from DU1.

In the example of FIG. 7, only the core network node manages the terminal device and its corresponding connection target beam in association with each other. may be For example, the core network node associates and stores information on the terminal device and the DU that provides the connection target beam or the CU that has the DU under its control, and the CU or DU associates the terminal device with the connection target beam. can be stored. For example, the core network node associates and manages the terminal device and DU1 (or CU1) in S705, and DU1 (or CU1) associates and manages the terminal device and the connection target beam. Also, the core network node associates and manages the terminal device and DU2 (or CU2) in S708, and DU2 (or CU2) associates and manages the terminal device and the connection target beam. This allows, for example, the core network node to appropriately limit the CUs to which the paging message is sent. In addition, since the nodes of the core network do not need to manage the beams to be connected, the amount of information to be managed is reduced. The amount of information to be processed can be reduced. Also, in the DU (or CU), beams for sending paging messages can be appropriately limited, and unnecessary paging message sending is suppressed.

As described above, in this embodiment, the terminal device monitors the connection target beam to be used when connecting to the base station device in the non-connection state, and notifies the network device of the information on the connection target beam. . Based on the notification, the network device then pages the terminal device using a portion of the available beams. This prevents the paging message from being sent out in a large number of beams unnecessarily, improves the utilization efficiency of radio resources, and suppresses interference with other signals.

Claims (7)

Connectable to one or more base station devices forming one or more beams respectively , a connected state consisting of an RRC_Connected state, and a non-connected state consisting of an RRC_Idle state and an intermediate state between the RRC_Connected state and the RRC_Idle state A terminal device operable in
A connection target beam to be used when the terminal device establishes a connection with any of the one or more base station devices in the intermediate state in which the terminal device is not connected to any of the one or more base station devices. a monitoring means for monitoring;
reporting means for reporting information on the connection target beam to the base station apparatus forming the connection target beam based on movement out of the range of the tracking area;
A terminal device comprising: The reporting means performs the reporting using a message transmitted for a beam to be used when establishing a connection at the destination,
The terminal device according to claim 1, characterized by: each of the one or more base station devices includes one or more devices each capable of performing physical layer control and forming one or more beams;
The reporting means reports information about the connection target beam when a device forming the connection target beam before transition and a device forming the connection target beam after transition are different.
3. The terminal device according to claim 1 or 2, characterized by: further comprising receiving means for receiving from at least one of the one or more base station devices a condition for the reporting means to report information on the connection target beam;
The terminal device according to any one of claims 1 to 3, characterized in that: A network device in a network including one or more base station devices each forming one or more beams,
From a terminal device that is connectable to the one or more base station devices and can operate in a connected state consisting of an RRC_Connected state, and a non-connected state consisting of an RRC_Idle state and an intermediate state between the RRC_Connected state and the RRC_Idle state, Should be used when the terminal device establishes a connection with any of the one or more base station devices in the intermediate state in which the terminal device is not connected to any of the one or more base station devices receiving means for receiving a report on the connection target beam from the terminal device that has moved out of the range of the tracking area;
Control means for controlling paging to the terminal device using a part of the beams including the connection target beam among the plurality of beams formed by the one or more base station devices;
A network device comprising: Connectable to one or more base station devices forming one or more beams, respectively, a connected state consisting of an RRC_Connected state, and a non-connected state consisting of an RRC_Idle state and an intermediate state between the RRC_Connected state and the RRC_Idle state A control method performed by a terminal device operable in
A connection target beam to be used when the terminal device establishes a connection with any of the one or more base station devices in the intermediate state in which the terminal device is not connected to any of the one or more base station devices. to monitor;
Reporting information about the connection target beam to the base station device forming the connection target beam based on the movement out of the range of the tracking area;
A control method comprising: Connectable to one or more base station devices forming one or more beams, respectively, a connected state consisting of an RRC_Connected state, and a non-connected state consisting of an RRC_Idle state and an intermediate state between the RRC_Connected state and the RRC_Idle state A computer provided in a terminal device capable of operating in
A connection target beam to be used when the terminal device establishes a connection with any of the one or more base station devices in the intermediate state in which the terminal device is not connected to any of the one or more base station devices. to monitor,
causing the base station apparatus that forms the connection target beam to report information on the connection target beam based on the movement out of the range of the tracking area;
program for.

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