WO2022239244A1 - Wireless base station, terminal, and wireless communication method - Google Patents

Abstract

According to the present invention, a wireless base station receives a handover suspension message from a source wireless base station and transmits a release request message for a target wireless base station within a cell group to the target wireless base station. The wireless base station transmits a release request message that includes a reason for the release request.

Description

Radio base station, terminal and radio communication method

The present disclosure relates to radio base stations, terminals, and radio communication methods that support conditional handover.

The 3rd Generation Partnership Project (3GPP) has specified the 5th generation mobile communication system (also called 5G, New Radio (NR) or Next Generation (NG)), and the next generation specification called Beyond 5G, 5G Evolution or 6G We are also proceeding with

For example, 3GPP Release 16 stipulates conditional handover (CHO: Conditional Handover), and when a specific execution condition is met, a terminal (User Equipment, UE)-initiated handover is performed. can run.

In CHO, a handover candidate cell and handover execution conditions (which may be called a transition) to the candidate cell are set in advance for the terminal.

This allows the terminal to handover to the target radio base station (which may also be called the target cell) without waiting for a handover instruction from the network.

In addition, 3GPP is also considering CHO (CHO with SCG configuration) for candidate cells (secondary cells (SCells)) that configure secondary cell groups (SCGs) (Non-Patent Document 1).

However, with the current CHO, there is a problem that it is difficult for UEs and radio base stations (gNBs) to operate properly when handover to a candidate cell that configures an SCG fails.

Therefore, the following disclosure is made in view of this situation, and provides a radio base station, a terminal, and a radio communication method that can realize appropriate operations when handover by CHO with SCG configuration fails. With the goal.

One aspect of the present disclosure is a receiving unit (RRC/Xn processing unit 120) that receives a handover abort message from a source radio base station, and a target radio base station release request to a target radio base station in a cell group. a transmission unit (RRC/Xn processing unit 120) that transmits a message, the transmission unit being the radio base station (gNB100) that transmits the release request message containing the reason for the release request.

One aspect of the present disclosure is a transmission unit (RRC/Xn processing unit 120) that transmits a message requiring release of the own station to the target radio base station in the cell group, and a control that controls a timer for conditional handover. section (control section 140), and the transmission section is a radio base station (gNB100) that transmits the release-required message according to the expiration of the timer or the state of radio resources in the own station.

One aspect of the present disclosure is a control unit (control unit 240) that controls execution of conditional handover, and if the conditional handover fails and another candidate cell is selected, only to control unit 240 A terminal (UE 200) including a transmitting section (RRC processing section 220) that transmits a response to a setting request.

One aspect of the present disclosure is a control unit (control unit 240) that controls execution of conditional handover, and if the conditional handover fails, among the candidate cells, either the primary cell or the secondary cell or A terminal (UE 200) including a transmitting section (RRC processing section 220) that transmits a report including information indicating that both have failed.

An aspect of the present disclosure includes receiving a handover abort message from a source radio base station and sending a release request message of the target radio base station to a target radio base station in a cell group, In the transmitting step, the wireless communication method transmits the release request message including a handover cancellation reason.

FIG. 1 is an overall schematic configuration diagram of a radio communication system 10. As shown in FIG. FIG. 2 is a functional block configuration diagram of the gNB100. FIG. 3 is a functional block configuration diagram of UE200. FIG. 4 is a diagram illustrating a sequence example (part 1) of CHO with SCG configuration according to operation example 1. FIG. FIG. 5 is a diagram illustrating a sequence example (part 2) of CHO with SCG configuration according to operation example 1. FIG. FIG. 6 is a diagram illustrating a sequence example (part 1) of CHO with SCG configuration according to operation example 2. In FIG. FIG. 7 is a diagram illustrating a sequence example (part 2) of CHO with SCG configuration according to operation example 2. In FIG. FIG. 8 is a diagram illustrating a sequence example of CHO with SCG configuration according to operation example 3. In FIG. FIG. 9 is a diagram showing an example of the hardware configuration of gNB100 and UE200.

Hereinafter, embodiments will be described based on the drawings. The same or similar reference numerals are given to the same functions and configurations, and the description thereof will be omitted as appropriate.

(1) Overall Schematic Configuration of Radio Communication System FIG. 1 is an overall schematic configuration diagram of a radio communication system 10 according to the present embodiment. The radio communication system 10 is a radio communication system according to 5G New Radio (NR), and includes a Next Generation-Radio Access Network 20 (hereinafter NG-RAN 20 and terminals 200 (User Equipment 200, hereinafter UE 200).

The wireless communication system 10 may be a wireless communication system complying with a scheme called Beyond 5G, 5G Evolution or 6G, or may be a wireless communication system complying with Long Term Evolution (LTE).

NG-RAN 20 includes a radio base station 100 (hereinafter gNB 100). Note that the specific configuration of the radio communication system 10 including the number of gNBs and UEs is not limited to the example shown in FIG. Also, in the case of a radio communication system conforming to LTE, an eNB may be used instead of a gNB.

NG-RAN 20 actually includes multiple NG-RAN Nodes, specifically gNBs (or ng-eNBs), and is connected to a 5G-compliant core network (5GC, not shown). Note that NG-RAN 20 and 5GC may simply be referred to as a "network".

The gNB100 is an NR-compliant radio base station and performs NR-compliant radio communication with the UE200. gNB100 and UE200 control radio signals transmitted from multiple antenna elements to generate beams with higher directivity Massive MIMO, carrier aggregation (CA) that uses multiple component carriers (CC) in a bundle, And dual connectivity (DC) in which communication is performed simultaneously between the UE and multiple NG-RAN Nodes, etc., can be supported.

In this embodiment, Multi-Radio Dual Connectivity (MR-DC) may be implemented in which one gNB 100 constitutes the master node (MN) and the other gNB 100 constitutes the secondary node (SN).

In other words, the UE200 supports dual connectivity that connects to multiple gNB100s (which may be read as cells, the same applies hereinafter).

Any gNB 100 may be included in the master cell group (MCG), and the other gNB 100 may be included in the secondary cell group (SCG). The gNB 100 may also be called a wireless communication node, node or network equipment.

The type of DC may be Multi-RAT Dual Connectivity (MR-DC), which uses multiple radio access technologies, or NR-NR Dual Connectivity (NR-DC), which uses only NR. MR-DC may also be E-UTRA-NR Dual Connectivity (EN-DC), where eNB constitutes the master node (MN) and gNB constitutes the secondary node (SN), or vice versa NR -E-UTRA Dual Connectivity (NE-DC) is acceptable.

A master cell group (MCG) and a secondary cell group (SCG) may be set in the DC. The MCG may include a primary cell (PCell), and the SCG may include a secondary cell (SCell).

In addition, the SCell may include a primary/secondary cell (PSCell). A PSCell is a type of SCell, but may be interpreted as a special SCell having functions equivalent to those of a PCell. In PSCell, like PCell, transmission of PUCCH (Physical Uplink Control Channel), contention type random access procedure (CBRA), Radio Link Monitoring (downlink radio quality monitoring) function, etc. may be executed. .

UE200 can transition between cells formed by gNB100. "Transition" typically means handover between cells, but may include behavior of UE 200, such as cell reselection, such as changing the connected cell.

In particular, in this embodiment, the radio communication system 10 may support conditional handover (CHO). CHO may be interpreted as a handover procedure that is executed only if an execution condition is met.

A CHO may be defined as a handover performed by the UE 200 when one or more handover execution conditions are met. The UE 200 may start evaluating execution conditions upon receiving a CHO configuration, and stop evaluating execution conditions upon execution of a handover (legacy handover or conditional handover).

The CHO configuration includes the CHO candidate cell configuration generated by the candidate cell (candidate gNB) and the execution conditions generated by the handover source source cell (gNB).

The execution condition may consist of one or two trigger conditions (CHO event A3/A5 defined in 3GPP TS38.331). A single reference signal (RS) type is triggered and up to two different trigger quantities (e.g. Reference Signal Received Power (RSRP) and Reference Signal Received Quality (RSRQ ), RSRP and Signal-to-Interference plus Noise power Ratio (SINR), etc.) may be set at the same time.

Note that if the UE 200 receives an HO instruction (which may be called an HO command) (no CHO setting) before the CHO execution condition is satisfied, the HO procedure (3GPP TS38 .300 (see section 9.2.3.2) may be performed.

(2) Functional Block Configuration of Radio Communication System Next, the functional block configuration of the radio communication system 10 will be described. Specifically, functional block configurations of gNB 100 and UE 200 will be described.

Fig. 2 is a functional block configuration diagram of gNB100. FIG. 3 is a functional block configuration diagram of UE200. Note that FIGS. 2 and 3 only show main functional blocks related to the description of the embodiments, and that the gNB 100 and UE 200 have other functional blocks (eg, power supply units, etc.). . 2 and 3 show the functional block configurations of the gNB 100 and UE 200, and please refer to FIG. 9 for the hardware configuration.

(2.1) gNB100
As shown in FIG. 2, the gNB 100 includes a radio communication unit 110, an RRC/Xn processing unit 120, a handover processing unit 130 and a control unit 140.

The radio communication unit 110 transmits downlink signals (DL signals) according to NR. Radio communication section 110 also receives an uplink signal (UL signal) according to NR.

As described above, the cell group may include MCG and SCG. gNB100 may belong to either MCG or SCG. In other words, the gNB 100 can configure both the MN and the SN.

In addition, in relation to handover of UE 200, gNB 100 may configure the source radio base station of the handover source, or may configure the target radio base station of the handover destination (transition destination). When configuring the source radio base station, it may be expressed as S-MN and S-SN depending on whether it is MN or SN.

On the other hand, when configuring the target radio base station, it may be expressed as T-MN and T-SN depending on whether it is MN or SN. Also, in CHO, when there are multiple handover destination candidate cells, they may be expressed as T-MN1, T-MN2, T-SN1, T-SN2, and the like.

The RRC/Xn processing unit 120 executes various processes related to the radio resource control layer (RRC) and the Xn interface. Specifically, RRC/Xn processing section 120 can transmit RRC Reconfiguration to UE 200 . Also, the RRC/Xn processing unit 120 can receive RRC Reconfiguration Complete, which is a response to RRC Reconfiguration, from the UE 200 .

Also, the RRC/Xn processing unit 120 may transmit and receive various messages with other gNBs 100 via the Xn interface. The message may include a message regarding handover of UE 200 (which may include CHO) and a message regarding setting of a cell group.

In the case of a radio base station that supports LTE (Evolved Universal Terrestrial Radio Access Network (E-UTRAN)), an X2 interface may be used instead of Xn. Alternatively, the Xn and X2 interfaces may be used together.

Specifically, the RRC/Xn processing unit 120 may receive a handover abort message from the source radio base station. In this embodiment, the RRC/Xn processing unit 120 may constitute a receiving unit. More specifically, RRC/Xn processing section 120 may receive a handover cancel message (HO cancel) when gNB 100 forms a T-MN.

HO cancel may be sent by S-MN and used to cancel the CHO of UE 200.

Also, the RRC/Xn processing unit 120 may transmit a target radio base station release request message to the target radio base station within the cell group. In this embodiment, the RRC/Xn processing unit 120 may configure a transmitting unit that transmits release request messages.

Specifically, when the gNB 100 configures the T-MN, the RRC/Xn processing unit 120 may transmit an S-node Release request to the target cell (gNB) included in the SCG. More specifically, the RRC/Xn processing unit 120 may send an S-node Release request containing the reason for the release request to the T-SN. The reason for the release request may be that CHO was canceled or CHO to another candidate cell was completed.

Also, the RRC/Xn processing unit 120 may transmit a release required message of its own station to the target radio base station within the cell group. In this embodiment, the RRC/Xn processing unit 120 may configure a transmitting unit that transmits a release required message.

Specifically, when the gNB 100 configures the T-SN, the RRC/Xn processing unit 120 sends an S-node Release required to the T-MN in the MCG indicating that the T-SN needs to be released. can be sent.

The RRC/Xn processing unit 120 may transmit S-node Release required to the T-MN according to timer expiration or the state of radio resources in its own station. A timer may be started at the timing of adding or changing an SN (which may be expressed as an S-node), and for example, T_Dcoverall, TXn_Dcoverall, etc. may be used. In particular, in the present embodiment, it may be interpreted as a timer that is started at the timing of adding an SN that can be applied to CHO and that measures a predetermined time. In the following, it may be expressed as T_Dcoverall_CHO, TXn_Dcoverall_CHO, etc. for convenience.

The handover processing unit 130 executes processing related to handover of the UE200. Specifically, handover processing section 130 can perform processing related to normal handover of UE 200 (which may be referred to as legacy handover) and conditional handover (CHO).

In particular, regarding CHO, the transition destination cell may constitute MCG and SCG. Such CHO may also be referred to as CHO with SCG configuration.

The control unit 140 controls each functional block that configures the gNB100. In particular, in the present embodiment, the control unit 140 can perform control related to RRC inter-node messages regarding CHO and timers for CHO.

Specifically, the control unit 140 may control HO-related messages transmitted and received between the source radio base station and the target radio base station, and messages related to SN (SgNB) addition, change, and release. .

Also, the control unit 140 may control a timer for CHO. Specifically, the control unit 140 may control T_Dcoverall_CHO and TXn_Dcoverall_CHO that are started at the timing of adding an SN or the like.

(2.2) UE200
As shown in FIG. 3 , UE 200 includes radio communication section 210 , RRC processing section 220 , handover execution section 230 and control section 240 .

The radio communication unit 210 transmits an uplink signal (UL signal) according to NR. Also, the radio communication unit 210 receives an uplink signal (DL signal) according to NR.

The wireless communication unit 210 supports dual connectivity (DC), and can connect to multiple gNBs 100 at the same time to transmit and receive wireless signals (which may be read as component carriers, etc.). That is, radio communication section 210 can perform communication simultaneously with gNB 100 belonging to MCG or SCG.

The RRC processing unit 220 executes various processes in the radio resource control layer (RRC). Specifically, the RRC processing unit 220 can transmit and receive radio resource control layer messages. In this embodiment, the RRC processing unit 220 may constitute a receiving unit that receives messages of the radio resource control layer.

The RRC processing unit 220 can receive RRC Reconfiguration from the network, specifically from the NG-RAN 20. Also, the RRC processing unit 220 can transmit RRC Reconfiguration Complete, which is a response to RRC Reconfiguration, to the network.

Also, when CHO with a specific target radio base station fails and another candidate cell is selected in the reconnection procedure, the RRC processing unit 220 transmits a setting request only to the primary cell (PCell). good too. In this embodiment, the RRC processing unit 220 may constitute a transmitting unit that transmits a setting request.

Specifically, when CHO fails and other candidate cells (PCell and PSCell may be included) are selected, the RRC processing unit 220 may transmit a response to the RRC setting request only to the PCell. Specifically, RRC processing section 220 may apply reconfiguration in RRC (RRC Reconfiguration) and transmit RRC Reconfiguration Complete, which is a response to RRC Reconfiguration, to the T-MN forming the PCell. Note that RRC Reconfiguration Complete may be interpreted as a message indicating that RRC Reconfiguration has been applied.

Alternatively, the RRC processing unit 220 may transmit the configuration request to PCell and SCell (PSCell may be included).

In addition, when CHO fails, RRC processing section 220 fails for either or both of a primary cell (PCell) and a secondary cell (SCell (which may include PSCell)) among a plurality of candidate cells. A report may be sent containing information indicating that the In this embodiment, the RRC processing unit 220 may configure a transmitting unit that transmits a report including CHO failure information.

Specifically, when the CHO with SCG configuration fails, the RRC processing unit 220 may send a Radio Link Failure (RLF) report including information indicating the failure to the network.

The RLF report may include information when the first CHO fails, and information when the second and subsequent CHOs fail. In addition, the RLF report may include information indicating with which cell CHO has failed, as described above. CHO failure may be determined by whether the Random Access (RA) procedure is successful or simply whether the Random Access Channel (RACH) transmission is successful. Failure of RACH may be simply called connection failure or the like, or may be expressed as failedTargetPCell or failedTargetPSCell.

　The second and subsequent CHO failures may be determined based on a specific timer. For example, the RRC processing unit 220 starts at the start of the RRC connection re-establishment procedure and stops when a suitable NR cell or a cell using another radio access technology (RAT) is selected. CHO failure may be determined.

　In addition, CHO information about SCell may be included in, for example, SCG Failure Information instead of RLF report.

The handover execution unit 230 executes handover of the UE200. Specifically, the handover execution unit 230 can execute processing related to normal handover (legacy handover) and conditional handover (CHO).

In the case of CHO, the handover execution unit 230 may transition to a candidate cell when an execution condition is satisfied. The execution condition may be determined based on the quality of the reference signal (RS), specifically the value of RSRP, RSRQ, or SINR, as described above.

　In addition, the transition destination of CHO may not be accompanied by SCG, or may be accompanied by SCG (CHO with SCG configuration). In other words, a transition destination cell by CHO may be a single cell, or may be composed of a plurality of cells (which may be read as a cell group) according to DC.

The control unit 240 controls each functional block that configures the UE200. In particular, in the present embodiment, the control unit 240 may control execution of conditional handover (CHO), more specifically, control execution of CHO with SCG configuration.

Regarding CHO with SCG configuration, if the CHO fails, the control unit 240 can control selection of other candidate cells.

For example, when the first CHO fails and another candidate cell is selected, control section 240 transmits an RRC configuration request (for example, RRC Reconfiguration) only to PCell among the other candidate cells. can be controlled to

Alternatively, when the first CHO fails and another candidate cell is selected, the control unit 240 transmits the configuration request to both the PCell and SCell (PSCell may be included) of the other candidate cell. can be controlled as follows.

In addition, regarding CHO with SCG configuration, if the CHO fails, the control unit 240 may control to transmit a report (RLF report) including information on the cell group.

For example, if the CHO with SCG configuration fails, the control unit 240 generates an RLF report containing information indicating that one or both of the PCell and SCell among the plurality of candidate cells have failed. You can control it.

In addition, the RLF report may further include at least one of identification information, quality information, time information, activation status, etc. regarding the failed cell. The activation state may include an indication that the SCG is deactivated.

(3) Operation of Radio Communication System Next, the operation of the radio communication system 10 will be described. Specifically, conditional handover (CHO), particularly when handover candidate cells constitute a cell group, specifically, CHO (CHO with SCG configuration) when the candidate cells constitute an SCG will be described.

(3.1) Operation example 1
In the CHO with SCG configuration, in determining whether or not the execution condition is satisfied (which may be called CHO condition evaluation), the Source PCell cancels handover to the Target PCell that does not satisfy the execution condition. You can send a message, specifically HO cancel.

Also, the Target PCell (which may be expressed as T-MN) can send an S-node Release request to the Target SCell (which may be expressed as T-SN) in response to HO cancel. In this operational example, the S-node Release request may include the reason for canceling the handover.

FIG. 4 shows a sequence example (part 1) of CHO with SCG configuration according to operation example 1. As shown in FIG. 4, S-MN, S-SN, T-MN1, 2 and T-SN can perform operations related to addition of SCG (SgNB) in response to a handover request (HO request).

This sequence is specified in 3GPP TS38.300 Chapter 9.2.3.2 (CHO related) and 3GPP TS38.423 Chapter 8.3.1. Although only one T-SN is shown in FIG. 4, there may be two or more T-SNs (same below).

Specifically, after receiving HO cancel from Source PCell (which may be expressed as S-MN), Target PCell (T-MN2), which is a candidate for CHO, sends SgNB addition request to T-SN. When sending an S-node Release request, the cause value CHO/HO cancel may be included in the S-node Release request.

Alternatively, the T-SN that has received the SgNB addition request uses a timer to adjust the timing of sending the S-node Release required indicating that the T-SN needs to be released to the Target PCell (T-MN2). may

FIG. 5 shows a sequence example (part 2) of CHO with SCG configuration according to operation example 1. As shown in FIG. 5, the T-SN may newly provide T_Dcoverall_CHO and TXn_Dcoverall_CHO (tentative names) as timers for CHO in addition to the existing T_Dcoverall and TXn_Dcoverall.

When TXn_Dcoverall_CHO (or T_Dcoverall_CHO, hereinafter the same) expires, T-SN may trigger S-NG-RAN node initiated S-NG-RAN node Release procedure and send S-node Release required.

In addition, T-SN may include cause value (timer T_Dcoverall_CHO/TXn_Dcoverall_CHO expiry) indicating that TXn_Dcoverall_CHO has expired in S-node Release required. TXn_Dcoverall_CHO may be used for NR (Xn interface), and T_Dcoverall_CHO may be used for LTE (X2 interface).

Alternatively, if T-SN runs out of radio resources for T-SN before TXn_Dcoverall_CHO expires, it triggers S-NG-RAN node initiated S-NG-RAN node Release procedure and S-node Release required. You may send. The radio resource related to the T-SN may be a radio resource within the SN (radio base station), or may be a radio resource used by other nodes connected to the SN and indirectly affected.

In addition, the T-SN may include a cause value (no radio resource available for CHO) indicating the lack of radio resources in the S-node Release required.

Note that the S-NG-RAN node initiated S-NG-RAN node Release procedure may also be triggered by a lack of T-SN radio resources, as described above, so it may be executed before TXn_Dcoverall_CHO expires. you can

(3.2) Operation example 2
In the CHO with SCG configuration, it is assumed that timer T311 starts and UE 200 performs cell reselection after CHO fails to synchronize with a candidate cell. Synchronization with a candidate cell may be read as connection or setting with a candidate cell. Typically, it may be interpreted as an unsuccessful RACH transmission, as described above.

In this operation example, when UE 200 selects another CHO candidate cell, UE 200 may select the selected cell and transmit an RRC configuration request (for example, RRC Reconfiguration). The RRC configuration request may be RRC Reconfiguration Complete or another RRC message.

Also, T311 may be started at the beginning of the RRC connection re-establishment procedure, and stopped when a suitable NR cell or a cell using another radio access technology (RAT) is selected, as described above.

FIG. 6 shows a sequence example (part 1) of CHO with SCG configuration according to operation example 2. As shown in FIG. 6, when UE 200 fails to synchronize with a candidate cell (RACH transmission fails) and selects another CHO candidate cell, both Target PCell and Target SCell (PSCell) are RRC Reconfiguration may be applied (which may be translated as transmission) (option 1).

Alternatively, when synchronization with a candidate cell fails (RACH transmission fails) and another CHO candidate cell is selected, UE 200 applies RRC Reconfiguration to only one candidate cell (it may be translated as transmission). Good (option 2).

Also, after receiving the configuration request (for example, RRC Reconfiguration Complete), the Target PCell (T-MN2) may transmit SN Reconfiguration Complete to T-SN. Also, T-MN2 may send SN Reconfiguration Complete to another T-SN (eg, T-SN2).

FIG. 7 shows a sequence example (part 2) of CHO with SCG configuration according to operation example 2. As shown in FIG. 7, UE 200 may apply RRC Reconfiguration only to Target PCell. This is because the PSCell may have already been released compared to the PCell.

(3.3) Operation example 3
UE200 may transmit RLF report as follows, when CHO with SCG configuration fails. FIG. 8 shows a sequence example of a CHO with SCG configuration according to operation example 3. FIG.

For example, in the first CHO, if synchronization with both Target PCell and Target SCell (PSCell) fails (CHO First failure, Failure 1 in FIG. 8), the failed Target PCell ID, Target SCell ID, PCell /PSCell (serving cell) quality, PCell/PSCell neighbor cell quality, candidate Target PCell ID/quality MAY be included in the RLF report.

On the other hand, the UE 200 succeeds in synchronization with the Target PCell in the first CHO, but when synchronization with the Target SCell (PSCell) fails, the Target PCell ID for which synchronization was successful, the Target SCell ID for which synchronization failed, PCell/PSCell (serving cell) quality, PCell/PSCell neighbor cell quality, candidate Target PCell ID/quality may be included in the RLF report or SCG Failure Information.

Also, after the CHO First failure, the UE 200 executes cell reselection during activation (operation) of T311, and applies a configuration request (RRC Reconfiguration) to the selected candidate PSCell (that is, the second time CHO), may operate according to either:

UE 200 fails in synchronization with both Target PCell and Target SCell (PSCell) in the second CHO (CHO Second failure, Failure 2 in FIG. 8) as well as CHO First failure Target PCell ID, Target SCell ID, PCell/PSCell (serving cell) quality, PCell/PSCell neighbor cell quality, candidate Target PCell ID/quality MAY be included in the RLF report. In this case, information related to the first failure may also be included.

On the other hand, the UE 200 succeeds in synchronization with the Target PCell in the second CHO, but if synchronization with the Target SCell (PSCell) fails, similar to CHO First failure, the Target PCell ID with which synchronization was successful, Target SCell ID, PCell/PSCell (serving cell) quality, PCell/PSCell neighbor cell quality, candidate Target PCell ID/quality for which synchronization failed may be included in the RLF report or SCG Failure Information. Also in this case, information related to the first failure may be further included.

Also, when the SCG related to CHO is in an inactive state (deactivated state), an indication indicating that the SCG is in a deactivated state may be included.

(4) Functions and Effects According to the above-described embodiment, the following functions and effects are obtained. Specifically, the gNB 100 (T-MN) can send an S-node Release request containing the reason for the release request to the T-SN.

In addition, the gNB 100 (T-SN) can transmit S-node Release required to the T-MN according to the expiration of a timer (eg, TXn_Dcoverall_CHO) or the state of radio resources in its own station.

When CHO fails and other candidate cells (PCell and PSCell may be included) are selected, the UE 200 can send an RRC setup request to only the PCell or to the PCell and PSCell.

Therefore, the gNB 100 and UE 200 can realize proper operation when handover by CHO with SCG configuration fails.

More specifically, in CHO with SCG configuration, the procedures for releasing SNs that were not targeted by CHO and the method of applying RRC Reconfiguration to candidate target cells after CHO First failure have been clarified. can be realized more reliably.

In addition, since RLF reports (SCG Failure Information) regarding CHO First failure and CHO Second failure can be reported, it can contribute to the optimization of settings (parameters) related to CHO with SCG configuration.

(5) Other Embodiments Although the embodiments have been described above, it is obvious to those skilled in the art that the present invention is not limited to the description of the embodiments, and that various modifications and improvements are possible.

For example, although conditional handover (CHO) has been described as an example in the above-described embodiments, similar operations are applied to other similar operations, such as conditional SCG change. good too. In this case, the cell may be read as a cell group or the like.

Also, the terms primary cell and secondary cell may be replaced with other synonymous terms, such as state cell, sub cell, first cell, second cell, master, sub, and the like.

Also, in the above description, configure, activate, update, indicate, enable, specify, and select may be read interchangeably. good. Similarly, link, associate, correspond, and map may be read interchangeably to allocate, assign, monitor. , map, may also be read interchangeably.

Furthermore, specific, dedicated, UE-specific, and UE-specific may be read interchangeably. Similarly, common, shared, group-common, UE common, and UE shared may be read interchangeably.

Also, the block configuration diagrams (FIGS. 2 and 3) used to describe the above-described embodiment show blocks in units of functions. These functional blocks (components) are realized by any combination of at least one of hardware and software. Also, the method of implementing each functional block is not particularly limited. That is, each functional block may be implemented using one device physically or logically coupled, or directly or indirectly using two or more physically or logically separate devices (e.g. , wired, wireless, etc.) and may be implemented using these multiple devices. A functional block may be implemented by combining software in the one device or the plurality of devices.

Functions include judging, determining, determining, calculating, calculating, processing, deriving, investigating, searching, checking, receiving, transmitting, outputting, accessing, resolving, selecting, choosing, establishing, comparing, assuming, expecting, assuming, Broadcasting, notifying, communicating, forwarding, configuring, reconfiguring, allocating, mapping, assigning, etc. can't For example, a functional block (component) that performs transmission is called a transmitting unit or transmitter. In either case, as described above, the implementation method is not particularly limited.

Furthermore, the gNB 100 and UE 200 (applicable device) described above may function as a computer that performs processing of the wireless communication method of the present disclosure. FIG. 9 is a diagram showing an example of the hardware configuration of the device. As shown in FIG. 9, the device may be configured as a computing device including a processor 1001, a memory 1002, a storage 1003, a communication device 1004, an input device 1005, an output device 1006, a bus 1007, and the like.

In the following explanation, the term "apparatus" can be read as a circuit, device, unit, or the like. The hardware configuration of the device may be configured to include one or more of each device shown in the figure, or may be configured without some of the devices.

Each functional block of the device (see Fig. 2.3) is realized by any hardware element of the computer device or a combination of the hardware elements.

In addition, each function of the device is implemented by causing the processor 1001 to perform calculations, controlling communication by the communication device 1004, and controlling the It is realized by controlling at least one of data reading and writing in 1002 and storage 1003 .

A processor 1001, for example, operates an operating system and controls the entire computer. The processor 1001 may be configured with a central processing unit (CPU) including interfaces with peripheral devices, a controller, arithmetic units, registers, and the like.

Also, the processor 1001 reads programs (program codes), software modules, data, etc. from at least one of the storage 1003 and the communication device 1004 to the memory 1002, and executes various processes according to them. As the program, a program that causes a computer to execute at least part of the operations described in the above embodiments is used. Further, the various processes described above may be executed by one processor 1001, or may be executed by two or more processors 1001 simultaneously or sequentially. Processor 1001 may be implemented by one or more chips. Note that the program may be transmitted from a network via an electric communication line.

The memory 1002 is a computer-readable recording medium, and is composed of at least one of Read Only Memory (ROM), Erasable Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), Random Access Memory (RAM), etc. may be The memory 1002 may also be called a register, cache, main memory (main storage device), or the like. The memory 1002 can store programs (program code), software modules, etc. capable of executing a method according to an embodiment of the present disclosure.

The storage 1003 is a computer-readable recording medium, for example, an optical disc such as a Compact Disc ROM (CD-ROM), a hard disk drive, a flexible disc, a magneto-optical disc (for example, a compact disc, a digital versatile disc, a Blu-ray disk), smart card, flash memory (eg, card, stick, key drive), floppy disk, magnetic strip, and/or the like. Storage 1003 may also be referred to as an auxiliary storage device. The recording medium described above may be, for example, a database, server, or other suitable medium including at least one of memory 1002 and storage 1003 .

The communication device 1004 is hardware (transmitting/receiving device) for communicating between computers via at least one of a wired network and a wireless network, and is also called a network device, a network controller, a network card, a communication module, or the like.

The communication device 1004 includes a high-frequency switch, duplexer, filter, frequency synthesizer, etc., for realizing at least one of frequency division duplex (FDD) and time division duplex (TDD). may consist of

The input device 1005 is an input device (for example, keyboard, mouse, microphone, switch, button, sensor, etc.) that receives input from the outside. The output device 1006 is an output device (eg, display, speaker, LED lamp, etc.) that outputs to the outside. Note that the input device 1005 and the output device 1006 may be integrated (for example, a touch panel).

Also, each device such as the processor 1001 and the memory 1002 is connected by a bus 1007 for communicating information. The bus 1007 may be configured using a single bus, or may be configured using different buses between devices.

In addition, the device includes hardware such as a microprocessor, digital signal processor (DSP), application specific integrated circuit (ASIC), programmable logic device (PLD), field programmable gate array (FPGA), etc. A part or all of each functional block may be implemented by the hardware. For example, processor 1001 may be implemented using at least one of these pieces of hardware.

In addition, notification of information is not limited to the aspects/embodiments described in the present disclosure, and may be performed using other methods. For example, the notification of information may include physical layer signaling (e.g., Downlink Control Information (DCI), Uplink Control Information (UCI), higher layer signaling (e.g., RRC signaling, Medium Access Control (MAC) signaling, broadcast information (Master Information Block (MIB), System Information Block (SIB), other signals, or combinations thereof, and RRC signaling may also be referred to as RRC messages, e.g., RRC Connection Setup ) message, RRC Connection Reconfiguration message, or the like.

Each aspect/embodiment described in this disclosure includes Long Term Evolution (LTE), LTE-Advanced (LTE-A), SUPER 3G, IMT-Advanced, 4th generation mobile communication system (4G), 5th generation mobile communication system ( 5G), Future Radio Access (FRA), New Radio (NR), W-CDMA (registered trademark), GSM (registered trademark), CDMA2000, Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi (registered trademark)) , IEEE 802.16 (WiMAX®), IEEE 802.20, Ultra-WideBand (UWB), Bluetooth®, other suitable systems, and/or next-generation systems enhanced therefrom. may be applied to Also, a plurality of systems may be applied in combination (for example, a combination of at least one of LTE and LTE-A and 5G).

The order of the processing procedures, sequences, flowcharts, etc. of each aspect/embodiment described in the present disclosure may be changed as long as there is no contradiction. For example, the methods described in this disclosure present elements of the various steps using a sample order, and are not limited to the specific order presented.

A specific operation that is performed by a base station in the present disclosure may be performed by its upper node in some cases. In a network consisting of one or more network nodes with a base station, various operations performed for communication with a terminal may be performed by the base station and other network nodes other than the base station (e.g. MME or S-GW, etc., but not limited to). Although the case where there is one network node other than the base station is exemplified above, it may be a combination of a plurality of other network nodes (for example, MME and S-GW).

Information, signals (information, etc.) can be output from a higher layer (or a lower layer) to a lower layer (or a higher layer). It may be input and output via multiple network nodes.

Input/output information may be stored in a specific location (for example, memory) or managed using a management table. Input and output information may be overwritten, updated, or appended. The output information may be deleted. The entered information may be transmitted to other devices.

The determination may be made by a value represented by one bit (0 or 1), by a true/false value (Boolean: true or false), or by numerical comparison (for example, a predetermined value).

Each aspect/embodiment described in the present disclosure may be used alone, may be used in combination, or may be used by switching along with execution. In addition, the notification of predetermined information (for example, notification of “being X”) is not limited to being performed explicitly, but may be performed implicitly (for example, not notifying the predetermined information). good too.

Software, whether referred to as software, firmware, middleware, microcode, hardware description language or otherwise, includes instructions, instruction sets, code, code segments, program code, programs, subprograms, and software modules. , applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, and the like.

In addition, software, instructions, information, etc. may be transmitted and received via a transmission medium. For example, the Software uses wired technology (coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL), etc.) and/or wireless technology (infrared, microwave, etc.) to access websites, Wired and/or wireless technologies are included within the definition of transmission medium when sent from a server or other remote source.

The information, signals, etc. described in this disclosure may be represented using any of a variety of different technologies. For example, data, instructions, commands, information, signals, bits, symbols, chips, etc. that may be referred to throughout the above description may refer to voltages, currents, electromagnetic waves, magnetic fields or magnetic particles, light fields or photons, or any of these. may be represented by a combination of

The terms explained in this disclosure and terms necessary for understanding this disclosure may be replaced with terms having the same or similar meanings. For example, the channel and/or symbols may be signaling. A signal may also be a message. A component carrier (CC) may also be called a carrier frequency, a cell, a frequency carrier, or the like.

The terms "system" and "network" used in this disclosure are used interchangeably.

In addition, the information, parameters, etc. described in the present disclosure may be expressed using absolute values, may be expressed using relative values from a predetermined value, or may be expressed using other corresponding information. may be represented. For example, radio resources may be indexed.

The names used for the parameters described above are not restrictive names in any respect. Further, the formulas, etc., using these parameters may differ from those expressly disclosed in this disclosure. Since the various channels (e.g., PUCCH, PDCCH, etc.) and information elements can be identified by any suitable designation, the various designations assigned to these various channels and information elements are in no way restrictive designations. is not.

In the present disclosure, "base station (BS)", "radio base station", "fixed station", "NodeB", "eNodeB (eNB)", "gNodeB (gNB)", " "access point", "transmission point", "reception point", "transmission/reception point", "cell", "sector", "cell group", " Terms such as "carrier", "component carrier" may be used interchangeably. A base station may also be referred to by terms such as macrocell, small cell, femtocell, picocell, and the like.

A base station can accommodate one or more (eg, three) cells (also called sectors). When a base station accommodates multiple cells, the overall coverage area of the base station can be partitioned into multiple smaller areas, each smaller area corresponding to a base station subsystem (e.g., a small indoor base station (Remote Radio)). Head: RRH) can also provide communication services.

The term "cell" or "sector" refers to part or all of the coverage area of at least one of a base station and base station subsystem that provides communication services in this coverage.

In this disclosure, terms such as "Mobile Station (MS)", "user terminal", "User Equipment (UE)", "terminal" may be used interchangeably. .

A mobile station is defined by those skilled in the art as a subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless It may also be called a terminal, remote terminal, handset, user agent, mobile client, client, or some other suitable term.

At least one of the base station and mobile station may be called a transmitting device, a receiving device, a communication device, or the like. At least one of the base station and the mobile station may be a device mounted on a mobile object, the mobile object itself, or the like. The mobile body may be a vehicle (e.g., car, airplane, etc.), an unmanned mobile body (e.g., drone, self-driving car, etc.), or a robot (manned or unmanned ). Note that at least one of the base station and the mobile station includes devices that do not necessarily move during communication operations. For example, at least one of the base station and mobile station may be an Internet of Things (IoT) device such as a sensor.

Also, the base station in the present disclosure may be read as a mobile station (user terminal, hereinafter the same). For example, communication between a base station and a mobile station is replaced with communication between multiple mobile stations (for example, Device-to-Device (D2D), Vehicle-to-Everything (V2X), etc.) Regarding the configuration, each aspect/embodiment of the present disclosure may be applied. In this case, the mobile station may have the functions that the base station has. Also, words such as "up" and "down" may be replaced with words corresponding to inter-terminal communication (for example, "side"). For example, uplink channels, downlink channels, etc. may be read as side channels.

Similarly, mobile stations in the present disclosure may be read as base stations. In this case, the base station may have the functions that the mobile station has.
A radio frame may consist of one or more frames in the time domain. Each frame or frames in the time domain may be referred to as a subframe. A subframe may also consist of one or more slots in the time domain. A subframe may be a fixed time length (eg, 1 ms) independent of numerology.

A numerology may be a communication parameter that applies to the transmission and/or reception of a signal or channel. Numerology, for example, subcarrier spacing (SCS), bandwidth, symbol length, cyclic prefix length, transmission time interval (TTI), number of symbols per TTI, radio frame structure, transmission and reception specific filtering operations performed by the receiver in the frequency domain, specific windowing operations performed by the transceiver in the time domain, and/or the like.

A slot may consist of one or more symbols (Orthogonal Frequency Division Multiplexing (OFDM) symbols, Single Carrier Frequency Division Multiple Access (SC-FDMA) symbols, etc.) in the time domain. A slot may be a unit of time based on numerology.

A slot may contain multiple mini-slots. Each minislot may consist of one or more symbols in the time domain. A minislot may also be referred to as a subslot. A minislot may consist of fewer symbols than a slot. A PDSCH (or PUSCH) that is transmitted in time units larger than a minislot may be referred to as PDSCH (or PUSCH) mapping type A. PDSCH (or PUSCH) transmitted using minislots may be referred to as PDSCH (or PUSCH) mapping type B.

Radio frames, subframes, slots, minislots and symbols all represent time units when transmitting signals. Radio frames, subframes, slots, minislots and symbols may be referred to by other corresponding designations.

For example, one subframe may be called a transmission time interval (TTI), multiple consecutive subframes may be called a TTI, and one slot or one minislot may be called a TTI. That is, at least one of the subframe and TTI may be a subframe (1ms) in existing LTE, may be a period shorter than 1ms (eg, 1-13 symbols), or a period longer than 1ms may be Note that the unit representing the TTI may be called a slot, minislot, or the like instead of a subframe.

Here, TTI refers to, for example, the minimum scheduling time unit in wireless communication. For example, in the LTE system, a base station performs scheduling to allocate radio resources (frequency bandwidth, transmission power, etc. that can be used by each user terminal) to each user terminal on a TTI basis. Note that the definition of TTI is not limited to this.

The TTI may be a transmission time unit for channel-encoded data packets (transport blocks), code blocks, codewords, etc., or may be a processing unit for scheduling, link adaptation, etc. Note that when a TTI is given, the time interval (for example, the number of symbols) in which transport blocks, code blocks, codewords, etc. are actually mapped may be shorter than the TTI.

If one slot or one minislot is called a TTI, one or more TTIs (that is, one or more slots or one or more minislots) may be the minimum scheduling time unit. Also, the number of slots (the number of mini-slots) constituting the minimum time unit of the scheduling may be controlled.

A TTI with a time length of 1 ms may be called a normal TTI (TTI in LTE Rel.8-12), normal TTI, long TTI, normal subframe, normal subframe, long subframe, slot, etc. A TTI that is shorter than a regular TTI may also be called a shortened TTI, a short TTI, a partial or fractional TTI, a shortened subframe, a short subframe, a minislot, a subslot, a slot, and so on.

In addition, long TTI (for example, normal TTI, subframe, etc.) may be read as TTI having a time length exceeding 1 ms, and short TTI (for example, shortened TTI, etc.) is less than the TTI length of long TTI and 1 ms. A TTI having a TTI length greater than or equal to this value may be read as a replacement.

A resource block (RB) is a resource allocation unit in the time domain and frequency domain, and may include one or more consecutive subcarriers in the frequency domain. The number of subcarriers included in an RB may be the same regardless of neurology, and may be 12, for example. The number of subcarriers included in an RB may be determined based on neumerology.

Also, the time domain of an RB may include one or more symbols and may be 1 slot, 1 minislot, 1 subframe, or 1 TTI long. One TTI, one subframe, etc. may each consist of one or more resource blocks.

One or more RBs are physical resource blocks (Physical RB: PRB), sub-carrier groups (SCG), resource element groups (REG), PRB pairs, RB pairs, etc. may be called.

In addition, a resource block may be composed of one or more resource elements (Resource Element: RE). For example, 1 RE may be a radio resource region of 1 subcarrier and 1 symbol.

A Bandwidth Part (BWP) (which may also be called a Bandwidth Part) represents a subset of contiguous common resource blocks (RBs) for a neumerology in a carrier. good. Here, the common RB may be identified by an RB index based on the common reference point of the carrier. PRBs may be defined in a BWP and numbered within that BWP.

BWP may include BWP for UL (UL BWP) and BWP for DL (DL BWP). One or more BWPs may be configured in one carrier for a UE.

At least one of the configured BWPs may be active, and the UE may not expect to transmit or receive a given signal/channel outside the active BWP. Note that "cell", "carrier", etc. in the present disclosure may be read as "BWP".

The structures such as radio frames, subframes, slots, minislots and symbols described above are only examples. For example, the number of subframes included in a radio frame, the number of slots per subframe or radio frame, the number of minislots included in a slot, the number of symbols and RBs included in a slot or minislot, the number of Configurations such as the number of subcarriers and the number of symbols in a TTI, symbol length, cyclic prefix (CP) length, etc. can be varied.

The terms "connected," "coupled," or any variation thereof mean any direct or indirect connection or coupling between two or more elements, It can include the presence of one or more intermediate elements between two elements being "connected" or "coupled." Couplings or connections between elements may be physical, logical, or a combination thereof. For example, "connection" may be read as "access". As used in this disclosure, two elements are defined using at least one of one or more wires, cables and printed electrical connections and, as some non-limiting and non-exhaustive examples, in the radio frequency domain. , electromagnetic energy having wavelengths in the microwave and light (both visible and invisible) regions, and the like.

The reference signal can also be abbreviated as Reference Signal (RS), and may also be called Pilot depending on the applicable standard.

The term "based on" as used in this disclosure does not mean "based only on" unless otherwise specified. In other words, the phrase "based on" means both "based only on" and "based at least on."

"Means" in the configuration of each device described above may be replaced with "unit", "circuit", "device", or the like.

Any reference to elements using the "first," "second," etc. designations used in this disclosure does not generally limit the quantity or order of those elements. These designations may be used in this disclosure as a convenient method of distinguishing between two or more elements. Thus, references to first and second elements do not imply that only two elements may be employed therein or that the first element must precede the second element in any way.

Where "include," "including," and variations thereof are used in this disclosure, these terms are inclusive, as is the term "comprising." is intended. Furthermore, the term "or" as used in this disclosure is not intended to be an exclusive OR.

In this disclosure, if articles are added by translation, such as a, an, and the in English, the disclosure may include that the nouns following these articles are plural.

The terms "determining" and "determining" used in this disclosure may encompass a wide variety of actions. "Judgement" and "determination" are, for example, judging, calculating, computing, processing, deriving, investigating, looking up, searching, inquiring (eg, lookup in a table, database, or other data structure), ascertaining as "judged" or "determined", and the like. Also, "judgment" and "determination" are used for receiving (e.g., receiving information), transmitting (e.g., transmitting information), input, output, access (accessing) (for example, accessing data in memory) may include deeming that a "judgment" or "decision" has been made. In addition, "judgment" and "decision" are considered to be "judgment" and "decision" by resolving, selecting, choosing, establishing, comparing, etc. can contain. In other words, "judgment" and "decision" can include considering that some action is "judgment" and "decision". Also, "judgment (decision)" may be read as "assuming", "expecting", "considering", or the like.

In the present disclosure, the term "A and B are different" may mean "A and B are different from each other." The term may also mean that "A and B are different from C". Terms such as "separate," "coupled," etc. may also be interpreted in the same manner as "different."

Although the present disclosure has been described in detail above, it is clear to those skilled in the art that the present disclosure is not limited to the embodiments described in the present disclosure. The present disclosure can be practiced with modifications and variations without departing from the spirit and scope of the present disclosure as defined by the claims. Accordingly, the description of the present disclosure is for illustrative purposes and is not meant to be limiting in any way.

10 Radio communication system 20 NG RAN
100 gNB
110 radio communication unit 120 RRC/Xn processing unit 130 handover processing unit 140 control unit 200 UE
210 wireless communication unit 220 RRC processing unit 230 CHO execution unit 240 control unit 1001 processor 1002 memory 1003 storage 1004 communication device 1005 input device 1006 output device 1007 bus

Claims (6)

1. a receiving unit for receiving a handover abort message from a source radio base station;
   a transmitting unit configured to transmit a target radio base station release request message to a target radio base station within a cell group;
   A radio base station, wherein the transmitting unit transmits the release request message including a reason for the release request.
2. a transmission unit that transmits a release required message of the own station to the target radio base station in the cell group;
   A control unit that controls a timer for conditional handover,
   The radio base station, wherein the transmission unit transmits the release-required message according to the expiration of the timer or the state of radio resources in the local station.
3. a controller for controlling execution of a conditional handover;
   and a transmitter configured to transmit a response to a configuration request only to a primary cell when the conditional handover fails and another candidate cell is selected.
4. The terminal according to claim 3, wherein the transmission unit transmits a response to the setting request to the primary cell and the secondary cell.
5. a controller for controlling execution of a conditional handover;
   and a transmitting unit configured to transmit a report including information indicating failure to one or both of a primary cell and a secondary cell among candidate cells when the conditional handover fails.
6. receiving a handover abort message from the source radio base station;
   sending a target radio base station release request message to a target radio base station within a cell group;
   The wireless communication method, in the transmitting step, transmitting the release request message including a handover abort reason.

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