JP6228872B2 - COMMUNICATION DEVICE, COMMUNICATION METHOD, AND PROGRAM - Google Patents

Description

  The present invention relates to a control technique for a wireless communication system.

  In recent years, in E-UTRAN (Evolved Universal Terrestrial Radio Access Network), two or more base stations (eNodeB, hereinafter referred to as eNB) are used in a radio terminal apparatus (User Equipment) by U / C separation in a layer higher than the MAC layer. Hereinafter, Dual Connectivity, which is a technique for connecting to UE, is being discussed.

  Dual Connectivity is a technique that can improve the reliability and throughput of communication even in a place where a so-called ideal backhaul environment where a delay is difficult to occur, as represented by an optical fiber, cannot be expected.

  In Dual Connectivity communication, as a base station connected to a UE, there are two master and secondary base stations (MeNB (Master eNB) and SeNB (Secondary eNB)) having a master-slave relationship. Here, the MeNB and the SeNB are connected via a path called “Non-ideal Backhaul” that can cause a delay. The SeNB handles only the U-plane, but the MeNB also controls the C-plane such as generating an RRC message to be transmitted to the UE (see, for example, Non-Patent Documents 1 and 2).

3 gpp TS36.300 Ver. 12.0.0 3 gpp TR36.842 Ver. 12.0.0

  In a conventional wireless communication system in which dual connectivity is formed, an abnormal state (secondary cell group radio link failure, hereinafter referred to as S-RLF) in the radio link between the UE and the SeNB, or due to movement of the UE. If communication quality has deteriorated, such as communication quality deterioration, throughput decrease due to increase in communication volume in the area, even if UE, MeNB, SeNB can recognize the deterioration of communication quality, It took time to process the deterioration of communication quality in the entire wireless communication system. For this reason, there is a case where a delay in recovery of the degradation of the communication quality occurs, which affects the re-establishment of Dual Connectivity, and the data packet for the UE is lost.

  The present invention has been made in view of such problems, and an object thereof is to provide a communication device, a communication method, and a program that can quickly protect a data packet for a UE even when communication quality is deteriorated. There is.

  One embodiment of the present invention relates to a communication device. This communication device is a communication device in a wireless communication system including a master base station and a secondary base station that are in a master-slave relationship with each other, and a terminal device that performs dual connectivity communication between both base stations. Here, one of the plurality of component carriers is set as a primary cell or a secondary cell for communication of the master base station or the secondary base station. Further, uplink and downlink communication is possible in the primary cell, and only downlink communication is possible in the secondary cell. Here, when the communication apparatus detects a deterioration in communication quality in any cell on a radio link between the secondary base station and the terminal apparatus, A storage unit that stores untransmitted data to be transmitted to the terminal device using any of the cells, and when the cell switching process is performed in the control unit, from the untransmitted data stored in the storage unit A transmission unit that reads untransmitted data corresponding to a cell with deteriorated communication quality and transfers the read data to a cell to be switched to.

  According to such an aspect, by transferring untransmitted data corresponding to a cell with deteriorated communication quality to the switching destination cell, it is possible to quickly protect the data packet for the wireless terminal device.

  It should be noted that any combination of the above-described constituent elements and a representation of the present invention converted between a method, an apparatus, a system, a computer program, etc. are also effective as an aspect of the present invention.

  According to the present invention, even when the communication quality deteriorates, the data packet for the UE can be quickly protected.

(Outline of the present invention)
Before describing the embodiments of the present invention, an outline of the present invention will be described first. The present invention is a state in which communication quality such as an abnormal state (S-RLF) that has occurred on a radio link between a secondary base station and a terminal in dual connectivity communication is deteriorated (hereinafter referred to as a communication quality deterioration state). It is related with technology to recover quickly from. The present invention also relates to a technique for quickly protecting data packets for the UE along with recovery.

  In order to quickly restore the communication quality deterioration state, the MeNB needs to recognize the communication quality deterioration state, and then perform processing such as cell change and UE reconfiguration (reconfiguration). Is done. However, even if detected in each of the UE and SeNB, the procedure for reporting to the MeNB is not defined in the standard document, and thus it may take time for the MeNB to recognize the communication quality degradation state.

  In the present invention, when a communication quality degradation state is detected in each of the UE and SeNB, the configuration is such that a report is promptly reported to the MeNB, thereby promptly recovering from the communication quality degradation state. The contents reported to the MeNB include the fact that a communication quality deterioration state has occurred, the generation factor, and the information related to the cell that has been generated so that the resetting for recovery of the communication quality deterioration state can be performed quickly. It was. In addition to resetting for recovery, unsent data buffered for the cell in which the communication quality deterioration state occurs is promptly transferred to the switching destination cell.

The following effects are acquired by the above aspect.
-The details of the communication quality degradation state such as S-RLF can be notified to the MeNB.
-An appropriate action according to the report content from UE or SeNB can be made to perform MeNB.
-SeNB can control the communication quality degradation state on its own secondary cell.
-The UE can quickly recover from the communication quality degradation state.
-Packet loss for the UE can be reduced.
-The service interruption time in the UE can be reduced.

(Configuration example of wireless communication system according to an embodiment of the present invention)
Here, a configuration example of the wireless communication system according to the embodiment of the present invention will be described. FIG. 1 is a diagram illustrating a configuration example of a wireless communication system 100 according to an embodiment of the present invention. The radio communication system 100 includes a MeNB 10, a SeNB 20, and a UE 30.

  Both the MeNB 10 and the SeNB 20 are base station apparatuses. Further, the MeNB 10 and the SeNB 20 are in a master-slave relationship with each other, and the latter belongs to the former. In addition, the MeNB 10 and the SeNB 20 are connected by wire or wirelessly. In FIG. 1, for convenience of illustration, the MeNB 10 is illustrated as a macro base station, and the SeNB 20 is illustrated as a femto base station. However, the present invention can be applied even if the SeNB 20 is also a macro base station. Is easily understood by those skilled in the art.

  MeNB10 implements communication between UE30 using MCG40 (Master Cell Group) which consists of a some component carrier so that it may illustrate. Similarly, SeNB20 implements communication between UE30 using SCG50 (Secondary Cell Group) which consists of a plurality of component carriers. The component carrier is a frequency resource composed of a plurality of subcarriers, and a predetermined number of subcarriers are assigned as one unit, and PCell, Scell, and PScell are allocated as communication resources with the UE 30 as follows. is there.

  In FIG. 1, PCell42 which is the primary cell of MeNB10, and Scell44 which is the secondary cell of MeNB10 are set as MCG40, and the cell 46 becomes NotServingCell to which no cell is assigned to any UE. Moreover, PSCell54 which is the primary cell of SeNB20, and Scell52 which is the secondary cell of SeNB20 are set as SCG50, and NotServingCell56 exists.

  Here, when the primary cell (PCell42, PScell54) is used, the MeNB10 or SeNB20 can perform uplink and downlink communication with the UE30, and when the secondary cell (Scell44, Scell52) is used, Only downlink communication is possible between them.

  In the PCell 42, U-plane and C-plane communication can be performed with the UE 30. On the other hand, in cells other than PCell42, PScell54, Scell44, and Scell52, only U-plane communication is possible with UE30. In FIG. 1, U-plane communication with the UE 30 using the MCG 40 or SCG 50 is illustrated by a solid line arrow, and C-plane communication is illustrated by a broken line arrow. The same applies to the same wireless communication system described later.

(Configuration example of MeNB 10)
FIG. 2 is a diagram illustrating a configuration example of the MeNB 10 of FIG. The MeNB 10 includes a MeNB transmission unit 12, a MeNB control unit 14, and a MeNB storage unit 16.

  The MeNB transmission unit 12 performs radio communication with the UE 30 using a cell set in any component carrier of the MCG 40. In addition, the MeNB transmission unit 12 may perform wired or wireless communication with the SeNB 20. For these wireless communication and wired communication, a known modulation / demodulation technique, antenna technique, or the like may be used. The same applies to the transmission units in SeNB 20 and UE 30 described later.

  The MeNB storage unit 16 stores and manages information to be transmitted to the UE 30 or the SeNB 20.

The MeNB control unit 14 controls communication with the UE 30 or the SeNB 20. In addition, when the MeNB control unit 14 performs dual connectivity communication between the MeNB 10 and the UE 30 or SeNB 20, in particular, information on the communication quality degradation state of any cell on the radio link between the SeNB 20 and the UE 30. When the message is received, an appropriate action, for example, the following processing may be performed according to the received information.
-Setting (Activation / Deactivation), Release (Release), Changing process (Modification) of PCell42 and Scell44 in MSG40, Changing process to new SeNB20-Setting / resetting process for UE30 (Configuration / Reconfiguration)
-Setting, cancellation, and change processing of PSCell 54 and Scell 52 for SeNB 20-Instruction for transfer process of untransmitted data to switching destination cell for SeNB 20-Switching instruction for SeNB 20 to another SeNB. In addition, an instruction to transfer unsent data to the switching destination SeNB

  Here, S-RLF will be described. The cause of the occurrence of S-RLF can be classified into the following three cases, and can be detected by the SeNB 20 or the UE 30 in the following process in each case. Those skilled in the art will appreciate that these detections can be performed using known techniques.

(1) Cause due to a problem in PhysicalLayer-The SeNB 20 detects communication quality based on CQI and HARQ feedback information from the UE 30 as an index.
-In UE30, it detects based on the grade of the deterioration of the communication quality by radio link monitoring (RadioLinkMonitoring).

(2) Cause due to a problem in MAC (medium access control) Layer-Detection based on the number of retransmissions in Contention-based random access in UE30.
-In SeNB20 or UE30, the detection based on the frequency | count of retransmission in Contention-Free random access.

(3) Causes due to problems in RLC (radio link control) Layer ・ Detection when the maximum number of retransmissions of the downlink radio link by the SeNB 20 in the RLC AM entity is exceeded, or the maximum number of retransmissions of the uplink radio link by the UE 30 is exceeded Detection in case of exceeding the maximum number of retransmissions of uplink / downlink radio link by SeNB 20 in RLC UM entity, or detection in case of exceeding maximum number of retransmissions of uplink radio link by UE 30

  The information related to the communication quality degradation state received by the MeNB 10 from the SeNB 20 or the UE 30 may include information related to the cause of the communication quality degradation state and / or the generation cell. As the cause of occurrence of the communication quality degradation state, a cause identifier that identifies the three causes described above may be defined, and the cause identifier may be included in the information. In addition, for the cell in which the communication quality deteriorates, the cell ID related to the cell may be included in the information. Further, when both the cause of occurrence of the communication quality degradation state and the generated cell are included, for example, identification information indicating any one of ten types described later may be included.

  Here, when the information regarding a communication quality degradation state is received from both SeNB20 and UE30, MeNB control part 14 may implement the action according to any one information. In addition, the MeNB control unit 14 may preferentially determine information on either the UE 30 or the SeNB 20. In addition, the MeNB control unit 14 may select information to be prioritized in consideration of information related to a communication quality degradation state received in the past.

(Configuration example of SeNB 20)
FIG. 3 is a diagram illustrating a configuration example of the SeNB 20 of FIG. The SeNB 20 includes a SeNB transmission unit 22, a SeNB control unit 24, and a SeNB storage unit 26.

  The SeNB control unit 24 performs processing in any of the three cases described above to detect a cell related to a communication quality degradation state that has occurred on the radio link between the SeNB 20 and the UE 30, and the communication quality Estimate the cause of the degraded state. When the communication quality deterioration state is detected, the SeNB control unit 24 includes information on the cause of the occurrence of the communication quality deterioration state. Alternatively, instead of information related to the cause of the communication quality deterioration state, information for identifying the cell in which the communication quality deterioration state has occurred may be included. In addition to the information related to the cause of the communication quality deterioration state, Thus, information for specifying the cell in which the communication quality degradation state has occurred may be included.

  In addition, when the SeNB control unit 24 detects a communication quality deterioration or a communication quality deterioration state in any cell on the radio link between the SeNB 20 and the UE 30, the SeNB control unit 24 performs a use cell switching process.

  The SeNB storage unit 26 stores untransmitted data to be transmitted to the UE 30 for each cell. The SeNB storage unit 26 reads out untransmitted data corresponding to the cell according to the instruction in accordance with the instruction from the SeNB transmission unit 22.

  The SeNB transmission unit 22 notifies the MeNB 10 of information regarding the communication quality degradation state detected by the SeNB control unit 24. When the SeNB control unit 24 detects a communication quality deterioration state on the radio link in the primary cell PScell 54 of the SeNB 20, the SeNB transmission unit 22 notifies the primary cell PCell 42 of the MeNB 10 of the communication quality deterioration state.

  Moreover, in the SeNB control part 24, when the communication quality degradation state on the radio link in cells other than the primary cell PScell54 of SeNB20 is detected, SeNB transmission part 22 is communication quality degradation state with respect to primary cell PCell42 of MeNB10. Notify information about.

Here, the information regarding S-RLF notified to MeNB10 may be defined as follows.
・ S-RLF indication type 7: PHY layer problem on PScell54, if CQI and HARQ feedback based detection
・ S-RLF indication type 8: PHY layer problem on Scell52, if CQI and HARQ feedback based detection
・ S-RLF indication type 9: RLC layer DL problem on PScell54
・ S-RLF indication type 10: RLC layer DL problem on Scell52

  In addition, the SeNB storage unit 26 stores untransmitted data to be transmitted to the UE 30 for each cell. When the SeNB control unit 24 detects a deterioration in communication quality in any cell on the radio link between the SeNB 20 and the UE 30, the SeNB control unit 24 performs a process of switching used cells. The SeNB transmission unit 22 transfers untransmitted data stored in the SeNB storage unit 24 corresponding to the cell with deteriorated communication quality to the switching destination cell when the cell switching process is performed in the SeNB control unit 24. . In the case where all cells of the SeNB 20 are released and the SeNB 20 itself is switched, the switching destination cell may be the MeNB 10 or a cell in another SeNB. The other SeNB and the switching destination cell may be instructed by the MeNB.

  This will be specifically described. When the SeNB control unit 24 detects deterioration in communication quality in the secondary cell of the SeNB 20, the SeNB transmission unit 22 transfers untransmitted data to another secondary cell that is a switching destination in the SeNB 20. Moreover, SeNB transmission part 22 may transfer untransmitted data with respect to the primary cell which is the switching destination in SeNB20, when SeNB control part 24 detects the deterioration of the communication quality in the primary cell of SeNB20.

  In addition, when the SeNB control unit 24 detects deterioration of communication quality in all cells in use in the SeNB 20, the SeNB transmission unit 22 is configured to store all of the MeNB 10 primary cells stored in the SeNB storage unit 26. Unsent data may be transferred. Moreover, when transferring all untransmitted data stored in the SeNB storage unit 26 to the primary cell of the MeNB 10, the SeNB transmitting unit 22 transmits all the untransmitted data transferred via the primary cell of the MeNB 10, It may be transferred to the primary cell of another SeNB that should be newly targeted for Dual Connectivity communication. In addition, when transferring all untransmitted data stored in the SeNB storage unit 26 to the primary cell of the MeNB 10, the SeNB transmission unit 22 is the other SeNB primary of the SeNB that should be newly targeted for Dual Connectivity communication. All untransmitted data stored in the SeNB storage unit 26 may be directly transferred to the cell.

(Configuration example of UE 30)
FIG. 4 is a diagram illustrating a configuration example of the UE 30 in FIG. The UE 30 includes a UE transmission unit 32, a UE control unit 34, a UE storage unit 36, and a user IF 38.

  The UE control unit 34 performs processing in any of the three cases described above to detect a cell in a communication quality degradation state that has occurred on the radio link between the SeNB 20 and the UE 30, and the communication quality Estimate the cause of the degraded state. In addition, the UE control unit 34 may include information on the cause of the abnormal state in the information on the communication quality deterioration state. Alternatively, instead of information related to the cause of the communication quality deterioration state, information for identifying the cell in which the communication quality deterioration state has occurred may be included. In addition to the information related to the cause of the communication quality deterioration state, Thus, information for specifying the cell in which the communication quality degradation state has occurred may be included.

  The UE transmission unit 32 notifies the MeNB 10 or SeNB 20 of information related to the communication quality degradation state detected by the UE control unit 34. When the UE control unit 34 detects a communication quality deterioration state on the radio link in the PScell 54 that is the primary cell of the SeNB 20, the UE control unit 34 notifies the primary cell PCell 42 of the MeNB 10 of information related to the communication quality deterioration state.

  Further, when the UE control unit 34 detects a communication quality deterioration state on the radio link in a cell (Scell 52) other than the primary cell PScell 54 of the SeNB 20, the UE transmission unit 32 detects the primary cell PCell42 of the MeNB 10 or the primary cell PScell 54 of the SeNB 20 Is notified of information regarding the communication quality degradation state.

Here, the information regarding S-RLF notified to MeNB10 or SeNB20 may be defined as follows. Note that “RLM” is an abbreviation for Radio Link Monitoring, and “if RLM” includes a case where the quality of a radio link is monitored and an abnormal state is detected.
・ S-RLF indication type 1: PHY layer problem on PScell54, if RLM
・ S-RLF indication type 2: PHY layer problem on Scell52, if RLM
・ S-RLF indication type 3: MAC layer random access problem on PScell54
・ S-RLF indication type 4: MAC layer random access problem on Scell52
・ S-RLF indication type 5: RLC layer UL problem on PScell54
・ S-RLF indication type 6: RLC layer UL problem on Scell52

  The user IF 38 may include a screen interface, an input interface that receives input from a user such as a keyboard and a touch panel, and an image capturing unit such as a camera.

  The UE storage unit 36 may store data transmitted from the MeNB 10 or SeNB 20, and may store data obtained through the user IF 38 to be transmitted to the MeNB 10 or SeNB 20.

  Examples of the present invention will be specifically described below using Examples 1 to 10. In the first to fifth embodiments, it is assumed that one of the radio link cells between the UE 30 and the SeNB 20 is in the S-RLF state. Further, for convenience of explanation, the description will be made assuming that the communication quality degradation state is S-RLF. However, the present invention is not limited to this, and the present invention is also applied to a case where predetermined communication quality such as SINR or Eb / Ior is degraded. Needless to say, you can. Examples 6 to 10 are specific examples of data transfer processing after a communication quality deterioration state is detected.

  First, Example 1 will be described. Here, description will be made with reference to FIGS. In addition, about the structure and operation | movement already mentioned, the description is simplified by using the same code | symbol. The same applies hereinafter.

  FIG. 5 is a diagram illustrating a configuration example of the first wireless communication system 110 according to the first embodiment. FIG. 6 is a sequence diagram illustrating an operation example of FIG. In the first wireless communication system 110 illustrated in FIG. 5, the first embodiment detects an S-RLF generated in the PScell 54 that is a cell for communication with the UE 30 as indicated by “x” in the drawing. It is an example regarding the notification of the information regarding S-RLF. In the following, the sequence of the first embodiment will be described while associating (1) to (4) shown in FIG. 5 with S10 to S18 shown in FIG.

  (1) First, UE30 detects S-RLF of PScell54 by UE control part 34 (S10).

  (2) Next, UE30 notifies the information regarding S-RLF in which S-RLF indication type 1, type 3, or type 5 was shown with respect to PCell42 in MeNB10 (S12). The S-RLF indication type 1, type 3, or type 5 is selected according to the detection result of the S-RLF by the UE control unit 34.

  (3) Here, when MeNB10 receives the information regarding S-RLF notified from UE30, the action according to the content of the received information will be performed (S14). As an action to be executed, for example, a change process of PScell 54 may be performed, and further, an activation / deactivation process of Scell 52 may be performed (S16). Moreover, when the component carrier suitable for the change destination of PScell54 does not exist in SCG50, you may perform the process which changes SeNB20 into another SeNB20 (S16).

  (4) Finally, the MeNB 10 performs a reconfiguration process for changing the setting of the UE 30 in accordance with the executed action (S16).

  According to the above aspect, the UE 30 notifies the information about the S-RLF to the MeNB 10 that should be the center of the dual connectivity control, so that the recovery of the S-RLF can be executed promptly.

  Next, Example 2 will be described. Here, description will be made with reference to FIGS. FIG. 7 is a diagram of a configuration example of the second wireless communication system 120 according to the second embodiment. FIG. 8 is a sequence diagram illustrating an operation example of FIG.

  In the second wireless communication system 120 illustrated in FIG. 7, the second embodiment uses the S-RLF generated in the PScell 54, which is a cell for communication with the UE 30, as indicated by “x” in the drawing. It is an example regarding the notification of the information regarding S-RLF at the time of detecting. In the following, the sequence of the second embodiment will be described while associating (1) to (4) shown in FIG. 7 with S20 to S26 shown in FIG.

  (1) First, SeNB20 detects S-RLF of PScell54 by SeNB control part 24 (S20).

  (2) Next, SeNB20 notifies the information regarding S-RLF in which S-RLF indication type 7 or type 9 was shown with respect to PCell42 in MeNB10 (S22). The S-RLF indication type 7 or type 9 is selected according to the detection result of the S-RLF by the SeNB control unit 24.

  (3) Here, when MeNB10 receives the information regarding S-RLF notified from SeNB20, the action according to the content of the received information is performed (S24). As an action to be executed, for example, a change process of PScell 54 may be performed, and further an activation / deactivation process of Scell 52 may be performed (S26). Moreover, when the component carrier suitable for the change destination of PScell54 does not exist in SCG50, you may perform the process which changes SeNB20 to another SeNB (S26).

  (4) Finally, the MeNB 10 performs a reconfiguration process for changing the setting of the UE 30 in accordance with the executed action (S26).

  According to the above aspect, the SeNB 20 notifies the information about the S-RLF to the MeNB 10 that should be the center of Dual Connectivity control, so that the S-RLF can be quickly recovered.

  Next, Example 3 will be described. Here, it demonstrates using FIGS. 9-12. 9 and 10 are diagrams illustrating configuration examples of the 3-1 radio communication system 130 and the 3-2 radio communication system 132 according to the third embodiment, respectively. 11 and 12 are sequence diagrams showing examples of the operations of FIGS. 9 and 10, respectively.

  In the third embodiment, in the 3-1 radio communication system 130 and the 3-2 radio communication system 132 shown in FIGS. 9 and 10, as indicated by “x” in the drawings, the UE 30 is in Scell 52. It is an example regarding the notification of the information regarding S-RLF when the generated S-RLF is detected. The difference between FIG. 9 & FIG. 11 and FIG. 10 & FIG. 12 is that the notification destination of S-RLF is MeNB 10 or SeNB 20. In the following, the sequences of the third embodiment will be described, with (1) to (4) shown in FIGS. 9 and 10 respectively corresponding to S30 to S36 and S40 to S48 shown in FIGS. To do.

  (1) First, UE30 detects S-RLF of Scell52 by UE control part 34 (S30, S40).

(In the case of FIG. 9 & FIG. 11)
(2) Next, UE30 notifies the information regarding S-RLF in which S-RLF indication type 2, type 4, or type 6 was shown with respect to PCell42 in MeNB10 (S32). Alternatively, S-RLF indication type 2, type 4, or type 6 is selected according to the detection result of the S-RLF by the UE control unit 34.
(3) When the information about S-RLF is notified to the Pcell 42 of the MeNB 10 (FIGS. 9 and 11), the MeNB control unit 14 of the MeNB 10 requests the activation / deactivation procedure of the Scell 52 from the SeNB 20 (S34, S36). . (4) Finally, the MeNB 10 performs a reconfiguration process for changing the setting of the UE 30 in accordance with the executed action.

(In the case of FIG. 10 & FIG. 12)
(2) The UE 30 notifies the PS cell 54 in the SeNB 20 of information related to S-RLF in which S-RLF indication type 2, type 4, or type 6 is indicated (S42).
(3) On the other hand, when the information about S-RLF is notified to the PScell 54 of the SeNB 20 (FIGS. 10 and 12), the SeNB control unit 24 of the SeNB 20 performs the activates / deactivate process of the Scell 52 related to S-RLF (S44) The fact is reported to the MeNB 10 (S46). (4) Finally, the MeNB 10 performs a reconfiguration process for changing the setting of the UE 30 in accordance with the executed action (S48).

  According to the above aspect, the UE 30 notifies the information about the S-RLF to the MeNB 10 that should be the center of the dual connectivity control, so that the recovery of the S-RLF can be executed promptly.

  Further, the UE 30 directly notifies the SeNB 20 of the information about the S-RLF, so that the SeNB 20 itself can quickly execute the switching process of the Scell 52 related to the S-RLF, and thus the dual connectivity communication is quickly restored. It will be possible.

  UE30 may select either MeNB10 or SeNB20 as a notification destination of S-RLF. This selection may be alternatively determined depending on which cell of Pcell 42 and PScell 54 has a good communication state. This is because, according to such an aspect, a more preferable route is selected, so there is a possibility that the state of the S-RLF can be recovered more quickly. On the other hand, UE30 may transmit the information regarding S-RLF to both MeNB10 and SeNB20, without selecting. This is because the S-RLF state may be recovered more promptly by such an aspect.

  Next, Example 4 will be described. Here, it demonstrates using FIGS. 13-16. FIGS. 13 and 14 are diagrams illustrating configuration examples of the 4-1 wireless communication system 140 and the 4-2 wireless communication system 142 according to the fourth embodiment, respectively. FIGS. 15 and 16 are sequence diagrams showing examples of operations of FIGS. 13 and 14, respectively.

  In the fourth embodiment, in the 4-1 radio communication system 140 and the 4-2 radio communication system 142 shown in FIGS. 13 and 14, as indicated by “x” in the figure, the SeNB 20 is connected to the UE 30 and the Scell 52. It is an example regarding the notification of the information regarding S-RLF when S-RLF which generate | occur | produced in both is detected. The difference between FIG. 13 & FIG. 15 and FIG. 14 & FIG. 16 is that the SeNB 20 that detects the S-RLF first reports to the MeNB 10 and then performs the activation / deactivation procedure of the Scell 52 related to the S-RLF. The point is whether to do it autonomously. In the following, the sequences of the fourth embodiment will be described while associating (1) to (4) shown in FIGS. 13 and 14 with S50 to S56 and S60 to S66 shown in FIGS. To do.

  (1) First, SeNB20 detects S-RLF of Scell52 by SeNB control part 24 (S50, S60).

(In the case of FIG. 13 & FIG. 15)
(2) Next, SeNB20 notifies the information regarding S-RLF in which S-RLF indication type 8 or type 10 was shown with respect to PCell42 in MeNB10 (S52). The S-RLF indication type 8 or type 10 is selected according to the detection result of the S-RLF by the SeNB control unit 24.
(3) Here, when MeNB10 receives the information regarding S-RLF notified from SeNB20, the action according to the content of the received information is performed (S54). As an action to be executed, for example, activation / deactivation processing of Scell 52 may be performed (S56).
(4) Finally, the MeNB 10 performs a reconfiguration process for changing the setting of the UE 30 in accordance with the action executed in the SeNB 20 (S56).

(In the case of FIG. 14 & FIG. 16)
(2) The SeNB control unit 24 of the SeNB 20 performs activation / deactivation processing of the Scell 52 related to the S-RLF detected by itself (S62).
(3) Next, the SeNB 20 reports to the PCell 42 in the MeNB 10 that the activation / deactivation process of the Scell 52 has been completed (S64).
(4) Finally, the MeNB 10 performs a reconfiguration process for changing the setting of the UE 30 in accordance with the action executed in the SeNB 20 (S66).

  According to the above aspect, the SeNB 20 notifies the information about the S-RLF to the MeNB 10 that should be the center of Dual Connectivity control, so that the S-RLF can be quickly recovered. Moreover, S-RLF can be recovered more promptly by deferring reporting to the MeNB 10 and giving priority to handling of the Scell 52 in which S-RLF has occurred.

(Modification of Examples 1-4)
Next, Example 5 will be described. The fifth embodiment is a modification of the first to fourth embodiments. FIG. 17 is a diagram showing a fifth wireless communication system 150 according to a modified example of the present invention. This modification is an example related to notification of information related to the RLF when the UE 30 detects the RLF generated in the Scell 44, as indicated by “x” in the figure.

  In such a case, the UE 30 notifies the PCell 42 of information related to RLF. The notified MeNB 10 performs the activation / deactivation process on the Scell 44 related to the RLF, and performs the reconfiguration process for the UE 30.

  As another modification, the MeNB 10 itself may detect the RLF in the Scell 44. In this case, the activation / deactivation process can be quickly performed on the Scell 44 related to the RLF.

  As another modification, the MeNB 10 itself may detect the S-RLF in the PScell 54 and Scell 52 of the SeNB 20 as described in the first to fourth embodiments. For example, as a detection method, it is possible to refer to a Measurement Report regarding a neighboring base station notified from the UE 30 to the MeNB 10 and observe the time change thereof. Thereby, MeNB10 can start the recovery process of the cell concerning S-RLF promptly, without waiting for the notification of the information regarding S-RLF from SeNB20 or UE30.

  As another modification, the S-RLF recovery process in the MeNB 10 may be started when the information about the S-RLF for the same cell is received a certain number of times within a predetermined time. The predetermined time or a certain number of times may vary depending on the past S-RLF history, or may be designated from an upper layer. For example, it is assumed that not only S-RLF indication type 1 is received from UE 30, but also S-RLF indication type 7 that is the same S-RLF generation factor & notification to the same cell is received from SeNB20. The By such an aspect, the detection accuracy of S-RLF can be increased and unnecessary restoration processing due to erroneous detection of S-RLF can be reduced.

  Next, Example 6 will be described. Here, description will be made with reference to FIGS. 18 and 19. FIG. 18 is a diagram illustrating a configuration example of the sixth wireless communication system 160 according to the sixth embodiment. FIG. 19 is a sequence diagram illustrating an operation example of FIG.

  In Example 6, in the sixth wireless communication system 160 shown in FIG. 18, as indicated by “x” in the figure, communication quality degradation occurred in the Scell 52 that is a cell used for communication between the SeNB 20 and the UE 30. It is an example regarding the transfer process after a state is detected and the information regarding a communication quality degradation state is notified. The route for the transfer is indicated by a broken line arrow in the figure, and the same applies in Examples 7 to 10. In the following, the sequence of the sixth embodiment will be described while associating (1) to (4) shown in FIG. 18 with S70 to S78 shown in FIG.

  (1) First, the SeNB control unit 24 recognizes a communication quality degradation state that has occurred in the Scell 52 used in communication with the UE 30 (S70). The recognition of the communication quality degradation state in the Scell 52 may be made by notification from the UE 30 or by the SeNB control unit 24 detecting itself as shown in the third to fifth embodiments.

  (2) Next, the SeNB control unit 24 performs a deactivation process of the Scell 52 that is in a communication quality deterioration state and an activation process of the newScell 59 (S72). Further, the SeNB transmission unit 22 transfers untransmitted data that was scheduled to be transmitted to the UE 30 in the Scell 52 that has been in a communication quality degradation state to the newScell 59 (S72).

  (3) Thereafter, the SeNB transmission unit 22 notifies the MeNB 10 of the completion of the deactivation process of Scell 52 and the activation process of newScell 59 (S74).

  (4) Finally, the MeNB 10 performs a reconfiguration process for changing the setting of the UE 30 in accordance with the action executed in the SeNB 20 (S76), and after the process ends, the UE 30 Is notified to the MeNB 10 (S78).

  According to the above aspects, the data transfer process is more promptly performed for the MeNB 10 prior to the completion of the deactivation process of the Scell 52 that is in a communication quality deteriorated state and the activation process of the newScell 59. Unsent data can be protected.

  Next, Example 7 will be described. Here, description will be made with reference to FIGS. FIG. 20 is a diagram illustrating a configuration example of the seventh wireless communication system 170 according to the seventh embodiment. FIG. 21 is a sequence diagram illustrating an operation example of FIG.

  In the seventh embodiment, in the seventh wireless communication system 170 shown in FIG. 20, as shown by “x” in the figure, the communication quality degradation state that has occurred in the PScell 54 that is used for communication between the SeNB 20 and the UE 30 is shown. It is an example regarding the process after it is detected and the information regarding a communication quality degradation state is notified. In the following, the sequence of the seventh embodiment will be described while making (1) to (4) shown in FIG. 20 correspond to S80 to S90 shown in FIG.

  (1) First, the MeNB 10 recognizes a communication quality degradation state that has occurred in the PScell 54 used in communication with the UE 30 (S80). The recognition of the communication quality degradation state in the PScell 54 may be made by notifying from the UE 30 or notifying from the SeNB 20 as shown in the first and second embodiments.

  (2) Next, the MeNB transmission unit 12 instructs the SeNB 20 to change the PScell 54 (S82). The SeNB control unit 24 performs a change process of the PScell 54 in which the communication quality is deteriorated (S84). In the change process, a deactivation process of PScell 54 and an activation process of newPScell 58 may be performed. Further, the SeNB transmission unit 22 transfers untransmitted data that was scheduled to be transmitted to the UE 30 in the PS cell 54 in a communication quality degraded state to the new PS cell 58 (S84).

(3) Thereafter, the SeNB transmission unit 22 notifies the MeNB 10 of the completion of the change process of the PScell 54 (S86).
(4) Finally, the MeNB 10 performs a reconfiguration process for changing the setting of the UE 30 in accordance with the action executed in the SeNB 20 (S88), and after the process ends, the UE 30 indicates that the process is completed. Is notified to the MeNB 10 (S90).

  According to the above aspect, the unsent data can be protected more quickly by performing the data transfer process prior to the completion report of the change process of the PScell 54 in the communication quality degradation state to the MeNB 10. Can do.

  Next, Example 8 will be described. Here, a description will be given with reference to FIGS. FIG. 22 is a diagram of a configuration example of the eighth wireless communication system 180 according to the eighth embodiment. FIG. 23 is a sequence diagram illustrating an operation example of FIG.

  In the eighth wireless communication system 180 shown in FIG. 22, the eighth embodiment communicates in PScells 54 and Scells 52 that are all cells communicating with the UE 30 in the SeNB 20 as indicated by “x” in the figure. It is an example regarding the process after a quality degradation state is detected and the information regarding a communication quality degradation state is notified. In the following, the sequence of the eighth embodiment will be described while associating (1) to (4) shown in FIG. 22 with S100 to S108 shown in FIG.

  (1) First, the MeNB 10 recognizes a communication quality degradation state that has occurred in the PScell 54 and Scell 52 used in communication with the UE 30 (S100). The recognition of the communication quality degradation state in the PScell 54 and the Scell 52 may be made by being notified from the UE 30 or being notified from the SeNB 20 as shown in the first to fifth embodiments.

  (2) Next, the MeNB transmission unit 12 instructs the SeNB 20 to release the SeNB 20 and to transfer untransmitted data (S102). The SeNB control unit 24 performs a deactivation process and performs a release process on all of the PScells 54 and Scells 52 that are in a communication quality degraded state. Further, the SeNB transmission unit 22 transfers to the MeNB 10 all untransmitted data that was scheduled to be transmitted to the UE 30 in the PS cell 54 and the S cell 52 that are in a communication quality degraded state. As the transfer destination, unsent data corresponding to the PScell 54 may be sent to the PCell 42, and unsent data corresponding to the Scell 52 may be sent to the Scell 44.

(3) Thereafter, the SeNB transmission unit 22 sends a completion report to the MeNB 10 to the MeNB 10 (S104).
(4) Finally, the MeNB 10 performs a reconfiguration process for changing the setting of the UE 30 in accordance with the action executed in the SeNB 20 (S106), and after the process ends, the UE 30 Is notified to the MeNB 10 (S108).

  According to the above-described aspect, even when the communication quality deteriorates such that the SeNB 20 itself needs to be released, the data packet loss to the UE 30 is reduced by promptly transferring untransmitted data to the MeNB 10. Can be avoided.

  Next, Example 9 will be described. Here, the description will be made with reference to FIGS. 24 and 25. FIG. 24 is a diagram illustrating a configuration example of the ninth wireless communication system 190 according to the ninth embodiment. FIG. 25 is a sequence diagram illustrating an operation example of FIG. In the ninth wireless communication system 190, a Target SeNB 60 is illustrated as a transfer destination SeNB. Here, MeNB10, SeNB20, and TargetSeNB60 may mutually be connected by the backhaul line.

  In the ninth wireless communication system 190 illustrated in FIG. 24, the ninth embodiment performs communication in PScells 54 and Scells 52 that are all cells performing communication with the UE 30 in the SeNB 20 as indicated by “x” in the drawing. It is an example regarding the process after a quality degradation state is detected and the information regarding a communication quality degradation state is notified. In the following, the sequence of the ninth embodiment will be described while making (1) to (5) shown in FIG. 24 correspond to S110 to S124 shown in FIG.

  (1) First, the MeNB 10 recognizes a communication quality degradation state that has occurred in the PS cells 54 and S cells 52 used in communication with the UE 30 (S110). The recognition of the communication quality degradation state in the PScell 54 and the Scell 52 may be made by being notified from the UE 30 or being notified from the SeNB 20 as shown in the first to fifth embodiments.

  (2) Next, the MeNB transmitter 12 instructs the SeNB 20 to release the SeNB 20 and to transfer untransmitted data (S112). The SeNB control unit 24 performs a deactivation process and performs a release process on all of the PScells 54 and Scells 52 that are in a communication quality degraded state. Further, the SeNB transmission unit 22 transfers all untransmitted data that was scheduled to be transmitted to the UE 30 in the PS cell 54 and the S cell 52 that are in a communication quality degraded state, to the MENB 10.

  (3) Thereafter, the SeNB transmission unit 22 sends a completion report to the MeNB 10 to the MeNB 10 (S114).

  (4) Here, the MeNB 10 makes an addition request to the Target SeNB 60 to become an SeNB as one of the Dual Connectivity configurations (S116). In response to this request, the Target SeNB 60 sets PScell and Scell in the component carrier of its own SCG, and reports the result to the MeNB 10 (S118). Thereafter, the MeNB 10 transfers untransmitted data transferred from the SeNB 20 to the primary cell of the Target SeNB 60 (S120). As the transfer destination, untransmitted data corresponding to the PScell 54 may be set to the PSCell of the Target SeNB 60, and untransmitted data corresponding to the Scell 52 may be set to the Scell of the Target SeNB 60.

  (5) Finally, the MeNB 10 performs a reconfiguration process for changing the setting of the UE 30 in accordance with the action executed in the SeNB 20 (S122), and after the process ends, the UE 30 indicates that the process is completed. Is notified to the MeNB 10 (S124).

  According to the above-described aspect, even when the communication quality is deteriorated so that SeNB 20 itself needs to be released, untransmitted data is promptly transferred to Target SeNB 60 as a new connection destination via MeNB 10. By doing so, the loss of the data packet with respect to UE30 can be avoided.

  Next, Example 10 will be described. Here, a description will be given with reference to FIGS. FIG. 26 is a diagram illustrating a configuration example of the tenth wireless communication system 200 according to the tenth embodiment. FIG. 27 is a sequence diagram illustrating an operation example of FIG.

  In the tenth wireless communication system 200 shown in FIG. 26, the tenth embodiment communicates in PScells 54 and Scells 52 that are all cells communicating with the UE 30 in the SeNB 20 as indicated by “x” in the drawing. It is an example regarding the process after a quality degradation state is detected and the information regarding a communication quality degradation state is notified. In the following, the sequence of the tenth embodiment will be described while associating (1) to (5) shown in FIG. 26 with S130 to S144 shown in FIG.

  (1) First, the MeNB 10 recognizes the communication quality degradation state that has occurred in the PScell 54 and the Scell 52 used in communication with the UE 30 (S130). The recognition of the communication quality degradation state in the PScell 54 and the Scell 52 may be made by being notified from the UE 30 or being notified from the SeNB 20 as shown in the first to fifth embodiments.

  (2) Next, the MeNB 10 makes an addition request to the Target SeNB 60 to become a SeNB as one of the Dual Connectivity configurations (S132). In response to this request, the Target SeNB 60 sets PScell and Scell in the component carrier of its own SCG and reports the result to the MeNB 10 (S134).

  (3) Next, the MeNB transmission unit 12 instructs the SeNB 20 to release the SeNB 20 and to transfer the untransmitted data (S136).

  (4) Here, SeNB20 transfers all the unsent data which were scheduled to transmit to UE30 in PScell54 and Scell52 which became the communication quality degradation state with respect to the primary cell of TargetSeNB60 (S138). As the transfer destination, untransmitted data corresponding to the PScell 54 may be set to the PSCell of the Target SeNB 60, and untransmitted data corresponding to the Scell 52 may be set to the Scell of the Target SeNB 60. Next, the SeNB control unit 24 performs deactivation processing on all of the PScells 54 and Scells 52 in a communication quality degraded state, and performs release processing. Thereafter, the SeNB transmission unit 22 sends a completion report to the MeNB 10 to the MeNB 10 (S140).

  (5) Finally, the MeNB 10 performs a reconfiguration process for changing the setting of the UE 30 in accordance with the action executed in the SeNB 20 (S142), and after the process ends, the UE 30 indicates that the process has been completed. Is notified to the MeNB 10 (S144).

  According to the above aspect, even when the communication quality is deteriorated so that the SeNB 20 itself needs to be released, the untransmitted data is directly transferred to the Target SeNB 60 as a new connection destination without going through the MeNB 10. By doing so, the loss of the data packet with respect to UE30 can be avoided efficiently.

  In the above, this invention was demonstrated based on the Example. The present invention is not limited to the above-described embodiments and the contents of each embodiment, and various modifications can be made within the scope of the gist of the present invention. The above-mentioned embodiment is an exemplification, and various modifications can be made to the combination of each component and each processing process by combining each embodiment, and such a modification is also within the scope of the present invention. Will be understood by those skilled in the art.

It is a figure which shows the radio | wireless communications system concerning embodiment of this invention. It is a figure which shows the structural example of MeNB of FIG. It is a figure which shows the structural example of SeNB of FIG. It is a figure which shows the structural example of UE of FIG. 1 is a diagram illustrating a first wireless communication system according to a first embodiment. It is a sequence diagram which shows the operation example of FIG. It is a figure which shows the 2nd radio | wireless communications system concerning Example 2. FIG. It is a sequence diagram which shows the operation example of FIG. It is a figure which shows the 3rd-1 radio | wireless communications system concerning Example 3. FIG. It is a figure which shows the 3-2 radio | wireless communications system concerning Example 3. FIG. It is a sequence diagram which shows the operation example of FIG. It is a sequence diagram which shows the operation example of FIG. It is a figure which shows the 4-1 radio | wireless communications system concerning Example 4. FIG. It is a figure which shows the 4-2 radio | wireless communications system concerning Example 4. FIG. It is a sequence diagram which shows the operation example of FIG. It is a sequence diagram which shows the operation example of FIG. It is a figure which shows the 5th radio | wireless communications system concerning the modification of Examples 1-4 of this invention. FIG. 10 is a diagram illustrating a sixth wireless communication system according to a sixth embodiment. It is a sequence diagram which shows the operation example of FIG. FIG. 10 is a diagram illustrating a seventh wireless communication system according to a seventh embodiment. It is a sequence diagram which shows the operation example of FIG. FIG. 10 is a diagram illustrating an eighth wireless communication system according to an eighth embodiment. FIG. 23 is a sequence diagram illustrating an operation example of FIG. 22. FIG. 10 is a diagram illustrating a ninth wireless communication system according to a ninth embodiment. FIG. 25 is a sequence diagram illustrating an operation example of FIG. 24. It is a figure which shows the 10th radio | wireless communications system concerning Example 10. FIG. FIG. 27 is a sequence diagram illustrating an operation example of FIG. 26.

10 MeNB, 12 MeNB transmission unit, 14 MeNB control unit, 16 MeNB storage unit, 20 SeNB, 22 SeNB transmission unit, 24 SeNB control unit, 26 SeNB storage unit, 30 UE, 32 UE transmission unit, 34 UE control unit, 36 UE storage unit, 38 user IF, 40 MCG, 42 PCell, 44 Scell, 46 NotServingCell, 52 Scell, 54 PScell, 56 NotServingCell, 58 newPScell, 59 newScell, 100 Target SeNB, 100 Target communication system 120 2nd wireless communication system, 130 3rd-1 wireless communication system, 132 3-2 wireless communication system, 140th 4-1 wireless communication system, 142 4-2 wireless communication system, 150 fifth wireless communication system, 160 sixth wireless communication system, 170 seventh wireless communication system, 180 eighth wireless communication system, 190 ninth wireless communication system 200 Tenth wireless communication system.

Claims (5)

A communication device provided in the secondary base station in a wireless communication system including a master base station and a secondary base station that are in a master-slave relationship with each other, and a terminal device that executes Dual Connectivity communication between both base stations,
One of a plurality of component carriers is set as a primary cell or a secondary cell for communication of the master base station or the secondary base station,
In the primary cell, uplink and downlink communication is possible, and in the secondary cell, only downlink communication is possible,
The communication device
When communication quality deterioration information indicating that the communication quality of any secondary cell on the radio link between the secondary base station and the terminal device has deteriorated is acquired , the deactivation of the secondary cell having the deteriorated communication quality A control unit that performs activation processing of a new secondary cell to be processed and switched, and
A storage unit for storing untransmitted data to be transmitted to the terminal device using any of the secondary cells on the radio link between the secondary base station and the terminal device ;
If the activation process of the new secondary cell in the control section is performed, the unsent data stored in the storage unit, reads out the unsent data corresponding to a secondary cell in which the communication quality is deteriorated, the A transmitter for transferring to a new secondary cell;
Equipped with a,
The transmission unit transmits information for notifying completion of deactivation processing of a secondary cell whose communication quality has deteriorated and completion of activation processing of a new secondary cell as a switching destination after transfer of the untransmitted data. that sends to the base station communication device. The communication device according to claim 1, wherein the control unit acquires the communication quality deterioration information by receiving the communication quality deterioration information from the terminal device. The said control part acquires the said communication quality degradation information by detecting the degradation of the communication quality of any secondary cell on the radio link between the said secondary base station and the said terminal device. Communication device. A communication method performed by the secondary base station in a wireless communication system including a master base station and a secondary base station that are in a master-slave relationship with each other, and a terminal device that executes Dual Connectivity communication between both base stations,
One of a plurality of component carriers is set as a primary cell or a secondary cell for communication of the master base station or the secondary base station,
In the primary cell, uplink and downlink communication is possible, and in the secondary cell, only downlink communication is possible,
The communication method is:
When communication quality deterioration information indicating that the communication quality of any secondary cell cell on the radio link between the secondary base station and the terminal device has deteriorated is acquired , the deactivation of the secondary cell having the deteriorated communication quality Performing the activation process of the new secondary cell that is the process and the switching destination; and
And forwarding when activation processing of the new secondary cell has been performed, the unsent data in a secondary cell in which the communication quality is deteriorated by the new secondary cells,
Transmitting the information for notifying the completion of the deactivation process of the secondary cell whose communication quality has deteriorated and the completion of the activation process of the new secondary cell to be switched to the master base station;
Including a communication method. For causing a computer provided in the secondary base station in a wireless communication system to include a master base station and a secondary base station that are in a master-slave relationship with each other, and a terminal device that executes Dual Connectivity communication between both base stations . A program,
One of a plurality of component carriers is set as a primary cell or a secondary cell for communication of the master base station or the secondary base station,
In the primary cell, uplink and downlink communication is possible, and in the secondary cell, only downlink communication is possible,
The program is
When communication quality deterioration information indicating that the communication quality of any secondary cell on the radio link between the secondary base station and the terminal device has deteriorated is acquired , the deactivation of the secondary cell having the deteriorated communication quality Performing the activation process of the new secondary cell that is the process and the switching destination; and
And forwarding when activation processing of the new secondary cell has been performed, the unsent data in a secondary cell in which the communication quality is deteriorated by the new secondary cells,
Transmitting the information for notifying the completion of the deactivation process of the secondary cell whose communication quality has deteriorated and the completion of the activation process of the new secondary cell to be switched to the master base station;
A program that causes a computer to execute.

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