[0001]The present disclosure relates to wireless communication networks, in particular to Dual Connectivity (DC).
Background technique
[0002]
　3GPP Release 12 defines a Dual Connectivity (DC) (e.g., see Non-Patent Documents 1 and 2). DC is similar to Coordinated Multipoint introduced in 3GPP Release 11 (CoMP) different. In particular, in DC, the different carrier frequencies out with macrocells and small cells (picocells) is used, the wireless terminal (User Equipment (UE)) to perform a two Medium Access Control (MAC) entity (i.e., UE utilizes radio resources provided by two independent scheduler of the master base station (master eNodeB (MeNB)) and the secondary base station (secondary eNB (SeNB))), and the UE simultaneous use of at least two UL carrier there is a need to support.
[0003]
　In DC of 3GPP Release 12, UE is connected to one MeNB and one SeNB. UE that is set to DC (DC UE) uses at least two Radio Link Control (RLC) entity and two MAC entities for data flow in each of the MeNB and SeNB. MeNB at DC is the eNB that terminates S1-MME for DC UE. SeNB in ​​DC provide additional radio resources to the DC UE. 1 or more serving cells is provided to the UE by the MeNB is called Master Cell Group (MCG), one or more serving cells is provided to the UE by the SeNB called Secondary Cell Group (SCG). MCG is 1 or more serving cell associated with the MeNB, including Primary Cell (PCell) optional one or more Secondary Cells (SCells). SCG is 1 or more serving cells associated with SeNB, including Primary Secondary Cell (PSCell) optional one or more Secondary Cells (SCells). In DC of 3GPP Release 12 is PSCell is a special cell in the SCG, different from the conventional SCell in that the uplink for UE (PUCCH) is set.
[0004]
　The control plane architecture for DC, the S1-MME only one exists for each one DC UE. The S1-MME is set between the MeNB and Mobility Management Entity (MME), MeNB terminates the S1-MME. Signaling between the MeNB and SeNB about DC UE is performed using the signaling interface between eNB (ie, X2-C).
[0005]
　Two user plane architecture for DC is allowed. In one architecture, S1-U is terminated only at MeNB, the user plane data are transferred using the X2-U to SeNB from MeNB. In another architecture, it is possible to S1-U is terminated even SeNB.
[0006]
　Thus, three kinds of radio bearers for DC, i.e. MCG bearer split bearer, and SCG bearer is defined. For the MCG bearer, MeNB is terminated S1-U connection with the Serving Gateway (S-GW), the wireless protocol is arranged only MeNB to use MeNB resources. Therefore, SeNB is not involved in the transfer of user plane data in the Uu interface regarding MCG bearer.
[0007]
　With respect to the split bearer, MeNB is terminated S1-U connection to the S-GW, Packet Data Convergence Protocol (PDCP) data (PDCP Protocol Data Unit (PDCP PDU)) is transferred between the MeNB and SeNB. Thus, both the MeNB and SeNB the transfer of user plane data in the Uu interface regarding split bearers are involved.
[0008]
　For the SeNB bearer, SeNB is terminated S1-U connection to the S-GW, the wireless protocol is arranged only SeNB to use the SeNB resources. Therefore, MeNB is not involved in the transfer of user plane data in the Uu interface related SCG bearer.
[0009]
　Some whole procedure for DC is defined in Non-Patent Document 1 (e.g., see Non-Patent Document 1 section 10.1.2.8).
[0010]
SeNB Addition, steps (procedure):
　The procedure is initiated by the MeNB to establish a UE context in the SeNB. The procedure is used to add the first cell in the least SCG (ie, PSCell). In this case, at least one bearer (split bearer or SCG bearer) is set always in the SCG.
[0011]
SeNB Modification Procedure:
　The procedure is used to make changes in SCG in the SeNB, initiated by MeNB or SeNB. The procedure is used in the same SeNB, for then-or releasing establish and modify the bearer context, to send a bearer context to SeNB (or from SeNB), or to modify other properties of the UE context It is. MeNB is, SCG SCells, using the SCG bearer (s), and split the procedures to add or release the SCG portion bearer (s). MeNB further using the procedure in order to trigger PSCell changes with PSCell release.
[0012]
SeNB Release Procedure:
　The procedure is initiated by the MeNB or SeNB, is used to initiate the release of the UE context in SeNB.
[0013]
Intra-MeNB Change Procedure:
　The procedure is used in order to perform a handover in the same MeNB while maintaining the SCG in the same SeNB (keep).
[0014]
SeNB Change Procedure:
　The procedure is used to change the SCG between SeNB (Inter-SeNB) (Change ). The procedure is initiated by MeNB, transfers UE context from the source SeNB the target SeNB, is used to change from the SeNB that the SCG settings in UE (SCG configuration) to another SeNB. The procedure is basically realized by the combination of the SeNB Addition, procedures and SeNB Release procedure.
[0015]
MeNB-to eNB Change Procedure:
　The procedure is initiated by the MeNB. The procedure is used to transfer context data from the source MeNB and source SeNB to the target eNB.
[0016]
　Transfer of signaling and user plane data between the MeNB and SeNB in DC is performed in the X2 interface. Accordingly, X2 procedure for DC below are defined (e.g., see Section 8.6 and Section 9.1.3 of Non-Patent Document 2). Some of the whole procedure described above utilizes an X2 procedures for these DC.
· SeNB Addition Preparation procedure
· MeNB initiated SeNB Modification Preparation procedure
· SeNB initiated SeNB Modification procedure
· MeNB initiated SeNB Release procedure
· SeNB initiated SeNB Release procedure
[0017]
　In 3GPP Release 12, if the UE handover from the MeNB to another eNB (Target eNB), MeNB to eNB Change procedure described above is used. In this procedure, SeNB (SCG) is completely released (release). Therefore, if it is required SCG after the handover, a target eNB needs to perform again SeNB Addition, steps after completion of the handover. That is, the MeNB-to eNB Change procedure, in addition to the normal handover procedure, the same signaling and SeNB Change procedure, i.e. requiring a combination of SeNB Release procedure SeNB Addition, procedures. Further, with respect to SCG bearer, data forwarding to the source MeNB is made from SeNB, it is necessary to further data forwarding from the source MeNB to the target eNB is performed.
[0018]
　In 3GPP Release 13, it is considered to support the MeNB handover involving inter MeNB (Inter-MeNB) handover, or the SeNB Addition, steps from sources MeNB without SeNB change (change) the target MeNB. By these procedures are supported, may SeNB Addition, procedures for the target eNB sets anew SCG to SeNB becomes unnecessary. Further, the data forwarding related SCG bearer to the source MeNB, and data forwarding related to the SCG bearer from the source MeNB to the target eNB may become unnecessary from SeNB.
[0019]
　Incidentally, Patent Document 1 also wireless terminal discloses several procedures for handover to the second master base station from the first master base station during Dual Connectivity. In one procedure disclosed in Patent Document 1, when the wireless terminal performs a handover from the first master base station to the second master base station during Dual Connectivity, first master base station to the secondary base station requests to suspend service provision in SCell, secondary base station holds the communication status information in SCell with service interruption provided in SCell. Furthermore, in this procedure, the second master base station transmits an indication of communication restart the secondary base station after the handover, the communication condition at the SCell a secondary base station in response to the reception of the instruction is held in the secondary base station restart the service in the SCell based on the information. Communication status information in the SCell, for example, (a) transmission status or receiving status of the user data (User Plane (U-plane)), (b) the service information, (c) bearer information, and (d) radio resource configuration information comprising at least one of.
CITATION
Patent Literature
[0020]
Patent Document 1: International Publication No. WO 2014/103145
Non-Patent Document
[0021]
非特許文献1 : 3GPP TS 36.300 V12.6.0 (2015-06), “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description; Stage 2 (Release 12)”, June 2015
非特許文献2 : 3GPP TS 36.423 V12.6.0 (2015-06), “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access Network (E-UTRAN); X2 application protocol (X2AP) (Release 12)”, June 2015
Summary of the Invention
Problems that the Invention is to Solve
[0022]
　MeNB change from first MeNB without SeNB changes to a second MeNB (or MeNB handover), or MeNB changes with SeNB Addition, (or MeNB handover), the existing related DC specified in 3GPP Release 12 it is realized by using X2 procedures and X2 messages is preferred. However, in these MeNB changes, SeNB must behave differently than SeNB Addition, procedures and SeNB Release procedure of 3GPP Release 12.
[0023]
　One objective to be achieved is the embodiment disclosed herein, the secondary base station while providing a Dual Connectivity to the wireless terminal (UE) (SeNB) master base station without the release of ( MeNB) change procedure or a master base station with the additional secondary base station (SeNB) a (MeNB) change procedure, using the existing inter-base station interface (X2 in interface) procedures and inter-base station signaling message (X2 message) It contributes to making the apparatus is to provide a method, and a program. Incidentally, this objective should embodiment disclosed herein is noted that only one of a plurality of objects to be achieved. Other objects or problems and novel features will become apparent from the description, or the accompanying drawings of this specification.
Means for Solving the Problems
[0024]
　In a first aspect, the base station device includes at least one processor coupled to at least one wireless transceiver, and the at least one wireless transceiver. Wherein the at least one processor, SeNB addition request message from the second master base station while providing secondary cell group for dual connectivity in conjunction with the first master base station (SCG) to the wireless terminal when receiving the explicit or implied that the SeNB addition request message is changed to the second master base station wherein dual connectivity of the master base station from the first master base station for the wireless terminal in response to include a first information element indicating a manner, the SeNB addition request message is configured to recognize the requesting modification of settings related to the SCG.
[0025]
　In a second aspect, the method of the secondary base station,
a while (a) providing a secondary cell group for dual connectivity in conjunction with the first master base station (SCG) to the wireless terminal 2 from the master base station receiving the SeNB addition request message, and
(b) the SeNB addition request message is said dual connectivity master base station and the second from the first master base station for the wireless terminal in response to include an explicit or implicitly first information element indicating that the change to the master base station, to recognize said SeNB addition request message is requesting modification of settings related to the SCG,
including.
[0026]
　In a third aspect, the program includes the when loaded into a computer, instructions for performing the method according to the second aspect described above to a computer (software code).
[0027]
　In a fourth aspect, the wireless terminal includes the first master base station, the second master base station, and at least one radio transceiver for communicating with the secondary base station, and at least one processor. The secondary base station, wherein the second master while the secondary base station is providing the secondary cell group (SCG) for dual connectivity in conjunction with the first master base station to said wireless terminal when receiving the SeNB addition request message from the base station is changed to the SeNB addition request message is the second master base station wherein dual connectivity of the master base station from the first master base station for the wireless terminal in response to include an explicit or implicitly indicate the first information element Rukoto, the SeNB addition request message is configured to recognize the requesting modification of settings related to the SCG. Wherein the at least one processor communicates with the first master base station and the second master base station, while maintaining the connection to the SCG of the secondary base station, said master base station of the dual connectivity It is configured to change to the second master base station from the first master base station.
Effect of the invention
[0028]
　According to the embodiments described above, additional a Dual Connectivity wireless terminal master base station without releasing the secondary base station (SeNB) while offering the (UE) (MeNB) change procedure or secondary base station (SeNB) the master base station (MeNB) change procedure involving contributes to be performed using the existing inter-base station interface (X2 in interface) procedures and inter-base station signaling message (X2 message) apparatus, a method, and a program It can be provided.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029]
It is a diagram illustrating a configuration example of a wireless communication network according to FIG. 1 with some embodiments.
Is a sequence diagram showing an example of the overall procedure of MeNB changes according to FIG. 2A] Some embodiments (MeNB handover).
It is a sequence diagram showing an example of the overall procedure of MeNB changes according to FIG. 2B] Some embodiments (MeNB handover).
3 is a sequence diagram for explaining the operation of the SeNB according to the first embodiment.
4 is a flowchart showing an example of the operation of the SeNB according to the first embodiment.
5 is a sequence diagram for explaining the operation of the SeNB according to a second embodiment.
6 is a flowchart showing an example of the operation of the SeNB according to a second embodiment.
7 is a sequence diagram for explaining the operation of the SeNB according to a third embodiment.
Is a block diagram showing an exemplary configuration of a base station according to FIG. 8 some embodiments.
It is a block diagram showing a configuration example of a radio terminal according to FIG. 9 some embodiments.
DESCRIPTION OF THE INVENTION
[0030]
　Hereinafter, specific embodiments will be described in detail with reference to the drawings. In the drawings, the same or corresponding components are denoted by the same reference numerals, for clarity of description, repeated explanation is omitted as appropriate.
[0031]
　The following several embodiments shown in will be described an Evolved Packet System (EPS) that houses the LTE and SAE (System Architecture Evolution) as a main target. However, these embodiments are not intended to be limited to EPS, other mobile communication networks or systems, for example 3GPP UMTS, 3GPP2 CDMA2000 systems (1xRTT, HRPD (High Rate Packet Data)), global system for mobile communications ( GSM (TM)) / General packet radio service (GPRS) system, and may be applied to WiMAX systems.
[0032]
　Figure 1 shows a configuration example of a wireless communication network according to some embodiments. In the example of FIG. 1, a wireless communication network includes a base station (eNB) 1, base station (eNB) 2, a base station (eNB) 3, and the wireless terminal (UE) 4. eNB1 and eNB2 operate respectively as MeNB and SeNB for Dual Connectivity (DC) to UE4. UE4 is set to DC by MeNB1, simultaneously utilizing the SCG comprising a cell 21 provided by the MCG and SeNB2 including the cell 11 provided by MeNB1.
[0033]
　In some embodiments, as shown in FIG. 1, while the SeNB2 is providing SCG for DC in conjunction with eNB (MeNB) 1 to UE4, the MeNB of DC for UE4 eNB1 handling MeNB changes 101 to change eNB3 from. After MeNB changes, UE4 is set to DC by MeNB3, simultaneously utilizing the SCG comprising a cell 21 provided by the MCG and SeNB2 including the cell 31 provided by MeNB3. Such MeNB changes may also be referred to as MeNB handover. The referred to eNB1 is MeNB before MeNB change (MeNB handover) source MeNB (S-MeNB), the eNB3 a MeNB after MeNB changed (MeNB handover) is called a target MeNB (T-MeNB) below .
[0034]
　Each eNBs1 ~ 3 shown in FIG. 1 may be a Centralized Radio Access Network (C-RAN) Baseband Unit used in the architecture (BBU). In other words, each eNB shown in FIG. 1 may be a RAN node connected to one or more Remote Radio Head (RRH). In some implementations, each of eNBs1 ~ 3 as BBU is responsible for digital baseband signal processing control plane processing and user plane. Meanwhile, RRH is responsible for analog Radio Frequency (RF) signal processing (eg, frequency conversion and signal amplification). Incidentally, C-RAN may also be referred to as the Cloud RAN. Further, BBU may also be referred to as a Radio Equipment Controller (REC) or Data Unit (DU). The RRH, Radio Equipment (RE), Radio Unit (RU), or sometimes referred to as Remote Radio Unit (RRU).
[0035]
　2A and 2B, an example of the overall procedure of MeNB change according to some embodiments (MeNB handover) shows a (Step 200). Incidentally, as described later, MeNB handover procedure 200 encompasses a procedure corresponding to the SeNB Addition, the procedure of 3GPP Release 12 (steps 202 and 203). In other words, the procedure 200 is MeNB changed (MeNB handover) procedure with additional SeNB while offering Dual Connectivity to UE4. In other words, the procedure 200 is MeNB changed (MeNB handover) procedure without the release of SeNB2 while offering Dual Connectivity to UE4.
[0036]
　In step 201, S-MeNB1 requests MeNB handover of UE4 to T-MeNB3. Handover request message of step 201 may also be referred to as MeNB change request message.
[0037]
　In step 202, in response to receiving a handover request message in step 201, T-MeNB3 transmits SeNB add request (SeNB Addition, Request) message to SeNB2. SeNB additional request (SeNB Addition Request) message may be referred to as SCG additional request (SCG Addition Request) message. The SeNB Addition, Request message indicates the character of the radio access bearer (ie, E-UTRAN Radio Access Bearer (E-RAB)) (characteristics), for requesting allocation of the radio resources for a particular E-RAB to SeNB2 . Characteristics of E-RAB, for example, E-RAB identifier (E-RAB ID), and shows a bearer type (ie, SCG bearer or split bearer). Here, the bearer type is also referred to as a DRB type. The SeNB Addition, Request message further, information for SCG settings including MCG setting (MCG Configuration) and UE capability (UE capabilities) (SCG-ConfigInfo) may contain.
[0038]
　SeNB2, in response to receipt of SeNB Addition, Request message from the T-MeNB3, radio resources and control plane (C-plane) resources was prepared, to prepare the transport network resources for SCG bearer. Then, SeNB2 transmits SCG configure (SCG-Config) encompassing response message (SeNB Addition Request Acknowledge) to the T-MeNB3 (step 203). SCG-Config, for example including PSCellToAddMod IE, may include RadioResourceConfigDedicatedSCG IE.
[0039]
　At step 204, T-MeNB3 transmits a response message indicating acceptance of the handover request (Handover Request Acknowledge) to the S-MeNB1. In step 205, in response to receiving the Handover Request Acknowledge message, S-MeNB1 transmits SeNB release request (SeNB Release Request) message to SeNB2. SeNB release request (SeNB Release Request) message may be referred to as SCG release request (SCG Release Request) message.
[0040]
　In step 206, S-MeNB1 requests PCell in MCG (eg, cell 11) radio resource control in the (Radio Resource Control (RRC)) reconfiguration of the connection (reconfiguration) to UE4. RRC Connection Reconfiguration message in step 206, the mobility control information on T-MeNB3 (Mobility Control Info) and MCG settings, and configuration information about SCG of SeNB2 (SCG Configuration, ie, scg-ConfigPartMCG (eg, scg-Counter), scg including the -ConfigPartSCG). Thus, UE4 is connected to SCG of SeNB2 (i.e., at least one bearer (SCG bearer or split bearer)) while maintaining the, the master base station of the DC switch from S-MeNB1 to T-MeNB3 Inter-eNB It recognizes that has been instructed to execute the Handover. For example, UE4, upon receiving the RRC Connection Reconfiguration message, resets the MCG side MAC entity MAC of (MCG MAC) and SCG side entity (SCG MAC). Then, re-establishment of the MCG side PDCP entity and (MCG PDCP) (for SCG bearer only) SCG side PDCP entity (SCG PDCP) (re-establish) to. Subsequently, re-establish the MCG side of RLC entity (MCG RLC) and SCG side of RLC entity (SCG RLC) (re-establish) to.
[0041]
　In step 207 and 208, UE4, in order to synchronize the T-MeNB3, perform the random access procedure, notifying the completion of the RRC reconfiguration, including modification of the handover confirmation (confirm) and MCG setting and SCG set (or changed) the RRC Connection Reconfiguration Complete message to be transmitted to the T-MeNB3.
[0042]
　In step 209, UE4 according RRC Connection Reconfiguration message new SCG settings received in step 206 (including the Mobility Control InfoSCG), executes the random access procedure to synchronize with SeNB2.
[0043]
　In step 210, T-MeNB3 informs in response to the reception of RRC Connection Reconfiguration message (step 208) from UE4, the completion of the SeNB reconstituted SeNB2 (SeNB Reconfiguration Complete message).
[0044]
　In step 211, S-MeNB1 is reported data communication context for MCG, i.e. transmits the SN Status Transfer message to the T-MeNB3. The SN Status Transfer message, for example, the uplink PDCP sequence number for MCG bearer (Sequence Number (SN)), uplink hyper frame number (Hyper Frame Number (HFN)), downlink PDCP sequence number and downlink including the hyper frame number. The SN Status Transfer message may include the PDCP sequence number and a hyperframe number for the split bearer. In step 212, S-MeNB1 starts forwarding to the T-MeNB3 downlink user data unsent received from S-GW 5.
[0045]
　In step 213, T-MeNB3 starts S1 path switch procedure. The S1 path switch procedure of steps 213-217, with one or more S1 bearer between the S-GW 5 and T-MeNB3 for MCG bearer (and split bearer optional) (215), S for SCG bearer S1 bearer (216) is set between the -GW5 and SeNB2. Incidentally, if there is no correction of the SCG bearer (E-RAB), S1 set bearer (216) between the S-GW 5 and SeNB2 may be the same as before the start of the handover between the MeNB. For example, S1 path switch procedure may be omitted.
[0046]
　In step 218, T-MeNB3 is a UE Context Release message sent to S-MeNB1, starts UE Context Release procedure. In response to receiving the UE Context Release message (step 218) from the T-MeNB3, S-MeNB1 can release radio and C-plane resources associated with the UE context. In step 219, S-MeNB1 in response to the reception of the UE Context Release message from the T-MeNB3, sends a UE Context Release message to SeNB2.
[0047]
　In the following, some embodiments are described. These embodiments may be implemented independently, or may be implemented in appropriate combination. These embodiments are provided for purposes of illustration (illustration).
[0048]

　MeNB change procedure shown in FIGS. 2A and 2B, using existing SeNB Addition, procedures and SeNB Release procedure, involving release of MeNB change procedure (or SeNB2 with additional SeNB is realized without MeNB change procedure). Therefore, in the procedure shown in FIGS. 2A and 2B, SeNB2 must distinguish SeNB Addition, Request message from the T-MeNB3 a (step 202) and the existing (conventional) SeNB Addition, Request message. This is because, the SeNB Addition, Request message (step 202) is used to MeNB and MCG associated with SCG already set in SeNB2 (or E-RAB) in order to change the S-MeNB1 the T-MeNB3 and therefore in order to have different roles and the existing (conventional) SeNB Addition, Request message.
[0049]
　In the present embodiment, specific examples of the operations and messages structure of S-MeNB1, SeNB2, and T-MeNB3 for distinguishing SeNB Addition, Request message (step 202) shown in Figure 2A with the existing (conventional) Message There will be explained.
[0050]
　Figure 3 is a SeNB2 is MeNB (S-MeNB) 1 SeNB2 is SeNB Addition, Request message to another eNB while in cooperation providing the SCG for a DC to specific UE4 and (T-MeNB) 3 an example of the reception procedures shows (Step 300). Step 301 and 302 shown in FIG. 3 corresponds to steps 201 and 202 shown in Figure 2A. That is, in step 301, S-MeNB1 sends a handover request message for requesting the MeNB handover of UE4 to T-MeNB3. The handover request message may include, for example, before the handover MCG setting and SCG settings.
[0051]
　The handover request message (step 301), further, SeNB (or SCG, or bearer (SCG bearer or split bearer) of SCG) explicit from S-MeNB1 the T-MeNB3 that the MeNB changes while maintaining the or one or more additional information elements for implicitly convey. Thus, T-MeNB3 is the handover request in response to receiving from the S-MeNB1, SeNB (or SCG, or bearer (SCG bearer or split bearer) of SCG) changes MeNB still maintaining the (MeNB during handover) it can recognize that it is requesting.
[0052]
　In some implementations, as shown in FIG. 3, the additional information element included in a handover request message (step 301) (information element (s)), the implicit changes MeNB of DC for UE4 to indicate to, S-MeNB1 base station between the interfaces between the SeNB2 (ie, X2 interface) assigned by SeNB2 to uniquely identify the UE4 in the wireless terminal identifier (ie, SeNB UE X2AP ID) also include good. The additional information element is one or more bearer identifiers (eg, network bearer identity (E-RAB ID or eps-Bearer Identity for UE4 already set in SeNB2 for DC in conjunction with S-MeNB1 ), the identifier (DRB Identity data radio bearer (data radio bearer (DRB))), or may further include the same bearer identifier and these combinations).
[0053]
　Additionally or alternatively, in some implementations, additional information elements included in the handover request message (step 301) (information element (s)) is implicitly change the MeNB of DC for UE4 to illustrate, the terminal identifier assigned to UE4 by SeNB2 to uniquely identify the UE4 in SCG (eg, Cell- Radio Network Temporary identifier (C-RNTI)) may include. In this case, the additional information element is one or more bearer identifiers (eg, E-RAB ID or eps-Bearer Identity for UE4 already set in SeNB2 for DC in conjunction with S-MeNB1, DRB Identity, or may further include the same bearer identifier and these combinations). Furthermore, E-RAB ID is transmitted as an information element of the X2 message, eps-Bearer Identity and DRB Identity is included as an information element of the RRC layer in the container included in the X2 message (MeNB to SeNB Container) transmission it may be.
[0054]
　Additionally or alternatively, in some implementations, the handover request message additional information element included in the (step 301) (information element (s)) is, MeNB of DC for UE4 is MeNB (S-MeNB ) it may be explicitly indicated to be changed from 1 to MeNB (T-MeNB) 3. In this case, the additional information element, the bearer identifier (eg, E-RAB ID or eps-Bearer Identity for UE4 already set in SeNB2 for DC in conjunction with MeNB1, DRB Identity, or their it may indicate that the combination) is not changed.
[0055]
　In step 302, in response to receiving a handover request message in step 301, T-MeNB3 transmits the SeNB Addition, Request message to SeNB2. The SeNB Addition, Request message indicates the character of the radio access bearer (ie, E-UTRAN Radio Access Bearer (E-RAB)) (characteristics), for requesting allocation of the radio resources for a particular E-RAB to SeNB2 . Characteristics of E-RAB, for example, E-RAB identifier (E-RAB ID), and shows a bearer type (ie, SCG bearer or split bearer). Here, the bearer type is also referred to as a DRB type. The SeNB Addition, Request message further, information for SCG settings including MCG setting (MCG Configuration) and UE capability (UE capabilities) (SCG-ConfigInfo) may contain. Moreover, T-MeNB3, in SCG-ConfigInfo, to that using network bearer identifier (eg, eps-Bearer Identity) and data radio bearer identifier (DRB Identity) in DC between the S-MeNB1 and SeNB2 it may be specified to be set to the same value. Similarly, T-MeNB3 logical identifier (sCellIndex, ServCellIndex) cell 21 may be specified to be set to the same value as the one used in DC between the S-MeNB1 and SeNB2.
[0056]
　The SeNB Addition, Request message (step 302), further, SeNB (or SCG, or SCG bearer (SCG bearer or split bearer)) while maintaining the MeNB is to be changed to T-MeNB3 from S-MeNB1 SeNB2 to contain one or more additional information elements to convey explicitly or implicitly. The one or more additional information elements Information elements may be the same as the additional information element corresponding contained in the handover request message (step 301), may be directed from now.
[0057]
　That is, in some implementations, as shown in FIG. 3, the additional information element included in the SeNB Addition, Request message (step 302) (information element (s)), the changes of the MeNB of DC for UE4 in order to indicate implicitly, S-MeNB1 base station between the interfaces between the SeNB2 (ie, X2 interface) assigned by SeNB2 to uniquely identify the UE4 in the wireless terminal identifier (ie, SeNB UE X2AP ID) it may include a. In this case, the additional information element is one or more bearer identifiers (eg, E-RAB ID or eps-Bearer Identity for UE4 already set in SeNB2 for DC in conjunction with S-MeNB1, DRB Identity, or may further include the same bearer identifier and these combinations).
[0058]
　Additionally or alternatively, in some implementations, SeNB Addition, Request message additional information element included in the (step 302) (information element (s)), the implicit changes MeNB of DC for UE4 in order to indicate the terminal identifier (eg, C-RNTI) assigned to UE4 by SeNB2 to uniquely identify the UE4 in SCG it may contain. In this case, the additional information element is one or more bearer identifiers (eg, E-RAB ID or eps-Bearer Identity for UE4 already set in SeNB2 for DC in conjunction with S-MeNB1, DRB Identity, or may further include the same bearer identifier and these combinations).
[0059]
　Additionally or alternatively, in some implementations, additional information elements included in the SeNB Addition, Request message (step 302) (information element (s)) is, MeNB of DC for UE4 is MeNB (S- may be explicitly indicates to change from the MeNB) 1 to MeNB (T-MeNB) 3. For example, SeNB Addition, Request message, may be added to SCG Change Indication IE. Furthermore, the new Cause values ​​of SCG Change Indication IE (eg, Inter MeNB Handover, SeNB (SCG) Stored Handover) is defined, SeNB Addition, Request message may specify the Cause value. In this case, the additional information element, the bearer identifier (eg, E-RAB ID or eps-Bearer Identity for UE4 already set in SeNB2 for DC in conjunction with MeNB1, DRB Identity, or it may indicate that these combinations) is not changed.
[0060]
　In step 303, SeNB2, while offering SCG for a DC to specific UE4 in conjunction with MeNB (S-MeNB) 1, SeNB Addition Request message including the additional information elements described above (step 302 ) in response to receiving, the SeNB Addition, request message, recognizes that the requesting modifying the (changing) the settings for already SCG that is set for the DC in conjunction with S-MeNB1 (consider) It is configured. Configuration modifications (changes) of about SCG, for example, (a) SCG MeNB settings associated with (eg, MeNB UE X2AP ID) modification (change), (b) associated with the SCG of MCG or MCG bearer configuration modifications (changes), including at least one of, modification of (c) SeNB security key (S-KeNB) (changed), and (d) SCG or SCG bearer or modify settings of the split bearer (change). As a more specific example, SeNB2 is, SeNB Addition Request E-RAB To Be Added List IE message, already same value that is set for UE4 doing a DC between S-MeNB1 If the wireless terminal identifier (eg, SeNB UE X2AP ID), and a E-RAB ID of the same value as that set for the UE4, modifications of setting the SeNB Addition, Request corresponds to the E-RAB (change), or recognizes that a reconfiguration of SCG including the E-RAB.
[0061]
　In step 304, SeNB2, based on the information (eg, SCG-ConfigInfo) from T-MeNB3 contained SeNB Addition, Request message (step 302), generates a new SCG set (SCG-Config), the new response message (SeNB Addition Request Acknowledge) to send to the T-MeNB3 encompasses such SCG settings. The new SCG settings may include terminal identifier assigned to UE4 by SeNB2 to uniquely identify the UE4 in SCG (C-RNTI). SeNB2 is, SCG in addition to the case of SCG established (SCG establishment), SCG modifications accompanying MeNB change (change) · SCG reestablishment (SCG re-establishment) · or SCG relocation (SCG relocated, SCG relocation) in the case of the "MobilityControlInfoSCG" information element in the configuration may be always added to C-RNTI.
[0062]
　Incidentally, in the abnormality condition (Abnormal the Conditions) on the procedures shown in FIG. 3, SeNB2 and T-MeNB3 may operate as follows. If SeNB Addition, Request message wireless terminal identifier indicated by (step 302) (ie, SeNB UE X2AP ID) is S-MeNB1 and between base stations during SeNB2 interface (ie, X2 interface) uniquely specifying for the UE4 in If not used, SeNB2 may transmit the SeNB Addition, Request Reject message instead of SeNB Addition, Request Acknowledge message (step 304). The SeNB Addition, Request Reject message indicates that unacceptable the SeNB Addition, Request message (step 302). The SeNB Addition, Request Reject message may include a Cause value (eg, Inappropriate X2AP ID) indicating that the requested wireless terminal identifier (ie, SeNB UE X2AP ID) is inappropriate. Alternatively, if the functions required for inter-eNB handover of DC UE it will always have the SCG SeNB2 does not support, SeNB Addition, Request Reject message, Cause value indicative thereof (eg, "Bearer Keeping Option Not Supported" , "Bearer Keeping Handover Not supported") may contain a.
[0063]
　T-MeNB3 in response to reception of the SeNB Addition, Request Reject message, the response message indicating that not accept handover (Handover Preparation Failure message) may be sent to the S-MeNB1. Alternatively, T-MeNB3 is the E-RABs Not Admitted List IE in Handover Request Acknowledge message may include the E-RAB ID bearer (SCG bearer or split bearer) of the SeNB. In this case, S-MeNB1 instructs the handover to UE4 (RRC Connection Reconfiguration including mobility Control Info) cancel or handover before sending the (interruption), may be released to SCG, MCG and SCG bearer it may be changed to the bearer.
[0064]
　Figure 4 is a flowchart showing an example of the operation of SeNB2 the (process 400). In block 401, SeNB2, while offering SCG for a DC to specific UE4 in conjunction with MeNB (S-MeNB) 1, the SeNB Addition, Request message to another eNB (T-MeNB) 3 It received. If at block 402, S-MeNB1 set by SeNB2 to uniquely identify the specific UE4 in DC and have been UE ID (eg, SeNB UE X2AP ID) that is the SeNB Addition, Request message (block 401) comprising recognizes SeNB2 is the SeNB Addition, request message already have been set SCG (SCG Config, or bearer (eg, E-RAB)) and a request for modification (change).
[0065]
　As understood from the above description, according to the example described with reference to FIGS. 3 and 4, SeNB2 is the SCG for a DC to specific UE4 in conjunction with MeNB (S-MeNB) 1 while providing, when receiving the SeNB Addition, Request message from another eNB (T-MeNB) 3, it can be distinguished the SeNB Addition, Request message with an existing (conventional) SeNB Addition, Request message. Therefore, it is possible to prevent the judged SeNB Addition, Request message received from the T-MeNB3 the error cases (error Case), to release or SCG or ignore it (or bearer).
[0066]
　Incidentally, in response to receiving the SeNB Addition, Request message from the T-MeNB3, SeNB2 may further operate as follows. In some implementations, SeNB2, in response to sending the SeNB Addition, Request Acknowledge message to the T-MeNB3, modified for DC to the SCG set in conjunction with T-MeNB3 for DC in conjunction with S-MeNB1 been SCG set (or newly set SCG set) may be configured to replace the.
[0067]
　Alternatively, SeNB2 is, SeNB Release Request message (step 205) in response to receiving from the S-MeNB1, for DC to the SCG set in conjunction with T-MeNB3 for DC in conjunction with S-MeNB1 modified SCG settings (or newly set SCG set) may be configured to replace the.
[0068]
　In some implementations, SeNB2, in response to reception of the SeNB Addition, Request message from the T-MeNB3, is configured to stop receiving, or both user data from the transmission or UE4 user data to UE4 it may be.
[0069]

　In the procedure shown in FIGS. 2A and 2B, SeNB2 is, SeNB Release Request message from the S-MeNB1 (step 205) and UE Context Release message (step 219) the existing (conventional ) SeNB Release Request and UE Context Release message must be distinguished. Since these SeNB Release Request and UE Context Release message (steps 205 and 219) is to allow the release of only some SeNB2 among resources associated to the UE context of UE4, thus existing (usually ) SeNB Release Request and UE Context Release message with but have different roles.
[0070]
　In the present embodiment, FIGS. 2A and 2B at the indicated SeNB Release Request message (step 205) and UE Context Release message S-MeNB1 to distinguish (step 219) and existing (ordinary) message, SeNB2, and specific examples of operations and message composition of the T-MeNB3 is described.
[0071]
　5, SeNB2 is after receiving the SeNB Addition, Request message from the T-MeNB3, it shows an example of a procedure of receiving the SeNB Release Request message from the S-MeNB1 a (Step 500). Step 501 to 504 shown in FIG. 5 are the same as steps 301-304 shown in FIG. Step 505 and 506 shown in FIG. 5 corresponds to the step 204 and 205 shown in Figure 2A. That is, in step 505, T-MeNB3 transmits a handover request response message indicating acceptance of (step 501) (Handover Request Acknowledge) to the S-MeNB1.
[0072]
　In step 506, in response to receiving the Handover Request Acknowledge message, S-MeNB1 transmits the SeNB Release Request message to SeNB2. The SeNB Release Request message triggers resource (eg, UE context) as SeNB about UE4 for DC and S-MeNB1 release of the SeNB2.
[0073]
　In step 507, SeNB2, after accepting the SeNB Addition, Request (step 502) from the T-MeNB3, SeNB Release Request message (step 506) when received from the S-MeNB1, associated with the UE context of the UE4 While some of the resources can be freed recognizes that it should maintain the remaining resources.
[0074]
　In other words, SeNB2 is before the receiving of the SeNB Release Request message (step 506) from the S-MeNB1, T-MeNB3 that are considered requests modifications to SCG or bearer (E-RAB) for the DC the UE4 If that accepted SeNB Addition, Request from (step 503), but can release some of the resources associated to the UE context UE4 recognize that it should maintain the remaining resources.
[0075]
　In other words Furthermore, SeNB2 is, S-MeNB1 SeNB from Release Request message before the receiving of (step 506), that the MeNB of DC for UE4 is changed to T-MeNB3 from S-MeNB1 T- if it was explicitly or implicitly signaled from MeNB3 (step 502), but can release some of the resources associated to the UE context UE4 recognize that it should maintain the remaining resources.
[0076]
　In some implementations, SeNB2, in response to reception of the SeNB Release Request message (step 506) from the S-MeNB1, some resources of the radio resources and control plane resources associated to the UE context of the UE4 You may recognize that can release should maintain the remaining resources. The released part may be a resource, for example, one or more identifiers of the base station between the interface connection between the S-MeNB1 and SeNB2 associated with UE4 (X2 interface connection) (eg, S-MeNB1 including MeNB UE X2AP ID) assigned by. Remaining resources not to be released, for example, a bearer setting at SCG associated with UE4. The bearer setting, for example, the bearer identifier (eg, E-RAB ID or eps-Bearer Identity, DRB Identity, or a combination of these), including a logical channel set, and Radio Link Control (RLC) configuration. The bearer configuration may be set that is updated based on the SeNB Addition, Request from T-MeNB3.
[0077]
　Additionally or alternatively, in some implementations, SeNB2 the data forwarding in response to reception of the SeNB Release Request message (step 506) from the S-MeNB1, the S-MeNB1 (or T-MeNB3) from SeNB2 You may recognize that it should maintain the state of the user data of UE4 also not be necessary. State related to the user data includes, for example, Packet data Convergence Protocol (PDCP) status (eg, PDCP SN and HFN) of the user data of UE4 at least one of and Radio Link Control (RLC) status.
[0078]
　Figure 6 is a flowchart showing an example of the operation of SeNB2 the (process 600). In block 601, SeNB2, while offering SCG for a DC to specific UE4 in conjunction with MeNB (S-MeNB) 1, receives the SeNB Release Request message from the S-MeNB1. At block 602, SeNB2 is before the receiving of the SeNB Release Request message from the S-MeNB1 (block 601), considered a modification request for the SCG or bearer (E-RAB) for the DC the UE4 (change) recognizing when not accept SeNB Addition, request from T-MeNB3 that, as the SeNB release request message is a request that triggers the release of only a portion of the resources for that particular UE4. For example, SeNB2 is, E-RAB To Be Released List IE received in SeNB Release Request message is requesting additional from T-MeNB3 (i.e., specified by SeNB Addition, Request message), SeNB2 has accepted (that is, the required to accept the) as the same bearer identifier (eg, if it contains E-RAB ID), SeNB2 is the SeNB release message, to trigger the release of only a portion of the resources of the E-RAB corresponding (about UE4) We recognize that is a request.
[0079]
　As understood from the above description, according to the example described with reference to FIGS. 5 and 6, SeNB2 is the SCG for a DC to specific UE4 in conjunction with MeNB (S-MeNB) 1 while providing the SeNB Release Request message when received from the S-MeNB1, based on whether the already accepted the SeNB Addition, Request from T-MeNB3, in response to the reception of the SeNB Release Request message released can be recognized better resource even. Therefore, when the SeNB (or SCG, or bearer (SCG bearer or split bearer) of SCG) MeNB changes while maintaining the (MeNB handover) is performed, it continues to be used for DC in conjunction with T-MeNB3 that the resource can be prevented from being released (deleted (the remove)).
[0080]

　In the present embodiment, a modification of the second embodiment is described. Procedures and operations described with reference to FIGS. 5 and 6, instead of or in addition to the time of reception by SeNB2 the SeNB Release Request message from the S-MeNB1, upon reception by SeNB2 the UE Context Release message from the S-MeNB1 it may be performed. 7, SeNB2 is later received the SeNB Addition, Request message from the T-MeNB3, it shows an example of a procedure of receiving the SeNB UE Context Release message from the S-MeNB1 a (Step 700). Step 701-704 shown in FIG. 7 are the same as steps 501-504 shown in steps 301-304 and 5 shown in FIG.
[0081]
　Step 705 and 706 shown in FIG. 7 corresponds to the step 218 and 219 shown in Figure 2B. That is, in step 705, T-MeNB3 sends a UE Context Release message to the S-MeNB1. In step 706, S-MeNB1 in response to the reception of the UE Context Release message from the T-MeNB3, sends a UE Context Release message to SeNB2.
[0082]
　In step 707, SeNB2, after accepting the SeNB Addition, Request (step 702) from the T-MeNB3, UE Context Release message (step 706) when received from the S-MeNB1, associated with the UE context of the UE4 While some of the resources can be freed recognizes that it should maintain the remaining resources.
[0083]
　In other words, SeNB2 is before the receiving of the UE Context Release message (step 706) from the S-MeNB1, T-MeNB3 that are considered requests modifications to SCG or bearer (E-RAB) for the DC the UE4 If that accepted SeNB Addition, Request from (step 703), but can release some of the resources associated to the UE context UE4 recognize that it should maintain the remaining resources.
[0084]
　In other words Furthermore, SeNB2 is, S-MeNB1 UE Context Release message from before the reception of the (step 706), that the MeNB of DC for UE4 is changed to T-MeNB3 from S-MeNB1 T- if it was explicitly or implicitly signaled from MeNB3 (step 702), but can release some of the resources associated to the UE context UE4 recognize that it should maintain the remaining resources.
[0085]
　According to the example described with reference to FIG. 7, SeNB2, while offering SCG for a DC to specific UE4 in conjunction with MeNB (S-MeNB) 1, a UE Context Release message S when receiving from -MeNB1, based on whether the already accepted the SeNB Addition, Request from T-MeNB3, can also recognize the good resources to release in response to the reception of the UE Context release message. Therefore, when the SeNB (or SCG, or bearer (SCG bearer or split bearer) of SCG) MeNB changes while maintaining the (MeNB handover) is performed, it continues to be used for DC in conjunction with T-MeNB3 that the resource can be prevented from being released (deleted (the remove)).
[0086]
　In the example described with reference to FIGS. 5 to 6, S-MeNB1 is the SeNB Release Request message or UE Context Release message, MeNB of DC for the UE is changed to T-MeNB3 from S-MeNB1 it may be included explicitly indicate information element. Additionally or alternatively, S-MeNB1 is the SeNB Release Request message or UE Context Release message, the resource partial release of associated with UE context UE4 (ie, partial SeNB Release Request or partials UE Context Release ) may include an information element indicating the. These information elements can be a Cause information element indicating the cause of the release message (SeNB Release Request message or UE Context Release message). For example, "Inter MeNB Handover", "Optimized Handover", or "Control plane release" the new show a Cause value / Cause names may be defined. Thus, SeNB2 can be easily distinguished and the SeNB Release Request message or UE Context Release message including these information elements existing (conventional) SeNB Release Request message or UE Context Release message.
[0087]
　Finally, eNB1 according to embodiments described above, eNB2, eNB 3, and configuration examples of UE4 is described. Figure 8 is a block diagram showing a configuration example of SeNB2. S-MeNB1 and T-MeNB3 also may have a configuration similar to that of FIG. Referring to FIG. 8, SeNB2 includes an RF transceiver 801, network interface 803, processor 804, and memory 805. RF transceiver 801 performs analog RF signal processing to communicate with the UEs. RF transceiver 801 may include a plurality of transceivers. RF transceiver 801 is coupled to the antenna 802 and the processor 804. RF transceiver 801 receives the modulated symbol data (or OFDM symbol data) from processor 804, generates a transmission RF signal and provides a transmit RF signal to the antenna 802. Also, RF transceiver 801 generates a baseband received signal based on the reception RF signal received by the antenna 802, and supplies it to the processor 804.
[0088]
　Network interface 803 is used for communicating network nodes (eg, other eNBs, MME, and S-GW) and. Network interface 803 may include, for example, a network interface card that complies with the IEEE 802.3 series (NIC).
[0089]
　The processor 804 performs data plane processing and control plane processing including digital baseband signal processing for wireless communication. For example, in the case of LTE and LTE-Advanced, a digital baseband signal processing by the processor 804, PDCP layer, RLC layer may include a signal processing of the MAC layer, and the PHY layer. Further, the signal processing by the processor 804 may include signal processing GTP-U · UDP / IP layer in the X2-U interface and S1-U interface. The control plane processing by the processor 804, X2AP protocol may include a process of S1-MME protocol and the RRC protocol.
[0090]
　The processor 804 may include multiple processors. For example, the processor 804, a modem processor that performs digital baseband signal processing (eg, DSP), X2-U interface and S1-U interface of the GTP-U · UDP / IP layer processor for performing signal processing (eg, DSP), and a protocol stack processor for performing control plane processing (eg, may include a CPU or MPU).
[0091]
　Memory 805 is composed of a combination of volatile and nonvolatile memory. Memory 805 may include a physically independent plurality of memory devices. Volatile memory may be, for example, Static Random Access Memory (SRAM) or Dynamic RAM (DRAM) or a combination thereof. The non-volatile memory, a mask Read Only Memory (MROM), Electrically Erasable Programmable ROM (EEPROM), flash memory, or hard disk drive, or any combination thereof. Memory 805 may include a storage that is remotely located from the processor 804. In this case, the processor 804 may access the memory 805 via the I / O interfaces that are not network interface 803 or illustrated.
[0092]
　Memory 805 may store software modules (computer program) including instructions and data for processing by SeNB2 described in several embodiments described above. In some implementations, the processor 804, the software module that executes from the memory 805 may be configured to perform processing of SeNB2 described in the above embodiments.
[0093]
　Figure 9 is a block diagram showing a configuration example of UE4. Radio Frequency (RF) transceiver 901 performs analog RF signal processing to communicate with the eNB2. Analog RF signal processing performed by the RF transceiver 901 includes a frequency up-conversion, the frequency down-conversion, and amplification. RF transceiver 901 is coupled to the antenna 902 and the baseband processor 903. That, RF transceiver 901 receives the modulated symbol data (or OFDM symbol data) from the baseband processor 903 generates a transmission RF signal and provides a transmit RF signal to the antenna 902. Also, RF transceiver 901 generates a baseband received signal based on the reception RF signal received by the antenna 902, and supplies it to the baseband processor 903.
[0094]
　Baseband processor 903 performs control plane processing and digital baseband signal processing for wireless communication (data plane processing). Digital baseband signal processing, (a) data compression / decompression, (b) segmentation / concatenation of data, generation / decomposition of (c) transmission format (transmission frame), (d) transmission channel coding / decoding , including generation of (e) modulation (symbol mapping) / demodulation, and OFDM symbol data by (f) Inverse Fast Fourier Transform (IFFT) (baseband OFDM signal). On the other hand, the control plane processing, layer 1 (eg, transmission power control), Layer 2 (eg, radio resource management, and hybrid automatic repeat request (HARQ) process), and layer 3 (eg, attach, mobility and call management including communication management signaling) related.
[0095]
　For example, in the case of LTE and LTE-Advanced, a digital baseband signal processing by the baseband processor 903, Packet Data Convergence Protocol (PDCP) layer, Radio Link Control (RLC) layer, includes a signal processing of the MAC layer, and a PHY layer But good. Further, the control plane processing by the baseband processor 903, Non-Access Stratum (NAS) protocol, RRC protocol, and may include a process of MAC CE.
[0096]
　The baseband processor 903, a modem processor that performs digital baseband signal processing (eg, Digital Signal Processor (DSP)) and protocol stack processor for performing control plane processing (eg, Central Processing Unit (CPU), or Micro Processing Unit it may include (MPU)). In this case, the protocol stack processor for performing control plane processing may be shared with the application processor 904 to be described later.
[0097]
　Application processor 904, CPU, MPU, also referred to as a microprocessor or processor cores. The application processor 904 may include a plurality of processors (multiple processor cores). Application processor 904, memory 906 or illustrated which do not result system read from the memory a software program (Operating System (OS)) and various application programs (e.g., call application, WEB browser, a mailer, a camera operation application, music playback by running the application), to implement the various functions of UE4.
[0098]
　In some implementations, as shown in dashed lines (905) in FIG. 9, the baseband processor 903 and application processor 904 may be integrated on a single chip. In other words, the baseband processor 903 and application processor 904 may be implemented as a single System on Chip (SoC) device 905. SoC devices, sometimes referred to as system Large Scale Integration (LSI) or chipset.
[0099]
　Memory 906 is a volatile memory or nonvolatile memory, or a combination thereof. Memory 906 may include a physically independent plurality of memory devices. Volatile memory may be, for example, Static Random Access Memory (SRAM) or Dynamic RAM (DRAM) or a combination thereof. The non-volatile memory, a mask Read Only Memory (MROM), Electrically Erasable Programmable ROM (EEPROM), flash memory, or hard disk drive, or any combination thereof. For example, memory 906, baseband processor 903, application processor 904, and may include accessible external memory device from SoC905. Memory 906, within the baseband processor 903, within the application processor 904, or may include an integrated chip memory device within SoC905. Furthermore, memory 906 may include a memory in the Universal Integrated Circuit Card (UICC).
[0100]
　Memory 906 may store software modules (computer program) including instructions and data for processing by the UE4 described in several embodiments described above. In some implementations, the baseband processor 903 or the application processor 904, the software module that executes from the memory 906 may be configured to perform processing of UE4 described in the above embodiments.
[0101]
　As described with reference to FIGS. 8 and 9, each of the processors eNB1, eNB2, eNB 3, and UE4 have according to the above-described embodiments, instructions for performing the algorithm described with reference to the drawings in the computer perform one or more programs including the group. This program is stored using a non-transitory computer readable media of various types (non-transitory computer readable medium), it can be supplied to the computer. Non-transitory computer readable media include with various types of entities (tangible storage medium). Examples of non-transitory computer readable media include magnetic storage media (such as floppy disks, magnetic tape, hard disk drive), magneto-optical recording medium (e.g., magneto-optical disk), Compact Disc Read Only Memory (CD-ROM), CD- R, including CD-R / W, a semiconductor memory (e.g., a mask ROM, Programmable ROM (PROM), Erasable PROM (EPROM), flash ROM, Random Access memory (RAM)). The program may be provided to a computer using a temporary computer readable media of various types (transitory computer readable medium). Examples of transitory computer readable media include electric signals, optical signals, and electromagnetic waves. Transitory computer readable media, wired communication path such as electrical wires and optical fibers, or via a wireless communication path can provide the program to a computer.
[0102]

　The above-described embodiments have mainly described LTE / LTE-Advanced and improvements. However, the above-described embodiments may be applied to other wireless communication network or system. Each eNBs1 ~ 3 described in the above embodiments may also be referred to as a radio station. Radio station herein, the control node (eg, Radio Network Controller in the UMTS (RNC), or Base Station Controller in GSM system (BSC)), and a radio transmission node having a radio resource management functions (eg, NodeB in UMTS, or it may comprise a Base transceiver station (BTS)) in the GSM system.
[0103]
　Furthermore, the above-described embodiments are only examples for the application of technical ideas obtained by the present inventor. In other words, the technical idea is not limited to the embodiments described above, it is needless to say various modifications are possible.
[0104]
　For example, some or all of the above embodiments, can be described as the following notes, not limited to the following.
[0105]
(Note A1)
　and at least one wireless transceiver
　and at least one processor coupled to the at least one radio transceiver,
comprising a
　at least one processor is for dual connectivity in conjunction with the first master base station when receiving the SeNB addition request message from the second master base station while providing the secondary cell group (SCG) to the wireless terminal, the SeNB addition request message of the dual connectivity for the wireless terminal in response to the master base station includes explicitly or implicitly the first information element indicating that the change to the second master base station from the first master base station, the SeNB addition request message It is configured to recognize the requesting modification of settings related to the SCG,
base station apparatus.
[0106]
(Supplementary Note A2)
　said first information element is to indicate the change of the master base station for dual connectivity for the wireless terminal implicitly, between the first master base station and the base station apparatus in the base station between interfaces including said wireless terminal identifier assigned by the base station apparatus to uniquely identify the wireless terminal,
a base station apparatus according to Appendix A1.
[0107]
(Supplementary Note A3)
　the radio terminal identifier includes SeNB UE X2AP ID assigned by the base station apparatus,
the base station apparatus according to Appendix A2.
[0108]
(Supplementary Note A4)
　the first information element further bearer identifier and the same bearer identifier of a network bearer already set in the base station apparatus for the dual connectivity in conjunction with the first master base station including,
a base station apparatus according to note A2 or A3.
[0109]
(Supplementary Note A5)
　the first information element is explicitly said dual connectivity of the master base station for the wireless terminal is changed to the second master base station from the first master base station shown,
the base station apparatus according to Appendix A1.
[0110]
(Supplementary Note A6)
　the SeNB addition request message, the combination of the bearer identifiers of the data radio bearer of the network bearers already set in the base station apparatus for a first of said dual connectivity in conjunction with the master base station It includes information specifying a combination of the same bearer identifier,
the base station apparatus according to Appendix A5.
[0111]
(Supplementary Note A7)
　wherein the at least one processor, the response message to SeNB addition request message in response to transmitting the second master base station, the dual connectivity in conjunction with the first master base station and is configured to replace the modified or newly set SCG set for dual connectivity to the SCG set in conjunction with the second master base station for,
according to any one of appendices A1 ~ A6 the base station apparatus.
[0112]
(Supplementary Note A8)
　wherein the at least one processor, in response to the SCG release request message received from the first master base station, the SCG setting for the dual connectivity in conjunction with the first master base station the second is configured to replace the modified SCG set for dual connectivity in conjunction with the master base station,
the base station apparatus according to any one of appendices A1 ~ A6.
[0113]
(Supplementary Note A9)
　wherein the at least one processor is said SeNB addition request message in response to receiving from the second master base station, the user data from a transmission or the wireless terminal of the user data to the radio terminal receiving or both of these is configured to stop,
the base station apparatus according to any one of appendices A1 ~ A8.
[0114]
(Supplementary Note A10)
　the at least one processor, said after accepting the SeNB addition request message from the second master base station, said release message that triggers the release of the context of the wireless terminal for the dual connectivity when received from the first master base station, said can release some of the resources of the radio resources and control plane resources associated with the context of the wireless terminal should maintain a remaining resource and is configured to recognize,
the base station apparatus according to any one of appendices A1 ~ A9.
[0115]
(Supplementary Note A11)
　wherein part of the resources include one or more identifiers of the base station between the interface connection between the first master base station and the base station apparatus associated with the wireless terminal,
Appendix A10 the base station apparatus according to.
[0116]
(Supplementary Note A12)
　the remaining resource includes setting of bearers associated to the wireless terminal,
a base station apparatus according to note A10 or A11.
[0117]
(Supplementary Note A13)
　setting of the bearer identifier of the bearer, logical channel set, and Radio including Link Control (RLC) setting,
the base station apparatus according to Appendix A12.
[0118]
(Supplementary Note A14)
　setting of the bearer, the second based on the SeNB addition request from the master base station is updated,
the base station apparatus according to note A12 or A13.
[0119]
(Supplementary Note A15)
　the at least one processor, said after accepting the SeNB addition request message from the second master base station, said release message that triggers the release of the context of the wireless terminal for the dual connectivity when received from the first master base station, even if not required data forwarding from the base station apparatus to the first or the second master base station should maintain state about the user data of the wireless terminal is configured to recognize that,
the base station apparatus according to any one of appendices A1 ~ A14.
[0120]
(Supplementary Note A16)
　the state of the user data, at least one including, among Packet data Convergence Protocol (PDCP) status and Radio Link Control (RLC) status of the user data of the wireless terminal
base station apparatus according to Appendix A15.
[0121]
(Supplementary Note A17)
　said release message, SCG release request message indicating the release of the SCG, or the a context release message indicating the release of the context for the wireless terminal,
a base station apparatus according to any one of Appendices A10 ~ A16 .
[0122]
(Supplementary Note A18)
　said release message, explicitly indicating second that the dual connectivity of the master base station is changed to the second master base station from the first master base station for the wireless terminal information element, or the third information element indicating a partial release of resources associated with the context of the wireless terminal, or both of these,
the base station apparatus according to any one of appendices A10 ~ 17.
[0123]
(Supplementary Note A19)
　wherein at least one of the second information element and the third information element includes Cause information element indicating the cause of the release message,
the base station apparatus according to Appendix A18.
[0124]
(Supplementary Note B1)
　and at least one wireless transceiver
　and at least one processor coupled to the at least one radio transceiver,
comprising a
　at least one processor is
　for dual connectivity in conjunction with the first master base station is configured to the said receiving the release message to trigger the release of the context of the wireless terminal from the first master base station for dual connectivity while the offering secondary cell group (SCG) to the wireless terminal ,
　wherein before receiving the release message, the said dual connectivity master base station and the second to be changed from the first master base station to the second master base station for the wireless terminal if it was explicitly or implicitly signaled from the master base station, upon receipt of the release message The can release some of the resources of the radio resources and control plane resources associated with the context of the wireless terminals are configured to recognize that it should maintain the remaining resources,
the base station apparatus .
[0125]
(Supplementary Note B2)
　wherein a portion of the resources include one or more identifiers of the base station between the interface connection between the first master base station and the base station apparatus associated with the wireless terminal,
Appendix B1 the base station apparatus according to.
[0126]
(Supplementary Note B3)
　the remaining resource includes setting of bearers associated to the wireless terminal,
a base station apparatus according to note B1 or B2.
[0127]
(Supplementary Note B4)
　setting of the bearer identifier of the bearer, logical channel set, and Radio including Link Control (RLC) setting,
the base station apparatus according to Appendix B3.
[0128]
(Supplementary Note B5)
　setting of the bearer, the second based on the SeNB addition request from the master base station is updated,
the base station apparatus according to note B3 or 4.
[0129]
(Supplementary Note B6)
　at least one radio transceiver
　and at least one processor coupled to the at least one radio transceiver,
comprising a
　at least one processor is
　for dual connectivity in conjunction with the first master base station is configured to the said receiving the release message to trigger the release of the context of the wireless terminal from the first master base station for dual connectivity while the offering secondary cell group (SCG) to the wireless terminal ,
　wherein before receiving the release message, the said dual connectivity master base station and the second to be changed from the first master base station to the second master base station for the wireless terminal if it was explicitly or implicitly signaled from the master base station, upon receipt of the release message The first or the data forwarding to the second master base station even if not necessary the is configured to recognize that it should remain about the user data of the wireless terminal,
the base station apparatus.
[0130]
(Supplementary Note B7)
　the state of the user data, said at least one of Packet data Convergence Protocol (PDCP) status and Radio Link Control (RLC) status of the user data of the wireless terminal,
a base station apparatus according to Appendix B6.
[0131]
(Supplementary Note B8)
　said release message, SCG release request message indicating the release of the SCG, or the a context release message indicating the release of the context for the wireless terminal,
a base station apparatus according to any one of Appendices B1 ~ B7 .
[0132]
(Supplementary Note B9)
　said release message, explicitly indicating second that the dual connectivity of the master base station is changed to the second master base station from the first master base station for the wireless terminal information element, or the third information element indicating a partial release of the radio resources and control plane resources associated with the context of the wireless terminal, or both of these,
any one of appendices B1 ~ B8 the base station apparatus according to.
[0133]
(Supplementary Note B10)
　wherein at least one of the second information element and the third information element includes Cause information element indicating the cause of the release message,
the base station apparatus according to Appendix B9.
[0134]
　This application claims priority based on 2015 July 31, 2008 Japanese Patent Application No. 2015-152735, filed on, the entire disclosure of which is incorporated herein.
DESCRIPTION OF SYMBOLS
[0135]
1-3 Base station
(eNBs) 4 radio terminal
(UE) 801 RF transceiver
804 processor
805 memory

claims

[Claim 1]And at least one wireless transceiver
　and at least one processor coupled to the at least one radio transceiver,
comprising a
　at least one processor, a secondary cell for dual connectivity in conjunction with the first master base station, when receiving the SeNB addition request message from the second master base station while providing the group (SCG) to the wireless terminal, the SeNB addition request message is a master base station of the dual connectivity for the wireless terminal in response to include an explicit or implicitly indicate the first information element to be changed to the second master base station from the first master base station, set the SeNB addition request message is related to the SCG It is configured to recognize the requesting of modification,
the base station apparatus.
[Claim 2]
　The first information element, said dual connectivity for changes in the master base station to indicate implicitly the said first base station between the interface between the master base station wherein the base station apparatus for the radio terminal in including the wireless terminal identifier where the allocated by the base station apparatus to uniquely identify a wireless terminal,
a base station apparatus according to claim 1.
[Claim 3]
　It said wireless terminal identifier includes SeNB UE X2AP ID assigned by the base station apparatus,
the base station apparatus according to claim 2.
[Claim 4]
　The first information element further comprises a same bearer identifier and the bearer identifier of the network bearers already set in the base station apparatus for said first of said dual connectivity in conjunction with the master base station,
claim the base station apparatus according to 2 or 3.
[Claim 5]
　The first information element is expressly indicate that the dual connectivity of the master base station for the wireless terminal is changed to the second master base station from the first master base station,
claim the base station apparatus as claimed in 1.
[Claim 6]
　Wherein the at least one processor, in response to sending a reply message to the SeNB addition request message to the second master base station, SCG setting for the first of the dual connectivity in conjunction with the master base station the is configured to replace the modified or newly set SCG set for dual connectivity in conjunction with the second master base station,
the base station according to any one of claims 1 to 5 apparatus.
[Claim 7]
　Wherein the at least one processor, in response to the SeNB release request message received from the first master base station, said SCG setting the second for the first of the dual connectivity in conjunction with the master base station and it is configured to replace the modified SCG set for dual connectivity in conjunction with the master base station,
the base station apparatus according to any one of claims 1 to 5.
[8.]
　Wherein the at least one processor, said after accepting the SeNB addition request message from the second master base station, SeNB release request message said first master base station to trigger the release of resources for the dual connectivity when receiving from said although some resources of the radio resources and control plane resources associated with the context of the wireless terminal can release is configured to recognize that it should maintain the remaining resources ,
the base station apparatus according to any one of claims 1 to 7.
[Claim 9]
　The special resource, including one or more identifiers of the base station between the interface connection between the first master base station and the base station apparatus associated with the wireless terminal,
according to claim 8 base station apparatus.
[Claim 10]
　The remaining resources include setting of bearers associated to the wireless terminal,
a base station apparatus according to claim 8 or 9.
[Claim 11]
　Setting of the bearer identifier of the bearer, logical channel set, and Radio including Link Control (RLC) setting,
the base station apparatus according to claim 10.
[Claim 12]
　Wherein the at least one processor, said after accepting the SeNB addition request message from the second master base station, SeNB release request message said first master base station to trigger the release of resources for the dual connectivity to recognize that when receiving, it should also maintain state about the user data of the wireless terminal data forwarding is not required from the base station apparatus to the first or the second master base station from is configured,
the base station apparatus according to any one of claims 1 to 11.
[Claim 13]
　The state of the user data, said at least one of Packet data Convergence Protocol (PDCP) status and Radio Link Control (RLC) status of the user data of the wireless terminal,
a base station apparatus according to claim 12.
[Claim 14]
　The SeNB release request message, wherein the dual connectivity second information indicating explicitly to be changed to the second master base station master base station from the first master base station for the wireless terminal element, or the third information element indicating a partial release of resources associated with the context of the wireless terminal, or both of these,
the base station apparatus according to any one of claims 8-13.
[Claim 15]
　A method in a secondary base station,
　SeNB added from the second master base station while providing secondary cell group for dual connectivity in conjunction with the first master base station (SCG) to the wireless terminal receiving a request message, and
　clearly to be changed to the SeNB addition request message is the second master base station wherein dual connectivity of the master base station from the first master base station for the wireless terminal in response to include a first information element, it, to recognize that the SeNB addition request message is requesting modification of settings related to the SCG showing or implicit
method comprising a.
[Claim 16]
　The non-transitory computer readable medium storing a program for causing a process in the secondary base station to the computer,
　the method comprising
　the secondary cell group for dual connectivity in conjunction with the first master base station receiving a SeNB addition request message from the second master base station while providing the (SCG) to the wireless terminal, and
　the SeNB addition request message is a master base station of the dual connectivity for the wireless terminal in response to include an explicit or implicitly indicate the first information element to be changed to the second master base station from the first master base station, set the SeNB addition request message is related to the SCG recognizing the requesting modifications,
including,
non-transitory computer readable media.
[Claim 17]
　A wireless terminal,
　the first master base station, the second master base station, and at least one radio transceiver for communicating with the secondary base station,
　and at least one processor
comprises a,
　the secondary base station , SeNB added from the second master base station while the secondary base station is providing the secondary cell group (SCG) for dual connectivity in conjunction with the first master base station to said wireless terminal when receiving the request message, explicit that the SeNB addition request message is changed to the second master base station wherein dual connectivity of the master base station from the first master base station for the wireless terminal or in response to include a first information element indicating implicitly, the SeNB addition request message is requesting modification of settings related to the SCG Is configured to recognize and that,
　while the at least one processor communicates with the first master base station and the second master base station, to maintain a connection to the SCG of the secondary base station the is configured to change the second master base station master base station dual connectivity from the first master base station,
the wireless terminal.