JP2016129414A - Mobile communication method, mobile station, and wireless base station - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a reconnection procedure to succeed even if a wireless base station to be connected to does not manage a "UE Context" related to a mobile station UE.SOLUTION: A mobile communication method includes: a step B in which a mobile station UE transmits a CGI of a cell #1 to a wireless base station eNB#2 in a reconnection procedure; and a step C in which the wireless base station eNB#2 acquires a "UE Context" related to the mobile station UE from a wireless base station eNB#1, which manages the cell #1 specified on the basis of the CGI, in the reconnection procedure, if the wireless base station eNB#2 does not manage the "UE Context" related to the mobile station UE.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a mobile communication method, a mobile station, and a radio base station.

In recent years, “Heterogeneous Network (HetNet)” has been studied as one of the methods for increasing the network capacity with respect to continuously increasing traffic.

In “HetNet”, the capacity of the entire network can be increased by arranging a plurality of picocells in a conventional macrocell and absorbing traffic such as hot spots in the picocell while guaranteeing coverage in the macrocell.

Thus, when a large number of pico cells are arranged, one macro cell (radio base station eNB
) Within the area (or surrounding area), the same PCI (Physical Cell I)
There may be many picocells using (dentity). Therefore, there is a problem that a macro cell (radio base station eNB) cannot uniquely identify neighboring pico cells by only PCI.

Note that handover from a macro cell to a pico cell (or femto cell), so-called,
For the "PCI confusion problem" in "inbound HO"
A solution is defined in the Release-9 method of TE (Long Term Evolution).

According to such a solution, by reporting CGI (Cell Global Identity) of the surrounding picocell (femtocell) whose reception quality is improved from the mobile station UE,
The handover destination cell can be uniquely determined by the macro cell (radio base station eNB).

  FIG. 6 shows a reconnection procedure in the LTE Release 8/9/10 system.

As shown in FIG. 6, in the LTE Release 8/9/10 system, step S3001 is performed.
The mobile station UE performs RLF (Rad) in the cell # 1 under the control of the radio base station eNB # 1.
When (io Link Failure, radio link failure) is detected, a reconnection procedure for the radio base station eNB # 2 that manages the cell # 2 selected by the cell selection process is started.

At this time, the reconnection-destination radio base station eNB # 2 performs “UE Conte” related to the mobile station UE.
If managing “xt”, the reconnection procedure is successful.

In step S3005, the radio base station eNB # 2 determines that “HO prepar
“source PCI” and “source C-RNTI (Cell-Radio Ne) transferred from the radio base station eNB # 1 in the“ operation process (step S3002) ”
work Temporary Identity) "and" short MAC-I "
And “RRCConnectionReestablish” transmitted by the mobile station UE.
“source PCI” and “source C” included in “hmentRequest”
-RNTI "or" short MAC-I "to compare the" UE C
“texting process (specific process of mobile station UE)” and “verif”
ication processing (authentication processing) ”.

Also, the radio base station eNB # 1 performs “HO preparation process (step S3
002) ”, the security parameters (algorithm, KeNB *, NCC, etc.) are transferred to the radio base station eNB # 2.

Such security parameters are determined after the completion of the reconnection procedure by the mobile station UE and the radio base station eN.
Necessary for continuing security with B # 2.

When the mobile station UE is identified and authenticated, the radio base station eNB # 2 determines in step S3006.
To the mobile station UE, “RRCConnectionReestablish
ment ".

In step S3007, “RRCConnectionRestable” is set.
The communication after “IshmentComplete” is a security process (“cipheri”).
ng "or" integrity protection ").

In step S3006, “RRCConnectionReestablish
shmen "to" SRB1 (Signaling Radio Bearer
1) ”is set, followed by“ RRCReconfigur ”in step S3011.
"SRB2" or "DRB (Dedicated Radio Be
arre) "is re-established, and such communication continues.

In step S3008, “S1 path switch request”
And “S1 path switch response” in step S3009
”Switches the routing in the network.

Here, “matching” of “UE Context” in step S3005
When the processing and the verification process fail, the radio base station eNB # 2
In step S3006, for the mobile station UE, “RRCConnectionRe
Instead of “establishment”, “RRCConnectionReesta”
blushmentReject ".

The mobile station UE performs the “RRCConnectionReestablishment”.
When “Reject” is received, the state transits to the “Idle state”.

3GPP R3-100239 3GPP R3-100240 3GPP R3-100241

As described above, in the LTE scheme, the radio base station eNB # 2 performs “UE” related to the mobile station UE.
When “Context” is not managed, the reconnection procedure of the mobile station UE is to fail.

Therefore, the present invention has been made in view of the above-described problem, and even if the reconnection-destination radio base station does not manage “UE Context” related to the mobile station UE, the reconnection procedure is performed. It is an object of the present invention to provide a mobile communication method, a mobile station, and a radio base station that can succeed in the communication.

A first feature of the present invention is a mobile communication method, in which a mobile station is a first subordinate to a first radio base station.
When detecting a radio link failure in a cell, the process A starts a reconnection procedure for a second radio base station that manages the second cell selected by the cell selection process, and in the reconnection procedure, the mobile station: In the step B of transmitting the CGI of the first cell to the second radio base station and the reconnection procedure, when the second radio base station does not manage the context information of the mobile station, And a step C of acquiring context information of the mobile station from the first radio base station that manages the first cell specified based on CGI.

A second feature of the present invention is a mobile station, which detects a radio link failure in a first cell under the first radio base station, and manages a second radio base that manages a second cell selected by cell selection processing. A control unit configured to start a reconnection procedure for a station, and a transmission configured to transmit the CGI of the first cell to the second radio base station in the reconnection procedure. It is made a summary.

The third feature of the present invention is that, when the mobile station detects a radio link failure in the first cell under the first radio base station, the second radio base station that manages the second cell selected by the cell selection process is provided. When the reconnection procedure is started, the radio base station that operates as the second radio base station, and does not manage the context information of the mobile station in the reconnection procedure,
Reception configured to obtain context information of the mobile station from the first radio base station managing the first cell identified based on the CGI of the first cell transmitted by the mobile station It is a summary to have a part.

As described above, according to the present invention, the connection-destination radio base station performs “U” related to the mobile station UE.
Even when the “E Context” is not managed, it is possible to provide a mobile communication method, a mobile station, and a radio base station that can make the reconnection procedure successful.

1 is an overall configuration diagram of a mobile communication system according to a first embodiment of the present invention. FIG. 3 is a functional block diagram of a mobile station according to the first embodiment of the present invention. FIG. 3 is a functional block diagram of a radio base station according to the first embodiment of the present invention. It is a figure for demonstrating operation | movement of the mobile communication system which concerns on the 1st Embodiment of this invention. It is a figure for demonstrating operation | movement of the mobile communication system which concerns on the 2nd Embodiment of this invention. It is a figure for demonstrating operation | movement of the conventional mobile communication system.

(Mobile communication system according to the first embodiment of the present invention)
A mobile communication system according to a first embodiment of the present invention will be described with reference to FIGS.

The mobile communication system according to the present embodiment is an LTE system (or LTE-Advanced).
d system) mobile communication system, as shown in FIG. 1, the mobility management node MME (Mo
(bicity Management Entity), a radio base station eNB # 1 that manages cell # 1, and a radio base station eNB # 2 that manages cell # 2.

In the present embodiment, the mobile station UE performs RLF in the cell # 1 under the radio base station eNB # 1.
Is detected, the radio base station eNB # that manages the cell # 2 selected by the cell selection process
The case where the reconnection procedure for 2 is started will be described as an example.

As shown in FIG. 2, the mobile station UE according to the present embodiment includes a control unit 11, a transmission unit 12, and a reception unit 13.

When detecting the RLF in the cell # 1 under the control of the radio base station eNB # 1, the control unit 11 performs a cell selection process, and re-registers the radio base station eNB # 2 that manages the cell # 2 selected by the cell selection process. Configured to initiate a connection procedure.

The transmission unit 12 is configured to transmit various signals to the radio base stations eNB # 1 / eNB # 2.

For example, the transmission unit 12 performs the above-described reconnection procedure with respect to the radio base station eNB # 2.
The CGI of cell # 1 is configured to be transmitted.

In addition, the transmission unit 12 performs “RRC Connection Reestablishment”.
“Request” ”may be configured to transmit“ CGI available ”indicating whether or not the CGI of the cell # 1 can be transmitted to the radio base station eNB # 2.

For example, the transmission unit 12 performs “RRC Connection Reestablishment”.
“CGI available” may be transmitted by a 1-bit flag in “t Request”.

The receiving unit 13 is configured to receive various signals from the radio base stations eNB # 1 / eNB # 2.

For example, the receiving unit 13 is configured to receive “CGI request” requesting to transmit the CGI of the cell # 1 from the radio base station eNB # 2.

Specifically, the reception unit 13 receives the “RRCConnectio” from the radio base station eNB # 2.
nReestablishment "may be configured to receive" CGI request ".

In addition, the reception unit 13 includes “RRCConnection” including “CGI request”.
When receiving “nRestablishment”, the transmission unit 12 performs “RRCCon”.
The CGI of the cell # 1 may be transmitted to the radio base station eNB # 2 by “connectionRestablishmentComplete”.

For example, the reception unit 13 reads “RRCConnectionReestablishmen”.
“CGI request” may be received by a 1-bit flag in “t”.

The transmission unit 12 includes “RRCConnectionRees” including the CGI of the cell # 1.
The configuration may be such that security processing is not performed on “tablishmentComplete”.

Here, the transmitter 12 does not include the CGI of the cell # 1 “RRCConnectionR
“establishmentComplete” is configured to perform security processing.

Note that the transmission unit 12 performs the “RRCConnectionReestablishment”.
Request "and DCCH (Dedicated Common Control)
The radio base station eN is transmitted by another message transmitted on the channel / SRB 1).
It may be configured to transmit the CGI of cell # 1 to B # 2.

As illustrated in FIG. 3, the radio base station eNB according to the present embodiment includes a reception unit 21 and a transmission unit 22.
And a context management unit 23.

The context management unit 23 is configured to manage “UE Context” related to each mobile station UE.

Specifically, the context management unit 23 is performed by the surrounding radio base station eNB “
“UE Co” related to the mobile station UE transferred in the “HO Preparation process”
It is configured to manage “ntext”.

The receiving unit 21 is configured to receive various signals from the mobile station UE, and the transmitting unit 22
Is configured to transmit various signals to the mobile station UE.

In this reconnection procedure, when the context management unit 23 of the radio base station eNB # 2 does not manage the “UE Context” related to the mobile station UE, the reception unit 21 of the radio base station eNB # 2 From the radio base station eNB # 1 that manages the cell # 1 that is specified based on the CGI of the cell # 1 transmitted by the “UE Context” related to the mobile station UE
Is configured to get.

In addition, the reception unit 21 of the radio base station eNB # 2 receives “RRCConnec” from the mobile station UE.
"ionReestablishmentRequest" causes "CGI ava
"Cable available" when the "Cable available" is received.
When indicating that the CGI of the cell # 1 can be transmitted, the transmission unit 22 of the radio base station eNB # 2 uses the “RRCConnectionReestablishment”,
Requests the mobile station UE to transmit the CGI of the cell # 1 “CGI request
st ".

Further, the reception unit 21 of the radio base station eNB # 1 receives “X2 R from the radio base station eNB # 2.
When the “LF report” is received, the transmission unit 22 of the radio base station eNB # 1 receives the “X report”.
“Source C-RNTI” and “shor” included in “2 RLF report”
It is determined whether or not “UE Context” that matches “t MAC-I” is managed by the context management unit 23, and only when it is determined that “UE Context” is managed, The “HO preparation process” is performed.

Hereinafter, an example of a specific operation of the mobile communication system according to the present embodiment will be described with reference to FIG.

As illustrated in FIG. 4, the mobile station UE performs radio base station eNB # in step S1001.
When the RLF is detected in the subordinate cell # 1, in step S1002, the radio base station eNB # 2 that manages the cell # 2 selected by the cell selection process is notified of “sour
ce PCI "," source C-RNTI "," short MAC-I "and" CS
"RRCConnectionReestablish" including "G available"
hmentRequest ".

The radio base station eNB # 2 receives the “CSG available” from the cell C1 C
When indicating that the GI can be transmitted, in step S1003, the mobile station UE
In response to this, “RRCConnectionReestablishment” including “CGI request” requesting to transmit CGI of cell # 1 is transmitted.

In step S1004, the mobile station UE transmits the cell # to the radio base station eNB # 2.
“RRCConnectio” containing 1 CGI (ie, “source CGI”)
nReestablishmentComplete "is transmitted.

Here, the mobile station UE uses the conventional “RRCConnectionReestablish”.
Unlike "mentComplete,""RRCConnec" containing the CGI of cell # 1
Security processing (particularly, “ciphering”) is not performed on “tionReestablishmentComplete”.

This is because, at this point, the radio base station eNB # 2 has no security parameters, so that the radio base station eNB # 2 solves the security process (“decip
This is because it is not possible to perform “hering”.

The mobile station UE can determine whether or not to perform security processing based on whether or not “CGI request” is transmitted by a 1-bit flag in “RRCConnectionReestablishment”.

In step S1005, the radio base station eNB # 2 identifies the radio base station eNB # 1 based on the CGI of the cell # 1, and the radio base station eNB # 1 receives “source P
"X2" including "CI", "source C-RNTI", and "short MAC-I"
RLF report "is transmitted.

In step S1006, the radio base station eNB # 1 determines that “UE C
“texting processing” and “verification processing” of “text” are performed.

Here, the radio base station eNB # 1 sets “m” of “UE Context” related to the mobile station UE.
In step S1007, only when the “attaching process” and the “verification process” are successful, that is, when the “UE Context” related to the mobile station UE is managed, the security is established for the radio base station eNB # 2. “X2 HO preparation” including the parameters is transmitted.

In step S1008, the radio base station eNB # 2 transmits “X2 HO preparation ack” to the radio base station eNB # 1.

Here, since the radio base station eNB # 2 was able to obtain the security parameters,
In step S1009, for the mobile station UE, “RRC SecurityMod”
“eCommand” is used to notify the security parameter.

In step S1010, the mobile station UE transmits “RR” to the radio base station eNB # 2.
C SecurityModeComplete "is transmitted.

In step S1011, the radio base station eNB # 2 transmits “S1 path switch request” to the mobility management node MME, and in step S1012.
, The mobility management node MME transmits “S1 path” to the radio base station eNB # 2.
"switch complete" is transmitted.

In step S1013, the radio base station eNB # 2 transmits “X2 UE context release” to the radio base station eNB # 1.

In step S1014, the radio base station eNB # 2 sends an SRB to the mobile station UE.
2 or DRB etc. “RRCConnectionReconfiguration
In step S1015, the mobile station UE transmits “RRCConnectionReconfigurationComplete” to the radio base station eNB # 2.
Send.

As a result, in step S1016, the mobile station UE and the radio base station eNB # 2 (cell #
An RRC connection is established with 2).

In the conventional LTE method, in the reconnection procedure described above, “RRC Secure” is used.
yModeCommand "and" RRC SecurityModeComplete
Is not transmitted / received, but in the mobile history system according to the present embodiment, step S100 is performed.
3 and S1004, since the security processing is not activated, at this timing, “RRC SecurityModeCommand” and “RRC Security”
“ModeComplete” is transmitted and received.

As a result, “RRCConnectionReconfig” in step S1014.
Security processing can be applied to communications after “guration”.

“CGI request” and “source CGI (CGI of cell # 1)”
May be transmitted and received by a dedicated message.

In such a case, the radio base station eNB # 2 sends a CGI of the cell # 1 with a dedicated message.
After acquiring "RRCConnectionReestablishmentCom
The transmission and reception of “plete” and “RRC Connection Reestablishment” may be performed in the same manner as in the case of the conventional LTE system.

In such a case, “RRCConnectionReestablishmentComp
In the transmission / reception of “letter” and “RRCConnectionReestablishment”, the security process can be started.
yModeCommand "and" RRC SecurityModeComplete
"Is no longer necessary.

According to the mobile communication system according to the present embodiment, in the reconnection procedure described above, the radio base station eNB # 2 uses the radio base station eNB based on the CGI of the first cell acquired from the mobile station UE.
Since “UE Context” related to the mobile station UE can be acquired from # 1, even if the “UE Context” related to the mobile station UE is not managed in advance in the radio base station eNB # 2, The reconnection procedure can be successful.

Further, according to the mobile communication system according to the present embodiment, the radio base station eNB # 2 manages the “UE Context” related to the mobile station UE based on the CGI of the first cell. 1 can be specified, so that in the environment where there are many cells using the same PCI (for example, pico cells), the radio base station eNB # 2 previously stores the mobile station U
Even when the “UE Context” related to E is not managed, the reconnection procedure described above can be made successful.

(Modification 1)
Hereinafter, the mobile communication system according to the first modification of the present invention will be described with reference to FIG. 5 while focusing on the differences from the mobile communication system according to the first embodiment described above.

In the mobile communication system according to the first modification of the present invention, it is assumed that there are many cells (for example, pico cells) using the same PCI.

As shown in FIG. 5, the mobile station UE performs radio base station eNB # in step S2001.
When RLF is detected in cell # 1 (pico cell) under one cell, in step S2002, the radio base station eN that manages cell # 2 (macro cell) selected by the cell selection process is detected.
For B # 2, “source PCI”, “source C-RNTI”, and “sh
"RRCConnectionReestablish" including "ort MAC-I"
entRequest ".

In step S2003, the radio base station eNB # 2 determines that “UE C
In the case of not managing “text”, for all the radio base stations eNB in the vicinity,
“X2 RLF report” including “urse PCI”, “source C-RNTI”, and “short MAC-I” is transmitted.

In step S2004, the radio base station eNB that has received the “X2 RLF report” includes “source C-RNTI” included in the “X2 RLF report”.
And “UE Context” related to the mobile station UE based on “short MAC-I”
"Matching process" and "verification process".

Here, each radio base station eNB (for example, radio base station eNB # 1) performs “matching processing” and “verification” of “UE Context” related to the mobile station UE.
Only when “processing” is successful, that is, “X2 RLF report” includes “
“UE Con” that matches “source C-RNTI” and “short MAC-I”
Only when managing “text”, in step S2005, the radio base station eNB
For # 2, "X2 HO preparation" including security parameters
Send.

In step S2006, the radio base station eNB # 2 transmits “X2 HO preparation ack” to the radio base station eNB # 1.

Here, since the radio base station eNB # 2 was able to obtain the security parameters,
In step S2007, for the mobile station UE, “RRC SecurityMod”
“eCommand” is used to notify the security parameter.

In step S2008, the mobile station UE transmits “RR” to the radio base station eNB # 2.
C SecurityModeComplete "is transmitted.

In step S2009, the radio base station eNB # 2 transmits “S1 path switch request” to the mobility management node MME, and in step S2010.
, The mobility management node MME transmits “S1 path” to the radio base station eNB # 2.
"switch complete" is transmitted.

In step S2011, the radio base station eNB # 2 transmits “X2 UE context release” to the radio base station eNB # 1.

In step S2012, the radio base station eNB # 2 sends an SRB to the mobile station UE.
2 or DRB etc. “RRCConnectionReconfiguration
In step S2013, the mobile station UE transmits “RRCConnectionReconfigurationComplete” to the radio base station eNB # 2.
Send.

As a result, in step S2014, the mobile station UE and the radio base station eNB # 2 (cell #
An RRC connection is established with 2).

According to the mobile communication system according to the first modification example, the radio base station eNB # 2 transmits “source PCI” and “source C-RNTI” to all neighboring radio base stations eNB.
”And“ short MAC-I ”and send“ X2 RLF report ”
"Source C-RNTI" and "sho" included in "X2 RLF report"
radio base station eN managing “UE Context” matching “rt MAC-I”
B # 1 transmits to the radio base station eNB # 2 the “UE Context (
Security parameter) "is transmitted, and therefore, in an environment where there are many cells (for example, picocells) using the same PCI, the" UE "related to the mobile station UE in advance in the radio base station eNB # 2 Even if “Context” is not managed, the reconnection procedure described above can be successful.

  The characteristics of the present embodiment described above may be expressed as follows.

The first feature of the present embodiment is a mobile communication method, in which the mobile station UE is a radio base station eNB.
RLF (radio link failure) in cell # 1 (first cell) under # 1 (first radio base station)
, The process A for starting the reconnection procedure for the radio base station eNB # 2 (second radio base station) that manages the cell # 2 (second cell) selected by the cell selection process, and the reconnection procedure In step B in which the mobile station UE transmits the CGI of the cell # 1 to the radio base station eNB # 2, and in the reconnection procedure, the radio base station eNB # 2 When the “Context (context information)” is not managed, the CGI
From the radio base station eNB # 1 that manages the cell # 1 specified based on the mobile station UE
And a step C of acquiring “UE Context” according to the above.

In the first feature of the present embodiment, in the process B, the mobile station UE performs “RRCConnect”.
"ionReestablishmentRequest (reconnection request signal)"
Step B1 of transmitting “CGI available (transmission availability information)” indicating whether or not CGI of cell # 1 can be transmitted to the radio base station eNB # 2, and the radio base station eNB # 2 When the received “CGI available” indicates that the CGI of the cell # 1 can be transmitted, “RRCConnectionReestablishes”
The mobile station UE transmits a “CGI request (request information)” requesting the mobile station UE to transmit the CGI of the cell # 1 by “hment (reconnection signal)”, and the mobile station UE performs “CGI request”. "RRCConnectionReee" in response to "request"
Step B3 of transmitting CGI of cell # 1 to radio base station eNB # 2 by “stabilization Complete (reconnection completion signal)”.

In the first feature of the present embodiment, in step B3, the mobile station UE determines that “RRCCon
It is not necessary to perform security processing for “connectionReestablishmentComplete”.

The second feature of the present embodiment is the mobile station UE, which is a cell # under the radio base station eNB # 1.
1, the control unit 11 configured to start a reconnection procedure for the radio base station eNB # 2 that manages the cell # 2 selected by the cell selection process when detecting the RLF;
The gist of the present invention is that the reconnection procedure includes a transmission unit 12 configured to transmit the CGI of the cell # 1 to the radio base station eNB # 2.

In the second feature of the present embodiment, the transmission unit 12 performs “RRCConnectionRe
When “CGI available” is transmitted to the radio base station eNB # 2 by “establishmentRequest”, and the transmission unit 12 receives “CGI request” from the radio base station eNB # 2. , "RRCC
It may be configured to transmit the CGI of the cell # 1 to the radio base station eNB # 2 by “connection Restoration Complete”.

In the second feature of the present embodiment, the transmission unit 12 performs “RRCConnectionRe
It may be configured not to perform security processing for “establishmentComplete”.

A third feature of the present embodiment is that, when the mobile station UE detects RLF in the cell # 1 under the radio base station eNB # 1, the radio base station eNB # that manages the cell # 2 selected by the cell selection process 2, the radio base station eNB that operates as the radio base station eNB # 2, and in the reconnection procedure, the “UE C
When not managing “text”, the CGI of the cell # 1 transmitted by the mobile station UE
The gist of the present invention is to include a receiving unit 21 configured to acquire a “UE Context” related to the mobile station UE from the radio base station eNB # 1 that manages the cell # 1 that is identified based on the above.

In the third feature of the present embodiment, the radio base station eNB has received the “CGI available” when the receiving unit 21 receives “CGI available” from the mobile station UE by “RRCConnectionReestablishmentRequest”.
If “available” indicates that the CGI of cell # 1 can be transmitted, “
A transmission unit 22 configured to transmit “CGI request” requesting the mobile station UE to transmit CGI of the cell # 1 may be provided by “RRCConnectionReestablishment”.

Note that the operations of the mobile station UE and the radio base stations eNB # 1 / eNB # 2 described above may be implemented by hardware, may be implemented by a software module executed by a processor, or a combination of both May be implemented.

Software modules include RAM (Random Access Memory), flash memory, ROM (Read Only Memory), EPROM (
Erasable Programmable ROM) and EEPROM (Elect.
(Regularly Erasable and Programmable ROM)
Alternatively, it may be provided in a storage medium of an arbitrary format such as a register, a hard disk, a removable disk, or a CD-ROM.

Such a storage medium is connected to the processor so that the processor can read and write information from and to the storage medium. Further, such a storage medium may be integrated in the processor. Such a storage medium and processor may be provided in the ASIC. Such an ASIC may be provided in the mobile station UE and the radio base stations eNB # 1 / eNB # 2. Further, the storage medium and the processor may be provided in the mobile station UE and the radio base stations eNB # 1 / eNB # 2 as discrete components.

As described above, the present invention has been described in detail using the above-described embodiment.
Obviously, the invention is not limited to the embodiments described herein. The present invention can be implemented as modified and changed modes without departing from the spirit and scope of the present invention defined by the description of the scope of claims. Therefore, the description of the present specification is for illustrative purposes and does not have any limiting meaning to the present invention.

UE ... mobile station eNB # 1, eNB # 2 ... radio base station 11 ... control unit 12, 22 ... transmission unit 13, 21 ... reception unit 23 ... context management unit

Claims (8)

When the mobile station detects a radio link failure in the first cell under the first radio base station, the process A starts a reconnection procedure for the second radio base station that manages the second cell selected by the cell selection process; ,
In the reconnection procedure, the mobile station transmits a CGI of the first cell to the second radio base station B.
In the reconnection procedure, when the second radio base station does not manage the context information of the mobile station, from the first radio base station that manages the first cell specified based on the CGI, And C for acquiring context information of the mobile station. Step B is
Step B1 in which the mobile station transmits transmission availability information indicating whether or not the CGI of the first cell can be transmitted to the second radio base station by a reconnection request signal.
When,
When the second radio base station indicates that the received transmission permission information can transmit the CGI of the first cell, the reconnection signal indicates the CGI of the first cell to the mobile station. A process B2 for transmitting request information for requesting transmission;
The mobile station has a step B3 of transmitting the CGI of the first cell to the second radio base station by a reconnection completion signal according to the request information. The mobile communication method described in 1. The mobile communication method according to claim 2, wherein in the step B3, the mobile station does not perform security processing on the reconnection completion signal. Control configured to start a reconnection procedure for a second radio base station that manages a second cell selected by cell selection processing when a radio link failure is detected in a first cell under the first radio base station And
A mobile station, comprising: a transmission unit configured to transmit the CGI of the first cell to the second radio base station in the reconnection procedure. The transmission unit is configured to transmit transmission availability information indicating whether or not the CGI of the first cell can be transmitted to the second radio base station by a reconnection request signal. ,
When the reconnection signal including request information for requesting to transmit the CGI of the first cell is received from the second radio base station, the transmission unit uses the second radio base station to transmit the second radio The mobile station according to claim 4, wherein the mobile station is configured to transmit the CGI of the first cell to a base station. The mobile station according to claim 5, wherein the transmission unit is configured not to perform security processing on the reconnection completion signal. When the mobile station detects a radio link failure in the first cell under the first radio base station, the mobile station starts a reconnection procedure for the second radio base station that manages the second cell selected by the cell selection process. A radio base station operating as the second radio base station,
In the reconnection procedure, when context information of the mobile station is not managed, the first radio base that manages the first cell specified based on the CGI of the first cell transmitted by the mobile station A radio base station comprising a receiving unit configured to acquire context information of a mobile station from a station. The reception unit receives the transmission permission / inhibition information when the reception unit receives transmission permission / inhibition information indicating whether or not the CGI of the first cell can be transmitted by a reconnection request signal from the mobile station. Indicates that the mobile station can transmit the CGI of the first cell by means of a reconnection signal when the mobile station indicates that the CGI of the first cell can be transmitted. The radio base station according to claim 7, further comprising a configured transmission unit.

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