JP5123742B2 - Handover method, mobile station and radio base station - Google Patents

Description

  The present invention relates to a handover method in which a mobile station performs handover from a first cell to a second cell, a mobile station, and a radio base station.

  With reference to FIG. 7, an operation of a mobile station UE performing handover from a “first cell (Source cell)” to a “second cell (Target cell)” in a conventional LTE (Long Term Evolution) system will be described. To do.

  As illustrated in FIG. 7, in step S2001, the mobile station UE transmits “RRC Measurement Report” to the first cell (Source cell).

  Here, “RRC Measurement Report” includes a measurement result of radio quality in a cell (for example, the second cell) specified by “PCI (Physical Cell ID)”. Specifically, “PCI” is a spreading code used in such a cell.

  In step S2002, the first cell determines to perform handover of the mobile station UE to the second cell (Target cell) specified by “PCI” included in the received “RRC Measurement Report”, and “HO Preparation” is transmitted to the cell.

  In step S2003, the second cell transmits “HO Preparation Ack” including “new C-RNTI”, which is information for identifying the mobile station UE in the second cell, to the first cell. “HO Preparation Ack” may include designation information of “individual preamble”.

  In step S2004, the first cell transmits “RRC Reconfiguration (HO Command)” including “new C-RNTI” to the mobile station UE.

  When “individual preamble” is designated in step S2003, “individual preamble” designation information is also included in “RRC Reconfiguration (HO Command)” in step S2004.

  In step S2005, the mobile station UE moves to the second cell indicated by “RRC Reconfiguration (HO Command)”, and establishes downlink synchronization for the second cell.

  In step S2006, “RA Preamble” that is an individual preamble or a common (random) preamble is transmitted to the second cell via RACH (Random Access Channel).

  The mobile station UE uses “individual preamble” when “individual preamble” is designated in step S2004, and uses a common preamble when “individual preamble” is not designated.

  Also, the mobile station UE uses the common preamble when the expiration date of the “individual preamble” has expired.

  In step S2007, the second cell transmits “RA Response” to the mobile station UE. By “RA Response”, an uplink resource to be used in the next step 2008 is allocated.

  In step S2008, the mobile station UE transmits “RRC Reconfiguration Complete (HO Command Complete)” to the second cell using the uplink resource allocated by “RA Response”.

  In step S2009, the second cell transmits “Path Switch” to the exchange MME.

  In step S2010, the second cell transmits “Release Resource” to the first cell.

  Here, when the second cell detects the data addressed to the mobile station UE or the occurrence of data from the mobile station UE, the “PDCCH (Physical Downlink Control Channel)” using “new C-RNTI” is used. Then, scheduling information is transmitted to the mobile station UE.

  In step S2011, the second cell transmits data (U-Plane Data) addressed to the mobile station UE to the mobile station UE using a downlink resource (PDSCH: Physical Downlink Shared Channel) allocated by the scheduling information. To do.

  Alternatively, in step 2011, the mobile station UE uses the uplink resource (PUSCH: Physical UpShared Channel) allocated by the scheduling information in the second cell, to the second cell, the data addressed to the second cell ( U-Plane Data) is transmitted.

  Here, in the conventional LTE mobile communication system, when the mobile station UE uses the “dedicated preamble”, the mobile station UE receives the “RA Response” from the second cell, and then receives the “RA Response” from the first cell to the second cell. It is configured to determine that the handover to is successful.

  This is because the “individual preamble” is reserved in advance for the handover access of the mobile station UE in the second cell, and the second cell receives the “individual preamble” so that the arrival of the mobile station UE Since the mobile station UE receives the “RA Response” for the “individual preamble” from the second cell, it can be considered that the second cell has received the “individual preamble”. It is.

  In the conventional LTE mobile communication system, when the mobile station UE uses the “common preamble”, the mobile station UE receives the schedule information from the first cell via the “PDCCH” by the second cell. It is configured to determine that the handover to the second cell is successful.

  This is because the “common preamble” is selected and transmitted at random by a plurality of different mobile stations UE at the same time, and when the mobile station UE receives “RA Response” or “RRC Reconfiguration Complete (HO Command)”. This is because there is a possibility that a contention has occurred at the time of receiving “HARQ Ack” for “Complete”.

  Therefore, after receiving “HARQ Ack” for “RRC Reconfiguration Complete (HO Command Complete)”, the mobile station UE is addressed to “new C-RNTI” that is an ID in its second cell via “PDCCH”. Only when the scheduling information is received, it can be considered that the access to the second cell is successful.

  In the LTE scheme, there are 64 types of RA preambles, which can be divided into those reserved as individual preambles for each cell and those used as common preambles.

For example, RA preambles # 0 to # 47 can be classified as common preambles, and RA preambles # 48 to # 63 can be classified into individual preambles. Such division may be different for each cell.
3GPP TS36.300 V8.4.0, March 2008 3GPP TS36.331 V8.1.0, March 2008

  However, in the conventional LTE mobile communication system, “PCI”, which is identification information for identifying each cell, is configured to be repeatedly assigned to a plurality of non-adjacent cells. As shown in FIG. 8, the cell assumed by the mobile station UE as a “second cell (Target cell)” and the “first cell (Source cell)” are assumed to be a “second cell (Target cell)”. There may be cases where the cell is different.

  As described above, in the conventional LTE mobile communication system, when the mobile station UE receives predetermined information via the “RA Response” or “PDCCH”, the mobile station UE considers that the handover has succeeded. In a case where the cell assumed by the station UE as the “second cell (Target cell)” is different from the cell assumed by the “first cell (Source cell)” as the “second cell (Target cell)”. Even so, there is a problem that the mobile station UE determines that the handover from the first cell to the second cell is successful.

  This is a case where the mobile station UE uses the “individual preamble” and the second cell happens to assign the same “individual preamble” to another mobile station UE. This is because such an “individual preamble” may be detected and “RA Response” may be returned.

  In addition, when the mobile station UE uses the “individual preamble” and the “individual preamble” is classified as the “common preamble” in the second cell, the second cell is required. This is because it is assumed that “common preamble” has been received, and “RA Response” may be returned.

  In addition, there is another mobile station UE that uses the same “C-RNTI” as the “new C-RNTI” in the second cell when the mobile station UE uses the “common preamble”. This is because the mobile station UE may erroneously receive scheduling information transmitted via the “PDCCH” addressed to another mobile station UE by the second cell.

  If the mobile station UE performs handover to the second cell that is not intended by the first cell and determines that the handover is successful, the mobile station UE is located in the wrong second cell and cannot detect an error. There was a problem.

  In particular, in the second cell that is not intended by the mobile station UE, there is already another mobile station UE that uses the same “C-RNTI” as the “new C-RNTI” assigned to the mobile station UE. In this case, the mobile station UE that has been erroneously handed over, such as scheduling information transmitted to another mobile station UE via “PDCCH”, scheduling information transmitted to itself via “PDCCH”, etc. In some cases, data may be received using downlink resources allocated by the “PDCCH”, or data may be transmitted using uplink resources allocated by the “PDCCH”. It was.

  In addition, when the mobile station UE transmits “HARQ Ack” or uplink data for downlink data, there is a problem in that communication of other mobile stations UE is hindered.

  Such a problem is likely to be manifested particularly when a large number of small base stations such as femto base stations, home base stations, and “CSG (closed subscriber cells)” are installed.

  In addition, such a problem may become apparent when a self-setting function or self-optimizing function is introduced in which each cell autonomously selects and sets "PCI (Physical Cell ID)". There is sex.

  Therefore, the present invention has been made in view of the above-described problems. The mobile station UE assumes that the mobile station UE assumes a “second cell (Target cell)” and the “first cell ( It is detected whether or not the handover from the first cell to the second cell has succeeded by detecting that the source cell is different from the cell assumed as the “target cell”. It is an object of the present invention to provide a handover method, a mobile station, and a radio base station that can be quickly determined.

  According to a first aspect of the present invention, there is provided a handover method in which a mobile station performs handover from a first cell to a second cell, wherein the first cell is connected to the mobile station in the mobile communication network. A step of notifying a handover instruction message including a first cell identifier capable of uniquely specifying two cells and instructing to perform the handover; and after the mobile station receives the handover instruction message, In contrast, a step of notifying a handover completion message, a step of receiving broadcast information in the second cell after the mobile station notifies the handover completion message, and the mobile station included in the handover instruction message Whether the first cell identifier and the second cell identifier included in the broadcast information match. And summarized in that a step of.

  In the first aspect of the present invention, the mobile station may include a step of performing reconnection when it is determined that the first cell identifier and the second cell identifier do not match.

  In the first aspect of the present invention, when the mobile station cannot determine that the first cell identifier and the second cell identifier match within a predetermined period after receiving the handover instruction message, You may have the process of connecting.

  A second feature of the present invention is a mobile station configured to perform a handover from a first cell to a second cell, the handover instruction instructing to perform the handover transmitted by the first cell A first acquisition unit configured to acquire from a message a first cell identifier capable of uniquely identifying the second cell in a mobile communication network; and after receiving the handover instruction message, the second cell A notification unit configured to notify a handover completion message, and a notification information reception unit configured to receive broadcast information in the second cell after the handover completion message is notified And the first cell identifier included in the handover instruction message and the second cell identifier included in the broadcast information. And gist by comprising a determination unit configured to determine whether or not a child is matched.

  In the second aspect of the present invention, a reconnection unit configured to perform reconnection may be provided when it is determined that the first cell identifier and the second cell identifier do not match.

  In the second aspect of the present invention, reconnection is performed when it is not determined that the first cell identifier and the second cell identifier match within a predetermined period after receiving the handover instruction message. You may comprise the reconnection part comprised.

  A third feature of the present invention is a radio base station that manages the first cell in a mobile communication system in which the mobile station is configured to perform handover from the first cell to the second cell, A handover preparation message instructing the second cell to prepare for the handover is transmitted, and a handover preparation response message that is a response to the handover preparation message is received from the second cell. A first cell identifier that uniquely identifies the second cell within the mobile communication network to the mobile station when the handover preparation response message is received, and A radio interface configured to notify a handover instruction message instructing to perform And it is required to include a and vinegar.

  As described above, according to the present invention, the cell assumed by the mobile station UE as the “second cell (Target cell)” and the “first cell (Source cell)” are the “second cell (Target cell)”. ) ", Even if it is different from the assumed cell, detect this fact and determine whether or not the handover from the first cell to the second cell has succeeded. A handover method, a mobile station, and a radio base station can be provided.

(Configuration of mobile communication system according to the first embodiment of the present invention)
The configuration of the mobile communication system according to the first embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, in the mobile communication system according to the present embodiment, the mobile station UE performs a handover from a “first cell (Serving cell)” to a “second cell (Target cell)”. It is configured. In the mobile communication system according to the present embodiment, cells managed by a plurality of radio base stations eNB are formed.

  Here, as shown in FIG. 2, in the mobile communication system according to the present embodiment, the mobile station UE and the radio base station eNB are respectively a physical (PHY) layer, a MAC layer, an RLC layer, a PDCP layer, and an RRC layer. A protocol stack consisting of

  As illustrated in FIG. 3, the radio base station eNB that manages the second cell includes a radio interface 11, an X2 interface 12, and a neighboring base station information management unit 13.

  The X2 interface 12 serves as an interface with the peripheral radio base station eB.

  Specifically, the X2 interface 12 transmits “HO Preparation (handover preparation message)” instructing the second cell to prepare for handover, and “HO Preparation (handover preparation)” is transmitted from the second cell. “HO Preparation Ack (handover preparation response message)” that is a response to “message)”.

  The peripheral base station information management unit 13 is configured to manage peripheral base station information related to radio base stations around the radio base station eNB.

  Specifically, the neighboring base station information management unit 13 is configured to store “X2 interface”, “PCI”, and “GCI” in association with each other as the neighboring base station information.

  Here, the “X2 interface” includes information (for example, TE-ID) for specifying cells under the control of the radio base station around the radio base station eNB, and “PCI” is the radio base station eNB's. “GCI” includes “PCI” of the surrounding radio base station (cell), and “GCI” is a “Global Cell ID (first cell identifier) that can uniquely identify the radio base station (cell) around the radio base station eNB. )"including.

  For example, “GCI” may be an ID that can uniquely identify a radio base station (cell) around the radio base station eNB in the PLMN, or a tracking area (TA: Tracking) to which the radio base station eNB belongs. It may be an ID that can uniquely identify a radio base station (cell) within (Area).

  Note that “GCI” as the “first cell identifier that can uniquely identify a radio base station (cell) around the radio base station eNB within the mobile communication network” is referred to as “BCI: Broadcast Cell ID”. May be.

  Note that, for example, “PCI” is a scramble code that is repeatedly used in 504 cells, and radio base stations around the radio base station eNB cannot be uniquely identified in the network.

  The peripheral base station information management unit 13 may be configured not to store “GCI” as the peripheral base station information, that is, to store only “X2 interface” and “PCI” in association with each other. .

  The radio interface 11 serves as an interface with the mobile station UE in a subordinate cell (first cell).

  Specifically, when the “HO Preparation Ack (handover preparation response message)” is received from the second cell that is the handover destination candidate cell, the radio interface 11 is set to the mobile station UE in the subordinate cell. , “GCI (first cell identifier)”, and is configured to notify “HO Command (handover instruction message)” instructing handover from the first cell to the second cell.

  Here, the radio interface 11 notifies “HO Command (handover instruction message)” including “GCI” associated with “X2 interface” or “PCI” which is information for specifying the second cell. The “HO Command (handover instruction message)” including “GCI” included in the “HO Preparation Ack (handover preparation response message)” received from the second cell may be notified. It may be configured as follows.

  The radio interface 11 may be configured to transmit only the lower bits of “GCI” in order to reduce the overhead of the “HO Command (handover instruction message)”.

  As illustrated in FIG. 4, the mobile station UE includes a handover processing unit 21, a broadcast information receiving unit 22, a determination unit 23, and a reconnection unit 24.

  The handover processing unit 21 is configured to transmit and receive signals (RRC protocol messages) related to the handover process between the handover source cell (first cell) and the handover destination candidate cell (second cell). .

  For example, the handover processing unit 21 acquires “GCI (first cell identifier)” that can uniquely identify the second cell in the mobile communication network from the “HO Command (handover instruction message)” transmitted by the first cell. Is configured to do.

  In addition, the handover processing unit 21 is configured to notify the second cell of the “HO Complete (handover completion message)” after the “HO Command (handover instruction message)” is received.

  The broadcast information receiving unit 22 is configured to receive broadcast information in the second cell after the handover processing unit 21 is notified of “HO Complete (handover completion message)”.

  Specifically, the broadcast information receiving unit 22 receives “SIB1 (System Information Block 1)” that is periodically broadcast and acquires “GCI (second cell identifier)” included in the SIB1. Is configured to do.

  The determination unit 23 includes “GCI (first cell identifier)” included in “HO Command (handover instruction message)” and “GCI (second cell identifier)” included in broadcast information (SIB1). Are configured to determine whether or not they match.

  The reconnection unit 24 is configured to perform reconnection when it is determined that “GCI (first cell identifier)” and “GCI (second cell identifier)” do not match.

  For example, the reconnection unit 24 receives a “HO Command (handover instruction message)” within a predetermined period, that is, until a predetermined timer that is started upon reception of the “HO Command (handover instruction message)” expires. In addition, when it cannot be determined that “GCI (first cell identifier)” matches “GCI (second cell identifier)”, reconnection is performed.

For example, in such a case, the reconnection unit 24 is configured to perform a reconnection procedure by selecting a cell and transmitting a “RRC Connection Recovery Request (reconnection request message)” to the selected cell. ing.
(Operation of the mobile communication system according to the first embodiment of the present invention)
With reference to FIG.5 and FIG.6, operation | movement of the mobile communication system which concerns on the 1st Embodiment of this invention is demonstrated.

  Specifically, with reference to FIG. 5, in a conventional LTE (Long Term Evolution) mobile communication system, the mobile station UE moves from a “first cell (serving cell, source cell)” to a “second cell (target cell)”. cell) ”will be described.

  As shown in FIG. 5, in step S1001, the mobile station UE performs “RRC Measurement Report (measurement report)” for reporting the measurement result of the radio quality in the neighboring cell to the first cell (Source cell). Send.

  Here, the mobile station UE transmits “RRC Measurement Report (measurement report)” including the radio quality measurement result in a cell that satisfies a predetermined condition defined by “Measurement Configuration” among the observable neighboring cells. .

  In the “RRC Measurement Report (measurement report)”, each cell is specified by “PCI”. Also, “RRC Measurement Report (measurement report)” does not include “GCI” of each cell.

  Also, since “PCI” is a spreading code, the mobile station UE can easily detect “PCI” by cell search. On the other hand, since “GCI” is included in the broadcast information (SIB1), the mobile station UE needs to read the broadcast information (SIB1) in order to detect “GCI”. , “GCI” cannot be detected more easily than “PCI”.

  In particular, when the broadcast information is for cells of different carriers, it is difficult to detect “GCI”, for example, “Measurement Gap” is required.

  In step S1002, the first cell transmits “HO Preparation” to the second cell (Target cell) specified by “PCI” included in the received “RRC Measurement Report”.

  In step S1003, the second cell transmits “HO Preparation Ack” including “new C-RNTI”, which is information for identifying the mobile station UE in the second cell, to the first cell. “HO Preparation Ack” may include designation information of “individual preamble”.

  In step S1004, the first cell transmits “RRC Reconfiguration (HO Command, handover instruction message)” including “new C-RNTI” to the mobile station UE.

  Here, “RRC Reconfiguration (HO Command, handover instruction message)” further includes “PCI” and “GCI (first cell identifier)” of the second cell.

  When “GCI” is included in “HO Preparation Ack”, the first cell transmits “RRC Reconfiguration (HO Command, handover instruction message)” including “GCI”.

  On the other hand, when “GCI” is not included in “HO Preparation Ack”, the first cell extracts “GCI” corresponding to the second cell, and performs “RRC Reconfiguration (HO Command, Handover instruction message) ". If “individual preamble” is designated in step S1003, “individual preamble” designation information is also included in “RRC Reconfiguration (HO Command, handover instruction message)” in step S1004.

  Here, the mobile station UE transmits “HARQ Ack” for notifying the reception processing of “RRC Reconfiguration (HO Command)” in the MAC layer (layer 2) to the first cell.

  In step S1005, the mobile station UE moves to the second cell indicated by “RRC Reconfiguration (HO Command)” and establishes downlink synchronization for the second cell.

  In step S1006, “RA Preamble” which is an individual preamble or a common (random) preamble is transmitted to the second cell via the RACH.

  The mobile station UE uses “individual preamble” when “individual preamble” is designated in step S1004, and uses “common preamble” when “individual preamble” is not designated.

  Also, the mobile station UE uses the “common preamble” when the expiration date of the “individual preamble” has expired.

  In step S1007, the second cell transmits “RA Response” to the mobile station UE. By “RA Response”, an uplink resource to be used in the next step 1008 is allocated.

  In Step S1008, the mobile station UE transmits “RRC Reconfiguration Complete (HO Complete, handover complete message)” to the second cell using the uplink resource allocated by “RA Response”.

  Here, the second cell transmits “HARQ Ack” for notifying the mobile station UE that the reception process of “RRC Reconfiguration Complete (HO Command Complete)” in the MAC layer (layer 2) is successful. To do.

  In Step S1009, the second cell transmits “Path Switch” to the exchange MME.

  In step S1010, the second cell broadcasts broadcast information (SIB1) including “GCI (second cell identifier)” of the second cell.

  In step S1011, the second cell transmits “Release Resource” to the first cell.

  In step S1012, the mobile station UE uses the “GCI (first cell identifier)” included in the “HO Command (handover instruction message)” received in step S1004 and the broadcast information (SIB1) received in step S1010. It is determined whether or not the included “GCI (second cell identifier)” matches.

  If it is determined that both match, the mobile station UE determines that the handover process has been successful.

  Here, when the second cell detects the data addressed to the mobile station UE or the occurrence of data from the mobile station UE, the “PDCCH (Physical Downlink Control Channel)” using “new C-RNTI” is used. Then, scheduling information is transmitted to the mobile station UE.

  In step S1013, the second cell transmits data (U-Plane Data) addressed to the mobile station UE to the mobile station UE using a downlink resource (PDSCH: Physical Downlink Shared Channel) allocated by the scheduling information. To do.

  Alternatively, in step 1013, the mobile station UE uses the uplink resource (PUSCH: Physical UpShared Channel) allocated by the scheduling information to the second cell to the data addressed to the second cell (PUSCH). U-Plane Data) is transmitted.

  Next, referring to FIG. 6, in a conventional LTE (Long Term Evolution) mobile communication system, a mobile station UE moves from a “first cell (serving cell, source cell)” to a “second cell (target cell)”. The operation for performing handover (failure example) will be described.

  As illustrated in FIG. 6, in step S1001A, the mobile station UE transmits “RRC Measurement Report (measurement report)” for reporting a measurement result of radio quality in the neighboring cells to the first cell.

  Here, the mobile station UE transmits “RRC Measurement Report (measurement report)” including “PCI” identifying “cell # 2” to the first cell.

  In step S1002A, it is assumed that the first cell is identified by “cell # 1” assumed as “second cell”, that is, “PCI” included in “RRC Measurement Report (measurement report)”. “HO Preparation” is transmitted to “Cell # 1”.

  That is, “PCI” in which the mobile station UE specifies “cell # 2” and “PCI” in which the first cell specifies “cell # 1” are the same.

  In step S1003A, “cell # 1” transmits “HO Preparation Ack” including “new C-RNTI” that is information for identifying the mobile station UE in “cell # 1” to the first cell. . “HO Preparation Ack” may include designation information of “individual preamble”.

  In step S1004A, the first cell transmits “RRC Reconfiguration (HO Command, handover instruction message)” including “new C-RNTI” to the mobile station UE.

  Here, “RRC Reconfiguration (HO Command, handover instruction message)” further includes “PCI” and “GCI (cell identifier)” of “cell # 1”.

  If “individual preamble” is designated in step S1003A, “individual preamble” designation information is also included in “RRC Reconfiguration (HO Command, handover instruction message)” in step S1004A.

  Here, the mobile station UE transmits “HARQ Ack” for notifying the reception processing of “RRC Reconfiguration (HO Command)” in the MAC layer (layer 2) to the first cell.

  In step S1005A, the mobile station UE corresponds to “PCI” included in “RRC Reconfiguration (HO Command)”, and the mobile station UE assumes “cell # 2” assumed as the “second cell”. Then, downlink synchronization is established for “cell # 2.”

  In step S1006A, “RA Preamble” that is an individual preamble or a common (random) preamble is transmitted to “cell # 2” via RACH.

  The mobile station UE uses “individual preamble” when “individual preamble” is designated in step S1004, and uses “common preamble” when “individual preamble” is not designated.

  Also, the mobile station UE uses the “common preamble” when the expiration date of the “individual preamble” has expired.

  In Step S1007A, “Cell # 2” transmits “RA Response” to the mobile station UE. By “RA Response”, an uplink resource to be used in the next step 1008A is allocated.

  In step S1008A, the mobile station UE transmits “RRC Reconfiguration Complete (HO Complete, handover complete message)” to “cell # 2” using the uplink resource allocated by “RA Response”.

  In step S1010A, the mobile station UE receives broadcast information (SIB1) including “GCI (second cell identifier)” of “cell # 2” broadcast by “cell # 2”.

  In step S1012A, the mobile station UE adds the “GCI (first cell identifier)” included in the “HO Command (handover instruction message)” received in step S1004A and the broadcast information (SIB1) received in step S1010A. It is determined whether or not the included “GCI (second cell identifier)” matches.

  In this case, since “GCI (first cell identifier)” identifies “cell # 1” and “GCI (second cell identifier)” identifies “cell # 2,” both It does not match. Therefore, the mobile station UE determines that the handover process has failed.

  As a result, in step 1012B, the mobile station UE performs cell selection processing based on the reception quality of neighboring cells and the like, and in step 1012C, performs a reconnection procedure for the selected cell.

(Operations and effects of the mobile communication system according to the first embodiment of the present invention)
According to the mobile communication system according to the first embodiment of the present invention, the mobile station UE transmits “GCI (first cell identifier)” included in the “HO Command (handover instruction message)” and broadcast information ( It is determined whether or not “GCI (second cell identifier)” included in SIB1) matches, and if both match, it is determined that the handover from the first cell to the second cell has succeeded. Since the mobile station UE is configured as described above, the mobile station UE assumes that the mobile station UE is assumed to be a “second cell (Target cell)” and the “first cell (Source cell)” is a “second cell ( It is possible to accurately detect whether or not the handover from the first cell to the second cell has succeeded by detecting that the cell is different from the cell assuming “Target cell” ”. it can.

(Example of change)
The operations of the mobile station UE and the radio base station eNB described above may be implemented by hardware, may be implemented by a software module executed by a processor, or may be implemented by a combination of both. .

  The software module includes a RAM (Random Access Memory), a flash memory, a ROM (Read Only Memory), an EPROM (Erasable Programmable ROM), an EEPROM (Electronically Erasable and Programmable ROM, a hard disk, a registerable ROM, a hard disk). Alternatively, it may be provided in a storage medium of an arbitrary format such as 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 or the radio base station eNB. Further, the storage medium and the processor may be provided as a discrete component in the mobile station UE or the radio base station eNB.

  Although the present invention has been described in detail using the above-described embodiments, it is obvious to those skilled in the art that the present invention is not limited to the embodiments described in this specification. 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.

1 is an overall configuration diagram of a mobile communication system according to a first embodiment of the present invention. FIG. 3 is a protocol stack diagram in the mobile communication system 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. FIG. 3 is a functional block diagram of a mobile station according to the first embodiment of the present invention. It is a sequence diagram which shows operation | movement (success) of the mobile communication system which concerns on the 1st Embodiment of this invention. It is a sequence diagram which shows operation | movement (failure) of the mobile communication system which concerns on the 1st Embodiment of this invention. It is a sequence diagram which shows operation | movement of the conventional mobile communication system. It is a figure for demonstrating operation | movement of the conventional mobile communication system.

Explanation of symbols

eNB ... radio base station 11 ... radio interface 12 ... X2 interface 13 ... neighboring base station information management unit UE ... mobile station 21 ... handover processing unit 22 ... broadcast information receiving unit 23 ... determination unit 23 ... reconnection unit

Claims (6)

A handover method in which a mobile station performs handover from a first cell to a second cell,
The first cell notifying the mobile station of a handover instruction message including a first cell identifier capable of uniquely identifying the second cell in a mobile communication network and instructing the mobile station to perform the handover; ,
The mobile station notifying the second cell of a handover completion message after receiving the handover instruction message;
Receiving notification information in the second cell after the mobile station notifies the handover completion message;
The mobile station includes a step of determining whether or not the first cell identifier included in the handover instruction message matches a second cell identifier included in the broadcast information. A handover method.   2. The handover method according to claim 1, further comprising a step of performing reconnection when the mobile station determines that the first cell identifier and the second cell identifier do not match.   The mobile station has a step of performing reconnection when it cannot be determined that the first cell identifier and the second cell identifier match within a predetermined period of time after receiving the handover instruction message. The handover method according to claim 1. A mobile station configured to perform a handover from a first cell to a second cell,
A first cell identifier that can uniquely identify the second cell in a mobile communication network is obtained from a handover instruction message that instructs to perform the handover transmitted by the first cell. An acquisition unit;
A notification unit configured to notify a handover completion message to the second cell after the handover instruction message is received;
A broadcast information receiving unit configured to receive broadcast information in the second cell after the handover completion message is notified;
A determination unit configured to determine whether or not the first cell identifier included in the handover instruction message matches the second cell identifier included in the broadcast information; A mobile station characterized by that.   The mobile station according to claim 4, further comprising a reconnection unit configured to perform reconnection when it is determined that the first cell identifier and the second cell identifier do not match. .   A reconnection unit configured to perform reconnection when it cannot be determined that the first cell identifier and the second cell identifier match within a predetermined period of time after receiving the handover instruction message; The mobile station according to claim 4, wherein:

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