JP2018033001A - Wireless base station and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to appropriately reflect a change to a wireless base station in a neighbor relationship, when cell information of the wireless base station is changed, even if X2 interface is not established.SOLUTION: The wireless base station includes: a base station identifying unit for identifying a wireless base station on which X2 interface is not established and whose handover has failed in a preparation phase among wireless base stations in neighbor relationship with the wireless base station; and an invalidation unit for invalidating a neighbor relationship with the wireless base station identified by the base station identifying unit.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a radio base station and a program.

A technique is known in which, when information of a wireless base station such as PCI (Physical Cell ID) is changed, the change contents are notified to a wireless base station in a neighbor relationship by communication between base stations using the X2 interface. (For example, see Patent Document 1).
[Prior art documents]
[Patent Literature]
[Patent Document 1] Japanese Patent Application Laid-Open No. 2011-176471

  Even when the X2 interface is not established, when the cell information of the radio base station is changed, it is desirable that the change be appropriately reflected in the radio base stations in a neighbor relationship.

  According to a first aspect of the present invention, a radio base station is provided. The radio base station may include a base station identifying unit that identifies a radio base station in which the X2 interface has not been established and the handover has failed in the preparation phase among the radio base stations in a neighbor relationship with the radio base station. . The radio base station may include an invalidation unit that invalidates a neighbor relationship with the radio base station identified by the base station identification unit.

  The base station specifying unit is a radio base station in which the X2 interface is not established among the radio base stations in a neighbor relationship with the radio base station, and handover has failed continuously for a predetermined number of times in the preparation phase. May be specified.

  According to a second aspect of the present invention, a radio base station is provided. The radio base station may include a base station identifying unit that identifies, among radio base stations in a neighbor relationship with the radio base station, a radio base station in which handover has failed continuously for a predetermined number of times. The radio base station may include an invalidation unit that invalidates a neighbor relationship with the radio base station identified by the base station identification unit.

  The base station identification unit may identify a radio base station in which handover processing has failed continuously for a predetermined number of times in a preparation phase among radio base stations in a neighbor relationship with the radio base station.

  The radio base station may further include a neighbor cell information storage unit that stores neighbor cell information that is cell information of a radio base station that is in a neighbor relationship with the radio base station, and the invalidation unit is configured to identify the base station The neighbor cell information of the radio base station specified by the unit may be deleted. The neighbor cell information may include a radio base station name, and the radio base station receives a handover request including a handover destination radio base station name from a mobile station establishing a radio communication connection; and When the neighbor cell information including the radio base station name included in the handover request is not stored in the neighbor cell information storage unit, the radio base station name is obtained by transmitting the radio base station name to the core network. And a neighbor cell information receiving unit that receives the neighbor cell information from the core network, and the neighbor cell information storage unit may store the neighbor cell information received by the information receiving unit. The neighbor cell information may include PCI (Physical Cell ID), TAC (Tracking Area Code), EARFCN (E-UTRAN Absolute Radio Channel Number), and ECGI (E-UTRAN Cell ID).

  According to the 3rd aspect of this invention, the program for functioning a computer as said radio | wireless base station is provided.

  It should be noted that the above summary of the invention does not enumerate all the necessary features of the present invention. In addition, a sub-combination of these feature groups can also be an invention.

An example of the radio base station 100 is shown schematically. An example of the neighbor cell list 500 is shown schematically. An example of a functional structure of the radio base station 100 is shown schematically. An example of the flow of processing by the radio base station 100 is schematically shown. 1 schematically shows an example of a computer 900 that functions as a radio base station 100.

  Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

  FIG. 1 schematically shows an example of a radio base station 100. The radio base station 100 is a radio base station that supports, for example, LTE (Long Term Evolution) radio communication. The mobile station 400 is, for example, a mobile phone such as a smartphone and a tablet terminal.

  The radio base station 100 forms a radio communication area 102. The radio communication area 102 overlaps with the radio communication area 202 formed by the radio base station 200 and the radio communication area 302 formed by the radio base station 300. The radio base station 100 is in a neighbor relationship with the radio base station 200 and the radio base station 300.

  The radio base station 100 stores neighbor cell information which is cell information of a radio base station having a neighbor relationship. The neighbor cell information may include PCI (Physical Cell ID). The neighbor cell information may include TAC (Tracking Area Code). The neighbor cell information may include EARFCN (E-UTRAN Absolute Radio Frequency Channel Number). The neighbor cell information may include ECGI (E-UTRAN Cell Global ID).

  In the example illustrated in FIG. 1, the radio base station 100 stores the neighbor cell information of the radio base station 200 and the neighbor cell information of the radio base station 300. The radio base station 100 has established the X2 interface 10 with the radio base station 200. The radio base station 100 has not established the X2 interface 10 with the radio base station 300.

  When the radio base station 100 establishes a neighbor relationship with another radio base station, if the X2 interface 10 is not established with the other radio base station, processing for establishing the X2 interface 10 is executed. However, there is an upper limit to the number of X2 interfaces 10 that the radio base station 100 can establish. This is because if the number of X2 interfaces 10 is large, the processing load on the radio base station 100 increases. Therefore, when the upper limit is reached, the X2 interface 10 is not newly established. Particularly in the city center and the like, since there are a large number of radio base stations around one radio base station, there are relatively many cases where the number of X2 interfaces 10 reaches the upper limit.

  When the cell information of the radio base station 200 is changed, the radio base station 200 notifies the radio base station 100 of the changed content via the X2 interface 10. Therefore, the cell information of the radio base station 200 and the neighbor cell information of the radio base station 200 stored in the radio base station 100 are kept in agreement.

  When the cell information of the radio base station 300 is changed, since the X2 interface 10 is not established between the radio base station 100 and the radio base station 300, the change content is not notified to the radio base station 100. Therefore, in this case, the cell information of the radio base station 300 and the neighbor cell information of the radio base station 300 stored in the radio base station 100 do not match. This will continue until the neighbor cell information is changed. When the cell information of the radio base station 300 and the neighbor cell information of the radio base station 300 stored in the radio base station 100 do not match, handover from the radio base station 100 to the radio base station 300 fails 100%. .

  Therefore, the radio base station 100 according to the present embodiment identifies a radio base station in which the X2 interface 10 has not been established and the handover has failed in the preparation phase among the radio base stations in a neighbor relationship. Then, the neighbor relationship with the specified radio base station is invalidated. For example, the radio base station 100 invalidates the neighbor relationship with the radio base station by deleting the neighbor cell information of the identified radio base station.

  When the neighbor cell information of the specified radio base station is deleted, when the radio base station 100 subsequently receives a handover request for the specified radio base station from the mobile station 400, the ANR (Automatic Neighbor Relation) of the radio base station 100 By functioning, the latest cell information of the specified radio base station is registered in the radio base station 100. Thereby, the cell information of the specified radio base station and the neighbor cell information of the radio base station stored in the radio base station 100 can be matched.

  By specifying the radio base station on the condition that the X2 interface is not established, when the cell information of the radio base station for which the X2 interface is established, that is, the radio base station is changed, the contents of the change are wireless. It can be prevented that the neighbor relationship with the radio base station notified to the base station 100 is unnecessarily invalidated.

  By specifying the radio base station on the condition that the handover has failed in the preparation phase, it is possible to identify the radio base station when the handover fails for reasons other than the mismatch between the cell information and the neighbor cell information. Can be reduced. This is because if the cell information and the neighbor cell information do not match, the handover always fails in the preparation phase. For example, if handover fails in the execution phase (Execution Phase), the preparation phase has succeeded, so the cell information and the neighbor cell information match, and the failure has occurred due to a radio environment problem or the like. become. Therefore, specifying a radio base station on the condition that handover failed in the preparation phase may unnecessarily invalidate the neighbor relationship even though the cell information and the neighbor cell information match. Can be reduced.

  The radio base station 100 may further specify the radio base station on the condition that the handover has failed continuously for a predetermined number of times in the preparation phase. When the handover fails in the preparation phase, the cause may be other than the mismatch between the cell information and the neighbor cell information. However, the cause of 100% failure is most likely the mismatch between the cell information and the neighbor cell information. If the handover fails once in the preparation phase, the cause may be other than the mismatch between the cell information and the neighbor cell information, but if the handover fails continuously in the preparation phase, the cell information and the neighbor cell information It is very likely that this is caused by a mismatch. Therefore, by specifying a radio base station on the condition that handover has failed continuously for a predetermined number of times in the preparation phase, when handover fails due to reasons other than mismatch between cell information and neighbor cell information, It is possible to reduce the possibility that the neighbor relationship is unnecessarily invalidated even though the cell information and the neighbor cell information match.

  FIG. 2 schematically shows an example of a neighbor cell list 500. The neighbor cell list 500 includes neighbor cell information of a plurality of radio base stations that are in a neighbor relationship with the radio base station 100. The neighbor cell list 500 includes a PCI column 502, a TAC column 504, an EARFCN column 506, an ECGI column 508, and an X2 column 510. In the X2 column 510, the presence or absence of the X2 interface is registered. The neighbor cell list 500 may further include other information such as a frequency value used by the radio base station.

  2 exemplifies a case where the neighbor cell information of the radio base station 200 and the neighbor cell information of the radio base station 300 are registered in the neighbor cell list 500. Here, for example, when the TAC of the radio base station 200 is changed, the radio base station 100 receives the change content from the radio base station 200 and reflects the change content in the neighbor cell list 500.

  On the other hand, for example, when the TAC of the radio base station 300 is changed, the radio base station 100 and the radio base station 300 have not established the X2 interface 10, so the change content is not notified to the radio base station 300 and the radio base station 300 The cell information of the base station 300 and the neighbor cell information of the radio base station 300 stored in the radio base station 100 do not match. In this case, when the radio base station 100 receives a handover request to the radio base station 300 from the mobile station 400, the handover fails in the preparation phase.

  Here, according to the radio base station 100 according to the present embodiment, when the handover to the radio base station 300 that has not established the X2 interface has failed in the preparation phase, the neighbor cell information of the radio base station 300 is changed. It is deleted from the neighbor cell list 500. Thereby, when the radio base station 100 subsequently receives a handover request to the radio base station 300 from the mobile station 400, the ANR functions and the latest cell information of the radio base station 300 is registered in the neighbor cell list 500. Will be.

  FIG. 3 schematically illustrates an example of a functional configuration of the radio base station 100. The radio base station 100 includes a neighbor cell information storage unit 110, a communication control unit 112, a handover request reception unit 114, a handover process execution unit 116, a neighbor cell information reception unit 118, a base station identification unit 120, and an invalidation unit 122. .

  The neighbor cell information storage unit 110 stores neighbor cell information of a radio base station that has a neighbor relationship with the radio base station 100. The neighbor cell information storage unit 110 may store a plurality of neighbor cell information as the neighbor cell list 500. The neighbor cell information storage unit 110 may store a plurality of pieces of neighbor cell information in a format other than the neighbor cell list 500.

  The communication control unit 112 controls communication with the mobile station 400. The communication control unit 112 may establish a wireless communication connection with the mobile station 400. The communication control unit 112 may relay communication of the mobile station 400 that has established a wireless communication connection.

  The handover request receiving unit 114 receives a handover request from the mobile station 400 that has established a wireless communication connection. The handover request receiving unit 114 may receive a handover request including a handover destination radio base station name. The radio base station name is, for example, ECGI.

  The handover process execution unit 116 executes a process for handing over the mobile station 400 to another radio base station. The handover process executing unit 116 may execute S1 handover when handing over the mobile station 400 to the radio base station 300 that has not established the X2 interface 10.

  The S1 handover includes a preparation phase, an execution phase, and a completion phase (Completion Phase). The handover process executing unit 116 may start the preparation phase in response to the handover request receiving unit 114 receiving a handover request from the mobile station 400. Further, the handover process execution unit 116 starts the preparation phase in response to the communication control unit 112 determining the handover destination radio base station of the mobile station 400 based on the MR (Measurement Report) received from the mobile station 400. You can do it.

  When the handover request receiving unit 114 receives a handover request from the mobile station 400, the handover process executing unit 116 determines whether or not the neighbor cell information corresponding to the ECGI included in the handover request is stored in the neighbor cell information storage unit 110. Confirm. If stored, the handover process execution unit 116 continues the process. If not stored, the handover process execution unit 116 requests cell information corresponding to ECGI from the core network. The neighbor cell information reception unit 118 receives cell information transmitted from the core network side in response to a request from the handover process execution unit 116. The neighbor cell information storage unit 110 stores the cell information received by the neighbor cell information reception unit 118 as neighbor cell information.

  The base station specifying unit 120 specifies a radio base station that meets a condition from radio base stations that are in a neighbor relationship with the radio base station 100. The condition is at least one of the fact that the X2 interface with the radio base station 100 has not been established, the handover from the radio base station 100 has failed in the preparation phase, and the handover has failed continuously for a predetermined number of times. May be included.

  For example, the base station specifying unit 120 specifies a radio base station in which the X2 interface has not been established and handover has failed in the preparation phase among the radio base stations in a neighbor relationship with the radio base station 100. Further, for example, the base station specifying unit 120, among the radio base stations that are in a neighbor relationship with the radio base station 100, has not established the X2 interface, and the handover has failed continuously for a predetermined number of times in the preparation phase. Identify the radio base station.

  Further, for example, the base station specifying unit 120 specifies a radio base station in which handover has failed continuously for a predetermined number of times from among the radio base stations in a neighbor relationship with the radio base station 100. As a result, it is possible to identify a radio base station that has a high possibility that the neighbor cell information stored in the neighbor cell information storage unit 110 and the cell information do not match. Further, for example, the base station specifying unit 120 specifies a radio base station in which handover has failed consecutively for a predetermined number of times in the preparation phase among the radio base stations in a neighbor relationship with the radio base station 100. As a result, it is possible to identify a radio base station that has a higher possibility that the neighbor cell information stored in the neighbor cell information storage unit 110 and the cell information do not match.

  The invalidating unit 122 invalidates the neighbor relationship with the radio base station specified by the base station specifying unit 120. The invalidation unit 122 may invalidate the neighbor relationship with the radio base station by deleting the neighbor cell information stored in the neighbor cell information storage unit 110 of the specified radio base station.

  FIG. 4 schematically shows an example of the flow of processing by the radio base station 100. FIG. 4 illustrates a processing flow when a handover request is received from the mobile station 400. Each process illustrated in FIG. 4 is executed mainly by a control unit included in the radio base station 100.

  In step 402 (step may be abbreviated as S), the handover request receiving unit 114 receives a handover request including the name of the handover destination radio base station from the mobile station 400. In S404, it is determined whether or not the neighbor cell information corresponding to the radio base station name included in the handover request is stored in the neighbor cell information storage unit 110. If it is determined that it is stored, the process proceeds to S406, and if it is determined that it is not stored, the process proceeds to S408. In S406, by executing ANR, the neighbor cell information receiving unit 118 receives cell information corresponding to the radio base station name included in the handover request from the core network, and stores it in the neighbor cell information storage unit 110. .

  In S408, the handover process execution unit 116 executes a process of handing over the mobile station 400 to the handover destination radio base station included in the handover request in accordance with the handover request received in S402. In S410, it is determined whether an X2 interface has been established with the handover destination radio base station. If it is established, the process proceeds to S426, and if it is not established, the process proceeds to S412.

  In S412, it is determined whether the handover has failed. If the handover has not failed, the process proceeds to S416. If the handover has failed, the process proceeds to S414. In S414, it is determined whether or not the handover has failed in the preparation phase. If it has not failed in the preparation phase, the process proceeds to S416, and if it has failed in the preparation phase, the process proceeds to S420.

  In S416, it is determined whether or not the number of times handover to the handover destination radio base station included in the handover request has failed in the preparation phase is zero. If it is determined that the number of times is not zero, the process proceeds to S418. If it is determined that the number is not zero, the process proceeds to S426. In S418, the number of failures is reset. The number of failures may be reset every time a predetermined time elapses.

  In S420, it is determined whether or not the number of times handover to the handover destination radio base station included in the handover request has failed continuously in the preparation phase is greater than a threshold value. If it is determined that there are not, the process proceeds to S422, and if it is determined that there are not, the process proceeds to S424.

  In S422, 1 is added to the number of failures. In S424, the invalidating unit 122 invalidates the neighbor relationship with the handover destination radio base station.

  In S426, it is determined whether an end instruction has been received. If an end instruction has not been received, the process returns to S402 and waits for a handover request. If it is determined that an end instruction has been received, the process ends.

  FIG. 5 schematically shows an example of a computer 900 that functions as the radio base station 100. The computer 900 includes a control unit 902, a storage unit 904, a wired communication unit 906, and a wireless communication unit 908.

  The control unit 902 includes a processor and performs various controls. The storage unit 904 includes a RAM, a ROM, a hard disk, and the like, and stores various types of information. The wired communication unit 906 has a wired communication interface and executes communication with a core network or the like. The wireless communication unit 908 has an antenna and performs wireless communication with the mobile station 400.

  A program that is installed in the computer 900 and causes the computer 900 to function as the radio base station 100 may work on a processor or the like of the control unit 902 to cause the computer 900 to function as each unit of the radio base station 100. The information processing described in these programs is read by the computer 900, whereby the neighbor cell information storage unit 110, which is a specific means in which the software and the various hardware resources described above cooperate, the communication control unit 112, a handover request receiving unit 114, a handover process executing unit 116, a neighbor cell information receiving unit 118, a base station specifying unit 120, and an invalidating unit 122. And the specific radio base station 100 according to the use purpose is constructed | assembled by implement | achieving the calculation or processing of the information according to the use purpose of the computer 900 in this embodiment by these specific means. Note that the program according to the present embodiment is installed in the computer 900 including the neighbor cell information storage unit 110, the communication control unit 112, the handover request reception unit 114, the handover process execution unit 116, and the neighbor cell information reception unit 118. Thus, the computer 900 may function as the base station identification unit 120 and the invalidation unit 122.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  The order of execution of each process such as operations, procedures, steps, and stages in the apparatus, system, program, and method shown in the claims, the description, and the drawings is particularly “before” or “prior to”. It should be noted that it can be realized in any order unless the output of the previous process is used in the subsequent process. Regarding the operation flow in the claims, the description, and the drawings, even if it is described using “first,” “next,” etc. for convenience, it means that it is essential to carry out in this order. It is not a thing.

10 X2 interface, 100 radio base station, 102 radio communication area, 110 neighbor cell information storage unit, 112 communication control unit, 114 handover request reception unit, 116 handover process execution unit, 118 neighbor cell information reception unit, 120 base station identification unit , 122 invalidation unit, 200 wireless base station, 202 wireless communication area, 300 wireless base station, 302 wireless communication area, 400 mobile station, 500 neighbor cell list, 502 PCI column, 504 TAC column, 506 EARFCN column, 508 ECGI column , 510 X2 column, 900 computer, 902 control unit, 904 storage unit, 906 wired communication unit, 908 wireless communication unit

Claims (8)

A wireless base station,
Among the radio base stations that are in a neighbor relationship with the radio base station, a base station identification unit that identifies a radio base station for which X2 interface has not been established and handover has failed in the preparation phase;
A radio base station comprising: an invalidation unit that invalidates a neighbor relationship with the radio base station identified by the base station identification unit.   The base station specifying unit is a radio base station in which the X2 interface is not established among the radio base stations in a neighbor relationship with the radio base station, and handover has failed continuously for a predetermined number of times in the preparation phase The radio base station according to claim 1, wherein the radio base station is specified. A wireless base station,
Among the radio base stations in a neighbor relationship with the radio base station, a base station identifying unit that identifies a radio base station in which handover has failed continuously a predetermined number of times,
A radio base station comprising: an invalidation unit that invalidates a neighbor relationship with the radio base station identified by the base station identification unit.   The base station identification unit identifies a radio base station in which handover processing has failed continuously for a predetermined number of times in a preparation phase among radio base stations in a neighbor relationship with the radio base station. The radio base station described. A neighbor cell information storage unit that stores neighbor cell information that is cell information of a radio base station that is in a neighbor relationship with the radio base station;
5. The radio base station according to claim 1, wherein the invalidation unit deletes the neighbor cell information of the radio base station identified by the base station identification unit. The neighbor cell information includes a radio base station name,
The radio base station is
A request receiving unit that receives a handover request including a name of a wireless base station that is a handover destination from a mobile station that has established a wireless communication connection;
When the neighbor cell information including the radio base station name included in the handover request is not stored in the neighbor cell information storage unit, the radio base station name is obtained by transmitting the radio base station name to the core network. A neighbor cell information receiving unit that receives neighbor cell information from the core network,
The radio base station according to claim 5, wherein the neighbor cell information storage unit stores the neighbor cell information received by the information reception unit.   The neighbor cell information includes PCI (Physical Cell ID), TAC (Tracking Area Code), EARFCN (E-UTRAN Absolute Radio Channel Number), and ECGI (E-UTRAN Cell Global ID). The radio base station described in 1.   The program for functioning a computer as a wireless base station as described in any one of Claim 1 to 7.

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