JP2013162275A - Base station, communication system, and communication method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an eNB which can change the kind of services offered by a HeNB to which a UE may connect.SOLUTION: An eNB 100a transmits a first directive for detecting a HeNB to a UE 300a on the basis of information that congestion in cells provided by the eNB 100a has been detected. The eNB 100a receives the result of detection from the UE 300a for the first directive transmitted. If, when the HeNB 200 was detected by the UE 300a, the HeNB 200a is limiting access by the UE 300a, the eNB 100a transmits a second directive for requesting the removal of access limits by the HeNB 200a to the HeNB 200a via an MME/S-GW 400. On the basis of the second directive transmitted, the eNB 100a has the UE 300a handed over from the eNB 100a to the HeNB 200a by using the MME/S-GW 400.

Description

  The present invention relates to a base station that communicates with a mobile station, a communication system including the base station, a communication method in the base station, and a program for controlling the base station.

  Currently, 3GPP (3rd Generation Partnership Project) is studying specifications for LTE-A (Long Term Evolution-Advance). In LTE-A, cells of various types are arranged in a mixed state.

  Examples of the cell types include a macro cell provided by an eNB (evolved Node B: base station), a micro cell, a pico cell, and a femto cell provided by a HeNB (Home evolved Node B: indoor base station). Patent Document 1).

  Further, the HeNB has three types of access modes (Access Modes), which are provided as service types to be provided: an open mode, a closed mode, and a hybrid mode. In other words, the cells provided by the HeNB include an open cell corresponding to the open mode, a CSG (Closed Subscriber Group) cell corresponding to the closed mode, and a hybrid cell corresponding to the hybrid mode (see Non-Patent Document 2).

  Further, as a method for increasing service capacity in an environment in which macro cells and micro cells are mixed, for example, a method disclosed in Patent Document 1 is known. In this method, when an MME (Mobility Management Entity) detects congestion of an eNB, the service types of all HeNBs existing in the service area (in the cell) of the eNB can be changed. Thereby, the overload state in the said eNB is eliminated.

JP 2011-4399 A

3GPP TS 22.220 V11.3.0 (2011-09) (3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; Service requirements for Home Node B (HNB) and Home eNode B (HeNB) (Release 11)) 3GPP TS 36.331 V10.3.0 (2011-09) (3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Resource Control (RRC); Protocol specification (Release 10))

  However, in the method of Patent Literature 1, all HeNB service types existing in the eNB service area are uniformly switched. Therefore, even if the HeNB has no possibility of connection because there is no UE in the vicinity, the service type is changed.

  Since the HeNB is a personal small base station, the cost required for the operation of the HeNB is borne by the owner of the HeNB. Therefore, changing the service type uniformly has a problem.

  The present invention has been made in view of the above-described problems, and the purpose thereof is an eNB capable of changing a service type of a HeNB to which a UE may connect, a communication system including the eNB, a communication method in the eNB, And providing a program for controlling the eNB. Another object is to provide an eNB capable of improving the connectivity of a UE to a base station (eNB, HeNB), a communication system including the eNB, a communication method in the eNB, and a program for controlling the eNB. It is to provide. Still another object is to provide a HeNB capable of improving communication quality between the UE and the HeNB, a communication system including the HeNB, a communication method in the HeNB, and a program for controlling the HeNB. .

  In accordance with certain aspects of the present invention, the base station communicates with the mobile station and the mobility management entity. The base station uses the first command to detect a neighboring base station that constitutes a second cell that is narrower than the first cell, based on detection of congestion in the first cell constituted by the base station. A first transmission means for transmitting to the mobile station, a reception means for receiving a detection result from the mobile station based on transmission of the first command, and a neighboring base station, When the neighboring base station restricts the access of the mobile station, a second command for requesting the removal of the access restriction in the detected neighboring base station is sent via the mobility management entity to the neighboring base station. Hand over the mobile station to the neighboring base station detected from the base station constituting the first cell using the mobility management entity based on the second transmission means for transmitting to the mobile station and the second command transmitted Handover control means.

  Preferably, the first command notifies the base stations constituting the first cell that the detected neighboring base station has been detected even when access by the mobile station is restricted. Including instructions to

Preferably, the base station further includes detection means for detecting congestion.
Preferably, when a plurality of neighboring base stations are detected, when each of the plurality of neighboring base stations restricts the access of the mobile station, the second transmitting means sends a second command to the detected plurality of To the neighboring base stations. The handover control means selects one neighboring base station from the detected plurality of neighboring base stations, and hands over the mobile station from the base station constituting the first cell to the selected neighboring base station.

  Preferably, the second transmission means transmits a third command for instructing access restriction to the neighboring base stations not selected via the mobility management entity.

  Preferably, the second command is a command for the detected neighboring base station to change the second cell formed by the neighboring base station from the closed subscriber group cell to the hybrid cell or the open cell.

  Preferably, the first cell is a macro cell. The second cell is a microcell, picocell, or femtocell.

  According to another aspect of the present invention, the base station communicates with the mobile station and the mobility management entity to configure the first cell. Based on the fact that the mobility management entity has received the earthquake early warning, the base station moves a plurality of base stations each constituting a second cell that is narrower than the first cell managed by the mobility management entity Receiving means for receiving a notification indicating that the access restriction of the station has been released via the mobility management entity, and a plurality of cells constituting the second cell for the mobile station based on the reception of the notification Transmitting means for transmitting a command for detecting neighboring base stations installed in the vicinity of the mobile station among the base stations, and receiving means for receiving the detection result from the mobile station based on the transmission of the command, Handover control means for handing over the mobile station to the detected base station from the base station constituting the first cell using the mobility management entity based on the detection of the peripheral base station.

  Preferably, the transmission means further transmits to the mobile station information representing the base station whose access restriction has been removed based on the notification being received.

  Preferably, the notification is a notification indicating that access restriction has been released for a base station installed in the first cell among a plurality of base stations constituting the second cell.

  Preferably, the notification is a notification indicating that the second cell is changed from a closed subscriber group cell to a hybrid cell or an open cell.

  Preferably, the first cell is a macro cell. The second cell is a microcell, picocell, or femtocell.

  According to still another aspect of the present invention, the base station communicates with a plurality of mobile stations and a mobility management entity, and can individually restrict access to each of the plurality of mobile stations. The base station detects that congestion has been detected in the first cell constituted by the base station in the state where access restriction is not performed, or a decrease in service quality of a mobile station that is not subject to access restriction. Based on that, a transmitting means for transmitting to the mobile station subject to access restriction a command for detecting a neighboring base station of the mobile station constituting a second cell different from the first cell; Based on the transmission of the command, the receiving means for receiving the detection result from the mobile station subject to the access restriction, and the mobility management entity is used based on the fact that the mobile station subject to the access restriction detects the neighboring base station. Then, the handover control means for handing over the mobile station to the neighboring base station detected from the base station, and based on the handover, the status of the base station is accessed. And a switching means for switching the state of performing the access restriction to the mobile station to be accessed limit from a state in which limit is not performed.

  Preferably, the base station transmits a command as to whether or not the state of the base station can be changed from a state in which access restriction is not performed to a state in which access restriction is performed on a mobile station subject to access restriction. It is further provided with a determination means for determining before performing.

  Preferably, the mobile terminal further includes an acquisition unit that acquires a communication status around the base station using the mobility management entity. The determination means determines whether or not the change is possible based on the acquired communication status.

  Preferably, the base station further includes measurement means for measuring the strength of radio waves received from the neighboring base stations of the base station. The determination means determines whether or not the change is possible based on the measured intensity.

  Preferably, the second cell is a macro cell. The first cell is a microcell, picocell, or femtocell.

  According to still another aspect of the present invention, a communication system includes a mobile station, a first base station that constitutes a first cell, and a second base that constitutes a second cell that is narrower than the first cell. And a mobility management entity that manages the first base station and the second base station. The first base station uses the first command for detecting the second base station to the mobile station based on the detection of congestion in the first cell configured by the first base station. Includes first transmission means for transmitting. The mobile station detects the second base station based on the reception of the first command from the first base station, and the second transmission means transmits the detection result to the first base station. Including. The first base station is a second receiving means for receiving the detection result from the mobile station, and the second base station detects the second base station, and the second base station restricts access to the mobile station. A second command for requesting release of access restriction in the detected second base station is transmitted to the second base station via the mobility management entity. Transmission means. Based on the reception of the second instruction, the second base station informs the first base station via the mobility management entity that a release means for releasing the access restriction and that the access restriction has been released. Notification means for notifying. The first base station further includes handover control means for handing over the mobile station to the second base station detected from the first base station using the mobility management entity based on the reception of the notification.

  According to still another aspect of the present invention, a communication system includes a plurality of mobile stations, a first base station that constitutes a first cell, and a second cell that is narrower than the first cell. A second base station; and a mobility management entity that manages the first base station and the second base station. The mobility management entity includes a receiving means for receiving the earthquake early warning, and a plurality of second base stations, when each of the second base stations restricts access to the mobile station, First transmission means for transmitting, to the second base station, a first command for requesting cancellation of the access restriction of the mobile station in each of the second base stations. Based on the reception of the first command, the second base station, via the mobility management entity, a release means for releasing the access restriction of the mobile station, and a notification indicating that the access restriction has been released, Second transmitting means for transmitting to the first base station. The first base station detects, based on the reception of the notification, the mobile station from among the plurality of second base stations, a second base station installed around the mobile station. And third transmitting means for transmitting the command. The mobile station includes detection means for detecting a neighboring base station based on the reception of the second command, and fourth transmission means for transmitting the detection result to the first base station. The first base station further includes handover control means for handing over the mobile station to the peripheral base station detected from the first base station using the mobility management entity based on the detection of the peripheral base station. .

  According to still another aspect of the present invention, a communication system includes a plurality of mobile stations, a first base station that constitutes a first cell, a second base station that constitutes a second cell, And a mobility management entity for managing the second base station and the second base station. The first base station is a base station that can individually restrict access to each of a plurality of mobile stations. The first base station is based on the fact that congestion is detected in the first cell configured by the first base station or a decrease in service quality of a mobile station not subject to access restriction is detected. First transmission means for transmitting a command for detecting a second base station to a mobile station subject to access restriction is included. The mobile station subject to the access restriction receives a command from the first base station, detects a second base station, and transmits a detection result to the first base station. Transmission means. The first base station has detected the mobile station from the first base station using the mobility management entity based on the fact that the mobile station subject to access restriction has detected the second base station. A handover control means for performing handover to the second base station, and based on the handover, the state of the first base station is accessed from a state where access restriction is not performed to a mobile station subject to access restriction. Switching means for switching to a state in which the restriction is performed.

  According to yet another aspect of the invention, the communication method is used in a base station that communicates with a mobile station and a mobility management entity. A communication method includes: a first command for detecting a neighboring base station that configures a second cell that is narrower than the first cell, based on detection of congestion in the first cell configured by the base station; Are transmitted to the mobile station, the step of receiving the detection result from the mobile station based on the transmission of the first command, and the peripheral base station is detected, the peripheral base station Transmitting a second command for requesting release of access restriction in the detected neighboring base station to the neighboring base station via the mobility management entity when the access of the mobile station is restricted; And handing over the mobile station to the neighboring base station detected from the base station constituting the first cell using the mobility management entity based on the transmission of the second command.

  According to still another aspect of the present invention, the communication method is used in a base station that communicates with a mobile station and a mobility management entity and constitutes a first cell. The communication method is based on the fact that the mobility management entity has received the earthquake early warning, and a plurality of base stations each configuring a second cell that is narrower than the first cell managed by the mobility management entity moves. Receiving a notification indicating that the access restriction of the station has been removed via the mobility management entity, and, based on the reception of the notification, a plurality of messages constituting the second cell for the mobile station A step of transmitting a command for detecting a neighboring base station installed around the mobile station among the base stations, a receiving means for receiving a detection result from the mobile station based on the transmission of the command, and a neighboring base And handing over the mobile station to the neighboring base station detected from the base station constituting the first cell using the mobility management entity based on the detected station.

  According to still another aspect of the present invention, the communication method is used in a base station that communicates with a plurality of mobile stations and a mobility management entity and can individually restrict access to each of the plurality of mobile stations. In the communication method, congestion is detected in the first cell configured by the base station in a state where access restriction is not performed, or a decrease in service quality of a mobile station that is not subject to access restriction is detected. And a step of transmitting a command for detecting a base station in the vicinity of the mobile station constituting the second cell different from the first cell to the mobile station subject to access restriction, Based on the transmission, the step of receiving the detection result from the mobile station subject to access restriction, and based on the fact that the mobile station subject to access restriction detected the neighboring base station, using the mobility management entity, Handover of the mobile station from the base station to the neighboring base station detected, and based on the handover, the state of the base station is subjected to access restriction. It is provided with a step of switching the state of performing the access restriction from the state not to the mobile station to be accessed restrictions.

  According to yet another aspect of the invention, a program is used to control a base station that communicates with a mobile station and a mobility management entity. The program issues a first command for detecting a neighboring base station that constitutes a second cell that is narrower than the first cell, based on detection of congestion in the first cell constituted by the base station. A step of transmitting to the mobile station, a step of receiving a detection result from the mobile station based on the transmission of the first command, and a case where a neighboring base station is detected, the neighboring base station moving Transmitting the second command for requesting the removal of the access restriction in the detected neighboring base station to the neighboring base station via the mobility management entity when the access of the station is restricted; Based on the transmission of the second command, using the mobility management entity, handing over the mobile station to the neighboring base station detected from the base station constituting the first cell, and executing to the processor of the base station Let .

  According to yet another aspect of the present invention, the program is used to communicate with a mobile station and a mobility management entity and to control a base station that constitutes the first cell. The program is based on the fact that the mobility management entity has received the earthquake early warning, and a plurality of base stations each configuring a second cell that is narrower than the first cell managed by the mobility management entity are mobile stations. Receiving a notification indicating that the access restriction has been removed via the mobility management entity, and a plurality of bases constituting the second cell for the mobile station based on the reception of the notification Transmitting a command for detecting a neighboring base station installed around the mobile station among the stations, receiving means for receiving a detection result from the mobile station based on the command transmission, and a neighboring base station The base station processor executes the step of handing over the mobile station to the detected base station from the base station constituting the first cell using the mobility management entity based on the detected base station

  According to still another aspect of the present invention, a program is used to control a base station that communicates with a plurality of mobile stations and a mobility management entity and can individually restrict access to each of the plurality of mobile stations. It is done. The program detects that congestion has been detected in the first cell configured by the base station in the state where access restriction is not performed, or a decrease in service quality of a mobile station that is not subject to access restriction. A command for detecting a base station in the vicinity of the mobile station constituting the second cell different from the first cell, to the mobile station subject to access restriction, Based on the transmission, the step of receiving the detection result from the mobile station subject to the access restriction, and the mobile station subject to the access restriction detecting the neighboring base station, the mobility management entity is used to Handover of the mobile station from the base station to the neighboring base station detected, and based on the handover, the access restriction is performed on the state of the base station. And a step of switching the state of performing the access restriction from the state where no cracking to the mobile station to be accessed restrictions, to be executed by the processor of the base station.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the base station (eNB) which can change the service classification of the small base station (HeNB) with which UE may connect. Moreover, according to this invention, it becomes possible to improve the connectivity to UE's base station (eNB, HeNB). Moreover, according to this invention, it becomes possible to improve the communication quality between UE and HeNB.

1 is a schematic configuration diagram of a communication system according to a first embodiment. It is a figure for demonstrating the process when eNB detects congestion in the cell which self comprises. It is a sequence chart for demonstrating the process of a communication system. It is a flowchart showing the flow of the process in eNB. It is a figure showing the typical hardware constitutions of eNB. It is a figure showing the hardware constitutions of UE. It is the figure which showed the hardware constitutions of MME / S-GW. It is a sequence chart for demonstrating the other process in a communication system. 10 is a sequence chart for explaining processing of the communication system in the second embodiment. It is a figure for demonstrating the process when eNB detects congestion in the cell which HeNB comprises. 10 is a sequence chart for explaining processing of the communication system in the third embodiment.

  The communication system according to each embodiment of the present invention will be described below with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

[Embodiment 1]
<A. System configuration>
FIG. 1 is a schematic configuration diagram of a communication system 1 according to the present embodiment. Referring to FIG. 1, a communication system 1 includes a plurality of eNBs (evolved Node B: base stations) 100a, 100b, a plurality of HeNBs (Home evolved Node B: indoor base stations) 200a, 200b, 200c, and a UE ( User equipment (mobile stations) 300a and 300b, MME / S-GW (Mobility Management Entity / Serving Gateway) 400, HeNB-GW (Home evolved Node B-Gateway) : Indoor base station gateway) 500. Note that the number of eNBs, UEs, and HeNBs constituting the communication system 1 is an example, and is not limited to the above.

  eNB100a, 100b and HeNB200a are connected so that communication with MME / S-GW400 is possible. The HeNB 200b and 200c are communicably connected to the MME / S-GW 400 via the HeNB-GW 500. Specifically, the HeNBs 200a, 200b, and 200c are communicably connected to the MME / S-GW 400 via a home optical line and a fixed telephone line.

  The eNB 100a configures a macro cell 910a. The eNB 100b configures a macro cell 910b. The HeNB 200a constitutes a micro cell 920a. The HeNB 200b constitutes a micro cell 920b. The HeNB 200c constitutes a micro cell 920c. In addition, the cell which HeNB200a, 200b, 200c comprises is not limited to a microcell, What is necessary is just a cell smaller than a macrocell. For example, it may be a pico cell or a femto cell.

  In the following, for convenience of explanation, when each of the HeNBs 200a, 200b, and 200c is not distinguished, they are simply referred to as “HeNB200”. Similarly, when not distinguishing each of UE300a and 300b, it calls "UE300." Similarly, when the eNBs 100a and 100b are not distinguished from each other, they are referred to as “eNB 100”.

  Next, HeNB200, MME / S-GW400, and HeNB-GW500 are demonstrated.

  The HeNB 200 has three types of access modes (Access Modes), ie, an open mode, a closed mode, and a hybrid mode, as service types to be provided.

  In the open mode, the HeNB 200 is not different from the eNB. Therefore, all UEs can access the HeNB 200. Also, whether the accessed UE is a CSG member or a non-CSG member is not distinguished by the network. More specifically, the HeNB 200 does not broadcast the CSG-ID. Further, the HeNB 200 uses the same PCI (Physical Cell Identity) as the eNB in the open mode.

  In the closed mode, the HeNB 200 permits access only to CSG (Closed Subscriber Group) members. Moreover, HeNB200 uses PCI for CSG. The HeNB 200 broadcasts the CSG-ID by using system information.

  In the hybrid mode, the HeNB 200 can be accessed from all UEs. However, whether or not the HeNB 200 is accessed is a CSG member is distinguished by the network. More specifically, in the hybrid mode, a CSG member can connect to the HeNB 200 as a CSG base station, and a non-CSG member can connect to the HeNB 200 as a base station in an open mode. In general, the HeNB 200 preferentially allocates radio resources to CSG members in the hybrid mode. In the hybrid mode, the HeNB 200 uses the same PCI (Physical Cell Identity) as the eNB. Moreover, HeNB200 broadcasts CSG-ID by system information (System Information).

  Note that, in the open mode, the cell configured by the HeNB 200 is an “open cell”. In the closed mode, the cell configured by the HeNB 200 is a “closed subscriber group cell”. In the case of the hybrid mode, the cell configured by the HeNB 200 is a “hybrid cell”.

  The MME in the MME / S-GW 400 mainly performs UE mobility management, session management, non-access layer signaling processing and security, alarm message transmission, selection of an eNB or HeNB suitable for the alarm message, and the like. The S-GW in the MME / S-GW 400 performs functions such as packet routing and transfer functions, downlink data buffering for idle UEs, and uplink and downlink charging of home routing data during roaming.

The HeNB-GW 500 executes functions such as security authentication. <B. Overview of Processing in Communication System 1>
FIG. 2 is a diagram for explaining processing when the eNB 100a detects congestion in the macro cell 910a that the eNB 100a configures. FIG. 2A is a diagram for explaining a communication state in the communication system 1 before congestion is detected. FIG. 2B is a diagram for explaining a communication state (state after transition) in the communication system 1 after congestion is detected. Note that the MME / S-GW 400 may detect congestion instead of the eNB 100a.

  Referring to FIG. 2A, eNBs 100a and 100b and HeNB-GW 500 are in communication with MME / S-GW 400. The HeNB 200a is in communication with the eNB 100a. HeNB200b, 200c is communicating with HeNB-GW500. That is, HeNB200b, 200c is communicating with MME / S-GW400 via HeNB-GW500. Moreover, UE300a, 300b is communicating with eNB100a. Furthermore, it is assumed that the HeNBs 200a, 200b, and 200c have the service type “closed mode” regarding the UEs 300a and 300b.

  With reference to FIG.2 (b), when congestion is detected in the macrocell 910a by eNB100a, UE300a hands over from HeNB100a to the HeNB200a located in the periphery of UE300a. In this case, the HeNB 200a needs to change the service type from “closed mode” to “open mode” or “hybrid mode” in advance. On the other hand, the UE 300b does not perform handover because there is no HeNB located around the UE 300b.

  Hereinafter, a specific configuration for realizing such a handover process will be described. In the following, for the sake of simplification of description, an outline of processing will be described focusing on the UE 300a out of the UE 300a and the UE 300b.

<C. Data processing>
(C1. Sequence in Communication System 1)
In the following, it is assumed that the HeNB 200 restricts the access of the UE 300 as a premise. That is, HeNB200 shall comprise the CSG cell which does not permit access with respect to UE300.

  FIG. 3 is a sequence chart for explaining the processing of the communication system 1 in the present embodiment. More specifically, FIG. 3 is a diagram for explaining processing performed between the UE 300a, the eNB 100a, the MME / S-GW 400, and the HeNB 200a in the communication system 1.

  With reference to FIG. 3, UE300a and eNB100a are communicating. Moreover, eNB100a and MME / S-GW400 are communicating. Assume that the eNB 100a detects congestion in the sequence SQ2. In sequence SQ4, the eNB 100a transmits, to the UE 300a, a command (a request signal for instructing the search for the HeNB) to detect the HeNB around the UE 300a based on the detected congestion. Specifically, the eNB 100a transmits a conventionally used “measurement request (Measurement Control)” to the UE 300a. The measurement request is for measuring reception quality.

  In sequence SQ6, the UE 300a searches for the HeNB based on the command. In sequence SQ8, the UE 300a notifies the eNB 100a of a search result (Measurement Report) that is a detection result. The eNB 100a receives the search result from the UE 300a.

  When the search result indicates that the HeNB 200a is detected as a neighboring HeNB, in the sequence SQ10, the eNB 100a instructs the MME / S-GW 400 to change the service type of the detected HeNB 200a (service type Change request message). The MME / S-GW 400 receives a command requesting a change of service type from the eNB 100a.

  Here, the command instructs to change the service type from “closed mode” to “open mode” or “hybrid mode”. In other words, the command is a command to change the micro cell 920a configured by the HeNB 200a from the CSG cell to the hybrid cell or the open cell with respect to the detected HeNB 200a. It should be noted that whether to change to “open mode” or “hybrid mode” may be determined in advance in the communication system 1. Alternatively, information specifying the changed service type may be included in the command requesting the change of the service type.

  Next, MME / S-GW 400 transfers a command for requesting change of service type to HeNB 200a in sequence SQ12 based on reception of a command for requesting change (switching) of service type from eNB 100a.

  In this way, the eNB 100a is a case where the HeNB 200a located in the vicinity of the UE 300a is detected, and when the HeNB 200a restricts the access of the UE 300a, a command for requesting the removal of the access restriction in the detected HeNB 200a. Is transmitted to HeNB200a via MME / S-GW400.

  The HeNB 200a changes the service type from “closed mode” to “open mode”, for example, in sequence SQ14 based on the reception of the instruction requesting change of the service type. Based on the change of the service type, the HeNB 200a transmits a response signal (ACK) indicating that the service type has been switched to the MME / S-GW 400 in sequence SQ16 according to the request signal. Specifically, the HeNB 200a determines whether or not the service type can be changed based on the reception of the instruction requesting the change of the service type. Note that the HeNB 200a transmits a switching completion message (ACK) when the change of the service type is allowed, and transmits a switching rejection response (NACK) when the change of the service type is not allowed.

  In sequence SQ18, the MME / S-GW 400 transfers the received ACK signal to the eNB 100a that is the source of the request signal. In sequence SQ20, the eNB 100a transmits a command for instructing the UE 300a to perform handover from the eNB 100a to the HeNB 200a. In sequence SQ22, a handover process is executed. Thus, based on having transmitted the instruction | command which requests | requires the change of a service type, eNB100a performs the process which hands over UE300a to HeNB200a detected from eNB100a using MME / S-GW400. Thereby, UE300a starts communication with HeNB200a.

  As described above, in the present embodiment, the UE 300a (that is, the non-CSG member UE) that cannot be connected by the setting before the change of the service type in the HeNB 200a can be handed over from the eNB 100a to the HeNB 200a. Therefore, the congestion state of the macro cell 910a configured by the eNB 100 can be eliminated. Therefore, the ease of connection of the UE 300a to the base station can be improved.

  Furthermore, since the eNB 100a uses the search result by the UE 300a, the service types of all the HeNBs existing in the service area of the eNB 100a (in the macro cell 910a) are not changed. In other words, the eNB 100a can change the service type of only the minimum necessary HeNB 200 to which the UE 300a is connected and the UE 300a may be connected.

  In addition, it is possible to reduce the processing load on the network in the communication system 1 as compared with the configuration in which the service types of all the HeNBs 200 are changed.

(C2. Control structure in eNB 100a)
FIG. 4 is a flowchart showing the flow of processing in the eNB 100a. With reference to FIG. 4, in step S <b> 2, the eNB 100 a determines whether congestion is detected in the macro cell 910 a configured by the eNB 100 a. When the eNB 100a detects congestion (YES in step S2), in step S4, the eNB 100a requests the UE 300a to search for a HeNB that configures a peripheral CSG cell. When congestion is not detected (NO in step S2), the eNB 100a advances the process to step S2.

  In step S6, the eNB 100a determines whether a search result is received from the UE 300a. When the eNB 100a receives the search result (YES in step S6), in step S8, the eNB 100a issues a command (service type change request message) for requesting change of the service type to the detected HeNB (HeNB 200a in FIG. 3). Send. For example, the eNB 100a requests to change the service type of the detected HeNB from “closed mode” to “open mode”. In other words, the eNB 100a transmits a command for changing the cell configured by the detected HeNB from the CSG cell to the open cell. If the eNB 100a has not received the search result (NO in step S6), the process proceeds to step S6.

  In step S10, the eNB 100a determines whether or not a response (ACK) indicating that the change of the service type has been completed is received from the detected HeNB. When eNB 100a determines that ACK has been received (YES in step S10), in step S12, eNB 100a instructs UE 300a to perform handover to the detected HeNB. eNB100a continues communication with UE300a, when NACK is received and ACK cannot be received (in step S10 NO).

  In step S14, the eNB 100a performs a process of handing over the UE 300a to the HeNB detected from the eNB 100a. When step S14 ends, the eNB 100a ends communication with the UE 300a.

<D. Hardware configuration>
(D1.eNB 100a)
FIG. 5 is a diagram illustrating a typical hardware configuration of the eNB 100a. Referring to FIG. 5, eNB 100 a includes antenna 110, radio processing unit 130, and control / baseband unit 150.

  The radio processing unit 130 includes a duplexer 1301, a power amplifier 1303, a low noise amplifier 1305, a transmission circuit 1307, a reception circuit 1309, and an orthogonal modulation / demodulation unit 1310. The control / baseband unit 150 includes a baseband circuit 151, a control device 152, a power supply device 155, a timing control unit 153, and a communication interface 154. The control device 152 includes a CPU 1521, a ROM 1522, a RAM 1523, a non-volatile memory 1524, and an HDD (Hard Disk Drive) 1525.

  The orthogonal modulation / demodulation unit 1311 performs orthogonal modulation / demodulation on an OFDM (Orthogonal Frequency Division Multiplexing) signal processed by the baseband circuit 151 and converts it into an analog signal (RF (Radio Frequency) signal). The transmission circuit 1307 converts the RF signal generated by the orthogonal modulation / demodulation unit 1311 into a frequency to be transmitted as a radio wave. The receiving circuit 1309 converts the received radio wave into a frequency to be processed by the orthogonal modulation / demodulation unit 1311.

  The power amplifier 1303 amplifies the power of the RF signal generated by the transmission circuit 1307 for transmission from the antenna 110. The low noise amplifier 1305 amplifies the weak radio wave received by the antenna 110 and passes it to the receiving circuit 1309.

  The control device 152 performs control of the entire eNB 100a, call control protocol, and control monitoring. The timing control unit 153 generates various clocks used inside the eNB 100a based on the reference clock extracted from the transmission path or the like.

  The communication interface 154 connects a transmission path such as Ethernet (registered trademark), processes a protocol such as IPsec (Security Architecture for Internet Protocol), IPv6 (Internet Protocol Version 6), etc., and exchanges IP packets.

  The baseband circuit 151 performs conversion (modulation / demodulation) between an IP packet exchanged using the communication interface 154 and an OFDM signal (baseband signal) to be placed on the radio. The baseband signal is exchanged with the wireless processing unit 130.

  The power supply apparatus 155 converts the voltage supplied to the eNB 100a into a voltage used inside the eNB 100a.

  The processing in the eNB 100a is realized by each hardware and software executed by the CPU 1521. Such software may be stored in advance in the HDD 1525 or the like. Further, the software may be stored in a memory card (not shown) or other storage medium and distributed as a program product. Alternatively, the software may be provided as a program product that can be downloaded by an information provider connected to the so-called Internet. Such software is read from the storage medium by an IC card reader / writer or other reading device, or downloaded via the communication interface 154 and then temporarily stored in the HDD 1525. The software is read from the HDD 1525 by the CPU 1521 and further stored in the nonvolatile memory 1524 in the form of an executable program. The CPU 1521 executes the program.

  Each component which comprises eNB100a shown by the figure is a general thing. Therefore, it can be said that the essential part of the present invention is software stored in the HDD 1525, the nonvolatile memory 1524, a memory card or other storage medium, or software that can be downloaded via a network. In addition, since the operation | movement of each hardware of eNB100a is known, detailed description is not repeated.

  The recording media are not limited to DVD-ROM, CD-ROM, FD (Flexible Disk), and hard disk, but are magnetic tape, cassette tape, optical disk (MO (Magnetic Optical Disc) / MD (Mini Disc) / DVD (Digital Versatile Disc), optical card, mask ROM, EPROM (Electronically Programmable Read-Only Memory), EEPROM (Electronically Erasable Programmable Read-Only Memory), flash ROM, etc. . The recording medium is a non-transitory medium that can be read by a computer. The program here includes not only a program directly executable by the CPU but also a program in a source program format, a compressed program, an encrypted program, and the like.

  In addition, since eNB100b and HeNB200a, 200b, 200c which comprise the communication system 1 also have the hardware configuration similar to eNB100a, each hardware configuration of NB100b and HeNB200a, 200b, 200c is not demonstrated repeatedly.

(D2. UE300a)
FIG. 6 is a diagram illustrating a hardware configuration of the UE 300a. Referring to FIG. 6, the UE 300a includes an antenna 301, an RF (Radio Frequency) circuit 302, a baseband circuit 303, a GPS receiver 304, an application processor 305 that executes a program, and a ROM (Read Only Memory). 306, a RAM (Random Access Memory) 307, a NAND flash memory 308, a display 309, a camera 310, a microphone 311, a speaker 312, an operation key 313 for receiving an instruction input by a user, and a communication IF (Interface) 314, an IC (Integrated Circuit) card reader / writer 315, and a power supply unit 316.

  The GPS receiver 304 includes an antenna 3041, an RF circuit 3042, and a baseband circuit 3043. The GPS receiver 304 receives signals from the GPS satellites 91 to 94 using the antenna 3041. Further, the GPS receiver 304 outputs processing results (that is, current location information) in the RF circuit 3042 and the baseband circuit 3043 to the application processor 305. The current location information is information indicating latitude, longitude, and altitude.

  The antenna 301, the RF circuit 302, and the baseband circuit 303 are used for wireless communication with other mobile terminals, fixed telephones, and PCs (Personal Computers) via a base station. Specifically, the antenna 301, the RF circuit 302, and the baseband circuit 303 are used for the UE 300a to perform communication using a mobile phone network.

  The flash memory 308 is a nonvolatile semiconductor memory. The flash memory 308 volatilely stores various programs for controlling the UE 300a and various data such as data generated by the UE 300a and data acquired from an external device of the UE 300a.

  The components 303 to 316 are connected to each other by a data bus. A memory card 1151 is attached to the IC card reader / writer 315.

  The processing in the UE 300a is realized by software executed by each hardware and the application processor 305. Such software may be stored in the flash memory 308 in advance. The software may be stored in a memory card 1151 or other storage medium and distributed as a program product. Alternatively, the software may be provided as a program product that can be downloaded by an information provider connected to the so-called Internet. Such software is read from the storage medium by the IC card reader / writer 315 or other reading device, or downloaded via the antenna 301, the RF circuit 302, and the baseband circuit 303, or the communication IF 314. Once stored in the flash memory 308. The software is read from the flash memory 308 by the application processor 305 and further stored in the flash memory 308 in the form of an executable program. The application processor 305 executes the program.

  Each component which comprises UE300a shown by the figure is common. Therefore, it can be said that the essential part of the present invention is software stored in the flash memory 308, the memory card 1151, and other storage media, or software that can be downloaded via a network. In addition, since the operation | movement of each hardware of UE300a is known, detailed description is not repeated.

  The recording medium is not limited to DVD-ROM, CD-ROM, FD, and hard disk, but is fixed such as semiconductor memory such as magnetic tape, cassette tape, optical disk, optical card, mask ROM, EPROM, EEPROM, and flash ROM. A medium carrying a program may be used. The recording medium is a non-temporary medium that can be read by the computer. The program here includes not only a program directly executable by the CPU but also a program in a source program format, a compressed program, an encrypted program, and the like.

  Note that since the UE 300b has the same hardware configuration as that of the UE 300a, the hardware configuration of the UE 300b will not be repeatedly described here.

(D3. MME / S-GW400)
FIG. 7 is a diagram illustrating a hardware configuration of the MME / S-GW 400. Referring to FIG. 7, MME / S-GW 400 includes, as main components, CPU 401 that executes a program, ROM 402 that stores data in a nonvolatile manner, data generated by execution of the program by CPU 401, or an input device A RAM 403 that stores data input via a device (not shown) volatilely, an HDD 404 that stores data in a nonvolatile manner, an LED 405, a switch 406, a communication IF (Interface) 407, and a power supply circuit 408 including. Each component is connected to each other by a data bus. Note that the communication IF 407 is an interface for communicating with the eNBs 100a and 100b, the HeNB 200a, and the HeNB-GW 500.

  The processing in the MME / S-GW 400 is realized by each hardware and software executed by the CPU 401. Such software may be stored in advance in the HDD 404. The software may be stored in other storage media and distributed as a program product. Alternatively, the software may be provided as a program product that can be downloaded by an information provider connected to the so-called Internet. Such software is read from the storage medium by a reading device or downloaded via, for example, a communication IF (not shown) and then temporarily stored in the HDD 404. The software is read from the HDD 404 by the CPU 401 and stored in the RAM 403 in the form of an executable program. The CPU 401 executes the program.

  Each component which comprises MME / S-GW400 shown by the figure is general. Therefore, it can be said that the essential part of the present invention is RAM 403, HDD 404, software stored in a storage medium, or software downloadable via a network. In addition, since the operation | movement of each hardware of MME / S-GW400 is known, detailed description is not repeated.

  The recording medium is not limited to a DVD-RAM, and a fixed program such as a semiconductor memory such as a DVD-ROM, a CD-ROM, an FD, a hard disk, a magnetic tape, a cassette tape, an optical disk, an EEPROM, and a flash ROM is supported. It may be a medium to be used. The recording medium is a non-temporary medium that can be read by the computer. The program here includes not only a program directly executable by the CPU but also a program in a source program format, a compressed program, an encrypted program, and the like.

  Note that since the HeNB-GW 500 also has the same hardware configuration as the MME / S-GW 400, the hardware configuration of the HeNB-GW 500 will not be repeatedly described here.

<E. Modification>
(E1. First modification)
For example, when searching for a neighboring HeNB (sequence SQ6 in FIG. 3), the UE 300a reports the HeNB as a search result to the currently connected eNB 100a when detecting a HeNB to which the UE 300a cannot connect (HeNB that is not a CSG member). It is assumed that no.

  Therefore, a command (sequence SQ4 in FIG. 3) for detecting a HeNB around the UE 300a notifies the eNB 100a that the detected HeNB has been detected even if access by the UE 300a is restricted. It is preferable to include a command instructing to do so.

  By setting it as such a structure, even if HeNB (HeNB which is not a CSG member) which UE300a cannot connect is detected, it becomes possible to make eNB100a currently connected report the said HeNB as a search result.

  Therefore, the eNB 100a can hand over the UE 300a from the eNB 100a to the HeNB (HeNB 200a in FIG. 3) that could not be connected before.

(E2. Second modification)
The command (service type change request) of sequence SQ12 in FIG. 3 is a command from the network (MME / S-GW 400) side. Therefore, basically, it has been described that the change of the service type in the sequence SQ14 is allowed. However, it is not limited to this. Since the HeNB 200 can be installed by an individual, the HeNB 200 may be configured so that the owner of the HeNB 200 can set whether or not to allow the service type to be changed.

(E3. Third modification)
Next, a process when the UE 300a that has received the HeNB search request detects a plurality of HeNBs as a result of the HeNB search will be described. Hereinafter, a case where the UE 300a detects the HeNBs 200b and 200c will be described as an example. As a premise, it is assumed that the HeNB 200 restricts the access of the UE 300.

  FIG. 8 is a sequence chart for explaining another process in the communication system 1. More specifically, FIG. 8 is a diagram for explaining processing performed between the UE 300a, the eNB 100a, the MME / S-GW 400, and the HeNBs 200b and 200c in the communication system 1.

  With reference to FIG. 8, UE300a and eNB100a are communicating. Moreover, eNB100a and MME / S-GW400 are communicating. Assume that the eNB 100a detects congestion in the sequence SQ102. In sequence SQ104, the eNB 100a transmits a command for detecting the HeNB around the UE 300a to the UE 300a based on the detected congestion.

  In sequence SQ106, UE300a searches HeNB based on the said instruction | command. In sequence SQ108, the UE 300a notifies the eNB 100a of the search result. The eNB 100a receives the search result from the UE 300a.

  When the search result indicates that the HeNBs 200b and 200c are detected as neighboring HeNBs, in the sequence SQ110, the eNB 100a requests the MME / S-GW 400 to change the service types of the detected HeNBs 200b and 200c. Send a command (service type change request message). The MME / S-GW 400 receives a command requesting a change of service type from the eNB 100a. Here, as described above, the command instructs to change the service type from “closed mode” to “open mode” or “hybrid mode”.

  Next, MME / S-GW 400 transfers a command for requesting change of service type to HeNB 200b in sequence SQ112 based on reception of a command for requesting change of service type from eNB 100a. Similarly, in sequence SQ114, MME / S-GW 400 transfers a command requesting change of service type to HeNB 200c.

  In this way, the eNB 100a cancels the access restriction in the detected HeNBs 200b and 200c when the HeNBs 200b and 200c located around the UE 300a are detected and the HeNBs 200b and 200c restrict the access of the UE 300a. Is transmitted to the HeNBs 200b and 200c via the MME / S-GW 400.

  The HeNB 200b changes the service type from “closed mode” to, for example, “open mode” in sequence SQ116 based on the reception of the command requesting the change of the service type. Based on the change of the service type, the HeNB 200b transmits a response signal (ACK) indicating that the service type has been switched to the MME / S-GW 400 in sequence SQ120. Similarly, HeNB 200c changes the service type from “closed mode” to “open mode”, for example, in sequence SQ118 based on the reception of the command requesting the change of service type. Based on the change of the service type, the HeNB 200c transmits a response signal (ACK) indicating that the service type has been switched to the MME / S-GW 400 in sequence SQ122. In addition, HeNB200b, 200c transmits a switching rejection response (NACK) to MME / S-GW400, when change of a service type is not permitted.

  In sequence SQ124, the MME / S-GW 400 transfers a signal (service type change message) indicating that the service type of the HeNBs 200b and 200c has been changed to the eNB 100a that is the source of the request signal.

  In sequence SQ126, the eNB 100a determines a handover destination from the detected HeNBs 200b and 200c. The eNB 100a may determine, for example, based on the reception level (RSRP (Reference Signal Received Power) or the like) included in the search result from the UE 300a, or the service status (load and / or accommodable number of persons) of each HeNB 200b, 200c. ) May be determined based on. Here, as an example, it is assumed that the eNB 100a determines the HeNB 200b as a handover destination.

  In sequence SQ128, the eNB 100a transmits a command instructing the UE 300a to perform handover from the eNB 100a to the HeNB 200b. In sequence SQ130, a handover process is executed. In sequence SQ132, UE 300a transmits an ACK to HeNB 200b. Thus, based on having transmitted the instruction | command which requests the change of service classification, eNB100a performs the process which hands over UE300a to HeNB200b selected from eNB100a using MME / S-GW400. Thereby, UE300a starts communication with HeNB200b.

  In sequence SQ134, the eNB 100a transmits, to the MME / S-GW 400, a service type change request for changing the service type of the HeNB 200c that has not been selected from the “open mode” to the “closed mode”. In sequence SQ136, the service type change request is transferred to HeNB 200c. In sequence SQ138, the HeNB 200c changes the service type from “open mode” to “closed mode”.

  In sequence SQ140, HeNB 200c transmits a response signal (ACK) indicating that the service type has been changed to MME / S-GW 400. In sequence SQ142, MME / S-GW 400 transfers the response signal (ACK) to eNB 100a.

  As described above, when a plurality of HeNBs are detected, the eNB 100a requests that the access restriction in the detected HeNB be released when each of the plurality of HeNBs 200b and 200c is restricted in the access of the UE 300a. The command is transmitted to the detected plurality of HeNBs 200b and 200c. The eNB 100a selects one HeNB from the detected plurality of HeNBs 200b and 200c. The eNB 100a hands over the UE 300a from the eNB 100a to the selected HeNB 200b. Therefore, even when the UE 300a detects a plurality of HeNBs, the eNB 100a can hand over the UE 300a to any HeNB.

  Furthermore, eNB100a is the structure which transmits the instruction | command for instruct | indicating performing access restriction to HeNB200c which was not selected via MME / S-GW400. That is, the eNB 100a transmits a command to restore the HeNB service type that has become the handover destination to the HeNB. Therefore, the eNB 100a can prevent the unnecessary service type from being changed.

[Embodiment 2]
In the present embodiment, a process when the MME / S-GW 400 receives an earthquake early warning will be described. The earthquake early warning is also called ETWS (Earthquake and Tunami Warning System) or PWS (Public Warning System).

  Also in the present embodiment, as in the first embodiment, it is assumed that the HeNB 200 restricts the access of the UE 300 as a premise. That is, HeNB200 shall comprise the CSG cell which does not permit access with respect to UE300.

<A. Overview of Processing in Communication System 1>
FIG. 9 is a sequence chart for explaining processing of the communication system 1 in the present embodiment. More specifically, FIG. 9 is a diagram for describing processing performed between the UE 300a, the eNB 100a, the MME / S-GW 400, and the HeNB 200a in the communication system 1. In the following, it is assumed that the HeNB 200a is located around the UE 300a. For convenience of explanation, it is assumed that the UE 300a is restricted from accessing the HeNB 200 under the management of the MME / S-GW 400.

  With reference to FIG. 9, UE300a and eNB100a are communicating. Moreover, eNB100a and MME / S-GW400 are communicating. Assume that MME / S-GW 400 has received the earthquake early warning in sequence SQ202. In sequence SQ204, the MME / S-GW 400 transmits a command (service type change request message) for requesting a change in the service type of all the HeNBs 200 under the management of the MME / S-GW 400.

  In sequence SQ206, when it is determined that the service type can be changed, the HeNB 200a changes its service type. Each HeNB 200 that has received the service type change request message determines whether or not it is possible to change its own service type. Each HeNB 200 transmits a switching completion message (ACK) to the MME / S-GW 400 when the service type is allowed to be changed, and sends a switching rejection response (NACK) when the service type is not allowed to be changed. It transmits to S-GW400.

  In sequence SQ208, HeNB200a transmits the signal (ACK) which shows having changed the service classification to MME / S-GW400. In addition, also about HeNB200 other than HeNB200a, ACK or NACK is transmitted to MME / S-GW400 according to the presence or absence of a change in service type. In sequence SQ210, the MME / S-GW 400 transfers a signal (service type change message) indicating that the service type of the HeNB 200a has been changed to the eNB 100a that is the source of the request signal. In addition, about HeNB which changed service types other than HeNB200a, respectively, ACK is transmitted to MME / S-GW400 similarly to HeNB200a.

  In sequence SQ212, the eNB 100a transfers the service type change message to the UE 300a. Specifically, the eNB 100a notifies information on the HeNB 200 whose service type has been changed. The notification includes a command (a request signal for instructing a search for HeNB) for detecting a HeNB around the UE 300a.

  In sequence SQ214, UE 300a searches for a HeNB located in the vicinity based on the reception of the service type change message. In sequence SQ216, the UE 300a notifies the eNB 100a of the search result. The eNB 100a receives the search result from the UE 300a.

  In sequence SQ218, the eNB 100a determines whether or not to hand over the UE 300a to the detected HeNB 200 based on the search result. Here, it is assumed that the UE 300a detects only the HeNB 200a. For example, when eNB 100a determines to perform handover, in sequence SQ220, eNB 100a transmits a command to instruct UE 300a to perform handover from eNB 100a to HeNB 200a. In sequence SQ222, a handover process is executed. Thus, based on having transmitted the instruction | command which requests | requires the change of a service type, eNB100a performs the process which hands over UE300a to HeNB200a detected from eNB100a using MME / S-GW400. Thereby, UE300a starts communication with HeNB200a.

  As described above, in the present embodiment, the MME / S-GW 400 sets the service type for all the HeNBs 200 under the management of the MME / S-GW 400 based on the reception of the earthquake early warning, “closed mode”. An instruction to change from “open mode” to “hybrid mode” is transmitted. Therefore, in an emergency, the ease of connection of the UE 300 to the base station can be improved as compared with the normal time.

  In sequence SQ212, the notification of the information of HeNB 200 whose service type has been changed includes a command (specifically, a measurement request (Measurement Control)) for detecting a HeNB around UE 300a as an example. Although described above, the present invention is not limited to this. The configuration may be such that the measurement request is transmitted without notifying the information of the HeNB 200 whose service type has been changed. In addition, the above notification may include System Signal change and change notification, and a new Signaling Message / information element for notifying PCI.

<B. Summary>
As described above, the eNB 100a sends a notification indicating that the plurality of HeNBs 200 managed by the MME / S-GW 400 have released the access restriction of the UE 300 based on the fact that the MME / S-GW 400 has received the earthquake early warning. And received via the MME / S-GW 400. Based on the reception of the notification, the eNB 100a transmits a command for detecting the HeNB 200 installed around the UE 300a among the plurality of base stations HeNB 200 to the UE 300a. The eNB 100a receives the detection result from the UE 300a based on the transmission of the command. Based on the detection of the HeNB 200a, the eNB 100a hands over the UE 300a from the eNB 100a to the detected HeNB 200a using the MME / S-GW 400. Therefore, as described above, in an emergency, the ease of connection of the UE 300 to the base station can be improved compared to the normal time.

  Moreover, eNB100a is also the structure which transmits further the information showing HeNB200 which canceled access restrictions to UE300a based on the said notification having been received. Therefore, UE300a should just report reception quality to eNB100a only about HeNB200 which canceled access restriction among neighboring HeNB200. Furthermore, UE300a should just measure reception quality only about HeNB200 which cancelled | released access restriction among the neighboring HeNB200.

  The notification is preferably a notification indicating that the access restriction has been released for the eNB 100a installed in the macro cell 910a among the plurality of HeNBs 200. Therefore, the MME / S-GW 400 does not need to notify the eNB 100a that the HeNB 200 that is not under the management of the eNB 100a has released access. Therefore, the communication load in the communication system 1 can be reduced as compared with the configuration in which the HeNB 200 that is not under the management of the eNB 100a notifies the eNB 100a that the access has been canceled.

  In addition, the said notification is a notification showing having changed the micro cell 920a comprised by HeNB200a from the closed subscriber group cell to the hybrid cell or the open cell.

[Embodiment 3]
In the first and second embodiments, the configuration has been described in which handover is performed from the eNB 100 to the HeNB 200 when congestion is detected or an emergency earthquake warning is received. In the present embodiment, a configuration is described in which handover is performed from the HeNB 200 to the eNB 100 when congestion is detected.

<A. Overview of Processing in Communication System 1>
FIG. 10 is a diagram for explaining processing when the eNB 100a detects congestion in the micro cell 920a (see FIG. 1) configured by the HeNB 200a. FIG. 10A is a diagram for explaining a communication state in the communication system 1 before congestion is detected. FIG. 10B is a diagram for explaining a communication state (state after transition) in the communication system 1 after congestion is detected. Note that the MME / S-GW 400 may detect congestion instead of the HeNB 200a.

  With reference to Fig.10 (a), eNB100a, 100b and HeNB-GW500 are communicating with MME / S-GW400. The HeNB 200a is in communication with the eNB 100a. HeNB200b, 200c is communicating with HeNB-GW500. That is, HeNB200b, 200c is communicating with MME / S-GW400 via HeNB-GW500. Moreover, UE300b is communicating with eNB100a. UE300a, 300c is communicating with HeNB200a.

  Also, assume that the HeNBs 200a, 200b, and 200c have the service type “open mode” with respect to the UEs 300a, 300b, and 300c. That is, HeNB200 shall comprise the open cell which permits access with respect to UE300. The service type is not limited to “open mode”, but may be “hybrid mode”. In this case, HeNB200 comprises the hybrid cell which permits access with respect to UE300. Hereinafter, a case will be described as an example where UE 300a is not a CSG member of HeNB 200a and UE 300c is a CSG member of HeNB 200a.

  With reference to FIG.10 (b), when congestion is detected in the micro cell 920a which HeNB200a comprises, UE300a hands over from eNB200a to eNB100a located in the periphery of UE300a. On the other hand, since UE 300c is a CSG member of HeNB 200a, handover is not performed even if congestion is detected. Note that the UE 300b does not perform handover because congestion has not occurred in the eNB 100a.

  Hereinafter, a specific configuration for realizing such a handover process will be described. In addition, for the sake of simplification of description, an outline of processing will be described focusing on the UE 300a among the UEs 300a, 300b, and 300c.

<B. Data processing>
FIG. 11 is a sequence chart for explaining the processing of the communication system 1 in the present embodiment. More specifically, FIG. 11 is a diagram for explaining processing performed between the UE 300a, the HeNB 200a, the MME / S-GW 400, and the eNB 100a in the communication system 1.

  With reference to FIG. 11, UE300a and HeNB200a are communicating. Moreover, HeNB200a and MME / S-GW400 are communicating. It is assumed that the HeNB 200a detects congestion in the sequence SQ302. In sequence SQ304, the HeNB 200a determines whether or not the service type of the HeNB 200a can be changed. Specifically, the HeNB 200a determines whether or not the current service type “open mode” can be changed to the “closed mode”. For example, the HeNB 200a acquires the communication status around the HeNB 200a using the MME / S-GW 400, and determines whether the service type can be changed based on the communication status. Alternatively, the HeNB 200a measures the strength (reception quality) of radio waves received from neighboring base stations of the HeNB 200a, and determines whether or not the service type can be changed based on the measured strength. Hereinafter, a case where the service type can be changed will be described as an example.

  In sequence SQ306, HeNB200a transmits the instruction | indication (request signal which instruct | indicates search of eNB) for detecting eNB of the periphery of UE300a with respect to UE300a. Specifically, the HeNB 200a transmits a conventionally used “measurement control (Measurement Control)” to the UE 300a. The measurement request is for the UE 300a to measure the reception quality.

  In sequence SQ308, the HeNB 200a transmits a signal (service type changeable message) indicating that the service type of the HeNB 200a can be changed to the MME / S-GW 400. The MME / S-GW 400 can determine that the service type of the HeNB 200a can be changed to the closed mode by receiving the message.

  In sequence SQ310, UE300a searches for eNB based on the said instruction | command. In sequence SQ312, UE300a notifies HeNB200a of a search result (Measurement Report) which is a detection result. The HeNB 200a receives the search result from the UE 300a.

  When the search result indicates that the eNB 100a is detected as a neighboring base station, in sequence SQ314, the HeNB 200a transmits a command for instructing the UE 300a to perform handover from the HeNB 200a to the eNB 100a. In sequence SQ316, a handover process using MME / S-GW 400 is executed. Thus, HeNB200a performs the process which hands over UE300a to eNB100a detected from HeNB200a using MME / S-GW400 based on having transmitted the service type change possible message to MME / S-GW400. Thereby, UE300a starts communication with eNB100a.

  Therefore, when congestion occurs in the HeNB 200a, the HeNB 200a can improve the communication quality between the UE 300c that is a CSG member and the HeNB 200a by handing over the UE 300a that is not a CSG member to the other base station. That is, communication quality with the HeNB 200a can be improved for the UE 300c that is always permitted to access the HeNB 200a.

<C. Summary>
As described above, the HeNB 200a defines the micro cell 920a for the UE 300a subject to access restriction based on the fact that congestion is detected in the micro cell 920a configured by the HeNB 200a in a state where access restriction is not performed. A command for detecting neighboring base stations of the UE 300a configuring different cells is transmitted. The HeNB 200a receives the detection result from the UE 300a that is subject to access restriction based on the transmission of the command. The HeNB 200a uses the MME / S-GW 400 to hand over the UE 300a to the neighboring base station detected from the HeNB 200a based on the fact that the UE 300a that is subject to access restriction detects the neighboring base station. Based on the handover, the HeNB 200a switches the state of the HeNB 200a from a state in which access restriction is not performed to a state in which access restriction is performed on the UE 00a subject to access restriction. Therefore, as described above, the HeNB 200a can improve the communication quality with the HeNB 200a for the UE 300 that is always permitted to access the HeNB 200a excluding the UE 300a.

<D. Modification>
In the above description, the configuration in which the handover of the UE 300a is performed using the detection of congestion as a trigger has been described as an example, but the present invention is not limited to this. Instead of detecting congestion, based on the detection of a decrease in the quality of service of the UE 300c that is not subject to access restriction, the UE 300a that constitutes a cell different from the micro cell 920a with respect to the UE 300a subject to the access restriction. The HeNB 200a may be configured to transmit a command for detecting neighboring base stations.

  In addition, in FIG. 11, the configuration in which the UE 300a detects the eNB (that is, the configuration in which the base station configuring the macro cell is detected) has been described as an example, but the configuration is not limited thereto. The communication system 1 may be configured to detect an open mode HeNB, a hybrid mode HeNB, and / or a closed mode HeNB to which the UE 300a is connectable instead of detecting the eNB or together with the eNB detection. .

  The embodiment disclosed this time is an exemplification, and the present invention is not limited to the above contents. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1 Communication system, 910a, 910b Macro cell, 920a, 920b, 920c Micro cell, 100a, 100b eNB, 200a, 200b, 200c HeNB, 300a, 300b, 300c UE, 400 MME / S-GW, 500 HeNB-GW.

Claims (26)

A base station communicating with a mobile station and a mobility management entity,
Based on the detection of congestion in the first cell constituted by the base station, a first command for detecting a neighboring base station constituting a second cell narrower than the first cell, First transmission means for transmitting to the mobile station;
Receiving means for receiving the detection result from the mobile station based on the transmission of the first command;
When the neighboring base station is detected, and when the neighboring base station restricts access of the mobile station, a second for requesting release of access restriction in the detected neighboring base station A second transmitting means for transmitting a command to the neighboring base station via the mobility management entity;
Handover control means for handing over the mobile station from the base station constituting the first cell to the detected neighboring base station using the mobility management entity based on the transmission of the second command; A base station.   The first command indicates to the base stations constituting the first cell that the detected neighboring base station has detected the neighboring base station even when access by the mobile station is restricted. The base station according to claim 1, comprising a command for instructing notification.   The base station according to claim 1, further comprising detection means for detecting the congestion. When a plurality of neighboring base stations are detected, when each of the plurality of neighboring base stations restricts access of the mobile station, the second transmitting means detects the second command. Send to multiple neighboring base stations,
The handover control unit selects one neighboring base station from the detected plurality of neighboring base stations, and hands over the mobile station from the base station configuring the first cell to the selected neighboring base station. The base station according to claim 1.   The second transmission means transmits, via the mobility management entity, a third command for instructing to perform the access restriction to the non-selected neighboring base stations. 4. A base station according to 4.   The second command is a command to change the second cell formed by the neighboring base station from a closed subscriber group cell to a hybrid cell or an open cell with respect to the detected neighboring base station. The base station according to any one of 1 to 5. The first cell is a macro cell;
The base station according to claim 1, wherein the second cell is a micro cell, a pico cell, or a femto cell. A base station that communicates with a mobile station and a mobility management entity and constitutes a first cell;
On the basis of the fact that the mobility management entity has received the earthquake early warning, a plurality of base stations each configuring a second cell that is narrower than the first cell managed by the mobility management entity include the mobility Receiving means for receiving a notification indicating that the access restriction of the station has been released via the mobility management entity;
Based on the reception of the notification, an instruction for detecting a neighboring base station installed around the mobile station among the plurality of base stations constituting the second cell to the mobile station Transmitting means for transmitting
Receiving means for receiving the detection result from the mobile station based on the transmission of the command;
Handover control means for handing over the mobile station from the base station constituting the first cell to the detected peripheral base station using the mobility management entity based on the detection of the peripheral base station; A base station.   The base station according to claim 8, wherein the transmission unit further transmits to the mobile station information representing the base station from which the access restriction has been released based on the reception of the notification.   9. The notification is a notification indicating that the access restriction has been released for a base station installed in the first cell among a plurality of base stations constituting the second cell. Or the base station of 9.   The base station according to claim 8, wherein the notification is a notification indicating that the second cell is changed from a closed subscriber group cell to a hybrid cell or an open cell. The first cell is a macro cell;
The base station according to claim 8, wherein the second cell is a micro cell, a pico cell, or a femto cell. A base station that communicates with a plurality of mobile stations and a mobility management entity and is capable of individually restricting access to each of the plurality of mobile stations;
In a state where the access restriction is not performed, congestion is detected in the first cell configured by the base station, or a decrease in service quality of a mobile station not subject to the access restriction is detected. And a transmission means for transmitting to the mobile station subject to the access restriction a command for detecting a neighboring base station of the mobile station constituting a second cell different from the first cell; ,
Receiving means for receiving the detection result from the mobile station subject to the access restriction based on the transmission of the command;
Based on the detection of the neighboring base station by the mobile station subject to the access restriction, the handover is performed to hand over the mobile station from the base station to the detected neighboring base station using the mobility management entity. Control means;
Switching means for switching the state of the base station from the state where the access restriction is not performed to the state where the access restriction is performed on the mobile station subject to the access restriction based on the handover. base station.   Before transmitting the command, whether or not it is possible to change the state of the base station from a state in which the access restriction is not performed to a state in which the access restriction is applied to the mobile station subject to the access restriction. The base station according to claim 13, further comprising determination means for determining. Using the mobility management entity, further comprising an acquisition means for acquiring a communication status around the base station;
The base station according to claim 13 or 14, wherein the determination unit determines whether or not the change is possible based on the acquired communication status. The base station further comprises measurement means for measuring the strength of radio waves received from the base stations around the base station,
The base station according to claim 13 or 14, wherein the determination unit determines whether the change is possible based on the measured intensity. The second cell is a macro cell;
The base station according to any one of claims 13 to 16, wherein the first cell is a micro cell, a pico cell, or a femto cell. A mobile station; a first base station that constitutes the first cell; a second base station that constitutes a second cell that is narrower than the first cell; the first base station; A mobility management entity that manages two base stations,
The first base station is
A first command for detecting the second base station is transmitted to the mobile station based on the detection of congestion in the first cell configured by the first base station. Including one transmission means,
The mobile station
Detecting means for detecting the second base station based on receiving the first command from the first base station;
Second transmission means for transmitting the detection result to the first base station;
The first base station is
Second receiving means for receiving the detection result from the mobile station;
When the second base station is detected and the second base station restricts access to the mobile station, a request is made to release the access restriction at the detected second base station. And a third transmission means for transmitting a second command to the second base station via the mobility management entity,
The second base station is
Release means for releasing the access restriction based on receiving the second instruction;
Notification means for notifying the first base station via the mobility management entity that the access restriction has been released,
The first base station is
A communication system further comprising handover control means for handing over the mobile station from the first base station to the detected second base station using the mobility management entity based on receiving the notification; . A first base station that constitutes the first cell; a plurality of second base stations that each constitute a second cell that is narrower than the first cell; and the first base A communication system comprising a station and a mobility management entity for managing the second base station,
The mobility management entity is:
A receiving means for receiving the earthquake early warning;
When each of the plurality of second base stations restricts access of the mobile station, the mobile station in each of the plurality of second base stations is based on reception of the earthquake early warning. First transmission means for transmitting to the second base station a first command for requesting release of the access restriction of
The second base station is
Release means for releasing access restriction of the mobile station based on receiving the first command;
A second transmission means for transmitting a notification indicating that the access restriction has been released to the first base station via the mobility management entity;
The first base station is
Based on the reception of the notification, a second command for detecting a peripheral base station installed around the mobile station among the plurality of second base stations is transmitted to the mobile station. And a third transmitting means
The mobile station
Detecting means for detecting the neighboring base station based on receiving the second command;
And fourth transmission means for transmitting the detection result to the first base station,
The first base station is
And further comprising a handover control means for handing over the mobile station from the first base station to the detected peripheral base station using the mobility management entity based on the detection of the peripheral base station. system. Manages a plurality of mobile stations, a first base station that constitutes the first cell, a second base station that constitutes a second cell, the first base station, and the second base station A mobility management entity that includes:
The first base station is
A base station capable of individually limiting access to each of the plurality of mobile stations,
The access restriction target based on the detection of congestion in the first cell configured by the first base station or a drop in service quality of the mobile station not subject to the access restriction. First transmission means for transmitting a command for detecting the second base station to the mobile station
The mobile station subject to the access restriction is
Detecting means for detecting a second base station based on receiving the command from the first base station;
Second transmission means for transmitting the detection result to the first base station;
The first base station is
Based on the detection of the second base station by the mobile station subject to the access restriction, the mobile station is moved from the first base station to the detected second base station using the mobility management entity. Handover control means for handing over to a base station;
Switching means for switching the state of the first base station from a state where the access restriction is not performed to a state where the access restriction is applied to the mobile station subject to the access restriction based on the handover. Including a communication system. A communication method in a base station that communicates with a mobile station and a mobility management entity,
Based on the detection of congestion in the first cell constituted by the base station, a first command for detecting a neighboring base station constituting a second cell narrower than the first cell, Transmitting to the mobile station;
Receiving the detection result from the mobile station based on the transmission of the first command;
When the neighboring base station is detected, and when the neighboring base station restricts access of the mobile station, a second for requesting release of access restriction in the detected neighboring base station Sending a command to the neighboring base station via the mobility management entity;
And handing over the mobile station from the base station constituting the first cell to the detected neighboring base station using the mobility management entity based on the transmission of the second command. ,Communication method. A communication method in a base station that communicates with a mobile station and a mobility management entity and constitutes a first cell,
On the basis of the fact that the mobility management entity has received the earthquake early warning, a plurality of base stations each configuring a second cell that is narrower than the first cell managed by the mobility management entity include the mobility Receiving via the mobility management entity a notification indicating that the station access restriction has been removed;
Based on the reception of the notification, an instruction for detecting a neighboring base station installed around the mobile station among the plurality of base stations constituting the second cell to the mobile station A step of sending
Receiving means for receiving the detection result from the mobile station based on the transmission of the command;
Handing over the mobile station from the base station constituting the first cell to the detected peripheral base station using the mobility management entity based on the detection of the peripheral base station. ,Communication method. A communication method in a base station that communicates with a plurality of mobile stations and a mobility management entity and can individually restrict access to each of the plurality of mobile stations,
In a state where the access restriction is not performed, congestion is detected in the first cell configured by the base station, or a decrease in service quality of a mobile station not subject to the access restriction is detected. A command for detecting a base station in the vicinity of the mobile station constituting a second cell different from the first cell, to the mobile station subject to the access restriction,
Receiving the detection result from the mobile station subject to the access restriction based on the transmission of the command;
Step of handing over the mobile station from the base station to the detected peripheral base station using the mobility management entity based on detection of the peripheral base station by the mobile station subject to the access restriction When,
Switching the state of the base station from the state where the access restriction is not performed to the state where the access restriction is applied to the mobile station subject to the access restriction based on the handover. Method. A program for controlling a base station that communicates with a mobile station and a mobility management entity,
Based on the detection of congestion in the first cell constituted by the base station, a first command for detecting a neighboring base station constituting a second cell narrower than the first cell, Transmitting to the mobile station;
Receiving the detection result from the mobile station based on the transmission of the first command;
When the neighboring base station is detected, and when the neighboring base station restricts access of the mobile station, a second for requesting release of access restriction in the detected neighboring base station Sending a command to the neighboring base station via the mobility management entity;
Handing over the mobile station from the base station constituting the first cell to the detected neighboring base station using the mobility management entity based on transmitting the second command; A program to be executed by a base station processor. A program for communicating with a mobile station and a mobility management entity and for controlling a base station constituting the first cell,
On the basis of the fact that the mobility management entity has received the earthquake early warning, a plurality of base stations each configuring a second cell that is narrower than the first cell managed by the mobility management entity include the mobility Receiving via the mobility management entity a notification indicating that the station access restriction has been removed;
Based on the reception of the notification, an instruction for detecting a neighboring base station installed around the mobile station among the plurality of base stations constituting the second cell to the mobile station A step of sending
Receiving means for receiving the detection result from the mobile station based on the transmission of the command;
Handing over the mobile station from the base station constituting the first cell to the detected peripheral base station using the mobility management entity based on the detection of the peripheral base station; A program to be executed by a processor of the base station. A program for controlling a base station that communicates with a plurality of mobile stations and a mobility management entity and can individually restrict access to each of the plurality of mobile stations,
In a state where the access restriction is not performed, congestion is detected in the first cell configured by the base station, or a decrease in service quality of a mobile station not subject to the access restriction is detected. A command for detecting a base station in the vicinity of the mobile station constituting a second cell different from the first cell, to the mobile station subject to the access restriction,
Receiving the detection result from the mobile station subject to the access restriction based on the transmission of the command;
Step of handing over the mobile station from the base station to the detected peripheral base station using the mobility management entity based on detection of the peripheral base station by the mobile station subject to the access restriction When,
Switching the state of the base station from the state where the access restriction is not performed to the state where the access restriction is performed for the mobile station subject to the access restriction based on the handover. A program to be executed by the station processor.

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