JP2010226704A - Wireless communication system, radio base station, network device and blockade control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent deterioration in the quality of communication services by preventing a communication disabled area from being generated, by widening a communication area of a second radio base station when a communication area of a first radio base station becomes narrow. <P>SOLUTION: A radio base station 1, which is to be pre-blockaded, transmits a notification of pre-blockade commencement to radio base stations 2A-2F existing around the radio base station 1. Further, the radio base station 1 reduces the transmission power thereof at a predetermined reduction rate at a time of pre-blockade commencement. Meanwhile, each of the radio base stations 2A-2F receives the notification of pre-blockade commencement and increases, at the time of pre-blockade commencement, the transmission power at a predetermined increase rate the absolute value of which is equal to that of the predetermined reduction rate at the radio base station 1. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a radio communication system including a plurality of radio base stations, a radio base station in the radio communication system, a network device in a higher rank of the radio base station, and a block control method in the radio communication system.

  In a wireless communication system, when maintenance or the like of a wireless base station is performed, the wireless base station performs processing (blocking processing) for stopping transmission power. In this blocking process, the radio base station does not accept a new call indicating a call that is newly generated by the radio terminal. In addition, when there is an existing call indicating a call that is continuing communication between the radio terminal and the radio base station, the radio base station waits for the existing call to end, and transmits the transmission power after the end. To stop. Such a process of waiting for the end of the existing call is referred to as a pre-blocking process. However, if an existing call exists even after a predetermined time has elapsed from the start of the blocking process, the radio base station forcibly disconnects the existing call and stops transmission power (for example, see Patent Document 1). . Alternatively, when there is an existing call indicating a call that is continuing communication between the radio base station and the radio terminal, the radio base station performs handover of the existing call to another adjacent radio base station. Then, the transmission power is stopped (see, for example, Patent Document 2). Further, from the viewpoint of energy saving, it has been proposed to reduce the transmission power of a radio base station in a time zone with a small amount of communication such as at night.

JP 2006-5395 A Japanese Patent Laid-Open No. 10-209947

  However, in the above-described conventional blocking process technique, even if the wireless terminal is located in the communication area (cell) of the wireless base station before the blocking process, if the wireless terminal is located outside the cell range by the blocking process, New calls that could be accepted before the blocking process are not accepted. In other words, due to the blockage, an area where the communication service cannot be received occurs.

  Alternatively, when the wireless terminal is located outside the cell area due to the blocking process, the wireless terminal is located in the vicinity of the blocked wireless base station, in other words, the wireless terminal is located at a position away from the wireless terminal. The wireless base station is requested to accept a new call, and even if the new call is accepted, the communication quality may deteriorate.

  Further, in the conventional blocking processing method described above, the existing call is forcibly disconnected when a predetermined time elapses from the start of the blocking processing, resulting in deterioration of the quality of the communication service.

  Further, when maintenance work is performed by stopping a plurality of radio base stations constituting the radio communication system one by one, it takes a long time until the maintenance work of all the radio base stations is completed. On the other hand, in order to shorten the maintenance work time, it is conceivable to simultaneously stop the transmission power of a plurality of radio base stations. However, if two adjacent radio base stations simultaneously stop transmission power, a wide dead zone may occur. Similarly, when reducing the transmission power of a radio base station from the viewpoint of energy saving, if a plurality of adjacent radio base stations simultaneously stop transmission power, a wide dead zone may occur.

  In view of the above problems, an object of the present invention is to provide a radio communication system, a radio base station, a network device, and a blockage control method that prevent deterioration in quality of communication services.

  In order to solve the above-described problems, the present invention has the following features. First, a first feature of the present invention is a wireless communication system (wireless communication system 10) including a plurality of wireless base stations (wireless base station 1, wireless base stations 2A to 2F), wherein the first wireless base station is A storage unit (storage unit 103) that stores information of the second radio base station, and the pre-occlusion is started based on the information of the second radio base station stored in the storage unit A pre-occlusion start notification transmission unit (pre-occlusion start notification transmission processing unit 154) that transmits a pre-occlusion start notification indicating the start of pre-occlusion to the second radio base station, and a transmission power reduction process that reduces transmission power Unit (transmission power reduction processing unit 156), the second radio base station receiving a pre-occlusion start notification receiving unit (pre-occlusion start notification receiving processing unit 162), and the pre-occlusion The pre-occlusion start notification is received by the start notification receiver. There when it is received, and summarized in that and a transmission power increase process unit to increase the transmission power (transmission power increase process unit 166).

  In such a radio communication system, the first radio base station to be preoccluded decreases the transmission power, while the second radio base stations around the first radio base station increase the transmission power. Therefore, when the communication area of the first radio base station is narrowed, the communication area of the second radio base station is widened, thereby preventing the occurrence of an incommunicable area, thereby degrading the quality of the communication service. Absent.

  A second feature of the present invention relates to the first feature of the present invention, wherein the transmission power reduction processing unit reduces the transmission power by a predetermined amount within a predetermined time, and the transmission power increase processing unit The transmission power is increased by the predetermined amount within the time.

  A third feature of the present invention relates to the first or second feature of the present invention, wherein the first radio base station measures a distance between the own radio base station and the second radio base station. (Distance measuring unit 152), and the pre-occlusion start notification transmitting unit transmits the pre-occlusion start notification to the second radio base station whose distance measured by the distance measuring unit is equal to or less than a predetermined threshold. The gist is to do.

  A fourth feature of the present invention relates to any one of the first to third features of the present invention, wherein the second radio base station specifies a direction specifying unit (direction specifying) that specifies the direction of the first radio base station. 164), and the transmission power increase processing unit increases the transmission power in the direction of the first radio base station specified by the direction specifying unit.

  A fifth feature of the present invention relates to any one of the first to fourth features of the present invention, wherein the first radio base station is configured to receive the second radio when there is no longer an existing call in the own radio base station. An existing call non-existence notification transmission unit (existing call non-existence notification transmission processing unit 158) that transmits to the base station an existing call non-existence notification indicating that there is no existing call, and the second radio base station includes: An existing call non-existence notification receiving unit (existing call non-existence notification receiving processing unit 168) that receives the existing call non-existing notification, and the transmission power increase processing unit is configured to receive the existing call by the existing call non-existence notification receiving unit. The gist is to stop the increase in the transmission power when the absence notification is received.

  A sixth feature of the present invention relates to any one of the first to fifth features of the present invention, and comprises a base station control device that connects and controls the first radio base station and the second radio base station. The pre-blocking start notification transmitting unit transmits the pre-blocking start notification to the second radio base station via the base station control device.

  A seventh feature of the present invention relates to any one of the first to sixth features of the present invention, wherein the plurality of radio base stations belong to different groups, and a time zone in which the transmission power is reduced in the radio base station. The gist is that it differs for each group.

  In such a wireless communication system, two adjacent wireless base stations belong to different groups, and the time periods during which the transmission power decreases are different. Therefore, as a result of two adjacent radio base stations stopping transmission power at the same time, a wide dead zone does not occur, and the transmission power of the radio base station is reduced while suppressing deterioration of the quality of communication service. Is possible.

  According to an eighth aspect of the present invention, there is a network device (base station control device 6) in a higher rank than the plurality of radio base stations, and the network device includes four of the plurality of radio base stations according to a predetermined condition. The gist is to include a grouping processing unit (grouping processing unit 254) that performs grouping into the above groups.

  A ninth feature of the present invention relates to the seventh or eighth feature of the present invention, wherein the radio base station is configured such that when another radio base station is added to the radio communication system, or another radio base station When a station is excluded from the wireless communication system, a regrouping processing unit (regrouping processing unit) that performs regrouping processing to divide the plurality of wireless base stations into groups again using inter-base station communication 176).

  A tenth feature of the present invention is a radio base station constituting a radio communication system, and a storage unit for storing information of other radio base stations located in the vicinity of the own radio base station, and pre-blocking are started. In this case, the pre-blocking is transmitted to the other radio base station specified based on the information of the other radio base station stored in the storage unit. The gist is to include a start notification transmission unit and a transmission power reduction processing unit that reduces transmission power.

  An eleventh feature of the present invention is a wireless base station constituting a wireless communication system, and a pre-blocking start notification indicating that pre-blocking is started in the other wireless base station from another wireless base station And a transmission power increase processing unit that increases transmission power when the pre-occlusion start notification is received by the pre-occlusion start notification reception unit.

  A twelfth feature of the present invention relates to the tenth or eleventh feature of the present invention, and is divided into a plurality of groups together with other radio base stations so that two adjacent radio base stations belong to different groups. The gist of the present invention is to provide a transmission power control unit (transmission power control unit 174) that reduces transmission power in the same time zone as other radio base stations belonging to the same group as the own radio base station.

  A thirteenth feature of the present invention is a network device in a higher rank of a plurality of radio base stations constituting a radio communication system, wherein the plurality of radio base stations are divided into four or more groups according to a predetermined condition And a grouping processing unit (grouping processing unit 254) that performs transmission, and a time zone during which transmission power decreases in the radio base station is different for each group.

  A fourteenth feature of the present invention is a block control method in a radio communication system including a plurality of radio base stations, and the first radio base station stores the above-mentioned data stored in a storage unit when pre-blocking is started. A step of transmitting a pre-blocking start notification indicating the start of pre-blocking to the second wireless base station specified based on the information of the second wireless base station; Reducing the transmission power when the second radio base station receives the pre-occlusion start notification and the second radio base station receives the pre-occlusion start notification. And a step.

  According to the present invention, the quality of communication service is not deteriorated.

1 is an overall schematic configuration diagram of a radio communication system according to a first embodiment of the present invention. 1 is a configuration diagram of a radio base station according to a first embodiment of the present invention. It is a 1st functional block block diagram of the control part in the wireless base station which concerns on 1st Embodiment of this invention. It is a figure which shows an example of the positional information on another radio base station. It is a figure which shows an example of the pre-occlusion start notification. It is a figure which shows an example of the existing call absence notification. It is a 2nd functional block block diagram of the control part in the wireless base station which concerns on 1st Embodiment of this invention. It is a sequence diagram which shows operation | movement of the radio | wireless communications system which concerns on 1st Embodiment of this invention. 1 is an overall schematic configuration diagram of a wireless communication system in a pre-blocking process according to a first embodiment of the present invention. It is a whole schematic block diagram of the radio | wireless communications system which concerns on 2nd Embodiment of this invention. It is a block diagram of the network apparatus which concerns on 2nd Embodiment of this invention. It is a figure which shows an example of adjacent base station information. It is a figure which shows an example of grouping information. It is a functional block block diagram of the control part in the wireless base station which concerns on 2nd Embodiment of this invention. It is a sequence diagram which shows the operation | movement of the initial grouping of the radio | wireless communications system which concerns on 2nd Embodiment of this invention. It is a flowchart which shows the operation | movement of the regrouping of the radio base station which concerns on 2nd Embodiment of this invention.

(First embodiment)
Next, a first embodiment of the present invention will be described with reference to the drawings. Specifically, (1) the configuration of the wireless communication system, (2) the operation of the wireless communication system, (3) the operation and effect, and (4) other embodiments will be described. In the description of the drawings in the first embodiment below, the same or similar parts are denoted by the same or similar reference numerals.

(1) Configuration of Radio Communication System First, regarding the configuration of the radio communication system according to the first embodiment of the present invention, (1.1) overall schematic configuration of radio communication system, (1.2) configuration of radio base station This will be explained in order.

(1.1) Overall Schematic Configuration of Radio Communication System FIG. 1 is an overall schematic configuration diagram of a radio communication system 10 according to the first embodiment of the present invention.

  As shown in FIG. 1, the radio communication system 10 includes a radio base station 1, radio base stations 2 </ b> A to 2 </ b> F located around the radio base station 1, and a base station control device 6. The wireless communication system 10 provides a wireless communication service to the wireless terminal 5.

  The radio base station 1 transmits a radio signal with a predetermined transmission power and provides a cell 3 as a communication area. Similarly, the radio base stations 2A to 2F transmit radio signals with predetermined transmission power, respectively, and provide cells 4A to 4F as communication areas. These cells 4A to 4F are radially divided into a plurality of sectors (not shown) around the radio base stations 2A to 2F. In FIG. 1, the wireless terminal 5 is located in a cell 3 provided by the wireless base station 1. For this reason, the radio | wireless terminal 5 can transmit and receive a radio signal between radio base stations.

  The base station control device 6 controls the radio base station 1 and the radio base stations 2A to 2F. The base station control device 6 connects the radio base station 1 and the radio base stations 2A to 2F by a wired line (not shown).

(1.2) Configuration of Radio Base Station FIG. 2 is a configuration diagram of the radio base station 1. As illustrated in FIG. 2, the wireless base station 1 includes a control unit 102, a storage unit 103, a wired communication unit 104, a wireless communication unit 106, and an antenna 108. The radio base stations 2A to 2F have the same configuration as the radio base station 1.

  The control unit 102 is configured by a CPU, for example, and controls various functions provided in the radio base station 1. The storage unit 103 is configured by a memory, for example, and stores various types of information used for control and the like in the radio base station 1.

  The wired communication unit 104 transmits and receives data to and from the base station control device 6. The wireless communication unit 106 includes an RF circuit, a baseband circuit, etc., performs modulation and demodulation, encoding and decoding, etc., and transmits and receives wireless signals to and from the wireless terminal 5 via the antenna 108. .

  FIG. 3 is a functional block configuration diagram of the control unit 102 in the radio base station 1. As shown in FIG. 3, the control unit 102 in the radio base station 1 includes a distance measurement unit 152, a pre-blocking start notification transmission processing unit 154, a transmission power reduction processing unit 156, and an existing call absence notification transmission processing unit 158. .

  The distance measuring unit 152 measures the distance between the radio base station 1 and another radio base station.

  Specifically, the storage unit 103 stores the longitude and latitude of the wireless base station 1 that is the own wireless base station. Further, the storage unit 103 stores position information of other radio base stations. FIG. 4 is a diagram illustrating an example of position information of another radio base station. The position information of the other radio base station shown in FIG. 4 includes the ID (base station ID) of the corresponding radio base station, and the longitude and latitude that are the positions of the corresponding radio base station.

  Based on the longitude and latitude of the wireless base station 1 and the longitude and latitude of the other wireless base station stored in the storage unit 103, the distance measuring unit 152 determines whether the wireless base station 1 and the other wireless base station Measure the distance between.

  Based on the distance between the radio base station 1 and the surrounding radio base stations measured by the distance measurement unit 152, the pre-occlusion start notification transmission processing unit 154 determines that the distance between the radio base stations 1 is a predetermined threshold value. The base station IDs of other radio base stations to be described below are specified. Here, the pre-occlusion start notification transmission processing unit 154 specifies the base station IDs of the radio base stations 2A to 2F as peripheral radio base stations whose distance from the radio base station 1 is equal to or less than a predetermined threshold. .

  Next, when the pre-blocking process is requested, the pre-blocking start notification transmission processing unit 154 generates a pre-blocking start notification indicating that the radio base station 1 starts pre-blocking. Specifically, the pre-occlusion start notification transmission processing unit 154 sets a transmission power decrease rate indicating the amount of decrease in transmission power per unit time and a pre-occlusion start time, and supports the specified base station ID. The pre-blocking start notification is generated with the wireless base stations 2A to 2F to be set as destinations. Here, the start time of pre-blocking is a time obtained by adding a predetermined time to the time when pre-blocking is requested by a network administrator or the like.

  FIG. 5 is a diagram illustrating an example of a pre-occlusion start notification. The pre-blocking start notification shown in FIG. 5 includes the base station ID of the radio base station that is the transmission source of the pre-blocking start notification (here, the ID of the radio base station 1) and the base station ID of the radio base station that is the destination (here The ID of the radio base stations 2A to 2F), the transmission power decrease rate at the time of pre-blocking, and the start time of pre-blocking.

  Further, the pre-occlusion start notification transmission processing unit 154 outputs the generated pre-occlusion start notification to the wired communication unit 104. The wired communication unit 104 transmits a pre-blocking start notification to the radio base stations 2A to 2F via the base station control device 6.

  When the set pre-blocking start time arrives, the transmission power reduction processing unit 156 reduces the transmission power from the antenna 108 according to the set transmission power reduction rate, and sends a new call from the wireless terminal 5. Do not accept.

  The existing call absence notification transmission processing unit 158 determines whether or not there is an existing call in the radio base station 1. For example, when the communication between the wireless terminal 5 and the wireless base station 1 is continuing, in other words, when there is an existing call, the wireless base station 1 reduces the transmission power according to the transmission power reduction rate. Thereafter, the wireless terminal 5 cannot communicate with the wireless base station 1 and attempts to perform handover to the wireless base station 2A or the like.

  If there is no existing call, the existing call absence notification transmission processing unit 158 generates an existing call absence notification. Specifically, the existing call absence notification transmission processing unit 158 sets a time (power stop time) at which the transmission power becomes zero in the radio base station 1, and is specified by the pre-blocking start notification transmission processing unit 154. An existing call non-existence notification in which the radio base stations 2A to 2F corresponding to the base station ID are set as destinations is generated. The power stop time is a time obtained by adding a predetermined time to the time when the wireless base station 1 determines that there is no existing call.

  FIG. 6 is a diagram illustrating an example of an existing call absence notification. The existing call absence notification shown in FIG. 6 includes the base station ID of the wireless base station that is the transmission source of the existing call absence notification (here, the ID of the wireless base station 1) and the base station ID of the wireless base station that is the destination. (Here, IDs of the radio base stations 2A to 2F) and the power stop time.

  Further, the existing call absence notification transmission processing unit 158 outputs the generated existing call absence notification to the wired communication unit 104. The wired communication unit 104 transmits the existing call absence notification to the radio base stations 2A to 2F via the base station control device 6.

  Thereafter, when the set power stop time arrives, the transmission power reduction processing unit 156 performs control to reduce the transmission power from the antenna 108 to zero.

  FIG. 7 is a functional block configuration diagram of the control unit 102 in the radio base stations 2A to 2F. As illustrated in FIG. 7, the control unit 102 in the radio base stations 2A to 2F includes a pre-blocking start notification reception processing unit 162, a direction specifying unit 164, a transmission power increase processing unit 166, and an existing call absence notification reception processing unit 168. including.

  The pre-blocking start notification reception processing unit 162 receives the pre-blocking start notification from the radio base station 1 via the base station control device 6 and the wired communication unit 104.

  The direction specifying unit 164 specifies the direction of the radio base station 1 that is the transmission source of the pre-blocking start notification.

  Specifically, in the storage unit 103, as with the storage unit 103 in the wireless base station 1, the longitude and latitude of any one of the wireless base stations 2A to 2F that are its own wireless base stations are stored. Further, the storage unit 103 stores position information of other radio base stations.

  The direction specifying unit 164 extracts the transmission source base station ID in the pre-blocking start notification, and includes the extracted transmission base station ID among the position information of other radio base stations stored in the storage unit 103. Identify information. Furthermore, the direction specifying unit 164 includes the longitude and latitude in the specified position information, in other words, the longitude and latitude of the radio base station 1 that is the transmission source of the pre-occlusion start notification, and the self stored in the storage unit 103. The direction of the radio base station 1 is specified based on the longitude and latitude of the radio base station.

  The transmission power increase processing unit 166 sets an increase amount of transmission power per unit time (transmission power increase rate) based on the transmission power decrease rate in the pre-blocking start notification. Specifically, the transmission power increase processing unit 166 matches the increase amount of the transmission power per unit time with the absolute value of the decrease amount of the transmission power per unit time indicated by the transmission power decrease rate.

  Furthermore, when the pre-blocking start time in the pre-blocking start notification arrives, the transmission power increase processing unit 166 increases the transmission power from the antenna 108 according to the set transmission power increase rate. At this time, the transmission power increase processing unit 166 increases only the transmission power directed to the sector in the direction specified by the direction specifying unit 164 among the sectors configuring any of the cells 4A to 4F.

  The existing call absence notification reception processing unit 168 receives the existing call absence notification from the radio base station 1 via the base station control device 6 and the wired communication unit 104.

  Thereafter, when the power stop time in the existing call absence notification arrives, the transmission power reduction processing unit 156 performs control to stop the increase in transmission power from the antenna 108 and maintain it at a predetermined value. Here, the predetermined value is a value such that the cells 4A to 4F of the radio base stations 2A to 2F have a size including the radio base station 1.

(2) Operation of Radio Communication System Next, the operation of the radio communication system 10 will be described. FIG. 8 is a flowchart showing the operation of the wireless communication system 10.

  In step S100, the control unit 102 in the radio base station 1 measures the distance between the radio base station 1 and another radio base station.

  When the pre-blocking process is requested in step S101, the control unit 102 in the wireless base station 1 includes the transmission power reduction rate and the pre-blocking start time, and the distance from the wireless base station 1 is a predetermined threshold value. A pre-occlusion start notification is generated with the following radio base stations 2A to 2F as destinations.

  In step S <b> 102, the control unit 102 in the radio base station 1 transmits a pre-blocking start notification to the base station control device 6. The base station control device 6 receives the pre-blocking start notification from the radio base station 1. Furthermore, in step S103, the base station control device 6 transmits a pre-blocking start notification to the radio base stations 2A to 2F. The control units 102 in the radio base stations 2A to 2F receive the pre-blocking start notification from the base station control device 6.

  In step S104, the control unit 102 in the radio base stations 2A to 2F identifies the direction of the radio base station 1.

  Thereafter, in step S105, when the set pre-blocking start time arrives, the control unit 102 in the radio base station 1 reduces the transmission power from the antenna 108 according to the set transmission power reduction rate, A new call from the terminal 5 is not accepted.

  On the other hand, in step S106, the control unit 102 in the radio base stations 2A to 2F identifies a sector in a direction that matches the direction of the identified radio base station 1 as a sector whose transmission power is to be increased. Further, the control unit 102 in the radio base stations 2A to 2F sets the transmission power increase rate according to the transmission power decrease rate included in the received pre-blocking start notification. Further, when the pre-blocking start time included in the received pre-blocking start notification arrives, the control unit 102 in the radio base stations 2A to 2F increases the transmission power from the antenna 108 according to the set transmission power decrease rate. Reduce.

  In step S <b> 107, the control unit 102 in the radio base station 1 determines whether there is an existing call for the radio base station 1. If there is an existing call, the decrease in transmission power at the radio base station 1 in step S105 and the increase in transmission power at the radio base stations 2A to 2F in step S106 are continued.

  When communication between the wireless terminal 5 and the wireless base station 1 is continuing, in other words, when there is an existing call, if the wireless base station 1 decreases the transmission power according to the transmission power decrease rate, then The wireless terminal 5 can no longer communicate with the wireless base station 1, and tries to perform handover to the wireless base station 2A or the like. Therefore, if the decrease in the transmission power in the radio base station 1 and the increase in the transmission power in the neighboring radio base stations 2A to 2F are continued, the existing call no longer exists in the radio base station 1.

  On the other hand, when there is no existing call, the control unit 102 in the radio base station 1 generates an existing call non-existence notification including the power stop time and setting the radio base stations 2A to 2F as destinations.

  In step S <b> 108, the control unit 102 in the radio base station 1 transmits an existing call absence notification to the base station control device 6. The base station control device 6 receives the existing call absence notification from the radio base station 1. Further, in step S109, the base station control device 6 transmits an existing call absence notification to the radio base stations 2A to 2F. The control unit 102 in the radio base stations 2A to 2F receives the existing call absence notification from the base station control device 6.

  Thereafter, in step S110, when the set power stop time arrives, the control unit 102 in the radio base station 1 performs control to reduce the transmission power from the antenna 108 to zero.

  On the other hand, in step S111, the control unit 102 in the radio base stations 2A to 2F stops the increase in the transmission power from the antenna 108 when the power stop time included in the received existing call non-existence notification has arrived. To maintain the control.

(3) Operation / Effect In the radio communication system 10 according to the present embodiment, the radio base station 1 that is the target of pre-occlusion reduces the transmission power, while the radio base stations 2A to 2F around the radio base station 1 Increase transmission power.

  FIG. 9 is an overall schematic configuration diagram of the wireless communication system 10 during the pre-blocking process. When FIG. 9 is compared with FIG. 1, the cell 3 which is the communication area of the radio base station 1 is narrowed, while the cells 4A to 4F which are the communication areas of the radio base stations 2A to 2F are widened and communication is impossible. It is prevented that an area is generated and a new call cannot be accepted.

  Further, since the cells 4A to 4F which are communication areas of the radio base stations 2A to 2F are widened, a new call from the radio terminal 5 existing in the cell 3 of the radio base station 1 before the pre-blocking process is Even if accepted by the stations 2A to 2F, the quality in subsequent communications is maintained.

  Also, the absolute value of the rate of decrease in transmission power at the radio base station 1 and the rate of increase in transmission power at the radio base stations 2A to 2F are equal. The start timing is synchronized with the decrease in the transmission power in the radio base station 1 and the increase in the transmission power in the radio base stations 2A to 2F. Further, the transmission power of the radio base station 1 gradually decreases, while the transmission power of the radio base stations 2A to 2F gradually increases according to the degree of decrease in the transmission power of the radio base station 1.

  Therefore, the wireless terminal 5 (see FIGS. 1 and 9) that exists in the cell 3 of the wireless base station 1 before the pre-blocking process and exists outside the cell 3 of the wireless base station 1 during the pre-blocking process is During the pre-blocking process, communication can be continued by switching the connection destination from the radio base station 1 to any of the radio base stations 2A to 2F by handover, and the forced disconnection of the existing call is prevented, and the pre-blocking process is always performed. To be done.

  In addition, the radio base station 1 communicates by increasing the transmission power in the radio base stations 2A to 2F that are close to the radio base station, in other words, in areas that are out of the cell 3 of the radio base station 1 in the pre-blocking process. A pre-blocking start notification can be transmitted only to the radio base stations 2A to 2F that can be used as areas, and an increase in transmission power can be promoted. Therefore, it is possible to suppress an increase in processing load due to transmission of unnecessary pre-occlusion start notifications and unnecessary increase in transmission power.

  In addition, the radio base stations 2A to 2F specify the direction of the radio base station 1, increase only the transmission power toward the sector in the direction, and do not increase the transmission power in other directions. For this reason, when the cells 4A to 4F of the radio base stations 2A to 2F are enlarged in a perfect circle, the area overlapping with the cells of the adjacent radio base stations is widened, and the interference is prevented from increasing.

  In addition, when there is no existing call to the own radio base station, the radio base station 1 transmits existing call non-existence notifications to the radio base stations 2A to 2F. Further, at the same timing, the radio base station 1 sets the transmission power to zero, and the radio base stations 2A to 2F stop the increase control of the transmission power and maintain the transmission power at a predetermined value. Therefore, the transmission power of the radio base stations 2A to 2F continues to increase, and as a result, the interference is prevented from increasing.

(4) Other Embodiments As described above, the present invention has been described according to the first embodiment. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  In the first embodiment described above, the radio base station 1 transmits the pre-blocking start notification and the existing call non-existence notification to the radio base stations 2A to 2F via the base station control device 6, but the base station control device You may transmit to radio base station 2A thru | or 2F directly, without going through.

  In the first embodiment described above, the case where the radio base station 1 to be preoccluded decreases the transmission power and the radio base stations 2A to 2F located around the radio base station 1 increase the transmission power has been described. The present invention can be similarly applied to the case where any one of the radio base stations 2A to 2F is subjected to pre-occlusion and decreases the transmission power, and the radio base station 1 increases the transmission power.

  In this case, the control unit 102 in the radio base stations 2A to 2F has the functional block configuration shown in FIG. 2, and the control unit 102 in the radio base station 1 has the functional block configuration shown in FIG.

  Thus, it should be understood that the present invention includes various embodiments and the like not described herein. Therefore, the present invention is limited only by the invention specifying matters in the scope of claims reasonable from this disclosure.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to the drawings. Specifically, (1) the configuration of the wireless communication system, (2) the operation of the wireless communication system, (3) the operation and effect, and (4) other embodiments will be described. In the description of the drawings in the second embodiment below, the same or similar parts are denoted by the same or similar reference numerals.

(1) Configuration of Radio Communication System (1.1) Overall Schematic Configuration of Radio Communication System FIG. 10 is an overall schematic configuration diagram of a radio communication system 10 according to the second embodiment of the present invention. The radio communication system 1 shown in FIG. 10 is based on, for example, LTE Release 9 which is a 3.9th generation (3.9G) mobile phone system or LTE-Advanced which is positioned as a 4th generation (4G) mobile phone system. It has a configuration.

  As shown in FIG. 10, the radio communication system 10 includes a base station control device 6 as a network device and radio base stations 1, 2A to 2S. The base station control device 6 is connected to the radio base stations 1, 2A to 2S via a network (not shown), and performs an apparatus such as an MME (Mobility Management Entity) that performs various controls on the upper level of the radio base stations 1, 2A to 2S. It is.

  In the present embodiment, the radio base stations 1, 2A to 2S are divided into four groups by the grouping process. In this case, the grouping process is performed so that two adjacent radio base stations belong to different groups. Here, “adjacent” is defined as follows. That is, the radio base stations 1, 2 </ b> A to 2 </ b> S in the radio communication system 1 are connected to each other by the link 200. At this time, the link 200 is set so as not to cross another link 200. Here, when the two links 200 intersect, it is preferable to avoid the intersection by preferentially setting the link 200 with a short distance. In other words, the shorter the distance between the radio base stations, the more preferably the link 200 is set between the radio base stations. In the state where the link 200 is set in this way, the two radio base stations located at both ends of one link 200 are adjacent to each other.

  According to the so-called four-color theorem, if the radio base stations 1, 2A to 2S are divided into at least four groups, two adjacent radio base stations can belong to different groups. Therefore, in this embodiment, the radio base stations 1, 2A to 2S in the radio communication system 10 are divided into four groups in order to satisfy the condition that two adjacent radio base stations belong to different groups.

  In FIG. 10, the radio base stations 1, 2A to 2S are the first group to which the radio base stations 2D, 2F, 2J, 2L, 2R corresponding to black color belong, the radio base stations 1, 2G, 2K, corresponding to white color, 2N, 2Q to which the second group belongs, radio base stations 2B, 2H, 2M, 2O, 2S corresponding to the rising stripe pattern, radio base stations 2A, 2C, corresponding to the falling stripe pattern It is divided into a fourth group to which 2E, 2I and 2P belong.

  By such grouping, two adjacent radio base stations belong to different groups. For example, when paying attention to the radio base station 1 belonging to the second group, if the radio base stations 2A, 2B, 2C, 2D, 2E, and 2F adjacent to the radio base station 1 are confirmed, the radio base station 2A is the fourth group, radio base station 2B is the third group, radio base station 2C is the fourth group, radio base station 2D is the first group, radio base station 2E is the fourth group, and radio base station 2F is the first group These are all different from the second group to which the radio base station 1 belongs.

  In the present embodiment, when the base station controller 6 performs an initial grouping process and then a radio base station is added to the radio communication system 10 or when a radio base station is excluded from the radio communication system 10 In this case, the radio base stations 1, 2A to 2S perform the grouping process (regrouping process) again.

(1.2) Configuration of Base Station Control Device FIG. 11 is a configuration diagram of the base station control device 6. As illustrated in FIG. 11, the base station control device 6 includes a control unit 212, a storage unit 213, and a wired communication unit 214.

  The control unit 212 is configured by a CPU, for example, and controls various functions provided in the base station control device 6. The storage unit 213 is configured by a memory, for example, and stores various types of information used for control in the base station control device 6. The wired communication unit 214 transmits and receives data to and from the radio base stations 1 and 2A to 2S via a network (not shown). In communication between the base station controller 6 and the radio base stations 1, 2A to 2S, for example, an S1 connection as a logical communication path is established in a network (not shown).

  The control unit 212 includes a base station information acquisition unit 252 and a grouping processing unit 254.

  The base station information acquisition unit 252 includes the longitude and latitude of the radio base stations 1, 2A to 2S for each of the radio base stations 1, 2A to 2S, and the base station ID that is identification information of the radio base stations 1, 2A to 2S. Get location information including. The location information is transmitted from the radio base stations 1, 2A to 2S, for example. In this case, the base station information acquisition unit 252 inputs position information from the radio base stations 1, 2 </ b> A to 2 </ b> S received by the wired communication unit 214. Alternatively, the position information is stored in the storage unit 213 in advance. In this case, the base station information acquisition unit 252 reads position information from the storage unit 213.

  Further, the base station information acquisition unit 252 acquires operating state information of the radio base stations 1, 2A to 2S for each of the radio base stations 1, 2A to 2S. The operating state information is information indicating whether the corresponding radio base stations 1, 2A to 2S are operating or are stopped due to a failure or the like. This operating state information is transmitted from, for example, the radio base stations 1, 2A to 2S. In this case, the base station information acquisition unit 252 inputs the operating state information received by the wired communication unit 214. Alternatively, the operating state information is stored in the storage unit 213 in advance. In this case, the base station information acquisition unit 252 reads the operating state information from the storage unit 213.

  The grouping processing unit 254 performs an initial grouping process based on the position information and operation state information for each of the radio base stations 1, 2 </ b> A to 2 </ b> S acquired by the base station information acquisition unit 252.

  Specifically, the grouping processing unit 254 sets a radio base station indicating that the corresponding operation information state is operating among the radio base stations in the radio communication system 10 as a node, A plane graph in which a link connecting two wireless base stations is set is created. Here, when setting the link, the grouping processing unit 254 identifies the positions of the radio base stations 1, 2A to 2S based on the position information of the radio base stations 1, 2A to 2S set as nodes. Then, the link is set so that the link does not intersect.

  Next, the grouping processing unit 254 includes, for each radio base station set as a node, the base station ID of the radio base station as a reference base station ID, and the bases of other radio base stations adjacent to the radio base station Neighboring base station information including the station ID as the neighboring base station ID is generated. The generated adjacent base station information is stored in the storage unit 213. FIG. 12 is a diagram illustrating an example of adjacent base station information.

  Next, for each radio base station set as a node, the grouping processing unit 254 uses the vertex coloring method so that two adjacent radio base stations belong to different groups, and uses the first group to the fourth group. Into four groups. Here, each of the first to fourth groups is associated with a group ID as identification information. In addition, the first to fourth groups are associated with different transmission time reduction time zones.

  Next, the grouping processing unit 254 generates grouping information for each radio base station set as a node. Specifically, the grouping processing unit 254 includes, for each wireless base station, adjacent base station information corresponding to the wireless base station, that is, an adjacent base station that includes the base station ID of the wireless base station as a reference base station ID. Information is read from the storage unit 213. Next, the grouping processing unit 254 adds the group ID corresponding to the group to which the radio base station specified by the reference base station ID belongs to the reference base station ID in the read adjacent base station information, and the transmission power reduction Add time zone. Further, the grouping processing unit 254 includes the group ID corresponding to the group to which the radio base station specified by the neighboring base station ID belongs, and the transmission power reduction time, in the neighboring base station ID in the read neighboring base station information. Add a band. FIG. 13 is a diagram illustrating an example of grouping information.

  In this way, after generating the grouping information for each radio base station set as a node, the grouping processing unit 254 is identified for each grouping information by the reference base station ID in the grouping information. The transmission is performed via the wired communication unit 214 with the wireless base station as the transmission destination.

(1.3) Configuration of Radio Base Station FIG. 14 is a functional block configuration diagram of the control unit 102 in the radio base station 1. As illustrated in FIG. 14, the control unit 102 includes a grouping information acquisition unit 172, a transmission power control unit 174, and a regrouping processing unit 176. The overall configuration of the radio base station 1 is the same as that shown in FIG. The overall configuration of the radio base stations 2A to 2S is the same as that in FIG. 2, and the configuration of the control unit 102 of the radio base stations 2A to 2S is the same as that in FIG.

  The grouping information acquisition unit 172 acquires grouping information from the base station control device 6 via a network and wired communication unit 104 (not shown). Further, the grouping information acquisition unit 172 stores the acquired grouping information in the storage unit 103.

  The transmission power control unit 174 reads the grouping information stored in the storage unit 103. Further, the transmission power control unit 174 generates a pre-blocking start notification including the transmission power decrease time period in the read grouping information. Next, the transmission power control unit 174 transmits a pre-blocking start notification to another wireless base station specified by the adjacent base station ID in the grouping information via the wired communication unit 104 and a network (not shown). . Furthermore, when the transmission power reduction time zone comes, the transmission power control unit 174 controls the wireless communication unit 106 to reduce the transmission power. The specific processing for the transmission power reduction is the same as the processing in the transmission power reduction processing unit 156 in the first embodiment.

  Here, the decrease in transmission power includes a case where transmission power stops. In the radio base stations belonging to the same group, the transmission power reduction time period is the same. Therefore, the radio base stations belonging to the same group reduce the transmission power in the same transmission power reduction time zone. Moreover, the transmission power reduction time zone corresponding to each group is different. Furthermore, two adjacent radio base stations belong to different groups. Therefore, two adjacent radio base stations do not reduce transmission power at the same time.

  On the other hand, when the transmission power control unit 174 receives a pre-blocking start notification from another adjacent radio base station via the network and the wired communication unit 104 (not shown), the transmission power control unit 174 includes the transmission included in the pre-blocking start notification. When the power reduction time zone comes, the wireless communication unit 106 is controlled to increase the transmission power. The specific processing for increasing the transmission power is the same as the processing in the transmission power increase processing unit 166 in the first embodiment.

  When a radio base station is added to the radio communication system 10 or when a radio base station is excluded from the radio communication system 10, the regroup processing unit 176 performs a regrouping process (regrouping process). )I do.

  Specifically, the regroup processing unit 176 identifies another radio base station adjacent to the own radio base station based on the adjacent base station ID in the grouping information. Next, the regrouping processing unit 176 sends the group ID (affiliation group ID) of the group to which the own radio base station belongs to the identified other adjacent radio base stations via the wired communication unit 104 and a network (not shown). ). Further, the regrouping processing unit 176 receives a group ID (affiliation group ID) of a group to which the other adjacent radio base station belongs from another adjacent radio base station via the network and the wired communication unit 104 (not shown). Receive. In each radio base station, the group ID of the group to which the radio base station belongs is exchanged between two adjacent radio base stations by the regrouping processing unit 176 in the control unit 102 performing the above-described processing. Will be.

  Next, the regrouping processing unit 176 is adjacent based on group IDs corresponding to all adjacent base station IDs in the grouping information and belonging group IDs from all adjacent other radio base stations. It is determined whether or not the group to which another radio base station belongs has changed. Specifically, the regroup processing unit 176, for each other adjacent radio base station, the group ID corresponding to the other adjacent radio base station in the grouping information and the other adjacent radio base station The group IDs from the stations are compared, and if they match, it is determined that there is no change in the group to which the other adjacent radio base station belongs, and if not, the other other radio base station It is determined that a change has occurred in the group to which.

  When a change is made to a group to which another adjacent radio base station belongs, the regrouping processing unit 176 further includes a group ID that is a group ID of the group after the change, and a group ID of the group to which the own radio base station belongs. Compare If the two group IDs match, the own radio base station and other adjacent radio base stations belong to the same group. In this case, the regrouping processing unit 176 changes the group to which the own radio base station belongs. Further, the regroup processing unit 176 transmits the group ID of a new group to which the own radio base station belongs to another adjacent radio base station via the wired communication unit 104 and a network (not shown).

  By performing the above-described processing until the groups to which two adjacent radio base stations belong become different, each radio base station performs autonomous regrouping.

(2) Operation of Radio Communication System Next, the operation of the radio communication system 10 will be described. FIG. 15 is a sequence diagram illustrating an initial grouping operation of the wireless communication system 10.

  In step S200, the base station control device 6 acquires position information for each of the radio base stations 1, 2A to 2S. Furthermore, the base station control device 6 acquires operating state information for each of the radio base stations 1, 2A to 2S.

  In step S201, the base station control device 6 performs an initial grouping process for the radio base stations 1, 2A to 2S based on the acquired position information and operation state information for each of the radio base stations 1, 2A to 2S. In the initial grouping process, the base station control device 6 generates grouping information for each of the radio base stations 1, 2A to 2S.

  In step S202, the base station control device 6 transmits the grouping information to the radio base stations 1, 2A to 2S. The radio base stations 1, 2 </ b> A to 2 </ b> S receive the grouping information from the base station control device 6.

  After that, in step S203, when the transmission power reduction time zone in the grouping information comes, the radio base stations 1, 2A to 2S perform control to reduce transmission power or control to increase transmission power.

  FIG. 16 is a flowchart showing the regrouping operation of the radio base stations 1, 2A to 2S.

  In step S300, the radio base stations 1, 2A to 2S transmit the belonging group ID corresponding to the own radio base station to other adjacent radio base stations. Further, in step S301, the radio base stations 1, 2A to 2S receive the belonging group ID corresponding to the adjacent radio base station from other adjacent radio base stations.

  In step S302, the radio base stations 1, 2A to 2S determine whether or not the group to which another adjacent radio base station belongs has changed.

  When the group to which another adjacent radio base station belongs has not changed, the series of operations ends. On the other hand, when the group to which another adjacent radio base station belongs has changed, in step S303, the radio base stations 1, 2A to 2S perform a regrouping process.

  Further, in step S304, the radio base stations 1, 2A to 2S make other radio base stations adjacent to the group ID (affiliation group ID) of the group to which the own radio base station newly belongs by the regrouping process. Send to.

(3) Operation / Effect In the wireless communication system 10 according to the present embodiment, two adjacent wireless base stations belong to different groups, and the time zone in which the transmission power decreases in the wireless base station differs for each group. Yes.

  In order to realize such grouping, the base station controller 6 at the higher level of the radio base stations 1, 2A to 2S is divided into four groups of radio base stations 1, 2A to 2S by the so-called four-color theorem. Then, grouping is performed so that two adjacent radio base stations belong to different groups.

  As a result, when the transmission power of a plurality of radio base stations is simultaneously stopped or the transmission power of the radio base station is reduced from the viewpoint of energy saving in order to reduce the maintenance work time, As a result of simultaneously stopping the transmission power of the two radio base stations, a wide dead zone does not occur, and it is possible to reduce the transmission power of the radio base station while suppressing deterioration of the quality of the communication service Become.

  In the radio communication system 10 according to the present embodiment, when a radio base station is added to the radio communication system 10 or when a radio base station is excluded from the radio communication system 10, the radio base station 1 2A to 2S exchange the group ID of the group to which the own radio base station belongs with another adjacent radio base station by inter-base station communication. As a result, the radio base stations 1, 2A to 2S can identify the group to which the other adjacent radio base station belongs, and change their own radio base station according to the change of the group to which the other adjacent radio base station belongs. A regrouping process of changing the group to which the station belongs can be performed. Further, the radio base stations 1, 2A to 2S transmit the group ID of the group to which the own radio base station newly belongs to other adjacent radio base stations. As a result, the radio base stations 1, 2A to 2S notify other adjacent radio base stations of the group to which the own radio base station newly belongs, and regroup in the adjacent other radio base stations. Processing can be performed.

(4) Other Embodiments As described above, the present invention has been described according to the embodiment. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  In the above-described embodiment, in order to satisfy the condition that two adjacent radio base stations belong to different groups, the radio base stations 1, 2A to 2S in the radio communication system 10 are divided into four groups. It may be divided into five or more groups. For example, when the radio base stations 1, 2 </ b> A to 2 </ b> S in the radio communication system 10 are divided into five groups, when a radio base station is added to the radio communication system 10, In the regrouping process when a station is excluded, it is possible to limit the range of radio base stations whose group is changed.

  In the above-described embodiment, the wireless communication system 10 has a configuration based on LTE Release 9 or LTE-Advanced, but may have a configuration based on other communication standards.

  Thus, it should be understood that the present invention includes various embodiments and the like not described herein. Therefore, the present invention is limited only by the invention specifying matters in the scope of claims reasonable from this disclosure.

  The radio communication system, radio base station, network device, and blockage control method of the present invention prevent the deterioration of the quality of communication services, and are useful as radio communication systems and the like.

  DESCRIPTION OF SYMBOLS 1 ... Wireless base station, 2A-2S ... Wireless base station, 3 ... Cell, 4A-4F ... Cell, 5 ... Wireless terminal, 6 ... Base station control apparatus, 10 ... Wireless communication system, 102 ... Control part, 103 ... Memory | storage 104 ... Wired communication unit 106 ... Wireless communication unit 108 ... Antenna 152 ... Distance measuring unit 154 ... Pre-blocking start notification transmission processing unit 156 ... Transmission power reduction processing unit 158 ... Existing call non-existence notification transmission Processing unit 162 ... Pre-occlusion start notification reception processing unit, 164 ... Direction specifying unit, 166 ... Transmission power increase processing unit, 168 ... Existing call absence notification reception processing unit, 172 ... Grouping information acquisition unit, 174 ... Transmission power Control unit, 176 ... regroup processing unit, 252 ... base station information acquisition unit, 254 ... grouping processing unit

Claims (14)

A wireless communication system including a plurality of wireless base stations,
The first radio base station
A storage unit for storing information of the second radio base station;
Pre-occlusion start notification indicating that pre-occlusion is to be started for the second radio base station specified based on information of the second radio base station stored in the storage unit when pre-occlusion is started A pre-occlusion start notification transmission unit for transmitting
A transmission power reduction processing unit for reducing transmission power,
The second radio base station is
A pre-occlusion start notification receiving unit for receiving the pre-occlusion start notification;
A wireless communication system comprising: a transmission power increase processing unit that increases transmission power when the pre-blocking start notification is received by the pre-blocking start notification receiving unit. The transmission power reduction processing unit reduces the transmission power by a predetermined amount within a predetermined time,
The wireless communication system according to claim 1, wherein the transmission power increase processing unit increases the transmission power by the predetermined amount within the predetermined time. The first radio base station includes a distance measuring unit that measures a distance between the own radio base station and the second radio base station,
The said pre-occlusion start notification transmission part transmits the said pre-occlusion start notice with respect to the said 2nd wireless base station from which the distance measured by the said distance measurement part becomes below a predetermined threshold value. Wireless communication system. The second radio base station includes a direction specifying unit that specifies the direction of the first radio base station,
4. The radio communication system according to claim 1, wherein the transmission power increase processing unit increases transmission power in a direction of the first radio base station specified by the direction specifying unit. 5. The first radio base station transmits an existing call non-existence notification indicating that there is no existing call to the second radio base station when there is no existing call in the own radio base station. A notification transmitter,
The second radio base station includes an existing call absence notification receiving unit that receives the existing call absence notification,
5. The radio according to claim 1, wherein the transmission power increase processing unit stops the increase in the transmission power when the existing call absence notification receiving unit receives the existing call absence notification. Communications system. A base station controller for connecting and controlling the first radio base station and the second radio base station;
The wireless communication system according to any one of claims 1 to 5, wherein the pre-blocking start notification transmission unit transmits the pre-blocking start notification to the second wireless base station via the base station control device. The plurality of radio base stations belong to different groups;
The radio communication system according to claim 1, wherein a time period during which transmission power decreases in the radio base station differs for each group. A network device in a higher rank of the plurality of radio base stations,
The wireless communication system according to claim 7, wherein the network device includes a grouping processing unit that performs grouping to divide the plurality of wireless base stations into four or more groups according to a predetermined condition.   The radio base station uses inter-base station communication when another radio base station is added to the radio communication system, or when another radio base station is excluded from the radio communication system, The wireless communication system according to claim 7 or 8, further comprising a regrouping processing unit that performs a regrouping process for dividing a plurality of wireless base stations into groups again. A radio base station constituting a radio communication system,
A storage unit for storing information of other radio base stations located around the own radio base station;
Pre-occlusion start notification indicating that pre-occlusion is to be started for the other radio base station specified based on the information of the other radio base station stored in the storage unit when pre-occlusion is started A pre-occlusion start notification transmission unit for transmitting
A radio base station comprising: a transmission power reduction processing unit that reduces transmission power. A radio base station constituting a radio communication system,
A pre-blocking start notification receiving unit for receiving a pre-blocking start notification indicating that pre-blocking is started in the other wireless base station from another wireless base station;
A radio base station comprising: a transmission power increase processing unit that increases transmission power when the pre-blocking start notification is received by the pre-blocking start notification receiving unit. It is divided into a plurality of groups together with other radio base stations so that two adjacent radio base stations belong to different groups.
The radio base station according to claim 10 or 11, further comprising: a transmission power control unit that reduces transmission power in the same time zone as other radio base stations belonging to the same group as the own radio base station. A network device above a plurality of radio base stations constituting a radio communication system,
A grouping processing unit that performs grouping to divide the plurality of radio base stations into four or more groups according to a predetermined condition,
A network device in which a time zone in which transmission power decreases in the radio base station differs for each group. A block control method in a radio communication system including a plurality of radio base stations,
When the first radio base station starts pre-blocking, the first radio base station starts pre-blocking with respect to the second radio base station specified based on the information of the second radio base station stored in the storage unit. Sending a pre-occlusion start notification indicating;
The first radio base station reducing transmission power;
The second radio base station receiving the pre-occlusion start notification;
The second radio base station includes a step of increasing transmission power when the pre-blocking start notification is received.

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