JP2011217325A - Radio communication system, radio base station and network apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce transmission power of a radio base station while suppressing deterioration in quality of communication services.SOLUTION: In a radio communication system 1, adjacent two radio base stations 100 belong to different groups and a time zone, wherein the transmission power is reduced in each radio base station 100, is different for each group. In order to achieve such grouping, a network apparatus 10 in a layer higher than the radio base stations 100 performs grouping on the respective radio base stations 100 in accordance with a genetic algorithm in such a way that adjacent two radio base stations 100 belong to different groups.

Description

  The present invention relates to a radio communication system having a plurality of radio base stations, a radio base station constituting the radio communication system, and a network apparatus in a higher rank of the radio base station.

  In a wireless communication system, when maintenance work for 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 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 1). Such a process is called a pre-occlusion process. 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.

Japanese Patent Laid-Open No. 10-209947

  However, 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, and a network device that reduce transmission power of a radio base station while suppressing deterioration in quality of communication services.

  In order to solve the above-described problems, the present invention has the following features. A first feature of the present invention is a wireless communication system (wireless communication system 1) having a plurality of wireless base stations (wireless base station 100a to wireless base station 100g). The gist is that the station is divided into groups satisfying the condition that two adjacent radio base stations belong to different groups, and the time zone in which the transmission power decreases in the radio base station 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.

  A second feature of the present invention includes a network device (network device 10) in a higher rank than the radio base station, and the network device uses the genetic algorithm to connect the plurality of radio base stations to two adjacent radio base stations. The gist of the present invention is to include a grouping processing unit (grouping processing unit 54) that performs grouping into groups that satisfy the condition that the wireless base stations belong to different groups.

  According to a third aspect of the present invention, when the radio base station is added to the radio communication system, or when another radio base station is excluded from the radio communication system, Re-grouping processing that divides the plurality of radio base stations into groups that satisfy the condition that two adjacent radio base stations belong to different groups by using the genetic algorithm again using inter-base station communication The gist of the present invention is to include a regrouping processing unit (regrouping processing unit 154) that performs the above.

  A fourth feature of the present invention is a wireless base station (wireless base station 100a to wireless base station 100g) that forms a wireless communication system (wireless communication system 1) together with other wireless base stations, and is based on a genetic algorithm, Along with other radio base stations, it is divided into groups that satisfy the condition that two adjacent radio base stations belong to different groups, and the same time as other radio base stations belonging to the same group as its own radio base station The gist is to provide a transmission power control unit (transmission power control unit 160) for reducing transmission power in the band.

  A fifth feature of the present invention is that a pre-occlusion start notification transmission unit (pre-occlusion start notification transmission unit 156) transmits a pre-occlusion start notification indicating that pre-occlusion is started to the other adjacent radio base station. It is a summary to provide.

  A sixth feature of the present invention is that a pre-occlusion start notification receiving unit (pre-occlusion start notification receiving unit that receives a pre-occlusion start notification indicating the start of pre-occlusion is transmitted by the other adjacent radio base station. 158).

  A seventh feature of the present invention is that a transmission power change stop is transmitted to transmit a transmission power change stop notification indicating start of pre-blocking indicating that the change of transmission power is to be stopped to the other adjacent radio base station. The gist is to include a notification transmission unit (transmission power change stop notification transmission unit 162).

  An eighth feature of the present invention is that transmission power for receiving a transmission power change stop notification indicating start of pre-occlusion indicating that transmission power change is to be stopped, transmitted by the other adjacent radio base station, is transmitted. The gist is to include a change stop notification receiver (transmission power change stop notification receiver 164).

  A ninth feature of the present invention is a network device (network device 10) at a higher level than a plurality of wireless base stations (wireless base station 100a to wireless base station 100g) constituting the wireless communication system (wireless communication system 1). The grouping processing unit (grouping processing unit 54) performs grouping by dividing the plurality of radio base stations into groups satisfying the condition that the two adjacent radio base stations belong to different groups by a genetic algorithm. The time zone in which the transmission power decreases in the radio base station is different for each group.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to reduce the transmission power of a wireless base station, suppressing the deterioration of the quality of a communication service.

1 is an overall schematic configuration diagram of a wireless communication system according to an embodiment of the present invention. 1 is a configuration diagram of a network device according to an embodiment of the present invention. It is a figure which shows an example of adjacent base station information. It is a figure explaining the process which divides | segments a some radio base station into three groups. It is a figure which shows an example of grouping information. It is a block diagram of the radio base station which concerns on embodiment of this invention. It is a figure which shows an example of the pre-occlusion start notification. It is a sequence diagram which shows operation | movement of the initial grouping of the radio | wireless communications system which concerns on embodiment of this invention. It is a flowchart which shows the operation | movement of the regrouping of the wireless base station which concerns on embodiment of this invention. It is a flowchart which shows the 1st operation | movement in the pre-blocking of the wireless base station which concerns on embodiment of this invention. It is a flowchart which shows the 1st operation | movement in the pre-blocking of the wireless base station which concerns on embodiment of this invention.

  Next, an 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 following embodiments, 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. 1 is an overall schematic configuration diagram of a radio communication system 1 according to an embodiment of the present invention. The wireless communication system 1 shown in FIG. 1 is based on, for example, LTE Release 9 that is a 3.9th generation (3.9G) mobile phone system or LTE-Advanced that is positioned as a 4th generation (4G) mobile phone system. It has a configuration.

  As shown in FIG. 1, the radio communication system 1 includes a network device (maintenance device) 10 and radio base stations 100a to 100g. The network apparatus 10 is an apparatus such as an MME (Mobility Management Entity) that is connected to the radio base stations 100a to 100g via a network (not shown) and performs various controls on the upper level of the radio base stations 100a to 100g. It is. In the following, when the radio base stations 100a to 100g are not distinguished, they are simply referred to as “radio base stations 100”.

  In the present embodiment, each radio base station 100 is divided into a plurality of groups by grouping processing. In this case, grouping processing is performed in which two adjacent radio base stations 100 are divided into groups that satisfy the condition that the two adjacent radio base stations belong to different groups by a genetic algorithm.

  Here, “adjacent” is defined as follows. That is, the radio base station 100 a to the radio base station 100 g in the radio communication system 1 are nodes and are connected to each other by the link 101. At this time, the link 101 is set so as not to cross the other link 101. When two links 101 intersect, it is preferable to avoid the intersection by preferentially setting the link 101 with a short distance. In other words, as the distance between the radio base stations 100 is shorter, it is preferable that the link 101 is preferentially set between the radio base stations 100. In a state where the link 101 is set in this way, the two radio base stations 100 located at both ends of the one link 101 are adjacent to each other.

  In FIG. 1, each radio base station 100 includes a radio base station 100a, a radio base station 100d, and a radio base station 100f to which the radio base station 100f belongs, corresponding to a stripe pattern with a lower right, and a radio base station with a stripe pattern with an upper right. The base station 100b is divided into a second group to which the radio base station 100e belongs, a third group to which the radio base station 100c corresponding to white color belongs, and a fourth group to which the radio base station 100g corresponding to black color belongs.

  By such grouping, two adjacent radio base stations 100 belong to different groups. For example, when focusing on the radio base station 100c belonging to the third group, the radio base station 100a, the radio base station 100b, the radio base station 100d, the radio base station 100e, and the radio base station 100f adjacent to the radio base station 100c. When the group to which the radio base station 100g belongs is confirmed, the radio base station 100a is the first group, the radio base station 100b is the second group, the radio base station 100d is the first group, the radio base station 100e is the second group, the radio base The station 100f is a first group, and the radio base station 100g is a fourth group. That is, the radio base station 100a, the radio base station 100b, the radio base station 100d, the radio base station 100e, the radio base station 100f, and the radio base station 100g all belong to a group different from the third group to which the radio base station 100c belongs. .

  In the present embodiment, when the network device 10 performs an initial grouping process and then a radio base station is added to the radio communication system 1 or when a radio base station is excluded from the radio communication system 1. Each radio base station 100 performs grouping processing (regrouping processing) again.

(1.2) Configuration of Network Device FIG. 2 is a configuration diagram of the network device 10. As illustrated in FIG. 2, the network device 10 includes a control unit 12, a storage unit 13, and a wired communication unit 14.

  The control part 12 is comprised by CPU, for example, and controls the various functions with which the network apparatus 10 is provided. The storage unit 13 is configured by a memory, for example, and stores various types of information used for control and the like in the network device 10. The wired communication unit 104 transmits and receives data to and from the radio base station 100 via a network (not shown). In communication between the network device 10 and the radio base station 100, for example, an S1 interface as a logical communication path is established in a network (not shown). In communication between the radio base stations 100, for example, an X2 interface as a logical communication path is established in a network (not shown).

  The control unit 12 includes a base station information acquisition unit 52 and a grouping processing unit 54.

  The base station information acquisition unit 52 acquires position information including the longitude and latitude of the radio base station 100 for each radio base station 100 and a base station ID that is identification information of the radio base station. The location information is transmitted from the radio base station 100, for example. In this case, the base station information acquisition unit 52 inputs position information from the radio base station 100 received by the wired communication unit 14. Alternatively, the position information is stored in advance in the storage unit 13. In this case, the base station information acquisition unit 52 reads position information from the storage unit 13.

  Further, the base station information acquisition unit 52 acquires the operating state information of the radio base station 100 for each radio base station 100. The operating state information is information indicating whether the corresponding radio base station 100 is operating or is stopped due to a failure or the like. This operating state information is transmitted from the radio base station 100, for example. In this case, the base station information acquisition unit 52 inputs operation state information received by the wired communication unit 14. Alternatively, the operating state information is stored in the storage unit 13 in advance. In this case, the base station information acquisition unit 52 reads the operating state information from the storage unit 13.

  The grouping processing unit 54 performs an initial grouping process based on the position information and operation state information for each radio base station 100 acquired by the base station information acquisition unit 52.

  Specifically, the grouping processing unit 54 sets, as a node, the radio base station 100 indicating that the corresponding operation information state is operating among the radio base stations 100 in the radio communication system 1. Then, a plane graph in which a link connecting two adjacent radio base stations 100 is set is created. Here, when setting the link, the grouping processing unit 54 specifies the position of each radio base station 100 based on the position information of each radio base station 100 set as a node, and the link does not intersect. Set the link as follows.

  The grouping processing unit 54 includes, for each radio base station 100 set as a node, the base station ID of the radio base station 100 as a reference base station ID, and other radio base stations 100 ( Hereinafter, adjacent base station information including the base station ID of the adjacent base station) is generated as the adjacent base station ID. The generated adjacent base station information is stored in the storage unit 13. FIG. 3 is a diagram illustrating an example of adjacent base station information. The grouping processing unit transmits the adjacent base station information to the radio base station 100 corresponding to the adjacent base station information via the wired communication unit 104.

  The grouping processing unit 54 performs a grouping process for each radio base station 100 set as a node by using a genetic algorithm to divide into groups satisfying the condition that two adjacent radio base stations 100 belong to different groups. .

  In the grouping process, the grouping processing unit 54 first tries to divide each radio base station 100 into three groups using a vertex coloring method. FIG. 4 is a diagram illustrating a process of dividing each radio base station 100 into three groups. In FIG. 4, the radio base station 100a, the radio base station 100d, and the radio base station 100f corresponding to the right-down stripe pattern, the radio base station 100b and the radio base station 100e corresponding to the right-up stripe pattern are included. It is divided into the second group to which it belongs, the third group to which the radio base station 100c corresponding to white and the radio base station 100g belong.

  The result of the grouping process is obtained as a list corresponding to genetic information in the genetic algorithm. This list is configured by associating a base station ID of each radio base station 100 with a group ID as identification information of a group to which the radio base station 100 belongs.

  The grouping processing unit 54 calculates an adaptation rate corresponding to the result of the grouping process. The adaptation rate indicates the ratio of the number of links belonging to different groups at both end nodes to the number of all links. The calculation formula for the adaptation rate [%] is (1−number of same-color links / number of all links) × 100. Here, the same color link means a link in which nodes at both ends belong to the same group. For example, in the example of FIG. 4, only the link 101 that connects the radio base station 100 c and the radio base station 100 g among the 12 links 101 is the same color link. Accordingly, the adaptation rate corresponding to the result of the grouping process shown in FIG. 4 is (1-1 / 12) × 100 = 91.7 [%].

  When the adaptation rate is 100 [%], the grouping processing unit 54 determines the group corresponding to the result of the grouping process as the final group.

  On the other hand, when the adaptation rate is not 100 [%], the grouping processing unit 54 tries again the process of dividing each radio base station 100 into three groups.

  Thereafter, the grouping processing unit 54 determines whether or not a predetermined time T has elapsed since the start of the process of dividing each of the first radio base stations 100 into three groups. When the predetermined time T has elapsed, the grouping processing unit 54 stops the process of dividing each radio base station 100 into three groups. The grouping processing unit 54 performs processing to divide into four groups using the vertex coloring method so that two adjacent radio base stations 100 belong to different groups. According to the so-called four-color theorem, if each radio base station 100 is divided into at least four groups, two adjacent radio base stations 100 can belong to different groups. The first to fourth groups are associated with different transmission time reduction time zones.

  The grouping processing unit 54 generates grouping information for each radio base station 100 set as a node. Specifically, the grouping processing unit 54 includes, for each radio base station 100, adjacent base station information corresponding to the radio base station 100, that is, the base station ID of the radio base station 100 as a reference base station ID. The adjacent base station information is read from the storage unit 13. The grouping processing unit 54 includes a group ID corresponding to a group to which the radio base station 100 specified by the reference base station ID belongs to the reference base station ID in the read adjacent base station information, and a transmission power reduction time zone. Is added. The grouping processing unit 54 includes a group ID corresponding to a group to which the radio base station 100 specified by the adjacent base station ID belongs, and a transmission power reduction time zone, in the adjacent base station ID in the read adjacent base station information. Is added. FIG. 5 is a diagram illustrating an example of grouping information.

  After generating the grouping information for each radio base station 100 set as a node, the grouping processing unit 54 determines the radio base station identified by the reference base station ID in the grouping information for each grouping information. Transmission is performed via the wired communication unit 104 with 100 as a transmission destination.

(1.3) Configuration of Radio Base Station FIG. 6 is a configuration diagram of the radio base station 100. As illustrated in FIG. 6, the radio base station 100 includes a control unit 102, a storage unit 103, a wired communication unit 104, a radio communication unit 106, and an antenna 108.

  The control unit 102 is configured using a CPU, for example, and controls various functions provided in the radio base station 100. The storage unit 103 is configured using, for example, a memory, and stores various types of information used for controlling the radio base station 100 and the like. The wired communication unit 104 communicates with the network device 10 and other wireless base stations 100 via a network (not shown). In communication between the radio base station 100 and another radio base station 100, for example, an X2 interface as a logical communication path is established in a network (not shown).

  The wireless communication unit 106 is configured using, for example, a radio frequency (RF) circuit, a baseband (BB) circuit, and the like, and transmits and receives a wireless signal to and from a wireless terminal (not shown) via the antenna 108. In addition, the wireless communication unit 106 performs encoding and modulation of the transmission signal and demodulation and decoding of the reception signal.

  The control unit 102 includes a grouping information acquisition unit 152, a regrouping processing unit 154, a pre-occlusion start notification transmission unit 156, a pre-occlusion start notification reception unit 158, a transmission power control unit 160, a transmission power change stop notification transmission unit 162, A transmission power change stop notification receiving unit 164 is provided.

  The grouping information acquisition unit 152 acquires grouping information from the network device 10 via a network (not shown) and the wired communication unit 104. Further, the grouping information acquisition unit 152 causes the storage unit 103 to store the acquired grouping information.

  When a radio base station is added to the radio communication system 1 or when a radio base station is excluded from the radio communication system 1, the regroup processing unit 154 performs a regrouping process (regrouping process). )I do.

  Specifically, the regroup processing unit 154 specifies another radio base station 100 (adjacent base station) adjacent to the own radio base station based on the adjacent base station ID in the grouping information. The regrouping processing unit 154 sends the group ID (group to which the own radio base station belongs to the identified adjacent base station via the wired communication unit 104 and the X2 interface or S1 interface in the network (not shown). ID).

  The regrouping processing unit 154 receives a group ID (affiliated group ID) of a group to which the adjacent base station belongs from an adjacent base station via a network (not shown) and the wired communication unit 104. In each radio base station 100, the regrouping processing unit 154 in the control unit 102 performs the above-described processing, so that the group ID of the group to which the radio base station 100 belongs between two adjacent radio base stations 100. Will be replaced.

  Next, the regrouping processing unit 154 performs the adjacent processing based on the group IDs corresponding to all adjacent base station IDs in the grouping information and the belonging group IDs from all the other adjacent wireless base stations 100. It is determined whether the group to which the base station belongs has changed. Specifically, for each adjacent base station, the regrouping processing unit 154 compares the group ID corresponding to the adjacent base station in the grouping information with the group ID from the adjacent base station, and matches the group ID. If it is determined that there is no change in the group to which the adjacent base station belongs, and if it does not match, it is determined that a change has occurred in the group to which the adjacent base station belongs.

  When the group is changed to the group to which the adjacent base station belongs, the regrouping processing unit 154 compares the group ID that is the group ID of the group after the change with the group ID of the group to which the own radio base station belongs. If the two group IDs match, the own radio base station and the adjacent base station belong to the same group. In this case, the regrouping processing unit 154 changes the group to which the own radio base station belongs. Furthermore, the regroup processing unit 154 transmits the group ID of the new group to which the own radio base station belongs to the adjacent 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 100 belong become different, each radio base station 100 autonomously performs regrouping.

  The pre-occlusion start notification transmission unit 156 reads the grouping information stored in the storage unit 103. Further, the transmission power control unit 160 starts pre-blocking indicating that the own radio base station starts pre-blocking before the transmission power reduction time zone corresponding to the reference base station ID in the read grouping information arrives. Generate a notification (preparation signal). Specifically, the pre-blocking start notification transmission unit 156 includes a transmission power decrease rate indicating the amount of decrease in transmission power per unit time, and a pre-blocking start time, and a pre-blocking setting with an adjacent base station ID as a destination. Generate a shutdown start notification. Here, the pre-occlusion start time is the start time of the transmission power reduction time zone corresponding to the reference base station ID.

  FIG. 7 is a diagram illustrating an example of a pre-occlusion start notification. The pre-blocking start notification shown in FIG. 7 includes the base station ID of the radio base station that is the transmission source of the pre-blocking start notification (here, the reference base station ID) and the base station ID of the adjacent base station that is the destination (adjacent base station ID), the transmission power decrease rate during pre-occlusion, and the start time of pre-occlusion.

  The pre-occlusion start notification transmission unit 156 outputs the generated pre-occlusion start notification to the wired communication unit 104. The wired communication unit 104 transmits a pre-occlusion start notification to the adjacent base station via the X2 interface or the S1 interface.

  When the pre-blocking start time arrives, the transmission power control unit 160 reduces the transmission power from the antenna 108 according to the set transmission power reduction rate, and does not accept a new call from the wireless terminal. .

  In the radio base stations 100 belonging to the same group, the transmission power decrease time period is the same. Therefore, the radio base stations 100 belonging to the same group reduce the transmission power in the same transmission power reduction time zone. On the other hand, the transmission power reduction time zone corresponding to each group is different. Further, two adjacent radio base stations 100 belong to different groups. Therefore, two adjacent radio base stations 100 do not simultaneously reduce transmission power.

  The transmission power control unit 160 determines whether there is an existing call to the own radio base station, in other words, whether there is a radio terminal that is continuing communication with the own radio base station. When there is an existing call, that is, when communication is continuing between the wireless terminal and the own wireless base station, the transmission power control unit 160 continues to decrease the transmission power according to the transmission power decrease rate. On the other hand, the increase in transmission power at the adjacent base station is continued. When the transmission power reduction by the transmission power control unit 160 continues according to the transmission power reduction rate, the wireless terminal can no longer communicate with its own wireless base station, and tries to perform handover to an adjacent base station. Become. Therefore, if the decrease in the transmission power at the own radio base station and the increase in the transmission power at the adjacent base station are continued, the existing call will no longer exist in the own radio base station.

  On the other hand, when there is no existing call, the transmission power control unit 160 performs control (stops) to make transmission power from the antenna 108 zero.

  When there is no existing call and when the transmission power from the antenna 108 becomes zero, the transmission power change stop notification transmission unit 162 measures the reception level (RSSI, etc.) of the signal from the adjacent base station. To do. When the reception level is equal to or higher than a predetermined threshold, the transmission power change stop notification transmission unit 162 sends a transmission power change stop notification to the adjacent base station that is a transmission source of a signal whose reception level is equal to or higher than the predetermined threshold. Generate and output to the wired communication unit 104. The wired communication unit 104 transmits a transmission power change stop notification to the adjacent base station via the X2 interface or the S1 interface.

  The pre-blocking start notification receiving unit 158 receives the pre-blocking start notification from the adjacent base station via the X2 interface or the S1 interface and the wired communication unit 104.

  The transmission power control unit 160 identifies the direction of the adjacent base station that is the transmission source of the pre-blocking start notification.

  Specifically, in the storage unit 103, the longitude and latitude of the own radio base station and the position information of the adjacent base station are stored together with the base station ID of the corresponding radio base station. The transmission power control unit 160 extracts the transmission source base station ID in the pre-blocking start notification, and the positional information including the extracted transmission source base station ID among the positional information of the adjacent base stations stored in the storage unit 103 Is identified. The transmission power control unit 160 determines the longitude and latitude in the specified position information, in other words, the longitude and latitude of the adjacent base station that is the transmission source of the pre-occlusion start notification, and the own radio base station stored in the storage unit 103. Based on the longitude and latitude of the station, the direction of the adjacent base station is specified.

  The transmission power control unit 160 sets an increase amount of transmission power per unit time (transmission power increase rate) based on the transmission power decrease rate in the received pre-blocking start notification. Specifically, the transmission power control unit 160 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.

  When the pre-blocking start time in the pre-blocking start notification arrives, the transmission power control unit 160 increases the transmission power from the antenna 108 according to the set transmission power increase rate. At this time, the transmission power control unit 160 increases only the transmission power directed to the sector in the specified direction among the sectors configured by the own radio base station.

  The transmission power change stop notification receiving unit 164 receives the transmission power change stop notification from the adjacent base station via the X2 interface or the S1 interface and the wired communication unit 104.

  When the transmission power change stop notification is received, the transmission power control unit 160 performs control to stop the increase in transmission power from the antenna 108 and maintain the increased transmission power.

The transmission power control unit 160 continues to increase the transmission power from the antenna 108 until the transmission power change stop notification reception unit 164 receives the transmission power change stop notification. When the transmission power change stop notification receiving unit 164 receives the transmission power change stop notification, the transmission power control unit 160 stops the increase of the transmission power from the antenna 108 and maintains the increased transmission power. Control.
(2) Operation of Radio Communication System Next, the operation of the radio communication system 1 will be described. FIG. 8 is a sequence diagram showing an initial grouping operation of the wireless communication system 1.

  In step S <b> 100, the network device 10 acquires location information for each radio base station 100. Furthermore, the network device 10 acquires operating state information for each wireless base station 100.

  In step S <b> 101, the network device 10 performs an initial grouping process for each radio base station 100 based on the acquired position information and operation state information for each radio base station 100. In the initial grouping process, the network device 10 generates grouping information for each radio base station 100.

  In step S <b> 102, the network device 10 transmits grouping information to the radio base station 100. The radio base station 100 receives the grouping information from the network device 10.

  Thereafter, in step S103, when the transmission power reduction time zone in the grouping information arrives, the radio base station 100 performs control to reduce the transmission power.

  FIG. 9 is a flowchart showing the regrouping operation of the radio base station 100.

  In step S200, the radio base station 100 transmits the belonging group ID corresponding to the own radio base station to the adjacent base station. Furthermore, in step S201, the radio base station 100 receives the belonging group ID corresponding to the adjacent base station from the adjacent base station.

  In step S202, the radio base station 100 determines whether the group to which the adjacent base station belongs has changed.

  If the group to which the adjacent base station belongs has not changed, the series of operations ends. On the other hand, when the group to which the adjacent base station belongs has changed, in step S203, the radio base station 100 performs a regrouping process.

  Further, in step S204, the radio base station 100 transmits the group ID (affiliation group ID) of the group to which the own radio base station newly belongs by the regrouping process to the adjacent base station.

  FIG. 10 is a flowchart showing an operation of the radio base station 100 when the radio base station 100 is a target of pre-occlusion.

  In step S300, the radio base station 100 transmits a blocking start notification to the adjacent base station.

  In step S301, the radio base station 100 determines whether there is an existing call for the own radio base station.

  When there is an existing call for the own radio base station, in step S302, the radio base station 100 reduces the transmission power at the set transmission power reduction rate. Thereafter, the operations after the determination of whether or not there is an existing call in step S301 are repeated.

  On the other hand, when there is no existing call to the own radio base station, in step S303, the radio base station 100 performs control (stops) to make the transmission power zero.

In step S304, the radio base station 100 measures the reception level of the signal from the adjacent base station, and determines whether or not the reception level is equal to or higher than a predetermined threshold value.

  When the reception level is equal to or higher than the predetermined threshold, in step S305, the radio base station 100 transmits a transmission power change stop notification to the adjacent base station.

  FIG. 11 is a flowchart illustrating an operation of the radio base station 100 when another radio base station 100 (adjacent base station) adjacent to the radio base station 100 is a target for pre-occlusion.

  In step S400, the radio base station 100 receives a blocking start notification from an adjacent base station.

  In step S401, the radio base station 100 increases the transmission power at the set transmission power increase rate based on the received blocking start notification.

  In step S402, the radio base station 100 receives a transmission power change stop notification from an adjacent base station.

In step S403, the radio base station 100 stops the increase in transmission power according to the transmission power change stop notification.
(3) Operation / Effect In the wireless communication system 1 according to the embodiment of the present invention, two adjacent wireless base stations 100 belong to different groups, and the time zone in which the transmission power decreases in the wireless base station 100 is a group. Every one is different.

  In order to realize such grouping, the network device 10 in the upper layer of the radio base station 100 satisfies a condition that two adjacent radio base stations 100 belong to different groups by a genetic algorithm and a four-color theorem. Perform grouping processing to divide into groups.

  Thereby, in order to shorten the maintenance work time, when stopping the transmission power of a plurality of radio base stations 100 simultaneously, or when reducing the transmission power of the radio base station from the viewpoint of energy saving, As a result of the two adjacent radio base stations 100 stopping transmission power simultaneously, a wide dead zone does not occur, and the transmission power of the radio base station 100 is reduced while suppressing deterioration in the quality of communication services. Is possible.

  In the radio communication system 1 according to the present embodiment, when a radio base station is added to the radio communication system 1 or when a radio base station is excluded from the radio communication system 1, each radio base station 100 is The group ID of the group to which the own radio base station belongs is exchanged with another adjacent radio base station 100 by inter-base station communication. Thereby, each radio base station 100 can specify the group to which the other adjacent radio base station 100 belongs, and the own radio base station according to the change of the group to which the other adjacent radio base station 100 belongs. The regrouping process of changing the group to which can be performed can be performed. Furthermore, the radio base station 100 transmits the group ID of the group to which the own radio base station newly belongs to another adjacent radio base station 100. Thereby, it is possible to notify another adjacent radio base station 100 of the group to which the own radio base station newly belongs, and to perform the regrouping process in the other adjacent radio base station 100 as well. .

In the radio communication system 1 according to the present embodiment, when pre-blocking is performed in the radio base station 100, the radio base station 100 decreases the transmission power, while another adjacent radio base station 100 increases the transmission power. Let When attention is paid to one radio base station 100, a group to which the radio base station 100 belongs is different from a group to which another radio base station 100 adjacent to the radio base station 100 belongs. Therefore, when pre-blocking is performed in units of groups, when the transmission power of the radio base station 100 belonging to one group is reduced due to pre-blocking, other adjacent radio base stations 100 belonging to other groups The transmission power can be increased according to the request, and the transmission power of the radio base station 100 can be reduced while suppressing the deterioration of the quality of the communication service.
(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 100 belong to different groups, each radio base station 100 in the radio communication system 1 is divided into four groups. It may be divided into the above groups. For example, when each radio base station 100 in the radio communication system 1 is divided into five groups, a radio base station is added to the radio communication system 1 or a radio base station is excluded from the radio communication system 1 In the regrouping process in the case of being performed, it is possible to limit the range of the radio base station 100 in which the group is changed.

  In the above-described embodiment, the wireless communication system 1 is configured based on LTE Release 9 or LTE-Advanced, but may be configured 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.

  DESCRIPTION OF SYMBOLS 1 ... Wireless communication system, 10 ... Network apparatus, 12 ... Control part, 13 ... Memory | storage part, 14 ... Wired communication part, 52 ... Base station information acquisition part, 54 ... Grouping process part, 100a-100g ... Wireless base station, DESCRIPTION OF SYMBOLS 102 ... Control part, 103 ... Memory | storage part, 104 ... Wired communication part, 106 ... Wireless communication part, 108 ... Antenna, 152 ... Grouping information acquisition part, 154 ... Re-grouping process part, 156 ... Pre-occlusion start notification transmission part 158 ... Pre-occlusion start notification receiving unit, 160 ... Transmission power control unit, 162 ... Transmission power change stop notification transmission unit, 164 ... Transmission power change stop notification reception unit

Claims (9)

A wireless communication system having a plurality of wireless base stations,
By a genetic algorithm, the plurality of radio base stations are divided into groups that satisfy a condition that two adjacent radio base stations belong to different groups,
A radio communication system in which a time zone in which transmission power decreases in the radio base station differs for each group. Having a network device above the radio base station,
The network device includes a grouping processing unit that performs grouping to divide the plurality of radio base stations into groups satisfying a condition that two adjacent radio base stations belong to different groups by the genetic algorithm. The wireless communication system according to claim 1, further comprising:   The radio base station uses communication between base stations again 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. A regrouping unit that performs a regrouping process to divide the plurality of radio base stations into groups that satisfy a condition that two adjacent radio base stations belong to different groups by the genetic algorithm The wireless communication system according to claim 1 or 2. A radio base station that constitutes a radio communication system with other radio base stations,
According to the genetic algorithm, together with other radio base stations, it is divided into groups that satisfy the condition that two adjacent radio base stations belong to different groups,
A radio base station 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.   The radio base station according to claim 4, further comprising a pre-occlusion start notification transmission unit that transmits a pre-occlusion start notification indicating that pre-occlusion is started to the other adjacent radio base station.   6. The radio base station according to claim 4, further comprising a pre-occlusion start notification receiving unit that receives a pre-occlusion start notification indicating that the pre-occlusion is started, which is transmitted by the adjacent radio base station.   The transmission power change stop notification transmission part which transmits the transmission power change stop notification which shows starting the pre-blocking which shows stopping the change of transmission power with respect to said other adjacent radio base station is provided. 7. The radio base station according to any one of 6.   A transmission power change stop notification receiving unit that receives a transmission power change stop notification indicating start of pre-occlusion indicating that transmission power change is to be stopped transmitted by the other adjacent radio base station. The radio base station according to any one of 4 to 7. A network device above a plurality of radio base stations constituting a radio communication system,
A grouping processing unit for performing grouping by dividing the plurality of radio base stations into groups satisfying a condition that two adjacent radio base stations belong to different groups by a genetic algorithm;
A network device in which a time zone in which transmission power decreases in the radio base station differs for each group.

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