JP5995758B2 - Mobile communication network, radio base station, control station, and load balancing control method - Google Patents

Description

  The present invention relates to a mobile communication network, a radio base station, and a control station that distributes the load among the base stations by determining the connection destination cell of the mobile station based on the result of the base station load monitored by each base station. And a load distribution control method.

  In LTE (Long Term Evolution) standardized by 3GPP (3rd Generation Partnership Project), a heterogeneous network including a macro cell and a large number of small cells (such as a pico cell or a femto cell) is assumed. In a conventional heterogeneous network, CRE (Cell Range Expansion) has been proposed as a method of distributing the load of a macro cell (high power base station) to small cells (low power base stations) (for example, see Non-Patent Document 1). ). Note that the small cell has a feature that the fluctuation of the resource usage rate between cells (that is, the fluctuation of the load) is severe according to the user distribution or communication frequency that changes with time.

  The CRE described in Non-Patent Document 1 controls the small cell coverage by controlling the wireless terminal to connect to the small cell even when the received power from the small cell measured by the wireless terminal of the macro cell is not the highest. Is an extension.

  Further, when the load related to wireless communication (base station load) exceeds a threshold, the communication area is reduced (that is, the number of wireless terminals accommodated is reduced) by reducing the transmission power of the wireless base station. Furthermore, at the same time, a communication control method that maintains the quality of communication service by requesting another radio base station to increase transmission power has been proposed (see, for example, Patent Document 1).

International Publication No. 2011-078329 Pamphlet

“Efficient operation of small low-power base stations in LTE / LTE-Advanced heterogeneous head work”, IEICE technical report, October 2010, Vol. 110, no. 251, RCS2010-126, pp. 125-130

However, the prior art has the following problems.
In the prior art described in Patent Document 1, when the base station load exceeds the threshold value and is determined to be a high load, in order to compensate for the reduction of the communication area accompanying the decrease in transmission power, for all of the neighboring base stations, A request to increase transmission power is sent. However, the base station requested to increase the transmission power can reject this request according to the load of the own station. Therefore, when any of the neighboring base stations makes a rejection response to this request, load distribution among the base stations cannot be efficiently performed due to a decrease in transmission power.

  Further, in the conventional technique described in Patent Document 1, it is disclosed that a base station whose base station load exceeds a threshold value decreases transmission power after excluding the direction of the base station that has made a rejection response. However, when the antenna of the base station has an omni antenna configuration (antenna configuration often used in small cells), power control with such a narrowed direction cannot be performed, so this method cannot actually be used.

  The present invention has been made in order to solve the above-described problems. A mobile communication network and a radio base that can efficiently distribute the load between the base stations regardless of the antenna configuration of the base stations. An object is to obtain a station, a control station, and a load balancing control method.

  The mobile communication network according to the present invention communicates with a plurality of radio base stations that communicate with the mobile station when connected to the mobile station and one or more mobile stations existing within the coverage area to be provided. A mobile communication network comprising: a control station that performs overall control of load distribution of a plurality of radio base stations, wherein the mobile station transmits radio signals for all radio base stations that exist within an area in which the mobile station can communicate. The level measurement result is generated as a measurement result report message and notified to the actually connected radio base station, and each of the plurality of radio base stations is notified from each of the mobile stations that are actually connected. Base station load overlap usage rate for each of the other radio base stations corresponding to adjacent radio base stations having overlapping coverage areas for the mobile station based on the measurement result report message The base station load total usage rate is calculated and notified to the control station as base station statistical information. The control station determines the largest base station load total based on the base station statistical information notified from each of the plurality of radio base stations. If the radio base station that has notified the usage rate is specified as the first radio base station, and the total base station load usage rate in the first radio base station is greater than a preset first threshold, the first radio base station Based on the base station statistical information notified from the base station, an adjacent radio base station having the highest base station load overlap usage rate for the first radio base station is further identified as the second radio base station, and the second radio base station When the total base station load usage rate is smaller than a preset second threshold, a radio parameter notification for performing handover of the mobile station to the first radio base station with the second radio base station Me The first radio base station identifies the mobile station to be handed over to the second radio base station based on the radio parameter notification message notified from the control station, and performs load distribution It is.

  Further, the radio base station in the present invention is a radio base station applied to a mobile communication network, and performs a radio resource allocation process to a mobile station to communicate with, and monitors the allocation status, Is a measurement result that identifies another radio base station corresponding to an adjacent radio base station having an overlapping cover area for the mobile station based on a measurement result report message notified from each of the mobile stations that are actually connected For each other radio base station identified by the acquisition unit and the measurement result acquisition unit, a load information management unit that calculates the base station load overlap usage rate and the base station load total usage rate from the monitoring result by the radio resource control unit, Information including the other radio base stations identified by the measurement result acquisition unit, the base station load overlap usage rate calculated by the load information management unit, and the base station load total usage rate A statistical information generation unit that generates and notifies the control station as information, and the radio resource control unit, as the first radio base station, receives a radio parameter notification message from the control station, Based on this, a mobile station to be handed over with the second radio base station is specified, and load distribution is performed.

  Further, the control station in the present invention is a control station applied to a mobile communication network, and a statistical information acquisition unit that acquires base station statistical information notified from each of a plurality of radio base stations, and a statistical information acquisition unit Based on the base station statistical information notified from each of the plurality of wireless base stations acquired by the wireless base station, the wireless base station that has notified the largest total base station load usage rate is identified as the first wireless base station, and the first wireless base station is identified. When the total base station load usage rate in the base station is larger than a preset first threshold, the base station for the first radio base station based on the base station statistical information notified from the first radio base station An adjacent radio base station having the highest load overlap usage rate is further specified as the second radio base station, and the total base station load usage rate in the second radio base station is smaller than a preset second threshold value. In this case, a load distribution control unit that instructs the first radio base station to generate a radio parameter notification message for handover of the mobile station with the second radio base station, and a load distribution control unit And a radio parameter generation unit that generates a radio parameter notification message based on the command and notifies the first radio base station of the radio parameter notification message.

  In addition, the load distribution control method according to the present invention includes a mobile station, a plurality of radio base stations that communicate with the mobile station when connected to one or more mobile stations that exist in the provided coverage area, and a plurality of radio base stations. A load distribution control method that is executed in a mobile communication network including a control station that performs overall control of load distribution of a plurality of radio base stations. Including a step of generating a measurement result report message as a measurement result report message for all the radio base stations existing in the radio base station, and notifying the radio base stations currently connected, In the adjacent radio base station having the overlapping coverage area for the mobile station based on the measurement result report message notified from each of the mobile stations to which it is actually connected A base station load overlap usage rate and a base station load total usage rate are calculated for each of the other radio base stations corresponding to the above, and the control station is notified as base station statistical information. Based on the base station statistical information notified from each of the radio base stations, the radio base station that has notified the highest total base station load usage rate is identified as the first radio base station, and the base station in the first radio base station If the total load usage rate is larger than the preset first threshold, the base station load duplication usage rate for the first radio base station is based on the base station statistical information notified from the first radio base station. When the largest adjacent radio base station is further specified as the second radio base station, and the total base station load usage rate in the second radio base station is smaller than a preset second threshold, the first radio base station A radio parameter notification message for performing handover of the mobile station to the second radio base station, and the first radio base station includes a radio parameter notification message notified from the control station. Based on this, the mobile station to be handed over with the second radio base station is specified, and the step of performing load distribution is included.

  According to the present invention, the high load radio base station determined based on the result of the base station statistical information of each radio base station is the coverage area of the own station from the local radio base station to the low load adjacent radio base station. And the connection destination of the mobile station existing in the range where the cover area of the adjacent radio base station overlaps. Thereby, it is possible to obtain a mobile communication network, a radio base station, a control station, and a load distribution control method capable of efficiently distributing the base station load of each radio base station regardless of the antenna configuration of the base station.

It is a block diagram of the mobile communication network in Embodiment 1 of this invention. It is a block diagram of the radio base station in Embodiment 1 of this invention. It is a block diagram of the control station in Embodiment 1 of this invention. It is a block diagram of the mobile station in Embodiment 1 of this invention. It is explanatory drawing which showed an example of the load information which the wireless base station in Embodiment 1 of this invention manages. It is explanatory drawing which showed an example of the statistical information which the control station in Embodiment 1 of this invention manages. It is the flowchart which showed the procedure of the load distribution control which the control station in Embodiment 1 of this invention performs. It is explanatory drawing which showed an example of the sequence of the load distribution control in Embodiment 1 of this invention. It is explanatory drawing which showed an example of the statistical information which the control station in Embodiment 2 of this invention manages. It is a block diagram of the mobile communication network in Embodiment 3 of this invention. It is a block diagram of the radio base station in Embodiment 3 of this invention. It is explanatory drawing which showed an example of the sequence of the load distribution control in Embodiment 3 of this invention. It is a block diagram of the radio base station in Embodiment 4 of this invention. It is the flowchart which showed the procedure of the load distribution control which the wireless base station in Embodiment 4 of this invention performs.

  Hereinafter, a mobile communication network, a radio base station, a control station, and a load distribution control method according to the present invention will be described with reference to the drawings according to preferred embodiments. In the description of the drawings, the same reference numerals are assigned to the same elements, and duplicate descriptions are omitted.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram of a mobile communication network 1 according to Embodiment 1 of the present invention. As shown in FIG. 1, the mobile communication network 1 includes radio base stations 11 to 13, a control station 21, and mobile stations 31 to 35. Note that the number of radio base stations, control stations, and mobile stations in the mobile communication network 1 is not limited. Here, for specific explanation, the number of radio base stations is 3, the number of control stations is 1, The case where the number of stations is 5 is illustrated.

  In FIG. 1, each of the radio base stations 11 to 13 is a radio base station that provides a cover area (radio area). The cover area of the radio base station 11 is the same as the cover area of each of the radio base stations 12 and 13. There is an overlapping range. The dotted circles in FIG. 1 indicate the cover areas of the radio base stations 11 to 13, respectively.

  The control station 21 manages and manages the base station load in each of the three radio base stations 11 to 13 existing in the mobile communication network 1. Specifically, the control station 21 communicates with each of the radio base stations 11 to 13 and acquires base station statistical information to be described later from each of the radio base stations 11 to 13. Furthermore, the control station 21 sets radio parameters based on the acquired base station statistical information in order to distribute the base station loads of the radio base stations 11 to 13.

  Here, the base station load is an index indicating the load state of the base station, and for example, the amount of radio resources allocated to each mobile station, the CPU usage rate or the traffic amount can be used as an index. . As the number of mobile stations connected to the own station increases, these indices increase and the load on the base station increases. On the other hand, the smaller the number of mobile stations connected to the own station, the smaller these indexes become, and the lower the base station load.

  The mobile stations 31 to 35 move within the cover area while connecting to and communicating with any one of the radio base stations 11 to 13. For example, the mobile stations 31 to 35 include mobile communication devices such as mobile phones. Station. In FIG. 1, as a specific example of the initial connection destination, the mobile stations 31 to 34 are connected to the radio base station 11 and the mobile station 35 is connected to the radio base station 13. Yes.

  Next, a specific internal configuration will be described with reference to FIGS. 2 to 4 by taking each of the radio base station 11, the control station 21, and the mobile station 31 as an example. FIG. 2 is a configuration diagram of the radio base station 11 according to Embodiment 1 of the present invention. FIG. 3 is a configuration diagram of the control station 21 according to Embodiment 1 of the present invention. FIG. 4 is a configuration diagram of the mobile station 31 according to Embodiment 1 of the present invention.

  The radio base stations 12 and 13 have the same configuration as that of the radio base station 11, and the mobile stations 32 to 35 have the same configuration as that of the mobile station 31, and thus description thereof is omitted. In addition, the mobile stations 31 to 35 are assumed to be devices that have conventionally existed in mobile communication networks such as LTE. Further, it is assumed that the radio base stations 11 to 13 and the control station 21 perform only the extension necessary for the present invention. Therefore, the configuration of each device shows only the parts necessary for the description of the first embodiment.

  In FIG. 2, the radio base station 11 includes a radio communication unit 11a, an NW communication unit 11b, a measurement result acquisition unit 11c, a radio resource control unit 11d, a load information management unit 11e, a statistical information generation unit 11f, a radio parameter acquisition unit 11g, and A load information recording unit 11h is included.

  The radio communication unit 11 a communicates with each of the mobile stations 31 to 34 that are mobile stations connected within the cover area of the radio base station 11. On the other hand, the NW communication unit 11 b communicates with the control station 21. The measurement result acquisition unit 11c acquires the radio signal level measured by each of the mobile stations 31 to 34 in communication. The radio resource control unit 11d performs connection processing between the radio base station 11 and each of the mobile stations 31 to 34, and radio resource allocation processing for each of the mobile stations 31 to 34.

  Further, the load information management unit 11 e manages base station load information of the radio base station 11. The statistical information generation unit 11f generates base station statistical information for notification to the control station 21 based on the base station load information managed by the load information management unit 11e. The wireless parameter acquisition unit 11g acquires wireless parameter update information for distributing the base station load from the control station 21 via the NW communication unit 11b. Furthermore, the load information recording unit 11h records the base station load information of the radio base station 11 managed by the load information management unit 11e.

  In FIG. 3, the control station 21 includes an NW communication unit 21a, a statistical information acquisition unit 21b, a load distribution control unit 21c, a radio parameter generation unit 21d, and a statistical information recording unit 21e.

  The NW communication unit 21a communicates with each radio base station. The statistical information acquisition unit 21b acquires the base station statistical information notified by each radio base station via the NW communication unit 21a. The load distribution control unit 21c performs control processing for distributing the load of each radio base station based on each base station statistical information. The radio parameter generation unit 21d generates a radio parameter based on the control processing of the load distribution control unit 21c, and notifies the update information of the generated radio parameter to each radio base station via the NW communication unit 21a. Further, the statistical information recording unit 21e records the base station statistical information of each radio base station acquired by the statistical information acquisition unit 21b.

  In FIG. 4, the mobile station 31 includes a wireless communication unit 31a, a peripheral level measurement unit 31b, and a communication control unit 31c.

  The wireless communication unit 31a communicates with a connection destination wireless base station (corresponding to the wireless base station 11 in the example of FIG. 1). The peripheral level measurement unit 31b is configured to connect the wireless signal level of the connection-destination wireless base station 11 and the wireless signals of other wireless base stations (corresponding to the wireless base stations 12 and 13 in the example of FIG. 1) in the vicinity. Measure the level. Furthermore, the communication control unit 31c controls communication with the radio base station 11 via the radio communication unit 31a.

  Next, a series of operations in the radio base station 11, the control station 21, and the mobile station 31 in the mobile communication network 1 will be described with reference to FIGS. The radio base stations 12 and 13 perform the same operation as that of the radio base station 11, and the mobile stations 32 to 35 perform the same operation as that of the mobile station 31, and thus the description thereof is omitted.

  Further, hereinafter, as an example of the case where information on the amount of radio resources allocated to the connection destination mobile stations 31 to 34 is used as the base station load information managed by the load information management unit 11e in the radio base station 11. This will be described in detail.

  The radio resource control unit 11d in the radio base station 11 performs radio resource allocation processing according to radio quality and communication volume between the mobile station 31 to 34 and the mobile station 31 to 34 via the radio communication unit 11a. Do.

  Also, the radio resource control unit 11d monitors the allocation status within a predetermined time and aggregates the radio resource control unit 11d to obtain the radio resource usage allocated to each of the mobile stations 31 to 34. Furthermore, the radio resource control unit 11d calculates the total radio resource usage amount allocated to each of the mobile stations 31 to 34, thereby obtaining the total radio resource usage amount used as the own station. That is, the radio resource control unit 11d obtains the base station load applied to the own station by the connection of the mobile stations 31 to 34.

  Further, the radio resource control unit 11d calculates the ratio of the radio resource usage amount of each of the mobile stations 31 to 34 to the radio resource amount that can be used by the local station, so that the radio resource of each of the mobile stations 31 to 34 is calculated. Usage rates l (11, 31) to l (11, 34) can be obtained. Furthermore, the radio resource total usage rate L (11) is obtained by calculating the ratio of the radio resource total usage amount to the radio resource amount that can be used by the local station. That is, the radio resource control unit 11d obtains the ratio of the base station load currently applied to the own station to the maximum base station load that can be applied to the own station (hereinafter referred to as the total base station load usage rate). Will be.

  The radio resource usage rate l (11, 31) means the radio resource usage rate of the mobile station 31 communicating with the radio base station 11, and the radio resource total usage rate L (11) is the total radio base station 11 total. It means the usage rate.

  The radio resource control unit 11d includes base stations including the radio resource usage rates l (11, 31) to l (11, 34) of the mobile stations 31 to 34 and the radio resource total usage rate L (11). Load information is generated and notified to the load information management unit 11e.

  The load information management unit 11e records the base station load information notified from the radio resource control unit 11d in the load information recording unit 11h.

  On the other hand, the peripheral level measurement unit 31b in the mobile station 31 determines the radio signal level of the radio base station 11 that is the connection destination and the radio signal levels of the other radio base stations 12 and 13 existing around the own station. Measurement is performed via the wireless communication unit 31a. Here, the radio signal level of the radio base station means a reception level (sensitivity) between the radio base station and the mobile station.

  The peripheral level measurement unit 31b notifies the radio base station 11 that is the connection destination of the measurement result of the radio signal level of the radio base station 11 and the measurement results of the other radio base stations 12 and 13. Specifically, the peripheral level measurement unit 31b notifies the wireless base station 11 that is the connection destination of these measurement results as a measurement result report message via the wireless communication unit 31a. In this measurement result report message, the radio base station identifier and the radio signal level measurement result are stored in association with each other so that it can be understood from which radio base station the radio signal level measurement result is obtained. ing.

  In FIG. 1, for example, since the mobile station 31 does not exist in the cover area of the radio base station 13, the radio signal level of the radio base station 13 cannot be detected. In this case, the measurement result of the radio signal level of the radio base station 13 is not notified from the mobile station 31 to the radio base station 11.

  The measurement result acquisition unit 11c in the radio base station 11 receives the measurement result report message from the mobile station 31 via the radio communication unit 11a. In addition, the measurement result acquisition unit 11c is configured so that the mobile station 31 can detect the coverage area of the own station and the other based on the measurement result of the radio signal level of the own station and other radio base stations 12 and 13 included in the measurement result report message. It is determined whether or not the wireless base stations 12 and 13 exist in a range that overlaps the coverage areas (hereinafter referred to as overlapping areas). That is, the measurement result acquisition unit 11 c specifies a radio base station corresponding to an adjacent radio base station having a cover area overlapping with the mobile station 31.

  When the mobile station 31 exists in such an overlap area, the measurement result acquisition unit 11c selects a radio base station (in this case, the radio base station 12) corresponding to the overlap area, which is different from the radio base station 11, from the mobile station 31. Is notified to the load information management unit 11e. Thus, based on the measurement result report message from the mobile station 31 connected to the radio base station 11, it is determined that the radio base station 12 is an adjacent radio base station.

  The load information management unit 11e also records information that the adjacent radio base station of the mobile station 31 is the radio base station 12 in the load information recording unit 11h. More specifically, the load information management unit 11e associates information that associates the radio base station 12 that is an adjacent radio base station of the mobile station 31 with the radio resource usage rate l (11, 31) of the mobile station 31. It records in the load information recording part 11h.

  In addition, when a plurality of mobile stations have a common adjacent radio base station, the load information management unit 11e calculates the sum of the radio resource usage rates of these mobile stations to thereby determine the radio used in the overlapping area. A resource usage rate (hereinafter referred to as a radio resource duplication usage rate) is obtained. That is, the load information management unit 11e has a ratio of the base station load applied to its own station by connection of each mobile station existing in the overlap area to the maximum base station load that can be applied to the own station (hereinafter referred to as base station load This is referred to as the “duplicate usage rate”.

  Specifically, in FIG. 1, since each of the mobile station 31 and the mobile station 32 has the radio base station 12 as a common adjacent radio base station, the load information management unit 11e By calculating the sum of resource usage rates (= l (11, 31) + l (11, 32)), the radio resource overlapping usage rate L (11, 12) is obtained. The radio resource overlapping usage rate L (11, 12) means the radio resource overlapping usage rate when the adjacent radio base station of the mobile station communicating with the radio base station 11 is 12. Further, the load information management unit 11e records the radio resource overlapping usage rate L (11, 12) as base station load information in the load information recording unit 11h.

  Next, base station load information recorded in the load information recording unit 11h in the radio base station 11 will be described with reference to FIG. FIG. 5 is an explanatory diagram showing an example of base station load information managed by the radio base station 11 according to Embodiment 1 of the present invention.

  As shown in FIG. 5, the load information recording unit 11h associates, for each adjacent radio base station, the mobile station included in the overlap area, the radio resource usage rate of this mobile station, and the radio resource duplication usage rate. And recorded as base station load information.

  Specifically, as shown in FIG. 5, in the radio base station 12 that is an adjacent radio base station, the mobile station 31 and 32 included in the overlapping area and the radio resource usage rate l ( 11, 31), l (11, 32) and the radio resource overlapping usage rate L (11, 12) (= l (11, 31) + l (11, 32)) are recorded in association with each other. Further, the total radio resource utilization rate L (11) of the radio base station 11 is also recorded.

  In FIG. 1, the adjacent radio base station of the mobile station 34 is the radio base station 13. Therefore, as shown in FIG. 5, in the radio base station 13 which is an adjacent radio base station, the mobile station 34 included in the overlap area, the radio resource usage rate l (11, 34) of the mobile station 34, and the radio resource overlap The usage rate L (11, 13) (= l (11, 34)) is recorded in association with it. Note that the mobile station 34 is the only mobile station corresponding to the radio base station 13 that is an adjacent radio base station. In such a case, the radio resource usage rate l (11, 34) of the mobile station 34 is a radio resource duplication. It is recorded as the usage rate L (11, 13).

  In FIG. 1, since there is no adjacent radio base station of the mobile station 33, the mobile station 33 is not shown in FIG. 5. Further, in FIG. 1, since the radio base station 11 and the mobile station 35 are not connected, the mobile station 35 is not shown in FIG. Thus, mobile stations that exist only in the coverage area of the radio base station 11 and mobile stations that are not connected to the radio base station 11 are not included in the base station load information shown in FIG.

  Next, the statistical information generation unit 11f in the radio base station 11 includes the radio resource total usage rate L (11) in the base station load information (see FIG. 5) recorded in the load information recording unit 11h, Adjacent radio base stations (radio base stations 12, 13) and radio resource overlapping usage rates L (11, 12) and L (11, 13) are used as base station statistical information. Then, the statistical information generation unit 11f notifies the control station 21 of this base station statistical information via the NW communication unit 11b as a statistical report message. The notification of the statistical report message to the control station 21 may be performed periodically or only when there is a change.

  Here, in FIG. 1, since the radio base station 12 has no mobile station connected to itself, the radio base station 12 controls only the total radio resource utilization rate L (12) as base station statistical information. The station 21 is notified.

  In FIG. 1, the radio base station 13 is connected to the mobile station 35, and the mobile station 35 exists in a range where the cover area of the own station and the cover area of the radio base station 11 overlap. Therefore, the radio base station 13 uses the radio resource total usage rate L (13), the adjacent radio base station (radio base station 11), and the radio resource overlapping usage rate L (13, 11) as base station statistical information. The control station 21 is notified.

  The statistical information acquisition unit 21b in the control station 21 records the base station statistical information included in the statistical report message received from the radio base station 11 via the NW communication unit 21a in the statistical information recording unit 21e. Similarly, the statistical information acquisition unit 21b also receives the base station statistical information from the other radio base stations 12 and 13 as a statistical report message via the NW communication unit 21a and records it in the statistical information recording unit 21e. To do.

  Next, the base station statistical information recorded in the statistical information recording unit 21e in the control station 21 will be described with reference to FIG. FIG. 6 is an explanatory diagram showing an example of base station statistical information managed by the control station 21 according to Embodiment 1 of the present invention.

  As shown in FIG. 6, the statistical information recording unit 21e includes, for each radio base station (acquired radio base station) that acquired the base station statistical information, the total radio resource usage rate of the acquired radio base station and the adjacent radio base station. And the radio resource duplication usage rate are associated with each other and recorded as base station statistical information.

  Specifically, as illustrated in FIG. 6, in the radio base station 11 that is the acquired radio base station, the radio resource total usage rate L (11) of the radio base station 11 and the radio base station 12 that is the adjacent radio base station. , 13 and the radio resource overlapping usage rates L (11, 12) and L (11, 13) are recorded in association with each other.

  Further, as shown in FIG. 6, the radio resource total usage rate L (12) is recorded in the radio base station 12 that is the acquired radio base station. In addition, as shown in FIG. 6, in the radio base station 13 that is the acquired radio base station, the radio resource total usage rate L (13), the radio base station 11 that is the adjacent radio base station, and the radio resource overlapping usage rate L (13, 11) are recorded in association with each other.

  In addition, a threshold of the total radio resource usage corresponding to each acquired radio base station is also set in advance and recorded together with the statistical information recording unit 21e. The load distribution control unit 21c determines that the base station load is high if the total radio resource usage rate of each acquired radio base station is greater than a preset threshold, and if the radio resource total usage rate is less than the preset threshold, Judged as low load.

  The threshold is, for example, a value that is lower than the upper limit of the total radio resource usage rate allowed in each acquired radio base station, and specifically, so that congestion does not occur or communication restrictions do not occur. Stipulate. Further, the threshold value can be changed depending on the time zone.

  Next, load distribution control performed by the load distribution control unit 21c based on the base station statistical information recorded in the statistical information recording unit 21e in the control station 21 will be described with reference to FIG. FIG. 7 is a flowchart showing a procedure of load distribution control by the control station 21 in the first embodiment of the present invention.

  In the case where the flowchart of FIG. 7 is specifically described with reference to FIG. 6, L (11), L (12), and L (13) become smaller in this order, and L (11, 12) is larger than L (11, 13) and L (13, 11). Further, L (11) exceeds a threshold value (first threshold value) corresponding to the radio base station 11, L (12) is less than a threshold value (second threshold value) corresponding to the radio base station 12, and L13 Is less than the threshold value corresponding to the radio base station 13 (third threshold value). That is, the following description will be made assuming that the radio base station 11 is a high-load radio base station and the radio base stations 12 and 13 are low-load radio base stations.

  Here, the load distribution control unit 21c in the control station 21 starts the load distribution control according to the flowchart of FIG. 7 when, for example, a preset time or a preset amount of information is reached. This amount of information is defined based on the amount of data notified from each radio base station to the control station 21 as a statistical report message.

  First, in step S101, the load distribution control unit 21c selects the acquired radio base station having the highest radio resource total usage rate from the base station statistical information recorded in the statistical information recording unit 21e. Specifically, as shown in FIG. 6, the radio base station 11 corresponding to the total radio resource usage rate L (11) is selected.

  Next, in step S102, the load distribution control unit 21c determines whether or not the total radio resource usage rate of the selected acquired radio base station is larger than a preset threshold value.

  In step S102, when the load distribution control unit 21c determines that the total radio resource usage rate of the selected acquired radio base station is equal to or less than a preset threshold, the process proceeds to step S106 described below.

  On the other hand, if the load distribution control unit 21c determines in step S102 that the total radio resource usage rate of the selected acquired radio base station is greater than a preset threshold value, the process proceeds to step S103. Specifically, as shown in FIG. 6, since the total radio resource utilization rate L (11) of the radio base station 11 is larger than the first threshold value, the process of step S103 is executed.

  Next, in step S103, the load distribution control unit 21c selects an adjacent radio base station with the highest radio resource duplication usage rate corresponding to the selected acquired radio base station. Specifically, as shown in FIG. 6, since the radio resource duplication usage rate L (11, 12) is the largest, the radio base station 12 is selected as the adjacent radio base station corresponding to this. Become.

  Next, in step S104, the load distribution control unit 21c determines whether or not the total radio resource usage rate of the selected adjacent radio base station is less than a preset threshold value.

  In step S104, when the load distribution control unit 21c determines that the total radio resource usage rate of the selected adjacent radio base station is equal to or greater than a preset threshold, the process returns to step S103. In this case, in step S103, the load distribution control unit 21c selects an adjacent radio base station with the next highest radio resource duplication usage rate, and executes the process of step S104 again.

  On the other hand, if the load distribution control unit 21c determines in step S104 that the total radio resource usage rate of the selected adjacent radio base station is less than a preset threshold value, the process proceeds to step S105. Specifically, as shown in FIG. 6, since the total radio resource utilization rate L (12) of the radio base station 12 is smaller than the second threshold value, the process of step S105 is executed.

  Next, in step S105, the load distribution control unit 21c determines that load distribution from the selected acquired radio base station to the selected adjacent radio base station is possible. Specifically, it is determined that load distribution from the radio base station 11 to the radio base station 12 is possible.

  Next, in step S106, the load distribution control unit 21c determines whether or not the process of step S102 has been executed for all of the acquired radio base stations included in the base station statistical information recorded in the statistical information recording unit 21e. To do.

  In step S106, when the load distribution control unit 21c determines that the process of step S102 has not been executed for all of the acquired radio base stations included in the base station statistical information, the process returns to step S101. In this case, in step S101, the load distribution control unit 21c selects an acquired radio base station having the next highest radio resource total usage rate after the selected acquired radio base station. Specifically, the radio base station 12 corresponding to the radio resource total usage rate L (12) that is the next higher than the radio resource total usage rate L (11) of the radio base station 11 is selected.

  On the other hand, when the load distribution control unit 21c determines in step S106 that the process of step S102 has been executed for all of the acquired radio base stations included in the base station statistical information, the process proceeds to step S107. Specifically, if the load distribution control unit 21c executes the process of step S102 for the radio base stations 12 and 13, the load distribution control unit 21c executes the process of step S102 for all of the acquired radio base stations included in the base station statistical information. Therefore, the process proceeds to step S107.

  As described above, the load distribution control unit 21c performs the above-described process for all acquired radio base stations included in the base station statistical information recorded in the statistical information recording unit 21e, and finally proceeds to Step S107. Proceed with

  Next, in step S107, the load distribution control unit 21c generates, in the radio parameter generation unit 21d, a radio parameter notification message for the acquired radio base station that has been determined in step S105 that load distribution to adjacent radio base stations is possible. The control command is performed as follows. Specifically, as shown in FIG. 6, a radio parameter notification message is generated for the radio base station 11 that is determined to be able to distribute the load to the radio base stations 12 that are adjacent radio base stations. . Thereafter, the load distribution control unit 21c ends the series of processes in the flowchart of FIG.

  Here, the radio parameter notification message includes, as radio parameters, an identifier of an acquired radio base station that is determined to be load-distributable to adjacent radio base stations, an identifier of an adjacent radio base station that is load-balanced, and these And a radio resource duplication usage rate corresponding to the base station. Specifically, the identifier of the radio base station 11, the identifier of the radio base station 12, and the radio resource overlapping usage rate L (11, 12) are included.

  Next, a series of operations for switching the connection destination of the mobile station from the high load radio base station to the low load adjacent radio base station performed after the radio parameter notification message is generated will be described with reference to FIG. . FIG. 8 is an explanatory diagram showing an example of a load balancing control sequence according to Embodiment 1 of the present invention. FIG. 8 also shows the above-described measurement result report message and statistical report message.

  As shown in FIG. 8, the radio parameter notification message generated by the radio parameter generation unit 21d is a radio that is an acquired radio base station that is determined to be able to distribute the load to adjacent radio base stations via the NW communication unit 21a. The base station 11 is notified.

  Also, the radio parameter acquisition unit 11g in the radio base station 11 sets the radio parameter included in the received radio parameter notification message in the radio resource control unit 11d. The radio resource control unit 11d performs the following processing based on this radio parameter.

  That is, the radio resource control unit 11d in the radio base station 11 determines the allowable radio resource total usage rate of the adjacent radio base station notified by the radio parameter notification message among the mobile stations communicating with the own station in the overlapping area. The mobile station for switching the connection destination is selected so as not to exceed.

  In other words, the radio resource control unit 11d does not select all mobile stations that communicate with the local station in such overlapping areas as mobile stations for switching connection destinations, but moves some of these mobile stations. The station is selected as a mobile station for switching the connection destination. Then, the radio resource control unit 11d switches the connection destination of the selected mobile station from its own station to the adjacent radio base station. Note that such a switching operation of the radio resource control unit 11d is performed for a mobile station that has newly reported a measurement result of the overlapping area in the future, instead of being performed for the mobile station communicating with the own station in the overlapping area. May be performed. Further, hereinafter, in order to explain specifically, a case where the radio resource control unit 11d selects the mobile station 31 among the mobile stations 31 and 32 is illustrated.

  Specifically, the radio resource control unit 11d performs a procedure for switching the connection destination from the local station to the adjacent radio base station using the conventional handover procedure between the radio base stations for the selected mobile station. , Distribute the base station load of its own station.

  More specifically, as illustrated in FIG. 8, the radio resource control unit 11 d notifies the handover request message to the radio base station 12 which is an adjacent radio base station to be load-balanced, and this radio base station 12 When a handover response message is received, a radio base station switching instruction message is notified to the selected mobile station 31.

  When receiving the radio base station switching instruction message, the mobile station 31 switches the connection destination from the radio base station 11 to the radio base station 12 corresponding to the received message, and notifies the radio base station 12 of a radio base station switching completion message. To do. When receiving the radio base station switching completion message from the mobile station 31, the radio base station 12 notifies the handover source radio base station 11 of the handover completion message.

  By completing such a series of switching procedures, the radio base station 11 can distribute the base station load of its own station to the radio base station 12 which is an adjacent radio base station as a result.

  In summary, the mobile communication network 1 according to the first embodiment distributes the base station load of each radio base station in the following procedure.

  That is, each radio base station manages base station load information based on information on the amount of radio resources allocated to the mobile station communicating with the own station and the measurement result of the radio signal level measured by the mobile station. In addition, the base station statistical information is notified to the control station 21. Further, the control station 21 detects the load state of each radio base station from the base station statistical information generated based on the base station load information acquired from each radio base station.

  Further, the control station 21 selects an overlapping area in which the load distribution of the high-load radio base stations can be distributed from the range in which the cover area of the high-load radio base station and the cover area of the low-load radio base station overlap. decide. Then, the control station 21 commands the high load radio base station so that the mobile stations existing in the overlapping area are connected to the low load radio base station. Thereby, the base station load of each radio base station is distributed. In addition, each mobile station connected to the radio base station is expected to improve user throughput because a large amount of radio resources can be allocated.

  Also, unlike the conventional technology, the base station load of the own station is not distributed by power control in a narrow direction, so the base station load of the own station is efficiently distributed regardless of the antenna configuration of the base station. be able to.

  As described above, according to the first embodiment, the high-load radio base station determined based on the result of the base station statistical information of each radio base station is compared with the low-load adjacent radio base station from the own station. The connection destination of the mobile station existing in a range where the cover area of the own station and the cover area of the adjacent radio base station overlap is switched.

  Thereby, the base station load of each radio base station can be efficiently distributed regardless of the antenna configuration of the base station, and the base station load of a high load radio base station can be reduced. In addition, since it is not necessary for the control station to hold the wireless base station adjacency information in advance in the processing of the control station, in addition to simplifying the pre-configuration of the control station, it is possible to add or delete the wireless base station during operation. Even when it occurs, load distribution control can be executed continuously.

  In the first embodiment, the measurement result report message may be a Measurement Report message defined in 3GPP and used in LTE. Similarly, the handover request message may be a Handover Request message, and the handover response message may be a Handover Request Acknowledge message.

  Similarly, the radio base station switching instruction message may be an RRC Connection Reconfiguration message, the radio base station switching completion message may be an RRC Connection Reconfiguration Complete message, and the handover completion message may be a UE Context Release message. .

  In the first embodiment, as described above, the radio resource amount (total radio resource usage rate, radio resource overlapping usage rate, etc.) is specifically described as an index of the base station load. However, the present invention is not limited to this. Not. That is, the same effect can be obtained by using, for example, the CPU usage rate or the traffic amount instead of the radio resource amount as an index of the base station load.

Embodiment 2. FIG.
In the first embodiment, the case has been described where each radio base station notifies base station statistical information to the control station 21 regardless of the load state of the own station. On the other hand, in Embodiment 2 of the present invention, a case will be described in which each radio base station notifies base station statistical information to the control station 21 according to the load state of the own station.

  Here, the second embodiment has a technical feature that the information amount of the base station statistical information notified from each radio base station to the control station 21 can be reduced as compared with the first embodiment.

  In addition, since each radio base station, control station, and each mobile station constituting mobile communication network 1 in the second embodiment are the same as those in the first embodiment, hereinafter, the same as in the first embodiment. The difference will be mainly described.

  First, each radio base station and each mobile station in the second embodiment perform the same operation as in the first embodiment, and the load information recording unit 11h in the radio base station 11 has the same configuration as that shown in FIG. Assume that the indicated base station load information is recorded.

  In this case, the load information management unit 11e in the radio base station 11 determines that the base station load is high when the radio resource total usage rate L (11) is larger than a preset threshold value. If the threshold is less than or equal to the preset threshold, the base station load is determined to be low.

  In the second embodiment, as in the first embodiment, a threshold for the total radio resource utilization rate corresponding to each radio base station is set in advance and recorded together with the load information recording unit 11h.

  The statistical information generation unit 11f in the radio base station 11 performs the same operation as in the first embodiment when the load information management unit 11e determines that the base station load is high. That is, the statistical information generation unit 11f includes the radio resource total usage rate L (11), the adjacent radio base stations (radio base stations 12, 13), and the radio resource overlapping usage rates L (11, 12), L (11, 13) is notified to the control station 21 by a statistical report message.

  On the other hand, the statistical information generation unit 11f in the radio base station 11 performs an operation different from that of the first embodiment when the load information management unit 11e determines that the base station load is low. That is, the statistical information generating unit 11f uses the statistical report message to transmit the base station statistical information including only the radio resource total usage rate L (11) among the base station load information recorded in the load information recording unit 11h. 21 is notified.

  The statistical information acquisition unit 21b in the control station 21 records the base station statistical information included in the statistical report message received from each radio base station in the statistical information recording unit 21e.

  Specifically, as in the first embodiment, the radio resource total usage rate L (11) of the radio base station 11 is larger than the first threshold, and the radio resource total usage rates L ( 12) When assuming that L (13) is less than the second threshold and the third threshold, the statistical information is recorded in the statistical information recording unit 21e as shown in FIG. FIG. 9 is an explanatory diagram showing an example of statistical information managed by the control station 21 according to Embodiment 2 of the present invention.

  Here, the radio base station 11 determines that the base station load of the own station is high because the radio resource total usage rate L (11) of the own station is larger than the preset first threshold value. In this case, as shown in FIG. 9, in the radio base station 11 that is the acquired radio base station, the radio resource total usage rate L (11) of the radio base station 11 and the radio base station 12 that is the adjacent radio base station. , 13 and the radio resource overlapping usage rates L (11, 12) and L (11, 13) are recorded in association with each other.

  Also, the radio base station 13 determines that the base station load of the local station is low because the radio resource total usage rate L (13) of the local station is less than the preset third threshold. In this case, as shown in FIG. 9, only the total radio resource utilization rate L (13) is recorded, and unlike the first embodiment, the total radio resource utilization rate L (13, 11) and the adjacent radio The base station (wireless base station 11) is not recorded. This is because, as described above, only the radio resource total usage rate L (13) is notified to the control station 21.

  As described above, when the base station load of the radio base station 13 is less than the preset third threshold, the radio base station 13 notifies only the radio resource total usage rate L (13) of the own station. Thereby, the information amount (total amount) of the base station statistical information notified from the radio base station 13 to the control station 21 is reduced as compared with the first embodiment.

  Then, the control station 21 performs the same operation as that in the first embodiment based on the base station statistical information recorded in the statistical information recording unit 21e, and as a result, the connection destination of the mobile station Is switched from a high-load radio base station to a low-load adjacent radio base station.

  As described above, according to the second embodiment, the radio base station changes the content of the base station statistical information notified to the control station according to the load state of the own station. Specifically, when the radio base station determines that the load on the local station is low, the radio base station notifies only the total radio resource usage rate of the local station to the control station as base station statistical information, unlike when the load is determined to be high. To do.

  As a result, the amount of information notified from the low-load radio base station to the control station is limited, so that the information amount of the base station statistical information acquired from each radio base station by the control station can be reduced. In addition, it is possible to effectively suppress the amount of information that increases as the number of radio base stations in the mobile communication network increases.

Embodiment 3 FIG.
In the first and second embodiments, the case where the control station 21 acquires base station statistical information from each radio base station and generates radio parameters for distributing the load has been described. On the other hand, in Embodiment 3 of the present invention, the load distribution function (overall control function) of the control station 21 is provided in any one of the radio base stations, and the radio base station having the load distribution function is the control station 21. A case where a radio parameter is generated instead of will be described.

  Here, the third embodiment is a dedicated device for performing load distribution control by providing any one of the radio base stations with the load distribution function of the control station 21 in the first and second embodiments. The technical feature is that it is not necessary to provide the control station 21.

  FIG. 10 is a configuration diagram of the mobile communication network 1A according to Embodiment 3 of the present invention. As shown in FIG. 10, mobile communication network 1A includes radio base stations 11A to 13A and mobile stations 31 to 35, and does not include control station 21 in the first embodiment.

  Note that, as in the first embodiment, the number of radio base stations and mobile stations in the mobile communication network 1A is not limited. For the sake of specific explanation, the number of radio base stations is 3, The case where the number of mobile stations is 5 is illustrated. Further, the case where the radio base station 11A is selected from the radio base stations 11A to 13A as the radio base station having the load distribution function will be described as an example. However, the case where another radio base station is selected is described. Is the same.

  Next, the configuration of the radio base station 11A will be described with reference to FIG. FIG. 11 is a configuration diagram of the radio base station 11A according to Embodiment 3 of the present invention. The configurations of the radio base stations 12A and 13A may be the same as those in FIG. 2, and the configurations of the mobile stations 31 to 35 may be the same as those in FIG.

  In FIG. 11, the radio base station 11A has the same configuration as in the first embodiment, and further, as a load distribution function, a statistical information acquisition unit 11i, a load distribution control unit 11j, a radio parameter generation unit 11k, and a statistical It has an information recording part 11l.

  Next, a series of operations in the radio base station 11A, the radio base station 12A, and the mobile station 31 in the mobile communication network 1A will be described with a focus on differences from the first embodiment with reference to FIG. The radio base station 13A performs the same operation as that of the radio base station 12A, and the mobile stations 32 to 35 perform the same operation as that of the mobile station 31, and thus the description thereof is omitted. Each mobile station performs the same operation as in the first embodiment.

  First, each radio base station and each mobile station in the third embodiment perform the same operation as in the first embodiment, and the load information recording unit 11h in the radio base station 11A has the same configuration as that shown in FIG. Assume that the indicated base station load information is recorded.

  In this case, the statistical information generation unit 11f in the radio base station 11A includes the radio resource total usage rate L (11) in the base station load information (see FIG. 5) recorded in the load information recording unit 11h. Adjacent radio base stations (radio base stations 12, 13) and radio resource overlapping usage rates L (11, 12) and L (11, 13) are used as base station statistical information. Then, the statistical information generation unit 11f notifies the statistical information acquisition unit 11i of this base station statistical information. Further, the statistical information acquisition unit 11i records the received base station statistical information in the statistical information recording unit 11l.

  On the other hand, the statistical information generation unit in the radio base station 12A uses the radio resource total usage rate L (12) recorded in the load information recording unit in the own station as base station statistical information, and performs NW communication in the own station. The wireless base station 11A is notified by a statistical report message.

  Then, the statistical information acquisition unit 11i in the radio base station 11A records the base station statistical information included in the statistical report message received from the radio base station 12A via the NW communication unit 11b in the statistical information recording unit 11l. As a result, the base station statistical information shown in FIG. 6 is similarly recorded in the statistical information recording unit 11l. Note that the statistical information recording unit 11l may record the base station statistical information shown in FIG.

  Next, load distribution control performed by the load distribution control unit 11j based on the base station statistical information recorded in the statistical information recording unit 11l in the radio base station 11A will be described with reference to FIG. The load distribution control unit 11j executes the same processing as in the first embodiment in steps S101 to S106 in the flowchart of FIG.

  In step S107, the load distribution control unit 11j performs control so that the radio parameter generation unit 11k generates a radio parameter notification message for the acquired radio base station that is determined to be capable of load distribution to adjacent radio base stations in step S105. Make a command. Thereafter, the load distribution control unit 11j ends a series of processes in the flowchart of FIG.

  Here, when the acquired radio base station that is determined to be capable of load distribution to adjacent radio base stations is the own station (radio base station 11), the destination of the generated radio parameter message is the own station. Therefore, the generated wireless parameter is notified to the wireless parameter acquisition unit 11g via the NW communication unit 11b.

  On the other hand, if the acquired radio base station that is determined to be able to distribute the load to adjacent radio base stations is other than its own (radio base stations 12 and 13), the destination of the generated radio parameter message is its own. Other than the station. Therefore, the generated radio parameters are notified to a radio base station other than the own station via the NW communication unit 11b.

  Next, a series of operations for switching the connection destination of the mobile station from the high load radio base station to the low load adjacent radio base station, which is performed after the radio parameter notification message is generated, will be described with reference to FIG. . FIG. 12 is an explanatory diagram showing an example of a load balancing control sequence according to Embodiment 3 of the present invention.

  Comparing FIG. 12 with the previous FIG. 8, the statistical report message notified to the control station 21 is notified to the wireless base station 11A, and the wireless parameter notification message notified from the control station 21 is It can be seen that the station 11A notifies.

  That is, in the first and second embodiments, the operation performed by the control station 21 is performed instead by the radio base station 11A having the load distribution function. Thereby, even if the control station 21 is not provided in the mobile communication network 1A, the same effect as in the first and second embodiments can be obtained.

  As described above, according to the third embodiment, any one of the radio base stations has the load distribution function of the control station in the first and second embodiments. Thus, the same effect as in the first and second embodiments can be obtained without providing a control station, which is a dedicated device for performing load distribution control, in the mobile communication network.

Embodiment 4 FIG.
In the third embodiment, the case where the load distribution function of the control station 21 is provided in any of the radio base stations in the mobile communication network 1A has been described. On the other hand, in the fourth embodiment of the present invention, a case will be described in which the load distribution function of the control station 21 is divided and provided for all the radio base stations in the mobile communication network 1B.

  Here, in the fourth embodiment, by dividing the load distribution function of the control station 21 into each radio base station, it is not necessary to provide the control station 21 that is a dedicated device for performing load distribution control. As a radio base station having a load distribution function, it is not necessary to select any one of the radio base stations.

  The mobile communication network 1B according to the fourth embodiment is composed of radio base stations 11B to 13B and mobile stations 31 to 35, and does not include the control station 21 as in the third embodiment.

  Note that, as in the third embodiment, the number of radio base stations and mobile stations in the mobile communication network 1B is not limited, and here, in order to explain specifically, the number of radio base stations is 3, The case where the number of mobile stations is 5 is illustrated.

  Next, the configuration of the radio base station 11B will be described with reference to FIG. FIG. 13 is a configuration diagram of the radio base station 11B according to Embodiment 4 of the present invention. The configurations of the radio base stations 12B and 13B are the same as those of the radio base station 11B. The configuration of the mobile stations 31 to 35 may be the same as that in FIG.

  In FIG. 13, the radio base station 11B includes a radio communication unit 11a, an NW communication unit 11b, a measurement result acquisition unit 11c, a radio resource control unit 11d, a load information management unit 11e, a statistical information generation unit 11f, a load information recording unit 11h, It has a statistical information acquisition unit 11i, a load distribution control unit 11j, and a statistical information recording unit 11l. Here, when the radio base station 11B in the fourth embodiment and the radio base station 11A in the third embodiment are compared, the radio base station 11B includes a radio parameter acquisition unit 11g and a radio parameter generation unit 11k. Not included. The load distribution control unit 11j is directly connected to the radio resource control unit 11d and the NW communication unit 11b.

  Next, a series of operations in the radio base station 11B and the mobile station 31 in the mobile communication network 1B will be described with reference to FIG. Note that the radio base stations 12B and 13B perform the same operation as the radio base station 11B, and the mobile stations 32 to 35 perform the same operation as the mobile station 31, and thus the description thereof is omitted. Each mobile station performs the same operation as in the first embodiment.

  First, each radio base station and each mobile station in the fourth embodiment perform the same operation as in the first embodiment, and the load information recording unit 11h of the radio base station 11B is shown in FIG. Assume that base station load information is recorded.

  In this case, the statistical information generation unit 11f in the radio base station 11B uses the base station load information recorded in the load information recording unit 11h (see FIG. 5 above), and the total radio resource usage rate L (11). The adjacent radio base stations (radio base stations 12 and 13) and the radio resource overlapping usage rates L (11, 12) and L (11, 13) are used as base station statistical information. Then, the statistical information generation unit 11f notifies the statistical information acquisition unit 11i of this base station statistical information. Further, the statistical information acquisition unit 11i records the received base station statistical information in the statistical information recording unit 11l.

  Further, the statistical information generation unit 11f in the radio base station 11B notifies the base station statistical information to the radio base stations 12B and 13B other than the own station through the NW communication unit 11b by a statistical report message.

  The statistical information acquisition unit 11i in the radio base station 11B also records the base station statistical information received from the radio base stations 12B and 13B in the statistical information recording unit 11l.

  As a result, the base station statistical information shown in FIG. 6 is similarly recorded in each of the statistical information recording unit 11l in the wireless base station 11B and the statistical information recording unit in the wireless base stations 12B and 13B. The Rukoto. Note that the base station statistical information shown in FIG. 9 may be recorded in these statistical information recording units.

  Next, load distribution control performed by the load distribution control unit 11j based on the base station statistical information recorded in the statistical information recording unit 11l in the radio base station 11B will be described with reference to FIG. FIG. 14 is a flowchart showing a procedure of load distribution control by radio base station 11B in the fourth embodiment of the present invention. In the flowchart of FIG. 14, the description will focus on differences from the first embodiment.

  First, in step S201, the load distribution control unit 11j determines whether or not the radio resource total usage rate L (11) of the local station is larger than a preset first threshold value.

  In step S201, when the load distribution control unit 11j determines that the radio resource total usage rate L (11) of the local station is equal to or less than the first threshold set in advance, the series of processing ends.

  On the other hand, if the load distribution control unit 11j determines in step S201 that the radio resource total usage rate L (11) of the own station is larger than the preset first threshold value, the process proceeds to step S202.

  Next, in step S202, the load distribution control unit 11j selects an adjacent radio base station corresponding to the own station and having the highest radio resource duplication usage rate.

  Next, in step S203, the load distribution control unit 11j determines whether or not the total radio resource usage rate of the selected adjacent radio base station is less than a preset threshold value.

  In step S203, when the load distribution control unit 11j determines that the total radio resource usage rate of the selected adjacent radio base station is equal to or greater than a preset threshold, the process returns to step S202. In this case, in step S202, the load distribution control unit 11j selects an adjacent radio base station having the next highest radio resource duplication usage rate, and executes the process of step S203 again.

  On the other hand, when the load distribution control unit 11j determines in step S203 that the total radio resource usage rate of the selected adjacent radio base station is less than a preset threshold value, the process proceeds to step S204.

  Next, in step S204, the load distribution control unit 11j determines that load distribution to the adjacent radio base station selected from the own station is possible, and ends a series of processes in the flowchart of FIG.

  Further, when the load distribution control unit 11j determines that load distribution from the own station to the adjacent radio base station is possible, the identifier of the adjacent radio base station to be load-distributed and the radio corresponding to the adjacent radio base station The resource overlapping usage rate is notified to the radio resource control unit 11d.

  Then, similarly to the first embodiment, the radio resource control unit 11d switches the connection destination of the mobile station from its own station, which is a high-load radio base station, to an adjacent radio base station with a low load.

  In this way, each wireless base station has its own base station load high, and when it is determined that load distribution from the local station to the adjacent wireless base station is possible, the wireless base station has a low load adjacent wireless base station. Switch the connection destination of the mobile station to the station. On the other hand, in the above-described third embodiment, one radio base station having a load balancing function loads a load from a high load radio base station in each radio base station to a low load adjacent radio base station. Each radio base station switches the connection destination of the mobile station from its own station to an adjacent radio base station with a low load based on a radio parameter notification message to be notified when it is determined that dispersion is possible.

  Therefore, compared with the previous third embodiment, in the fourth embodiment, it is not necessary to select any one of the radio base stations in advance as a radio base station having a load distribution function. Even if a radio base station having a load distribution function is deleted, load distribution control can be continuously executed.

  As described above, according to the fourth embodiment, the load distribution function of the control station is not provided in any one of the radio base stations in the mobile communication network, but is provided separately for each radio base station. As a result, the same effect as in the third embodiment can be obtained without selecting any of the radio base stations in the mobile communication network in advance as a radio base station having a load distribution function.

  1, 1A, 1B mobile communication network, 11-13, 11A-13A, 11B-13B wireless base station, 11a wireless communication unit, 11b NW communication unit, 11c measurement result acquisition unit, 11d radio resource control unit, 11e load information management Unit, 11f statistical information generation unit, 11g wireless parameter acquisition unit, 11h load information recording unit, 11i statistical information acquisition unit, 11j load distribution control unit, 11k wireless parameter generation unit, 11l statistical information recording unit, 21 control station, 21a NW Communication part, 21b Statistical information acquisition part, 21c Load distribution control part, 21d Wireless parameter generation part, 21e Statistical information recording part, 31-35 Mobile station, 31a Wireless communication part, 31b Perimeter level measurement part, 31c Communication control part.

Claims (9)

A mobile station,
A plurality of radio base stations that communicate with the mobile station when connected to one or more mobile stations present in the coverage area to be provided;
A control station that communicates with the plurality of radio base stations and performs overall control of load distribution of the plurality of radio base stations;
A mobile communication network comprising:
The mobile station
For all the radio base stations that are within the area where they can communicate, generate the measurement result report message as a result of measuring the radio signal level, notify the currently connected radio base station,
Each of the plurality of radio base stations
For each other radio base station corresponding to an adjacent radio base station having an overlapping cover area for the mobile station based on the measurement result report message notified from each of the mobile stations that are actually connected , Base station load duplication usage rate, and base station load total usage rate is calculated and notified to the control station as base station statistical information,
The control station
Based on the base station statistical information notified from each of the plurality of wireless base stations, the wireless base station that has notified the largest total base station load usage rate is identified as the first wireless base station, and the first wireless base station When the base station load total usage rate in the base station is larger than a preset first threshold, the first radio base station is based on the base station statistical information notified from the first radio base station. The adjacent radio base station having the largest base station load overlap usage rate for the station is further specified as the second radio base station, and the total base station load usage rate in the second radio base station is set to a second threshold value set in advance. If smaller than, notify the first radio base station a radio parameter notification message for handover of the mobile station with the second radio base station,
The first radio base station is
A mobile communication network that identifies a mobile station to be handed over with the second radio base station based on the radio parameter notification message notified from the control station, and performs load distribution. A radio base station applied to the mobile communication network according to claim 1,
A radio resource control unit that performs radio resource allocation processing to the mobile station to communicate and monitors the allocation status;
Based on the measurement result report message notified from each of the mobile stations that are actually connected, another radio base station corresponding to an adjacent radio base station having an overlapping cover area for the mobile station is identified. A measurement result acquisition unit
For each other radio base station identified by the measurement result acquisition unit, a load information management unit that calculates the base station load overlap usage rate and the base station load total usage rate from the monitoring result by the radio resource control unit,
Information including the other radio base station specified by the measurement result acquisition unit, the base station load overlapping usage rate calculated by the load information management unit, and the base station load total usage rate as base station statistical information A statistical information generator for generating and notifying the control station;
With
The radio resource control unit
When the radio parameter notification message is notified from the control station as the first radio base station, a mobile station to be handed over to the second radio base station is specified based on the radio parameter notification message. A radio base station that performs the load distribution. In the radio base station according to claim 2,
The statistical information generation unit
When the base station load total usage rate calculated by the load information management unit is less than a preset third threshold, the base station statistical information is generated as information not including the base station load overlap usage rate, Radio base station that notifies the control station. A control station applied to the mobile communication network according to claim 1,
A statistical information acquisition unit that acquires the base station statistical information notified from each of the plurality of radio base stations;
Based on the base station statistical information notified from each of the plurality of wireless base stations acquired by the statistical information acquisition unit, the wireless base station that has notified the largest base station load total usage rate is the first wireless base station When the total base station load usage rate in the first radio base station is greater than a preset first threshold, the base station statistical information notified from the first radio base station Based on this, the adjacent radio base station having the highest base station load overlap usage rate for the first radio base station is further specified as a second radio base station, and the total base station load usage rate in the second radio base station is If it is smaller than the preset second threshold value, a radio parameter notification mem- ber for handing over the mobile station to the first radio base station with the second radio base station. And load balancing control unit for commanding to generate sage,
Based on a command from the load distribution control unit, the radio parameter generation unit generates the radio parameter notification message and notifies the first radio base station of the radio parameter notification message;
A control station comprising: A mobile station,
A plurality of radio base stations that communicate with the mobile station when connected to one or more mobile stations present in the coverage area to be provided;
A mobile communication network comprising:
The plurality of radio base stations are one radio base station with a central control function having a function of controlling overall load distribution of all the radio base stations, and one unit having no function of controlling the load distribution. Consists of the above wireless base station without overall control function,
The mobile station
For all the radio base stations that are within the area where they can communicate, generate the measurement result report message as a result of measuring the radio signal level, notify the currently connected radio base station,
Each of the radio base stations without the overall control function is
For each other radio base station corresponding to an adjacent radio base station having an overlapping cover area for the mobile station based on the measurement result report message notified from each of the mobile stations that are actually connected , Calculate the base station load overlap usage rate, and the base station load total usage rate, notify the radio base station with overall control function as base station statistical information,
The radio base station with overall control function is:
For each other radio base station corresponding to an adjacent radio base station having an overlapping cover area for the mobile station based on the measurement result report message notified from each of the mobile stations that are actually connected , Calculate the base station load overlap usage rate, and base station load total usage rate, generate base station statistical information,
Based on the base station statistical information generated by itself and the base station statistical information notified from each of the radio base stations without the overall control function, the radio base station that has notified the largest base station load total usage rate Is identified as the first radio base station, and when the total base station load usage rate in the first radio base station is greater than a preset first threshold, the first radio base station is notified. Based on the base station statistical information, the adjacent radio base station having the highest base station load overlap usage rate for the first radio base station is further specified as a second radio base station, and the base station in the second radio base station When the station load total usage rate is smaller than a preset second threshold, the mobile station is handed over to the first radio base station with the second radio base station. Notifies the line parameter notification message,
The first radio base station is
A mobile communication network that identifies a mobile station to be handed over to the second radio base station based on the radio parameter notification message notified from the radio base station with overall control function, and performs load distribution. A radio base station applied to the mobile communication network according to claim 5,
A radio resource control unit that performs radio resource allocation processing to the mobile station to communicate and monitors the allocation status;
Based on the measurement result report message notified from each of the mobile stations that are actually connected, another radio base station corresponding to an adjacent radio base station having an overlapping cover area for the mobile station is identified. A measurement result acquisition unit
For each other radio base station identified by the measurement result acquisition unit, a load information management unit that calculates the base station load overlap usage rate and the base station load total usage rate from the monitoring result by the radio resource control unit,
Generates information including the other radio base station specified by the measurement result acquisition unit, the base station load overlapping usage rate calculated by the load information management unit, and the base station load total usage rate as base station statistical information And a statistical information generation unit that notifies the radio base station with overall control function,
With
The radio resource control unit
When the radio parameter notification message is notified from the radio base station with overall control function as the first radio base station, a handover with the second radio base station should be performed based on the radio parameter notification message A radio base station that identifies a mobile station and performs load distribution. A mobile station,
A plurality of radio base stations that communicate with the mobile station when connected to one or more mobile stations present in the coverage area to be provided;
A mobile communication network comprising:
The mobile station
For all the radio base stations that are within the area where they can communicate, generate the measurement result report message as a result of measuring the radio signal level, notify the currently connected radio base station,
Each of the plurality of radio base stations
For each other radio base station corresponding to an adjacent radio base station having an overlapping cover area for the mobile station based on the measurement result report message notified from each of the mobile stations that are actually connected , Base station load overlap usage rate, and base station load total usage rate are calculated and notified to each of the plurality of radio base stations other than itself as base station statistical information, and the base station statistical information generated by itself and itself Based on the base station statistical information notified from each of the plurality of radio base stations other than the above, the mobile station identifies itself as a first radio base station, and the base station load total usage rate calculated by itself is set in advance. If it is greater than the first threshold, the adjacent radio base station having the largest base station load overlap usage rate for itself is further specified as the second radio base station, and the second radio base station If the total load utilization of the base station is less than a preset second threshold value, a mobile communication network that specifies a mobile station to be handed over with the second radio base station and performs load distribution . A radio base station applied to the mobile communication network according to claim 7,
A radio resource control unit that performs radio resource allocation processing to the mobile station to communicate and monitors the allocation status;
Based on the measurement result report message notified from each of the mobile stations that are actually connected, another radio base station corresponding to an adjacent radio base station having an overlapping cover area for the mobile station is identified. A measurement result acquisition unit
For each other radio base station identified by the measurement result acquisition unit, a load information management unit that calculates the base station load overlap usage rate and the base station load total usage rate from the monitoring result by the radio resource control unit,
Generates information including the other radio base station specified by the measurement result acquisition unit, the base station load overlapping usage rate calculated by the load information management unit, and the base station load total usage rate as base station statistical information And a statistical information generation unit that notifies each of the plurality of radio base stations other than itself,
With
The radio resource control unit
Based on the base station statistical information generated by itself and the base station statistical information notified from each of the plurality of radio base stations other than itself, the mobile station identifies itself as a first radio base station, When the base station load total usage rate is larger than a preset first threshold, the adjacent radio base station having the highest base station load overlapping usage rate for itself is further specified as a second radio base station, When the total base station load usage rate in the second radio base station is smaller than a preset second threshold, a mobile station to be handed over with the second radio base station is specified, and load distribution is performed A wireless base station. A mobile station,
A plurality of radio base stations that communicate with the mobile station when connected to one or more mobile stations present in the coverage area to be provided;
A control station that communicates with the plurality of radio base stations and performs overall control of load distribution of the plurality of radio base stations;
A load balancing control method executed in a mobile communication network comprising:
In the mobile station,
Including a step of generating a result of measuring a radio signal level as a measurement result report message for all the radio base stations existing within a communicable area and notifying the radio base station that is actually connected;
In each of the plurality of radio base stations,
For each other radio base station corresponding to an adjacent radio base station having an overlapping cover area for the mobile station based on the measurement result report message notified from each of the mobile stations that are actually connected Calculating a base station load overlap usage rate and a base station load total usage rate, and notifying the control station as base station statistical information,
In the control station,
Based on the base station statistical information notified from each of the plurality of wireless base stations, the wireless base station that has notified the largest total base station load usage rate is identified as the first wireless base station, and the first wireless base station When the base station load total usage rate in the base station is larger than a preset first threshold, the first radio base station is based on the base station statistical information notified from the first radio base station. The adjacent radio base station having the largest base station load overlap usage rate for the station is further specified as the second radio base station, and the total base station load usage rate in the second radio base station is set to a second threshold value set in advance. If not, a step of notifying the first radio base station of a radio parameter notification message for performing handover of the mobile station with the second radio base station Look,
In the first radio base station,
A load distribution control method comprising: specifying a mobile station to be handed over with the second radio base station based on the radio parameter notification message notified from the control station, and performing the load distribution.

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