JP2011035763A - Load distribution method and radio base station control apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain improvement of cell throughput by relaxing eccentricity in sector load since it may be possible to reduce throughput as an entire cell when there is eccentricity in load among sectors within the same cell. <P>SOLUTION: A base station control apparatus periodically obtains the amount of use of each sector in each radio base station and if the amount of use exceeds a threshold, a radio terminal is handed over from a sector with the amount of use exceeding the threshold to a sector with the lower amount of use, thereby reducing the amount of use. Furthermore, if the radio terminal attempts a connection to the sector with the amount of use exceeding the threshold and there are any other sectors receiving radio waves than the sector to which the terminal attempts the connection, processing for performing the connection using a sector with a highest reception strength among the sectors is performed. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a load distribution method and a radio base station control apparatus in a radio communication system, and more particularly to a load distribution method and radio base station control apparatus for performing handover control between radio base stations having a plurality of sectors.

  Mobile communication is based on the fact that a radio terminal such as a mobile phone or PHS finds radio waves from the nearest radio base station and exchanges radio waves between the radio terminal and the radio base station. A communicable range in which radio waves reach from one or more antennas provided in the radio base station is called a sector. The radio base station includes one or a plurality of sectors.

  A mobile communication service area is configured by arranging sectors without gaps. By adopting a multi-sector configuration in which wireless base stations are installed at certain distance intervals, and laying out multiple sectors provided by each base station without interruption, wireless terminals can communicate from anywhere, Service area is established.

  In addition, since the mobile phone or PHS may be moved during communication, communication paths are switched between a plurality of radio base stations. This is generally called handover (or handoff). With handover, communication during movement can be performed without interruption.

  Patent Document 1 discloses a technique for performing load distribution so that a difference occurs in the load at each radio base station due to handover, and a high load is not applied to a specific radio base station. In the technique disclosed in Patent Document 1, in order to reduce the load of the own radio base station (hereinafter referred to as the own station), the load information of the adjacent radio base station is periodically acquired, and the load of the own station is predetermined. When the threshold value is exceeded, an adjacent radio base station with the lowest load is selected which is a radio base station capable of distributing the load of the own station based on the load information. The own radio base station hands over to the radio base station a radio terminal whose reception level is the next highest next to the own base station.

JP 2008-2111645 A

  However, the technique of Patent Document 1 makes an inquiry to a wireless terminal device corresponding to movement when a base station to which load distribution is performed is triggered by the load state (high load) of the own station. Moreover, the load information of an adjacent radio base station is also acquired periodically. For this reason, rapid load distribution control cannot be performed in an environment with a load state and a reception level that change every moment.

  In addition, even if there are one or a plurality of terminals that have selected adjacent radio base stations with a low load as a handover destination, handover is performed collectively. For this reason, there is a possibility that the adjacent radio base station of the handover destination will fall into a high load state. Furthermore, since one wireless base station having a plurality of sectors is not considered, load distribution within the same wireless base station is not mentioned.

In a radio communication system, when one radio base station has a plurality of sectors, one sector of one radio base station has a high load, while the other sector has a light load, In some cases, it is not used, and effective utilization of radio resources is required.
The present invention provides a load distribution method and a radio base station controller that can effectively use radio resources.

  In order to achieve the above object, the radio base station control device of the present invention obtains reception strength information for each sector from the radio terminal at the time of a connection request from the radio terminal, and periodically receives the reception strength information and the received strength information. A sector to which a wireless terminal is connected is selected based on the load information for each sector from the wireless base station (number of wireless terminals used, data traffic volume information, etc.).

  Further, even when a handover request is made from a wireless terminal, the reception strength information for each sector is acquired from the wireless terminal, and the reception strength information and the load information for each sector from a plurality of wireless base stations that are periodically acquired are obtained. Then, the sector to which the wireless terminal is connected by handover is selected.

  Furthermore, even when the wireless terminal is connected, if the load information for each sector from a plurality of wireless base stations acquired periodically exceeds a predetermined threshold in the sector used by the wireless terminal, Handover is performed to a candidate sector for handover to be registered.

  The purpose described above is to receive a connection request from the first radio terminal via the first radio base station, to obtain load information from the plurality of radio base stations, and from the first radio terminal. Obtaining the reception strength information of the first wireless terminal via the first wireless base station, and selecting a second wireless base station to which the first wireless terminal can be connected based on the load information and the reception strength information And a step of registering a second radio base station to which the first radio terminal can be connected based on the selection result.

  Receiving a handover request from the first wireless terminal via the first wireless base station; obtaining load information for each sector from the plurality of wireless base stations; A step of obtaining reception strength information for each sector of the first wireless terminal via one wireless base station, and a second sector capable of performing handover connection of the first wireless terminal based on the load information and the reception strength information And a step of registering a second sector that can be handed over to the first wireless terminal based on the load information and the received strength information.

  Furthermore, means for receiving a connection request from the first wireless terminal via the first wireless base station, means for acquiring load information for each sector from the plurality of wireless base stations, and Means for acquiring reception strength information for each sector of the first wireless terminal via one wireless base station, and a second sector to which the first wireless terminal can be connected based on the load information and the reception strength information This can be achieved by a radio base station controller having means for selecting and means for registering a second sector to which a radio terminal can be connected based on the selection result.

  ADVANTAGE OF THE INVENTION According to this invention, the load distribution method and radio | wireless base station control apparatus which can use radio | wireless resource effectively can be provided.

It is a figure explaining the sector structure of a base station. It is a block diagram explaining the system configuration | structure of a radio | wireless communications system. It is a functional block diagram of a base station control apparatus. It is a hardware block diagram of a base station control apparatus. It is a functional block diagram of a radio base station. It is a reception intensity table with which a base station control apparatus is provided. It is a usage-amount information table with which a base station control apparatus is provided. It is a receiving terminal information table with which a base station control apparatus is provided. It is a connection management table with which a base station control apparatus is provided. It is a sector selection flow chart at the time of a call connection request from a wireless terminal in the base station controller. It is a sector selection flow chart at the time of a handover request from a radio terminal in the base station control device. FIG. 6 is a forcible handover flow diagram when a wireless terminal in a base station control device is communicating. It is a forced handover operation | movement sequence diagram in a radio | wireless communications system.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings using examples. The same reference numerals are assigned to substantially the same parts, and the description will not be repeated.

  First, the sector configuration of the wireless communication system will be described with reference to FIG. In FIG. 1, a radio base station 100 that communicates with a radio terminal 50 has three sectors. Here, the three sectors are called α, β, and γ in the clockwise direction from 12 o'clock. The radio base station 100 transmits and receives signals to and from the radio terminal 50 via the sector.

  The system configuration of the wireless communication system will be described with reference to FIG. In FIG. 2, a radio communication system 300 includes six radio base stations 100 (hereinafter also referred to as BS1 to BS6), a base station controller 200 that controls each radio base station 100, and a large number of radio terminals 50. It consists of. A circle centering on each radio base station 100 indicates an area where radio waves reach. A large number of black dots indicate the wireless terminal 50. Note that the description of the sectors described with reference to FIG. 1 is omitted here. Base station control apparatus 200 is connected to radio base station 100 by wire. On the other hand, the wireless terminal 50 is wirelessly connected to the wireless base station 100.

  The configuration of the base station control device will be described with reference to FIG. In FIG. 3, the base station control device 200 includes a base station control unit 210 and a line interface (line IF) 240. The base station control unit 210 includes a call processing control unit 230 and a memory 220. Further, the memory 220 stores a reception strength table 221, a usage information table 222, a reception terminal information table 223, a connection management table 224, a call control information database 225, and a call processing control program 226.

  The base station control unit 210 is operated by a call processing control program 226 stored in advance in the memory 220. The reception strength table 221 collectively includes the wireless terminals 50 managed by the base station control unit 210. The call control information database 225 stores detailed connection information (pilot signal information, frequency channel information, connection time, etc.) of the wireless terminal 50 managed by the base station control unit 210. The call processing control unit 230 performs control related to wireless communication.

  The hardware configuration of the base station control device will be described with reference to FIG. In FIG. 4, the base station control device 200 includes a CPU 250, a memory 220, a storage device 270, and a plurality of line IFs 241 interconnected by an internal bus 280. The CPU 250 executes the call processing control program 226 stored in the memory 220, uses the various tables 221 to 224 stored in the storage device 270 and copied to the memory 220, and the base station control unit 210 as a whole and the base station The radio base station 100 connected to the control unit 210 is controlled.

  These units described above are connected by the internal bus 280, and control to the radio base station 100 is performed via the line IF 241. Note that the tables 221 to 224 in FIG. 3, the call control information database 225, and the like can be stored in the memory 220 or the storage device 270. The call processing control unit 230 is realized by the CPU 250 executing the call processing control program 226.

  The configuration of the radio base station will be described with reference to FIG. In FIG. 5, the radio base station 100 includes a device control unit 110, a line IF 120, and a plurality of sector control units 130 that are interconnected by an internal bus 150. The sector control unit 130 is connected to the antenna 140. The sector control unit 130 is described as sector control unit 130-α, sector control unit 130-β, and sector control unit 130-γ for each sector. The antenna 140 is also described in the same way when distinguishing.

  The device control unit 110 includes a CPU 111, a memory 112, and a storage device 113 that are interconnected by an internal bus 114. The device control unit 110 controls the entire radio base station 100. The sector control units 130-α to 130-γ of each sector have a wireless IF 131 and a communication process 132. The CPU 111 of the device control unit 110 controls the entire radio base station 100 using the control program stored in the memory 112 and various data (such as information on the wireless terminal) stored in the storage device 113. The sector control units 130-α to 130-γ perform transmission of control messages transmitted from the sectors and reception processing of various control messages from the wireless terminal 50. The above units and the like are connected by an internal bus 150, and communication with the base station control unit 210 is performed through the line IF 120.

  With reference to FIG. 6, the reception intensity table stored in the base station control unit will be described. In FIG. 6, the reception strength table 221 includes a terminal ID 2211, a sector 2212, and a reception strength 2213. The content of the reception strength table 221 is information notified by the wireless terminal when a call connection request or a handover request is made. The reception strength table 221 manages the radio wave reception strength of each sector for each wireless terminal. The reception strength is the strength of the radio wave received by the wireless terminal 50 from the sector. In this embodiment, the radio wave strength is indicated by a numerical value from 0 to 63, and the smaller the value is, the higher the reception strength is. I am doing so.

  When the radio terminal 50 receives radio waves from a plurality of sectors at the time of a call connection request or the like, the radio terminal 50 performs a process of collectively transmitting reception intensity information of each sector. The base station control unit 210 registers the received information in the reception intensity table 221.

  FIG. 6 shows the reception strength table 221 when there are three wireless terminals (ac). Here, the wireless terminal a (terminal ID = a) portion of the reception strength table 221 will be described. Among the reception strengths of the wireless terminal a, the sector with the strongest reception strength is BS1-α (BS1 α sector), which has a radio wave intensity of 10, followed by BS1-β (radio wave intensity of 15), BS2-γ (radio wave intensity of 20 ), BS2-α (radio wave intensity 30), BS2-β (radio wave intensity 35), BS1-γ (radio wave intensity 40).

  With reference to FIG. 7, a usage information table held by the base station controller will be described. In FIG. 7, the usage amount information table 222 includes a sector 2221 and a usage amount 2222. The usage information table 222 is a table for managing the usage of each sector in the base station managed by the base station controller 200. That is, the usage amount information table 222 centrally manages the usage amount of each base station sector.

  The amount used here is the number of connected wireless terminals or the amount of traffic used by wireless terminals. The larger the value, the higher the load. In the case of FIG. 7, it can be seen that the sector with the highest usage is BS1-α with a usage of 200.

  With reference to FIG. 8, the receiving terminal information table which a base station control part hold | maintains is demonstrated. In FIG. 8, the receiving terminal information table 223 includes a sector 2231 and a terminal ID 2232. The receiving terminal information table 223 is a radio that corresponds to a candidate destination for forcibly handing over when the communication load of a sector to be used (during call connection) or a sector in use (during communication) increases. It is a table which registers terminal information.

  The wireless terminal (terminal ID 2232) registered for each sector 2231 in the receiving terminal information table 223 has a sector usage load equal to or lower than a predetermined threshold and has a reception strength to the wireless terminal other than the connected sector. It is registered in the strongest sector. The receiving terminal information table 223 is referred to when a radio terminal to be handed over is selected when the sector communication load is high.

  With reference to FIG. 9, the connection management table which a base station control part hold | maintains is demonstrated. In FIG. 9, the connection management table 224 includes a sector 2241 and a terminal ID 2242. The connection management table 224 is a table for managing which sector is used by the wireless terminal for each sector of the base station managed by the base station control apparatus 200. Specifically, the second record indicates that the wireless terminals a and b are connected to the BS 1-β for communication. The connection management table 224 is created from information extracted from the call control information database 225. At the same time as the call control information database 225 is updated, the connection management table 224 is also updated.

With reference to FIG. 10, a sector selection process at the time of a call connection request from a wireless terminal in the base station control device will be described. Specifically, a method for dispersing the usage amount will be described.
The base station control unit 210 acquires the usage amount of each sector from the plurality of radio base stations 100 at a predetermined cycle (S101). The base station control unit 210 stores the usage information in the usage information table 222 (S102).

  When the base station control unit 210 receives the connection request from the wireless terminal 50 via the wireless base station 100 (S103), the base station control unit 210 stores the reception strength information transmitted together with the call connection request from the wireless terminal 50 in the reception strength table 221. Store (S104). The base station control unit 210 selects a sector having the strongest reception strength from the reception strength table 221 as a sector to be used by the wireless terminal 50 that has requested connection (S105).

  Next, the base station control unit 210 refers to the usage amount of the sector selected in step 105 from the usage amount information table 222, and determines whether it is equal to or less than a predefined threshold value (S106). As a result of this determination, when the threshold value is exceeded (NO), the base station control unit 210 checks the presence / absence of a sector having the next strongest reception intensity from the reception intensity table 221. (S107). Here, if there is a sector with the next strongest reception strength in the reception strength table 221, the base station control unit 210 selects the sector (S108), and proceeds to step 106. In step 107, if there is no sector with the next strongest reception strength, the base station control unit 210 maintains the selection of the current sector (a sector with high reception strength but a crowded usage amount equal to or greater than the threshold) ( S109). The base station control unit 210 performs call connection processing in the sector (S110). Moreover, in the case of YES in step 106, the base station control unit 210 proceeds to step 110 as it is.

  The base station control unit 210 determines whether there is a sector other than the selected sector whose usage amount is equal to or less than a threshold and whose reception strength is strongest (S111). When there is no corresponding sector, the base station control unit 210 ends as it is. When there is a corresponding sector in step 111, the base station control unit 210 stores the terminal ID in the record of the corresponding sector in the receiving terminal information table 223 (S112), and the process ends.

  In step 107, the sector selection is performed by giving priority to the radio wave reception strength over the sector usage amount. However, the sector usage amount may be prioritized over the radio wave reception strength. The usage amount may be compared with a predetermined threshold value so that a medium amount is selected.

  The case where there is no selectable sector in S107 is, for example, the case where only one sector is stored in the reception intensity table, or the case where the usage amount of all the stored sectors exceeds the threshold. is there. In such a case, the sector selection is performed with priority given to the reception strength rather than the sector usage, and the call connection process is performed.

  Here, a specific operation with the terminal a will be described with reference to the reception strength table 221 shown in FIG. Base station control section 210 selects BS1-α having the strongest reception strength. Assuming that the threshold value for the usage amount is 100, BS1-α is “200” from the usage amount information table 222 of FIG. For this reason, the base station control unit 210 selects BS1-β, which is the sector having the next strongest reception intensity, from the reception intensity table 221. According to FIG. 7, the usage amount of BS1-β is “40”, which is equal to or less than the threshold value of 100, so that the call connection processing is performed by BS1-β.

  Since the sector selected for connection by the wireless terminal a is BS1-β, it is a sector other than BS1-β in the reception table 221 for the terminal a in FIG. Sectors below the threshold are selected. In this case, since the sector that matches the condition is BS2-γ, the base station control unit 210 associates with the BS2-γ sector of the receiving terminal information table 223 in FIG. Register.

With reference to FIG. 11, a sector selection process at the time of a handover request from a radio terminal in the base station control apparatus will be described. Specifically, a method for dispersing the usage amount will be described.
The base station control unit 210 acquires the usage amount of each sector from the plurality of radio base stations 100 at a predefined cycle (S201). The base station control unit 210 stores the usage amount information in the usage amount information table 222 (S202). When the base station control unit 210 receives the handover request from the radio terminal 50 via the radio base station 100 (S203), the base station control unit 210 stores the reception strength information transmitted together with the handover request from the radio terminal 50 in the reception strength table 221. (S204). The base station control unit 210 selects the sector having the strongest reception strength from the reception strength table 221 as the sector to be used by the wireless terminal 50 that has requested connection (S205).

  Next, the base station control unit 210 refers to the usage amount of the sector selected in S105 from the usage amount information table 222, and determines whether it is equal to or less than a predefined threshold value (S206). If the threshold is exceeded as a result of this determination, the base station control unit 210 checks the presence / absence of a sector having the next strongest reception strength from the reception strength table 221 (S207).

  Here, if there is a sector with the next strongest reception strength in the reception strength table 221, the base station control unit 210 selects the sector (S208), and proceeds to step 206. Next, when there is no sector with strong reception strength, the base station control unit 210 maintains the selection of the current sector (sector with high reception strength but crowded usage amount equal to or greater than the threshold) (S209).

  When YES in step 206 and after step 209, the base station control unit 210 performs a handover process in the selected sector (S210). The base station control unit 210 determines whether or not there are sectors other than the selected sector whose usage amount is equal to or less than a threshold and whose reception strength is strongest (S211). When there is no corresponding sector, the base station control unit 210 ends as it is. When there is a corresponding sector in step 111, the base station control unit 210 stores the terminal ID in the record of the corresponding sector in the receiving terminal information table 223 (S212), and the process ends.

  In step 207, sector selection is performed by giving priority to radio wave reception intensity over sector usage, but sector usage may be prioritized over radio wave reception intensity. The usage amount may be compared with a predetermined threshold value so that a medium amount is selected.

With reference to FIG. 12, the forced handover process when the wireless terminal is communicating in the base station control apparatus will be described. Specifically, a method for dispersing the usage amount will be described.
The base station control unit 210 acquires the usage amount of each sector from the plurality of radio base stations 100 at a predetermined cycle (S301). The base station control unit 210 stores the usage amount information in the usage amount information table 222 (S302).

  Next, the base station controller 210 determines whether or not the usage amount of each sector stored in the usage amount information table 222 is equal to or less than a predetermined threshold (S303). When there is one or more sectors exceeding the predetermined threshold, the base station control unit 210 selects the sector with the highest usage amount among them (S304). The base station control unit 210 extracts terminal information stored in association with the selected sector from the connection management table 224 (S305). This specifies a wireless terminal that is communicating using a sector with a large amount of usage.

  Next, the base station control unit 210 selects the sector with the lowest usage amount from the usage amount information table 222 (S306). The base station control unit 210 extracts terminal information stored in a sector with a low usage amount from the receiving terminal information table 223 (S307). This is for specifying a radio terminal that uses a sector with a small amount of use as a handover candidate.

  The base station control unit 210 compares the terminal IDs extracted in step 305 and step 307 and determines whether or not they match (S308). If there is matching terminal information (YES), the base station control unit 210 forcibly hands over the corresponding wireless terminal to a sector with low usage (S309). In short, let a wireless terminal using a sector with a large amount of usage use a free sector with a small amount of usage, which is a handover destination narrowed down in advance, and load distribution in the wireless communication system is just-in-time. Do.

  Next, the base station control unit 210 deletes the terminal information of the wireless terminal that has been handed over from the receiving terminal information table 223 (S310), and transitions to step 303.

  If there is no matching terminal information in step 308, the base station control unit 210 checks the presence / absence of the sector with the next lowest usage amount from the usage amount information table 222 (S311). Here, if there is a sector with the next lowest usage, the base station control unit 210 selects the sector (S312), and proceeds to step 307. In step 303, if there is no sector exceeding the predetermined threshold, the base station control unit 210 ends as it is.

  In step 304, the sector having the highest sector usage is selected. However, the present invention is not limited to this, and one of the sectors having the usage more than the threshold may be selected. . In step 306, the sector having the lowest sector usage is selected. However, the present invention is not limited to this, and one of the sectors having the usage less than the threshold may be selected. In step 311, the sector having the next lowest sector usage is selected. However, the sector is not limited to this. The sector other than the sector compared in step 308 has a usage amount equal to or lower than the threshold value. Select one of the existing sectors.

  Here, a specific operation will be described on the assumption that the tables 221 to 224 stored in the base station control unit 210 are in the state shown in FIGS. In this case, the base station control unit 210 determines that BS1-α exceeds the threshold value. The base station control unit 210 extracts d, e, w, k, r, and t stored in the terminal information of BS1-α from the connection management table 224. Next, the base station control unit 210 selects the BS2-γ having the lowest usage amount from the usage amount information table 222, and a, w, stored in the terminal information of BS2-γ in the receiving terminal information table 223 r is extracted.

  At this time, the usage amount of the selected sector needs to be equal to or less than a threshold value. Base station control section 210 compares terminal information extracted by each. As a result, the base station control unit 210 extracts w and r. One terminal information is selected from the handover destination candidates. As a method of selecting one terminal information from among handover candidates, a method of selecting terminal information that matches first, a method of selecting terminal information having the strongest reception strength at the handover destination, and the like are assumed. Here, a method of selecting terminal information that matches first is used.

  Here, when w is selected, the base station control unit 210 hands over the radio terminal w to BS2-γ. After the handover, the base station control unit 210 deletes the terminal information of the wireless terminal w that has been handed over from the receiving terminal information table 223. After the handover process, it is determined again whether the usage is below the threshold. Here, it is assumed that the usage amount of BS1-α exceeds the threshold even if the wireless terminals w and r are handed over. The base station control unit 210 is in a state where there is no handover candidate terminal information in BS2-γ of the receiving terminal information table 223. Therefore, BS3-α which is the sector with the next lowest usage amount is selected from the usage amount information table 222, and the processing is continued from step 307. At this time, the usage amount of the selected sector needs to be equal to or less than a threshold value. If there are no selectable sectors from the usage information table, the process is terminated.

  A forced handover operation sequence in the wireless communication system will be described with reference to FIG. In FIG. 13, the radio terminal 50 performs communication using the radio base station 100-1 (BS1-α sector), the BS1-α sector is in a high load state, and the radio base station 100- with a small amount of use is shown. 2 (BS2-γ sector) is a forced handover sequence.

  In FIG. 13, a radio terminal 50 performs communication using a radio base station 100-1 (BS1-α sector). The radio base station 100-1 and the adjacent base station 100-2 (same for a plurality of radio base stations other than 100-2) periodically transmit a usage information notification message to the base station control device 200, The own station is notified of the degree of congestion (S401, S402).

  Receiving the usage information notification message, the base station control apparatus 200 acquires the usage for each sector of each radio base station 100 and stores it in the usage information table 222 (S403).

  Next, it is determined whether or not the usage amount of each sector exceeds the predetermined threshold value based on the acquired usage amount information (S404). If all sectors are within the threshold value, the radio base station 100-1 (BS1- Communication using (α sector) is continued.

  Here, the communication load at the radio base station 100-1 (BS1-α sector) becomes high (S406). The radio base station 100-1 and the adjacent base station 100-2 periodically transmit a usage information notification message to the base station control apparatus 200 to notify the congestion level of the own station (S407, S408). ).

  Receiving the usage information notification message, the base station controller 200 acquires the usage for each sector of each radio base station 100 and stores it in the usage information table 222 (S409).

  Next, it is determined whether or not the usage amount of each sector exceeds a predetermined threshold based on the acquired usage amount information (S410). In this case, since the usage information acquired by the usage information notification message (S407) received from the radio base station 100-1 (BS1-α sector) exceeds the threshold value, the base station control apparatus 200 is configured as shown in FIG. The handover destination of the radio terminal 50 is determined according to the operation flowchart (S411).

  Then, a handover request message including the determined handover destination information (radio base station 100-2 (BS2-γ sector) information) is transmitted to the radio terminal 50 via the radio base station 100-1 (BS1) (S412).

  The radio terminal 50 that has received the handover request message executes a handover to the radio base station 100-2 (BS2-γ sector) (S413). The radio terminal 50 transmits a handover completion message to the radio base station controller 200 via the radio base station 100-2 (BS2) (S414).

The wireless terminal 50 is now in a state of performing communication using the wireless base station 100-2 (BS2-γ sector). Since this state is a state in which the communication path between the radio base station controller 200 and the radio base station 100-1 (BS1-α sector) continues, it is necessary to disconnect the call path. Therefore, the base station control apparatus 200 transmits a disconnection request message to the radio base station 100-1 (BS1) (S416). The radio base station 100-1 (BS1) that has received the disconnection request message transmits a disconnection completion message to the base station control device 200 (S417).
In the above-described embodiment, the number of sectors included in the radio base station 100 is described as 3. However, the present invention can also be applied to radio base stations having other (1 or more) sector configurations.

  According to the present embodiment, the second connection destination of the wireless terminal (one of a plurality of sectors under the base station or the base station) is registered in advance at the time of the connection request of the wireless terminal. When the load becomes higher than the threshold, it is possible to immediately hand over to the second connection destination.

  Even when a wireless terminal is moved by handover, the second connection destination is registered even at the handover destination. Therefore, when the connection destination is in a higher load state than a predetermined threshold as described above, Can be handed over to the second connection destination.

  In addition, since the terminals selected with the adjacent radio base station having a low load as the handover destination are handed over one by one, there is no fear that the adjacent radio base station at the handover destination suddenly falls into a high load state. Load distribution can be performed.

  In addition, since a configuration in which one radio base station has a plurality of sectors is considered, it is possible to perform handover between sectors in one radio base station as well as simply changing the radio base station at high load. It becomes. This leads to preventing one sector of one radio base station from being overloaded and handing over to another radio base station even if the other sector is empty. And, by selecting the handover destination in units of sectors, not in units of radio base stations, even when the radio base station is not a neighboring station, a radio base station that can receive radio waves even a little This sector can be the next handover destination (at the time of high load), and radio resources can be effectively used.

Furthermore, registering candidate sectors for handover in advance means that load information and reception strength information are included in order to distribute the load in the wireless communication system by forcibly handing over the wireless terminal in a predetermined communication environment. Based on this, candidate sectors for handing over the wireless terminal are registered in advance, and the wireless terminal can be smoothly moved between sectors. In addition, the registration operation (candidate sector update operation) is appropriately performed at the time of call connection request from the wireless terminal, at the time of handover request, and the like, even in a constantly changing communication environment, a good handover destination at that time Can be specified and selected.
In the above-described embodiments, the radio base station control device is installed separately from the radio base station, but a configuration in which the function of the radio base station control device is built in a predetermined radio base station may be employed.

  DESCRIPTION OF SYMBOLS 50 ... Wireless terminal, 100 ... Wireless base station, 110 ... Apparatus control part, 130 ... Sector control part, 131 ... Wireless IF unit, 132 ... Communication processing unit, 140 ... Antenna, 200 ... Base station control apparatus, 210 ... Base station Control unit, 220 ... memory, 221 ... reception intensity table, 222 ... usage amount information table, 223 ... reception terminal information table, 224 ... connection management table, 225 ... call control information database, 230 ... call processing control unit, 241 ... line IF unit, 250 ... CPU, 270 ... storage device, 280 ... internal bus.

Claims (6)

In a load distribution method in a radio communication system including a plurality of radio terminals, a plurality of radio base stations, and a radio base station control device,
Receiving a connection request from a first wireless terminal via a first wireless base station;
Obtaining load information from the plurality of radio base stations;
Obtaining reception intensity information of the first wireless terminal from the first wireless terminal via the first wireless base station;
Selecting a second radio base station to which the first radio terminal can be connected based on the load information and the received strength information;
Registering the second radio base station to which the first radio terminal can be connected based on a selection result;
A load distribution method comprising: The load distribution method according to claim 1,
The radio base station has a plurality of sectors,
The load information and the reception strength information are the load information and the reception strength information for each of the plurality of sectors,
The load distribution method according to claim 1, wherein the registering step is a step of registering a specific sector of the second radio base station. A load distribution method in a wireless communication system including a plurality of wireless base stations, a plurality of wireless base stations having sectors, and a wireless base station controller,
Receiving a handover request from a first wireless terminal via a first wireless base station;
Obtaining load information for each sector from the plurality of radio base stations;
Obtaining reception intensity information for each sector of the first wireless terminal from the first wireless terminal via the first wireless base station;
Selecting a second sector that can be handed over to the first wireless terminal based on the load information and the received strength information;
Registering the second sector that can be handed over to the first wireless terminal based on the load information and the received strength information;
A load distribution method comprising: Obtaining connected wireless terminal information for each sector from the plurality of wireless base stations;
A first comparison step of comparing the wireless terminal information for each sector with a predetermined threshold;
Extracting at least one sector having the largest number of wireless terminals and a sector having the smallest number of wireless terminals from the wireless terminal number information when there is at least one sector equal to or greater than a threshold in the first comparison step; ,
A second comparison step of comparing a wireless terminal connected to a sector having the largest number of extracted wireless terminals and a wireless terminal having the sector having the largest number of extracted wireless terminals as the second sector candidate When,
If there is a matching terminal in the second comparison step, instructing handover of one of the corresponding terminals to the second sector candidate;
The load distribution method according to claim 2, wherein: Means for receiving a connection request from the first wireless terminal via the first wireless base station;
Means for obtaining load information for each sector from a plurality of radio base stations;
Means for obtaining reception intensity information for each sector of the first wireless terminal from the first wireless terminal via the first wireless base station;
Means for selecting a second sector to which the first wireless terminal can be connected based on the load information and the received strength information;
Means for registering the second sector to which the wireless terminal can be connected based on a selection result;
A radio base station control device comprising: Means for acquiring information on connected wireless terminals for each sector from the plurality of wireless base stations;
First comparing means for comparing the wireless terminal information for each sector with a predetermined threshold;
Means for extracting a sector having the largest number of wireless terminals and a sector having the smallest number of wireless terminals from the wireless terminal number information when there is at least one sector equal to or greater than a threshold in the first comparison means; ,
Second comparison means for comparing a wireless terminal connected to a sector having the largest number of extracted wireless terminals and a wireless terminal having the sector having the largest number of extracted wireless terminals as the second sector candidate When,
Means for instructing handover of one of the corresponding terminals to the second candidate sector when there is a matching terminal in the second comparing means;
The radio base station control apparatus according to claim 5, comprising:

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