JP2010193278A - Mobile communication system, device for controlling the same, and method of creating database - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To smoothly execute handover transferring between control devices and improve high-speed movement performance without increasing cost. <P>SOLUTION: When inter-device handover straddling between base stations under different control devices occurs along with movement of a mobile terminal, pieces of adjacent base station information 44a are communicated between relevant base stations to integrate the pieces of the adjacent base station information to be stored by each of them are integrated. The respective control devices G11, G12 carry out handover estimation using the integrated adjacent base station information. Thereby, linkage between the control devices can be established, and high-speed handover can be achieved even for movement straddling between the control devices. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an improvement in a mobile communication system that forms an area by, for example, a microcell system. In particular, the present invention is a technique related to switching of a base station accompanying movement of a mobile terminal, so-called handover (also referred to as handoff).

  Methods for forming an area of a mobile communication system are roughly classified into a macro cell method and a micro cell method. A typical example of the former is a so-called mobile phone system, and each radio area has a radius of several kilometers. On the other hand, for example, the PHS (Personal Handy-phone System) in Japan adopts the latter method, and the area radius is very small, about several hundred meters at most.

  In the microcell system, base stations are frequently added and removed in response to changes in local communication demand. Under such circumstances, the base station is often installed on a per-field basis without a careful plan (also referred to as a station design) such as its installation position or a positional relationship with an adjacent base station. Interference between the resulting areas is avoided by each base station autonomously dealing with it.

  In this type of system, areas are switched by a re-call from a mobile terminal at the time of handover. In a microcell system, since handover frequently occurs, it is vulnerable to high-speed movement of terminals, and there is a need to solve this. However, since the performance of handover greatly depends on the capability of the terminal at present, the cost of the terminal rises when trying to improve the high-speed movement performance. Since this directly leads to an increase in the cost burden on the user, a countermeasure is required. For example, a method of predicting a destination base station has been conceptually proposed (see, for example, Patent Documents 1 and 2). In particular, a technique for speeding up handover using a database called adjacent base station information has been studied.

  By the way, instead of the conventional system in which each base station is directly connected to the network, a system configuration is considered in which a concentrator is provided and a plurality of base stations are connected to the network via this concentrator (for example, Patent Document 3). 4). The line concentrator accommodates individual base stations via individual lines and has various control functions such as health check of the base stations. This type of device is referred to as a base station control device or the like, and hereinafter abbreviated as a control device.

  However, the existing technology does not consider handover across control devices. In other words, there is no known technique that can smoothly realize handover from one control device to another control device, and this may cause a bottleneck and reduce the performance of the entire system.

JP-A-5-344559 Japanese Patent Laid-Open No. 11-103479 JP 2004-165906 A JP 2008-22309 A

As described above, in the existing mobile communication system, although an attempt has been made to improve the handover performance without increasing the cost of the terminal, a technique capable of speeding up the handover across control apparatuses is not known.
The present invention has been made in view of the above circumstances, and an object of the present invention is to make it possible to smoothly perform a handover that moves between control devices, thereby enabling high-speed movement performance to be improved at low cost, and its To provide a control device and a database creation method.

  In order to achieve the above object, according to one aspect of the present invention, a plurality of base stations that individually accommodate mobile terminals that each form a radio zone and perform handover between the radio zones, and the plurality of base stations are connected to individual channels. A plurality of control devices that are distributed and accommodated under their own control, wherein the plurality of control devices are connected to the mobile communication system for each permutation in which a plurality of base stations under its control are arranged. A construction means for constructing a database in association with the frequency of occurrence of the permutation in the history of the generated handover as the history is accumulated, and predicting the next handover destination base station of the mobile terminal in communication based on the frequency Prediction means, instruction means for instructing the mobile terminal in communication to perform handover to the predicted base station, a base station under its control, and a base station under the control of another control apparatus, When an inter-device handover occurs in which the mobile terminal makes a transition, the permutation including the base station under the control of the other control device and its frequency are added to the database and the database is integrated with the other control device. There is provided a mobile communication system comprising an integrated processing means.

  By taking such means, when an inter-device handover occurs across control devices, the database is integrated between the related control devices. More specifically, data including base station identification information before and after the handover and the time of the handover are exchanged between the related control apparatuses. These control devices join the data received from each other to their own local database, and an integrated database is created. Therefore, by using this database, it is possible to realize a high-precision and high-speed handover even for a handover across control devices.

  According to the present invention, a mobile communication system, a control device thereof, and a database creation method capable of smoothly performing a handover moving between control devices and thereby improving high-speed movement performance at a low cost are provided. be able to.

1 is a system diagram showing an embodiment of a mobile communication system according to the present invention. The functional block diagram which shows the control apparatuses G11 and G12 of FIG. The figure which shows an example of the database memorize | stored in the memory. The block diagram which shows the function with which the main-control part 45 of FIG. 2 is equipped. The figure which shows an example of the positional relationship of a base station. The figure which shows the detail of FIG. The sequence diagram which shows the procedure implemented between control apparatuses in the case of sharing adjacent base station information. The figure which shows an example of the adjacent base station information before integration. The figure which shows an example of the adjacent base station information after integration. The sequence diagram which shows an example of the process sequence in the inter-device handover prediction using the integrated adjacent base station information.

  FIG. 1 is a system diagram showing an embodiment of a mobile communication system according to the present invention. This system is formed with a communication network 100 and control devices G11 and G12 connected thereto as a core. The communication network 100 is, for example, a private network of a carrier, and specifically, a packet communication network such as an IP (Internet Protocol) network, an IP-VPN (IP-Virtual Private Network) connection service, or an ISDN (Integrated Service Digital Network). Etc. A gateway 200 is provided to connect the communication network 100 to the Internet 300. In addition, the communication network 100 is provided with a server device 400 for remotely controlling the control devices G11 and G12 and providing various communication services.

  The control device G11 accommodates the base station CS11 via an individual line. The control device G12 accommodates the base station CS12 via another individual line. That is, the base stations CS11 and CS12 are under the control of different control devices. Of course, each control device G11, G12 accommodates a plurality of base stations as well as the base stations CS11, CS12. That is, a plurality of base stations are distributed and accommodated in one of the control devices G11 and G12.

  Each base station including CS11 and CS12 forms a radio zone, and accommodates mobile terminals PS (PS11 and PS12) located in the radio zone via a radio channel. As the mobile terminals PS11 and PS12 move, they hand over each radio zone and switch the base station to which they are connected. The control devices G11 and G12 can also form a communication link between each other via the communication network 100, and the mobile terminals PS11 and PS12 can communicate with each other via this link. Furthermore, it is possible to access the Internet 300 via the gateway 200.

  In addition to this, the system of FIG. 1 is provided with a relay unit for connecting a personal computer (PC) or a fixed telephone (TEL) to the control devices G11 and G12. In particular, if voice call software is installed, a PC can be used as a telephone. Furthermore, an access point (not shown) compliant with a wireless LAN (Local Area Network) standard may be connected to the control devices G11 and G12.

  The control devices G11 and G12 perform various controls such as exchange processing or protocol conversion between opposing devices (such as the gateway 200 and the control device of the communication partner) in order to realize end-to-end communication between communication terminals. Bear. The control devices G11 and G12 specify signals (digital signals such as audio data, video and image data, data for performing various services, etc.) communicated via the base station via the communication network 100. Process according to the communication type.

  FIG. 2 is a functional block diagram showing the control device G11 of FIG. The control device G12 has the same configuration. The control device G11 includes a packet switch unit 41, a base station interface unit 42, a network interface unit 43, a memory 44, and a main control unit 45. Among these, the base station interface unit 42 performs an interface process for accommodating the base station CS11 (and a subordinate base station not shown) via an individual line. The network interface unit 43 performs interface processing with the communication network 100.

  Each of the base station interface unit 42 and the network interface unit 43 has a function of exchanging IP packets, and these IP packets are exchanged via the packet switch unit 41. Various operations inside the apparatus including packet switching are comprehensively controlled by the main control unit 45, and programs and various setting data for the operations are stored in the memory 44.

  FIG. 3 is a diagram illustrating an example of a database stored in the memory 44. That is, the memory 44 stores the adjacent base station information 44a in the storage area. The adjacent base station information 44a is basically a database in which, for each permutation in which three base stations under the control of each control device are arranged, the probability that the permutation has occurred in the history of handover that has occurred in the mobile communication system. is there. This database is constructed while being updated as the history of handover is accumulated over time.

  For example, when 5 base stations of A station, B station, C station, D station, and E station are connected to the control device, it consists of a plurality of base stations such as two, three, four or five. Permutations can be considered. In the adjacent base station information 44a according to this embodiment, a permutation composed of three of these base stations is considered. The reason for this is that in the handover prediction, “the base station that is currently communicating”, “the base station that was connected immediately before the base station that is currently communicating”, and “the base station that is currently communicating” This is because it is reasonable to consider the three "probable base stations". Of course, a permutation of four or more base stations can also be considered. In this way, although the database is enlarged, the possibility of more accurate handover prediction is increased.

  A permutation of base stations caused by a handover indicates that base stations included in the permutation are adjacent to each other. The probability indicated in the adjacent base station information 44a indicates the possibility of being selected as a handover destination in the future when handover is performed from the base station before the handover to the base station currently communicating, and is sorted in descending order of numerical value for each base station. Is done. In FIG. 3, the base station information before the handover is a history from the base station that was communicating immediately before the base station that is currently communicating, but a plurality of previous information may be included.

  FIG. 4 is a block diagram showing functions provided in the main control unit 45 of FIG. The main control unit 45 includes a database construction unit 45a, a handover prediction unit 45b, a handover control unit 45c, a data integration unit 45d, and a link formation unit 45e. These are processing functions realized by arithmetic processing of a CPU (Central Processing Unit) based on instructions described in a program stored in the memory 44.

  The main control unit 45 obtains and processes data such as the time of handover and the identifiers of base stations before and after the handover, in addition to data related to events such as call, connection, movement, and end of call of the mobile terminal. These data are accumulated as a history as time passes. This history is stored in the control devices G11 and G12 or the server device 400.

  In FIG. 4, the database construction unit 45a constructs the adjacent base station information 44a of FIG. 3 based on the handover history data. For example, if there are a plurality of base stations CS11, CS12, CS13, and CS14 in the adjacent base station information 44a, a permutation (CS11, CS12, CS13) obtained by extracting three base stations. ), (CS11, CS12, CS14), (CS11, CS13, CS12), (CS11, CS13, CS14), (CS11, CS14, CS12), (CS11, CS14, CS13), (CS12, CS11, CS13), (CS12, CS11, CS14), (CS12, CS13, CS11), (CS12, CS13, CS14), (CS12, CS14, CS11), (CS12, CS14, CS13), (CS13, CS11, CS12), (CS13) , CS11, CS14), (CS13, CS12, C 11), (CS13, CS12, CS14), (CS13, CS14, CS11), (CS13, CS14, CS12), (CS14, CS11, CS12), (CS14, CS11, CS13), (CS14, CS12, CS11) , (CS14, CS12, CS13), (CS14, CS13, CS11), (CS14, CS13, CS12). For example, in the permutation (CS12, CS11, CS14), the first is the base station CS12, the second is CS11, and the third is CS14.

As the time elapses after the mobile terminal PS has repeatedly handed over to the base station, for example, (CS11, CS14, CS12) → (CS14, CS12, CS13), a permutation in which the connection destination base stations are sequentially arranged To occur. The adjacent base station information 44a associates the generated probability for each permutation. The probability means frequency in a broad sense, and the occurrence frequency, occurrence frequency, or occurrence frequency may be associated with each permutation in the adjacent base station information 44a.
There are also permutations that cannot occur depending on the arrangement of base stations. For example, it is conceivable that base stations that are located apart from each other are not included in the same permutation no matter how much time elapses. For such a permutation, it is not necessary to provide a data storage area in the memory 44.

  By using the adjacent base station information 44a, it is possible to predict a base station that can be a partner for the next handover. For example, if the next handover destination of the mobile terminal handed over from CS11 to CS14 is the permutation having the highest probability among a plurality of permutations (CS11, CS14, CS12), (CS11, CS14, CS13), the third destination It can be selected as a base station. The database construction unit 45a constructs adjacent base station information 44a that can be used for such purposes.

  The handover predicting unit 45b predicts the next handover destination base station of the mobile terminal PS in communication based on the adjacent base station information 44a. The handover control unit 45c instructs the mobile terminal PS in communication to perform handover to the predicted base station. That is, in this embodiment, the handover of the mobile terminal PS is realized under the initiative of the control device G11.

The data integration unit 45d performs processing for integrating adjacent base station information 44a between the control devices G11 and G12 and synchronizing data. That is, depending on the movement route of the mobile terminal PS, a handover across control devices may occur. For example, in FIG. 1, it is assumed that the PS 11 under the base station CS11 switches the connection destination to the base station CS21 by handover. Such a handover is referred to as an inter-device handover. Then, the data integration unit 45d joins the base station under the control of the other control device to the adjacent base station information 44a, and registers the occurrence probability in association with the permutation including the base station. As a result, adjacent base station information 44a across the control devices is constructed.
Specifically, the data integration unit 45d exchanges data including the identification information of the base station related to the inter-device handover and the time information at the time when the inter-device handover occurs with other control devices. Based on the data, adjacent base station information 44a is integrated.

  The link forming unit 45e forms, prior to the handover, a link for continuing communication between the mobile terminal in communication and its counterpart on the individual line of the base station predicted as the connection destination of the handover. In particular, when the occurrence of inter-device handover is predicted, the link forming unit 45e forms a communication link between the control device under its control of the counterpart base station and its own device, Secure a communication channel with the other party in advance. Next, the operation of the above configuration will be described.

  FIG. 5 is a diagram showing an example of the positional relationship between base stations, and the dotted line in the figure shows an example of a rough zone boundary of each control device G11, G12. In FIG. 5, the control device G11 has base stations CS11 to CS15 under its control, and the control device G12 accommodates base stations CS21 to CS23 under its control. Of these, paying attention to CS11, CS21, and CS22, these are adjacent to each other, and depending on the route of the mobile terminal PS, handover in this order (or reverse order) may occur.

  FIG. 6 is a diagram showing details of FIG. Base stations CS11, CS21 and CS22 form radio zones A11, A12 and A13, respectively. In the following, it is assumed that the mobile terminal PS first resides in the radio zone A11, and then moves to enter the radio zone of the base station CS21 under the control of the control device G12.

  When the mobile terminal PS approaches the boundary between the radio zones A11 and A12, a handover from the base station CS11 to CS21 is performed. At that time, the control device G11 regards the control device G12 as an adjacent control device. Then, the control device G11 transmits the adjacent base station information 44a-1 managed by itself to the control device G12, and the control device G12 similarly transmits the adjacent base station information 44a-2 in the own device to the control device G11. . The control device G11 that has received the adjacent base station information 44a-2 integrates and holds the received adjacent base station information 44a-2 in the adjacent base station information 44a-1 that it manages. The same applies to the control device G12.

  FIG. 7 is a sequence diagram showing a procedure performed between control apparatuses when neighboring base station information is shared. Initially, the mobile terminal PS11 is in communication with the base station CS11 (step S101), and between the base station CS11 and the control device G11, between the control device G11 and the opposite device (terminal of the other party of the mobile terminal PS11). Are in a call connection state (steps S102 and S103). That is, a communication link is formed between the mobile terminal PS11 and the opposite device via the base station CS11 and the control device G11.

  Thereafter, when the mobile terminal PS11 moves and hands over to the base station CS21, a connection request is sent from the mobile terminal PS11 to the base station CS21 (step S104), the base station CS21 returns a connection response (step S105), and the mobile terminal PS11. And the base station CS21 are in a communication state (step S106).

  Next, the base station CS21 transmits a handover request to the control device G12 (step S107), thereby performing a handover process across the control devices G11 and G12 (step S108). When the handover process ends normally, the control device G12 returns a handover response to the base station CS21 (step S109), and the call connection state is established between the base station CS21 and the control device G12 and between the control device G12 and the opposite device. (Steps S110 and S111).

  After the procedure so far is completed, each control device G11, G12 considers each other as an adjacent partner (adjacent control device) triggered by a handover between each other. Then, the control devices G11 and G12 exchange adjacent base station information 44a-1 and 44a-2 stored with each other, and perform base station information sharing processing (step S112). The data exchanged between the control devices G11 and G12 includes, for example, identification information (IP address, MAC address, etc.) of the base stations CS11 and CS21, time data at the time when the inter-device handover is performed, and the like. As a result, the adjacent base station information 44a is integrated between the control devices G11 and G12.

  As shown in FIG. 8, it is assumed that the control device G11 stores adjacent base station information having only the base station CS1n (n is 1 to 6) under its control as an element. When an inter-device handover occurs from this state, for example, a handover from the base station CS11 to the base station CS21, the data is integrated as shown in FIG. 9, and the data shown in the hatched cell portion of FIG. 9 is generated. That is, data about the base station CS21 under the control device G21 is added to the adjacent base station information stored in the control device G11. In this way, adjacent base station information is constructed in a manner that also includes information on base stations under the control of other control devices.

  FIG. 10 is a sequence diagram illustrating an example of a processing procedure in inter-device handover prediction using integrated adjacent base station information. In this procedure, each control device G11, G21 predicts not only a base station under its control but also a base station managed by another adjacent control device as a handover destination of a mobile terminal. That is, the handover predicting unit 45b uses the integrated adjacent base station information to predict the base station with the highest transition probability including the base stations under other devices as the handover destination base station.

  In FIG. 10, first, the mobile terminal PS11 is in communication with the base station CS11 (step S201), and the call connection state is established between the base station CS11 and the control device G11 and between the control device G11 and the opposite device. (Step S202, Step S203). When the control device G11 determines the base station CS21 under the control device G12 as the handover destination of the mobile terminal PS11, the control device G11 transmits a prediction destination base station connection instruction to the control device G12 to connect to the base station CS21 (step S204). ). This prediction destination base station connection instruction includes information on the opposite device (IP address, etc.).

  In response, a communication link is formed between the control device G12 and the base station CS21, and both are connected (step S205). Then, the control devices G11 and G12 shift to a handover waiting state so that the communication path can be switched immediately (step S206). Thereafter, when the base station CS21 already connected to the control device G12 receives a connection request from the mobile terminal PS11 (step S207), the base station CS21 returns a connection response to the mobile terminal PS11 (step S208).

  In response to this, the mobile terminal PS11 and the base station CS21 enter a communication state (step S209), and then a path switching instruction is transmitted from the base station CS21 to the control device G12 in the handover waiting state (step S210). The control device G12 performs a route switching process to the control device G11 in response to the route switching instruction (step S211), and executes a connection establishment process to the opposite device using the information of the prediction destination base station connection instruction (step S204). (Step S212). Thereby, the call connection between the control device G12 and the opposite device is established (step S213).

  As described above, in this embodiment, when an inter-device handover occurs between base stations under control of different control devices due to movement of a mobile terminal, adjacent base station information 44a is mutually exchanged between related base stations. Communicate neighboring base station information stored in each other. Each of the control devices G11 and G21 performs handover prediction using the integrated adjacent base station information. As a result, cooperation between the control devices can be achieved, and high-speed handover can be realized for movement across the control devices.

  Even in the existing technology, the neighboring base station information is used to predict the handover destination base station. However, the neighboring base station information is limited to the base station that is locally managed by the control device itself. Could not realize the handover prediction and could not promote the high-speed movement of the mobile terminal.

On the other hand, in this embodiment, adjacent base station information is integrated between control apparatuses, and the processing procedure is listed as follows, for example.
When the inter-device handover occurs, it is determined whether or not the related control devices are adjacent to each other, and if they are considered to be adjacent, a sharing sequence of adjacent base station information is performed. That is, if a handover involving another device occurs, the other device is regarded as an adjacent partner.
The control device transmits adjacent base station information held by the own device to the control device considered to be adjacent, and acquires adjacent base station information sent from the counterpart control device. Then, the adjacent base station information acquired from each other is integrated (merged) with the adjacent base station information stored in the next apparatus.
-The control device refers to the base station with the highest transition probability by referring to the adjacent base station information from the past handover history of the base station through which the mobile terminal has moved and the base station currently located. To predict. In particular, for a mobile terminal accommodated in a base station located at the boundary of the area range of the control device, a handover destination is predicted based on the integrated adjacent base station information.
When the inter-device handover is predicted, the control device instructs the adjacent control device to the handover destination base station and completes the connection of the individual line, and itself forms a communication link with the adjacent control device.

  In this way, in a mobile communication system based on autonomous distributed installation of base stations, the neighboring base station information obtained by the control device based on the terminal handover history is autonomously shared between neighboring control devices. It becomes possible to do. The control device, which is a device on the network side, performs handover prediction based on shared neighboring base station information, and detects the necessity of handover processing from the base station to the base station. A handover instruction is transmitted in advance. Further, when a handover across control devices is predicted, the next control base station is instructed to the adjacent control device, and a handover process is performed in advance between the adjacent control device and the next base station. In this way, adjacent base station information is shared between adjacent control devices, and the predicted base station and control device are connected prior to the radio section, thereby realizing high-speed handover across the control devices. Is possible. Accordingly, it is possible to provide a mobile communication system, a control device thereof, and a database creation method capable of smoothly performing a handover moving between control devices, and thereby improving high-speed movement performance at low cost. Is possible.

  In this embodiment, adjacent base station information is not constructed for all base stations, but a database is constructed only for adjacent base stations. The same applies to the control device, and even when there are three or more control devices, a step of determining whether or not the control devices are adjacent to each other is performed. This is because the database is updated as the handover history is accumulated, so that unnecessary enlargement of the database can be prevented and system resources can be saved.

The present invention is not limited to the above embodiment. For example, the functions of the control devices G11 and G21 can be given to the gateway 200 or the server device 400.
In addition, it is possible to construct adjacent base station information separately for each control device in a local database that targets only base stations under its control and a shared database that targets base stations that are not under its control. That is, the database construction unit 45a in FIG. 4 constructs a local database for handover between base stations under its control, and if the inter-device handover occurs, the data integration unit 45d integrates the shared database as a posting. May be performed. The inter-device handover can be predicted by referring to the shared database, and it is possible to further increase the moving speed of the mobile terminal.

  Further, in this embodiment, adjacent base station information between the control apparatuses is integrated when a handover occurs, but the database may be integrated from the server apparatus 400 by an operator's manual operation, for example. In particular, it is conceivable to perform such work when a new base station is added. Of course, the control device may detect the addition of a base station and autonomously share adjacent base station information.

  In addition, base stations that frequently generate inter-device handovers may be selected in advance, and if a handover to the base station is predicted, a communication link may be formed between the control devices at that time. . In this way, inter-device handover can be performed more smoothly.

  Furthermore, the present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment.

  DESCRIPTION OF SYMBOLS 100 ... Communication network, 200 ... Gateway, 300 ... Internet, 400 ... Server apparatus, G11, G12 ... Control apparatus, CS11, CS12 ... Base station, PS11, PS12 ... Mobile terminal, PC ... Personal computer, TEL ... Fixed telephone, 41 ... Packet switch part, 42 ... Base station interface part, 43 ... Network interface part, 44 ... Memory, 44a ... Neighboring base station information, 45 ... Main control part, 45a ... Database construction part, 45b ... Handover prediction part, 45c ... Handover Control unit, 45d ... data integration unit, 45e ... link formation unit

Claims (11)

A plurality of base stations that each form a radio zone and wirelessly accommodate mobile terminals that perform handover between the radio zones; and a plurality of control devices that distribute and accommodate the plurality of base stations under their own control via individual lines; A mobile communication system comprising:
The plurality of control devices include:
For each permutation in which a plurality of base stations under its control are arranged, a construction means for constructing a database in association with the frequency of occurrence of the permutation in the history of handover that has occurred in the mobile communication system, with the accumulation of the history,
Predicting means for predicting the next handover destination base station of the mobile terminal in communication based on the frequency;
Instructing means for instructing the communicating mobile terminal to perform handover to the predicted base station;
When an inter-device handover occurs in which the mobile terminal transitions between a base station under its own control and a base station under the control of another control device, a permutation including the base stations under the control of the other control device and its frequency are stored in the database. A mobile communication system comprising: an integrated processing means for joining the database and integrating the database with the other control device. The integration processing means exchanges data including the identification information of the base station related to the inter-device handover and the time of the inter-device handover with the other control device, and based on this data, the database The mobile communication system according to claim 1, wherein the mobile communication system is integrated. The control device further includes:
A link forming unit is provided for forming a link for continuing communication between the mobile terminal in communication and its counterpart in an individual line of the predicted base station prior to handover. Item 4. The mobile communication system according to Item 1. When the prediction unit predicts the occurrence of the inter-device handover, the link forming unit communicates between the control device under the control of the predicted base station and the own device prior to the inter-device handover. The mobile communication system according to claim 3, wherein a link is formed. The database includes a local database that targets only base stations under its control, and a shared database that targets base stations that are not under its control,
The construction means constructs the local database,
The mobile communication system according to claim 1, wherein the integration processing unit integrates the shared database with another control device. A control apparatus that accommodates a base station that accommodates a mobile terminal that moves by handover between radio zones of a mobile communication system within the radio zone under its own control via an individual line,
For each permutation in which a plurality of base stations under its control are arranged, a construction means for constructing a database in association with the frequency of occurrence of the permutation in the history of handover that has occurred in the mobile communication system, with the accumulation of the history,
Predicting means for predicting the next handover destination base station of the mobile terminal in communication based on the frequency;
Instructing means for instructing the communicating mobile terminal to perform handover to the predicted base station;
When an inter-device handover occurs in which the mobile terminal transitions between a base station under its own control and a base station under the control of another control device, a permutation including the base stations under the control of the other control device and its frequency are stored in the database. And an integrated processing means for integrating the database with the other control device. The integration processing means exchanges data including the identification information of the base station related to the inter-device handover and the time of the inter-device handover with the other control device, and based on this data, the database The control device according to claim 6, wherein the control device is integrated. And further comprising link forming means for forming a link for continuing communication between the communicating mobile terminal and its counterpart on the individual line of the predicted base station prior to handover. The control device according to claim 6. When the prediction unit predicts the occurrence of the inter-device handover, the link forming unit communicates between the control device under the control of the predicted base station and the own device prior to the inter-device handover. The control device according to claim 8, wherein a link is formed. The database includes a local database that targets only base stations under its control, and a shared database that targets base stations that are not under its control,
The construction means constructs the local database,
The control apparatus according to claim 6, wherein the integration processing unit integrates the shared database with another control apparatus. A database creation method implemented in a control device that accommodates a base station that accommodates a mobile terminal that moves by handover between radio zones of a mobile communication system in its own radio zone,
For each permutation in which a plurality of base stations under its control are arranged, the control device constructs a database that associates the frequency of occurrence of the permutation in the history of handovers that occurred in the mobile communication system as the history is accumulated. And
When an inter-device handover occurs in which the mobile terminal makes a transition between a base station under its control and a base station under the control of another mobile device, a permutation including base stations under the control of the other control device and A database creation method comprising: joining a frequency to the database and integrating the database with the other control device.

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