JP4982541B2 - Mobile communication system and control device therefor - Google Patents

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 technology 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, a base station is often installed without careful planning (also referred to as station design) such as its installation position and positional relationship with adjacent base stations. Interference between the resulting areas is avoided by each base station autonomously dealing with it.

  In this type of system, the mobile terminal takes the initiative in handover (H / O), and the base station is switched by a re-call request from the mobile terminal. That is, the mobile terminal measures the received radio wave intensity from the connected base station, the error rate, or the like, and requests handover to the base station with the highest radio wave intensity or the base station with the lowest error rate.

  However, the number of mobile terminals that can be acquired by the base station is limited. That is, the base station cannot accept the handover of the mobile terminal in a state where resources such as the number of channels in the wireless section and the number of channels in the wired section connecting the base station and the network remain (resource busy). A mobile terminal rejected for handover attempts to hand over to another base station, but if this is repeated, the handover may not be executed and communication may be disconnected. In particular, when the mobile terminal moves at high speed, the processing is not in time, and there is a high possibility of being disconnected.

  Japanese Patent Application Laid-Open No. 2004-151867 discloses a technique for solving this type of problem. However, in the technique of this document, since control for canceling resource busy is started from the time when a handover request is generated, there is still a possibility that processing may not be in time.

International Publication Number WO2005 / 025253

In order to achieve the above object, according to one aspect of the present invention, there are provided a plurality of base stations each accommodating an arbitrary number of mobile terminals by radio, and a control device for concentrating these base stations and connecting them to a communication network. In the mobile communication system provided, the base station includes notification means for notifying the control device of information relating to a remaining amount of resources that wirelessly accommodates the mobile terminal and connects to the communication network, Receiving means for receiving information relating to the remaining amount of the resource notified from the notification source base station , and specifying the remaining amount of the resource of the notifying source base station based on the information relating to the remaining amount of the resource compared to the value, when the Tsu Do below the specified value, for at least one mobile terminal in connection to the notification source base station is instructed to perform a handover to another base station finger Mobile communication system, characterized in that it comprises a means.

  In order to achieve the above object, according to one aspect of the present invention, a mobile communication system comprising a plurality of base stations that wirelessly accommodate mobile terminals and a control device that collects these base stations and connects them to a communication network. The base station comprises notification means for notifying the control device of information relating to a remaining amount of resources that wirelessly accommodates the mobile terminal and connects to the communication network, the control device notifying from the notification source If the resource remaining amount of the notification source base station is equal to or less than a specified value based on the information related to the resource remaining amount, at least one of the mobile terminals connected to the notification source base station On the other hand, there is provided a mobile communication system characterized by comprising instruction means for instructing handover to another base station.

  By taking such means, the remaining amount of the resource is notified from the base station to the control device. As a result, the control device can detect the base station where the resource is busy. When the base station that has become resource busy is detected, the control apparatus gives an instruction to hand over the mobile terminal connected to the base station to another base station. When the mobile terminal that has received this instruction hands over to another base station, the remaining resources are leveled between the base stations. This is performed as soon as resource busy occurs, regardless of whether a new call request from the terminal is generated.

  As a result, communication disconnection due to resource shortage during handover can be resolved. In addition, it is possible to perform resource leveling after grasping the number of remaining resources of adjacent base stations. Alternatively, only base stations that are likely to be resource busy can be monitored. Furthermore, since base stations where resource busy occurs frequently can be limited, it can be used as a guideline for installing new base stations.

  According to the present invention, it is possible to provide a mobile communication system, a control apparatus, and a base station apparatus capable of eliminating the resource busy of the handover destination in advance, thereby improving the high-speed movement performance of the mobile terminal.

1 is a system diagram showing an embodiment of a mobile communication system according to the present invention. The figure which shows the condition where resource busy occurred. The figure which shows the basic effect | action in embodiment of this invention. The functional block diagram which shows the processing function of mobile terminal PS, base station CS, and the control apparatus 4 concerning 1st Embodiment of this invention. The sequence diagram which shows the process sequence implemented among mobile terminal PS, base station CS, and the control apparatus 4 concerning 1st Embodiment of this invention. The figure which shows the effect | action in the sequence of FIG. The sequence diagram which shows the process sequence implemented among mobile terminal PS, base station CS, and the control apparatus 4 in the modification of 1st Embodiment. The figure which shows the effect | action in the sequence of FIG. The functional block diagram which shows the processing function of mobile terminal PS, base station CS, and the control apparatus 4 concerning 2nd Embodiment of this invention. The figure which shows an example of the resource management table 44 of FIG. The sequence diagram which shows the process sequence implemented among mobile terminal PS, base station CS, and the control apparatus 4 concerning 2nd Embodiment of this invention. The sequence diagram which shows the process sequence implemented among mobile terminal PS, base station CS, and the control apparatus 4 in the modification of 2nd Embodiment. The functional block diagram which shows the processing function of mobile terminal PS, base station CS, and the control apparatus 4 concerning 3rd Embodiment of this invention. The functional block diagram which shows the processing function of mobile terminal PS, base station CS, and the control apparatus 4 concerning 4th Embodiment of this invention. The functional block diagram which shows the processing function of mobile terminal PS, base station CS, and the control apparatus 4 concerning 5th Embodiment of this invention.

FIG. 1 is a system diagram showing an embodiment of a mobile communication system according to the present invention. The mobile communication system S of FIG. 1 is formed with a plurality of base stations CS (CS1 to CSn) and a control device 4 that accommodates these base stations CS1 to CSn via individual lines as the core. The individual line is an ISDN (Integrated Service Digital Network) line or an IP (Internet Protocol ) line . Alternatively, there can be a wireless line . Other fixed telephone 2 may be connected to the control device 4 of this.

The base stations CS1 to CSn each form a radio zone, and the mobile terminal PS (PS1, PS2) is accommodated via a radio channel in the base station forming the radio zone in any one of the radio zones. The mobile communication terminal PS performs sequentially switching handover base stations connected ahead with the move between the radio zones. Of course, the number of mobile terminals is not limited to two.

  The control device 4 is connected to the communication network via the gateway 1. The communication network is an exchange network such as ISDN 40 or an IP network 6 via an Internet service provider (ISP) 5. The IP network 6 is a packet communication network such as a wide area Ethernet (registered trademark) or an IP-VPN (IP-Virtual Private Network) connection service. The gateway 1 has a protocol conversion function for connecting these heterogeneous networks and the mobile communication system S.

FIG. 2 is a diagram illustrating a situation where resource busy occurs. 2, in the zone each of a plurality of base stations CS1~CS4 is deployed, or the mobile terminal PS1 in the vicinity of its consider the situation to be moved. The mobile terminal PS1 communicating with the base station CS4 is expected to be handed over to the base station CS3 by movement . However, at that time, when the resources of the base station CS3 are fully used and there is no room for accepting a new call, the existing technology is handed over to the base stations CS1 and CS2 other than the base station CS3. Therefore, a control sequence for that purpose is required, and the high-speed movement performance is adversely affected. If the handover to the base stations CS1 and CS2 is successful, there is no problem, but if the resources of these base stations are also busy, communication must be disconnected. Hereinafter, a technique capable of solving such a problem will be described.

  FIG. 3 is a diagram showing a basic operation in the embodiment of the present invention. In this embodiment, the resource of the base station (CS3 in this case) that caused resource busy is moved to another base station. That is, as shown in FIG. 3, resource busy is eliminated by handing over the mobile terminal PS2 connected to the base station CS3 to another base station (for example, CS2). The timing may be at the time of a handover request from the mobile terminal PS or at the time of a new call, for example. In this way, the remaining resources of a plurality of base stations are leveled, so that the success rate of handover can be increased even under conditions where the mobile terminal PS moves at high speed.

[First Embodiment]
FIG. 4 is a functional block diagram showing processing functions of the mobile terminal PS, the base station CS, and the control device 4 according to the first embodiment of the present invention. In FIG. 4, the mobile terminal PS includes a call connection processing unit P1, a base station selection unit P2, and a handover control unit P3. The base station CS includes a call connection processing unit C1, a handover control unit C2, a remaining resource management unit C3, a remaining resource notification unit C4, and a handover instruction receiving unit C5. The control device 4 includes a call connection processing unit 41, a remaining resource reception unit 42, and a handover instruction unit 43.

  Among these, the call connection processing units P1, C1, and 41 set a call between the mobile terminal PS and its counterpart by a known call connection processing sequence. The base station selection unit P2 of the mobile terminal PS selects an optimal base station for handover based on, for example, the received radio wave intensity from the connected base station. Note that the base station selection criterion is not limited to the radio wave intensity, and an error rate may be used, or if there are a plurality of base stations capable of receiving radio waves, any one of them may be selected. .

The handover control unit P3 of the mobile terminal PS performs handover to the selected base station in cooperation with the handover control unit C2 of the base station CS. Further, the handover control unit P3 executes the handover in a form corresponding to the handover instruction message given from the base station. That is, the control device 4 includes a handover instruction unit 43 and gives a handover instruction message to the base station CS . This message is notified to the destination mobile terminal PS via the handover instruction transmission / reception unit C5 of the base station CS. In response to this, the mobile terminal PS executes a handover to the base station CS specified by the message.

Incidentally base station CS, the remaining resource management unit C3, Ru with the remaining resource notification unit C4. Remaining resource management unit C3 of this manages the remaining resource amount for accommodating the mobile terminal PS in real time. When the remaining resource becomes 0, the remaining resource notification unit C4 notifies the control device 4 to that effect. In response to this, when the remaining resource receiving unit 42 receives a notification from the base station CS that the remaining resource has become 0, the control device 4 detects the occurrence of resource busy and connects to the notifying source base station CS . The mobile terminal PS in the middle is instructed to perform handover to another base station CS . Even if the number of remaining resources is 1 or more, if it falls below the specified value, the control device 4 is notified of this.

  FIG. 5 is a sequence diagram illustrating a processing procedure performed between the mobile terminal PS, the base station CS, and the control device 4 in the above configuration. In FIG. 5, it is assumed that mobile terminals PS1, PS2, PS3, PS4, base stations CS1, CS2, CS3, CS4, and the control device 4 are related. Assume that the remaining resources of the base stations CS1, CS2, CS3, and CS4 in the initial state are 10, 10, 3, and 10, respectively.

From this state, when the three mobile terminals PS1, PS2, and PS3 each send a call connection request (201) to the base station CS3, the base station CS3 returns a call connection response (202) to each of the mobile terminals PS1, PS2, and PS3. To do. Thus, the communication link with a base station CS3 to each mobile terminal are sequentially formed, the remaining resources of the base station CS3 is gradually reduced with the formation of the link. In this example, the remaining resource becomes 0 when a link with the third mobile terminal PS3 is formed.

When the remaining resource becomes 0 , the base station CS3 notifies the control device 4 that the remaining resource has become 0 by the remaining resource number notification (203) . Receiving this notification , the control device 4 transmits a handover instruction message (204) to the notification source base station CS3. The base station CS3 transmits a handover request (205) to one of the mobile terminals PS1, PS2 and PS3 (PS1 in this case) in communication. Decide on the base station by yourself. Here, it is assumed that the base station CS2 having the highest reception level among the plurality of base stations receiving radio waves is determined as the handover destination. Then, a call connection request (201) and a call connection response (202) are exchanged between the mobile terminal PS1 and the base station CS2, and the handover of the mobile terminal PS1 to the base station CS2 is completed.

  Furthermore, when the mobile terminal PS4 connects to the base station CS3 (call connection request (201), call connection response (202)), the remaining resources of the base station CS3 become 0 again. Thereafter, the same procedure is followed, and the mobile terminal PS4 reconnects to the base station CS4, for example. In this way, if a base station having a remaining resource of 0 occurs, the resource is immediately moved, and resource busy is eliminated.

  In the sequence of FIG. 5, the base station CS3 whose remaining resource has become zero notifies the control apparatus 4 (203), and returns a handover instruction message (204) to the base station CS3 to take the initiative of the control apparatus 4. To request handover. Instead, the base station CS3 whose resource has become 0 may autonomously send a handover request (205) to the mobile terminal PS1 to secure the resource.

  FIG. 6 is a diagram showing an operation in the sequence of FIG. When the mobile terminals PS1, PS2, PS3 connect to the base station CS3, the remaining resources of the base station CS3 become 0. When this is detected, for example, the mobile terminal PS1 hands over to the base station CS2. When the mobile terminal PS4 connects to the base station CS3 again and the remaining resources become 0, control for handing over the mobile terminal PS4 to the base station CS4, for example, is performed.

  As described above, in this embodiment, the base station CS that has detected that the remaining resource is equal to or less than a specified value (for example, 0) notifies the control device 4 of this fact. Receiving this, the control device 4 returns a handover instruction message to the notifying base station. The base station that has received this instructs the connected mobile terminal PS to perform handover to another station. Receiving this, the mobile terminal PS performs a handover, for example, toward the one having the highest reception level among other base stations receiving radio waves.

  Since this is done, if a base station whose remaining resources are 0 occurs, the resources of the base station are immediately released, and the resource usage does not deviate among the base stations. In other words, the amount of resource usage between base stations is leveled, and resource busy can be prevented and the success probability of handover can be increased. As a result, it becomes possible to improve the high-speed movement performance of the mobile terminal.

  In this embodiment, the number of mobile terminals PS instructing handover from the base station that has received the handover request message is not limited to one, and may be arbitrarily determined in the base station. For example, if a plurality of handover requests are transmitted from the base station CS, a plurality of mobile terminals PS are reconnected to other stations, and the number of resources used can be greatly reduced by a single process. Further, the criterion for selecting a base station to be handed over by the mobile terminal is not limited to the radio wave reception intensity, but may be based on a low error rate. This selection criterion can be determined according to the system design.

[Modification of First Embodiment]
Next, a modification of the first embodiment will be described.
FIG. 7 is a sequence diagram illustrating a processing procedure performed between the mobile terminal PS, the base station CS, and the control device 4 according to the modification of the first embodiment. In FIG. 7, it is assumed that the mobile terminals PS1, PS2, PS3, PS4, PS5, PS6, base stations CS1, CS2, CS3, CS4, and the control device 4 are related. Assume that the remaining resources of the base stations CS1, CS2, CS3, and CS4 are 10, 10, 3, and 3, respectively, in the initial state.

  It is assumed that the mobile terminals PS1, PS2, and PS3 are sequentially connected to the base station CS3 by exchanging the call connection request (201) and the call connection response (202) from this state. Also assume that the mobile terminals PS5 and PS6 are connected to the base station CS4. This state is shown in FIG. Since the number of remaining resources is 0 for the base station CS3, the base station CS3 notifies the control device 4 of the remaining resource number notification (203).

  In response to this, the control device 4 transmits a handover instruction message (204) to the base stations CS1, CS2 and CS4 other than the notification source base station CS3. Receiving the handover instruction message, the base stations CS1, CS2, and CS4 confirm their own remaining resources and determine that the resources are free or NG. In FIG. 7, the base station CS4 has no available resources, but the base stations CS1 and CS2 have available resources.

  Therefore, the base stations CS1 and CS2 transmit handover instructions to the subordinate mobile terminals PS at the same time triggered by the handover instruction message (204) from the control device 4. This handover instruction instructs the subordinate mobile terminal PS to perform handover to the base stations CS1 and CS2 itself.

That is, the base stations CS1 and CS2 send a handover instruction message to a mobile terminal PS that is not connected to itself but is located in the radio zone (referred to as a mobile terminal under its control ) so as to perform a handover to itself. Send. The mobile terminal PS that has received this message determines the handover destination base station based on, for example, the radio wave intensity and the error rate.

In FIG. 7, for example, if the mobile terminal PS1 decides a handover to the base station CS2, the mobile terminal PS1 sends and receives a call disconnection request (205) and a call disconnection response (206) to and from the connected base station CS3. Then, the connection with the base station CS3 is canceled, and a call connection request (201) and a call connection response (202) are immediately exchanged with the base station CS2 to be handed over to the base station CS2.

  In the first embodiment, a handover instruction message is given to a resource busy base station so that the connected mobile terminal is handed over to another station. On the other hand, in this modified example, a handover instruction message is given to a base station having sufficient resources, and a mobile terminal connected to a base station having no resources is called into the own station to be handed over. Even in this way, the remaining resources are leveled between the base stations, and it is possible to increase the success probability of handover and improve the high-speed movement performance.

[Second Embodiment]
FIG. 9 is a functional block diagram showing processing functions of the mobile terminal PS, the base station CS, and the control device 4 according to the second embodiment of the present invention. In FIG. 9, parts common to FIG. 4 are given the same reference numerals, and only different parts will be described here.
In FIG. 9, the control device 4 includes a resource management table 44. The resource management table 44 is a table for managing the number of remaining resources in association with each base station as shown in FIG. That is, in this embodiment, the remaining resource notification unit C4 of each base station CS notifies the control device 4 of the number of its remaining resources, for example, periodically or in response to an inquiry from the control device 4. That is, regardless of whether or not the number of remaining resources is equal to or less than a specified value, the number of remaining resources at that time is notified to the control device 4. The remaining resource receiving unit 42 of the control device 4 records the received number of remaining resources for each base station in the resource management table 44. The resource management table 44 is updated every time the number of remaining resources is notified from each base station CS. Note that message information that can grasp the resource status of each base station at that time is not limited to the number of remaining resources. An example of this type of message is a TRAP message used in SNMP (Simple Network Management Protocol).

FIG. 11 is a sequence diagram showing a processing procedure performed between the mobile terminal PS, the base station CS, and the control device 4 according to the second embodiment of the present invention. In FIG. 11, the same steps as those in FIG. 5 are denoted by the same reference numerals, and only different portions will be described here.
The difference from the sequence in FIG. 5 is that not only when the number of remaining resources becomes zero, but also when the number of remaining resources changes, the base station CS3 notifies the number of remaining resources to the control device 4. In the point. Receiving this notification, the remaining resource receiving unit 42 of the control device 4 records the received number of remaining resources for each base station in the resource management table 44, and when the number of remaining resources becomes 0 or less than a specified value. A handover instruction message (204) is transmitted to the base station CS3. Thereafter, a processing sequence similar to that in FIG. 5 is performed, and a handover process is realized by giving a handover instruction message to the resource busy base station and evacuating the connected mobile terminal to another station.

  Furthermore, in this embodiment, the number of remaining resources of each base station is monitored in real time, and when resource busy occurs, this can be resolved immediately. Therefore, when a new call is generated from a mobile terminal, This does not require processing time for movement, and can respond immediately.

[Modification of Second Embodiment]
Next, a modification of the second embodiment will be described.
FIG. 12 is a sequence diagram illustrating a processing procedure performed among the mobile terminal PS, the base station CS, and the control device 4 in the modification of the second embodiment. In FIG. 12, the steps common to those in FIG. 7 are denoted by the same reference numerals, and only different portions will be described here.
The difference from the sequence in FIG. 7 is that not only when the number of remaining resources becomes zero but also when the number of remaining resources changes, the base station CS3 notifies the control device 4 of the number of remaining resources. In the point. Receiving this notification, the remaining resource receiving unit 42 of the control device 4 records the received number of remaining resources for each base station in the resource management table 44, and when the number of remaining resources becomes 0 or less than a specified value. A handover instruction message (204) is transmitted to the base station CS3. Thereafter, the same processing sequence as in FIG. 7 is performed, a handover instruction message is given to a base station with sufficient resources, and a mobile terminal connected to a base station with insufficient resources is called into the own station. Is realized. Even in this way, the remaining resources are leveled between the base stations, and it is possible to increase the success probability of handover and improve the high-speed movement performance.

[Third Embodiment]
FIG. 13 is a functional block diagram showing processing functions of the mobile terminal PS, the base station CS and the control device 4 according to the third embodiment of the present invention. In FIG. 13, parts common to FIGS. 4 and 9 are given the same reference numerals, and only different parts will be described here.
In FIG. 13, the mobile terminal PS includes a detection station information transmission unit P4. The detection station information transmitting unit P4 notifies the control device 4 of information for identifying the base station that has captured the radio wave via the connected base station. For example, the mobile terminal PS4 in FIG. 8 is connected to the base station CS3 but is in the radio zone of CS4 and receives radio waves from both base stations. In this embodiment, these base stations that can capture radio waves are referred to as detection stations, and the detection station information transmission unit P4 of the mobile terminal PS4 sends the identification information (such as base station ID) of the detection stations CS3 and CS4 to the base station CS3. Send. That is, the mobile terminal PS notifies the control device 4 of the identification information of the base station that develops each radio zone when the radio zones of the plurality of base stations overlap.

This identification information is received by the detection station information reception unit C6 of the base station CS, and is immediately notified to the control device 4 by the detection station information notification unit C7. Controller 4 Ru with terminal detection station management unit 45. The terminal detection station management unit 45 grasps, for each mobile terminal, a base station that is capturing radio waves based on the identification information of the detection station notified from each mobile terminal.

  In this embodiment, when sending a handover instruction message, the control device 4 refers to information managed by the terminal detection station management unit 45. That is, the terminal detection station management unit 45 manages the base stations that are receiving radio waves for each terminal, and the handover instruction unit 43 designates the base station (detection station) that is receiving these radio waves as a handover destination. To do. As a result, the target as a handover destination can be narrowed down to some extent, and the efficiency of handover control can be improved.

In FIG. 14, in addition to the configuration of FIG. 4, the control device 4 includes an adjacent base station information construction unit 46 and adjacent base station information 47. The neighboring base station information 47 is a database constructed by the neighboring base station information construction unit 46 based on, for example, the radio field intensity from the base station notified from each mobile terminal PS, and the distance relationship between the base stations CS and the neighboring It shows the relationship. By providing the control device 4 with the adjacent base station information 47, a plurality of candidate base stations can be specified as handover destinations of the mobile terminal PS in communication, and the optimum base station CS can be selected from among them. It becomes possible. This also makes it possible to further increase the handover success rate.

FIG. 15 is a functional block diagram showing processing functions of the mobile terminal PS, the base station CS and the control device 4 according to the fifth embodiment of the present invention. 14, parts that are the same as those in FIGS. 4, 9, 13, and 15 are given the same reference numerals, and only different parts will be described here.
15, in addition to the configuration of FIG. 14, the control device 4 includes a handover destination prediction unit 48. The handover destination prediction unit 48, the mobile terminal PS in moving the likely base station CS to be next handover, predicting with reference to neighbor base station information stored in the adjacent base station information storing section 47. The control device 4 compares the predicted state of the remaining resources of the base station CS with a threshold value, and if it is less than the threshold value , instructs the prediction destination base station to free up resources by the estimated handover execution time. To do. That is, the handover instruction unit 43 instructs the mobile terminal PS to perform a handover to the prediction destination base station.
In particular, the base stations that can be handed over are often limited as the speed of the mobile terminal increases, and in order to make a handover successful by combining handover destination prediction and resource release as in this embodiment. The effect is even greater.
As described above, according to each of the above embodiments, the resource busy at the handover destination can be eliminated in advance, and thereby the high-speed movement performance of the mobile terminal can be improved.

  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. Furthermore, constituent elements over different embodiments may be appropriately combined.

DESCRIPTION OF SYMBOLS S ... Mobile communication system, CS (CS1-CSn) ... Base station, PS (PS1-PS6) ... Mobile terminal, 40 ... ISDN, 1 ... Gateway, 2 ... Fixed telephone, 3 ... IP network, 4 ... Control device, 5 ... Internet service provider (ISP), 6 ... IP network, P1 ... call connection processing unit, P2 ... base station selection unit, P3 ... handover control unit, P4 ... detecting station information transmission unit, C1 ... call connection processing unit, C2 ... Handover control unit, C3 ... Remaining resource management unit, C4 ... Remaining resource notification unit, C5 ... Handover instruction transmission / reception unit , C6 ... Detection station information reception unit, C7 ... Detection station information notification unit, 41 ... Call connection processing unit, 42 ... Remaining resource reception unit, 43 ... handover instruction unit, 44 ... resource management table, 45 ... terminal detection station management unit, 46 ... adjacent base station information construction unit, 47 ... adjacent base station information Storage unit, 48 ... handover destination prediction unit

Claims (12)

A plurality of base stations each accommodating an arbitrary number of mobile terminals wirelessly and installed without a station design, and a controller for concentrating these base stations and connecting them to a communication network ,
In a mobile communication system that forms an area in a microcell system ,
The base station
Notification means for notifying the control device of information relating to the remaining amount of resources for wirelessly accommodating the mobile terminal and connecting to the communication network;
The controller is
Receiving means for receiving information on the remaining amount of the resource notified from the notification source base station;
Based on the information related to the remaining amount of the resource, the remaining amount of the resource of the base station of the notification source is compared with a specified value, and when it is equal to or less than the specified value, it is connected to the base station of the notification source Instruction means for instructing at least one of the mobile terminals to perform a handover to another base station;
A construction means for constructing a database indicating an adjacency relationship between the base stations based on radio field intensity from the plurality of base stations notified from each of the plurality of mobile terminals,
The mobile communication system, wherein the instruction unit specifies the other base station which is a handover destination using the database.   2. The mobile communication system according to claim 1, wherein the notification unit notifies the control device to that effect when the remaining amount of the resource becomes a predetermined value or less.   The mobile communication system according to claim 1, wherein the notification means notifies the control device when the remaining amount of the resource changes. The instruction means of the control device sends a handover instruction message instructing handover to a base station other than the notification source base station toward the notification source base station,
The base station
2. The transmission / reception means for receiving the transmitted handover instruction message and transmitting / receiving the received handover instruction message to at least one of the mobile terminals connected to the own station. The mobile communication system described. The instruction means of the control device sends a handover instruction message to a base station other than the notification source base station,
The base station
And a transmission / reception means for receiving the transmitted handover instruction message and transmitting the received handover instruction message to the mobile terminal connected to the notification source base station so as to be handed over to the own station. The mobile communication system according to claim 1. The controller is
Management means for managing, for each mobile terminal, identification information of a base station that is capturing radio waves, notified from each of the mobile terminals,
2. The mobile communication system according to claim 1, wherein the instruction unit determines a handover destination base station of the mobile terminal using identification information managed by the management unit. The controller is
Predicting means for predicting the other base station that is the handover destination based on the database,
2. The mobile communication according to claim 1, wherein the instructing unit instructs at least one of mobile communication terminals connected to the base station of the notification source to perform handover to the predicted base station. system. A plurality of base stations each accommodating an arbitrary number of mobile terminals wirelessly and installed without a station design, and a controller for concentrating these base stations and connecting them to a communication network,
The control device used in a mobile communication system for forming an area in a microcell system,
Receiving means for receiving from the base station a notification including information relating to a remaining amount of resources for wirelessly accommodating the mobile terminal and connecting to the communication network;
Based on the information on the remaining amount of the resource notified from the notification source base station, when the remaining amount of the resource of the notification source base station is compared with a specified value, Instructing means for instructing at least one of the mobile terminals connected to the notification source base station to perform handover to another base station;
A construction means for constructing a database indicating an adjacency relationship between the base stations based on radio field intensity from the plurality of base stations notified from each of the plurality of mobile terminals,
The control device, wherein the instruction unit specifies the other base station which is a handover destination using the database. 9. The control apparatus according to claim 8, wherein the instruction unit sends a handover instruction message instructing a handover to a base station other than the notification source base station toward the notification source base station. . 9. The control apparatus according to claim 8 , wherein the instruction unit transmits a handover instruction message to a base station other than the notification source base station. Furthermore, management means for managing, for each mobile terminal, identification information of a base station that is capturing radio waves, notified from each of the mobile terminals,
9. The control apparatus according to claim 8 , wherein the instruction unit determines a handover destination base station of the mobile terminal using identification information managed by the management unit. And further comprising prediction means for predicting the other base station as the handover destination based on the database ,
9. The control apparatus according to claim 8 , wherein the instructing unit instructs at least one mobile terminal connected to the notifying base station to perform handover to the predicted base station .

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