JP2004048490A - Mobile communication system, mobile communication network, and mobile communication terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To automatically and easily discover and cancel an area difficult in communication. <P>SOLUTION: A network controller 2 grasps the location of a communication terminal 3 based on the information from, for example, the terminal 3 when a prescribed event, such as a communication interruption, a fall in SIR environment, etc., caused as the communicating state between a base station 1 and the terminal 3 becomes worse. Then the controller 2 sets such a region that the base station 1 is difficult to normally communicate with the terminal 3 as a region to be formed by managing the occurring state of the event. To the region to be formed, the forming is performed from a different base station 1. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a mobile communication system that provides a mobile communication service, and a mobile communication network and a mobile communication terminal used in the mobile communication system.
[0002]
[Prior art]
In a mobile communication environment, a plurality of paths (multipaths) having different propagation times occur mainly due to the influence of a building or the like existing between a base station and a mobile communication terminal. Also, a plurality of waves arriving from various directions interfere with each other due to reflection or scattering at a building or the like existing near the mobile communication terminal, and a random standing wave called fading occurs. Multipath signals in one cell have unique fading fluctuations and interfere with each other. In the vicinity of the cell boundary, the influence of other-cell interference becomes large.
[0003]
Under these circumstances, there may be communication difficult areas where it is difficult to perform normal communication even in a cell.
[0004]
Conventionally, such a communication difficult area is found by a field survey by a system operator or a terminal maker, a complaint from an end user, or the like. Then, measures such as the addition of base stations have been taken so as to eliminate the difficult communication area that has been found.
[0005]
Further, when mobile communication terminals communicating with each other are concentrated in the same area, signals transmitted and received by the mobile communication terminals may interfere with each other, resulting in a deterioration in communication service quality.
[0006]
[Problems to be solved by the invention]
As described above, in the related art, the discovery of the difficult-to-communicate area and the measures for eliminating it have been performed manually. For this reason, there has been a problem that it takes a great deal of trouble to find a communication difficult area and take measures to eliminate it.
[0007]
In addition, the concentration of mobile communication terminals causes a problem that the quality of communication service is deteriorated due to interference between transmitted and received signals.
[0008]
The present invention has been made in view of such circumstances, and a first object of the present invention is to make it possible to automatically and easily find and solve a communication difficult area. is there.
[0009]
Another object of the present invention is to provide a high quality communication service even in an area where mobile communication terminals are concentrated.
[0010]
[Means for Solving the Problems]
In order to achieve the first object, a first invention provides a first base station for performing wireless communication with a mobile communication terminal located in a predetermined wireless zone, and a communication range in a wireless zone of the first base station. The first base station and the mobile station can perform beamforming to form the first base station and the mobile station in a mobile communication network including a second base station performing wireless communication with a mobile communication terminal located within the communication range. The position of the mobile communication terminal when a predetermined event occurs due to the deterioration of the communication state with the communication terminal is detected based on, for example, a notification from the mobile communication terminal, and the occurrence status of the event in each predetermined unit area Is managed. Further, in the mobile communication network, a unit area in which the managed event occurrence condition satisfies a predetermined condition is set as a forming target area, and a beam is transmitted to the second base station so that the forming target area is set as the communication area. Forming is performed.
[0011]
By taking such a measure, the position of the mobile communication terminal when a predetermined event occurs due to the deterioration of the communication state between the first base station and the mobile communication terminal in actual communication is determined by the mobile communication network. Be grasped. An area where it is difficult for the first base station to normally communicate with the mobile communication terminal is set as the forming target area based on the occurrence state of the event. Then, beamforming is performed on the forming target area from the second base station. Therefore, an area where communication with the first base station is difficult is treated so that communication with the second base station can be performed.
[0012]
According to a second aspect of the present invention, there is provided a first base station for performing wireless communication with a mobile communication terminal located in a predetermined wireless zone, and a first base station communicating within a wireless zone of the first base station. Beamforming can be performed to form a range, and the first base station and the first base station are wirelessly communicated in a mobile communication network including a second base station that performs wireless communication with a mobile communication terminal that is located within the communication range. Detecting the position of each of the mobile communication terminals that are performing communication, and setting a region where the mobile communication terminal that is performing wireless communication with the first base station exists a predetermined number or more within a predetermined region as a forming target region. I do. Further, in the mobile communication network, the second base station is made to perform beamforming so that the set forming target area is the communication area.
[0013]
By taking such means, the number of mobile communication terminals that are performing wireless communication with the first base station can be ascertained on the mobile communication network. An area where a predetermined number or more of mobile communication terminals performing wireless communication with the first base station are concentrated is set as the forming target area. Then, beamforming is performed on the forming target area from the second base station. Therefore, in the area where the mobile communication terminals are concentrated as described above, a state is set in which the first base station and the second base station can share the radio communication with the mobile communication terminals.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, some embodiments of the present invention will be described with reference to the drawings.
[0015]
(1st Embodiment)
FIG. 1 is a diagram showing an outline of the mobile communication system according to the first embodiment.
[0016]
As shown in FIG. 1, the mobile communication system includes a mobile communication network composed of a number of base stations 1 and a network control device 2, and a number of mobile communication terminals 3. In FIG. 1, only four base stations 1 are shown. In the following description and FIG. 1, especially when it is necessary to distinguish the individual base stations 1, they are represented as base stations 1-1, 1-2, 1-3, and 1-4, respectively. In FIG. 1, only two mobile communication terminals 3 are shown. In the following description and FIG. 1, especially when it is necessary to distinguish individual mobile communication terminals 3, they will be referred to as mobile communication terminals 3-1 and 3-2, respectively.
[0017]
The base station 1-1 connects the mobile communication terminal 3 to the mobile communication network by performing wireless communication with the mobile communication terminal 3 located within the range of the cell C indicated by the broken line in FIG.
[0018]
The base stations 1-2, 1-3, and 1-4 connect the mobile communication terminal 3 to a mobile communication network by performing wireless communication with the mobile communication terminal 3 located in a smaller communication range than the cell C. The base stations 1-2, 1-3, and 1-4 can perform beamforming so as to form a communication area at an arbitrary position within a predetermined forming range including a partial area of the cell C. A well-known technique can be used for this beam forming.
[0019]
Note that the base station 1-1 may also have a function of performing beamforming similarly to the base stations 1-2, 1-3, and 1-4. Further, the base stations 1-2, 1-3, and 1-4 may also have a function of forming a fixed cell similarly to the base station 1-1.
[0020]
FIG. 2 is a block diagram of a main part of the network control device 2.
[0021]
As shown in FIG. 2, the network control device 2 includes a communication control unit 21, a position information processing unit 22, a beamforming control unit 23, and a database 24.
[0022]
The communication control unit 21 is connected to each of the base stations 1. The communication control unit 21 controls communication between the base station 1 and communication between the base station 1 and another network (not shown) so that the mobile communication terminal 3 that performs wireless communication with the base station 1 performs communication. Be able to do it.
[0023]
The position information processing unit 22 uses the position information notified from the mobile communication terminal 3 to manage the position where a predetermined event occurs due to the deterioration of the communication state between the base station 1 and the mobile communication terminal 3. . For this management, the position information processing unit 22 uses a database 24.
[0024]
The beamforming control unit 23 detects the position of the communication difficult area based on the management result of the position information processing unit 22. The beamforming control unit 23 controls the base stations 1-2, 1-3, and 1-4 to perform beamforming to the detected communication difficult area.
[0025]
The database 24 records various types of information for managing the event occurrence status and the like.
[0026]
FIG. 3 is a block diagram of a main part of the mobile communication terminal 3.
[0027]
As shown in FIG. 3, the mobile communication terminal 3 includes an antenna 31, a radio unit 32, a signal processing unit 33, a transmission / reception unit 34, a GPS reception unit 35, a storage unit 36, and a control unit 37.
[0028]
The wireless unit 32 has a well-known configuration including, for example, a wireless transmission / reception unit, a modulation / demodulation unit, a transmission signal processing unit, and the like, and performs wireless communication with the base station 1 via the antenna 31 using, for example, a CDMA system. Various processing is performed to perform the processing.
[0029]
The signal processing unit 33 has a well-known configuration including an audio processing unit such as a vocoder and a PCM code processing unit, and a data communication unit such as a data transmission protocol processing unit, a data processing unit, and a data display unit.
[0030]
The transmission / reception unit 34 has a well-known configuration that performs processing such as generation of a transmission signal based on the transmission sound and reproduction of the reception sound based on the reception signal.
[0031]
The GPS receiving section 35 has a well-known configuration that receives a GPS signal transmitted from a GPS satellite (not shown) via the antenna 31 and performs the processing.
[0032]
The storage unit 36 stores information necessary for the control unit 37 to perform various processes.
[0033]
The control unit 37 controls the operations of the radio unit 32 and the signal processing unit 33 and realizes the operation as the mobile communication terminal 3 by exchanging control data with the base station 1. The control unit 37 also functions as a position notification unit 37a. The position notification unit 37a notifies the network control device 2 of a position so that the network control device 2 can determine its own position when the event occurs.
[0034]
Next, the operation of the mobile communication system configured as described above will be described.
[0035]
First, communication by the mobile communication terminal 3 is realized by a known operation. That is, for example, the mobile communication terminal 3 located in the cell C is basically connected to the mobile communication network by performing wireless communication with the base station 1-1, and communication is performed.
[0036]
When the mobile communication terminal 3 is in a state of performing communication, the control unit 37 of the mobile communication terminal 3 executes the processing shown in FIG. 4 at predetermined timings such as at predetermined time intervals.
[0037]
In this process, the control unit 37 first checks in step ST1 and step ST2 whether a communication disconnection has occurred or a low SIR environment has occurred. Then, if none of the above applies, the control unit 37 ends the processing of FIG.
[0038]
Now, when the mobile communication terminal 3 during communication enters an area where communication with the base station 1 cannot be maintained due to shadowing, goes out of the cell, or when BLER degradation occurs due to a low SIR environment. In some cases, communication disconnection may occur. If it is confirmed in step ST1 that such a communication disconnection has occurred, in step ST3, the control unit 37 acquires GPS information from the GPS receiving unit 35 and stores it in the storage unit 36.
[0039]
Then, in step ST4, the control unit 37 waits for communication with the base station 1 to be enabled. After confirming that communication with the base station 1 is enabled, the control unit 37 sends the position information based on the GPS information stored in the storage unit 36 to the network control device 2 in step ST5. Notice. The position information may be coordinate information such as longitude and latitude information obtained from PGPS information or the like, or may be information for obtaining such coordinate information.
[0040]
On the other hand, when the mobile communication terminal 3 during communication enters an area where interference from other cells or multipath interference is large, although a communication disconnection does not occur, a low SIR environment requiring excessive power may occur. If it is confirmed in step ST2 that such a low SIR environment has occurred, the control unit 37 acquires GPS information from the GPS receiving unit 35 in step ST6. Then, in step ST7, the control unit 37 notifies the network control device 2 of the location information based on the acquired GPS information.
[0041]
The position information processing unit 22 in the network control device 2 executes the processing shown in FIG. 5 at predetermined timings, such as at predetermined time intervals.
[0042]
In this process, first, in step ST11, the position information processing unit 22 checks whether or not a position notification has been made from the mobile communication terminal 3. Then, when it is confirmed that the position notification has not been performed, the position information processing unit 22 ends the processing of FIG.
[0043]
Now, as described above, if the mobile communication terminal 3 notifies the network control device 2 of the position information, the position information processing unit 22 confirms that in step ST11. Then, in this case, the position information processing unit 22 acquires the notified position information via the communication control unit 21 in step ST12. Subsequently, in step ST13, the position information processing unit 22 adds a data record including the obtained position information and time information indicating the current time to the database 24.
[0044]
As described above, every time an event such as a communication disconnection or a decrease in SIR occurs in the mobile communication terminal 3, the position information indicating the position of the mobile communication terminal 3 at that time is accumulated in the database 24.
[0045]
In such a situation, the beamforming control unit 23 executes the processing shown in FIG. 6 at predetermined timings such as at predetermined time intervals.
[0046]
In this process, the beamforming control unit 23 first analyzes the database 24 in step ST21, and statistically specifies a communication difficult area. Subsequently, in step ST22, the beamforming control unit 23 checks whether or not there is a communication difficult area. Then, when it is confirmed that there is no communication difficult area, the beamforming control unit 23 ends the processing of FIG.
[0047]
If it is confirmed that there is a difficult communication area, the beamforming control unit 23 checks in step ST23 whether the difficult communication area has already been set as the forming target area. If the communication difficult area is newly discovered, the communication difficult area is not set as the forming target area. Thus, if it is confirmed that the difficult communication area is not set as the forming target area, the beam forming control unit 23 sets the difficult communication area as the forming target area in step ST24.
[0048]
Next, in step ST25, the beamforming control unit 23 selects, as a forming base station candidate, a base station whose forming target area is within an area where beamforming is possible. Specifically, the example of FIG. 1 shows an example in which the area E in the cell C is a communication difficult area due to shadowing by the building B1. In this example, base stations 1-2, 1-3, and 1-4 exist as areas in which the area E including the area E can be subjected to beamforming. In this case, in step ST25, the beamforming control unit 23 selects the base stations 1-2, 1-3, and 1-4 as forming base station candidates.
[0049]
Subsequently, in step ST26, the beamforming control unit 23 checks whether or not there is a base station 1 that has not been selected among the forming base station candidates. Here, if it is confirmed that there is an unselected base station 1, the beamforming control unit 23 selects one of the unselected base stations 1 in step ST27. Then, in step ST28, the beamforming control unit 23 causes the selected base station 1 to start beamforming to the forming target area. Then, in step ST29, the beamforming control unit 23 excludes, from the database 24, data used for determining the area in which the beamforming has started this time as the communication difficult area. That is, since the communication conditions change in the area where the beamforming is started this time, the data accumulated for the area is excluded.
[0050]
In this way, the setting is made so that beamforming is performed from another base station 1 in order to cover an area where communication between a certain base station 1 and the mobile communication terminal 3 becomes difficult. However, it is not guaranteed whether the beamforming enables communication in a communication difficult area. That is, for example, in the example of FIG. 1, when beamforming from the base station 1-2 or the base station 1-3 to the area E is blocked by the buildings B2 and B3, the mobile communication terminal located in the area E 3 cannot communicate well with the base stations 1-2 and 1-3.
[0051]
In such a case, the communication difficult area is still not resolved. When this state continues for a while, data on the occurrence of an event in that area is accumulated in the database 24. As a result, the beamforming control unit 23 confirms that there is a communication difficult area in step ST22. The difficult communication area found at this time is already set as the forming target area. Therefore, the beamforming control unit 23 confirms in step ST23 that the communication difficult area has already been set as the forming target area. In this case, the beamforming control unit 23 does not perform the processing of steps ST24 and ST25 described above, and shifts the processing from step ST23 to step ST26. Then, the beamforming control unit 23 repeats the processing after step ST26 in the same manner as described above. Thereby, if the base station 1 still remains unselected, the base station 1 that performs beamforming is changed.
[0052]
Then, if the base station 1 that can communicate with the forming target area, such as the base station 1-4 in FIG. 1, performs beamforming, the forming target area is no longer a communication difficult area.
[0053]
If beamforming is not performed even if beamforming is performed from all base stations 1 selected as forming base station candidates, beamforming control section 23 determines that there is no unselected base station in step ST26. Will be confirmed. In this case, it is difficult to eliminate the communication difficult area by the beamforming from the existing base station 1, and therefore, in step ST30, the beamforming control unit 23 notifies the administrator, for example, to that effect. Perform error processing such as
[0054]
As described above, according to the first embodiment, an area in which communication between a certain base station 1 and a mobile communication terminal 3 becomes difficult is automatically found by accumulating and managing an event occurrence state. . The communication difficult area is covered by performing beamforming from another base station 1 and is an area where communication can be performed. Therefore, almost no manpower is required for investigating an area where communication is difficult and for taking measures to eliminate it.
[0055]
Further, according to the first embodiment, when there are a plurality of base stations 1 in which a communication difficult area is an area where beamforming can be performed, it is automatically determined which of the base stations 1 performs beamforming. . As a result, no manual intervention is required in this regard.
[0056]
According to the first embodiment, the mobile communication terminal 3 notifies the network control device 2 of the position for managing the event occurrence position from the mobile communication terminal 3 unilaterally. As a result, there is no need to issue a position notification request from the network control device 2, and the burden on the network control device 2 can be reduced.
[0057]
Further, according to the first embodiment, the position when the communication disconnection occurs is stored in the mobile communication terminal 3, and after the communication is enabled, the above-mentioned storage is transferred from the mobile communication terminal 3 to the network control device 2. Notify the location you set. As a result, the network control device 2 can accurately grasp the position of the mobile communication terminal 3 where the communication disconnection has occurred, and can specify a communication difficult area with a small error.
[0058]
(Second embodiment)
The mobile communication system according to the second embodiment has the same hardware configuration as the mobile communication system according to the first embodiment. The mobile communication system according to the second embodiment differs from the first embodiment in that the processes of the position information processing unit 22, the beamforming control unit 23, and the control unit 37 perform the following operations.
[0059]
The position information processing unit 22 executes the processing shown in FIG. 7 at predetermined timings such as at predetermined time intervals.
[0060]
In this process, first, in step ST31, the position information processing unit 22 checks whether or not a communication disconnection has occurred with any of the mobile communication terminals 3 that were communicating. If it is confirmed that the communication disconnection has not occurred, the position information processing unit 22 requests the mobile communication terminal 3 in communication with a position notification in step ST32.
[0061]
The control unit 37 of the mobile communication terminal 3 that is performing communication performs the process shown in FIG. 8 at a predetermined timing such as at a predetermined time interval.
[0062]
In this process, first, in step ST41, the control unit 37 confirms whether or not the above-described position notification request has been made from the mobile communication network side. If the request for the position notification has not been made, the control unit 37 ends the processing of FIG.
[0063]
However, if it is confirmed that the request for the position notification has been made from the mobile communication network side as described above, the control unit 37 acquires the GPS information from the GPS receiving unit 35 in step ST42. Then, in step ST43, the control unit 37 notifies the network control device 2 of the location information based on the acquired GPS information.
[0064]
Then, after requesting the position notification in step ST32, the position information processing unit 22 acquires the position information notified from the mobile communication terminal 3 via the communication control unit 21 in step ST33 as described above. Then, in step ST34, the position information processing unit 22 holds the obtained position information as the latest position information.
[0065]
Subsequently, in step ST35, the position information processing unit 22 checks whether or not a request for excess power has been made from the mobile communication terminal 3 that has notified the acquired position information. If it is confirmed that the request for excess power has been made, the position information processing unit 22 adds a data record including the obtained position information and time information indicating the current time to the database 24 in step ST36. I do. If it is confirmed in step ST35 that the request for excess power has not been made, the position information processing section 22 passes the processing in step ST36.
[0066]
As described above, the position of the mobile communication terminal 3 in the low SIR environment is periodically grasped by the network control device 2, and the position information indicating the position is accumulated in the database 24.
[0067]
On the other hand, if it is confirmed in step ST31 that the communication disconnection has occurred, in step ST37, the position information processing unit 22 outputs the position information held as the latest position information and the time information indicating the current time. Is added to the database 24.
[0068]
As described above, with respect to the mobile communication terminal 3 from which the communication disconnection has occurred, the position information indicating the latest one of the positions periodically grasped by the network control device 2 during communication is accumulated in the database 24. go.
[0069]
Now, the beamforming control unit 23 executes the processing shown in FIG. 9 at predetermined timings such as at predetermined time intervals. The processing shown in FIG. 9 is executed for each of the base stations 1 having the function of performing beamforming (hereinafter, referred to as target base stations). The interval at which the processing shown in FIG. 9 is performed may be longer than the interval at which the processing shown in FIGS. 7 and 8 is performed.
[0070]
First, in step ST51, the beamforming control unit 23 causes the target base station 1 to start beamforming. Note that an area to be initially subjected to beamforming is predetermined for each base station 1.
[0071]
Next, in step ST52 and step ST54, the beamforming control unit 23 determines whether a predetermined time has elapsed since the start of beamforming for one area or that communication between the target base station 1 and the mobile communication terminal 3 occurs. Await.
[0072]
In this state, if it is confirmed in step ST53 that communication between the target base station 1 and the mobile communication terminal 3 has occurred, the beamforming control unit 23 determines in step ST54 the area in which the target base station 1 is forming. Register as a communicable area. However, if it is confirmed that the fixed time has elapsed without the occurrence of communication between the target base station 1 and the mobile communication terminal 3, the beamforming control unit 23 passes the process of step ST54. That is, in this case, the beamforming control unit 23 does not set the area in which the target base station 1 is forming as the communicable area.
[0073]
Subsequently, in step ST55, the beamforming control unit 23 confirms whether or not the scan has been completed. Then, if it is confirmed that the scanning has not been completed yet, in step ST56, the beamforming control unit 23 changes the area to which the target base station 1 performs beamforming. The order of the areas to be subjected to beamforming is determined in advance for each base station 1.
[0074]
Then, the beamforming control unit 23 repeats the processing after step ST52. That is, the beamforming control unit 23 performs a scan operation for confirming whether communication is possible in each area while gradually changing the area to be subjected to beamforming. When it is determined that communication is possible in all areas to be scanned, the beamforming control unit 23 determines in step ST55 that scanning has been completed, and ends the processing in FIG.
[0075]
On the other hand, as described above, while the position information indicating the position of the mobile communication terminal 3 at the time when the event such as the communication disconnection and the decrease in the SIR occurs in the mobile communication terminal 3 by the position information processing unit 22, The beamforming control unit 23 executes the process shown in FIG. 10 at predetermined timings, such as at predetermined time intervals. The processing shown in FIG. 10 is performed asynchronously with the processing shown in FIG. 9, and is usually performed more frequently than the processing shown in FIG.
[0076]
In this process, the beamforming control unit 23 first analyzes the database 24 in step ST61 and statistically specifies a communication difficult area. Subsequently, in step ST62, the beamforming control unit 23 confirms whether or not there is a communication difficult area. Then, when it is confirmed that there is no communication difficult area, the beamforming control unit 23 ends the processing of FIG.
[0077]
When confirming that there is a difficult communication area, the beamforming control unit 23 checks in step ST63 whether the difficult communication area has already been set as the forming target area. If the communication difficult area is newly discovered, the communication difficult area is not set as the forming target area. Therefore, if it is confirmed that the difficult communication area is not set as the forming target area, the beamforming control unit 23 sets the difficult communication area as the forming target area in step ST64.
[0078]
Next, in step ST65, the beamforming control unit 23 selects one base station 1 in which the forming target area is registered as a communicable area.
[0079]
Subsequently, in step ST66, the beamforming control unit 23 confirms whether or not there is a corresponding base station 1 in step ST65. Then, when it is confirmed that the corresponding base station 1 exists, in step ST67, the beamforming control unit 23 causes the selected base station 1 to start beamforming to the forming target area. Then, in step ST68, the beamforming control unit 23 excludes, from the database 24, the data used to determine the area where the beamforming has started this time as the communication difficult area. That is, since the communication conditions change in the area where the beamforming is started this time, the data accumulated for the area is excluded.
[0080]
In this way, the setting is made so that beamforming is performed from another base station 1 in order to cover an area where communication between a certain base station 1 and the mobile communication terminal 3 becomes difficult.
[0081]
If no corresponding base station 1 is found in step ST65, it is difficult to eliminate the communication difficult area by beamforming from the existing base station 1. Then, if it is confirmed in step ST66 that there is no corresponding base station, in step ST69, the beamforming control unit 23 performs an error process such as notifying the administrator of the fact.
[0082]
As described above, according to the second embodiment, an area in which communication between a certain base station 1 and a mobile communication terminal 3 becomes difficult is automatically found by accumulating and managing an event occurrence state. . The communication difficult area is covered by performing beamforming from another base station 1 and is an area where communication can be performed. Therefore, almost no manpower is required for investigating an area where communication is difficult and for taking measures to eliminate it.
[0083]
According to the second embodiment, when there are a plurality of base stations 1 in which the communication difficult area is an area where beamforming can be performed, it is automatically determined which of the base stations 1 should perform beamforming. Therefore, no manual intervention is required in this regard.
[0084]
Further, according to the second embodiment, the base station 1 is caused to scan the beamforming operation in advance, and an area where beamforming can be performed by each base station 1 is detected and registered. Then, when a communication difficult area is found, the base station 1 in which the area is registered as a communicable area performs beamforming. Therefore, if a difficult communication area is found, the area can be immediately covered by beamforming, and the difficult communication area can be eliminated quickly.
[0085]
Further, according to the second embodiment, the management relating to the event occurrence is entirely performed by the network control device 2. As a result, the mobile communication terminal 3 only needs to perform position notification in response to a request from the network control device 2, and the burden on the mobile communication terminal 3 is reduced as compared with the first embodiment.
[0086]
Further, according to the second embodiment, the network control device 2 determines the position of the mobile communication terminal 3 where the communication disconnection occurred as the latest position notified before the communication disconnection. As a result, the burden on the mobile communication terminal 3 side is reduced as compared with the first embodiment.
[0087]
(Third embodiment)
The mobile communication system according to the third embodiment has the same hardware configuration as the mobile communication system according to the first embodiment. The mobile communication system according to the third embodiment differs from the first embodiment in that the processes of the position information processing unit 22 and the beamforming control unit 23 perform the following operations.
[0088]
The position information processing unit 22 executes the processing shown in FIG. 11 at predetermined timings such as at predetermined time intervals.
[0089]
In this process, the position information processing section 22 first confirms in step ST71 whether or not a position notification has been made from the mobile communication terminal 3. Then, when it is confirmed that the position notification has not been performed, the position information processing section 22 ends the processing of FIG.
[0090]
Now, as described in the first embodiment, if the mobile communication terminal 3 notifies the network control device 2 of the position information, the position information processing unit 22 confirms that in step ST71. It becomes. In this case, in step ST72, the position information processing unit 22 acquires the notified position information via the communication control unit 21.
[0091]
Subsequently, in step ST73, the position information processing unit 22 updates the database 24 based on the acquired position information. The database 24 in the third embodiment manages the respective positions of the mobile communication terminals 3 that are communicating with each base station 1 unlike the first embodiment.
[0092]
In this way, based on the notification from the mobile communication terminal 3, the respective positions of the mobile communication terminals 3 that are currently communicating are described in the database 24.
[0093]
In such a case, the beamforming control unit 23 executes the processing shown in FIG. 12 at predetermined timings such as at predetermined time intervals.
[0094]
In this process, the beamforming control unit 23 first analyzes the database 24 in step ST81, and specifies the distribution of mobile communication terminals that are communicating. Subsequently, in step ST82, the beamforming control unit 23 confirms whether or not there is a terminal concentration area based on the result of the above analysis. The terminal concentration area is an area in which a predetermined number or more of mobile communication terminals 3 that are communicating within an area of a predetermined size exist.
[0095]
If it is confirmed that there is a terminal concentration area, in step ST83, the beamforming control unit 23 confirms whether beamforming for the terminal concentration area has already been performed. Then, if it is confirmed that the beam forming for the terminal concentration area has not been performed yet, the beamforming control unit 23 determines in step ST84 whether the terminal concentration area has already been set as the forming target area. Check. If the terminal concentration area is newly discovered, the terminal concentration area is not set as the forming target area. Therefore, if it is confirmed that the terminal concentration area is not set as the forming target area, the beamforming control unit 23 sets the terminal concentration area as the forming target area in step ST85.
[0096]
Next, in step ST86, the beamforming control unit 23 selects the base station 1 whose forming target area is within the area where beamforming is possible as a forming base station candidate. Subsequently, in step ST87, the beamforming control unit 23 confirms whether or not there is a base station which has not been selected among the forming base station candidates. Here, if it is confirmed that there is an unselected base station 1, the beamforming control unit 23 selects one of the unselected base stations 1 in step ST88. Then, in step ST89, the beamforming control unit 23 causes the selected base station 1 to start beamforming to the forming target area.
[0097]
In this way, the setting is made so that beamforming is performed from another base station 1 so as to cover the area where the mobile communication terminals 3 during communication are concentrated. However, it is not guaranteed whether communication between the base station 1 performing this beamforming and the mobile communication terminal 3 located in the terminal concentration area becomes possible.
[0098]
In the case where an obstacle is present between the base station 1 that performs beamforming and the terminal concentration area, the terminal concentration area is still not resolved. Therefore, the beamforming control unit 23 confirms again that there is a terminal concentration area in step ST82. The terminal concentration area found at this time is already set as the forming target area. Therefore, the beamforming control unit 23 confirms in step ST83 that the terminal concentration area has already been set as the forming target area. In this case, the beamforming control unit 23 shifts the processing from step ST83 to step ST87 without performing the processing of step ST85 and step ST86 described above. Then, the beamforming control unit 23 repeats the processing after step ST87 in the same manner as described above. Thereby, if the base station 1 still remains unselected, the base station 1 that performs beamforming is changed.
[0099]
Then, when the base station 1 capable of communicating with the forming target area starts performing beam forming, the mobile communication terminal 3 communicating in the forming target area becomes different from the base station 1 that has been communicating so far. It is possible to perform communication with the base station 1 that performs beamforming.
[0100]
Regarding the area where the beamforming has been started in this way, measures have already been taken even if the area becomes a terminal concentration area thereafter. Therefore, when it is confirmed in step ST83 that the beam forming has already been performed for the terminal concentration area, the beam forming control unit 23 performs the processing in FIG. 12 without performing the processing after step ST84. finish.
[0101]
Note that if the terminal concentration area is not resolved even if beamforming is performed from all base stations 1 selected as forming base station candidates, the beamforming control unit 23 determines that there is no unselected base station 1 in step ST87. That will be confirmed. In this case, it is difficult to eliminate the terminal concentration area by the beamforming from the existing base station 1, and therefore, in step ST90, the beamforming control unit 23 notifies the administrator, for example, to that effect. Perform error processing such as
[0102]
By the way, when it is confirmed in step ST82 that there is no terminal concentration area, in step ST91, the beamforming control unit 23 confirms whether or not there is an area where beamforming is performed. Then, when it is confirmed that there is a corresponding area, in step ST92, the beam forming control unit 23 stops the beam forming for the area.
[0103]
As described above, according to the third embodiment, the area where the number of mobile communication terminals 3 communicating with a certain base station 1 is large is determined by the network control device 2 based on the position notification from each mobile communication terminal 3. Discovered automatically. The terminal concentration area is covered by performing beamforming from another base station 1. As a result, the communication of a large number of mobile communication terminals 3 is shared by the two base stations 1, so that the transmission power is reduced and the frequency use efficiency is improved.
[0104]
Note that the present invention is not limited to the above embodiments. For example, in the second embodiment, the position notification from the mobile communication terminal 3 to the network control device 2 may be periodically performed from the mobile communication terminal 3 without making a request from the network control device 2.
[0105]
In the second embodiment, the position information processing unit 22 may estimate the event occurrence position by estimating the moving state of the mobile communication terminal 3 based on a plurality of pieces of position information acquired in the past.
[0106]
In the second embodiment, a condition for determining a communication-possible area during scanning can be arbitrarily determined, for example, “when a plurality of communications occur”.
[0107]
In the third embodiment, notification of position information for monitoring concentration of the mobile communication terminals 3 may be performed in response to a request from the network control device 2. In this case, the request may be made periodically or when a condition such as "when the number of communicating terminals exceeds a predetermined number" is satisfied.
[0108]
Also in the third embodiment, selection of a base station for performing beamforming may be performed as in the second embodiment.
[0109]
The processing of the position information processing unit 22 and the control unit 37 in the first embodiment and the processing of the beamforming control unit 23 in the second embodiment can be performed in combination. Conversely, the processing of the position information processing unit 22 and the control unit 37 in the second embodiment and the processing of the beamforming control unit 23 in the first embodiment can be performed in combination.
[0110]
It is also possible to implement the first embodiment or the second embodiment in combination with the third embodiment.
[0111]
In each embodiment, the position detection in the mobile communication terminal 3 is not limited to using the GPS, but may be performed by another method.
[0112]
In each embodiment, one base station 1 that performs beamforming on a certain area may be specified in advance.
[0113]
In each embodiment, a part of the functions provided in the network control device 2 may be provided in another part of the mobile communication network such as the base station 1.
[0114]
Further, in order to achieve the same operation and effect as in the first embodiment, the function of the control unit 37 shown in the first embodiment can be provided in the base station. In this case, the base station checks whether a communication disconnection has occurred or a low SIR environment has occurred. The base station transmits the position information of the mobile communication terminal from the base station to the mobile communication terminal when the communication with the mobile communication terminal is restored when the communication disconnection occurs, and when the low SIR environment is established. Request, and the base station receives a position notification from the mobile communication terminal. Then, based on the position information obtained here, the base station finds a communication difficult area.
[0115]
In addition, various modifications can be made without departing from the spirit of the present invention.
[0116]
【The invention's effect】
According to the first invention, the position of the mobile communication terminal at the time of occurrence of a predetermined event caused by deterioration of the communication state between the first base station and the mobile communication terminal in actual communication is grasped by the mobile communication network. . An area where it is difficult for the first base station to normally communicate with the mobile communication terminal is set as the forming target area based on the event occurrence situation. Then, beamforming is performed on the forming target area from the second base station. Therefore, an area where communication with the first base station is difficult is treated so that communication with the second base station can be performed. As a result, the detection of a communication difficult area and its elimination are automatically and easily performed. It is possible to do it.
[0117]
Further, according to the second aspect, the number of mobile communication terminals that are performing wireless communication with the first base station is grasped on the mobile communication network. An area where a predetermined number or more of mobile communication terminals performing wireless communication with the first base station are set as a forming target area. Then, beamforming is performed on the forming target area from the second base station. Therefore, in the area where the mobile communication terminals are concentrated as described above, a state is set in which the first base station and the second base station can share the radio communication with the mobile communication terminals. Thus, it is possible to provide a high quality communication service even in an area where mobile communication terminals are concentrated.
[Brief description of the drawings]
FIG. 1 is a diagram showing an outline of a mobile communication system according to a first embodiment.
FIG. 2 is a block diagram of a main part of the network control device 2;
FIG. 3 is a block diagram of a main part of the mobile communication terminal 3.
FIG. 4 is a flowchart of a process of a control unit 37 in the first embodiment.
FIG. 5 is a flowchart of processing of a position information processing unit 22 according to the first embodiment.
FIG. 6 is a flowchart of a process performed by a beam forming control unit 23 according to the first embodiment.
FIG. 7 is a flowchart of a process of a position information processing unit 22 according to the second embodiment.
FIG. 8 is a flowchart of a process of a control unit 37 according to the second embodiment.
FIG. 9 is a flowchart of a process performed by a beam forming control unit 23 according to the second embodiment.
FIG. 10 is a flowchart of a process performed by a beam forming control unit 23 according to the second embodiment.
FIG. 11 is a flowchart of a process performed by a position information processing unit 22 according to the third embodiment.
FIG. 12 is a flowchart of a process performed by a beam forming control unit 23 according to the third embodiment.
[Explanation of symbols]
1 (1-1, 1-2, 1-3, 1-4) ... base station
2. Network control device
3 (3-1, 3-2): Mobile communication terminal
21 Communication control unit
22 Position information processing unit
23: Beam forming control unit
24 ... Database
31 ... antenna
32 ... Wireless unit
33 ... Signal processing unit
34 ... Transmission and reception unit
35 ... GPS receiver
36 ... Storage unit
37 ... Control unit
37a ... Location notification unit

Claims (26)

A first base station that performs wireless communication with a mobile communication terminal located in a predetermined wireless zone;
A second base station capable of performing beamforming so as to form a communication range in a wireless zone of the first base station, and performing wireless communication with a mobile communication terminal located in the communication range;
Detecting means for detecting a position of the mobile communication terminal when a predetermined event occurs due to deterioration of a communication state between the first base station and the mobile communication terminal;
Management means for managing the occurrence status of the event for each predetermined unit area based on the detection result of the detection means,
Setting means for setting, as a forming target area, a unit area in which the occurrence state of an event managed by the management means satisfies a predetermined condition;
A mobile communication network comprising: control means for causing the second base station to perform beamforming such that the forming target area set by the setting means is used as the communication area. The mobile communication network according to claim 1, wherein the detection unit detects a position of the mobile communication terminal when the event occurs based on position information notified from the mobile communication terminal. The event is that communication between the first base station and the mobile communication terminal is disconnected due to deterioration of a communication state,
The detecting means receives, from the mobile communication terminal in which the event has occurred, a notification of position information relating to a position at which the event has occurred after the event has been resolved, and generates the event based on the notified position information. The mobile communication network according to claim 2, wherein the mobile communication terminal detects a position of the mobile communication terminal when the mobile communication terminal performs the operation. A mobile communication terminal that performs communication via the mobile communication network according to claim 3,
Acquisition means for acquiring location information about the current location of the user,
Storage means for storing the position information obtained by the obtaining means as relating to the current position when the event occurs,
Notification means for notifying the mobile communication network of location information stored by the storage means in response to the event being resolved and connection to the mobile communication network being enabled. Communication terminal. A mobile communication system comprising the mobile communication network according to claim 3 and the mobile communication terminal according to claim 4. The detecting means receives a notification of position information periodically made from the mobile communication terminal, and detects a position of the mobile communication terminal when the event occurs based on the position information notified before the event occurs. 3. The mobile communication network according to claim 2, wherein A mobile communication terminal that performs communication via the mobile communication network according to claim 6,
Acquisition means for acquiring location information about the current location of the user,
A mobile communication terminal comprising: a notification unit that periodically notifies the mobile communication network of the position information acquired by the acquisition unit when performing wireless communication with the first base station. A mobile communication system comprising the mobile communication network according to claim 6 and the mobile communication terminal according to claim 7. Requesting means for periodically requesting notification of position information to a mobile communication terminal performing wireless communication with the first base station,
And the detecting means receives a notification of the position information made from the mobile communication terminal in response to the request by the requesting means, and when the event occurs based on the position information notified before the occurrence of the event. The mobile communication network according to claim 2, wherein the position of the mobile communication terminal is detected. A mobile communication terminal performing communication via the mobile communication network according to claim 9,
Acquisition means for acquiring location information about the current location of the user,
A mobile communication terminal comprising: a notifying unit that notifies the mobile communication network of the position information acquired by the acquiring unit in response to a request by the requesting unit. A mobile communication system comprising the mobile communication network according to claim 9 and the mobile communication terminal according to claim 10. The event is that the communication quality is reduced below a predetermined quality,
Requesting means for requesting notification of location information to the mobile communication terminal in which the event has occurred,
And the detecting means receives a notification of the position information made from the mobile communication terminal in response to the request by the requesting means, and when the event occurs based on the position information notified before the occurrence of the event. The mobile communication network according to claim 2, wherein the position of the mobile communication terminal is detected. A mobile communication terminal that performs communication via the mobile communication network according to claim 12,
Acquisition means for acquiring location information about the current location of the user,
A mobile communication terminal comprising: a notifying unit that notifies the mobile communication network of the position information acquired by the acquiring unit in response to a request by the requesting unit. A mobile communication system comprising the mobile communication network according to claim 12 and the mobile communication terminal according to claim 13. The event is that the communication quality is reduced below a predetermined quality,
And the detecting means receives a notification of the position information made from the mobile communication terminal when the event occurs, and determines the position of the mobile communication terminal when the event occurs based on the notified position information. The mobile communication network according to claim 2, which detects. A mobile communication terminal performing communication via the mobile communication network according to claim 15,
Acquisition means for acquiring location information about the current location of the user,
When a predetermined event occurs in which the communication quality with the first base station drops below a predetermined quality, the mobile station notifies the mobile communication network of the position information acquired by the acquisition unit at that time. A mobile communication terminal comprising a notification unit. A mobile communication system comprising the mobile communication network according to claim 15 and the mobile communication terminal according to claim 16. A first base station that performs wireless communication with a mobile communication terminal located in a predetermined wireless zone;
A second base station capable of performing beamforming so as to form a communication range in a wireless zone of the first base station, and performing wireless communication with a mobile communication terminal located in the communication range;
Detecting means for detecting a position of each of the mobile communication terminals performing wireless communication with the first base station;
Setting means for setting, as a forming target area, an area in which the mobile communication terminal performing wireless communication with the first base station is present in a predetermined number or more within a predetermined area, based on a detection result of the detecting means;
A mobile communication network comprising: control means for causing the second base station to perform beamforming such that the forming target area set by the setting means is used as the communication area. The detecting means receives a notification of position information periodically made from the mobile communication terminal, and based on the notified position information, the mobile communication terminal based on the position information notified before the event occurs. 19. The mobile communication network according to claim 18, wherein the respective positions of the mobile communication network are detected. A mobile communication terminal performing communication via the mobile communication network according to claim 19,
Acquisition means for acquiring location information about the current location of the user,
A mobile communication terminal comprising: a notification unit that periodically notifies the mobile communication network of the position information acquired by the acquisition unit when performing wireless communication with the first base station. A mobile communication system comprising the mobile communication network according to claim 19 and the mobile communication terminal according to claim 20. Requesting means for requesting, at a predetermined timing, notification of position information to a mobile communication terminal performing wireless communication with the first base station,
And the detecting means receives a notification of the position information made from the mobile communication terminal in response to the request by the requesting means, and when the event occurs based on the position information notified before the occurrence of the event. The mobile communication network according to claim 2, wherein the position of the mobile communication terminal is detected. A mobile communication terminal performing communication via the mobile communication network according to claim 22,
Acquisition means for acquiring location information about the current location of the user,
A mobile communication terminal comprising: a notifying unit that notifies the mobile communication network of the position information acquired by the acquiring unit in response to a request by the requesting unit. A mobile communication system comprising the mobile communication network according to claim 22 and the mobile communication terminal according to claim 23. When there are a plurality of the second base stations in which the forming target area is within a range in which the beam forming can be performed, the control unit sequentially transmits the forming target areas to the second base stations in the communication area. The beamforming is performed as follows, and at that time, the second base station capable of performing communication with the mobile communication terminal is determined as performing beamforming to the forming target area. The mobile communication network according to claim 18. Search means for searching for an area where the second base station can communicate with the mobile communication terminal while sequentially changing the communication area of the second base station,
The control unit can perform communication with the mobile communication terminal by the search unit when there is a plurality of the second base stations in which the forming target area is within a range in which beamforming can be performed. The mobile communication network according to claim 1 or 18, wherein a second base station whose area determined to be the same as the forming target area is determined to perform beamforming to the forming target area.

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