JP3366810B2 - Mobile communication system - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a mobile communication system.

[0002]

2. Description of the Related Art Conventionally, in order to smoothly and efficiently provide a communication service using a mobile device such as a mobile phone, a telecommunications carrier has called a radio base station (hereinafter referred to as "fixed base station") in a service area. ) Is optimized (zone configuration or sector configuration) before and after construction of the mobile communication network.

If the number of channels in a certain area (zone or sector) is insufficient as a result of this investigation / study, the telecommunications carrier increases the number of channels available in the area (in the area). The fixed base station has been added to the above), and efforts are being made to maintain a sufficient number of channels.

[0004]

However, no matter how meticulously investigated and studied and the zone (sector) configuration is optimized, there are cases where it is not possible to sufficiently cope with the instantaneous generation of a large amount of traffic. For example, if a sudden event / accident or disaster occurs in a certain area, or if a large number of people gather in a certain area, mobile devices will concentrate in that area and the capacity of fixed base stations (number of channels) will be temporarily increased. Traffic that exceeds the limit may occur.

In the case of a fixed communication network, since the communication terminals do not move and the number of communication terminals under the control of one exchange does not change in the short term, it is possible to know in advance the maximum traffic volume that can occur. However, in the mobile communication network, it is not possible to know in advance the maximum amount of traffic that can be generated in each fixed base station due to the fatal characteristic of mobile communication that "mobile devices can move freely".

Of course, if the capacity of each fixed base station is made extremely large and it is possible to sufficiently process even when all the mobile stations communicate simultaneously, it is possible to cope with the concentration of traffic due to a sudden event. It is unrealistic to deploy a large number of fixed base stations, and in the first place, how is TDMA (Time Division Multiple Access), CD
Even if MA (Code Division Multiple Access) technology advances, it still requires an unrealistically wide range of frequency bands, which is unrealizable in practice.

[0007] After all, there is no conventional technology that essentially solves the occurrence of a communication incommunicable state due to temporary congestion resulting from the fatal characteristic of mobile communication that "a mobile device can move freely". However, at the time of congestion, the user of the mobile device is forced to refrain from using the mobile device in the congestion area. However, in general, the communication at the time of a sudden event occurrence is often urgent, and the situation where the mobile device cannot be used immediately or communication is required after moving to another area is caused by the public. The convenience of mobile communication that "communicate anytime, anywhere" without queuing the queues of telephones is seriously impaired.

The present invention has been made under such a background, and it is an object of the present invention to provide a mobile communication system capable of preventing the occurrence of a communication-disabled state due to temporary congestion without increasing the cost. Has an aim.

[0009]

Means for Solving the Problems] To solve the problems described above, the mobile communication system according to claim 1 is present in a plurality of fixed base stations connected to the network and the plurality of fixed base station area in the mobile communication system and mobile station communicate via a radio channel, said plurality of fixed base
Of the ground stations, the first fixed base station with congestion is detected.
Used by the first detecting means for outputting and the first fixed base station
The wireless channel that does not interfere with the wireless channel that is being used is set, and the wireless channel of the first fixed base station
A mobile base station moving in the air, which communicates with a mobile device existing in the area, and a detection result by the first detection means.
And a control device for controlling the movement of the mobile base station based on
It is characterized by being equipped .

A mobile communication system according to a second aspect is a mobile communication system in which a plurality of fixed base stations connected to a network and mobile stations existing in the areas of the plurality of fixed base stations communicate via a radio channel. , The plurality of solid
Of the fixed base stations, the first fixed base station in which congestion has occurred
Of the plurality of fixed base stations,
Of which, it is possible to communicate with mobile relay stations
And is not used by the first fixed base station.
Have a free wireless channel that does not interfere with the line channel
Second detecting means for detecting a second fixed base station,
However, the mobile relay station is in the second fixed base station.
Using a free radio channel, the first fixed base station
Communication between the mobile station existing in the area and the second fixed base station
It is characterized by relaying communication .

A mobile communication system according to a third aspect of the present invention is a mobile communication system in which a plurality of fixed base stations connected to a network and mobile stations existing in an area of the plurality of fixed base stations communicate with each other via a radio channel. , The plurality of solid
Of the fixed base stations, the first fixed base station in which congestion has occurred
Of the plurality of fixed base stations,
Of which, it is possible to communicate with mobile relay stations
And in the area of the first fixed base station
Use free radio channels to increase the number of radio channels
Second detecting means for detecting a second fixed base station,
And the mobile relay station is the second fixed base station.
The frequency band of the empty radio channel is set to the first fixed value.
Frequency that does not interfere with the radio channel used by the base station
Convert to band and use the converted free wireless channel
And a mobile station existing in the area of the first fixed base station.
And relaying communication with the second fixed base station .

[0012] The mobile communication system according to claim 4, wherein, in the as described in any one of claims 1 to 3, wherein the
The detection means 1 is the position of each mobile unit and the error of each fixed base station.
Of the congestion in each fixed base station based on the position of
Occurrence / non-occurrence is predicted, and congestion of each fixed base station
It is characterized in that the first fixed base station whose occurrence is predicted is detected .

A mobile communication system according to claim 5 is
Item 1. The control device according to Item 1, wherein the control device is the mobile unit.
Control the altitude of the ground station to change the area of the mobile base station.
It is characterized by making it.

According to another aspect of the mobile communication system of the present invention,
Item 2 or 3, wherein the mobile relay station is
It is characterized by moving in the air. Claim 7
The mobile communication system according to claim 6,
During the movement based on the detection result of the first detecting means
A control device for controlling the movement of the relay station;
Controls the altitude of the mobile relay station to
It is characterized by changing the area. Claim 8
The mobile communication system described above is also the mobile communication system according to claim 2 or 3.
Based on the detection result by the first detecting means.
And a control device for controlling the movement of the mobile relay station.
It is characterized by that.

A mobile communication system according to a ninth aspect is the mobile communication system according to the first or the eighth aspect , further comprising an operating element, and a control console for controlling the control device according to an operation content of the operating element. the control device is characterized by controlling the movement of the mobile base station or the mobile relay station in accordance with the operation contents of said control console. A mobile communication system according to claim 10 is the mobile communication system according to claim 2 or 3 ,
The mobile relay station is portable.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. A. First Embodiment Configuration of First Embodiment FIG. 1 is a block diagram showing a partial configuration of a mobile communication system according to a first embodiment of the present invention. The mobile communication system shown in this figure is a Japanese automobile / mobile phone. By using two frequency bands of 800 MHz band and 1.5 GHz band used in a telephone, dynamic channel addition by a levitation base station (mobile base station) described later is easily realized.

In FIG. 1, reference numeral 3 denotes a fixed base station arranged according to the overall carrier arrangement plan, which is 800 MH.
A z-band carrier is assigned. Although a plurality of fixed base stations are provided, only the fixed base station 3 is illustrated here. Each fixed base station has an antenna and a transmitter / receiver used for other than normal communication, and outputs a signal unique to each fixed base station for position registration of the levitation base station from the control device 10 (described later). Send based on instructions. Reference numeral 30 denotes an area (zone or sector) covered by the fixed base station 3, and in this area 30, a mobile device 31 such as a mobile phone 31 is provided.
~ 36 exist.

Reference numeral 8 denotes a mobile communication exchange in which a plurality of fixed base stations including the fixed base station 3 are wire-connected, and is generally used for control of each fixed base station, exchange of communication lines, call channel allocation processing, handover processing, etc. In addition to its function as a traditional mobile communication switch, it also exchanges communication lines via a levitation base station and sends and receives call connection signals with the levitation base station.
It has the ability to control communications over channels that are dynamically added by the levitation base station.

The mobile communication exchange 8 is provided with a movable antenna and a transceiver for establishing a radio line equivalent to a communication line between the fixed base station and the mobile communication exchange, between the floating base station. The communication via the fixed base station and the communication via the levitation base station can be treated equally.
Although a plurality of mobile communication exchanges are provided, only the mobile communication exchange 8 is illustrated here.

Reference numeral 10 is a control device to which a plurality of mobile communication exchanges are connected by wire, and 11 is a control console of the control device 10, which is provided with an operator for operating the control device 10. 60
Is a home memory such as an electronic disk for recording the location of each mobile unit.
Read and write to 0. The home memory 60 includes a mobile station position table that stores the current position of each mobile station, a fixed station state table that stores the state of each fixed base station, and a levitation station state table that stores the state of each levitation base station. It is stored.

Here, a configuration example of each table is shown in FIG.
~ Fig. 2 (c). As shown in FIG. 2A, the mobile station position table includes a field of a mobile station number unique to each mobile station and a field of an area number (location area) in which the mobile station is located. In addition, FIG.
As shown in, the fixed station status table includes a field of a fixed base station number unique to each fixed base station, a field of the fixed base station (“congested” or “normal”), and a field of the fixed base station. Position (latitude, longitude) field,
Area number covered by fixed base station (cover area)
And the field of.

Further, as shown in FIG. 2C, in the levitation station state table, the field of the levitation body base station number unique to each levitation body base station and the current position (latitude, longitude) of the levitation body base station. , Altitude) field, position (previous position) before a predetermined time, and time (vacant time) field since the last time the channel set by the floating base station was used. A field for the target position (latitude, longitude, altitude), a field for the moving direction of the levitating base station, a field for moving speed, and a field for the number of the area covered by the levitating base station (cover area) are provided. There is. Depending on the altitude of the levitation base station, the cover area may have a plurality of values.

Further, the control device 10 is provided with an antenna and a transceiver for establishing a dedicated channel with the levitation base station, and a signal from the mobile communication exchange 8 or a signal from the control console 11 is used. It has a function of controlling each levitation base station based on the contents of each table in the home memory 60 and a signal supplied from the levitation base station via a dedicated channel.

The levitation base station 1 is, for example, a base station mounted on an airship, a helicopter, or the like, and as shown in FIG. 3, a levitation function including a levitation propulsion device and a control device. It is composed of a unit 110, a base station function unit 120 that realizes a function as a base station, and a control unit 130 that controls both. The base station function unit 120 has an antenna 103 for establishing a multiple channel with a mobile communication exchange, and a communication channel, an access channel, and a broadcast channel for setting a 1.5 GHz band in a lower area. The antenna 104 is connected. In addition,
When a 1.5 GHz band carrier is assigned to each fixed base station, an antenna for setting a call channel, an access channel, and a broadcast channel in the 800 MHz band is used as the antenna 104.

Further, the control unit 130 has an antenna 101 for establishing a dedicated channel with the control device 10.
Is connected to the GPS antenna 102 that receives a signal unique to each fixed base station when registering its own position, and the control unit 130 controls each unit based on a signal from the control device 10. At the time of registering its own position, the control unit 130 receives signals specific to each fixed base station transmitted from each fixed base station according to an instruction from the control device 10, and transmits the three highest level signals to the control device 10. To do.

Communication Example in First Embodiment (1) Normal Operation First, a normal operation that is performed independently of a call and an incoming call will be described. The control device 10 updates the “current position” of each levitation base station in the levitation station state table (see FIG. 2C) to the latest value at predetermined time intervals. Specifically, as shown in FIG. 4, first, the control device 10 reads out the current position of the levitation body base station to be updated from the levitation station state table, and detects a plurality of (for example, four) closest to the current position. A signal unique to each fixed base station is transmitted from the fixed base station. Then, the three highest level signals received by the floating base station to be updated are transmitted to the control device 10, and the current position is determined based on the levels of the three signals and the position of the fixed base station that transmitted each signal. Are seeking. The updated old position is recorded as the previous position and held until the next update. Further, the location registration of each mobile station is performed by each mobile communication exchange and each fixed base station at a predetermined time interval, and the position of each area covered by each fixed base station is shown in the mobile station location table (see FIG. registered in a)).

Further, as shown in FIG. 5, the mobile telecommunication exchange 8 checks whether or not there is a congested area under its control (step SA1), and if it exists, the congested area is checked. The status of the corresponding fixed base station is "congested"
(Steps SA2 and SA3). Specifically, in the fixed station state table (see FIG. 2B) in the home memory 60, the state of the fixed base station corresponding to the congestion area is set to "congested".

On the other hand, as shown in FIG. 6, the control device 10 refers to the fixed station state table to determine whether or not there is a congestion area (step SB1). A buoyant base station to be dispatched to the congested area is selected (step SB2). Specifically, the levitation base station that can move to the area 30 is searched from the levitation station state table, and the area 30 of the hit levitation base stations is searched.
The best float base station to move to.

It is to be noted that the "movable" is judged to be a floating base where the "free time" during which communication via the channel set by itself is not performed exceeds the preset congestion release time. It is a station. Further, the congestion release time is a time such that the probability that an area (fixed base station) that has left the congestion state will be in the congestion state again within a predetermined time is sufficiently low. If the congestion state is released before selecting the buoyant base station that can be dispatched, the buoyant base station dispatch is suspended.

Further, the selection of the levitation body base station most suitable for the movement to the area 30 is performed by extracting the one having the shortest movement distance to the target position (latitude, longitude, height) above the area 30. To be done. Here, it is assumed that there is no obstacle on the moving route of the levitation base station, and the shortest straight line between the current position (latitude, longitude, height) of the levitation base station and the target position is obtained, and this is calculated. The distance traveled from the station to the area 30 is used.

The target position is obtained by adding height information to the position (latitude, longitude) of the fixed base station 3 covering the congestion area. The height information added here can change the size of the area that can be covered by one levitation base station, but here, the height information that can cover the area that substantially matches the congestion area is added. Seeking the target position. A plurality of floating base stations may be dispatched to the same area, but in that case, it is necessary to set each target position so that each floating base station does not collide.

When the optimum levitation base station (herein, levitation base station 1) is selected, the control device 10 determines the levitation base station 1 based on the current position and the target position of the levitation base station 1. The moving direction and moving speed are obtained, and both are sent to the levitation base station 1 via a dedicated channel (step SB3 in FIG. 6). The moving speed required here is set to be the fastest under various conditions such as the capability of the propulsion system of the floating base station and flight safety.

Upon receiving the moving direction and the moving speed, the levitation body base station 1 controls / drives each part of the propulsion system by the levitation body function unit 110, and starts its own movement at the moving speed in the moving direction. To do. The control device 10 obtains the moving direction and the moving speed at predetermined time intervals until the levitation base station 1 reaches the target position, and sends them to the levitation base station 1 via a dedicated channel. Note that the control device 10 obtains the actual moving speed based on the current position, the previous position, and the update time interval of the current position, and considers the difference between the moving speed and the set moving speed to determine the new moving speed. The error is reduced as determined.

When the levitation base station 1 is within a predetermined error range from the target position, the control device 10 instructs the levitation base station 1 to stop. As a result, the floating base station 1
Stops near the target position. It should be noted that the determination / transmission of the moving direction and the moving speed, and the stop instruction may be performed according to the operation of the control console 11. For example, when dispatching a levitation base station to an area where traffic is expected to concentrate due to holding a planned event in advance,
Manual operation by the control console 11 is required when the base station of the float radio device is retracted to a predetermined position during refueling or when the weather conditions are poor.

Next, the control device 10 sends a transmission start signal to the levitation base station 1 via a dedicated channel so as to start the activity as a radio base station, and the base station function unit 120.
The float base station 1 is caused to function as a base station (step SB4 in FIG. 6). As a result, a plurality of channels (a plurality of communication channels, a broadcast channel, and an access channel) are set in the area 30 in the frequency band of 1.5 GHz, and a fixed base station is provided between the levitation base station 1 and the mobile communication exchange 8. A multi-channel equivalent to a signal line between the mobile communication switchboard 3 and the mobile communication exchange 8 is set. At the time of setting the multiple channels, optimum antenna orientation and transmission power control are performed between the levitation base station 1 and the mobile communication exchange 8. The floating base station 1 that has received the transmission start signal starts measuring the free time. The idle time is the elapsed time from the time when the speech channel set by the floating base station 1 was last used, and the measured value is the control device 1 at predetermined time intervals.
0 and recorded in the levitation station status table.

(2) Calling operation during congestion Next, the mobile station 31 calls another mobile station under the condition that the levitation base station 1 is dispatched to the congested area 30. The operation of starting communication (call) will be described. First, the mobile device 31 uses two broadcast channels (8
Fixed base station 3 via 00 MHz band and 1.5 GHz band)
Also, it receives information on the floating base station 1 and information on two access channels used for transmitting the calling signal, and transmits the calling signal to the fixed base station 3 and the floating base station 1 via both access channels. . These call signals are sent to the mobile communication switch 8 via the fixed base station 3 or the floating base station 1.
Is supplied to.

As shown in FIG. 7, the mobile telecommunication exchange 8 basically tries to communicate via a fixed base station.
Since there is no available communication channel in the fixed base station 3, a levitation base station that covers the area 30 is searched (steps SC1 to SC3), and a connection operation is started via the levitation base station 1 found. (Step SC4). Specifically, from the levitation base station 1 to the mobile station 31 via the access channel, the communication channel (1.5 GHz) to be used.
Band) is notified, and the connection operation using the call channel is started. After that, communication can be performed via a call channel in the 1.5 GHz band.

When the area of the calling mobile station is not congested, normal connection processing is performed, the position of the calling mobile station exists in the congestion area, and the floating base station If not dispatched, the connection process is not performed, and the mobile device is notified that congestion is occurring.

(3) Operation during incoming call during congestion Next, under the condition that the levitation base station 1 is dispatched to the congested area 30, a call is made to the mobile device 32 for communication (call). The operation to start will be described. Upon receipt of the incoming call request signal, the mobile telecommunication exchange 8 refers to the home memory 60 to identify the area to which the incoming call destination mobile station (here, the mobile station 32) belongs (steps SC1, SC5), and the area 30 Attempt to communicate via the fixed base station 3 that covers the.

However, since there is no available communication channel in the fixed base station 3, a buoyant base station that covers the area 30 is searched (steps SC6 and SC).
7) The connection is made via the buoyancy base station 1 found (step SC8). Specifically, the floating base station 1 notifies the mobile device 32 of the call channel (1.5 GHz band) to be used via the call channel, and the connection using the call channel is performed. After that, the mobile device 32 is called through the call channel (step SC9), and 1.5G
Communication is performed via a call channel in the Hz band.

If the area to which the destination mobile station belongs is not congested, normal connection processing is performed, the location of the destination mobile station is within the congestion area, and the floating If the base station is not dispatched, the connection process is not performed and the calling side is notified that congestion is occurring.

B. Second Embodiment Configuration of Second Embodiment FIG. 8 is a block diagram showing a partial configuration of a mobile communication system according to a second embodiment of the present invention, and portions common to FIG. 1 are assigned the same reference numerals. There is. The mobile communication system shown in FIG. 8 uses two frequency bands, the 800 MHz band and the 1.5 GHz band, as in the first embodiment.
The mobile communication system shown in this figure is greatly different from that of the first embodiment in that a floating body relay station (mobile relay station), which will be described later, is used instead of the floating body base station to enable effective use of channels. That is the point.

In FIG. 8, 3a to 5a are fixed base stations arranged according to the overall carrier arrangement plan, and 8
Carriers in the 00 MHz band (or 1.5 GHz band) are assigned. The fixed base stations 3a to 5a have the same function as that of the fixed base station 3 (see FIG. 1), and also have a function of setting a speech channel assigned to itself to the floating relay station. This function is realized by a movable antenna that changes its direction in response to an instruction from the mobile communication exchange, a transceiver, and the like.

The mobile communication exchanges 9a and 9b each have a function of controlling communication via an alternative base station (described later) in addition to a function as a general mobile communication exchange. The fixed base station 3 is provided in the mobile communication switch 9a.
The mobile communication switch 9b is connected to a fixed base station 5a and the like. Floating body relay stations 2a and 2b relay the communication channel set with the fixed base station to the outside of the area covered by the fixed base station.

The structure of the floating base stations 2a and 2b will be described with reference to FIG. In FIG. 9, FIG.
The same parts as those in FIG. In FIG. 9, 121 is a floating body relay station 2a, 2b.
Is a relay station function unit that functions as a relay station, and includes a transceiver and an amplifier. This relay station functional unit 12
1 has a function of radiating a channel received via the antenna 201 for the fixed base station and the antenna 202 for the levitation body relay station to the lower side of the levitation body relay stations 2a and 2b via the antenna 104. Further, 131 is the control device 10a.
A control unit that controls the levitation body function unit 110 and the relay station function unit 121 according to an instruction from (described later), and a function different from the control unit 130 (see FIG. 2) will be described later.

Reference numeral 61 denotes a home memory, which is read and written by the mobile communication exchanges 9a and 9b and the control device 10a.
Similar to the home memory 60, the home memory 61 stores a mobile station position table, a fixed station status table, a levitation station status table, and the like. However, the fixed station status table has a structure as shown in FIG. Figure 1
The table configuration shown in 0 differs from the table configuration shown in FIG. 2B in that the fixed base station is assigned to an alternative base station field indicating whether the fixed base station functions as an alternative base station and an area not covered. The point is that an alternative channel field indicating the call channel and an alternative area field to which the alternative channel is assigned are added. In addition,
Differences between the control device 10a and the control device 10 (see FIG. 1) will be described in the following communication example.

Communication Example in the Second Embodiment (1) Normal Operation First, a normal operation that is performed independently of outgoing and incoming calls will be described. Control device 10 in the first embodiment
Similarly, the control device 10a updates the current position of each levitation relay station in the levitation station state table (see FIG. 2C) at predetermined time intervals. In addition, the mobile communication switch 9
Similarly to the mobile communication exchange 8 of the first embodiment, a and 9b check whether or not there is a congested area under the control (step SD1 in FIG. 11), and if there is,
The state of the fixed base station corresponding to the congestion area is set to congestion (steps SD2 and SD3).

On the other hand, as shown in FIG. 12, the control device 10a refers to the fixed station state table to determine whether or not there is a congestion area (step SE1). The mode is set to the congestion mode (step SE2), and the floating body relay station to be dispatched to the congestion area is selected (step SE3). The specific selection process is basically the same as that of the first embodiment.

However, in the present embodiment, relaying via a plurality of levitation body relay stations is also possible, so the content of the levitation body relay station selection processing is the alternative base station selected by the mobile communication exchanges 9a, 9b. The difference from the first embodiment is that it can be changed according to. Therefore, it may be possible to select the alternative base station and then the levitation relay station, but it is essential to dispatch the levitation relay station to the congestion area, and its target position is only the position of the congestion area. Therefore, the levitation relay station is selected here even if the alternative base station is not selected.

When the optimum floating body relay station (here, only the floating body relay station 1 is selected), the control device 10a moves the floating body relay station thereafter, but the processing content (step SE4) is Since it is similar to that of the first embodiment, the description thereof is omitted. When the floating body relay station 2a is stopped near the target position, the control device 10a sends a relay start signal to the floating body relay station 2a via a dedicated channel so that the floating body relay station 2a starts its activity as a wireless relay station. The floating body relay station 2a is caused to function as a relay station by the section 121 (step SE5). At this time, as in the first embodiment, the floating body relay station 2a starts measuring the idle time.

On the other hand, in the mobile communication exchanges 9a and 9b, as shown in FIG. 11, when the processing mode is the congestion mode, an alternative base station that can provide a call channel instead of the congested fixed base station is provided. Search for stations (step SD
4, SD5). It should be noted that the mobile communication exchanges 9a and 9b can detect whether or not there is an empty channel in each fixed base station.

As a result of the above search, when a fixed base station 4a which can be an alternative base station is found, the mobile communication exchanges 9a, 9b are found.
Supplies the fixed base station number "2" and the identification information of the vacant communication channel to the control device 10a. As a result, the control device 10a sets "YES" to the content of the alternative base station field of the fixed base station represented by the fixed base station number, and determines which of the available communication channels to use as the alternative channel. To do.

In the above determination, the alternative channel needs to be a channel that does not cause interference in the congestion area, and it is necessary to avoid the situation in which the alternative base station causes congestion by securing the alternative channel. Here, as shown in FIG. 10, it is assumed that the channel represented by “a” is selected as the alternative channel to be allocated to the area represented by “1”.

Then, the control device 10a supplies the mobile communication exchange 9a with a signal for causing the fixed base station 4a to function as an alternative base station to the fixed base station 3a. As a result, the mobile telecommunication exchange 9a changes the notification content via the notification channel set in the area 30, and disables the free channel represented by "a" of the fixed base station 4a in the area 40. Perform processing (Fig. 11)
Steps SD6 and SD7).

When the fixed base station 4a is used as an alternative base station, a sufficient number of channels cannot be ensured in the area 30, or when the alternative base station exists only in a distant place that cannot be relayed only by the levitation relay station 2a. The controller 10a instructs the levitation body relay stations 2a and 2b to perform the relay via the levitation body relay station 2a and the levitation body relay station 2b. As a result, a relay channel is set by the antennas 202, 202 between the floating body relay station 2a and the floating body relay station 2b. This relay channel is the alternate channel itself.

As shown in FIG. 13, the fixed base station assigned the role of the alternative base station first determines the current position of the levitation relay station used for relaying via the mobile communication exchange 8 as a control device. 10a is queried and acquired (step SF1). Next, the relay antenna is directed to the floating body relay station (step SF2), and a radio wave transmission / reception test is performed (step SF3). If this test result is not good, the orientation of the relay antenna is adjusted until it becomes good (steps SF4 and SF5). This ensures that the alternative channel is relayed to the congestion area. In addition, the fixed base station assigned the role of the alternative base station will thereafter use a channel other than the alternative channel for a call within the area of the own station (own station call) and a call within the alternative area (the alternative call). An alternative channel is assigned to. The local call and the alternative call can be easily discriminated from the call supplier.

(2) Operation during call origination during congestion Next, in the situation where the levitation relay station 2a and the levitation relay station 2b are dispatched to the congested area 30, the mobile station 31
The operation of calling another mobile device and starting communication (call) will be described. First, the mobile device 31 transmits a calling signal to the fixed base station 3a via the access channel in the area 30. This calling signal is supplied to the mobile communication exchange 9a via the fixed base station 3a. Mobile communication switch 9a
Is basically a fixed base station 3a, as shown in FIG.
However, since the fixed base station 3a does not have a vacant communication channel, the levitation relay station and the alternative base station that cover the area 30 are searched (steps SG1 to SG3), and are searched. The connection operation is started via the floating body relay station 2a and the alternative base station (fixed base station) 4a (step SG4). Specifically, the fixed base station 3
The communication channel to be used (the channel represented by the symbol "a") is notified from a to the mobile device 31 via the access channel, and the connection operation using the communication channel is started. After that, communication via the call channel of the call channel becomes possible.

When the area of the calling mobile station is not congested, normal connection processing is performed, the position of the calling mobile station is within the congestion area, and the floating relay station and If any of the alternative base stations is not set, the connection process is not performed, and the mobile device is notified that the congestion is in progress.

(3) Operation at the time of incoming call during congestion Next, the floating body relay stations 2a, 2 are installed in the congested area 30.
The operation of receiving a call to the mobile device 32 and starting communication (call) under the condition that b is dispatched will be described. Upon receipt of the incoming call request signal, the mobile communication exchange 9a identifies the area to which the incoming call destination mobile station (here, the mobile station 32) belongs by referring to the home memory 61 (steps SG1 and SG).
5) Attempt to communicate via the fixed base station 3a that covers the area 30.

However, since there is no available communication channel in the fixed base station 3a, the levitation body relay station and the alternative base station which cover the area 30 are searched (steps SG6 and SG7). Here, it is assumed that the floating body relay stations 2a and 2b and the fixed base station 5a are obtained as a result of the search. Next, the mobile communication switch 9a connects to the mobile device 32 via the mobile communication switch 9b, the searched levitation body relay stations 2a and 2b, and the fixed base station 5a (step SG).
8). Specifically, the fixed base station 3a informs the mobile device 32 of the speech channel to be used (the channel represented by the symbol "b") via the announcement channel, and the connection using the speech channel is performed. After that, the mobile device 32 is called through the call channel (step SG9),
Communication is performed via the call channel.

When the area to which the called-destination mobile unit belongs is not congested, normal connection processing is performed, the position of the called-destination mobile unit exists in the congested area, and the floating unit If either the relay station or the alternative base station is not set, the connection process is not performed and the calling side is notified that congestion is occurring.

C. Third Embodiment FIG. 15 is a block diagram showing a partial configuration of a mobile communication system according to a third embodiment of the present invention, and portions common to FIG. 8 are given the same reference numerals. The mobile communication system shown in FIG. 15 is similar to the first and second embodiments,
Two frequency bands of 800 MHz band and 1.5 GHz band are used. The mobile communication system shown in this figure is greatly different from that of the second embodiment in that the channel set by each fixed base station is in the 800 MHz band (or 1.5 G).
(Hz band) only, and that the system configuration is simplified by using the levitating body relay station 2c that performs frequency conversion.

FIG. 16 is a block diagram showing the structure of the levitation body relay station 2c. The difference between the levitation body relay station 2c shown in this figure and the levitation body relay station shown in FIG. Instead of this, a frequency conversion booster 122 is provided and the antenna 202 is eliminated. The frequency conversion booster 122 receives 80 via the antenna 201.
Signal of 0MHz band (or 1.5GHz band) is 1.5
Converted to GHz band (or 800MHz band) signal,
After being amplified and then output via the antenna 104, the 1.5 GHz band (or 800 MHz band) signal received via the antenna 104 is converted into an 800 MHz band (or 1.5 GHz band) signal, and after amplification, It has a function of outputting through the antenna 201. That is, the frequency conversion booster 122 uses the 800 MHz band (or 1.5 GHz) allocated from the alternative base station.
The alternative channel of the band is the 1.5 GHz band (or 800
It can be converted into a channel of (MHz band) and radiated to the congestion area.

Therefore, the speech channel added to the congestion area is 1.5 GHz band (or 800 MHz band).
, And does not interfere with the channel of 800 MHz band (or 1.5 GHz band) set in the congestion area by the fixed base station without considering the interference in the second embodiment. Therefore, the system configuration can be simplified.

D. 5. Summary As described above, according to the embodiment of the present invention, it is possible to dynamically add a channel to a congestion area, so that it is possible to reduce a communication-disabled state due to congestion.
Further, since the position of the mobile device is registered in units of areas covered by the fixed base station, the occurrence of congestion is predicted based on the position of each mobile device and the position of each area covered by each fixed base station. be able to. Therefore, it is possible to dispatch the levitation base station or levitation relay station before congestion occurs to prevent the occurrence of channel shortage. Furthermore, according to the second and third embodiments, since the channel additionally set in the congestion area is an empty channel, a finite frequency band can be effectively used.

The present invention is not limited to this embodiment. For example, in the second embodiment, the two frequency bands of 800 MHz band and 1.5 GHz band are used, but only one of them may be used. In this case, the mobile device only needs to support one of the frequency bands. Also, 800MHz
Not limited to the band and the 1.5 GHz band, for example, coexistence with PHS (Personal Handy-phone System) of the 1.9 GHz band is also possible. Further, the number of channels to be additionally set and the levitation base station or levitation relay station to be dispatched may be changed according to the degree of congestion.

Further, the optimum floating body base station or floating body relay station to be dispatched may be determined based on not only the moving distance but also the fuel (cost) or time used. Furthermore, by referring to the terrain database and the building database, the “distance” to the target position is calculated, and based on this “distance”, the optimum levitation base station or levitation relay station may be determined. Good. In addition, the mobile base station and the mobile relay station are examples of mounting the base station on an airship such as an airship or a helicopter. However, the base station may be mounted on an automobile or a portable base station may be carried by a human. You may

[0068]

As described above, according to the present invention,
By mobile base station or mobile relay station sets a radio channel which is not interference in the fixed base station, the communication is possible using the radio channel, the mobile base station also
By appropriately moving the mobile relay station , it is possible to reduce the occurrence of the communication disabled state due to the shortage of wireless channels without newly installing a fixed base station . Further , the occurrence / non-occurrence of congestion in each fixed base station is predicted based on the position of each mobile device and the position of the area of each fixed base station, and the mobile base station or the mobile relay station is moved according to the prediction result. It is possible to prevent congestion from occurring .

[Brief description of drawings]

FIG. 1 is a block diagram showing a partial configuration of a mobile communication system according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a data structure in a home memory in each embodiment of the present invention, in which (a) is a mobile station position table, (b) is a fixed station state table, and (c) is a levitation station state table. The data structure is shown.

FIG. 3 is a block diagram showing a configuration of a levitation base station according to the first embodiment of the present invention.

FIG. 4 is a diagram for explaining location registration processing of a levitation base station or levitation mobile station in each embodiment of the present invention.

FIG. 5 is a flowchart showing a part of the operation of the mobile communication exchange according to the first embodiment of the present invention.

FIG. 6 is a flowchart showing the operation of the control device in the first embodiment of the present invention.

FIG. 7 is a flowchart showing an operation at the time of making / receiving a call of the mobile communication exchange according to the first embodiment of the present invention.

FIG. 8 is a block diagram showing a partial configuration of a mobile communication system according to a second embodiment of the present invention.

FIG. 9 is a block diagram showing a configuration of a levitating body relay station according to a second embodiment of the present invention.

FIG. 10 is a diagram showing a data structure of a fixed station status table according to the second embodiment of the present invention.

FIG. 11 is a flowchart showing a part of the operation of the mobile communication exchange according to the second embodiment of the present invention.

FIG. 12 is a flowchart showing an operation of the control device in the second embodiment of the present invention.

FIG. 13 is a flowchart showing a part of the operation of the alternative base station according to the second embodiment of the present invention.

FIG. 14 is a flowchart showing an operation at the time of making / receiving a call of the mobile communication exchange according to the second embodiment of the present invention.

FIG. 15 is a block diagram showing a partial configuration of a mobile communication system according to a third embodiment of the present invention.

FIG. 16 is a block diagram showing a configuration of a levitating body relay station according to a third embodiment of the present invention.

[Explanation of symbols]

1 Float base station, 2a, 2b, 2c Floating body relay station, 3, 3a, 4a, 5a fixed base stations, 8, 9a, 9b mobile communication exchanges, 10, 10a control device, 31-36, 41-43,51 mobile units, 60,61 Home memory.

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04B ^7/ 24-7/26 102 H04Q ^7/ 00-7/38

Claims (10)

(57) [Claims] 1. A mobile communication system in which a plurality of which are connected to the network fixed base station and a mobile station to be located in an area of said plurality of fixed base stations and communicate through a radio channel, said plurality of fixed base stations First of all, congestion is occurring
The first detecting means for detecting a fixed base station, sets the first fixed base station is not a radio channel confused <br/> signal using a radio channel, the first through the radio channel A mobile base station moving in the air, which communicates with a mobile station existing in the area of one fixed base station, and the mobile station based on the detection result by the first detecting means.
A mobile communication system , comprising: a control device that controls movement of a base station . 2. A mobile communication system in which a plurality of fixed base stations connected to a network and a mobile device existing in an area of the plurality of fixed base stations communicate with each other via a radio channel , First of all, congestion is occurring
And a movable mobile relay station among the plurality of fixed base stations.
Communication is possible, and the first fixed
Do not interfere with the radio channel used by the base station
Detecting a second fixed base station having a line channel
2 detecting means, wherein the mobile relay station is free in the second fixed base station.
Using a wireless channel, the first fixed base station
Communication between the mobile station existing in A and the second fixed base station
A mobile communication system characterized by relaying . 3. A mobile communication system in which a plurality of fixed base stations connected to a network and a mobile device existing in an area of the plurality of fixed base stations communicate with each other via a radio channel , First of all, congestion is occurring
First detection means that detect a fixed base station, among the plurality of fixed base station, a movable mobile relay station
Communication is possible, and the first fixed
To increase the number of wireless channels in the base station area
Detects a second fixed base station using a free radio channel
And a second detecting unit that is provided in the mobile station , wherein the mobile relay station is free in the second fixed base station.
The frequency band of the radio channel is set by the first fixed base station.
Change to a frequency band that does not interfere with the wireless channel you are using.
And use the converted free radio channel
The mobile station existing in the area of the first fixed base station and the mobile station
A mobile communication system, which relays communication with two fixed base stations . 4. The position of each mobile unit is determined by the first detecting means.
And each fixed base station based on the location of each fixed base station area
Predict the occurrence / non-occurrence of congestion at the base station,
First fixed base station in which congestion is predicted to occur among fixed base stations
4. A station according to claim 1, wherein the station is detected.
A mobile communication system described therein. 5. The altitude of the mobile base station is controlled by the control device.
Control to the to varying the area of the mobile base station
The mobile communication system according to claim 1, wherein the mobile communication system is a mobile communication system. 6. The mobile communication system according to claim 2, wherein the mobile relay station moves in the air. 7. Based on the detection result by the first detecting means.
Zui comprising a control device for controlling the movement of the pre-Symbol mobile relay station, wherein the control device, wherein, wherein varying the area of the front Symbol mobile relay station by controlling a high degree of pre-Symbol mobile relay station Item 7. The mobile communication system according to item 6 . 8. Based on the detection result by the first detecting means.
The mobile communication system according to claim 2 or 3, characterized in that it comprises a control device for controlling the movement of the pre-Symbol mobile relay station Zui. 9. comprises a operating element, comprising a control console for controlling the control device in accordance with the operation contents of the operator, the control device the mobile base station or in response to said operation contents of said control console The mobile communication system according to claim 1 or 8 , which controls movement of the mobile relay station. 10. The mobile communication system according to claim 2, wherein the mobile relay station is portable.