JPH1066138A - Mobile communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mobile communication system which can prevent a communication disabled state that is caused by temporary congestion from occurring without causing a high cost. SOLUTION: A radio channel which does not generate interference with radio channels is set by a floating body base station or a floating body repeater station within an area where the radio channels of 800MHz band (or 1.5GHz band) are set by a fixed base station, and the number of radio channels in the area is automatically increased. For instance, radio channels which are set by each fixed base station are unified to 800MHz band (or 1.5GHz band), a free radio channel in an area 40 is converted into a radio channel of 1.5GHz band (or 800MHz band) by the portable floating body repeater station 2c and emitted to a congested area 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a mobile communication system.

[0002]

2. Description of the Related Art Conventionally, a telecommunications carrier has provided a radio base station (hereinafter referred to as a “fixed base station”) in a service area in order to provide a communication service using a mobile device such as a mobile phone smoothly and efficiently. In order to optimize the arrangement (zone configuration or sector configuration), detailed investigations and studies are conducted before and after the construction of the mobile communication network.

If the number of channels in a certain area (zone or sector) is insufficient as a result of the investigation and examination, the communication carrier increases the number of channels available in the area (in the area). Fixed base stations have been added to the network) and are working to maintain a sufficient number of channels.

[0004]

However, no matter how intensively researching and examining and optimizing the zone (sector) configuration, it may not be possible to sufficiently cope with the instantaneous mass generation of traffic. For example, when a sudden incident / accident or disaster occurs in a certain area, or a rally of a large number of people occurs, mobile devices concentrate in the area and the fixed base station capacity (number of channels) is temporarily set. May be generated.

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 fluctuate in a short term, it is possible to know in advance the maximum possible traffic volume. However, in a mobile communication network, it is impossible to know in advance the maximum amount of traffic that can occur in each fixed base station due to the fateful feature of mobile communication that "mobile devices can move freely".

[0006] Of course, if the capacity of each fixed base station is made extremely large and it is possible to sufficiently process even when all mobile stations communicate simultaneously, it is possible to cope with traffic concentration due to a sudden event. It is impractical to arrange many fixed base stations in terms of cost. In the first place, how TDMA (Time Division Multiple Access), CD
In order for the technology of MA (Code Division Multiple Access) to advance, it still needs an unrealistically wide frequency band, which is practically impossible.

After all, there is no technology that essentially solves the occurrence of a communication disabled state due to temporary congestion due to the fateful feature of mobile communication that "mobile equipment can move freely". At the time of congestion, the user of the mobile device has to refrain from using the mobile device in the congested area. However, in general, the communication at the time of a sudden event is often urgent, and the situation that the mobile device cannot be used immediately or has to communicate after moving to another area occurs in the public. Without arranging in the queue of the telephone, the convenience of mobile communication that "can be communicated anytime and anywhere" is greatly impaired.

The present invention has been made in view of such a background, and an object of the present invention is to provide a mobile communication system capable of preventing occurrence of a communication disabled state due to temporary congestion without increasing costs. The purpose is.

[0009]

According to a first aspect of the present invention, there is provided a mobile communication system comprising a fixed base station connected to a network and a mobile station existing in an area of the fixed base station. In a mobile communication system that communicates via a wireless channel, the mobile base station includes a movable mobile base station that sets a wireless channel that does not cause interference in the fixed base station and communicates with the mobile device via the wireless channel. Is connected to the network.

A mobile communication system according to a second aspect of the present invention is a mobile communication system in which a plurality of fixed base stations connected to a network and a mobile station located in an area of the plurality of fixed base stations communicate via a radio channel. A mobile relay station that relays a radio channel, which has low traffic at the first fixed base station and does not cause interference at the second fixed base station, to an area of the second fixed base station, Is connected to the network. Mobile communication system.

According to a third aspect of the present invention, there is provided a mobile communication system in which a plurality of fixed base stations connected to a network and a mobile station located in an area of the plurality of fixed base stations communicate via a radio channel. A movable mobile relay station that converts a radio channel with low traffic in the first fixed base station into a radio channel that does not cause interference in the second fixed base station and relays the radio channel to an area of the second fixed base station; A mobile relay station is connected to the network.

A mobile communication system according to a fourth aspect is the mobile communication system according to any one of the first to third aspects, wherein the mobile base station moves in the air. A mobile communication system according to claim 5, further comprising a control device for controlling movement of the mobile base station or the mobile relay station based on a communication state, wherein the control device is configured to control the movement of the mobile base station. The height of the station or the mobile relay station is controlled to change the area of the mobile base station or the mobile relay station.

According to a sixth aspect of the present invention, there is provided a mobile communication system according to any one of the first to third aspects, further comprising a control device for controlling movement of the mobile base station or the mobile relay station based on a communication state. It is characterized by:
The mobile communication system according to the seventh aspect is the fifth or sixth aspect.
Wherein the communication state is the presence or absence of congestion in each fixed base station.

[0014] In a mobile communication system according to an eighth aspect of the present invention, in the mobile communication system according to the seventh aspect, the control device congestion in each fixed base station based on the position of each mobile station and the position of the area of each fixed base station. Is predicted, and the mobile base station or the mobile relay station is moved according to the prediction result.

A mobile communication system according to a ninth aspect of the present invention is the mobile communication system according to the seventh aspect, further comprising: a control console, wherein the control console controls the control device in accordance with the operation content of the control. The apparatus controls the movement of the mobile base station or the mobile relay station according to the operation content of the control console. The mobile communication system according to claim 10,
The mobile base station according to any one of claims 1 to 3, wherein the mobile base station is portable.

[0016]

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 FIG. Using two frequency bands, 800 MHz band and 1.5 GHz band, used in telephones, dynamic channel addition by a floating base station (mobile base station) described later is easily realized.

In FIG. 1, reference numeral 3 denotes a fixed base station arranged according to an overall carrier arrangement plan, and 800 MHz.
A carrier in the z band is allocated. 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 transceiver used for other than normal communication, and transmits a signal unique to each fixed base station for position registration of the floating 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 within this area 30, a mobile device 31 such as a mobile phone is included.
~ 36 are present.

Reference numeral 8 denotes a mobile communication switching system in which a plurality of fixed base stations including the fixed base station 3 are connected by wire. The mobile communication switch 8 controls general fixed base stations, exchanges communication lines, allocates communication channels, and performs handover processing. In addition to the function as a typical mobile communication switch, such as the exchange of communication lines via the levitation base station and the transmission and reception of call connection signals with the levitation base station,
It has a function of controlling communication via a channel dynamically added by the levitating base station.

The mobile communication exchange 8 is provided with a movable antenna, a transceiver and the like 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 denotes a control device to which a plurality of mobile communication exchanges are connected by wire, and reference numeral 11 denotes a control console of the control device 10, which includes an operator for operating the control device 10. 60
Is a home memory such as an electronic disk for recording the location and the like of each mobile device, and the mobile communication exchange 8 and the control device 1
Read and write to 0. The home memory 60 includes a mobile station position table storing the current position of each mobile station, a fixed station state table storing the state of each fixed base station, a floating station state table storing the state of each floating base station, and the like. Is stored.

Here, an example of the configuration of each table is shown in FIG.
2 (c). As shown in FIG. 2A, the mobile station position table is provided with a field of a mobile station number unique to each mobile station and a field of an area number (location area) where the mobile station is located. FIG. 2 (b)
As shown in the table, 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 status (“congested” or “normal”), and a field of the fixed base station. Location (latitude, longitude) fields,
Number of area covered by fixed base station (covered area)
Field is provided.

Further, as shown in FIG. 2 (c), the levitation station status table contains a levitation base station number field unique to each levitation base station and the current position (latitude and longitude) of the levitation base station. , Altitude), a field of a position before a predetermined time (previous position), a field of an elapsed time (vacant time) since the last time a channel set by the levitating base station was used, and a field to be moved. A field of a target position (latitude, longitude, altitude), a field of a moving direction of the levitating base station, a field of a moving speed, and a field of an area number (cover area) covered by the levitating base station are provided. I have. The value of the coverage area may be plural depending on the altitude of the levitating base station.

The control device 10 has an antenna and a transceiver for establishing a dedicated channel with the levitation base station, and receives signals from the mobile communication exchange 8 or signals from the control console 11. 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 has a base station mounted on, for example, an airship or a helicopter. As shown in FIG. 3, the levitation body function includes a levitation propulsion device, a control device, and the like. It comprises a unit 110, a base station function unit 120 for realizing the function as a base station, and a control unit 130 for controlling both. The base station function unit 120 has an antenna 103 for establishing a multiplex channel with the mobile communication switchboard, and a 1.5 GHz band communication channel, access channel, and broadcast channel in a lower area. The antenna 104 is connected. In addition,
When a carrier in the 1.5 GHz band is assigned to each fixed base station, an antenna for setting a communication channel, an access channel, and a broadcast channel in the 800 MHz band is used as antenna 104.

The control unit 130 has an antenna 101 for establishing a dedicated channel with the control device 10.
And a GPS antenna 102 that receives a signal unique to each fixed base station at the time of registration of its own position. Control of each unit by the control unit 130 is performed based on a signal from the control device 10. When the control unit 130 registers its own location, it receives signals specific to each fixed base station transmitted from each fixed base station in accordance with an instruction from the control device 10 and transmits the three highest-level signals to the control device 10. I do.

Example of Communication in First Embodiment (1) Normal Operation First, a normal operation performed irrespective of an outgoing 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 status table (see FIG. 2C) to the latest value at predetermined time intervals. Specifically, as shown in FIG. 4, first, control device 10 reads the current position of the levitating base station to be updated from the levitating station state table, and sets 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 control unit 10 transmits the three highest-level signals received by the levitation base station to be updated to the control device 10, and determines the current position based on the levels of the three signals and the position of the fixed base station that transmitted each signal. Seeking. The updated old position is recorded as the previous position and held until the next update. The location registration of each mobile station is performed at predetermined time intervals by each mobile communication exchange and each fixed base station, and the location of each area covered by each fixed base station is stored in a mobile station location table (FIG. 2 ( a) is registered.

As shown in FIG. 5, the mobile communication exchange 8 checks whether or not there is a congested area under its control (step SA1). 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 status table to determine whether or not a congestion area exists (step SB1). A levitation base station to be dispatched to the congestion area is selected (step SB2). Specifically, a levitation base station that can move to the area 30 is searched from the levitation station status table, and among the hitting levitation base stations, the area 30 is searched.
Select the most suitable levitation base station for moving to.

It is to be noted that "movable" is determined because a "free time" during which communication via a channel set by itself is not performed exceeds a preset congestion release time. Bureau. In addition, the congestion release time is a time during which the probability that an area (fixed base station) that has exited from the congestion state will re-enter the congestion state within a predetermined time is sufficiently low. If the congestion state is released before selecting a dispatchable levitating base station, dispatch of the levitating base station is stopped.

The selection of the levitating base station which is most suitable for the movement to the area 30 is performed by extracting the shortest moving distance to the target position (latitude, longitude, height) above the area 30. Is done. Here, it is assumed that there are no obstacles on the moving path of the levitating base station, and the shortest linear distance between the current position (latitude, longitude, height) of the levitating base station and the target position is obtained, and this is calculated. It is the moving distance from the station to the area 30.

The target position can be obtained by adding height information to the position (latitude, longitude) of the fixed base station 3 covering the congested area. According to the height information added here, the area of the area that can be covered by one levitating base station can be changed. However, here, height information that can cover an area substantially matching the congestion area is added. To find the target position. Note that a plurality of levitating base stations may be dispatched to the same area, but in that case, it is necessary to set each target position so that the levitating base stations do not collide.

When an optimal levitation base station (here, levitation base station 1) is selected, control device 10 controls levitation base station 1 based on the current position of levitation base station 1 and the target position. The moving direction and the moving speed are obtained, and both are transmitted to the levitation base station 1 via the 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 levitation base station and flight safety.

The levitation base station 1 having received the moving direction and the moving speed controls and 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. I 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. 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 calculates a new moving speed in consideration of a difference between the moving speed and the set moving speed. The error is reduced as calculated.

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. Thereby, the levitation base station 1
Stops near the target position. The determination and transmission of the moving direction and the moving speed, and the stop instruction may be performed in response to the operation of the control console 11. For example, when dispatching a levitation base station to an area where traffic is expected to be concentrated due to holding a planned event in advance,
Manual operation by the control console 11 is required when refueling or when the levitation body radio base station is evacuated to a predetermined position when weather conditions are poor.

Next, the control device 10 sends a transmission start signal to the levitating base station 1 via a dedicated channel so as to start the activity as a radio base station.
Thus, the levitation 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 1.5 GHz frequency band in the area 30, and a fixed base station is provided between the levitation base station 1 and the mobile communication exchange 8. A multiplex channel equivalent to a signal line between the mobile communication exchange 3 and the mobile communication exchange 8 is set. At the time of setting the multiplex channel, the optimal antenna orientation and transmission power are controlled between the levitation base station 1 and the mobile communication switch 8. The levitation base station 1 that has received the transmission start signal starts measuring the idle time. The idle time is the elapsed time since the last time the communication channel set by the levitating base station 1 was used, and the measured value is measured at predetermined time intervals by the controller 1.
0 and recorded in the levitating station status table.

(2) Operation at the time of calling during congestion Next, under the condition that the levitation base station 1 is dispatched to the congested area 30, the mobile unit 31 makes a call to another mobile unit. The operation of starting communication (call) will be described. First, the mobile device 31 transmits two broadcast channels (8
00 MHz band and 1.5 GHz band).
And the information of the floating base station 1 and the information of the two access channels used for transmitting the calling signal, etc., and transmit the calling signal to the fixed base station 3 and the floating base station 1 via both access channels. . These call signals are transmitted to the mobile communication exchange 8 via the fixed base station 3 or the floating base station 1.
Supplied to

As shown in FIG. 7, the mobile communication exchange 8 basically tries to communicate via a fixed base station.
Since there is no vacant communication channel in the fixed base station 3, a search is made for a floating base station that covers the area 30 (steps SC1 to SC3), and a connection operation is started via the searched floating base station 1. (Step SC4). Specifically, a communication channel (1.5 GHz) to be used is transmitted from the floating base station 1 to the mobile station 31 via the access channel.
Is notified, and a connection operation using the communication channel is started. Thereafter, communication via a 1.5 GHz band communication channel becomes possible.

If the area of the calling mobile station is not congested, a normal connection process is performed, the position of the calling mobile station is located within the congested area, and the levitation base station is not connected. If not dispatched, the connection processing is not performed, and the mobile device is notified that congestion is occurring.

(3) Operation at the time of incoming call during congestion Next, under the condition that the levitation base station 1 is dispatched to the congested area 30, the mobile unit 32 receives a call and performs communication (call). The operation to be started will be described. Upon receiving the call request signal, the mobile communication exchange 8 specifies the area to which the called mobile station (here, the mobile station 32) belongs by referring to the home memory 60 (steps SC1 and SC5), and the area 30 To communicate via the fixed base station 3 which covers.

However, since there is no vacant communication channel in the fixed base station 3, a search is made for a floating base station covering the area 30 (steps SC6 and SC).
7) Connect via the found levitated base station 1 (step SC8). Specifically, a communication channel (1.5 GHz band) to be used is notified from the levitating base station 1 to the mobile device 32 via the notification channel, and connection using the communication channel is performed. Thereafter, the mobile station 32 is called via the communication channel (step SC9), and the 1.5G
Communication via a communication channel in the Hz band is performed.

When the area to which the called mobile station belongs is not congested, normal connection processing is performed, and the position of the called mobile station exists in the congested area and the floating body If the base station has not been dispatched, the connection processing is not performed, and the calling side is notified of the congestion.

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. Portions common to FIG. 1 are denoted by the same reference numerals. I have. The mobile communication system shown in FIG. 8 uses two frequency bands, 800 MHz band and 1.5 GHz band, as in the first embodiment.
The major difference between the mobile communication system shown in this figure and that of the first embodiment is that the use of a floating relay station (mobile relay station) described later instead of the floating base station enables effective use of channels. It is a point.

In FIG. 8, reference numerals 3a to 5a denote fixed base stations arranged according to the overall carrier allocation plan.
A carrier of the 00 MHz band (or 1.5 GHz band) is allocated. Each of the fixed base stations 3a to 5a has the same function as the fixed base station 3 (see FIG. 1), and also has a function of setting a communication channel assigned to itself to the floating body relay station. This function is realized by a movable antenna, a transceiver, and the like, which change the direction according to an instruction from the mobile communication exchange.

Reference numerals 9a and 9b denote mobile communication exchanges, respectively, which have a function of controlling communication via an alternative base station (described later) in addition to a function as a general mobile communication exchange. Note that the mobile communication exchange 9a has a fixed base station 3
The fixed base station 5a is connected to the mobile communication exchange 9b. Reference numerals 2a and 2b denote floating body relay stations, which relay a communication channel set with the fixed base station to outside the area covered by the fixed base station.

Here, the configuration of the levitation base stations 2a and 2b will be described with reference to FIG. In FIG. 9, FIG.
The same reference numerals are given to the same parts as those described above, and the description thereof will be omitted. In FIG. 9, reference numeral 121 denotes a floating body relay station 2a, 2b.
Is a relay station function unit that functions as a relay station, and includes a transceiver, an amplifier, and the like. This relay station function unit 12
Reference numeral 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 relay station to below the levitation relay stations 2a and 2b via the antenna 104. Also, 131 is the control device 10a
The control unit controls the levitation body function unit 110 and the relay station function unit 121 in accordance with an instruction from the control unit 130 (described later). Functions different from those of the control unit 130 (see FIG. 2) will be described later.

A home memory 61 is read and written by the mobile communication exchanges 9a and 9b and the control device 10a.
The home memory 61 stores a mobile station position table, a fixed station state table, a floating station state table, and the like, like the home memory 60. However, the fixed station status table has a configuration as shown in FIG. FIG.
0 is different from the table configuration shown in FIG. 2B in that an alternative base station field indicating whether the fixed base station functions as an alternative base station and an area not covered are allocated. The difference is that an alternative channel field indicating a communication channel and an alternative area field to which an 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 examples.

Example of Communication in Second Embodiment (1) Normal Operation First, a normal operation performed irrespective of an outgoing call and an incoming call will be described. Control device 10 in the first embodiment
Similarly to the above, the control device 10a updates the current position of each levitating body relay station in the levitating station status table (see FIG. 2C) at predetermined time intervals. In addition, the mobile communication exchange 9
Steps a and 9b check whether or not there is a congested area under the control (step SD1 in FIG. 11), similarly to the mobile communication exchange 8 of the first embodiment.
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 status table to determine whether or not there is a congestion area (step SE1). The mode is set to the congestion mode (step SE2), and a floating relay station to be dispatched to the congestion area is selected (step SE3). The specific selection processing is basically the same as in the first embodiment.

However, in this embodiment, since relaying via a plurality of floating relay stations is possible, the content of the selection processing of the floating relay station is determined by the alternative base station selected by the mobile communication exchanges 9a and 9b. This is different from the first embodiment in that it can be changed according to. Therefore, the alternative base station may be selected before selecting the levitation relay station. However, dispatch of the levitation relay station to the congestion area is essential, and the target position is only the position of the congestion area. In this case, a floating relay station is selected even if an alternative base station is not selected.

When the most suitable floating body relay station (here, only the floating body relay station 1 is selected) is selected, the control device 10a thereafter moves the floating body relay station. Since it is the same as the first embodiment, the description is omitted. When the levitation relay station 2a is stopped near the target position, the control device 10a sends a relay start signal to the levitation relay station 2a via a dedicated channel so as to start the activity as a wireless relay station. The floating relay station 2a is made to function as a relay station by the unit 121 (step SE5). At this time, as in the first embodiment, the levitating 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 capable of providing a communication channel instead of a congested fixed base station. Search for a station (step SD
4, SD5). Note that whether or not there is an empty channel in each fixed base station can be detected by the mobile communication exchanges 9a and 9b.

As a result of the search, when a fixed base station 4a that can be an alternative base station is found, mobile communication exchanges 9a and 9b
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 the content of the alternative base station field of the fixed base station represented by the fixed base station number to "YES", and determines which of the available communication channels is to be used as the alternative channel. I do.

In the above decision, 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 where congestion occurs in the alternative base station by securing the alternative channel. Here, as shown in FIG. 10, it is assumed that the channel represented by “a” is selected as an 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 a substitute base station for the fixed base station 3a. As a result, the mobile communication exchange 9a changes the broadcast content via the broadcast 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, etc. (FIG. 11
Steps SD6 and SD7).

In the case where a sufficient number of channels cannot be secured in the area 30 simply by using the fixed base station 4a as an alternative base station, or in the case where the alternative base station exists only in a distant place where relaying is not possible only with the floating relay station 2a. The controller 10a instructs the levitation body relay stations 2a and 2b to perform relay via the levitation body relay station 2a and the levitation body relay station 2b. As a result, a relay channel is set between the levitating body relay station 2a and the levitating body relay station 2b by the antennas 202 and 202. This relay channel is the substitute channel itself.

As shown in FIG. 13, the fixed base station to which the role of the substitute base station is assigned first determines the current position of the floating relay station to be used for relay via the mobile communication exchange 8 through the control unit. Inquire to 10a and acquire it (step SF1). Next, the relay antenna is directed to the levitating body relay station (step SF2), and a radio wave transmission / reception test is performed (step SF3). If the test result is not good, the direction of the relay antenna is adjusted until it becomes good (steps SF4 and SF5). This ensures that the alternate channel is relayed to the congestion area. The fixed base station to which the role of the substitute base station has been assigned will thereafter use a channel other than the substitute channel for a call in the area of the own station (own station call) and a call in the substitute area (substitute call). Is assigned an alternative channel. The local station call and the substitute call can be easily distinguished from the source of the call.

(2) Operation at the time of calling during congestion Next, under the condition that the floating body relay station 2a and the floating body relay station 2b are dispatched to the congested area 30, the mobile station 31
A description will be given of an operation in which a call is made to another mobile device to start communication (call). First, the mobile station 31 transmits a call signal to the fixed base station 3a via an access channel in the area 30. This call signal is supplied to the mobile communication exchange 9a via the fixed base station 3a. Mobile communication exchange 9a
Is basically a fixed base station 3a as shown in FIG.
However, since there is no vacant communication channel in the fixed base station 3a, a search is made for a floating relay station and an alternative base station that cover the area 30 (steps SG1 to SG3). 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 the mobile station 31 via the access channel to the mobile device 31, and the connection operation using the communication channel is started. Thereafter, communication via the communication channel of the communication 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 located within the congested area, and the levitation body relay station and If any of the alternative base stations has not been set, the connection processing is not performed, and the mobile device is notified that congestion is occurring.

(3) Operation at the time of incoming call during congestion Next, the floating relay stations 2a, 2
An operation of starting a communication (call) by receiving a call to the mobile device 32 in a situation where “b” is dispatched will be described. Upon receiving the incoming call request signal, the mobile communication exchange 9a refers to the home memory 61 to specify the area to which the called mobile station (here, the mobile station 32) belongs (steps SG1 and SG1).
5) Attempt to communicate via the fixed base station 3a covering the area 30.

However, since there is no free communication channel in the fixed base station 3a, a search is made for a floating relay station and an alternative base station that cover the area 30 (steps SG6 and SG7). Here, as a result of the search, it is assumed that the floating relay stations 2a and 2b and the fixed base station 5a are obtained. Next, the mobile communication switch 9a makes a connection to the mobile device 32 via the mobile communication switch 9b, the found floating relay stations 2a and 2b, and the fixed base station 5a (step SG).
8). Specifically, the fixed base station 3a notifies the mobile device 32 via the broadcast channel of the communication channel to be used (the channel represented by the symbol “b”), and the connection using the communication channel is performed. Thereafter, the mobile station 32 is called via the communication channel (step SG9),
Communication via the communication channel is performed.

If the area to which the called mobile unit belongs is not congested, normal connection processing is performed, and the position of the called mobile unit exists in the congestion area and the floating body If any one of the relay station and the alternative base station has not been set, the connection process is not performed, and the calling side is notified of the congestion.

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 denoted by the same reference numerals. The mobile communication system shown in FIG. 15 is similar to the first and second embodiments,
Two frequency bands, 800 MHz band and 1.5 GHz band, are used. The mobile communication system shown in this figure is significantly different from that of the second embodiment in that the channel set by each fixed base station is in the 800 MHz band (or 1.5G band).
(Hz band) only, and the system configuration is simplified by using the floating body relay station 2c that performs frequency conversion.

FIG. 16 is a block diagram showing the structure of the levitating body relay station 2c. The difference between the levitating body relay station 2c shown in this figure and the levitating body relay station shown in FIG. In that a frequency conversion booster 122 is provided in place of the antenna 202 and the antenna 202 is eliminated. The frequency conversion booster 122 receives the 80
0 MHz band (or 1.5 GHz band) signal
Convert to a signal in the GHz band (or 800 MHz band)
After the amplification, the signal is output via the antenna 104, and 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. It has a function of outputting via an antenna 201. That is, the frequency conversion booster 122 uses the 800 MHz band (or 1.5 GHz) allocated from the alternative base station.
Band) is replaced with a 1.5 GHz band (or 800 GHz band).
(MHz band) and radiate to a congested area.

Therefore, the communication channel added to the congestion area is 1.5 GHz band (or 800 MHz band).
The channel does not interfere with the 800 MHz band (or 1.5 GHz band) channel set in the congestion area by the fixed base station even if the interference in the second embodiment is not considered. Therefore, the system configuration can be simplified.

D. Conclusion 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 also possible to dispatch a levitating base station or a levitating relay station before congestion occurs, thereby preventing shortage of channels. Furthermore, according to the second and third embodiments, since the channel to be 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 the embodiment. For example, in the second embodiment, a configuration is used in which two frequency bands of 800 MHz band and 1.5 GHz band are used, but a configuration in which only one of them is used may be used. In this case, the mobile station needs to support only one of the frequency bands. 800 MHz
In addition to the PHS (Personal Handy-phone System) in the 1.9 GHz band, it is possible to coexist with the PHS (Personal Handy-phone System). Further, the number of additionally set channels and the number of levitation base stations or levitation relay stations to be dispatched may be varied according to the degree of congestion.

The most suitable levitation base station or levitation relay station to be dispatched may be determined based on not only the moving distance but also the fuel (cost) and time used. Furthermore, by referring to the terrain database and the building database, the `` distance '' to the target position is determined, and the most suitable levitation base station or levitation relay station to be dispatched based on the `` distance '' may be determined. Good. Further, the example in which the mobile base station and the mobile relay station are mounted on a flying object such as an airship or a helicopter has been described. However, the mobile base station and the mobile relay station may be mounted on an automobile, or a human may carry a portable base station. It may be.

[0068]

As described above, according to the present invention,
Since the mobile base station or the mobile relay station sets a radio channel that does not cause interference in the fixed base station, communication using this radio channel becomes possible. The occurrence of a communication disabled state due to a shortage of a wireless channel can be reduced without installing a wireless channel. Further, the control device predicts the occurrence / non-occurrence of congestion in each fixed base station based on the position of each mobile station and the position of the area of each fixed base station, and moves the mobile base station or mobile relay station according to the prediction result. Therefore, the occurrence of congestion can be prevented beforehand (claim 7).

[Brief description of the 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, wherein (a) is a mobile station position table, (b) is a fixed station state table, and (c) is a levitated station state table. 2 shows a data structure.

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

FIG. 4 is a diagram for explaining a position registration process of a levitating base station or a levitating 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 illustrating an operation of the control device according to the first embodiment of the present invention.

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

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 illustrating 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 illustrating an operation of a control device according to the second embodiment of the present invention.

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

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

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 illustrating a configuration of a levitating body relay station according to a third embodiment of the present invention.

[Explanation of symbols]

 1 levitated base station, 2a, 2b, 2c levitated relay station, 3, 3a, 4a, 5a fixed base station, 8, 9a, 9b mobile communication switchboard, 10, 10a control device, 31-36, 41-43, 51 mobile device, 60, 61 home memory.

Claims (10)

[Claims] 1. A mobile communication system in which a fixed base station connected to a network and a mobile station existing in an area of the fixed base station communicate via a wireless channel, wherein a radio channel that does not cause interference in the fixed base station is set. And a mobile base station that communicates with the mobile device via the wireless channel, wherein the mobile base station is connected to the network. 2. A mobile communication system in which a plurality of fixed base stations connected to a network and a mobile station existing in an area of the plurality of fixed base stations communicate via a radio channel. A radio channel with little traffic and no interference at the second fixed
A mobile communication system, comprising: a mobile relay station capable of relaying to an area of a fixed base station, wherein the mobile relay station is connected to the network. 3. A mobile communication system in which a plurality of fixed base stations connected to a network and a mobile station located in an area of the plurality of fixed base stations communicate via a radio channel. A mobile relay station that converts a wireless channel with less traffic into a wireless channel that does not cause interference in the second fixed base station and relays the converted wireless channel to an area of the second fixed base station, wherein the mobile relay station is connected to the network; A mobile communication system characterized by being performed. 4. The mobile communication system according to claim 1, wherein the mobile base station moves in the air. 5. A control device for controlling movement of the mobile base station or the mobile relay station based on a communication state, wherein the control device controls an altitude of the mobile base station or the mobile relay station to control the altitude of the mobile base station or the mobile relay station. The mobile communication system according to claim 4, wherein an area of a mobile base station or the mobile relay station is changed. 6. The mobile communication system according to claim 1, further comprising a control device that controls the movement of the mobile base station or the mobile relay station based on a communication state. 7. The mobile communication system according to claim 5, wherein the communication state is presence or absence of congestion in each fixed base station. 8. The control device predicts the occurrence / non-occurrence of congestion in each fixed base station based on the position of each mobile device and the position of the area of each fixed base station, and according to the prediction result, the mobile base station or The mobile communication system according to claim 7, wherein the mobile relay station is moved. 9. A control console comprising an operator and controlling the control device according to the operation of the operator, wherein the controller is configured to control the mobile base station or the mobile station according to the operation of the control console. The mobile communication system according to claim 7, wherein the movement of the relay station is controlled. 10. The mobile communication system according to claim 1, wherein said mobile base station is portable.