JP2002159055A - Mobile communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mobile communication system which is improved in communication efficiency by restraining an increase in handover of speaking channels with an increment in the traveling speed of a mobile station and lightening a load imposed on all communication networks. SOLUTION: A communication network is formed of a stationary layer composed of ground base stations installed on the ground and a mobile layer composed of mobile base stations which are movable in the air, where the mobile base station is moved at the prescribed speed in the same direction with a mobile that moves at a high speed so as to remove handover. A relative speed between a mobile station and a base station is detected, a mobile base station of a mobile cell or a ground base station of a ground cell is selected, corresponding to the detected relative speed, and a speaking channel is handed over to the selected mobile base station or the ground base station.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile communication system, and more particularly, to a mobile communication system formed of a mobile layer as a mobile cell network including mobile base stations and a mobile station moving at high speed. The present invention relates to a mobile communication system capable of performing the above communication with no or extremely few handovers.

[0002]

2. Description of the Related Art A conventional cell communication network in mobile communication employs a fixed layer system composed of a plurality of cells, and has a cover area of, for example, a microcell within 1 km and a cover area of several km. Macrocells.

[0003] Microcells and macrocells differ in the size of radio wave coverage, but do not differ in the order of access by mobile stations.

[0004] Radio waves from mobile stations are received by base stations of microcells or macrocells within the area, and incoming calls to the mobile stations are simultaneously sent from base stations of adjacent cells based on location registration information of the mobile stations. This is done by sending a call to

When the mobile station moves out of the cell in which the first call is established, the mobile station investigates the reception electric field and the available channel of the adjacent cell and sends the cell to the base station of a highly sensitive cell. Switching is performed by an instantaneous interruption (so-called handover). Therefore, in the mobile communication, a communication channel is switched by a communication line including only one level communication network including a micro cell and a macro cell.
Further, since the mobile station can talk over only one mobile communication network, it is only on the sea near the ground and land.

In recent years, with the development of mobile communication, the importance of data communication by computers as well as voice communication has been increasing. In addition, the amount of communication data in image information transmission by multimedia or the like increases, and it is desired to increase the communication speed and improve the communication quality.

[0007] Further, when comparing the moving speeds, it is found that a person has a speed of 4
Because the speed range changes greatly, such as 100 km for cars, 100 km for cars, and 270 km per hour for high-speed trains, mobile communications are calls that can be performed from high-speed trains and other high-speed trains where people walk and make voice calls. There is a demand for a response up to data communication.

In a conventional terrestrial cell network using microcells or macrocells (for example, the coverage area of a macrocell is 5 km in diameter), handover due to speech channel switching is performed once or once per hour when a person walks. But a car with a speed of 100 km / h is about 23 times and a speed of 27 km / h
A high-speed railway of 0 km requires switching about 63 times.

A conventional cell base station is fixedly installed in a building, a steel tower, or the like on the ground, and the radio coverage area of the cell is fixed.

[0010]

The call channel switching is performed in three stages: detection of a mobile station moving to a cell, determination of a preceding cell, selection of an empty channel in the cell, and channel switching command to the mobile station. Procedure is included. Therefore, when the moving speed increases, the switching of the communication channel becomes complicated, and the area of the transmission signal for transmitting the information decreases. That is, the load on a small-layer communication network such as a micro-layer and a macro-layer may increase, and the communication efficiency may decrease.

If there is no free channel during handover to the base station of the next cell while moving, communication may be disconnected.

Accordingly, the present invention provides a communication network having a movable base station (referred to as a mobile base station), in which the mobile base station moves at a predetermined speed in the same moving direction as a moving body moving at a high speed. Accordingly, it is an object of the present invention to provide a mobile communication system capable of performing communication for a long time without handover or with significantly less handover.

Further, a relative speed between the mobile station and the base station is detected, and a mobile base station of a mobile cell or a ground base station of a terrestrial cell is selected in accordance with the detected relative mobile speed. An object of the present invention is to provide a mobile communication system with high communication efficiency by reducing the frequency of switching communication channels and reducing the load on the entire communication network by performing handover to a station or a ground base station.

[0014]

SUMMARY OF THE INVENTION A mobile communication system according to the present invention is a mobile communication system comprising a fixed layer as a ground cell network comprising ground base stations provided on the ground and a mobile base station capable of moving in the air. It has a communication line formed by forming a communication network by a mobile layer as a cell network, and a mobile station connected to the communication line so as to be able to communicate with each other.

Further, the mobile base station capable of moving in the air of the mobile communication system according to the present invention comprises a stratospheric platform station or an aircraft station capable of moving at a predetermined altitude at a predetermined speed in a predetermined direction. is there. .

The mobile base station of the mobile communication system according to the present invention communicates with a mobile station moving on a predetermined route.

Also, the mobile communication system according to the present invention includes relative speed detecting means for detecting a relative speed between the mobile station and the mobile base station, and the mobile communication system according to the relative moving speed detected by the relative speed detecting means. The mobile base station of the mobile layer or the ground base station of the fixed layer is selected, and handover is performed to the selected mobile base station or ground base station.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a mobile communication system according to the present invention will be described with reference to the drawings.

FIG. 1 shows a terrestrial base station 10 provided on the ground.
1 is a diagram showing a communication network formed by a terrestrial cell network E made up of a mobile base station 3 and a mobile cell network S made up of mobile base stations 3 that can move in the air. The ground base station 10 provided on the ground
Is hereinafter referred to as a fixed layer E, and a mobile cell network S including a mobile base station 3 capable of moving in the air is referred to as a mobile layer S.

As shown in FIG. 1, the communication network of the mobile communication system according to the present embodiment has a fixed layer E composed of cells C provided on the ground and having a narrow radio communication coverage area.
And a moving layer S composed of cells C having a larger coverage area than the cells C of the fixed layer E.

A large number of cells C exist in the fixed layer E and the mobile layer S, and the cells C in each layer have substantially the same radio communication coverage area. For example, the cells EC1 and EC2 of the fixed layer E shown in FIG.
And SC2 are areas of the same scale, but the fixed layer E
EC1 in the first layer and SC1 in the moving layer S are not the same area scale. Then, the fixed layer E shown in FIG.
Is the EC cell (where n = 1, 2, 2)
..), And the n-th cell C in the moving layer S is shown as SCn (where n = 1, 2,...).

The communication network has a hierarchical structure in which a mobile layer S as a mobile cell network S is arranged so as to overlap with a fixed layer E as a terrestrial cell network E.

Next, the base station of the cell C constituting each layer will be described.

The base station of cell C is mobile station 1 (FIGS. 5 and 6).
The mobile station 1 communicates wirelessly with the mobile station 1.
Is a mobile terminal communication device that is portable and can perform voice communication and data communication, and is configured to perform voice communication and data communication with the base station of the cell C.

The base station of the cell C of the fixed layer E as the terrestrial cell network E is the ground base station 10, and the base station of the cell C of the mobile layer S as the mobile cell network S moves and flies over the stratosphere 20 km above the ground. Mobile base station 3 attached to a stratospheric platform consisting of a flying aircraft or airship
(Stratospheric platform station 3). However, since the fixed layer E and the mobile layer S of the mobile communication system according to the present embodiment are characterized by having a hierarchical structure, they are all dependent on the height of the antenna of the base station and the magnitude of the transmission power. It is not decided. However, this is because the range of wireless communication emitted from the mobile base station 3 of the mobile layer S is configured to be able to variably set the angle and range at which wireless is emitted. The mobile base station 3 is a stratospheric platform station 3
However, even if fixed point staying is not possible, a jet fighter or an aircraft is within the flight range as long as the flight distance is about 20 km, so that the present invention can be implemented. Therefore, they are also referred to as aircraft stations.

The ground coverage area of the ground base station 10 which is the base station of the cell C of the fixed layer E of the mobile communication system according to the present embodiment is about 5 km in diameter, and is the base station of the cell C of the mobile layer S. A certain stratospheric platform station 3
Is 227 Km in diameter when the elevation angle is 10 degrees.

The stratospheric platform station 3 is hereinafter referred to as an SPF station 3. Figure 2 shows the altitude of the SPF station 3 at 20 km
FIG. 4 is a diagram showing an area in which a call can be made in FIG.

As shown in FIG. 2, the SPF station 3 has a communication area within an elevation angle (elevation angle) of 10 degrees from the ground. For this reason, the coverage area of the SPF station 3 has a diameter of 227 Km on the ground where the moving body 2 such as a car or a high-speed rail moves, and the coverage area at an altitude of a jet airliner flying over 10 Km is approximately 113 Km. .

Next, the stratospheric platform station 3 (SPF station 3) which is the mobile base station 3 of the cell C of the mobile layer S will be described with reference to FIG.

FIG. 3 shows a stratospheric platform station 3 (SPF station 3) which is the mobile base station 3 of the cell C of the mobile layer S.
FIG. 2 is a block diagram showing the configuration of FIG.

As shown in FIG. 3, the solar cell panel 3a
Is a device that is attached to the outer periphery of the platform and converts solar energy into electric energy.
The electric energy from the solar cell panel 3a is
b, and is supplied from the battery 3b as power to the driving unit 3c, the flight control unit 3f, the communication control unit 3k, and other components. However, in FIG. 3, the power supply destination of the battery 3b is shown only to the drive unit 3c, and the supply of power to each unit other than the drive unit 3c is not shown. The driving unit 3c is configured by an electric motor or the like, and transmits a rotational force to the thrust generating unit 3d and the direction control unit 3e. The thrust generating unit 3d rotates the propeller by the rotational force from the driving unit 3c to generate a thrust. The direction control unit 3e controls the change in the moving direction of the stratospheric platform station 3 and the ascent and descent by moving the rudder and the elevating and lowering rudder by the rotational force from the driving unit 3c. The drive unit 3c is adapted to generate a rotational force in a timely manner according to a control signal from a flight control unit 3f that controls the flight of the stratospheric platform station 3. The flight control unit 3f has a built-in computer, and has a GPS 3g (G
local Positioning System)
Based on its own position information and the flight information from the ground received by the flight communication device 3h, the driving unit 3c is controlled based on a flight control program stored in a storage device (not shown), and the stratospheric platform station 3 Is to perform a predetermined flight. Ground SPF controller 6
(Shown in Figure 5) receiving flight information and ground SPF
Transmission of the flight information to the control device 6 is performed by the antenna 3m and the flight communication device 3h.

As described above, the stratospheric platform station 3 as the mobile base station 3 is configured to be able to move in the stratosphere at a predetermined altitude and at a predetermined speed in a predetermined direction.

The communication device for performing communication with the mobile station 1 in the stratospheric platform station 3 and communication with the mobile cell controller 5 (shown in FIG. 5) on the ground has the following configuration.

Antenna 3m and mobile station communication device 3i
Performs wireless communication with the mobile station 1, and the antenna 3m and the terrestrial base station communication device 3j perform wireless communication with the terrestrial mobile cell control device 5. Further, the mobile station communication device 3i and the terrestrial base station communication device 3j are connected to the communication control unit 3k, and the communication control unit 3k operates between the mobile station communication device 3i and the terrestrial base station communication device 3j. It exchanges and controls communication information.

Next, the flight speed of the stratospheric platform station 3 (SPF station 3) as the mobile base station 3 will be described with reference to FIGS. 4 (a) and 4 (b).

The stratospheric platform station 3 traverses the stratosphere at an altitude of 20 km above the ground in a windless state with a maximum ground speed of 80 m.
/ S (288 km / h). However, in the stratosphere, for example, over Japan, a wind flow of 40 m / s or less is observed throughout the year. FIG. 4A shows the stratospheric platform station 3.
Is a diagram showing a state of flight in a complete forward wind at a wind speed of 40 m / s. FIG. 4B is a diagram showing a state in which the stratospheric platform station 3 flies in a complete headwind at a wind speed of 40 m / s. Assuming that the range of the flight speed of the stratospheric platform station 3 is 0 to 80 m / s, the control range of the ground speed of the stratospheric platform station 3 in the complete normal wind condition in FIG. 4A is 40 m / s (144 km / h). ) To 120 m / s (432 km / h), and the control range of the ground speed of the stratospheric platform station 3 in the complete headwind condition in FIG. 4B is −40 m / s (−144 km / h).
h) to 40 m / s (144 Km / h).

For example, along a high-speed train operating at 270 km / h, the stratospheric platform station 3
When flying at 70 km / h, the relative speed between the high-speed railway and the stratospheric platform station 3 becomes zero.

The stratospheric platform station 3 can stop at a fixed point in the stratosphere by controlling the propulsion force with respect to the wind direction.

Next, the configuration of the mobile communication system will be described with reference to FIG. FIG. 5 is a block diagram showing the configuration of the mobile communication system according to the present invention.

As shown in FIG. 5, the terrestrial base station 10 of each cell (EC1 to ECn) of the fixed layer E includes a terrestrial cell control device 4 that supervises and controls the terrestrial base station 10 of the cell C of the fixed layer E. Mobile base station 3 of each cell (SC1 to SCn) of mobile layer S
The (SPF station 3) is connected to the mobile cell control device 5 that controls the mobile base station 3 of the cell C of the mobile layer S via a wireless line.

Each of the cell controllers of the terrestrial cell controller 4 and the mobile cell controller 5 is connected to a central controller 7 for controlling handover of a base station between layers or within a layer. The device 7 is connected to an exchange and connected to a public line network.

Also, the mobile base station 3 (SP
The F station 3) is connected to the SPF control device 6 that controls the flight of the SPF station 3 by a wireless line.

The terrestrial cell controller 4 and the mobile cell controller 5 are collectively referred to as a cell controller.

Next, the configuration of the mobile station 1 that performs radio communication with the base station of the cell C in each layer will be described with reference to the block diagram of FIG. The communication scheme between the base station of each cell C and the mobile station 1 is CDMA (Code Division Multi Multi).
pe Access) system.

As shown in FIG. 6, the mobile station 1 includes an antenna 1f for transmitting and receiving radio waves, a transmission / reception distribution unit 1g for distributing radio waves, and a receiving unit 1h for amplifying and mixing received radio waves. A RAKE receiving section 1i for despreading and synthesizing signals, a channel processing section 1j for decomposing and synthesizing control channel signals and audio signals, and an audio processing section 1k for processing audio analog signals including microphones and speakers. A spreading section 11 for spreading the transmission data, a transmitting section 1m for performing quadrature modulation, power amplification and the like, and a frequency synthesizer section 1n for supplying a high frequency to the receiving section 1h and the transmitting section 1m.
And a control unit 1a as control means for performing calculation and control
A display unit 1b as a display unit including a liquid crystal driver and a liquid crystal display, and a keyboard (or function key) 1c as an operation unit for inputting a number or the like;
It has an input / output unit 1d connected to an external computer, a battery 1o for supplying power to each unit, and an accelerometer 1e.

The control unit 1a as a control means includes a CPU
(Central Processor Unit) or DSP (Digital Signal Processor), a memory for storing programs and data, an input / output circuit for input / output control of a display unit 1b and a keyboard (or function key) 1c, and time measurement. It is composed of a timer (clock) and the like. The units other than the accelerometer 1e are for performing voice communication and data communication with the base station of the cell C by the CDMA method.

As shown in FIG. 6, an accelerometer 1e as a moving speed detecting means measures acceleration during movement, and outputs a signal of the measured acceleration to the control unit 1a.
In step a, the speed of the mobile station 1 is calculated by integrating the acceleration signal of the accelerometer 1e.

The mobile station 1 has a channel processing unit 1j
The control unit 1a processes the reception level of the radio wave of the base station of the cell C of each layer from the control channel signal output from the control unit 1a, and the display unit 1b as a display means for displaying whether each layer can communicate is provided by each layer. The radio wave reception level of the cell C base station is also displayed. The caller can know which layer can talk on the display of the display unit 1b.

A keyboard (or function key) 1c as an operation means has a built-in operation switch, and the caller operates the operation switch to a communicable layer to connect to the base station of the cell C in the layer. It is possible to request a connection and talk. Thus, the mobile station 1 of the mobile communication system according to the present embodiment can manually connect to the layer by manually operating the keyboard (or function key) 1c as an operation means, but automatically searches for a layer that can talk. Thus, it is configured to be connectable to the base station of the cell C.

Next, the handover between the mobile base stations 3 or the ground base station 10 in the communication between the mobile station 1 and the base station will be described.

First, a relative speed detecting means for detecting a relative speed between the mobile station 1 and the stratospheric platform station 3 will be described.

The relative speed detecting means for detecting the relative speed between the mobile station 1 and the stratospheric platform station 3 is controlled by the ground cell controller 4, mobile cell controller 5, SPF controller 6 and central controller 7 shown in FIG. It consists of a series of processes to be executed.

The relative speed detecting means of the mobile communication system according to the present invention detects the flight speed and the flight direction of the stratospheric platform station 3 as the mobile base station 3 and the movement speed and the movement direction of the mobile station 1. is there. That is, the stratospheric platform station 3 as the mobile base station 3
The flight speed and the flight direction are calculated from the position data from the GPS 3g mounted on the stratospheric platform station 3. Flight control unit 3 of stratospheric platform station 3
f is position data p at time t1 from GPS 3g.
The calculation is performed from the position data p2 at 1 and the time t2 to determine the flight speed and the flight direction. On the other hand, mobile station 1
Is calculated by integrating the acceleration data of the accelerometer 1e of the mobile station 1 by the control unit 1a. The moving direction of the mobile station 1 is the same as that of the ground base station 1 that receives radio waves from the mobile station 1.
Calculated according to the order in which 0 transitions to the adjacent ground base station 10. That is, as the mobile station 1 moves, the mobile station 1 shifts to the terrestrial base station 10 that can receive radio waves from the mobile station 1.
The moving direction of the mobile station 1 is calculated by storing the order of the transfer of the terrestrial base station 10 and comparing it with the installation position of the terrestrial base station 10.

Each data of the flight speed and the flight direction of the stratospheric platform station 3 is transmitted to the central controller 7 via the SPF controller 6, and the data of the moving speed of the mobile station 1 is transmitted via the mobile cell controller 5 to the central controller. 7 is transmitted.
Also, information on the moving direction of the mobile station 1 is transmitted to the ground cell control device 4.
The moving direction of the mobile station 1 is transmitted to the central controller 7 and is calculated by the central controller. Thus, the central control unit 7 detects the relative speed between the mobile station 1 and the SPF station 3 by calculating from each data of the moving speed and the moving direction.

Next, communication and handover between the high-speed railway and the mobile station 1 moving on the highway and the base station will be described with reference to FIG.
This will be described with reference to the flowcharts shown in FIGS.
The mobile station 1 moves together with the mobile unit 2 moving at a high speed on a predetermined route such as a high-speed railway or a highway. Moving body 2 running on the high-speed rail line and highway
Is determined by traveling on an up line or a down line, and the traveling route is fixed. On the other hand, the stratosphere platform station 3 as the mobile base station 3 has a flight route stored in advance so as to fly on a predetermined route such as a high-speed railway or a highway.

As shown in FIG. 7, the caller specifies the number of the connection destination using the operation switch of the keyboard 1C as the operation means shown in FIG. 6, that is, the function key for specifying the layer, and presses the transmission key. At this time, the control unit 1a of the mobile station 1 confirms whether or not the transmission of the moving layer is specified (step S1).
Issues a connection request signal to the mobile base station 3 (step S
2). If no moving layer is specified, a connection request signal is issued to the fixed-layer E ground base station 10 (step S).
3). After the mobile station 1 transmits a connection request signal to the mobile layer S in step S2, the mobile base station 3 of the mobile layer S that has received the signal requests the mobile station 1 to output the moving speed of the mobile station 1 itself. (Step S4). The mobile cell controller 5 outputs the received moving speed data of the mobile station 1 to the central controller 7, and the central controller 7 determines whether the mobile station 1 is moving at high speed based on the moving speed data of the mobile station 1. (Step S5). If it is determined that the mobile station 1 is moving at a high speed, the mobile station 1 issues an instruction to the mobile cell controller 5 so that the mobile station 1 can use the channel line with the mobile base station 3. If it is determined that the mobile station 1 is not moving at high speed, the process proceeds to step S11.

Further, after the mobile station 1 transmits a connection request signal to the fixed layer E in step S3, the terrestrial base station 10 of the fixed layer E, which has received the signal, transmits the moving speed of the mobile station 1 itself to the mobile station 1. (Step S)
6). The ground cell control device 4 outputs the received moving speed data of the mobile station 1 to the central control device 7,
Determines whether the mobile station 1 is moving at high speed based on the moving speed data of the mobile station 1 (step S7). If it is determined that the mobile station 1 is moving at high speed, it is determined whether the mobile station 1 is within the service area of the mobile layer S (step S8). The control unit 4 controls the mobile station 1 for the mobile cell control unit 5
Is instructed to perform handover (step S9),
An instruction is issued so that the mobile station 1 can use the channel line with the mobile base station 3 (step S10). If it is determined in step S7 that the mobile station 1 is not moving at high speed, an instruction is issued so that the mobile station 1 can use the channel line with the mobile base station 10 (step S11).

Next, when the mobile station 1 is communicating with the fixed layer E ground base station 10, step S shown in FIG.
Move to 20. If the mobile station 1 is communicating with the mobile base station 3 of the mobile layer S, step S40 shown in FIG.
Move to

The mobile station 1 is a fixed layer E ground base station 10
When the call is established, the ground cell control device 4 stores the time (time) of the start of the call in the storage device (not shown) (step S20 in FIG. 8). Then, a call is started (step S21). During a call, the mobile station 1 detects a carrier level (step S22) and determines whether the carrier level is equal to or higher than a specified value (step S2).
3). If the carrier level is equal to or less than the specified value, the process proceeds to step S26. If the carrier level is equal to or higher than the specified value, the communication quality is inspected (step S24), and it is determined whether the communication quality level is equal to or higher than the specified value (step S25). If the call quality level is equal to or higher than the specified value, it is determined that communication between the mobile station 1 and the ground base station 10 is normal, and the procedure from step 22 is repeated. If the call quality level is below the specified value, it is determined that the call state has deteriorated,
The time (time) at that time is stored in the storage device of the ground cell controller 4 (step S26).

Next, the ground cell controller 4 calculates a call holding time t1 from the call start time to the communication degradation occurrence time (step S27), and notifies the central controller 7 of the call holding time t1. The central controller 7 sets the call holding time t
The mobile station 1 determines the moving speed of the mobile station 1 by comparing 1 with the preset reference call holding time Tv (step S28).
The determination of the moving speed of the mobile station 1 is based on the call holding time t1.
Is shorter than the reference call holding time Tv, it is determined that the speed is high.

Next, when the central controller 7 determines that the mobile station 1 is moving at a high speed in step S28,
The ground base station 10 requests the mobile station 1 to transmit the moving speed (step S29). It is determined whether the mobile station 1 is moving at a high speed based on the moving speed from the mobile station 1 (step S30). If it is determined that the mobile station is moving at high speed, it is checked whether the mobile station is in the service area of the mobile base station 3 (step S3).
1) If it is located in the service area, handover to the mobile base station 3 is performed (step S32). If it is determined that the vehicle is not moving at high speed, or if it is out of the service area, the handover to the ground base station 10 is performed (step S33).

Next, when the mobile station 1 establishes a call with the mobile base station 3 of the mobile layer S, the mobile cell control device 5
The call start time (time) is stored in the storage device (step S40 in FIG. 9). Then, a call is started (step S41). Central controller 7 instructs terrestrial base station 10 to receive the radio wave of mobile station 1 (step S4).
2). The central control device 7 records the temporal change of the transition of the terrestrial base station 10 that receives the radio wave from the mobile station 1, and detects the moving direction of the mobile station 1 by the transition of the terrestrial base station 10 (step S43). . It is checked whether the detected moving direction of the mobile station 1 is the same as the moving direction of the mobile base station 3 (step S45). If the moving directions are the same, the process proceeds to step S48. If the direction of movement is different,
The mobile base station 3 that is moving in the same direction as the mobile station 1 is selected (step S46), and handover to the selected mobile base station 3 is performed (step S47).

Next, in step S48, the relative speed between the mobile station 1 and the mobile base station 3 is detected (step S48). The relative speed is detected by the above-described relative speed detecting means. Since the mobile station 1 is located in the radio coverage area of the ground base station 10 in step S43, the position of the mobile station 1 can be specified from the installation position of the ground base station 10.

Next, based on the relative speed calculated in step S48 and the position of the mobile station 1, the time when the mobile station 1 is located outside the coverage area of the mobile base station 3, that is, the time when the handover to another mobile base station 3 is performed. (Step S4)
9). It is confirmed whether it is time for handover (step S50), and if it is time for handover, handover to a predetermined base station is performed (step S53). If it is not time to perform the handover, the communication quality between the mobile station 1 and the mobile base station 3 is checked (step S51). If the communication quality is equal to or higher than the specified value (step S52), the process proceeds to step S50. If the call quality is equal to or less than the specified value, the process proceeds to step S53 to perform handover to another base station.

As described above, communication and handover between the mobile station 1 moving at high speed and the base station in each layer are performed.

Next, an example of handover between layers during movement by the mobile unit 2 will be described with reference to FIG.

As shown in FIG. 10, a moving body (high-speed railway)
The mobile station 1 that moves with the mobile station 1
Stratospheric platform station 3 as one mobile base station 3
After the call is established, the central control unit 7
Is instructed to receive the radio wave of the mobile station 1 to the ground base station 10 of the cell EC1. As the mobile unit 2 moves, the cell C of the fixed layer E that can receive the radio wave of the mobile station 1
Shifts from the cell EC1 to the cell EC2. The moving direction (up or down) of the mobile unit 2 is detected by the transfer of the cell C. It is checked whether the detected moving direction of the mobile station 1 is the same as the moving direction of the mobile base station 3. If the moving directions are the same, the relative speed between the mobile station 1 and the stratospheric platform station 3 is calculated. . Further, since the position of the mobile station 1 is located within the radio coverage area of the cell EC2, the position of the mobile station 1 is specified from the installation position of the ground base station 10.

Next, from the calculated relative speed and the position of the mobile station 1, the time at which the mobile station 1 is located outside the radio coverage area of the stratospheric platform station 3, that is, the time at which the mobile station 1 is handed over to another mobile base station 3 is calculated. I do. If it is time to perform a handover, the handover to the stratospheric platform station 3 of the cell SC2 is performed.

As described above, since the stratospheric platform station 3 moves on the mobile station 1, the number of handovers can be reduced, and the handover time can be predicted, so that the efficiency of the communication line can be improved.

FIG. 11 is a diagram showing the number of handovers at the time of high-speed movement of a high-speed rail and a high-speed car as the mobile unit 2 with respect to the moving speed of the stratospheric platform station 3 (SPF station 3). However, the altitude of SPF station 3 is 20K
m, the communication range is 227 km in diameter, the talking time is 1 hour, 270 km / h for high-speed railway and 10 h / h for high-speed cars.
The moving speed was 0 km. Further, the lower end of the speed of the high-speed railway and the high-speed car indicates the relative speed with the SPF station 3.

As shown in FIG. 11, the number of handovers between the SPF station 3 of the high-speed railway and the high-speed car during one hour of talk time is 1 or less, and no handover occurs.
As a result, even when the mobile station moves at a high speed, a stable call and data communication can be performed because a handover is not required.

[0072]

As described above, according to the mobile communication system of the present invention, a mobile station and a mobile base station on a mobile moving on a predetermined route have a predetermined speed in the same moving direction. , Communication can be performed for a long time without handover.

The relative speed between the mobile station and the base station is detected, and the mobile base station of the mobile layer or the ground base station of the fixed layer is selected according to the detected relative mobile speed, and the selected mobile base station is selected. Alternatively, by handing over to a ground base station, the frequency of switching between communication channels can be reduced, the load on the entire communication network can be reduced, and communication efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a communication network in which a fixed layer (terrestrial cell network) and a mobile layer (mobile cell network) are arranged in an overlapping manner.

FIG. 2 shows a stratospheric platform station (S) at an altitude of 20 km and an elevation angle (elevation angle) of 10 degrees.
It is a figure which shows the area which can communicate (PF station).

FIG. 3 is a block diagram illustrating a configuration of a stratospheric platform station (SPF station) that is a mobile base station of a cell C in a mobile layer.

FIG. 4A shows the stratospheric platform station (S
(PF station) is a diagram showing a state of flight in a complete normal wind at a wind speed of 40 m / s, and (b) is a diagram showing a state of the stratospheric platform station flying in a complete headwind at a wind speed of 40 m / s. is there.

FIG. 5 is a block diagram showing a configuration of a mobile communication system according to the present invention.

FIG. 6 is a block diagram illustrating a configuration of a mobile station.

FIG. 7 is a flowchart showing a handover between a mobile station and a layer.

FIG. 8 is a flowchart showing a handover when a mobile station is communicating with a fixed layer.

FIG. 9 is a flowchart showing a handover when a mobile station is communicating with a mobile layer.

FIG. 10 is a diagram illustrating an example of a handover during movement by a moving object.

FIG. 11 is a diagram showing the number of handovers at the time of high-speed rail and high-speed vehicle movement with respect to the moving speed of the SPF station.

[Explanation of symbols]

Reference Signs List 1 mobile station 1a control unit 1b display unit 1c keyboard (or function key) 1d input / output unit 1e accelerometer 1f, 3m antenna 1g transmission / reception wave distribution unit 1h reception unit 1i RAKE reception unit 1j channel processing unit 1k audio processing unit 11 diffusion processing Unit 1m transmission unit 1n frequency synthesizer unit 1o, 3b battery 2 mobile unit 3 mobile base station (stratospheric platform station, SPF station or aircraft station) 3a solar cell panel 3c driving unit 3d thrust generator 3e direction control unit 3f flight control unit 3g GPS 3h Flight communication device 3i Mobile station communication device 3j Ground base station communication device 3k Communication control unit 4 Ground cell control device 5 Mobile cell control device 6 SPF control device 7 Central control device 10 Ground base station E Fixed layer (ground Cell network) S Moving layer (mobile cell network) C cell

Continued on the front page F term (reference) 5K051 AA01 CC07 DD15 FF04 FF19 GG06 5K067 AA33 BB04 BB43 DD20 DD44 EE02 EE10 EE12 EE41 HH22 JJ56 5K072 AA15 BB13 DD00 DD11 DD16

Claims (4)

[Claims] 1. A communication network is formed by a fixed layer as a terrestrial cell network comprising terrestrial base stations provided on the ground and a mobile layer as a mobile cell network comprising mobile base stations capable of moving in the air. A mobile communication system comprising: a communication line configured; and a mobile station connected to the communication line so as to be able to communicate with each other. 2. The mobile base station capable of moving in the air comprises a stratospheric platform station or an aircraft station capable of moving at a predetermined altitude at a predetermined speed in a predetermined direction. Mobile communication system. 3. The mobile communication system according to claim 1, wherein the mobile base station communicates with a mobile station moving on a predetermined route. 4. The mobile communication system according to claim 1, further comprising a relative speed detecting means for detecting a relative speed between the mobile station and the mobile base station, wherein the relative speed is detected by the relative speed detecting means. A mobile communication system, wherein a mobile base station of the mobile layer or a ground base station of the fixed layer is selected, and handover is performed to the selected mobile base station or ground base station.