JP7482755B2 - Mobile communication system, mobile station, and base station - Google Patents

Description

This disclosure relates to a mobile communication system, a mobile station, and a base station that perform wireless communication using a multiple-station simultaneous transmission method.

In a mobile communication system, a service area is made up of wireless zones operated by multiple base stations. Here, a wireless zone refers to the range within which a base station can communicate. The communication methods used in a mobile communication system include a method in which a base station that operates independently in each wireless zone communicates wirelessly with a mobile station, and a multi-station simultaneous transmission method in which multiple base stations transmit the same signal at the same frequency to a mobile station. The multi-station simultaneous transmission method may be adopted when the amount of simultaneous communication in which a base station simultaneously communicates with multiple mobile stations within a service area is low, or when broadcast communication is often performed within the service area. The multi-station simultaneous transmission method ensures high frequency utilization and high throughput with low transmission power, and can ensure roughly uniform transmission quality throughout the entire service area.

In the past, in mobile communication systems that use a multi-station simultaneous transmission method, technology has been disclosed that uses transmission diversity to ensure high-quality communication even at the boundaries of wireless zones (see, for example, Patent Document 1).

JP 2002-300097 A

Conventionally, mobile communication systems that use simultaneous multi-station transmission are characterized by transmitting the same signal at the same frequency from multiple base stations to mobile stations, and therefore have the restriction that only one mobile station can communicate with a base station within a service area. This restriction was tolerated because the simultaneous multi-station transmission method was originally adopted because the amount of simultaneous communication within a service area was low, or because broadcast communication was often performed within a service area.

However, in recent years, there has been an increasing trend for mobile stations to transmit fault information, location information, and monitoring information to base stations, leading to an increased demand for multiple mobile stations to be able to communicate with base stations simultaneously. When multiple mobile stations each transmit data to a base station at their own timing, a situation may arise in which the base station receives data transmitted from multiple mobile stations simultaneously. Because all mobile stations use the same frequency, when multiple mobile stations communicate with a base station simultaneously, they interfere with each other, causing communications disruption and degrading communication quality.

On the other hand, when the service area is wide, if multiple mobile stations are actually located in different radio zones and are far apart from each other, the impact of interference at the base station is minor, so there may be no problem with multiple mobile stations communicating with the base station simultaneously. However, a mobile station cannot determine whether its own communication with the base station will interfere with the communication of other mobile stations. Therefore, in the past, a mobile station had to put its own communication on hold when another mobile station was communicating with the base station, and there was a problem that multiple mobile stations could not communicate with the base station simultaneously.

The present disclosure has been made to solve these problems, and aims to provide a mobile communication system, a mobile station, and a base station that enable multiple mobile stations to communicate simultaneously with a base station within a service area established using a multiple-station simultaneous transmission method.

In order to solve the above problems, the mobile communication system according to the present disclosure is a mobile communication system including a plurality of base stations, a plurality of mobile stations capable of wireless communication with each base station using a multiple-station simultaneous transmission method, and a central device communicatively connected to each base station, in which a communicating mobile station that is in communication with a base station transmits location information of the communicating mobile station to the central device via the base station, and the central device calculates an interference area that may interfere with the communication of the communicating mobile station based on the location information of the communicating mobile station, and transmits information on the calculated interference area to each mobile station via each base station.

According to the present disclosure, multiple mobile stations can simultaneously communicate with a base station within a service area established using a multiple-station simultaneous transmission method.

1 is a diagram showing an example of the configuration of a mobile communication system according to a first embodiment; FIG. 2 is a block diagram showing an example of a configuration of a mobile station according to the first embodiment. 2 is a block diagram showing an example of the configuration of a central device according to the first embodiment; A figure showing an example of the configuration of a mobile communication system according to embodiment 2. FIG. 11 is a block diagram showing an example of the configuration of a mobile station according to a second embodiment. FIG. 11 is a block diagram showing an example of the configuration of a base station according to embodiment 2. A figure showing an example of the configuration of a mobile communication system according to embodiment 3. A figure showing an example of the hardware configuration of a mobile communication system according to embodiments 1 to 3. A figure showing an example of the hardware configuration of a mobile communication system according to embodiments 1 to 3.

<First embodiment>
<Configuration>
Fig. 1 is a diagram showing an example of the configuration of a mobile communication system according to embodiment 1. The mobile communication system according to embodiment 1 employs a multiple station simultaneous transmission method.

As shown in FIG. 1, the mobile communication system includes base stations 1 to 5, mobile stations 7 and 9, a central device 10, and equipment 11.

Base station 1 has wireless zone 13, base station 2 has wireless zone 14, base station 3 has wireless zone 15, base station 4 has wireless zone 16, and base station 5 has wireless zone 17. Service area 12 is made up of wireless zones 13 to 17.

Mobile station 7 is mounted on train 6, and mobile station 9 is mounted on train 8. Mobile stations 7 and 9 are located within service area 12 and are capable of wireless communication with base stations 1 to 5. Here, communication from base stations 1 to 5 to mobile stations 7 and 9 is called downlink communication, and communication from mobile stations 7 and 9 to base stations 1 to 5 is called uplink communication.

The central unit 10 is communicatively connected to the base stations 1 to 5 via a wired network. The device 11 is communicatively connected to the central unit 10, and is capable of making calls or data communications with the mobile stations 7, 9 present within the service area 12 via the base stations 1 to 5 and the central unit 10. Note that although one device 11 is shown in FIG. 1, there may be multiple devices 11.

Figure 2 is a block diagram showing an example of the configuration of mobile station 7. As shown in Figure 2, mobile station 7 includes a transmitter 20, a receiver 21, a position detector 22, and a controller 23. Note that Figure 2 shows the configuration of mobile station 7 as a representative example, but mobile station 9 has the same configuration.

The transmitter 20 transmits uplink communication data to the base stations 1 to 5. Here, uplink communication data refers to data sent from the mobile station to the base station by uplink communication. The receiver 21 receives downlink communication data sent from the base stations 1 to 5. Here, downlink communication data refers to data sent from the base station to the mobile station by downlink communication.

The position detection unit 22 detects the position of the mobile station 7. The position detection unit 22 may detect the position of the mobile station 7 by the mobile station 7 itself from some kind of sign or the like, or may obtain information on the position of the mobile station 7 from another device that measures the position of the mobile station 7. The control unit 23 controls the transmission unit 20, the reception unit 21, and the position detection unit 22.

Figure 3 is a block diagram showing an example of the configuration of the central unit 10. The central unit 10 is a device that interconnects the base stations 1 to 5 and the device 11, and includes a control unit 24 as shown in Figure 3.

<Operation>
Next, the operation of the mobile communication system according to the first embodiment will be described with reference to Fig. 1. It is assumed that the mobile station 7 is present within the radio zone 13 of the base station 1. It is also assumed that the mobile station 7 has already started communication with the base station 1 and is performing voice or data communication with the device 11 via the central equipment 10.

The transmitter 20 of the mobile station 7 includes its own location information detected by the location detector 22 in uplink communication data and transmits the data to the base station 1. The base station 1 transmits the uplink communication data received from the mobile station 7 to the central device 10.

Based on the location information of the mobile station 7 included in the uplink communication data transmitted from the mobile station 7, the control unit 24 of the central device 10 calculates an area 18 (interference area) in which a mobile station other than the mobile station 7 may interfere with the uplink communication of the mobile station 7 that is already communicating when the mobile station other than the mobile station 7 performs uplink communication with one of the base stations 1 to 5. The area 18 is a part of the service area 12.

Any method may be used to calculate area 18, but for example, control unit 24 may calculate area 18 to be a range with a radius of 10 km centered on the position of mobile station 7. The distance from mobile station 7 is not limited to 10 km, and may be calculated in advance from an actual measurement or a known approximation formula for radio wave propagation loss (e.g., the Egli formula) and the actual station location.

The central device 10 transmits the area 18 information calculated by the control unit 24 to the base stations 1 to 5, including it in the downlink communication data used for communication with the mobile station 7. Because the service area 12 is constructed using a multiple-station simultaneous transmission method, the base stations 1 to 5 transmit the same data to the mobile station. Because the mobile station 9 is located within the service area 12, it is able to receive downlink communication data including the area 18 information sent from any of the base stations 1 to 5.

The receiver 21 of the mobile station 9 receives downlink communication data including information on the area 18. The controller 23 refers to the information on the area 18 included in the downlink communication data received by the receiver 21 and the position of the mobile station 9 detected by the position detector 22 to determine whether the mobile station 9 is in the area 18. If the controller 23 determines that the mobile station 9 is in the area 18, it suspends the transmission of uplink communication data to any of the base stations 1 to 5. On the other hand, if the controller 23 determines that the mobile station 9 is in an area 19 other than the area 18 within the service area 12, it transmits uplink communication data to any of the base stations 1 to 5. The area 19 is an area where there is almost no possibility that a mobile station other than the mobile station 7 will interfere with the uplink communication of the mobile station 7 when it performs uplink communication with any of the base stations 1 to 5.

Although the above describes a case where the central device 10 notifies the mobile station 9 of information on the area 18 calculated by the central device 10, information on the area 19 may also be notified to the mobile station 9. Also, the above describes a case where the control unit 24 of the central device 10 calculates the area 18, but the central device 10 may notify the mobile station 9 of the position of the mobile station 7 without calculating the area 18, and the control unit 23 of the mobile station 9 may calculate the area 18 based on the position of the mobile station 7.

＜Effects＞
From the above, according to the first embodiment, a mobile station that is about to start a new communication with a base station can determine whether or not there is a possibility of disturbing the uplink communication of a mobile station that is already communicating by receiving downlink communication data transmitted from the central device via the base station. As a result, a mobile station that is in an area where there is no possibility of disturbing the uplink communication of a mobile station that is already communicating can perform uplink communication. Therefore, in a service area established by adopting the multiple-station simultaneous transmission method, a plurality of mobile stations can simultaneously communicate with a base station, and the effect of improving the frequency utilization efficiency can be obtained.

<Embodiment 2>
In the first embodiment, the central device calculates an area where another mobile station may disrupt the uplink communication of the already communicating mobile station based only on the location information of the already communicating mobile station. In the second embodiment, the central device calculates an area where another mobile station may disrupt the uplink communication of the already communicating mobile station based on the transmission power of the mobile station, taking into account the reception strength at the base station.

Figure 4 is a diagram showing an example of the configuration of a mobile communication system according to embodiment 2. As in embodiment 1, the mobile communication system according to embodiment 2 has a service area 12 that employs a multiple-station simultaneous transmission method. Mobile stations 7 and 9 are present within service area 12.

The central unit 10 is communicatively connected to the base stations 1 to 5 via a wired network. The device 11 is communicatively connected to the central unit 10, and is capable of making calls or data communications with the mobile stations 7, 9 present within the service area 12 via the base stations 1 to 5 and the central unit 10. Note that although one device 11 is shown in FIG. 1, there may be multiple devices 11.

Figure 5 is a block diagram showing an example of the configuration of mobile station 7. As shown in Figure 5, mobile station 7 is characterized in that the transmitter 20 has a gain adjustment unit 29, and the receiver 21 has a gain adjustment unit 30. The rest of the configuration and operation are the same as in embodiment 1, so detailed explanations are omitted here. Note that Figure 5 shows the configuration of mobile station 7 as a representative example, but mobile station 9 also has the same configuration.

Gain adjustment units 29 and 30 adjust the gain. There are two types of gain: rated gain and 10 dB reduced gain. Gain adjustment units 29 and 30 change the gain according to the reception strength of downlink communication data received from the base station. Specifically, gain adjustment units 29 and 30 adopt the rated gain when they are far from a base station already communicating with the mobile station, and adopt the 10 dB reduced gain when they are near a base station already communicating with the mobile station. This makes it possible to avoid saturation of the receiving circuits in base stations 1 to 5 and mobile stations 7 and 9, and to prevent deterioration of communication quality.

Figure 6 is a block diagram showing an example of the configuration of base station 1. As shown in Figure 6, base station 1 has a transmitting unit 31 and a receiving unit 32. The receiving unit 32 also has a receiving electric field strength output unit 33. Note that Figure 6 shows the configuration of base station 1 as a representative, but base stations 2 to 5 also have the same configuration.

The transmitter 31 transmits downlink communication data to the mobile stations 7 and 9. The receiver 32 receives uplink communication data from the mobile stations 7 and 9. The reception field strength output unit 33 outputs the reception field strength when the uplink communication data is received from the mobile stations 7 and 9 to the central device 10.

<Operation>
Next, the operation of the mobile communication system according to the second embodiment will be described with reference to Fig. 4. It is assumed that the mobile station 7 is present within the radio zone 13 of the base station 1. It is also assumed that the mobile station 7 has already started communication with the base station 1 and is performing voice or data communication with the device 11 via the central equipment 10.

The transmitter 20 of the mobile station 7 includes its own location information detected by the location detector 22 in uplink communication data and transmits it to the base station 1. The base station 1 adds the received electric field strength at the time of receiving the uplink communication data to the uplink communication data received from the mobile station 7 and transmits it to the central device 10.

Based on the location information of the mobile station 7 included in the uplink communication data transmitted from the mobile station 7 and the reception electric field strength output by the reception electric field strength output unit 33 of the base station 1, the control unit 24 of the central device 10 calculates an area in which uplink communication of a mobile station other than the mobile station 7 with any of the base stations 1 to 5 may interfere with the uplink communication of the mobile station 7 already in communication. More specifically, the control unit 24 calculates two types of areas as areas in which uplink communication of a mobile station other than the mobile station 7 with any of the base stations 1 to 5 may interfere with the uplink communication of the mobile station 7 already in communication: an area in which a mobile station that is about to start new communication performs uplink communication at rated output, and an area in which a mobile station that is about to start new communication performs uplink communication at a 10 dB lower output.

In the example of FIG. 4, area 25 (interference area) indicates an area where a mobile station attempting to newly start communication may interfere with uplink communication of a mobile station 7 already in communication when it performs uplink communication at rated output. Area 26 indicates an area where a mobile station attempting to newly start communication is unlikely to interfere with uplink communication of a mobile station 7 already in communication when it performs uplink communication at rated output. Area 27 (interference area) indicates an area where a mobile station attempting to newly start communication may interfere with uplink communication of a mobile station 7 already in communication when it performs uplink communication at a 10 dB lower power. Area 28 indicates an area where a mobile station attempting to newly start communication is unlikely to interfere with uplink communication of a mobile station 7 already in communication when it performs uplink communication at a 10 dB lower power.

Area 25 and area 27 may be calculated by any method, but may be calculated, for example, by inputting the received electric field strength and the transmission power of the mobile station into a formula created using an approximation formula for actual measurement or known radio wave propagation loss (e.g., the Egli formula). In this case, the transmission power of the mobile station may be included in the uplink communication data. Areas 26 and 28 are areas other than areas 25 and 27 in service area 12.

The central device 10 transmits information about areas 25, 27 calculated by the control unit 24 to base stations 1-5, including it in the downlink communication data used for communication with the mobile station 7. Because the service area 12 is constructed using a multiple-station simultaneous transmission method, base stations 1-5 transmit the same data to the mobile station. Because the mobile station 9 is located within the service area 12, it is able to receive downlink communication data including information about areas 25, 27 sent from any of the base stations 1-5.

The control unit 23 of the mobile station 9 determines the transmission gain of the uplink communication data according to the reception strength of the downlink communication data. The control unit 23 then refers to the information on areas 25, 27 included in the downlink communication data received by the receiving unit 21 and the position of the mobile station 9 detected by the position detection unit 22 to determine whether the mobile station 9 is present within the area 25, 27. If the control unit 23 determines that the mobile station 9 is present within the area 25, 27, it suspends the transmission of the uplink communication data to any of the base stations 1 to 5. On the other hand, if the control unit 23 determines that the mobile station 9 is present in areas 26, 28 other than the areas 25, 27 within the service area 12, it transmits the uplink communication data to any of the base stations 1 to 5.

For example, if mobile station 9 is present near base station 1 that is already communicating with mobile station 7, the transmission gain of the uplink communication data transmitted from mobile station 9 is set to a 10 dB reduction. If mobile station 9 is present within area 27 shown in FIG. 4, the transmission of uplink communication data to any of base stations 1 to 5 is suspended.

For example, as shown in FIG. 1, when a mobile station 9 is located far from a base station 1, the reception strength of the downlink communication data that the mobile station 9 receives from the base station 1 is low, and therefore the mobile station is vulnerable to interference. Also, in the first embodiment, the transmission output of a mobile station attempting to start new communication is not taken into consideration, so the control unit 24 of the central device 10 calculates the area under the assumption that the transmission output of a mobile station attempting to start new communication is the rated output. Therefore, mobile stations attempting to start new communication are limited to being quite far away.

On the other hand, as shown in FIG. 4, when the mobile station 7 is located near the base station 1, the receiving electric field strength at the base station 1 is large and therefore resistant to interference. In the second embodiment, the central device 10 calculates the area taking into account the receiving electric field strength at the base station 1, so that it is possible to calculate a larger area as an area free from interference than in the first embodiment. Also, in the second embodiment, the control unit 24 of the central device 10 calculates an area where interference is possible taking into account the transmission output of a mobile station that is about to start new communication, so that for a mobile station that has reduced its transmission power by 10 dB, it is possible to calculate an even larger area as an area free from interference.

＜Effects＞
From the above, according to the second embodiment, it is possible to obtain the same effect as the first embodiment. Also, by taking into consideration the received electric field strength at the base station and the transmission gain at the mobile station, it is possible to determine whether or not there is a possibility of interfering with the uplink communication of a mobile station that is already in communication. Therefore, since a wider area than that of the first embodiment is determined as an area free from the possibility of interference, it is possible to obtain the effect of further improving the efficiency of frequency utilization.

<Third embodiment>
In the first and second embodiments, a case where a mobile station that is about to start a new communication judges whether or not it can communicate with a base station is described. In the third embodiment, a case where a plurality of mobile stations communicate in one service area, how each base station in the service area processes the uplink communication data received will be described.

Figure 7 is a diagram showing an example of the configuration of a mobile communication system according to embodiment 3. As in embodiments 1 and 2, the mobile communication system according to embodiment 3 has a service area 12 that employs a multiple-station simultaneous transmission method. Mobile stations 7 and 9 are present within service area 12. It is assumed that mobile station 7 has already started communication with base station 1, and is conducting voice or data communication with device 11 via central device 10. It is also assumed that mobile station 9 has started communication with the base station using the method described in embodiment 1 or 2.

The central unit 10 is communicatively connected to the base stations 1 to 5 via a wired network. The device 11 is communicatively connected to the central unit 10, and is capable of making calls or data communications with the mobile stations 7, 9 present within the service area 12 via the base stations 1 to 5 and the central unit 10. Note that although one device 11 is shown in FIG. 1, there may be multiple devices 11.

Base station 1 receives high-quality uplink communication data from mobile station 7, and base station 4 receives high-quality uplink communication data from mobile station 9. Also, base station 2 receives low-quality uplink communication data from mobile station 7, and base station 5 receives low-quality uplink communication data from mobile station 9. Base station 3 is unable to receive the uplink communication data of mobile station 7 and mobile station 9 due to interference between the uplink communication data of mobile station 7 and mobile station 9.

In conventional simultaneous multi-station transmission methods, since only one mobile station can communicate with a base station within one service area, it was sufficient to select and adopt from the uplink communication data received by each base station only one uplink communication data with the best communication quality, that is, the uplink communication data with the strongest received electric field strength and most likely to be used with an error correction function or an error detection function such as CRC. However, when there are multiple mobile stations within one service area that can communicate with a base station, it is necessary to adopt all of the uplink communication data from each mobile station. On the other hand, when multiple base stations are receiving the same uplink communication data, it is necessary to discard unnecessary uplink communication data to avoid duplication.

In the third embodiment, the control unit 24 of the central device 10 notifies each base station 1 to 5 of the base station group 34 (base stations 1 and 2) that receives uplink communication data from the mobile station 7, and the base station group 35 (base stations 4 and 5) that may receive uplink communication data from mobile stations other than the mobile station 7. The base station group 34 selects one piece of the most likely data from the uplink communication data received by each base station 1 and 2 included in the base station group 34 and transmits it to the central device 10. The base station group 35 selects one piece of the most likely uplink communication data from the uplink communication data received by each base station 4 and 5 included in the base station group 35 and transmits it to the central device 10. The base station 3 that is not included in the base station groups 34 and 35 does not transmit the received uplink communication data to the central device 10.

Here, we will explain a method for selecting the most probable data from among the uplink communication data received by each base station included in the base station group. In addition to the received uplink communication data, the base station also transfers the indicators (field strength, error correction indicator, error detection indicator) at the time of receiving the uplink communication data to other base stations, but only transfers the data with the best indicator. For example, when each base station is connected in a line and data (uplink communication data and indicators at the time of receiving the uplink communication data) is bucket-brigade, the data sent from the upstream base station is compared with its own data, and the better data is transferred to the downstream base station, thereby selecting the most probable uplink communication data. Also, when each base station is connected in a star shape, the device in the hub part has a data selection function, so that the most probable uplink communication data can be selected.

The control unit 24 of the central device 10 may set, for example, base stations 2 that exist within a predetermined range of a base station 1 that receives high-quality uplink communication data from a mobile station 7 as a base station group 34. The base station group 35 may also be set in the same manner.

In the third embodiment, the control unit 24 of the central unit 10 notifies the base stations 1 to 5 of the base station groups 34 and 35, and in the process of transmission from the base stations 1 to 5 to the central unit 10, the most likely uplink communication data is selected for each base station group, and the uplink communication data transmitted from each of the multiple mobile stations is transmitted to the control unit 24 of the central unit 10. However, this is not limited to the above. For example, the control unit 24 of the central unit 10 may not notify the base stations 1 to 5 of the base station groups 34 and 35, and may aggregate the uplink communication data received by all the base stations 1 to 5 in the central unit 10. In this case, the most likely uplink communication data may be adopted as the uplink communication data from the mobile station 7 from among the uplink communication data transmitted from each base station that received the uplink communication data from the mobile station 7, and the most likely uplink communication data may be adopted as the uplink communication data from the base station other than the mobile station 7 from among the uplink communication data transmitted from each base station that received the uplink communication data from the base station other than the mobile station 9.

＜Effects＞
From the above, according to the third embodiment, a plurality of base stations communicating with a plurality of mobile stations within one service area are grouped as a base station group for each mobile station. This makes it possible to reduce duplication of data transmitted from each base station to the central device. In addition, even within a service area that employs a multi-station simultaneous transmission method, a plurality of mobile stations can simultaneously transmit uplink communication data, thereby improving the efficiency of frequency utilization.

<Hardware Configuration>
The functions of the transmitter 20, receiver 21, position detector 22, and controller 23 in the mobile stations 7 and 9 described in the first embodiment are realized by processing circuits. That is, the mobile stations 7 and 9 include processing circuits for transmitting uplink communication data, receiving downlink communication data, detecting the position, and controlling each component. The processing circuit may be dedicated hardware, or may be a processor (also called a CPU (Central Processing Unit), central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, or DSP (Digital Signal Processor)) that executes a program stored in a memory.

When the processing circuit is dedicated hardware, as shown in FIG. 8, the processing circuit 36 may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination of these, and each of the functions of the corresponding transmission unit 20, reception unit 21, position detection unit 22, and control unit 23 may be realized by the processing circuit 36 individually, or each function may be realized together by a single processing circuit 36.

When the processing circuit 36 is the processor 37 shown in FIG. 9, the functions of the transmitter 20, receiver 21, position detector 22, and controller 23 are realized by software, firmware, or a combination of software and firmware. The software or firmware is written as a program and stored in memory 38. The processor 37 realizes each function by reading and executing the program recorded in memory 38. That is, the mobile station 7, 9 has a memory 38 for storing a program that results in the execution of the steps of transmitting uplink communication data, receiving downlink communication data, detecting the position, and controlling each component. It can also be said that these programs cause a computer to execute the procedures or methods of the transmitter 20, receiver 21, position detector 22, and controller 23. Here, memory may be, for example, non-volatile or volatile semiconductor memory such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), magnetic disk, flexible disk, optical disk, compact disk, DVD (Digital Versatile Disc), or any storage medium that will be used in the future.

Note that some of the functions of the transmitter 20, receiver 21, position detector 22, and controller 23 may be realized by dedicated hardware, and other functions may be realized by software or firmware.

In this way, the processing circuitry can realize each of the above-mentioned functions through hardware, software, firmware, or a combination of these.

The above describes the hardware configuration of the mobile stations 7 and 9 shown in Figure 2, but the same applies to the hardware configuration of the central device 10 shown in Figure 3, the mobile stations 7 and 9 shown in Figure 5, and the base station 1 shown in Figure 6.

Within the scope of this disclosure, each embodiment may be freely combined, modified, or omitted as appropriate.

1-5 base station, 6 train, 7 mobile station, 8 train, 9 mobile station, 10 central unit, 11 equipment, 12 service area, 13-17 radio zone, 18, 19 area, 20 transmitter, 21 receiver, 22 position detector, 23 control unit, 24 control unit, 25-28 area, 29, 30 gain adjustment unit, 31 transmitter, 32 receiver, 33 received field strength output unit, 34, 35 base station group, 36 processing circuit, 37 processor, 38 memory.

Claims (8)

A mobile communication system including a plurality of base stations, a plurality of mobile stations capable of wirelessly communicating with each of the base stations by a multiple-station simultaneous transmission method, and a central device communicatively connected to each of the base stations,
a communicating mobile station that is in communication with the base station transmits location information of the communicating mobile station to the central device via the base station;
A mobile communication system in which the central device calculates an interference area that has the potential to interfere with communication of the communicating mobile station based on the location information of the communicating mobile station, and transmits information about the calculated interference area to each of the mobile stations via each of the base stations. the base station adds a received electric field strength from the communicating mobile station to the location information and transmits the information to the central device;
The mobile communication system according to claim 1 , wherein the central device calculates the interference area for each transmission power that can be changed by the mobile station based on the location information and the received electric field strength. There are a plurality of communicating mobile stations,
2. The mobile communication system according to claim 1, wherein the central device groups base stations including a plurality of the base stations that may receive data from one of the communicating mobile stations based on location information of each of the communicating mobile stations, and adopts the data received by one of the base stations included in the grouped base station group. A mobile station used in a mobile communication system including a plurality of base stations, a plurality of mobile stations capable of wirelessly communicating with each of the base stations by a multiple-station simultaneous transmission method, and a central device communicatively connected to each of the base stations,
a communicating mobile station that is in communication with the base station transmits location information of the communicating mobile station to the central device via the base station;
A mobile station that receives information on interference areas that may interfere with communications of the communicating mobile station from the central device via each of the base stations, the information being calculated by the central device based on the location information of the communicating mobile station. The mobile station according to claim 4, wherein the central device receives the interference area for each transmission power that can be changed by the mobile station, the interference area being calculated by the central device based on the location information and the received electric field strength from the communicating mobile station, from the central device via each of the base stations. A base station used in a mobile communication system including a plurality of base stations, a plurality of mobile stations capable of wirelessly communicating with each of the base stations by a multiple-station simultaneous transmission method, and a central device communicatively connected to each of the base stations,
transmitting location information of a communicating mobile station received from the communicating mobile station, the mobile station being in communication with the base station, to the central device;
a base station that transmits to each of the communicating mobile stations information on interference areas that may interfere with communications of the communicating mobile stations, the information being calculated by the central device based on the location information of the communicating mobile stations. adding a received electric field strength from the communicating mobile station to the location information and transmitting the information to the central device;
7. The base station according to claim 6, wherein the central device transmits to each mobile station the interference area for each transmission power that can be changed by the mobile station, the interference area being calculated by the central device based on the location information and the received electric field strength from the communicating mobile station. There are a plurality of communicating mobile stations,
receiving information on a group of base stations, the group including a plurality of base stations which may receive data from one of the communicating mobile stations, the group being grouped by the central device based on location information of each of the communicating mobile stations;
The base station according to claim 6 , wherein one of the base stations included in each of the base station groups transmits the received data to the central device.

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