JP7296066B2 - local base station - Google Patents

Description

The present invention relates to local base stations.

Mobility as a Service (MaaS), which integrates different types of transport services into one mobile service that can be used on demand, is being considered. In this MaaS, transportation is cloud-based, and regardless of whether it is public transportation or not, and regardless of the operator, all transportation modes are treated as a single service and seamlessly connected. In this system, by interconnecting vehicles, vehicles can be used as hubs for the movement of people, goods, energy, and information. In addition, the user can use, for example, a smartphone application to search for and use means of transportation and routes, and to pay for fares and the like.

MaaS is supported by Information and Communication Technology (ICT) such as 5G communication system. This communication system is composed of a macro base station forming a macro cell, and a plurality of local base stations connected to the macro base station via communication links and forming small cells within the macro cell (for example, Japanese Unexamined Patent Application Publication No. 2017-143584).

Since the communication area of the local base station is relatively small, it is necessary to deploy a large number of base stations. For example, consider arranging the local base station at an intersection where automobiles can pass. In this case, as the power required for the local base station, for example, a method of diverting the system power supplied to the traffic light (power supplied from the commercial power distribution network owned by the electric power company) can be considered. However, it is said that there are 800,000 intersections nationwide where automobiles can pass without traffic lights, and securing power supply at these intersections is a problem. Moreover, when a disaster occurs, there is a high possibility that power cannot be supplied from the system power supply even at an intersection where a traffic light exists.

In particular, when a disaster strikes, it becomes difficult to secure power sources for local base stations, not just for MaaS, and communication systems may not function even if terminals are available. In addition, even if a portable local base station is brought into the disaster area for the purpose of grasping the disaster situation in real time, there is a high possibility that securing the power source will be an issue.

JP 2017-143584 A

SUMMARY OF THE INVENTION It is an object of the present invention to provide a local base station that can stably operate even in a place where it is difficult to secure a system power supply.

A local base station of the present invention includes a power supply unit, an antenna unit, a communication unit that operates by power supply from the power supply unit and performs information communication with one or more mobile terminals via the antenna unit, and acquires environmental information. and a control unit that controls the operation of the communication unit, the power supply unit has a generator that generates power from renewable energy, and the control unit controls the power consumption of the communication unit to be the above. The operation of the communication unit is controlled so as to be equal to or less than the power supply capacity of the power supply unit calculated based on the information from the environment sensor unit.

Since the local base station is powered by renewable energy, it can operate without power supply from the grid power supply. Also, the local base station predicts the amount of power that can be supplied from the power supply unit from the environmental information acquired by the environment sensor unit, and controls the operation of the communication unit. Therefore, even if the ability of the power supply unit to supply power drops due to changes in environmental conditions, it is possible to prevent the local base station from not functioning. Therefore, the local base station can stably operate even in a place where it is difficult to secure a system power supply.

The environment sensor section may have an illuminance meter, a weather gauge, and a thermometer, and the power generator may be a solar power generator. If the power generator is a solar power generator, the amount of power generated depends on the intensity of light received by the solar panel, the operating temperature of the solar cells, and changes in weather. Therefore, by configuring the environment sensor section to have an illuminance meter, a weather gauge, and a thermometer, it is possible to accurately predict the power supply capability from the power source, thereby further improving the operational stability of the local base station.

The power supply unit includes a secondary battery and a supercapacitor capable of storing electric power generated by the generator, and a switch for selecting a power supply for supplying power to the communication unit from the generator, the secondary battery, and the supercapacitor. and should be further provided. With the above configuration, the surplus power generated by the generator is stored in the secondary battery and the supercapacitor, and when the power from the generator drops, the stored power can be used, so the operation of the local base station is stable. can further improve performance. In addition, it is known that a secondary battery has a recovery effect of extending the battery life by, for example, disconnecting it from a circuit (opening state) for a certain period of time or more in a charged state. By using a secondary battery and a supercapacitor together, power can be supplied from the supercapacitor even in an open state in order to obtain the recovery effect of the secondary battery, so management for obtaining the above recovery effect can be easily performed. . Therefore, it is easy to extend the life of the secondary battery. Furthermore, since the power supply unit includes a supercapacitor that can be charged and discharged at high speed, it is possible to quickly adjust the storage of electric power in the power supply unit and the supply of electric power to the communication unit and the like.

The communication unit is preferably of a normally-off type. Since the power consumption of the communication unit can be suppressed by making the communication unit a normally-off type in this way, it is possible to further improve the operational stability of the local base station.

Preferably, the communication section has a power amplifier that controls the output of the antenna section, and the control section controls the output of the power amplifier. With the above configuration, the control unit can reduce the output of the power amplifier when the power supply capability of the power source is reduced. As a result, power consumption of the local base station can be suppressed, and stable operation of the local base station can be maintained.

Preferably, the communication section has a modulation/demodulation section capable of selecting a plurality of types of modulation schemes with different power consumptions, and the control section selects the modulation scheme of the modulation/demodulation section. With the above configuration, when the power supply capability of the power source is reduced, the control section can select a modulation method with low power consumption. As a result, power consumption of the local base station can be suppressed, and stable operation of the local base station can be maintained.

Preferably, the communication section has a mode selection section including a two-way communication mode, a transmission mode and a reception mode, and the control section selects the mode of the mode selection section. With the above configuration, it is possible to select an appropriate mode according to the presence or absence of a disaster and the power supply capacity of the power supply, so that maximum performance can be exhibited with limited power.

Preferably, the mode selection unit further includes a broadcast mode for simultaneous transmission to all mobile terminals, and a priority reception mode for preferentially receiving information from a specific mobile terminal. In this way, the mode selection unit further includes the broadcast mode and the priority reception mode, thereby making it easier to control the selection and concentration of functions under limited power.

The local base station can be suitably used in a mobility-as-a-service communication system.

As explained above, the local base station of the present invention can stably operate even in a place where it is difficult to secure a system power supply.

FIG. 1 is a schematic diagram showing the configuration of a mobility hub using local base stations according to one embodiment of the present invention. 2 is a block diagram showing the configuration of the local base station in FIG. 1. FIG. FIG. 3 is a schematic diagram showing the configuration of the power supply section in FIG. FIG. 4 is a graph showing an example of information stored in the database of the control unit of FIG. 1 as an image diagram. FIG. 5 is a graph showing an example of information stored in the database of the control unit in FIG. 1, different from that in FIG. 4, as an image diagram. FIG. 6 is a step diagram showing an example of a control method of the control unit in FIG.

Hereinafter, a local base station according to an embodiment of the present invention will be described with appropriate reference to the drawings.

[Mobility Hub]
The mobility hub shown in FIG. 1 comprises a plurality of local base stations 1, one or a plurality of means of transportation M having vehicle-mounted equipment (mobile terminals) capable of communicating with the local base stations 1, and the local base stations 1 and a network. computer group S connected via. This mobility hub is used in a Mobility as a Service (MaaS) communication system.

Transportation means M is used as a mobile service in MaaS, and examples thereof include various vehicles and railroads. The means of transportation M is equipped with an on-vehicle device as a mobile terminal that transmits information such as its position and type of vehicle, and receives usage requests and the like from users. Communication with this mobile terminal is performed via the local base station 1 .

The mobile terminal has a display device for providing information to the user of the means of transportation M and a voice output. Further, the mobile terminal has an input interface for the user to input usage requests and the like.

The computer group S is connected to a plurality of local base stations 1 via lines, and can perform cloud computing, for example. In the MaaS communication system, a mobility hub platform is configured by linking a mobile terminal of means of transportation M with a group of computers S.

A line between the local base station 1 and a mobile terminal of the means of transportation M (hereafter, a "mobile terminal of the means of transportation M" may be simply referred to as a "means of transportation M"), and a line between the local base station 1 and the computer group S The line is not particularly limited, and for example, a 5G line or a line conforming to IEEE802.11p standardized for ITS can be used.

A plurality of local base stations 1 are arranged so as to cover the communication area R, and the arrangement interval of the local base stations 1 (the distance to the closest local base station 1) is, for example, 0.5 km or more and 1.5 km or less. be. In addition, it is preferable that the communication area that can be covered by one local base station 1 is configured so that it partially overlaps with another local base station 1. It is preferably configured to allow. By covering the communication area R in this way, it is possible to prevent radio waves from becoming difficult to connect and improve the quality of communication.

The local base station of the present invention can be used for this local base station 1 . The local base station 1 can be suitably used in a MaaS communication system. The local base station 1 of the present invention will be described in detail below.

[Local base station]
The local base station 1 includes a power supply unit 2, an antenna unit 3, a communication unit 4, an environment sensor unit 5, and a control unit 6, as shown in FIG.

<Power supply>
The power supply unit 2 has a generator 21, a secondary battery 22, a supercapacitor 23, and a switch group 24, as shown in FIG. The power supply unit 2 supplies power to the communication unit 4 , the environment sensor unit 5 and the control unit 6 .

(Generator)
The generator 21 generates power from renewable energy. Renewable energy refers to energy that is constantly replenished and never depleted. Specific examples include sunlight, wind power, wave power, tidal power, flowing water, tides, geothermal heat, and the like.

Among these renewable energies, it is preferable to generate power using sunlight. That is, the generator 21 is preferably a solar power generator. If the generator 21 is a solar power generator, the amount of power generated can be accurately predicted based on the intensity of light received by the solar panel, the operating temperature of the solar battery, and changes in weather. The operational stability of the local base station 1 can be further improved. A case where the power generator 21 is a solar power generator will be described below as an example, but the present invention is not limited to a case where the power generator 21 is a solar power generator.

The power generator 21 preferably has a high power generation capacity. On the other hand, since the local base station 1 can operate without power supply from the system power supply, it is preferable that the local base station 1 can be easily relocated (has portability). Since the local base station 1 has portability, the local base station 1 can be used flexibly. From the viewpoint of this portability, it is preferable that the size and weight of the generator 21 are small, and its power generation capacity is restricted. From this point of view, the lower limit of the power generation capacity of the generator 21 is preferably 300 Wh, more preferably 500 Wh. On the other hand, the upper limit of the power generation capacity of the generator 21 is preferably 2000 Wh, more preferably 1500 Wh. If the power generation capacity of the power generator 21 is less than the above lower limit, there is a risk that the power that can be supplied from the power supply unit 2 will run short. Conversely, if the power generation capacity of the generator 21 exceeds the upper limit, the weight and size of the generator 21 become too large, and portability may not be ensured. It should be noted that the “power generation capacity of the generator” refers to the rated output of the generator.

From the viewpoint of portability, the upper limit of the volume of the generator 21 is preferably 8 m ³ and more preferably 4 m ³ . From the viewpoint of portability, the lower limit of the volume of the generator 21 is not particularly limited, and the ^smaller the better.

When the generator 21 is a solar power generator, the upper limit of the light-receiving area of the solar cell panel is preferably 10000 cm ² , more preferably 6400 cm ² . If the light-receiving area exceeds the upper limit, the portability may deteriorate. On the other hand, the lower limit of the light receiving area is not particularly limited from the viewpoint of portability, but from the viewpoint of power generation capacity, the light receiving area is usually set to 1000 cm ² or more.

(Secondary battery)
The secondary battery 22 can store the electric power generated by the generator 21 . The secondary battery 22 is a chemical battery that can be recharged and used repeatedly after being discharged. Since the power supply unit 2 includes the secondary battery 22, the surplus power generated by the generator 21 is stored, and the stored power can be used when the power from the generator 21 is reduced.

The secondary battery 22 is not particularly limited, but a known lead-acid battery, an alkaline storage battery such as nickel-cadmium or nickel-hydrogen, a lithium-ion battery, or the like can be used.

The amount of electricity stored in the secondary battery 22 is determined in consideration of the amount of power generated by the generator 21 , the power consumption required by the communication unit 4 , and the mass of the secondary battery 22 . In other words, the larger the amount of electricity generated by the generator 21 and the amount of power consumption required by the communication unit 4, the larger the storage amount of the secondary battery 22 is. The mass of the secondary battery 22 increases, and the equipment cost required for the secondary battery 22 increases. Therefore, the storage amount of the secondary battery 22 is determined in consideration of these balances.

(supercapacitor)
The supercapacitor 23 is a battery that can be charged and discharged faster than the secondary battery 22 . Since the secondary battery 22 has high impedance, it is difficult to store all the electric power generated by the generator 21 . In addition, when the power amplifier 42 is activated from an OFF state in which the power supply is cut off by the communication unit 4, which will be described later, for example, by normally-off control, the secondary battery 22 with high impedance is slow to start up. By controlling a group of switches 24 to be described later so that power is supplied from the supercapacitor 23, the system can be started up quickly. Since the power supply unit 2 includes the supercapacitor 23 in this way, it is possible to quickly adjust the storage of electric power in the power supply unit 2 and the supply of electric power to the communication unit 4 and the like.

The supercapacitor 23 is configured to store electric power generated by the generator 21 . Also, the supercapacitor 23 is configured to be charged from the secondary battery 22 .

Supercapacitor 23 is charged from generator 21 when generator 21 is producing a sufficient amount of electricity. On the other hand, when the power generation amount of the generator 21 is insufficient, the secondary battery 22 is charged. Since the power stored in the secondary battery 22 can be used when the power from the generator 21 drops in this way, the operation stability of the local base station 1 can be further improved.

In the local base station 1 , when the power supply from the generator 21 is insufficient, the secondary battery 22 and the supercapacitor 23 are used together to supply power to the communication unit 4 , the sensor unit 5 and the control unit 6 . When power is supplied from the supercapacitor 23, the secondary battery 22 is in an open state. Since the recovery effect of the secondary battery is thereby obtained, the life of the secondary battery 22 can be easily extended.

Supercapacitor 23 is preferably precharged. By precharging the supercapacitor 23 in this manner, the load current of the secondary battery 22 can be easily optimized, and the battery life of the secondary battery 22 can be extended by the recovery effect.

Charging control of the secondary battery 22 and the supercapacitor 23 is performed by the controller 6, which will be described later. This control is performed independently of other controls such as the communication unit 4 . Also, the amount of power generated by the generator 21 of the power supply unit 2, the amount of electricity stored in the secondary battery 22, and the amount of charge in the supercapacitor 23 are configured so that the control unit 6 can sequentially refer to them.

Note that the supercapacitor 23 can be replaced with a battery having equivalent performance. Examples of such batteries include lithium ion secondary batteries and lithium ion capacitors capable of high-speed charging and discharging.

(switch group)
The switch group 24 is composed of a plurality of switches, and is used for charging control of the secondary battery 22 and the supercapacitor 23 of the power supply unit 2 and power supply control to the communication unit 4, the environment sensor unit 5, and the control unit 6. . The switch group 24 is controlled by the controller 6 .

Specifically, the switch group 24 includes a first switch 24a that controls opening and closing between the generator 21 and the secondary battery 22, a second switch 24b that controls opening and closing between the generator 21 and the supercapacitor 23, and two switches. It has a third switch 24c that controls opening and closing between the secondary battery 22 and the supercapacitor 23, and a fourth switch 24d that selects one power supply from the generator 21, the secondary battery 22, and the supercapacitor 23.

By closing the first switch 24a, a charging circuit from the generator 21 to the secondary battery 22 is configured, and the secondary battery 22 is charged. By closing the second switch 24b (conducting state), a charging circuit from the generator 21 to the supercapacitor 23 is configured, and the supercapacitor 23 is charged. By closing the third switch 24c, a charging circuit from the secondary battery 22 to the supercapacitor 23 is configured, and the supercapacitor 23 is charged. In the closed state, the third switch 24c determines the charging direction according to the configuration for charging the secondary battery 22 from the supercapacitor 23 and the amount of charge in the secondary battery 22 and the amount of charge in the supercapacitor 23. can also be configured.

As the first switch 24a, the second switch 24b, and the third switch 24c, known opening/closing switches can be used, and the capacity thereof is appropriately determined according to the amount of current flowing through each switch.

The first switch 24a, the second switch 24b and the third switch 24c are, for example, exclusively controlled. That is, the first switch 24a, the second switch 24b, and the third switch 24c are controlled so that only one switch is closed at most.

Alternatively, two or more of the first switch 24a, the second switch 24b, and the third switch 24c can be closed at the same time, and charging can be performed through a plurality of paths at the same time. When the supply amount is excessive with respect to the charge amount, by using a plurality of paths at the same time, the generated power can be effectively utilized, and the operation stability of the local base station 1 can be further improved.

The fourth switch 24 d selects the power supply for supplying power to the communication unit 4 , the environment sensor unit 5 and the control unit 6 from the power generator 21 , secondary battery 22 and supercapacitor 23 .

As the fourth switch 24d, as shown in FIG. 3, for example, a known rotary switch that selects one power source from the generator 21, the secondary battery 22 and the supercapacitor 23 can be used. The configuration of 24d is not limited to this, and may be configured using a plurality of open/close switches. Note that the capacity of the fourth switch 24d is appropriately determined according to the amount of current that flows.

In FIG. 3, only one of the generator 21, the secondary battery 22, and the supercapacitor 23 is selected as the power supply source, but a configuration in which a plurality of power sources are selected is more preferable. In this case, a plurality of power supply sources are connected in parallel and used. By adopting a configuration in which a plurality of power supply sources can be selected in this manner, power can be supplied from both the generator 21 and the secondary battery 22, for example, when the power consumption is large. In other words, power management can be performed more dynamically according to the power consumption. Therefore, the operational stability of the local base station 1 can be further improved.

<Antenna part>
The antenna unit 3 is a connection starting point of a line between the local base station 1 and the means of transportation M and a line between the local base station 1 and the computer group S. FIG. The local base station 1 can transmit and receive information to and from the means of transportation M and the computer group S via radio.

Since a known antenna can be used as the antenna section 3, detailed description thereof will be omitted.

<Communication part>
The communication unit 4 operates by power supply from the power supply unit 2 and performs information communication via the antenna unit 3 . Information communication of the communication unit 4 is performed with respect to the means of transportation M and the computer group S. FIG. The communication unit 4 mainly includes a vehicle sensor 41, a power amplifier 42, a modem unit 43, a codec unit 44, a relay unit 45, a mode selection unit 46, and a control circuit 47, as shown in FIG. Prepare for.

(vehicle sensor)
The vehicle sensor 41 is a sensor that detects that the means of transportation M (vehicle) has entered the communication area of the local base station 1 and that it has left the communication area of the local base station 1 .

Specifically, the vehicle sensor 41 monitors the strength of the radio wave transmitted from the mobile terminal of the means of transportation M, and when detecting radio waves with a certain intensity or more, the corresponding means of transportation M enters the communication area. Conversely, when the strength of the radio wave drops below a certain level, it can be determined that the corresponding means of transportation M has left the communication area. It should be noted that the above "constant strength" is preferably set lower during exit than during entry in order to prevent frequent switching between entry and exit due to noise or the like.

(Power Amplifier)
A power amplifier 42 controls the output of the antenna section 3 .

The lower limit of the output of the power amplifier 42 is preferably 0.5W, more preferably 1W. On the other hand, the upper limit of the output of the power amplifier 42 is preferably 6W, more preferably 4W. If the output of the power amplifier 42 is less than the above lower limit, there is a possibility that radio waves may not sufficiently reach the communication range that the local base station 1 should cover. Conversely, if the output of the power amplifier 42 exceeds the upper limit, the power consumption becomes too large, and there is a risk that the local base station 1 will not operate sufficiently with power supply from the power supply unit 2 alone.

The output of the power amplifier 42 may be fixed, but preferably variably controlled by the control section 6, which will be described later.

(Modem part)
The modem unit 43 has a baseband unit that handles signals before modulation or after demodulation, and an RF unit that processes signals in the frequency band of electromagnetic waves that actually fly in the air. The baseband section can be configured with, for example, an LSI for digital signal processing, and the RF section can be configured with an analog IC that performs analog signal processing. Also, an AD converter and a DA converter, which serve as an interface between the baseband section and the RF section, can be incorporated in, for example, an LSI for digital signal processing.

The modulation/demodulation unit 43 may use a single modulation method, but is preferably configured to be able to select multiple types of modulation methods with different power consumptions. In this case, the selection of the plurality of modulation methods is controlled by the control unit 6, which will be described later, via the mode selection unit 46. FIG.

As the multiple types of modulation schemes, three types of 16QAM, QPSK, and BPSK may be used. These three types of modulation methods have a trade-off relationship between the transmission rate and the required power, and one of the plurality of types of modulation methods can be selected according to changes in the power supply capability of the power supply unit 2. Therefore, it is easy to balance the optimum communication speed and power consumption. It should be noted that it is also possible to select and use two of the three types of modulation schemes as the plurality of types of modulation schemes.

Further, four or more types of modulation schemes can be adopted as the plurality of types of modulation schemes. As these four types of modulation schemes, for example, 64QAM can be added to the three types of modulation schemes described above. If power conditions permit, communication performance can be improved by selecting 64QAM. When three or more modulation methods are employed, it is preferable to include the three types of 16QAM, QPSK, and BPSK, which facilitate the establishment of a trade-off relationship between the transmission rate and the required power.

(Codec part)
The encoder/decoder 44 encodes data to be transmitted via the antenna section 3 and decodes data to be received via the antenna section 3 . Specifically, the encoder/decoder 44 adds an error correction code to the data to be transmitted, and decodes the received data while performing error correction.

The codec/decoder 44 may use a single error correction method, but preferably uses a plurality of error correction methods with different code lengths. In this case, selection of a plurality of types of error correction methods is controlled by the control unit 6 (to be described later) via the mode selection unit 46 .

When using a plurality of types of error correction schemes and low power consumption is required, the strength of error correction should be lowered to shorten the code length. By shortening the code length, the same amount of information can be transmitted and received even if the reception speed is lowered. Therefore, power consumption can be reduced without lowering the information transmission speed.

(relay part)
The relay unit 45 serves as a relay for selecting connections between individual mobile terminals of means of transportation M and computer group S, and for connecting mobile terminals and computer group S in areas of other local base stations. fulfill the function of

(Mode selection part)
A mode selection unit 46 selects a protocol for the communication unit 4 . Mode selector 46 may include a two-way communication mode, a transmission mode, and a reception mode. These modes are selected through the control circuit 47 by the control section 6, which will be described later. Also, the mode selector 46 controls the modem 43 and codec 44 according to the protocol selected via the control circuit 47 .

In the two-way communication mode, the functions of the local base station 1 are maximized. On the other hand, the power consumption of the local base station 1 becomes maximum.

In the transmission mode, only the processing of receiving information such as the position and type of vehicle transmitted from the means of transportation M and transmitting the information to the computer group S is performed. This function enables the computer group S to select the most suitable means of transportation M. FIG. In this case, it is not possible to receive usage requests from users from the computer group S and transmit them to the means of transportation M through the local base station 1 . However, when means of transportation M is within the communication area of another local base station 1, transmission to means of transportation M can be performed using this other local base station 1 as an alternative base station.

In the reception mode, contrary to the transmission mode, only processing for receiving a request from the computer group S to the means of transportation M and transmitting the request to the means of transportation M is performed. This mode is for emergencies, and is used for the purpose of, for example, stopping the means of transportation M immediately in the event of a disaster to prevent the spread of damage.

The mode selection unit 46 may further include a local mode in which some or all of the two-way communication mode, transmission mode, and reception mode are limited depending on the remaining power level of the power supply unit. By having such a local mode, the power consumption of the communication unit 4 can be controlled with high precision, so that the operation stability of the local base station 1 can be further improved.

In addition, the mode selection unit 46 does not need to have all modes, and may have two types of two-way communication mode and transmission mode, or two types of two-way communication mode and reception mode. A two-way communication mode is preferably included to maximize the capabilities of station 1 .

The mode selector 46 may have other modes. Such other modes may include broadcast mode and priority reception mode. In other words, the mode selector 46 may further include a broadcast mode and a priority reception mode. Since the mode selector 46 further includes the broadcast mode and the priority reception mode in this way, it is possible to easily control the selection and concentration of functions under limited power.

The broadcast mode is a mode for simultaneous transmission to all mobile terminals. This broadcast mode can be used for the purpose of transmitting evacuation instructions and the like through communication terminals within the communication area R, for example, when a disaster occurs.

The priority reception mode is a mode for preferentially receiving information from a specific mobile terminal. This priority reception mode is a mode in which, for example, when an ambulance, an accident vehicle, or the like exists within the communication area R, information from these mobile terminals is preferentially received and processed.

(control circuit)
The control circuit 47 controls each function of the communication section 4 . That is, the control circuit 47 controls transmission/reception of information with the means of transportation M based on vehicle information from the vehicle sensor 41, and controls transmission/reception of information with the computer group S, according to instructions from the control unit 6, which will be described later. I do.

Specifically, the control circuit 47 controls the power amplifier 42 and the mode selection unit 46 in accordance with instructions such as the modulation/demodulation method and the output indicated by the control unit 6, which will be described later. Send and receive with group S.

In addition, the control circuit 47 is configured to be able to transmit to the control section 6 information on parameters that can be changed in the current communication service (parameter types and current numerical values).

The parameters that can be changed in the current communication service are, for example, usable modulation schemes when the modem unit 43 has a plurality of types of modulation schemes, and when the codec unit 44 has a plurality of error correction schemes with different code lengths. Refers to functional parameters that can be selected in the communication unit 4, such as code length.

(Power management of communication unit)
The communication unit 4 is preferably of a normally-off type. Since the power consumption of the communication unit 4 can be suppressed by making the communication unit 4 a normally-off type in this way, the operation stability of the local base station 1 can be further improved.

The normally-off type refers to a power management method in which, in principle, power is not supplied to functions that do not operate even when the power is turned on, and the power is immediately turned on as necessary. The control circuit 47 of the communication unit 4 is responsible for this normally-off type power supply management. Table 1 shows an example of normally-off control of each component of the communication unit 4 .

Each block of the communication unit 4 changes its operation mode between three modes of operation, standby, and off according to the communication service to be provided, thereby minimizing power consumption. Here, regarding the operation mode, "operation" refers to the operation of the corresponding function, "standby" refers to the state in which the operation is stopped while only the minimum necessary data is retained, and " "Off" refers to a state in which the power is cut off. In the "OFF" state, it is preferable to save the minimum necessary data using non-volatile memory, etc., so that the state can be immediately switched to the operating state. It may be a configuration that requires a process.

As shown in Table 1, the vehicle sensor 41 is required to detect the entry into the area of the means of transportation M that triggers the operation of the communication unit 4, and the means of transportation M that ends the operation of the communication unit 4. It is always kept in operation because it is necessary to detect exiting from the area of . For this reason, the vehicle sensor 41 "operates" even when the means of transportation M is not detected ("T0" in Table 1), and continues to operate even at other times, which will be described later. In the case of T0, all blocks are "OFF" because other functions are not required.

When the vehicle sensor 41 detects the means of transportation M (“T1” in Table 1), the next operation of the communication unit 4 is to receive information from the means of transportation M. FIG. Therefore, the baseband section and the RF section of the modem section 43 are in the "operating" state, and since the mode of the modem section 43 must also be determined, the mode selection section 46 is also in the "operating" state. On the other hand, since there is a high possibility that the information obtained from the means of transportation M will be transmitted to the computer group S after T1, the power amplifier 42 is placed in a "standby" state in order to secure the power required for transmission. At this point, information communication with the means of transportation M is performed, so the function to be set to the "operating" state is limited to only the functions necessary for information communication with the means of transportation M, and only information communication with the computer group S. Required functions are kept "off".

At the time when the information from the means of transportation M is received (“T2” in Table 1), the next operation of the communication unit 4 is to transmit and receive information to and from the mobile terminal of the means of transportation M. Therefore, in addition to T1, the power amplifier 42 is in the "operating" state. Also, since there is a high possibility that the transmission to the computer group S will be the next operation of the communication unit 4, the function related to the transmission to the computer group S is put in the "standby" state.

At the time of transmission to the computer group S ("T3" in Table 1), the functions required for information communication with the computer group S are in the "operating" state. On the other hand, since information transmission to the means of transportation M is not performed, the part that transmits information to the means of transportation M is put in a "standby" state. In Table 1, the power amplifier 42 and the RF section of the modulation/demodulation section 43 are set to "standby" in response to this, but if there is a section used for transmission to the computer group S, it will not function. there is

After the transmission to the computer group S is completed, the normally-off control should be returned to T0, for example.

<Environmental sensor part>
The environment sensor unit 5 acquires environment information. When the power generator 21 is a solar power generator, specifically, the environment sensor unit 5 has an illuminance meter 51, a weather gauge 52, and a thermometer 53, and these sensors determine the position of the local base station 1. Acquire surrounding environment information.

If the generator 21 is a solar power generator, the amount of power generated depends on the intensity of light received by the solar panel, the operating temperature of the solar cells, and changes in weather. Therefore, by configuring the environment sensor unit 5 to have the illuminance meter 51, the weather gauge 52, and the thermometer 53, it is possible to accurately predict the power supply capability from the power source, thereby further improving the operational stability of the local base station 1. can.

As the illuminance meter 51, the weather gauge 52, and the thermometer 53, well-known measuring instruments can be used, respectively, so detailed description thereof will be omitted. Information measured by the environment sensor unit 5 is also transmitted to the control unit 6 .

<Control section>
The control unit 6 controls operations of the communication unit 4 . Specifically, the control unit 6 controls the operation of the communication unit 4 so that the power consumption of the communication unit 4 is equal to or less than the power supply capability of the power supply unit 2 calculated based on the information from the environment sensor unit 5 .

The control unit 6 can be configured using a microcontroller 61, for example. The control unit 6 receives the amount of electricity stored in the secondary battery 22 and the amount of charge in the supercapacitor 23 of the power supply unit 2, and information measured by the environment sensor unit 5 (information on the illuminance meter 51, the weather gauge 52, and the thermometer 53). See The control unit 6 is configured to control the output of the power amplifier 42 of the communication unit 4, select the modulation method of the modem unit 43, and select the mode of the mode selection unit 46. FIG. By controlling these, the power consumption of the local base station 1 can be suppressed and the stable operation of the local base station 1 can be maintained. In addition, since an appropriate mode can be selected according to, for example, the presence or absence of a disaster and the power supply capacity of the power supply, maximum performance can be exhibited with limited power.

Also, the control unit 6 may have a database 62 as shown in FIG. The database 62 stores information and the like necessary for judgment for reducing the power consumption of the local base station 1 .

As information stored in the database 62, for example, as shown in FIG. 4, the relationship between the power amplifier transmission output and the communicable distance with the transmission rate as a parameter can be cited. Increasing the output of the power amplifier 42 extends the communicable distance. As shown in FIG. 4, this relationship varies depending on the transmission speed (adopted modulation method, etc.), so the transmission speed can be expressed as a parameter.

As another example, as shown in FIG. 5, the relationship between the power amplifier transmission output and the amount of data that can be processed per unit time can be mentioned, with the power generation amount as a parameter. If the power supplied is constant, increasing the output of the power amplifier 42 will reduce the amount of data that can be processed per unit time. Since the relationship varies depending on the amount of electric power supplied (power generation amount), the power generation amount can be expressed as a parameter.

For ease of understanding, the information is shown graphically in FIGS. 4 and 5, but the information is actually stored in the database 62 using, for example, a lookup table format or an equation of time function. The contents stored in the database 62 are not limited to those shown in FIGS. 4 and 5, and various information is selected and stored as necessary. Moreover, the information shown in FIGS. 4 and 5 is not essential, and one or both of these information may not be included in the database 62. FIG.

The microcontroller 61 is configured to be able to access this database 62 , and the information in the database 62 can be appropriately referred to by a program or the like that controls the microcontroller 61 to determine the control conditions for the operation of the communication section 4 .

<Control method of communication unit>
A specific operation example of the control unit 6 will be described below with reference to FIG. 6, but the control method by the control unit 6 is not limited to this.

The control method of the communication unit shown in FIG. 6 includes an environmental condition acquisition step (STEP 1), an electromotive force calculation step (STEP 2), a power storage amount acquisition step (STEP 3), a power storage amount reception step (STEP 4), and a switch control step. (STEP 5), a switch setting step (STEP 6), a settable parameter acquisition step (STEP 7), a settable parameter reception step (STEP 8), a power supply capacity prediction step (STEP 9), a parameter calculation step (STEP 10), It comprises a parameter transmission step (STEP11) and a parameter setting step (STEP12). The method of controlling the communication unit can be performed using the local base station 1 shown in FIG.

(Environmental condition acquisition step)
First, in an environmental condition acquisition step (STEP 1 ), the control unit 6 acquires measurement information from the environment sensor unit 5 . Specifically, information on the illuminance measured by the illuminance meter 51 , the temperature measured by the thermometer 52 , and the weather measured by the weather meter 52 is obtained from the environment sensor section 5 .

(Electromotive force calculation step)
Next, in an electromotive force calculation step (STEP 2 ), the control unit 6 estimates the power generation amount of the generator 21 from the information measured by the environment sensor unit 5 . The area S (cm ² ) of the solar cell panel of the photovoltaic generator, the illuminance L (lux) measured by the illuminometer 51, the power generation coefficient K (mW/cm ² /lux) of the photovoltaic element, and the sunshine duration H (hour), the amount of power generated by the generator 21 is C=S×L×K×H.

Now, if the size of the solar cell panel is 80 cm × 80 cm (= 6400 cm ² ), K = 1.464, the illuminance is 32,000 lux (approximately the illuminance during the daytime on cloudy days), and the sunshine duration is 8 hours, then C = It can be calculated as 240 (Wh). On the other hand, if the illuminance is 100,000 lux (illuminance in the daytime under fine weather), C=750 (Wh) can be calculated. Note that the above-mentioned coefficient K has temperature dependency, so it is corrected by the temperature T measured by the thermometer 52 . Also, the illuminance measured by the illuminance meter 51 is the illuminance at the time of measurement, not the average illuminance during the day. Therefore, based on the measurement result of the weather gauge 52, this illuminance should also be corrected.

(Stored power acquisition step and stored power reception step)
Next, in the stored electricity amount acquisition step (STEP 3), the control unit 6 receives the stored electricity amount acquired by the power supply unit 2 in the stored electricity amount receiving step (STEP 4).

Specifically, in the stored electricity amount acquisition step (STEP 3), the power supply unit 2 measures the amount of power generated by the generator 21 of the power supply unit 2, the amount of storage of the secondary battery 22 of the power supply unit 2, and the amount of charge of the supercapacitor 23. , the amount of power generated by the generator 21, the amount of electricity stored in the secondary battery 22, and the amount of charge in the supercapacitor 23 are transmitted to the control unit 6. FIG. The controller 6 receives the power generation amount of the generator 21, the power storage amount of the secondary battery 22, and the charge amount of the supercapacitor 23, which have been transmitted, in the power storage amount reception step (STEP 4).

The stored electricity amount acquisition step (STEP 3) may be executed in accordance with the request from the control unit 6 in the stored electricity amount reception step (STEP 4). Measured data may be transmitted to the control unit 6 asynchronously in accordance with a request from 6 .

(switch control step)
Next, in the switch control step (STEP 5), the control unit 6 receives the power generation amount of the generator 21, the storage amount of the secondary battery 22, and the charge amount of the supercapacitor 23 received in the storage amount reception step (STEP 4). , the switch configuration of the power supply unit 2 is determined.

For example, if the amount of power generated by the generator 21 is greater than or equal to a predetermined value and the amount of electricity stored in the secondary battery 22 is less than or equal to a predetermined value, the first switch 24a is closed to charge the secondary battery 22 from the generator 21. do. Further, if the amount of power generated by the generator 21 is equal to or greater than a predetermined value, the generator 21 is selected by the fourth switch 24d, and power is supplied from the generator 21 to the communication section 4, the sensor section 5, and the control section 6. FIG.

Also, if the power generation amount of the generator 21 is less than a predetermined value, power is supplied from the secondary battery 22 or the supercapacitor 23. For example, the secondary battery 22 and the supercapacitor 23 are alternately used at predetermined time intervals. It is preferable to control the fourth switch 24d so as to By controlling in this way, the recovery effect works on the secondary battery 22, and the life of the secondary battery 22 can be extended.

(switch setting step)
In the switch setting step (STEP6), the switch configuration information determined by the control unit 6 in the switch control step (STEP5) is received, and the power supply unit 2 sets the switch group 24 according to the information.

(Settable parameter acquisition step and settable parameter reception step)
Next, in the settable parameter receiving step (STEP8), the control section 6 receives the settable parameters obtained by the communication section 4 in the settable parameter obtaining step (STEP7).

Specifically, in a settable parameter acquisition step (STEP 7 ), the control circuit 47 of the communication unit 4 transmits information on parameters that can be changed in the current communication service to the control unit 6 . The control unit 6 receives the transmitted parameter information in the settable parameter reception step (STEP 8).

(Prediction of power supply capacity)
In the power supply capability prediction step (STEP 9 ), the control unit 6 predicts the amount of power that can be supplied from the power supply unit 2 . Specifically, the control unit 6 calculates the amount of electric power that can be used in one day from the total amount of power generated in one day, the amount of electricity stored in the secondary battery 22 of the power supply unit 2, and the amount of charge in the supercapacitor 23. Predictable.

(Parameter calculation step)
In the parameter calculation step (STEP 10 ), the control unit 6 calculates parameters for the functions of the communication unit 4 . Specifically, the control unit 6 selects the function of the communication unit 4 so that the communication unit 4 exhibits the maximum performance with power consumption equal to or less than the power amount predicted in the power supply capacity prediction step (STEP 9). Note that the parameters of the functions of the communication unit 4 that can be set are limited to the parameters received in the step of receiving settable parameters (STEP 8).

Here, the relationship between the performance of the communication unit 4 and power consumption will be described. If the transmission power is Pt, the reception sensitivity is Pr, and the wavelength is λ, the allowable propagation loss is α, the propagation attenuation constant, and the communication distance d is d=(λπ/4)×10 ^{((Pt−Pr)/α )} . Here, the reception sensitivity depends on the modulation method. When the coding rate is R=1/2 and the transmission speed is 24 Mbit/s in the 16QAM method, Rm=-74 dBm, and the transmission speed is 12 Mbit/s in the QPSK method. Then, Pm=-79 dBm, and if the transmission speed is 6 Mbit/s in the BPSK system, Pm=-82 dBm. For example, if the radio frequency is 3.7 MHz (λ=0.081 m) and α=2.5, the required output is
Case 1: Transmission speed 12 Mbit/s, communication distance d = 1 km, 4 W
Case 2: Transmission speed 12 Mbit/s, communication distance d = 0.8 km, 2 W
Case 3: Transmission speed 6 Mbit/s, communication distance d = 0.8 km, 1 W
etc., can be expected.

As described above, the amount of electric power required for the power amplifier 42 is determined when the transmission speed (modulation method) and communication distance are determined. Since it can be approximated that the power required for the power amplifier 42 is proportional to the power consumption of the entire communication unit 4 (for example, four times as a proportional coefficient), the power consumption of the entire communication unit 4 can be calculated from the amount of power required for the power amplifier 42. It can be estimated that Case 1 is 16 W, Case 2 is 8 W, and Case 3 is 4 W.

On the other hand, since the amount of power that can be used in one day is estimated as described above, one of Cases 1 to 3 can be selected within a range that does not exceed this amount of power. Here, for the sake of simplification, the selection is made from three cases, but for example, by storing information as shown in FIG. .

Furthermore, if the predicted value of the daily power generation amount is revised downward due to deterioration of the weather, etc., or if the predicted value of the power consumption is revised upward due to the communication volume exceeding the forecast, it is expected that the power supply unit 2 will run short of the power generation amount. be done. In such a case, the control unit 6 suspends some functions of the communication service, suppresses less urgent communication, and lengthens the communication interval to prolong the period in which the communication unit 4 is off. In this way, the power consumption of the communication unit 4 can be minimized. Also, for information transmission that does not require real-time performance, a method of temporarily storing data and batch transferring it when a certain amount of data is accumulated is also effective in reducing power consumption.

The control unit 6 may control the communication unit 4 algorithmically as described above, or may use artificial intelligence, so-called AI. For example, by using AI, for example, from the past data measured by the illuminance meter 51, the weather gauge 52, and the thermometer 53, the dependence of the change pattern, the seasonal dependence, etc. are learned, and the power generation amount is calculated with higher accuracy. make predictions.

Also, the control unit 6 selects one mode from the two-way communication mode, the transmission mode, and the reception mode of the mode selection unit 46 . By this selection, the functions of the communication unit 4 can be greatly restricted, and power consumption can be greatly reduced, or generated power can be used intensively only for a specific function. This control is mainly performed in an emergency.

(Parameter transmission step and parameter setting step)
In the parameter transmission step (STEP 11), the control unit 6 transmits to the communication unit 4 the setting parameters of the communication unit 4 calculated in the parameter calculation step (STEP 10). Then, in the parameter setting step (STEP 12 ), the setting parameters transmitted from the control unit 6 are set in the communication unit 4 . Accordingly, the communication unit 4 predicts the amount of power that can be supplied from the power supply unit 2, and controls the operation.

<Advantages>
Since the local base station 1 is powered by renewable energy, it can operate without power supply from the system power supply. The local base station 1 also predicts the amount of power that can be supplied from the power supply unit 2 from the environmental information acquired by the environment sensor unit 5 and controls the operation of the communication unit 4 . Therefore, even if the power supply capability of the power supply unit 2 is reduced due to changes in environmental conditions, it is possible to prevent the local base station 1 from not functioning. Therefore, the local base station 1 can stably operate even in a place where it is difficult to secure a system power supply.

[Other embodiments]
The above embodiments do not limit the configuration of the present invention. Therefore, in the above embodiment, the components of each part of the above embodiment can be omitted, replaced, or added based on the description of the present specification and common general technical knowledge, and all of them are interpreted as belonging to the scope of the present invention. should.

In the above embodiments, the case where the power supply unit has a secondary battery and a supercapacitor has been described, but these are not essential components, and some or all of them can be omitted. By omitting some or all of these, the weight of the local base station can be reduced, so portability can be improved. In addition, when omitting a part, it is preferable to omit the supercapacitor and use only the secondary battery from the viewpoint of the stability of the power supply. Also, switches can be omitted as appropriate depending on the omitted components.

In the above embodiment, the supercapacitor of the power supply unit has been described with a configuration that can be charged from the secondary battery.

Also, in the above embodiment, the switch for charging the secondary battery or supercapacitor from the generator can be omitted as needed. For example, the power generated by the generator is always used to charge the secondary battery, and the power stored in the secondary battery is used to charge the supercapacitor and to supply power to the communication unit, etc. The first switch for controlling charging to the secondary battery can be omitted.

In the above embodiment, the case where the power supply unit supplies power to the communication unit, the sensor unit, and the control unit has been described. Since the majority of the power consumption of the local base station occurs in the communication section, the same effect can be obtained as long as power supply to the communication section is performed from the power supply section. For example, as a configuration for supplying power to the sensor section and the control section, there may be mentioned a configuration in which a secondary battery is always used, a configuration in which a non-rechargeable battery is provided, and this non-rechargeable battery is used.

In the above embodiment, the case where the communication section has the mode selection section has been described, but the mode selection section is not an essential component and can be omitted. In the communication unit without the mode selection unit, the mode is fixed to the two-way communication mode.

In the above embodiment, the generator is a solar power generator, and the environment sensor section has an illuminance meter, a weather gauge, and a thermometer. However, the environment sensor section does not have to have all three. For example, a configuration having only an illuminance meter as an environment sensor or a configuration having an illuminance meter and a thermometer may be used.

Also, the environment sensor section may further include other sensors. Such other sensors may include, for example, location sensors (GPS). When the local base station is moved and used, the installation position can be confirmed by providing the GPS. In addition, since the installation positions of the local base stations can be known, for example, when mobile terminals are unevenly distributed in the area of a specific local base station, the information is shared among the local base stations and the areas covered by the local base stations are adjusted. can also Specifically, for example, by lowering the power amplifier output of local base stations where mobile terminals are unevenly distributed and increasing the power amplifier output of neighboring local base stations, the area range covered by each local base station can be expanded. It is possible to coordinate and alleviate uneven distribution of mobile terminals among local base stations.

In the above embodiment, the control unit is configured to control the output of the power amplifier of the communication unit, select the modulation scheme of the modulation/demodulation unit, and select the mode of the mode selection unit. As long as the power consumption is controlled, part or all of it can be omitted or another control method can be installed.

In the above embodiment, the local base station of the present invention is used in a MaaS communication system, but the application of the local base station of the present invention is not limited to the MaaS communication system. For example, it can be used to improve the communication environment in rural areas, to improve the communication environment in various parts of Asia and Africa where grid power is not available, or to install temporary local base stations in disaster areas in the event of a disaster, taking advantage of the portability of the local base station. can also

As explained above, the local base station of the present invention can stably operate even in a place where it is difficult to secure a system power supply.

1 Local Base Station 2 Power Supply Unit 21 Generator 22 Secondary Battery 23 Supercapacitor 24 Switch Group 24a First Switch 24b Second Switch 24c Third Switch 24d Fourth Switch 3 Antenna Unit 4 Communication Unit 41 Vehicle Sensor 42 Power Amplifier 43 Modem Unit 44 Coding/Decoding Unit 45 Relay Unit 46 Mode Selector 47 Control Circuit 5 Environment Sensor Unit 51 Luminometer 52 Weather Gauge 53 Thermometer 6 Control Unit 61 Microcontroller 62 Database M Means of Transportation R Communication Area S Computer Group

Claims (10)

a power supply;
an antenna section;
a communication unit that operates by power supply from the power supply unit and performs information communication with one or more mobile terminals via the antenna unit;
an environmental sensor unit that acquires environmental information;
and a control unit that controls the operation of the communication unit,
is portable and
The power supply unit has a generator that generates power from renewable energy,
The local base station, wherein the control unit controls the operation of the communication unit so that the power consumption of the communication unit is equal to or less than the power supply capability of the power supply unit calculated based on the information of the environment sensor unit. 2. The local base station according to claim 1, wherein the control section selectively controls a plurality of types of modulation schemes with different power consumptions . The environment sensor unit has an illuminometer, a weather gauge and a thermometer,
3. A local base station according to claim 1 or claim 2 , wherein said power generator is a solar power generator. The above power supply unit
A secondary battery and a supercapacitor capable of storing the power generated by the generator;
4. The local base station according to claim 1 , further comprising a switch that selects a power supply for supplying power to the communication unit from among the generator, the secondary battery, and the supercapacitor . 5. The local base station according to any one of claims 1 to 4, wherein said communication unit is of a normally-off type. The communication unit has a power amplifier that controls the output of the antenna unit,
6. The local base station according to any one of claims 1 to 5, wherein said controller controls the output of said power amplifier. The communication unit has a modulation/demodulation unit capable of selecting a plurality of types of modulation schemes with different power consumption,
7. The local base station according to any one of claims 1 to 6, wherein said control section selects a modulation scheme for said modulation/demodulation section. The communication unit has a mode selection unit including a two-way communication mode, a transmission mode and a reception mode,
8. The local base station according to any one of claims 1 to 7, wherein said controller selects a mode of said mode selector. 9. The local base station according to claim 8, wherein the mode selector further includes a broadcast mode for simultaneous transmission to all mobile terminals and a priority reception mode for preferentially receiving information from a specific mobile terminal. 10. The local base station according to any one of claims 1 to 9, which is used in a mobility as a service communication system.

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