Patent Description:
<CIT> describes a flight vehicle which forms a multi-cell on a ground by emitting beam towards the ground to provide a wireless communication service to user terminals in the multi-cell. <CIT> describes systems and methods implementing base station replacement in an ad hoc LTE system. In embodiments, an ad-hoc replacement cellular LTE base transceiver station connects to the back haul network and to a base transceiver station replacement computing facility. The base transceiver station replacement computing facility provisions the replacement cellular LTE base transceiver station with the same parameters as those of a first cellular LTE base transceiver station to which a plurality of mobile devices are connected, except for the cell identifier. The first cellular LTE base transceiver station reduces its transmit power while the replacement cellular LTE base transceiver station increases its transmit power, and each of the plurality of mobile devices are handed over from the first cellular LTE base transceiver station to the replacement cellular LTE base transceiver station when power levels and radio frequency (RF) propagation characteristics of the first and the replacement cellular transceiver stations determine appropriate handover conditions exist based on a predetermined algorithm, wherein the replacing of the cellular LTE base transceiver station is complete when all of the plurality of mobile transceiver devices are handed over to the replacement cellular LTE base transceiver station, and the first cellular LTE base transceiver station can removed from service. <CIT> describes methods of offloading user equipment communication traffic between communications drones. The methods may include receiving, at a candidate communication drone, a replacement request from a requesting communication drone. Radio frequency communication parameters may be set for the candidate communication drone to take over communications of the requesting communication drone. The RF communication parameters may be determined based on the replacement request and may distinguish the candidate communication drone from the requesting communication drone and at least one neighboring communication drone. The candidate communication drone may move toward a target position adjacent a position of the requesting communication drone without radiating RF communications for taking over communications of the requesting communication drone. In addition, the candidate communication drone may radiate RF communications using the set RF communication parameters to begin taking over communication services from the requesting communication drone upon arriving at the target position.

Embodiments of the invention are described in the dependent claims. According to an embodiment of the present invention, a control device is provided. The control device controls a flight vehicle which forms a multi-cell including a plurality of cells on a ground to provide a wireless communication service to user terminals in the multi-cell. The control device includes an output control unit which performs control such that in response to a state where a second flight vehicle which is to replace a first flight vehicle controlled by the control device has started forming a plurality of cells to be aligned with a position of each of the plurality of cells formed by the first flight vehicle, each of the plurality of cells formed by the second flight vehicle being in a same frequency band as that of each of the plurality of cells formed by the first flight vehicle, radio wave output of the plurality of cells of the first flight vehicle continuously falls. The output control unit individually controls a decreasing speed of the radio wave output with regard to each of the plurality of cells.

The control device includes a connection count acquisition unit which acquires a number of connections of the user terminals with regard to each of the plurality of cells of the first flight vehicle, in which the output control unit controls the decreasing speed of the radio wave output based on the number of connections of the user terminals with regard to each of the plurality of cells of the first flight vehicle. The output control unit may slow down the decreasing speed of the radio wave output as the number of connections of the user terminals is higher with regard to each of the plurality of cells of the first flight vehicle. The output control unit may set the decreasing speed of the radio wave output to be slower as the number of connections of the user terminals is higher with regard to each of the plurality of cells of the first flight vehicle. The output control unit may speed up the decreasing speed of the radio wave output as the number of connections of the user terminals is lower with regard to each of the plurality of cells of the first flight vehicle. The output control unit may set the decreasing speed of the radio wave output to be faster as the number of connections of the user terminals is lower with regard to each of the plurality of cells of the first flight vehicle. The control device includes an HO Out information acquisition unit which acquires HO Out information indicating a status of the user terminals handed over to be out with regard to each of the plurality of cells of the first flight vehicle, in which the output control unit may control the decreasing speed of the radio wave output based on the HO Out information with regard to each of the plurality of cells of the first flight vehicle. The HO Out information acquisition unit may acquire the HO Out information indicating a number of the user terminals handed over to be out per unit time with regard to each of the plurality of cells of the first flight vehicle. The output control unit may slow down the decreasing speed of the radio wave output as the number of the user terminals handed over to be out per unit time is higher with regard to each of the plurality of cells of the first flight vehicle. The output control unit may control the decreasing speed of the radio wave output based on the number of connections of the user terminals and the number of user terminals handed over to be out per unit time with regard to each of the plurality of cells of the first flight vehicle. When the number of connections of the user terminals is less than a predetermined threshold, the output control unit may set the decreasing speed of the radio wave output at a first decreasing speed, and when the number of connections of the user terminals is more than the predetermined threshold, the output control unit may set the decreasing speed of the radio wave output at a second decreasing speed that is slower than the first decreasing speed with regard to each of the plurality of cells of the first flight vehicle. Furthermore, after the first decreasing speed has been set, the output control unit may continue the comparison between the number of user terminals handed over to be out per unit time and the predetermined threshold, and when the number of user terminals handed over to be out per unit time is more than the threshold, the output control unit may further slow down the decreasing speed of the radio wave output. After the second decreasing speed has been set too, the output control unit may continue the comparison between the number of user terminals handed over to be out per unit time and the predetermined threshold, and when the number of user terminals handed over to be out per unit time is more than the threshold, the output control unit may further slow down the decreasing speed of the radio wave output. The control device may include an HO In information acquisition unit which acquires HO In information indicating a status of the user terminals handed over to be in with regard to each of the plurality of cells of the second flight vehicle, in which the output control unit may control the decreasing speed of the radio wave output based on the HO In information with regard to each of the plurality of cells of the first flight vehicle. The HO In information acquisition unit may acquire the HO In information indicating a number of the user terminals handed over to be in per unit time with regard to each of the plurality of cells of the second flight vehicle. The output control unit may slow down the decreasing speed of the radio wave output as the number of the user terminals handed over to be in per unit time to a cell in a corresponding position among the plurality of cells of the second flight vehicle is higher with regard to each of the plurality of cells of the first flight vehicle. The output control unit may control the decreasing speed of the radio wave output based on the number of connections of the user terminals and the number of user terminals handed over to be in per unit time with regard to each of the plurality of cells of the first flight vehicle. When the number of connections of the user terminals is less than the predetermined threshold, the output control unit may set the decreasing speed of the radio wave output at a first decreasing speed, and when the number of connections of the user terminals is more than the predetermined threshold, the output control unit may set the decreasing speed of the radio wave output at a second decreasing speed that is slower than the first decreasing speed with regard to each of the plurality of cells of the first flight vehicle. After the first decreasing speed has been set, the output control unit may continue the comparison between the number of user terminals handed over to be in per unit time to the cell in the corresponding position among the plurality of cells of the second flight vehicle and the predetermined threshold, and when the number of user terminals handed over to be in per unit time is more than the threshold, the output control unit may further slow down the decreasing speed of the radio wave output with regard to each of the plurality of cells of the first flight vehicle. After the second decreasing speed has been set too, the output control unit may continue the comparison between the number of user terminals handed over to be in per unit time to the cell in the corresponding position among the plurality of cells of the second flight vehicle and the predetermined threshold, and when the number of user terminals handed over to be in per unit time is more than the threshold, the output control unit may further slow down the decreasing speed of the radio wave output with regard to each of the plurality of cells of the first flight vehicle. The control device may be arranged on the ground, and the output control unit may individually control the decreasing speed of the radio wave output with regard to each of the plurality of cells by transmitting an instruction to the first flight vehicle. The control device may be mounted to the first flight vehicle.

According to an embodiment of the present invention, a program which causes a computer to function as the control device is provided.

According to an embodiment of the present invention, a system including the control device, the first flight vehicle, and the second flight vehicle is provided. After moving to a position corresponding to the first flight vehicle which forms the plurality of cells, the second flight vehicle may start to form the plurality of cells each of which is in a same frequency band as that of each of the plurality of cells of the first flight vehicle. The second flight vehicle may transmit, to the control device, HO In information indicating a status of the user terminals handed over to be in with regard to each of the plurality of cells.

According to an embodiment of the present invention, there is provided a control method executed by a control device which controls a flight vehicle having an antenna which forms a multi-cell including a plurality of cells on a ground to provide a wireless communication service to user terminals in the multi-cell. The control method includes controlling output by performing control such that in response to a state where a second flight vehicle which is to replace a first flight vehicle controlled by the control device has started forming a plurality of cells to be aligned with a position of each of the plurality of cells formed by the first flight vehicle, each of the plurality of cells formed by the second flight vehicle being in a same frequency band as that of each of the plurality of cells formed by the first flight vehicle, radio wave output of the plurality of cells of the first flight vehicle continuously falls. In the controlling the output, a decreasing speed of the radio wave output is individually controlled with regard to each of the plurality of cells.

According to an embodiment of the present invention, a control device is provided. The control device controls a replacement flight vehicle which is to replace an active flight vehicle having an antenna which forms a multi-cell including a plurality of cells on a ground to provide a wireless communication service to user terminals in the multi-cell. The control device includes a communication control unit which forms a plurality of cells to be aligned with a position of each of the plurality of cells formed by the active flight vehicle, each of the plurality of cells formed by the communication control unit being in a same frequency band as that of each of the plurality of cells formed by the active flight vehicle. The control device includes a notification unit which transmits, to the active flight vehicle, HO In information indicating a status of the user terminals handed over to be in with regard to each of the plurality of cells formed by the communication control unit.

Note that the summary clause does not necessarily describe all necessary features of the embodiments of the present invention.

A flight vehicle which forms cells on a ground while flying in a sky to provide a wireless communication service may require replacement with another flight vehicle for maintenance or the like. In a case where there are a flight vehicle A which has already configured a service area and a flight vehicle B arriving for the replacement, a method needs to be configured when the service based on the flight vehicle A is stopped, and the service is resumed by the flight vehicle B. In a system <NUM> according to the present embodiment, by adjusting transmission output of the flight vehicle A which has already configured the service area and the flight vehicle B arriving for the replacement, a number of handovers per unit time from cells of the flight vehicle A to cells of the flight vehicle B is controlled to aim for avoiding interference between the cells of the flight vehicle A and the cells of the flight vehicle B and for avoiding an overloaded state of the flight vehicle B.

Hereinafter, the present invention will be described through embodiments of the present invention, but the following embodiments do not limit the present invention according to claims. In addition, not all combinations of features described in the embodiment are essential to the solution of the invention.

<FIG> schematically illustrates an example of a system <NUM>. The system <NUM> may include a plurality of flight vehicles <NUM>. The system <NUM> may include a management server <NUM> which manages the plurality of flight vehicles <NUM>.

The flight vehicle <NUM> forms a multi-cell <NUM> including a plurality of cells <NUM> on a ground to provide a wireless communication service to user terminals <NUM> in the multi-cell <NUM>. The flight vehicle <NUM> may be an HAPS (high altitude platform station). The flight vehicle <NUM> may function as a stratospheric platform. For example, while flying in a stratosphere, the flight vehicle <NUM> forms a feeder link <NUM> with a gateway <NUM> on the ground, and also forms the multi-cell <NUM> by emitting beam <NUM> towards the ground.

The flight vehicle <NUM> may include a body section <NUM>, the wing section <NUM>, and a solar panel <NUM>. Electrical power generated by the solar panel <NUM> is stored in one or more batteries arranged in at least any of the body section <NUM> or the wing section <NUM>. The electrical power stored in the battery is used by each of the components included in the flight vehicle <NUM>.

A flight control device <NUM>, a communication control device <NUM>, and a control device <NUM> are arranged in the body section <NUM>. The flight control device <NUM> controls flight of the flight vehicle <NUM>. The communication control device <NUM> controls communication of the flight vehicle <NUM>.

The control device <NUM> controls the communication control device <NUM>. The control device <NUM> and the communication control device <NUM> may be integrated to each other. That is, the control device <NUM> may further function as the communication control device <NUM>. The control device <NUM> may control the flight control device <NUM>. The control device <NUM> and the flight control device <NUM> may be integrated to each other. That is, the control device <NUM> may further function as the flight control device <NUM>. The flight control device <NUM>, the communication control device <NUM>, and the control device <NUM> may be integrated to each other. That is, the control device <NUM> may further function as the flight control device <NUM> and the communication control device <NUM>.

The flight control device <NUM> controls the flight of the flight vehicle <NUM> controlling, for example, a rotation of a propeller, an angle of a flap or an elevator, or the like. The flight control device <NUM> may manage various types of sensors included in the flight vehicle <NUM>. Examples of the sensors include a positioning sensor such as a GPS (Global Positioning System) sensor, a gyro sensor, an acceleration sensor, a wind sensor, and the like. The flight control device <NUM> may manage a position, an attitude, a movement direction, a movement speed, and the like of the flight vehicle <NUM> by outputs of the various types of sensors.

The communication control device <NUM> may form the feeder link <NUM> with the gateway <NUM> by using an FL (Feeder Link) antenna. The communication control device <NUM> may access a network <NUM> via the gateway <NUM>.

The communication control device <NUM> may form the multi-cell <NUM> by emitting the beam <NUM> towards the ground by using an SL (Service Link) antenna. The multi-cell <NUM> is configured by a plurality of cells <NUM>. In <FIG>, a case has been exemplified where the number of cells <NUM> is seven but the number of cells <NUM> is not limited to this. The communication control device <NUM> may establish a service link with the user terminal <NUM> in the multi-cell <NUM>.

The communication control device <NUM> relays communication between the network <NUM> and the user terminal <NUM> via the feeder link <NUM> and the service link, for example. The communication control device <NUM> may provide the wireless communication service to the user terminal <NUM> by relaying the communication between the user terminal <NUM> and the network <NUM>.

The network <NUM> may include a core network managed by a telecommunications carrier. The core network may be compliant to an LTE (Long Term Evolution) communication method. That is, the core network may be an EPC (Evolved Packet Core). In this case, the communication control device <NUM> may function as eNB (eNodeB). The core network may be compliant to a <NUM> (5th Generation) communication method. That is, the core network may be a 5GC (5th Generation Core network). In this case, the communication control device <NUM> may function as gNB (gNodeB). The core network may be compliant to a <NUM> (3rd Generation) communication method, or may be compliant to a <NUM> (6th Generation) communication method and subsequent communication methods. The network <NUM> may include the Internet.

The user terminal <NUM> may be any communication terminal as long as the user terminal <NUM> can communicate with the flight vehicle <NUM>. For example, the user terminal <NUM> is a mobile phone such as a smartphone. The user terminal <NUM> may be a tablet terminal, a PC (Personal Computer), and the like. The user terminal <NUM> may also be a so-called IoT (Internet of Thing) device. The user terminal <NUM> may include anything that corresponds to a so-called IoE (Internet of Everything).

The flight vehicle <NUM> may circle in a sky above a target area in order to cover the target area on the ground by the multi-cell <NUM>. For example, while carrying out patrol flight in the sky above the target area in a predetermined flight path such as a circular, D-shaped, or <NUM>-shaped flight path, the flight vehicle <NUM> maintains the feeder link <NUM> with the gateway <NUM> by adjusting an orientation direction of the FL antenna, and maintains the coverage of the target area by the multi-cell <NUM> by adjusting an orientation direction of the SL antenna. Patrolling in a fixed flight path in the sky above the target area in this manner may be referred to as a fixed point flight.

The management server <NUM> manages the flight vehicle <NUM>. The management server <NUM> is arranged in the core network, for example. The management server <NUM> communications with the flight vehicle <NUM> via network <NUM> and the gateway <NUM>, for example. In addition, the management server <NUM> communications with the flight vehicle <NUM> via a satellite gateway <NUM> and a communications satellite <NUM>, for example. The management server <NUM> may control the flight vehicle <NUM> by transmitting an instruction.

The management server <NUM> may cause the flight vehicle <NUM> to perform the fixed point flight in the sky above the target area in order to cover the target area on the ground by the multi-cell <NUM>, for example. For each of a plurality of target areas, the management server <NUM> may cause the flight vehicle <NUM> to cover each of the plurality of target areas by performing the fixed point flight.

The flight vehicle <NUM> is required to land back to the ground for carrying out maintenance in a predetermined cycle such as once in every six months, for example. For example, the flight vehicle <NUM> is also required to land back to the ground when the battery deteriorates, an issue such as a failure occurs in various types of components such as the propeller, the flap, the elevator, and the solar panel <NUM>.

When the flight vehicle <NUM> is caused to simply land back, the provision of the wireless communication service in the target area on the ground covered by the flight vehicle <NUM> is terminated, and therefore it is desirable that the flight vehicle <NUM> is to be replaced with another flight vehicle <NUM>. When a first flight vehicle <NUM> which covers a certain target area is to be replaced with a second flight vehicle <NUM>, for example, it is conceivable that the first flight vehicle <NUM> is caused to stop the provision of the wireless communication service, and the second flight vehicle <NUM> is caused to head to a flight area where the first flight vehicle <NUM> has been flying to start the provision of the wireless communication service by the second flight vehicle <NUM>. However, in this case, at the time of transfer, a service interruption temporarily occurs, or a service quality temporarily deteriorates. In a case of a radio base station installed on the ground, a size of its coverage area is rather limited, and the temporary service quality deterioration may be acceptable. However, for example, in a case of the flight vehicle <NUM> which functions as the stratospheric platform, its coverage area becomes vast, and an impact may be extensive. The flight vehicle <NUM> according to the present embodiment has a function which contributes to appropriate performance of the replacement with another flight vehicle <NUM>.

<FIG> are explanatory diagrams for describing processing content at the time of the replacement. Herein, a case will be used as an example for the description where a flight vehicle A <NUM> which forms three cells including a cell <NUM>, a cell <NUM>, and a cell <NUM> on the ground is to be replaced with a flight vehicle B <NUM>. In the drawings, the user terminal <NUM> covered by the flight vehicle A <NUM> is represented by "A", and the user terminal <NUM> covered by the flight vehicle B <NUM> is represented by "B".

<FIG> illustrates a state in which the flight vehicle B <NUM> has moved to a position corresponding to the flight vehicle A <NUM> to replace the flight vehicle A <NUM>. In <FIG>, a case is exemplified where the flight vehicle B <NUM> is located at a position directly above the flight vehicle A <NUM> as the position corresponding to the flight vehicle A <NUM>, but is not limited to this. For example, when the flight vehicle A <NUM> is flying on a circular flight path, the position corresponding to the flight vehicle A <NUM> may be a position deviated by <NUM> degrees relative to the flight vehicle A <NUM> on the flight path. In addition to the above, the position corresponding to the flight vehicle A <NUM> may be any position for carrying out the replacement with the flight vehicle A <NUM>.

At a time point at which the flight vehicle B <NUM> has arrived at the position corresponding to the flight vehicle A <NUM>, the service is provided from the flight vehicle A <NUM>. Each of the cells of the flight vehicle A <NUM> is operated at radio wave output required to maintain the service. In this example, a case will be used as an example for the description where the radio wave output at this time is MAX, but is not limited to this. As long as the service can be maintained, the radio wave output may be lower than MAX. At this moment, the flight vehicle B <NUM> has not yet performed any output.

As illustrated in <FIG>, the flight vehicle B <NUM> transmits radio waves to configure service for areas that are same as target areas respectively covered by the cell <NUM>, the cell <NUM>, and the cell <NUM>. At this time, the flight vehicle B <NUM> uses a same frequency as that of the flight vehicle A <NUM>. That is, the flight vehicle B <NUM> forms a cell <NUM> in a same frequency as that of the cell <NUM>, forms a cell <NUM> in a same frequency as that of the cell <NUM>, and forms a cell <NUM> in a same frequency as that of the cell <NUM>. As a result, the cell <NUM> and the cell <NUM> cause interference to each other, the cell <NUM> and the cell <NUM> cause interference to each other, and the cell <NUM> and the cell <NUM> cause interference to each other.

As illustrated in <FIG> and <FIG>, in response to a state where the flight vehicle B <NUM> has started forming the cell <NUM>, the cell <NUM>, and the cell <NUM>, the flight vehicle A <NUM> decreases radio wave output. Herein, with regard to each of the cell <NUM>, the cell <NUM>, and the cell <NUM>, the flight vehicle A <NUM> sets a speed at which the radio wave output is decreased to be depended on a number of RRC Connected Users (which may be referred to as CU count) who have connection. As the CU count is higher, an output decreasing speed is set to be slower, and as the CU count is lower, the output decreasing speed is set to be faster.

By changing the output decreasing speed according to the CU count, the number of handovers per unit time from the cells of the flight vehicle A <NUM> to the cells of the flight vehicle B <NUM> can be controlled. Since the flight vehicle B <NUM> serves as an accepting side of the handover, when the number of handovers per unit time is higher, the communication control device <NUM> of the flight vehicle B <NUM> may be put into an overloaded state, and it may not be possible to perform communication. Thus, such control is carried out.

Note that as additional device for avoiding the overloaded state of the flight vehicle B <NUM>, the following two algorithms may be further introduced. According to a first algorithm, the cell of the flight vehicle A <NUM> checks a number of user terminals <NUM> handed over to be out from the flight vehicle A <NUM> in unit time, and increases or decreases the output decreasing speed depending on a magnitude of the number. The number of user terminals <NUM> handed over to be out from the flight vehicle A <NUM> in unit time can be autonomously determined by the flight vehicle A <NUM>.

According to a second algorithm, the cell of the flight vehicle B <NUM> checks a number of user terminals <NUM> handed over to be in to the flight vehicle B <NUM> in unit time, and determines whether a magnitude of the number may become an overload for the cell of the flight vehicle B <NUM>. For example, when it is determined that the magnitude of the number may become the overload, the flight vehicle B <NUM> transmits notification information for informing that effect to the flight vehicle A <NUM>, and in response to reception of the notification information, the flight vehicle A <NUM> slows down the output decreasing speed.

The flight vehicle B <NUM> transmits the notification information to the flight vehicle A <NUM> through the communications satellite <NUM>, for example. In addition, the flight vehicle B <NUM> transmits the notification information to the flight vehicle A <NUM> through the feeder link <NUM>, for example. As a specific example, the flight vehicle B <NUM> transmits the notification information to the flight vehicle A <NUM> via the gateway <NUM>. In addition, as a specific example, the flight vehicle B <NUM> transmits the notification information to the flight vehicle A <NUM> via the management server <NUM>.

When the flight vehicle B <NUM> can directly wirelessly communicate with the flight vehicle A <NUM>, the flight vehicle B <NUM> may directly transmit to the notification information to the flight vehicle A <NUM>. For example, the flight vehicle B <NUM> and the flight vehicle A <NUM> perform direct communication by forming a feeder link in the sky. When a network is configured by a plurality of flight vehicles <NUM> including the flight vehicle B <NUM> and the flight vehicle A <NUM> in the sky, the flight vehicle B <NUM> may transmit the notification information to the flight vehicle A <NUM> via the network in the sky.

<FIG> schematically illustrates an example of a flow of processing by the first flight vehicle <NUM> to be replaced. The processing may be started in response to a state where the replacing second flight vehicle <NUM> has started forming a plurality of cells <NUM> to be aligned with a position of each of a plurality of cells <NUM> formed by the first flight vehicle <NUM>, each of the plurality of cells <NUM> formed by the second flight vehicle <NUM> being in a same frequency band as that of each of the plurality of cells formed by the first flight vehicle <NUM>. The first flight vehicle <NUM> may perform processing illustrated in <FIG> with regard to each of the plurality of formed cells <NUM>.

In step (which may be abbreviated and referred to as S) <NUM>, the first flight vehicle <NUM> determines whether a number of RRC Connected Users is more than RRC Connected User Threshold or less. The number of RRC Connected Users may be a number of user terminals <NUM> put into RRC Connected state in the cell <NUM> that is set as a target. The RRC Connected User Threshold may be a number of RRC Connected Users which is set as a threshold at which the radio wave output of each of the cells <NUM> is significantly decreased or slightly decreased, and may be preset.

When it is determined that the number of RRC Connected Users is less than the RRC Connected User Threshold, the flow proceeds to S104, and when it is determined that the number of RRC Connected Users is more than the RRC Connected User Threshold, the flow proceeds to S106. In S104, the first flight vehicle <NUM> sets the output decreasing speed at Decreasing Tx Power Speed <NUM>. In S106, the first flight vehicle <NUM> sets the output decreasing speed at Decreasing Tx Power Speed <NUM>.

Tx Power may be output of a radio wave of a transmitting cell. Decreasing Tx Power Speed may be an amount of Tx Power to be decreased in unit time. The Decreasing Tx Power Speed <NUM> is faster than the Decreasing Tx Power Speed <NUM>. Thus, when a number of user terminals <NUM> present in the cell of the first flight vehicle <NUM> is high, by slowing down the output decreasing speed, generation of a situation where handovers of the user terminals <NUM> from the first flight vehicle <NUM> to the second flight vehicle <NUM> occur at once can be suppressed. On the other hand, thus, when the number of user terminals <NUM> present in the cell of the first flight vehicle <NUM> is low, by speeding up the output decreasing speed, a period of time during which the interference between the cell of the first flight vehicle <NUM> and the cell of the second flight vehicle <NUM> occurs can be shortened.

<FIG> schematically illustrates a flow of the processing by the first flight vehicle <NUM> when the first algorithm is implemented. Here, differences from <FIG> will be mainly described.

In S202, the first flight vehicle <NUM> determines whether the number of RRC Connected Users is more than the RRC Connected User Threshold or less. When it is determined that the number of RRC Connected Users is less than the RRC Connected User Threshold, the flow proceeds to S204, and when it is determined that the number of RRC Connected Users is more than the RRC Connected User Threshold, the flow proceeds to S212. In S204, the first flight vehicle <NUM> sets the output decreasing speed at the Decreasing Tx Power Speed <NUM>.

In S206, the first flight vehicle <NUM> determines whether HO Outgoing Speed is more than HO Outgoing Threshold or less. The HO Outgoing Speed may be a number of user terminals <NUM> handed over to be out from the cell in unit time. The HO Outgoing Threshold may be HO Outgoing Speed that is set as a threshold at which it is determined whether the Decreasing Tx Power Speed is to be increased or decreased, and may be preset.

When it is determined that the HO Outgoing Speed is more than the HO Outgoing Threshold, the flow proceeds to S208, and when it is determined that the HO Outgoing Speed is less than the HO Outgoing Threshold, the flow proceeds to S210. In S208, the first flight vehicle <NUM> slows down the Decreasing Tx Power Speed <NUM>. In S210, the first flight vehicle <NUM> determines whether the RRC Connected User is <NUM>. When it is determined that the RRC Connected User is not <NUM>, the flow returns to S206, and when it is determined that the RRC Connected User is <NUM>, the processing is ended.

In S212, the first flight vehicle <NUM> sets the output decreasing speed at the Decreasing Tx Power Speed <NUM>. In S214, the first flight vehicle <NUM> determines whether the HO Outgoing Speed is more than the HO Outgoing Threshold or less.

When it is determined that the HO Outgoing Speed is more than the HO Outgoing Threshold, the flow proceeds to S216, and when it is determined that the HO Outgoing Speed is less than the HO Outgoing Threshold, the flow proceeds to S218. In S216, the first flight vehicle <NUM> slows down the Decreasing Tx Power Speed <NUM>. In S218, the first flight vehicle <NUM> determines whether the RRC Connected User is <NUM>. When it is determined that RRC Connected User is not <NUM>, the processing is returned to S214, and when it is determined that the RRC Connected User is <NUM>, the processing is ended.

Thus, when the number of user terminals <NUM> handed over to be out from the cell <NUM> of the first flight vehicle <NUM> is high, that is, when the number of user terminals <NUM> handed over to be out from the cell <NUM> of the first flight vehicle <NUM> to the cell <NUM> of the second flight vehicle <NUM> is high, the output decreasing speed can be slowed down, and it is possible to suppress an increase in the load on the communication control device <NUM> of the second flight vehicle <NUM>.

<FIG> schematically illustrates a flow of the processing by the first flight vehicle <NUM> (referred to as the flight vehicle A) when the second algorithm is implemented. Here, differences from <FIG> will be mainly described.

In S302, the first flight vehicle <NUM> determines whether the number of RRC Connected Users is more than the RRC Connected User Threshold or less. When it is determined that the number of RRC Connected Users is less than the RRC Connected User Threshold, the flow proceeds to S304, and when it is determined that the number of RRC Connected Users is more than the RRC Connected User Threshold, the flow proceeds to S312. In S304, the first flight vehicle <NUM> sets the output decreasing speed at the Decreasing Tx Power Speed <NUM>.

In S306, the first flight vehicle <NUM> determines whether there is a notification indicating that HO Incoming Threshold is exceeded from the second flight vehicle <NUM> (referred to as the flight vehicle B). The second flight vehicle <NUM> regularly determines whether the HO Incoming Speed of the second flight vehicle <NUM> is more than the HO Incoming Threshold or less, and when it is determined that the HO Incoming Speed of the second flight vehicle <NUM> is more than the HO Incoming Threshold, the second flight vehicle <NUM> notifies the first flight vehicle <NUM> of that effect.

The HO Incoming Speed may be a number of user terminals <NUM> handed over to be in to the cell in unit time. The HO Incoming Threshold may be HO Incoming Speed that is set as a threshold at which it is determined whether the Decreasing Tx Power Speed is to be increased or decreased, and may be preset.

When it is determined that there is a notification, the flow proceeds to S308, and when it is determined that there is no notification, the flow proceeds to S310. In S318, the first flight vehicle <NUM> determines whether the RRC Connected User of the first flight vehicle <NUM> is <NUM>. When it is determined that the RRC Connected User is not <NUM>, the processing is returned to S306, and when it is determined that the RRC Connected User is <NUM>, the processing is ended.

In S312, the first flight vehicle <NUM> sets the output decreasing speed at the Decreasing Tx Power Speed <NUM>. In S314, the first flight vehicle <NUM> determines whether there is a notification indicating that the HO Incoming Threshold is exceeded from the second flight vehicle <NUM>.

When it is determined that there is a notification, the flow proceeds to S316, and when it is determined that there is no notification, the flow proceeds to S318. In S316, the first flight vehicle <NUM> determines whether the RRC Connected User of the first flight vehicle <NUM> is <NUM>. When it is determined that the RRC Connected User is not <NUM>, the flow returns to S314, and when it is determined that the RRC Connected User is <NUM>, the processing is ended.

Thus, when the number of user terminals <NUM> handed over to be out from the cell <NUM> of the first flight vehicle <NUM> to the cell <NUM> of the second flight vehicle <NUM> is high, the output decreasing speed can be slowed down, and it is possible to suppress an increase in the load on the communication control device <NUM> of the second flight vehicle <NUM>.

<FIG> schematically illustrates an example of a functional configuration of the control device <NUM>. The control device <NUM> includes a connection count acquisition unit <NUM>, an HO Out information acquisition unit <NUM>, an HO In information acquisition unit <NUM>, an output control unit <NUM>, and a notification unit <NUM>.

The connection count acquisition unit <NUM> acquires a number of connections of the user terminals <NUM> with regard to each of the plurality of cells <NUM> formed by the communication control device <NUM>. The connection count acquisition unit <NUM> may acquire the number of connections of the user terminals <NUM> for each of the plurality of cells <NUM> from the communication control device <NUM>.

The HO Out information acquisition unit <NUM> acquires HO Out information indicating a status of the user terminals <NUM> handed over to be out with regard to each of the plurality of cells <NUM> formed by the communication control device <NUM>. The HO Out information acquisition unit <NUM> may acquire the HO Out information of each of the plurality of cells <NUM> from the communication control device <NUM>. The HO Out information acquisition unit <NUM> may acquire the HO Out information indicating a number of user terminals <NUM> handed over to be out per unit time with regard to each of the plurality of cells <NUM> formed by the communication control device <NUM>.

The HO In information acquisition unit <NUM> acquires HO In information indicating a status of the user terminals <NUM> handed over to be in with regard to each of the plurality of cells <NUM> of another flight vehicle <NUM> (which may be referred to as a replacement flight vehicle) which replaces the flight vehicle <NUM> (which may be referred to as its own flight vehicle) to which the control device <NUM> is mounted. The HO In information acquisition unit <NUM> may acquire the HO In information indicating a number of user terminals <NUM> handed over to be in per unit time with regard to each of the plurality of cells <NUM> of the replacement flight vehicle.

The HO In information acquisition unit <NUM> may receive the HO In information from the replacement flight vehicle. The HO In information acquisition unit <NUM> receives the HO In information, for example, from the replacement flight vehicle through the communications satellite <NUM>. In addition, the HO In information acquisition unit <NUM> receives the HO In information, for example, from the replacement flight vehicle through the gateway <NUM>. In addition, the HO In information acquisition unit <NUM> receives the HO In information, for example, from the replacement flight vehicle via direct communication between the flight vehicle <NUM> and another flight vehicle <NUM>. In addition, the HO In information acquisition unit <NUM> receives the HO In information from the replacement flight vehicle, for example, via a network configured in the sky by the plurality of flight vehicles <NUM> including its own flight vehicle and the replacement flight vehicle.

The output control unit <NUM> controls radio wave output by the communication control device <NUM>. The output control unit <NUM> performs control such that in response to a state where the replacement flight vehicle has started forming a plurality of cells <NUM> to be aligned with a position of each of a plurality of cells <NUM> formed by the communication control device <NUM> of its own flight vehicle, each of the plurality of cells formed by the replacement flight vehicle being in a same frequency band as that of each of the plurality of cells <NUM> formed by the communication control device, the radio wave output of the plurality of cells <NUM> of its own flight vehicle continuously falls. The output control unit <NUM> may individually control the decreasing speed of the radio wave output with regard to each of the plurality of cells <NUM>.

For example, the output control unit <NUM> controls the decreasing speed of the radio wave output based on the number of connections acquired by the connection count acquisition unit <NUM> with regard to each of the plurality of cells <NUM> of its own flight vehicle. For example, the output control unit <NUM> slows down the decreasing speed of the radio wave output as the number of connections of the user terminals <NUM> is higher with regard to each of the plurality of cells <NUM> of its own flight vehicle. The output control unit <NUM> may set the decreasing speed of the radio wave output to be slower as the number of connections of the user terminals <NUM> is higher with regard to each of the plurality of cells <NUM> of its own flight vehicle.

In addition, for example, the output control unit <NUM> speeds up the decreasing speed of the radio wave output as the number of connections of the user terminals <NUM> is lower with regard to each of the plurality of cells <NUM> of its own flight vehicle. The output control unit <NUM> may set the decreasing speed of the radio wave output to be faster as the number of connections of the user terminals <NUM> is lower with regard to each of the plurality of cells <NUM> of its own flight vehicle.

The output control unit <NUM> may control the decreasing speed of the radio wave output based on the HO Out information acquired by the HO Out information acquisition unit <NUM> with regard to each of the plurality of cells <NUM> of its own flight vehicle. For example, the output control unit <NUM> slows down the decreasing speed of the radio wave output as the number of user terminals <NUM> handed over to be out per unit time is higher with regard to each of the plurality of cells <NUM> of its own flight vehicle.

The output control unit <NUM> may control the decreasing speed of the radio wave output based on the number of connections acquired by the connection count acquisition unit <NUM> and the HO Out information acquired by the HO Out information acquisition unit <NUM> with regard to each of the plurality of cells <NUM> of its own flight vehicle. For example, when the number of connections of the user terminals <NUM> is less than a predetermined threshold, the output control unit <NUM> sets the decreasing speed of the radio wave output at a first decreasing speed, and when the number of connections of the user terminals <NUM> is more than the predetermined threshold, the output control unit <NUM> sets the decreasing speed of the radio wave output at a second decreasing speed that is slower than the first decreasing speed with regard to each of the plurality of cells <NUM> of its own flight vehicle.

After the first decreasing speed has been set, the output control unit <NUM> then continues the comparison between the number of user terminals <NUM> handed over to be out per unit time and the predetermined threshold, and when the number of user terminals <NUM> handed over to be out per unit time is more than the threshold, the output control unit <NUM> further slows down the decreasing speed of the radio wave output. After the second decreasing speed has been set too, the output control unit <NUM> continues the comparison between the number of user terminals <NUM> handed over to be out per unit time and the predetermined threshold, and when the number of user terminals <NUM> handed over to be out per unit time is more than the threshold, the output control unit <NUM> further slows down the decreasing speed of the radio wave output.

The output control unit <NUM> may control the decreasing speed of the radio wave output based on the HO In information acquired by the HO In information acquisition unit <NUM> with regard to each of the plurality of cells <NUM> of its own flight vehicle. The output control unit <NUM> slows down the decreasing speed of the radio wave output as the number of user terminals <NUM> handed over to be in per unit time to a cell <NUM> in a corresponding position among the plurality of cells <NUM> of the replacement flight vehicle is higher, for example, with regard to each of the plurality of cells <NUM> of its own flight vehicle.

The output control unit <NUM> may control the decreasing speed of the radio wave output based on the number of connections acquired by the connection count acquisition unit <NUM> and the HO In information acquired by the HO In information acquisition unit <NUM> with regard to each of the plurality of cells <NUM> of its own flight vehicle. For example, when the number of connections of the user terminals <NUM> is less than the predetermined threshold, the output control unit <NUM> sets the decreasing speed of the radio wave output at the first decreasing speed, and when the number of connections of the user terminals <NUM> is more than the predetermined threshold, the output control unit <NUM> sets the decreasing speed of the radio wave output at the second decreasing speed that is slower than the first decreasing speed with regard to each of the plurality of cells <NUM> of its own flight vehicle.

After the first decreasing speed has been set, the output control unit <NUM> then continues the comparison between the number of user terminals <NUM> handed over to be in per unit time to the cell <NUM> in the corresponding position among the plurality of cells <NUM> of the replacement flight vehicle and the predetermined threshold, and when the number of user terminals <NUM> handed over to be in per unit time is more than the threshold, the output control unit <NUM> further slows down the decreasing speed of the radio wave output with regard to each of the plurality of cells <NUM> of its own flight vehicle. After the second decreasing speed has been set too, the output control unit <NUM> continues the comparison between the number of user terminals <NUM> handed over to be in per unit time to the cell <NUM> in the corresponding position among the plurality of cells <NUM> of the replacement flight vehicle and the predetermined threshold, and when the number of user terminals <NUM> handed over to be in per unit time is more than the threshold, the output control unit <NUM> further slows down the decreasing speed of the radio wave output with regard to each of the plurality of cells <NUM> of its own flight vehicle.

When its own flight vehicle functions as the replacement flight vehicle, the notification unit <NUM> transmits notification information to the flight vehicle <NUM> to be replaced (which may be referred to as an active flight vehicle). For example, the HO In information acquisition unit <NUM> acquires the HO In information indicating the number of the user terminals <NUM> handed over to be in with regard to each of the plurality of cells <NUM> of its own flight vehicle. The notification unit <NUM> then transmits notification information including the HO In information to the active flight vehicle. The notification unit <NUM> may transmit the notification information to the active flight vehicle via the communications satellite <NUM> or the gateway <NUM>. The notification unit <NUM> may also transmit the notification information to the active flight vehicle by way of direct communication between its own flight vehicle and the active flight vehicle or via a network in the sky.

According to the embodiment described with reference to <FIG>, a case has been described where the control device <NUM> mounted to the flight vehicle <NUM> serves as an entity to control the decreasing speed of the radio wave output with regard to each of the plurality of cells <NUM> formed by the communication control device <NUM>, but is not limited to this. The management server <NUM> may serve as an entity to perform the processing. The management server <NUM> may be an example of the control device.

<FIG> schematically illustrates an example of a functional configuration of the management server <NUM>. The management server <NUM> includes an information acquisition unit <NUM>, a flight vehicle management unit <NUM>, an output control unit <NUM>, and a notification unit <NUM>. Note that it is not necessarily imperative that the management server <NUM> includes all of these.

The information acquisition unit <NUM> includes a connection count acquisition unit <NUM>, an HO Out information acquisition unit <NUM>, and an HO In information acquisition unit <NUM>. The connection count acquisition unit <NUM> acquires the number of connections of the user terminals <NUM> with regard to each of the plurality of cells <NUM> formed by the active flight vehicle. The connection count acquisition unit <NUM> may receive the number of connections of the user terminals <NUM> in each of the plurality of cells <NUM> from the active flight vehicle.

The HO Out information acquisition unit <NUM> acquires the HO Out information indicating a status of the user terminals <NUM> handed over to be out with regard to each of the plurality of cells <NUM> formed by the active flight vehicle. The HO Out information acquisition unit <NUM> may acquire the HO Out information indicating the number of user terminals <NUM> handed over to be out per unit time with regard to each of the plurality of cells <NUM> formed by the active flight vehicle. The HO Out information acquisition unit <NUM> may receive the HO Out information of each of the plurality of cells <NUM> from the active flight vehicle. The management server <NUM> and the active flight vehicle may communicate via the feeder link <NUM>, or may communicate via the communications satellite <NUM>.

The HO In information acquisition unit <NUM> acquire the HO In information indicating a status of the user terminal <NUM> handed over to be in with regard to each of the plurality of cells <NUM> of the replacement flight vehicle. The HO In information acquisition unit <NUM> may acquire the HO In information indicating the number of user terminals <NUM> handed over to be in per unit time with regard to each of the plurality of cells <NUM> of the replacement flight vehicle. The HO In information acquisition unit <NUM> may receive the HO In information from the replacement flight vehicle. The management server <NUM> and the replacement flight vehicle may communicate via the feeder link <NUM>, or may communicate via the communications satellite <NUM>.

The flight vehicle management unit <NUM> manages a plurality of flight vehicles <NUM>. In order to form the multi-cell <NUM> in a target area on the ground, the flight vehicle management unit <NUM> may transmit, to each of the plurality of flight vehicles <NUM>, flight associated information such as a flight path to a fixed point flight area and a flight path in the fixed point flight area, and communication associated information such as a position and a range of the target area and configuration information related to wireless communication.

The flight vehicle management unit <NUM> instructs the active flight vehicle and the replacement flight vehicle to carry out replacement. The flight vehicle management unit <NUM> transmits, for example, to the replacement flight vehicle, a replacement instruction including information related to the active flight vehicle that is a replacement target, position information indicating a position corresponding to the active flight vehicle, and the like. The information related to the active flight vehicle may include a position and a range of each of the plurality of cells <NUM> formed by the active flight vehicle, and a frequency band in use. In response to reception of the replacement instruction, the replacement flight vehicle moves to the position corresponding to the active flight vehicle and starts to form the plurality of cells <NUM> to be aligned with a position of each of the plurality of cells <NUM> formed by the active flight vehicle, each of the plurality of cells formed by replacement flight vehicle being in a same frequency band as that of each of the plurality of cells <NUM> formed by the active flight vehicle.

The output control unit <NUM> controls radio wave output by the active flight vehicle. The output control unit <NUM> performs control such that in response to a state where the replacement flight vehicle has started forming the plurality of cells <NUM> to be aligned with the position of each of the plurality of cells <NUM> formed by the active flight vehicle, each of the plurality of cells formed by the replacement flight vehicle being in a same frequency band as that of each of the plurality of cells <NUM> formed by the active flight vehicle, the radio wave output of the plurality of cells <NUM> of the active flight vehicle continuously falls. The output control unit <NUM> may control the active flight vehicle by transmitting an instruction to the active flight vehicle. The output control unit <NUM> may individually control the decreasing speed of the radio wave output with regard to each of the plurality of cells <NUM>.

For example, the output control unit <NUM> controls the decreasing speed of the radio wave output based on the number of connections acquired by the connection count acquisition unit <NUM> with regard to each of the plurality of cells <NUM> of the active flight vehicle. For example, the output control unit <NUM> slows down the decreasing speed of the radio wave output as the number of connections of the user terminals <NUM> is higher with regard to each of the plurality of cells <NUM> of the active flight vehicle. The output control unit <NUM> may set the decreasing speed of the radio wave output to be slower as the number of connections of the user terminals <NUM> is higher with regard to each of the plurality of cells <NUM> of the active flight vehicle.

In addition, for example, the output control unit <NUM> speeds up the decreasing speed of the radio wave output as the number of connections of the user terminals <NUM> is lower with regard to each of the plurality of cells <NUM> of the active flight vehicle. The output control unit <NUM> may set the decreasing speed of the radio wave output to be faster as the number of connections of the user terminals <NUM> is lower with regard to each of the plurality of cells <NUM> of the active flight vehicle.

The output control unit <NUM> may control the decreasing speed of the radio wave output based on the HO Out information acquired by the HO Out information acquisition unit <NUM> with regard to each of the plurality of cells <NUM> of the active flight vehicle. For example, the output control unit <NUM> slows down the decreasing speed of the radio wave output as the number of user terminals <NUM> handed over to be out per unit time is higher with regard to each of the plurality of cells <NUM> of the active flight vehicle.

The output control unit <NUM> may control the decreasing speed of the radio wave output based on the number of connections acquired by the connection count acquisition unit <NUM> and the HO Out information acquired by the HO Out information acquisition unit <NUM> with regard to each of the plurality of cells <NUM> of the active flight vehicle. For example, when the number of connections of the user terminals <NUM> is less than the predetermined threshold, the output control unit <NUM> sets the decreasing speed of the radio wave output at a first decreasing speed, and when the number of connections of the user terminals <NUM> is more than the predetermined threshold, the output control unit <NUM> sets the decreasing speed of the radio wave output at a second decreasing speed that is slower than the first decreasing speed with regard to each of the plurality of cells <NUM> of the active flight vehicle.

The output control unit <NUM> may control the decreasing speed of the radio wave output based on the HO In information acquired by the HO In information acquisition unit <NUM> with regard to each of the plurality of cells <NUM> of the active flight vehicle. The output control unit <NUM> slows down the decreasing speed of the radio wave output as the number of user terminals <NUM> handed over to be in per unit time to the cell <NUM> in the corresponding position among the plurality of cells <NUM> of the replacement flight vehicle is higher, for example, with regard to each of the plurality of cells <NUM> of the active flight vehicle.

The output control unit <NUM> may control the decreasing speed of the radio wave output based on the number of connections acquired by the connection count acquisition unit <NUM> and the HO In information acquired by the HO In information acquisition unit <NUM> with regard to each of the plurality of cells <NUM> of the active flight vehicle. For example, when the number of connections of the user terminals <NUM> is less than the predetermined threshold, the output control unit <NUM> sets the decreasing speed of the radio wave output at the first decreasing speed, and when the number of connections of the user terminals <NUM> is more than the predetermined threshold, the output control unit <NUM> sets the decreasing speed of the radio wave output at the second decreasing speed that is slower than the first decreasing speed with regard to each of the plurality of cells <NUM> of the active flight vehicle.

After the first decreasing speed has been set, the output control unit <NUM> then continues the comparison between the number of user terminals <NUM> handed over to be in per unit time to the cell <NUM> in the corresponding position among the plurality of cells <NUM> of the replacement flight vehicle and the predetermined threshold, and when the number of user terminals <NUM> handed over to be in per unit time is more than the threshold, the output control unit <NUM> further slows down the decreasing speed of the radio wave output with regard to each of the plurality of cells <NUM> of the active flight vehicle. After the second decreasing speed has been set too, the output control unit <NUM> continues the comparison between the number of user terminals <NUM> handed over to be in per unit time to the cell <NUM> in the corresponding position among the plurality of cells <NUM> of the replacement flight vehicle and the predetermined threshold, and when the number of user terminals <NUM> handed over to be in per unit time is more than the threshold, the output control unit <NUM> further slows down the decreasing speed of the radio wave output with regard to each of the plurality of cells <NUM> of the active flight vehicle.

When notification information including the HO In information is received from the replacement flight vehicle, the notification unit <NUM> transmits the notification information to the active flight vehicle.

<FIG> schematically illustrates an example of hardware configuration of a computer <NUM> that functions as the control device <NUM> or the management server <NUM>. Programs installed in the computer <NUM> can cause the computer <NUM> to function as one or more "units" of the device according to the present embodiment or can cause the computer <NUM> to execute operations associated with the devices according to the present embodiment or the one or more "units", and/or can cause the computer <NUM> to execute a process according to the present embodiment or steps of the process. Such a program may be executed by a CPU <NUM> to cause the computer <NUM> to perform particular operations associated with some or all of the blocks in the flowcharts and block diagrams described in the specification.

The computer <NUM> according to the present embodiment includes the CPU <NUM>, a RAM <NUM>, and a graphics controller <NUM>, which are connected to each other via a host controller <NUM>. Also, the computer <NUM> includes input/output units such as a communication interface <NUM>, a storage device <NUM>, a DVD drive and an IC card drive, which are connected to the host controller <NUM> via an input/output controller <NUM>. The storage device <NUM> may be a hard disk drive, a solid-state drive, and the like. The computer <NUM> also includes a ROM <NUM> and a legacy input/output unit such as a keyboard, which are connected to the input/output controller <NUM> via an input/output chip <NUM>.

The CPU <NUM> operates according to the programs stored in the ROM <NUM> and the RAM <NUM>, thereby controlling each unit. The graphics controller <NUM> obtains image data which is generated by the CPU <NUM> in a frame buffer or the like provided in the RAM <NUM> or in itself so as to cause the image data to be displayed on a display device <NUM>.

The communication interface <NUM> communicates with other electronic devices via a network. The storage device <NUM> stores a program and data used by the CPU <NUM> in the computer <NUM>. The IC card drive reads programs and data from an IC card and/or writes programs and data into the IC card.

The ROM <NUM> stores therein a boot program or the like executed by the computer <NUM> at the time of activation, and/or a program depending on the hardware of the computer <NUM>. The input/output chip <NUM> may also connect various input/output units via a USB port, a parallel port, a serial port, a keyboard port, a mouse port, or the like to the input/output controller <NUM>.

A program is provided by a computer readable storage medium such as the DVD-ROM or the IC card. The program is read from the computer readable storage medium, installed into the storage device <NUM>, RAM <NUM>, or ROM <NUM>, which are also examples of a computer readable storage medium, and executed by the CPU <NUM>. Information processing written in these programs is read by the computer <NUM>, and provides cooperation between the programs and the various types of hardware resources described above. A device or method may be constituted by realizing the operation or processing of information in accordance with the usage of the computer <NUM>.

For example, in a case where a communication is performed between the computer <NUM> and an external device, the CPU <NUM> may execute a communication program loaded in the RAM <NUM> and instruct the communication interface <NUM> to perform communication processing based on a process written in the communication program. The communication interface <NUM>, under control of the CPU <NUM>, reads transmission data stored on a transmission buffer region provided in a recording medium such as the RAM <NUM>, the storage device <NUM>, the DVD-ROM, or the IC card, and transmits the read transmission data to a network or writes reception data received from a network to a reception buffer region or the like provided on the recording medium.

In addition, the CPU <NUM> may cause all or a necessary portion of a file or a database to be read into the RAM <NUM>, the file or the database having been stored in an external recording medium such as the storage device <NUM>, the DVD drive (DVD-ROM), the IC card, etc., and perform various types of processing on the data on the RAM <NUM>. Then, the CPU <NUM> may write the processed data back in the external recording medium.

Various types of information such as various types of programs, data, tables, and databases may be stored in a recording medium and subjected to information processing. The CPU <NUM> may execute, on the data read from the RAM <NUM>, various types of processing including various types of operations, information processing, conditional judgement, conditional branching, unconditional branching, information retrieval/replacement, or the like described throughout the present disclosure and specified by instruction sequences of the programs, to write the results back to the RAM <NUM>. In addition, the CPU <NUM> may retrieve information in a file, a database, or the like in the recording medium. For example, when a plurality of entries, each having an attribute value of a first attribute associated with an attribute value of a second attribute, are stored in the recording medium, the CPU <NUM> may search for an entry whose attribute value of the first attribute matches a designated condition, from among the plurality of entries, and read the attribute value of the second attribute stored in the entry, thereby obtaining the attribute value of the second attribute associated with the first attribute satisfying a predetermined condition.

The program or software module described above may be stored on the computer <NUM> or in a computer readable storage medium near the computer <NUM>. In addition, a recording medium such as a hard disk or a RAM provided in a server system connected to a dedicated communication network or the Internet can be used as the computer readable storage medium, thereby providing the program to the computer <NUM> via the network.

Blocks in flowcharts and block diagrams in the present embodiments may represent steps of processes in which operations are performed or "units" of devices responsible for performing operations. A particular step and "unit" may be implemented by dedicated circuitry, programmable circuitry supplied along with a computer readable instruction stored on a computer readable storage medium, and/or a processor supplied along with the computer readable instruction stored on the computer readable storage medium. The dedicated circuitry may include a digital and/or analog hardware circuit, or may include an integrated circuit (IC) and/or a discrete circuit. The programmable circuitry may include, for example, a reconfigurable hardware circuit including logical AND, logical OR, logical XOR, logical NAND, logical NOR, and other logical operations, and a flip-flop, a register, and a memory element, such as a field-programmable gate array (FPGA) and a programmable logic array (PLA).

The computer readable storage medium may include any tangible device capable of storing an instruction performed by an appropriate device, so that the computer readable storage medium having the instruction stored thereon constitutes a product including an instruction that may be performed in order to provide means for performing an operation specified by a flowchart or a block diagram. Examples of the computer readable storage medium may include an electronic storage medium, a magnetic storage medium, an optical storage medium, an electromagnetic storage medium, a semiconductor storage medium, and the like. More specific examples of computer readable storage media may include a floppy disk, a diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an electrically erasable programmable read-only memory (EEPROM), a static random access memory (SRAM), a compact disc read-only memory (CD-ROM), a digital versatile disk (DVD), a Blu-ray (registered trademark) disc, a memory stick, an integrated circuit card, etc..

The computer readable instruction may include an assembler instruction, an instruction-set-architecture (ISA) instruction, a machine instruction, a machine dependent instruction, a microcode, a firmware instruction, state-setting data, or either of source code or object code written in any combination of one or more programming languages including an object-oriented programming language such as Smalltalk (registered trademark), JAVA (registered trademark), and C++, and a conventional procedural programming language such as a "C" programming language or a similar programming language.

The computer readable instruction may be provided to a general purpose computer, a special purpose computer, or a processor or programmable circuitry of another programmable data processing device locally or via a local area network (LAN), a wide area network (WAN) such as the Internet or the like in order that the general purpose computer, the special purpose computer, or the processor or the programmable circuitry of the other programmable data processing device performs the computer readable instruction to provide means for performing operations specified by the flowchart or the block diagram. An example of the processor includes a computer processor, a processing unit, a microprocessor, a digital signal processor, a controller, a microcontroller, or the like.

According to the above described embodiment, the flight vehicle <NUM> has been used for the description as an example of the flight vehicle having the antenna which forms a wireless communication area on the ground by emitting the beam towards the ground to provide the wireless communication service to the user terminal in the wireless communication area, but is not limited to this. Examples of the flight vehicle include unmanned aerial vehicles such as a balloon, an airship, a plane, and a drone which can form the wireless communication area.

While the present invention has been described with the embodiments, the technical scope of the present invention is not limited to the above-described embodiments. It is apparent to persons skilled in the art that various alterations and improvements can be added to the above-described embodiments. It is also apparent from the scope of the claims that the embodiments added with such alterations or improvements can be included in the technical scope of the present invention.

The operations, procedures, steps, and stages of each process performed by an apparatus, system, program, and method shown in the claims, embodiments, or diagrams can be performed in any order as long as the order is not indicated by "prior to," "before," or the like and as long as the output from a previous process is not used in a later process. Even if the process flow is described using phrases such as "first" or "next" in the claims, embodiments, or diagrams, it does not necessarily mean that the process must be performed in this order.

Claim 1:
A control device (<NUM>) which controls a flight vehicle (<NUM>) which forms a multi-cell (<NUM>) including a plurality of cells (<NUM>) on a ground to provide a wireless communication service to user terminals (<NUM>) in the multi-cell (<NUM>), the control device (<NUM>) comprising:
an output control unit (<NUM>) which performs control such that in response to a state where a second flight vehicle (<NUM>) which is to replace a first flight vehicle (<NUM>) controlled by the control device (<NUM>) has started forming a plurality of cells (<NUM>) to be aligned with a position of each of the plurality of cells (<NUM>) formed by the first flight vehicle (<NUM>), each of the plurality of cells (<NUM>) formed by the second flight vehicle (<NUM>) being in a same frequency band as that of each of the plurality of cells (<NUM>) formed by the first flight vehicle (<NUM>), radio wave output of the plurality of cells (<NUM>) of the first flight vehicle (<NUM>) continuously falls, wherein
the output control unit (<NUM>) individually controls a decreasing speed of the radio wave output with regard to each of the plurality of cells (<NUM>), characterized in that the control device (<NUM>) further comprises
a connection count acquisition unit (<NUM>) which acquires a number of connections of the user terminals (<NUM>) with regard to each of the plurality of cells (<NUM>) of the first flight vehicle (<NUM>), wherein
the output control unit (<NUM>) controls the decreasing speed of the radio wave output based on the number of connections of the user terminals (<NUM>) with regard to each of the plurality of cells (<NUM>) of the first flight vehicle (<NUM>).