WO2020013176A1 - Single frequency network cell configuration using haps - Google Patents

Abstract

The present invention suppresses a deterioration in communication quality, which is caused by frequently-occurring handovers at the cell edges of a plurality of sector cells formed by a communication relay device that is movable in the air. The communication relay device, which wirelessly communicates with a terminal device, is provided with a relay communication station mounted in a floating body that is movable in the air by an autonomous control or a control from the outside. The relay communication station forms a plurality of sector cells so as to be able to wirelessly communicate with the terminal device. The plurality of sector cells include a plurality of single frequency network (SFN)-type sector cells in which identical data is transmitted in a state of being temporally synchronized at an identical frequency.

Description

Single frequency network cell configuration using HAPS

The present invention relates to a single frequency network (SFN) cell configuration using a communication relay device such as HAPS suitable for constructing a three-dimensional network for fifth generation communication.

Conventionally, a communication standard called LTE-AdvancedPro, which is an extension of LTE (Long Term Evolution) -Advanced (see Non-Patent Document 1) of 3GPP, which is a communication standard of a mobile communication system, is known (see Non-Patent Document 2). . In this LTE-AdvancedPro, specifications for providing communication to a device for recent IoT (Internet of Things) have been formulated. Furthermore, fifth-generation mobile devices that support simultaneous connection to a large number of terminal devices (also referred to as “UE (user device)”, “mobile station”, and “communication terminal”) such as devices for IoT and low delay. Communication is being studied (for example, see Non-Patent Document 3).

When a communication relay device for realizing a three-dimensional network in the fifth generation mobile communication or the like is movably arranged in the sky, the communication relay device may be located at a cell boundary of a plurality of cells formed toward the ground or the sea. There is a risk that communication quality will deteriorate or communication will be disconnected due to frequent handovers. In particular, when a plurality of cells formed by a communication relay device in the sky are formed along a vehicle moving route such as a high-speed rail or a highway on which a vehicle including a terminal device moves, the communication quality due to the frequent occurrence of the handover described above. Is likely to occur.

A communication relay device according to one embodiment of the present invention is a communication relay device that wirelessly communicates with a terminal device. The communication relay device is mounted on a levitating body that can move over the sky by autonomous control or external control, and wirelessly communicates with the terminal device. A relay communication station forming a wide area cell composed of a plurality of communicable sector cells, wherein the plurality of sector cells formed by the relay communication station are time-synchronized with each other by a same frequency in a downlink from the relay communication station. It includes a plurality of SFN (Single Frequency Network) sector cells that are continuously arranged and transmit the same data signal.
In the communication relay device, the plurality of sector cells of the SFN scheme may be formed along a movement route along which a vehicle including the terminal device moves.
Further, in the communication relay device, the plurality of sector cells formed by the relay communication station transmit different data signals at different frequencies in the downlink from the relay communication station and the plurality of SFN sector cells. And a plurality of MFN (multi-frequency network) type sector cells.

The communication relay device may further include a cell switching unit that selectively switches each of the plurality of sector cells formed by the relay communication station between the SFN sector cell and the MFN sector cell. In each of the plurality of sector cells, the cell switching unit uses the SFN scheme based on a PRB (physical resource block) usage rate of wireless communication between a terminal device located in the sector cell and the relay communication station. Switching between a sector cell and the MFN scheme sector cell may be performed. Further, the cell switching means switches between the SFN-based sector cell and the MFN-based sector cell in each of the plurality of sector cells based on a traffic situation of wireless communication with a terminal device located in the sector cell. May be performed.

A system according to another aspect of the present invention is a system including a plurality of communication relay devices that wirelessly communicate with a terminal device, wherein the plurality of communication relay devices respectively fly above the sky by autonomous control or external control. A relay communication station mounted on a movable floating body and forming a wide area cell including a plurality of sectors capable of wireless communication with the terminal device, wherein the plurality of sector cells formed by the relay communication stations of the plurality of communication relay devices are And a plurality of SFN (single frequency network) type sector cells which are continuously arranged and transmit signals of the same data in the downlink from the relay communication station in the same frequency and in time synchronization with each other.
In the system, the plurality of SFN sector cells may be continuously formed by a plurality of communication relay devices adjacent to each other among the plurality of communication relay devices.
In the system, the plurality of sector cells of the SFN scheme may be formed along a movement route along which a vehicle including a terminal device moves.
Further, in the system, the plurality of sector cells formed by the entire relay communication station of the plurality of communication relay devices are different from the plurality of SFN sector cells and the plurality of MFNs (multiple transmission units) transmitting different data at different frequencies. Frequency network) type sector cells.

The system may further include a cell switching unit that switches a plurality of sector cells formed by the relay communication stations of the plurality of communication relay apparatuses between the SFN sector cell and the MFN sector cell. In each of the plurality of sector cells, the cell switching unit uses the SFN scheme based on a PRB (physical resource block) usage rate of wireless communication between a terminal device located in the sector cell and the relay communication station. Switching between a sector cell and the MFN scheme sector cell may be performed. Further, the cell switching means switches between the SFN-based sector cell and the MFN-based sector cell in each of the plurality of sector cells based on a traffic situation of wireless communication with a terminal device located in the sector cell. May be performed.

The system further includes a remote control device for remotely controlling the plurality of communication relay devices, wherein the remote control device includes the SFN sector cell in at least one of the plurality of communication relay devices. And control information for controlling switching between the sector cell and the MFN scheme sector cell.

Still another remote control device of the present invention is a remote control device for remotely controlling the plurality of communication relay devices in the system, wherein at least one of the plurality of communication relay devices includes the SFN sector cell. And control information for controlling switching between the MFN-based sector cell and the MFN-based sector cell.

A method according to still another aspect of the present invention is directed to a communication relay device in which a relay communication station that performs wireless communication with a terminal device is mounted on a floating body that can move over the sky by autonomous control or external control. A method for controlling the formation of a wide area cell including a plurality of sector cells by the relay communication station, wherein the relay station transmits signals of the same data in the downlink from the relay communication station in time synchronization with each other at the same frequency. Forming the plurality of sector cells so as to include a plurality of SFN (single frequency network) type sector cells.
Further, a program according to yet another aspect of the present invention is a communication relay mounted on a floating body that can move over the sky by autonomous control or external control by a relay communication station that performs wireless communication with a terminal device. A program for causing a computer or a processor to execute control of formation of a wide area cell including a plurality of sector cells by the relay communication station in an apparatus, the program being in a state of being time-synchronized with each other by the same frequency in a downlink from the relay communication station. And a program code for forming the plurality of sector cells so as to include a plurality of continuously arranged SFN (single frequency network) type sector cells for transmitting the same data signal.

According to the present invention, it is possible to suppress the frequent occurrence of handover at the cell boundary of a plurality of sector cells formed by a communication relay device that can move in the sky and the deterioration of communication quality due to the increase in interference from neighboring cells.

FIG. 1 is a schematic configuration diagram illustrating an example of the overall configuration of a communication system that implements a three-dimensional network according to an embodiment of the present invention. FIG. 2 is a perspective view illustrating an example of the HAPS used in the communication system according to the embodiment. FIG. 3 is a side view illustrating another example of the HAPS used in the communication system according to the embodiment. FIG. 4 is an explanatory diagram illustrating an example of a wireless network formed in the sky with a plurality of HAPSs according to the embodiment. FIG. 5 is a schematic configuration diagram illustrating an example of the overall configuration of a communication system that implements a three-dimensional network according to still another embodiment. FIG. 6 is a block diagram illustrating a configuration example of the HAPS relay communication station according to the embodiment. FIG. 7 is a block diagram illustrating another configuration example of the HAPS relay communication station according to the embodiment. FIG. 8 is a block diagram showing still another configuration example of the HAPS relay communication station according to the embodiment. FIG. 9 is an explanatory diagram illustrating an example of a wide area cell including a plurality of sector cells formed by the HAPS according to the embodiment. FIG. 10 is an explanatory diagram illustrating an example of a plurality of wide area cells formed so as to be continuously arranged by a plurality of HAPSs according to the embodiment. FIG. 11 is an explanatory diagram illustrating an example of a plurality of sector cells formed by a plurality of HAPSs according to the embodiment so that a plurality of SFN cells are continuously arranged along a high-speed railway. FIG. 12 is an explanatory diagram showing another example of a plurality of sector cells formed so that a plurality of SFN cells are continuously arranged along a high-speed rail by a plurality of HAPSs according to the embodiment. FIG. 13A is an explanatory diagram illustrating an example of an arrangement of sector cells including SFN cells before the HAPS rotates. FIG. 13B is an explanatory diagram showing an example of an arrangement of sector cells including SFN cells after cell switching control when the HAPS rotates. FIG. 14 is a flowchart illustrating an example of the sector cell switching control in the HAPS according to the embodiment. FIG. 15 is a flowchart illustrating another example of the sector cell switching control in the HAPS according to the embodiment. FIG. 16 is a sequence diagram illustrating still another example of the sector cell switching control in the HAPS according to the embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram illustrating an example of the overall configuration of a communication system according to an embodiment of the present invention. The communication system according to the present embodiment is suitable for realizing a three-dimensional network of fifth-generation or subsequent fifth-generation mobile communication corresponding to simultaneous connection to a large number of terminal devices and reduction of delay. The mobile communication standard applicable to the communication system, the relay communication station, the base station, the repeater, and the terminal device disclosed in this specification is the fifth generation mobile communication standard, and the fifth and subsequent generations. Includes standards for the next generation of mobile communications.

As shown in FIG. 1, the communication system includes a plurality of high altitude platform stations (HAPS) (also referred to as “high altitude pseudo satellites”) 10 and 20 as a plurality of levitation type communication relay devices. The HAPSs 10 and 20 are located in an airspace at a predetermined altitude, and form three-dimensional sector cells (three-dimensional areas) 41 and 42 as indicated by hatched areas in the cell formation target airspace 40 at a predetermined altitude. The HAPS 10, 20 is a floating body (for example, a solar system) controlled by autonomous control or external control so as to float or fly in a high altitude air space (floating air space) 50 of 100 [km] or less from the ground or the sea surface. Plane, airship) equipped with a relay communication station.

The airspace 50 where the HAPSs 10 and 20 are located is, for example, a stratospheric airspace with an altitude of 11 km or more and 50 km or less. The airspace 50 may be an airspace having an altitude of 15 [km] or more and 25 [km] or less, where weather conditions are relatively stable, and may be an airspace of an altitude of approximately 20 [km]. Hrsl and Hrsu in the figure indicate the relative heights of the lower end and the upper end of the airspace 50 where the HAPSs 10, 20 are located, respectively, with respect to the ground (GL).

The cell formation target airspace 40 is a target airspace in which a three-dimensional cell is formed by one or more HAPSs in the communication system of the present embodiment. The cell formation target airspace 40 is located between the airspace 50 where the HAPSs 10 and 20 are located and a cell formation area near the ground covered by a base station (for example, an LTE eNodeB) 90 such as a conventional macrocell base station. This is an airspace within a range (for example, an altitude range of 50 [m] or more and 1000 [m] or less). Hcl and Hcu in the figure indicate the relative heights of the lower end and the upper end of the cell formation target airspace 40 with respect to the ground (GL), respectively.

The cell formation target airspace 40 in which the three-dimensional cell of the present embodiment is formed may be above the sea, river, or lake.

The relay communication stations of the HAPSs 10 and 20 form beams 100 and 200, respectively, for wireless communication with a terminal device as a mobile station toward the ground. The terminal device may be a communication terminal module incorporated in the drone 60 which is an aircraft such as a small helicopter capable of remote control, or a user device used by a user in the airplane 65. The areas where the beams 100 and 200 pass in the cell formation target airspace 40 are the three- dimensional cells 41 and 42. The plurality of beams 100 and 200 adjacent to each other in the cell formation target airspace 40 may partially overlap.

Each of the relay communication stations of the HAPSs 10 and 20 wirelessly communicates with, for example, a feeder station (also referred to as a “gateway station” or “GW station”) 70 as a relay station connected to a terrestrial (or marine) core network. It is a repeater slave unit that wirelessly communicates with a base station or a feeder station (repeater master unit) 70 as a relay station connected to a base station on the ground (or at sea). Each of the relay communication stations of the HAPSs 10 and 20 is connected to a core network of a mobile communication network 80 via a feeder station 70 installed on the ground or at sea. Communication between the HAPS 10, 20 and the feeder station 70 may be performed by wireless communication using radio waves such as microwaves, or may be performed by optical communication using laser light or the like.

Each of the HAPSs 10 and 20 may autonomously control its own levitating movement (flying) and processing at the relay communication station by executing a control program by a control unit including a computer or the like incorporated therein. For example, each of the HAPSs 10 and 20 acquires its own current position information (for example, GPS position information), position control information (for example, flight schedule information) stored in advance, position information of another HAPS located in the vicinity, and the like. Based on this information, levitation movement (flight) and processing at the relay communication station may be autonomously controlled.

The levitation movement (flying) of each of the HAPSs 10 and 20 and the processing at the relay communication station may be controlled by a remote control device 85 provided at a communication center or the like of the mobile communication network 80. The remote control device 85 can be composed of, for example, a computer device such as a PC or a server. In this case, the HAPSs 10 and 20 control communication terminal devices (for example, mobile communication modules) so that they can receive control information from the remote control device 85 and transmit various information such as monitoring information to the remote control device 85. May be incorporated, and terminal identification information (for example, an IP address, a telephone number, etc.) may be assigned so that the remote control device 85 can identify the terminal identification information. The MAC address of the communication interface may be used to identify the control communication terminal device. Each of the HAPSs 10 and 20 also collects information on the levitation movement (flight) of the HAPS itself or its surroundings, processing at the relay communication station, information on the state of the HAPSs 10 and 20, monitoring information such as observation data acquired by various sensors, and the like. Alternatively, the data may be transmitted to a predetermined transmission destination such as the remote control device 85. The control information may include target flight route information of the HAPS. The monitoring information includes the current position of the HAPS 10, 20, flight route history information, airspeed, ground speed and propulsion direction, the wind speed and direction of the airflow around the HAPS 10, 20, and the atmospheric pressure and temperature around the HAPS 10, 20. At least one piece of information may be included.

In the cell formation target airspace 40, there is a possibility that a region where the beams 100 and 200 of the HAPSs 10 and 20 do not pass (a region where the three- dimensional cells 41 and 42 are not formed) may occur. In order to supplement this area, as in the configuration example of FIG. 1, a radial beam 300 is formed upward from the ground side or the sea side to form a three-dimensional cell 43, and an ATG (Air @ To \ Ground) connection is formed. A base station (hereinafter, referred to as an “ATG station”) 30 may be provided.

By adjusting the positions of the HAPSs 10 and 20 and the divergence angles (beam widths) of the beams 100 and 200 without using the ATG station 30, the relay communication stations of the HAPSs 10 and 20 can move to the cell formation target airspace 40. The beams 100 and 200 may be formed so as to cover the entire upper end surface of the target cell formation space 40 so that the dimension cells are formed all over.

The three-dimensional cells formed by the HAPSs 10 and 20 may be formed so as to reach the ground or the sea surface so as to be able to communicate with a terminal device located on the ground or on the sea.

FIG. 2 is a perspective view illustrating an example of the HAPS 10 used in the communication system according to the embodiment.
The HAPS 10 of FIG. 2 is a solar plane type HAPS. The main wing 101 has both ends in the longitudinal direction extending upward, and a plurality of bus power propulsion devices are provided on one edge of the main wing 101 in the short direction. And a motor driven propeller 103. On the upper surface of the main wing portion 101, a photovoltaic panel (hereinafter, referred to as "solar panel") 102 as a photovoltaic power generation unit having a photovoltaic power generation function is provided. Further, pods 105 serving as a plurality of device housing portions for housing mission devices are connected to two longitudinally lower portions of the main wing portion 101 via plate-shaped connecting portions 104. Inside each pod 105, a relay communication station 110 as a mission device and a battery 106 are accommodated. Further, wheels 107 used for taking off and landing are provided on the lower surface side of each pod 105. The electric power generated by the solar panel 102 is stored in the battery 106, and the electric power supplied from the battery 106 drives the motor of the propeller 103 to rotate, so that the relay communication station 110 executes a wireless relay process.

The solar plane type HAPS 10 floats by lift, for example, by performing a circular flight, a “D” flight, or a “8” flight based on a predetermined target flight route, It can levitate so as to stay in a predetermined horizontal range at a predetermined altitude. When the propeller 103 is not driven to rotate, the solar plane type HAPS 10 can fly like a glider. For example, when the power of the battery 106 is excessive due to power generation of the solar panel 102 in the daytime or the like, the battery 106 rises to a high position, and when power cannot be generated in the solar panel 102 at night or the like, the power supply from the battery 106 to the motor is stopped and Can fly like.

The HAPS 10 also includes a three-dimensional directional optical antenna device 130 as a communication unit used for optical communication with another HAPS or an artificial satellite. In the example of FIG. 2, the optical antenna devices 130 are disposed at both ends in the longitudinal direction of the main wing portion 101, but the optical antenna devices 130 may be disposed at other locations of the HAPS 10. The communication unit used for optical communication with another HAPS or artificial satellite is not limited to the one that performs such optical communication, and may be a wireless communication using another method such as wireless communication using radio waves such as microwaves. Good.

FIG. 3 is a perspective view illustrating another example of the HAPS 20 used in the communication system according to the embodiment.
The HAPS 20 in FIG. 3 is an unmanned airship type HAPS, and has a large payload, so that a large-capacity battery can be mounted. The HAPS 20 includes an airship body 201 filled with a gas such as helium gas for buoyancy, a motor-driven propeller 202 as a propulsion device for a bus power system, and an equipment housing 203 for housing mission equipment. Prepare. The relay communication station 210 and the battery 204 are housed inside the device housing unit 203. The electric power supplied from the battery 204 drives the motor of the propeller 202 to rotate, and the relay relay station 210 executes a wireless relay process.

Note that a solar panel having a photovoltaic power generation function may be provided on the upper surface of the airship body 201, and the power generated by the solar panel may be stored in the battery 204.

The unmanned airship type HAPS 20 also includes the three-dimensional directional optical antenna device 230 as a communication unit used for optical communication with other HAPS and artificial satellites. In the example of FIG. 3, the optical antenna device 230 is disposed on the upper surface of the airship main body 201 and the lower surface of the device housing 203, but the optical antenna device 230 may be disposed on another portion of the HAPS 20. The communication unit used for optical communication with another HAPS or artificial satellite is not limited to the one that performs such optical communication, and performs wireless communication using another method such as wireless communication using radio waves such as microwaves. There may be.

FIG. 4 is an explanatory diagram illustrating an example of a wireless network formed above the plurality of HAPSs 10 and 20 according to the embodiment.
The plurality of HAPSs 10 and 20 are configured to enable communication between HAPSs by optical communication with each other in the sky, and form a wireless communication network with excellent robustness capable of stably realizing a three-dimensional network over a wide area. This wireless communication network can also function as an ad hoc network by dynamic routing according to various environments and various information. The wireless communication network can be formed to have various two-dimensional or three-dimensional topologies. For example, the wireless communication network may be a mesh-type wireless communication network as shown in FIG.

FIG. 5 is a schematic configuration diagram illustrating an example of the overall configuration of a communication system according to another embodiment. In FIG. 5, the same reference numerals are given to the same parts as those in FIG. 1 described above, and description thereof will be omitted.

In the embodiment of FIG. 5, communication between the HAPS 10 and the core network of the mobile communication network 80 is performed via the feeder station 70 and the low-orbit artificial satellite 72. In this case, communication between the artificial satellite 72 and the feeder station 70 may be performed by wireless communication using radio waves such as microwaves, or may be performed by optical communication using laser light or the like. Further, communication between the HAPS 10 and the artificial satellite 72 is performed by optical communication using laser light or the like.

FIG. 6 is a block diagram illustrating a configuration example of the relay communication stations 110 and 210 of the HAPSs 10 and 20 according to the embodiment.
The relay communication stations 110 and 210 in FIG. 5 are examples of repeater type relay communication stations. The relay communication stations 110 and 210 each include a 3D cell forming antenna unit 111, a transmission / reception unit 112, a feed antenna unit 113, a transmission / reception unit 114, a repeater unit 115, a monitoring control unit 116, and a power supply unit 117. Prepare. Furthermore, each of the relay communication stations 110 and 210 includes an optical communication unit 125 used for communication between HAPSs and the like, and a beam control unit 126.

The # 3D cell forming antenna unit 111 has an antenna that forms the radial beams 100 and 200 toward the cell forming target airspace 40, and forms three- dimensional cells 41 and 42 that can communicate with the terminal device. The transmission / reception unit 112 constitutes a first wireless communication unit together with the 3D cell forming antenna unit 111, has a duplexer (DUP: Duplexer), an amplifier, etc., and has a three-dimensional cell 41 via the 3D cell forming antenna unit 111. , 42, a wireless signal is transmitted to and received from a terminal device. The 3D cell forming antenna unit 111 and the transmitting / receiving unit 112 form a wide area cell including a plurality of sector cells, which will be described later, in a service link for communicating with the terminal device.

The feed antenna unit 113 has a directional antenna for wireless communication with the feeder station 70 on the ground or at sea. The transmission / reception unit 114 constitutes a second wireless communication unit together with the feed antenna unit 113, has a duplexer (DUP: Duplexer), an amplifier, etc., and transmits a wireless signal to the feeder station 70 via the feed antenna unit 113. , Or receives a wireless signal from the feeder station 70.

The repeater unit 115 relays a signal of the transmission / reception unit 112 transmitted / received to / from the terminal device and a signal of the transmission / reception unit 114 transmitted / received to / from the feeder station 70. The repeater unit 115 has an amplifier function of amplifying a signal to be relayed having a predetermined frequency to a predetermined level. The repeater unit 115 may have a frequency conversion function of converting the frequency of the signal to be relayed.

The monitoring control unit 116 is composed of, for example, a CPU and a memory, and monitors the operation processing status of each unit in the HAPSs 10 and 20 and controls each unit by executing a program incorporated in advance. In particular, the monitoring control unit 116 controls the motor drive unit 141 that drives the propellers 103 and 202 by executing the control program to move the HAPSs 10 and 20 to the target positions and to stay near the target positions. To control.

Further, the monitoring control unit 116 selectively converts each of a plurality of sector cells to be described later between an SFN (single frequency network) type sector cell (SFN cell) and an MFN type (multi frequency network) sector cell (normal cell). It also functions as cell switching means for switching to.

(4) The power supply unit 117 supplies the power output from the batteries 106 and 204 to each unit in the HAPSs 10 and 20. The power supply unit 117 may have a function of storing electric power generated by a solar panel or the like or electric power supplied from the outside in the batteries 106 and 204.

The optical communication unit 125 communicates with the other HAPSs 10 and 20 and the artificial satellite 72 via an optical communication medium such as a laser beam. This communication enables dynamic routing for dynamically relaying wireless communication between a terminal device such as the drone 60 and the mobile communication network 80, and allows one HAPS to back up when one of the HAPSs fails. By performing the wireless relay, the robustness of the mobile communication system can be improved.

The beam control unit 126 controls the direction and intensity of a beam such as a laser beam used for inter-HAPS communication and communication with the artificial satellite 72, and controls the relative position with respect to another HAPS (relay communication station) in the vicinity. In response to the change, control is performed such that another HAPS (relay communication station) that performs communication using a light beam such as a laser beam is switched. This control may be performed based on, for example, the position and orientation of the HAPS itself, the position of the surrounding HAPS, and the like. The information on the position and orientation of the HAPS itself is obtained based on the output of a GPS receiver, a gyro sensor, an acceleration sensor, and the like incorporated in the HAPS, and the information on the position of the surrounding HAPS is obtained from a remote control provided on the mobile communication network 80. It may be obtained from the control device 85 or a server 86 such as a HAPS management server or an application server.

FIG. 7 is a block diagram illustrating another configuration example of the relay communication stations 110 and 210 of the HAPSs 10 and 20 according to the embodiment.
The relay communication stations 110 and 210 in FIG. 7 are examples of base station type relay communication stations.
In FIG. 7, the same components as those in FIG. 6 are denoted by the same reference numerals, and description thereof will be omitted. Each of the relay communication stations 110 and 210 in FIG. 7 further includes a modem unit 118 and includes a base station processing unit 119 instead of the repeater unit 115. Further, the relay communication stations 110 and 210 each include an optical communication unit 125 and a beam control unit 126.

The modem unit 118 performs, for example, a demodulation process and a decoding process on a reception signal received from the feeder station 70 via the feed antenna unit 113 and the transmission / reception unit 114, and outputs a data signal output to the base station processing unit 119 side. Generate Further, the modem unit 118 performs an encoding process and a modulation process on the data signal received from the base station processing unit 119 side, and transmits the data signal to the feeder station 70 via the feed antenna unit 113 and the transmission / reception unit 114. Generate a signal.

The base station processing unit 119 has, for example, a function as an e-NodeB that performs baseband processing based on a method compliant with the LTE / LTE-Advanced standard. The base station processing unit 119 may perform processing by a method conforming to a standard for future mobile communication such as the fifth generation.

The base station processing unit 119 performs, for example, demodulation processing and decoding processing on a reception signal received from the terminal device located in the three- dimensional cells 41 and 42 via the 3D cell forming antenna unit 111 and the transmission / reception unit 112. , And generates a data signal to be output to the modem unit 118 side. Further, the base station processing unit 119 performs an encoding process and a modulation process on the data signal received from the modem unit 118 side, and performs three- dimensional cells 41 and 42 via the 3D cell forming antenna unit 111 and the transmitting / receiving unit 112. A transmission signal to be transmitted to the terminal device is generated.

FIG. 8 is a block diagram showing still another configuration example of the relay communication stations 110 and 210 of the HAPSs 10 and 20 according to the embodiment.
The relay communication stations 110 and 210 in FIG. 8 are examples of a high-performance base station type relay communication station having an edge computing function. In FIG. 8, the same components as those in FIGS. 6 and 7 are denoted by the same reference numerals, and description thereof will be omitted. Each of the relay communication stations 110 and 210 in FIG. 8 further includes an edge computing unit 120 in addition to the components in FIG.

The edge computing unit 120 is composed of, for example, a small computer, and can execute various types of information processing related to wireless relay in the relay communication stations 110 and 210 of the HAPSs 10 and 20 by executing a program incorporated in advance. it can.

For example, the edge computing unit 120 determines the transmission destination of the data signal based on the data signal received from the terminal device located in the three- dimensional cell 41, 42, and based on the determination result, determines the relay destination of the communication. Is executed. More specifically, when the transmission destination of the data signal output from base station processing section 119 is a terminal device located in its own three- dimensional cell 41 or 42, the data signal is not passed to modem section 118. Then, it returns to the base station processing unit 119 to transmit to the terminal device of the transmission destination located in its own three- dimensional cell 41, 42. On the other hand, when the transmission destination of the data signal output from base station processing section 119 is a terminal device located in a cell other than its own three- dimensional cell 41 or 42, the data signal is passed to modem section 118. The data is transmitted to the feeder station 70 and transmitted to the destination terminal device located in another cell of the destination via the mobile communication network 80.

The edge computing unit 120 may execute a process of analyzing information received from a large number of terminal devices located in the three- dimensional cells 41 and 42. This analysis result is transmitted to a large number of terminal devices located in the three- dimensional cells 41 and 42, a remote control device 85 provided in the mobile communication network 80, or a HAPS management server or application server (application server) as a remote control device. Server 86 or the like.

The uplink and downlink duplex schemes of wireless communication with the terminal device via the relay communication stations 110 and 210 are not limited to a specific scheme. For example, a time division duplex (Time / Division / Duplex: TDD) scheme may be used. Alternatively, frequency division duplex (Frequency Division Duplex: FDD) may be used. In addition, the access method of wireless communication with the terminal device via the relay communication stations 110 and 210 is not limited to a specific method. For example, an FDMA (Frequency Division Multiple Multiple Access) method, a TDMA (Time Division Multiple Multiple Access) method, It may be a CDMA (Code Division Multiple Access) system or an OFDMA (Orthogonal Frequency Division Multiple Access). In addition, the wireless communication has functions such as diversity coding, transmission beamforming, and space division multiplexing (SDM), and simultaneously uses a plurality of antennas for both transmission and reception to achieve per unit frequency. MIMO (Multi-Input and Multi-Output) technology that can increase the transmission capacity of the MPU may be used. The MIMO technology may be an SU-MIMO (Single-User @ MIMO) technology in which one base station transmits a plurality of signals at the same time and the same frequency as one terminal device, or one base station may transmit a plurality of signals. MU-MIMO (Multi-User @ MIMO) technology in which signals are transmitted to different terminal devices at the same time and the same frequency or a plurality of different base stations transmit signals to one terminal device at the same time and the same frequency may be used. .

Hereinafter, a case will be described in which a communication relay device that wirelessly communicates with a terminal device is a solar plane type HAPS 10 having a relay communication station 110. In the following embodiment, an unmanned airship type HAPS 20 having a relay communication station 210 will be described. The present invention can be similarly applied to other communication relay devices that can move over the sky.

FIG. 9 is an explanatory diagram illustrating an example of a service link wide area cell 100A including a plurality of sector cells 401 to 407 formed by the HAPS 10 according to the embodiment. Although FIG. 9 shows an example in which one wide area cell 100A in the service link is composed of seven sector cells, the number of sector cells constituting the wide area cell 100A may be two to six, or eight. The number may be more than one.

FIG. 10 is an explanatory diagram showing an example of a plurality of wide area cells formed so as to be continuously arranged by a plurality of HAPSs according to the embodiment. Although FIG. 10 shows only the footprint area of the wide area cell 100A on the ground or the sea and the sector cells constituting the same, a cone or a pyramid is formed between the footprint area and the HAPS 10. A three-dimensional wide area cell and a sector cell having a three-dimensional shape such as those described above are formed (the same applies to FIGS. 11 to 13).

In the example of FIG. 10, 14 HAPSs 10 are arranged above the Japanese archipelago, so that 14 wide area cells 100 </ b> A are continuously arranged above the Japanese archipelago, and the mobile communication service via the HAPS 10 above the entire Japanese archipelago is provided. Can be provided. The bold line in the Japanese archipelago in the figure indicates the moving route (Shinkansen route) 400 of the Shinkansen that is a high-speed railway.

When a plurality of HAPSs 10 are movably arranged in the sky as in the present embodiment, the communication relay device may be used at the cell boundary between the wide area cells of the plurality of wide area cells 100A formed toward the ground or the sea or between the sector cells. There is a risk that communication quality will deteriorate or communication will be disconnected due to frequent handovers. In particular, when a plurality of sector cells formed by the HAPS 10 in the sky are formed along a vehicle movement route such as a high-speed railway such as the Shinkansen route 400 or a highway, communication quality is deteriorated due to the frequent occurrence of the handover. It's easy to do.

Therefore, the plurality of sector cells formed by the HAPS 10 of the present embodiment are a plurality of SFNs (single frequency networks) that are continuously arranged and transmit signals of the same data in the downlink from the HAPS 10 in the same frequency and in time synchronization with each other. System sector cells (hereinafter also referred to as “SFN cells”). Since a plurality of SFN cells arranged continuously are time-synchronized with each other, downlink signals transmitted by, for example, orthogonal frequency division multiplexing (OFDM) transmission are the same among sector cells and are treated as a single cell. No handover between sector cells occurs. Further, in a cell boundary area between SFN cells, a combined gain is obtained by receiving a transmission signal of the same data synchronized in time, so that interference in the cell boundary area is eliminated and SINR (required signal versus interference) is obtained. (Noise power ratio) is increased, so that a decrease in communication quality can be prevented.

FIG. 11 is an explanatory diagram showing another example of a plurality of sector cells formed by a plurality of HAPSs according to the embodiment so that a plurality of SFN cells are continuously arranged along a high-speed railway (Shinkansen route). In the example of FIG. 11, the hatched SFN cells in the figure are formed along the Shinkansen route 400 of the high-speed railway in which the terminal device moves at high speed together with the vehicle, and the Shinkansen route 400 is covered by the SFN cells. In addition, it is possible to prevent frequent handovers caused by the terminal device moving at high speed together with a high-speed rail vehicle.

Further, in the example of FIG. 11, not all of the plurality of sector cells formed by each HAPS 10 are SFN cells, but the sector cells located along the Shinkansen route 400 where handovers are likely to occur frequently (the hatched cells in FIG. (Sector cells) only are SFN cells. The other sector cells are MFN (multiple frequency network) type sector cells (hereinafter, referred to as “normal cells”) that transmit different data signals at different frequencies, so that all of the plurality of sector cells are SFN. As compared with the case where the cell is used, a decrease in communication capacity via the HAPS 10 can be suppressed.

FIG. 12 is an explanatory diagram showing another example of a plurality of sector cells formed by a plurality of HAPSs 10 according to the embodiment so that a plurality of SFN cells are continuously arranged along a high-speed railway. In the example of FIG. 12, unlike FIG. 11, a sector cell 403 covering the Kanto metropolitan area centering on Tokyo where many terminal devices are concentrated, and a sector cell 403 covering the Kansai metropolitan area centering on Osaka. , SFN cells, but normal cells 403N that can secure communication capacity. As a result, a decrease in communication capacity via the HAPS 10 in the Kanto metropolitan area and the Kansai metropolitan area can be suppressed.

FIGS. 13A and 13B are explanatory views showing still another example of a plurality of sector cells formed by the HAPS 10 according to the embodiment so that a plurality of SFN cells are continuously arranged along a high-speed railway. FIG. 13A is an explanatory diagram showing an example of the arrangement of the sector cells including the SFN cells before the HAPS rotationally moves. FIG. 13B is a diagram showing the arrangement of the sector cells including the SFN cells after the cell switching control when the HAPS rotationally moves. It is explanatory drawing which shows an example.

In FIG. 13A, SFN cells 401S, 402S, and 403S are formed at the positions of three sector cells along the Shinkansen route 400 of the high-speed railway, and normal cells 404N to 407N are formed at the positions of the other four sector cells. . From this state, as shown in FIG. 13B, when the HAPS 10 in the sky moves in the downward direction of the arrow M in the figure and rotates about 45 degrees in the counterclockwise direction of the arrow R in the figure, the two SFN cells 401S and 402S become bullet trains. Departing from the route 400, the two normal cells 404N and 405N are located along the Shinkansen route 400. Therefore, in this example, control is performed such that the SFN cells 401S and 402S are switched to the normal cells 401N and 402N, and the normal cells 404N and 405N are switched to the SFN cells 404S and 405S based on the information on the movement and rotation of the HAPS 10 in the sky. ing. By performing the cell switching control in this manner, even when the HAPS 10 moves or rotates, the SFN cell is formed at a position along the Shinkansen route 400 and the normal cells N to 407N are formed at other positions. And reliably prevent communication quality degradation due to frequent handovers on the Shinkansen route 400 and increase in interference from neighboring cells, and also reliably prevent a decrease in communication capacity other than the Shinkansen route 400 it can.

FIG. 14 is a flowchart illustrating an example of the sector cell switching control in the HAPS 10 according to the embodiment. The example of FIG. 14 illustrates a PRB (physical resource block) usage rate of a downlink service link wireless communication between a terminal device located in the sector cell and the relay communication station 110 of the HAPS 10 for each of a plurality of sector cells formed by the HAPS 10. 5 is an example of sector cell switching control for switching between SFN cells and normal cells based on.

In FIG. 14, the relay communication station 110 of the HAPS 10 calculates and acquires information on the PRB (physical resource block) usage rate of the service link wireless communication for each of a plurality of sector cells formed by the HAPS 10 (S101). The PRB usage rate is a ratio of PRBs actually used for wireless communication with a terminal device located in the sector cell among PRBs available in a downlink service link in the sector cell. The information on the PRB usage rate may be calculated by reading information stored in the own station, or may be obtained from a device on the mobile communication network side (for example, the EPC or the remote control device 85).

Next, the relay communication station 110 compares the PRB usage rate with a predetermined first threshold value THD1 (S102). The threshold value THD1 is, for example, 10%, and a parameter value “SFNDLHIGHLOADTHD” may be used. Here, when the PRB usage rate is smaller than the threshold value THD1 (YES in S102) and the current sector cell is a normal cell (YES in S103), the sector cell is switched from a normal cell to an SFN cell (S104). On the other hand, if the PRB usage rate is equal to or higher than the threshold value THD1 (NO in S102) and the current sector cell is an SFN cell (YES in S105), the sector cell is switched from the SFN cell to a normal cell (S106).

(4) The relay communication station 110 repeatedly performs the acquisition and determination of the sector cell information (PRB) and the control of switching the sector cells (S101 to S106) at a predetermined determination cycle (for example, 1 to 10 seconds) (S107).

FIG. 15 is a flowchart illustrating another example of the sector cell switching control in the HAPS 10 according to the embodiment. In the example of FIG. 15, for each of a plurality of sector cells formed by the HAPS 10, the PRB (physical resource block) usage rate of the uplink service link wireless communication between the terminal device located in the sector cell and the relay communication station 110 of the HAPS 10 5 is an example of sector cell switching control for switching between SFN cells and normal cells based on.

In FIG. 15, the relay communication station 110 of the HAPS 10 calculates and obtains information on the PRB (physical resource block) usage rate of the service link wireless communication for each of a plurality of sector cells formed by the HAPS 10 (S201).

Next, relay communication station 110 compares the PRB usage rate with predetermined second threshold value THD2 (upper limit value) and third threshold value THD3 (lower limit value) (S202, S203). The second threshold value THD2 is, for example, 50%, and the third threshold value THD3 is 10%. Here, when the PRB usage rate is equal to or less than threshold value THD2 and smaller than threshold value THD3 (NO in S201, YES in S203), and when the current sector cell is a normal cell (YES in S204), the sector cell is changed from a normal cell to an SFN cell. (S205). On the other hand, if the PRB usage rate is greater than threshold value THD2 (YES in S202) and the current sector cell is an SFN cell (YES in S206), the sector cell is switched from the SFN cell to a normal cell (S207).

The relay communication station 110 repeatedly performs the acquisition and determination of the sector cell information (PRB usage rate) and the switching control of the sector cells (S201 to S207) at a predetermined determination cycle (for example, 1 to 10 seconds) (S208). .

In the control examples of FIGS. 14 and 15, the switching control of the sector cell is performed based on the PRB usage rate of the sector cell. However, the switching control of the sector cell may be performed based on information other than the PRB usage rate of the sector cell. . For example, control may be performed so as to switch to a normal cell when the traffic volume of a sector cell is higher than or equal to a predetermined threshold, and to switch to an SFN cell when the traffic volume of the sector cell is lower than a predetermined threshold.

FIG. 16 is a sequence diagram showing still another example of the sector cell switching control in the HAPS 10 according to the embodiment. The example of FIG. 16 is an example of remote control for performing sector cell switching in the HAPS 10 based on control information from the remote control device 85.

In FIG. 15, the relay communication station 110 of the HAPS 10 calculates and acquires communication information such as a PRB (physical resource block) usage rate of service link wireless communication for each of a plurality of sector cells formed by itself (S301). ), And transmits to the remote control device 85 together with device status information such as the current position, flight speed, and flight direction of the own station (S302).

The remote control device 85 includes communication information such as the PRB usage rate received from the relay communication station 110 of the HAPS 10, device status information such as the current position, flight speed, and flight direction of the HAPS 10, and the position of the vehicle movement route such as the aforementioned Shinkansen route. Based on the information and the like, cell switching control information between SFN cells and normal cells is determined for each sector cell formed by HAPS 10 (S303), and the cell switching control information is transmitted to relay communication station 110 of HAPS 10 (S303). S304).

The relay communication station 110 of the HAPS 10 executes the cell switching control between the SFN cell and the normal cell for each sector cell formed by the own station based on the cell switching control information received from the remote control device 85.

(4) The relay communication station 110 may repeatedly execute the acquisition / transmission of the communication information of the sector cell and the remote switching control of the sector cell (S301 to S2305) at a predetermined determination cycle (for example, 1 to 10 seconds).

In the example of FIG. 15, the remote control device 85 performs remote control of cell switching in a plurality of sector cells in the wide area cell 100A formed by the relay communication station 110 of the HAPS 10, for example, as illustrated in FIG. 11. May be remotely controlled so that an SFN cell is configured between a plurality of HAPSs 10. In this case, the remote control device 85 transmits various kinds of information (for example, communication information such as a PRB usage rate, device status information such as a current position, a flight speed, and a flight direction of the HAPS 10) to a plurality of sector cells formed by each of the plurality of HAPSs 10. , Position information of a vehicle movement route such as a Shinkansen route), and cell switching control information between an SFN cell and a normal cell is determined. Then, the remote control device 85 transmits the determined cell switching control information to the relay communication station 110 of each HAPS 10.

The function of the remote control device 85 may be provided in any one of the relay communication stations 110 of the plurality of HAPSs 10 that form a cell in cooperation with each other.

Also, in each of the above-described embodiments, an example has been described in which a plurality of SFN cells are selectively formed along the Shinkansen route 400. However, the positions where SFN cells are formed are not limited thereto. For example, a plurality of SFN cells may be selectively formed along a highway as a moving route along which a vehicle such as an automobile including a terminal device moves.

The processing steps described in this specification and the relay communication station, feeder station, gateway station, management device, monitoring device, remote control device, server, terminal device (user device, mobile device, etc.) of the communication relay device such as the HAPS 10 and 20 are described. The components of the station, the communication terminal), the base station, and the base station device can be implemented by various means. For example, these steps and components may be implemented in hardware, firmware, software, or a combination thereof.

For hardware implementation, entities (eg, relay communication station, feeder station, gateway station, base station, base station device, relay communication station device, terminal device (user device, mobile station, communication terminal), management device, monitoring device) , A remote control device, a server, a hard disk drive device, or an optical disk drive device), one or more application-specific ICs (ASICs), such as processing units used to implement the steps and components. , Digital signal processor (DSP), digital signal processor (DSPD), programmable logic device (PLD), field programmable gate array (FPGA), processor, controller, microcontroller, microprocessor, electronic device, book Features described in the specification Designed other electronic units to run, computer, or may be implemented in a combination thereof.

Also, for a firmware and / or software implementation, any means such as a processing unit used to implement the components may include programs (eg, procedures, functions, modules, instructions, etc.) that perform the functions described herein. , Etc.). In general, any computer / processor readable medium that explicitly embodies firmware and / or software code is a means such as a processing unit used to implement the steps and components described herein. May be used to implement For example, firmware and / or software code may be stored in a memory, for example in a control device, and executed by a computer or a processor. The memory may be implemented inside a computer or a processor, or may be implemented outside a processor. Further, the firmware and / or software code includes, for example, a random access memory (RAM), a read only memory (ROM), a nonvolatile random access memory (NVRAM), a programmable read only memory (PROM), and an electrically erasable PROM (EEPROM). ), A FLASH memory, a floppy disk, a compact disk (CD), a digital versatile disk (DVD), a magnetic or optical data storage device, etc. Good. The code may be executed by one or more computers or processors, and may cause the computers or processors to perform the functional aspects described herein.

The medium may be a non-transitory recording medium. Further, the code of the program may be executable by being read by a computer, a processor, or another device or an apparatus machine, and its format is not limited to a specific format. For example, the code of the program may be any of a source code, an object code, and a binary code, and may be a mixture of two or more of those codes.

Also, descriptions of the embodiments disclosed herein are provided to enable one of ordinary skill in the art to make or use the present disclosure. Various modifications to the present disclosure will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure is not limited to the examples and designs described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

10 HAPS (Solar plane type)
20 HAPS (airship type)
40 Cell formation target airspace 41, 42, 43 Three-dimensional sector cell 50 Airspace where HAPS is located 60 Drone 61 Terminal device 65 Airplane 70 Feeder station 72 Artificial satellite 80 Mobile communication network 85 Remote control device (control center, control center)
86 server 90 base station (eNodeB)
100, 200, 300 beams 100A Wide area sector cell 110, 210 Relay communication station 401-407 sector cell

Claims (17)

1. A communication relay device that wirelessly communicates with a terminal device,
   Equipped with a relay communication station mounted on a floating body capable of moving over the sky by autonomous control or control from the outside, forming a wide area cell consisting of a plurality of sector cells capable of wireless communication with the terminal device,
   The plurality of sector cells formed by the relay communication station are a plurality of SFNs (single-frequency networks) that are continuously arranged and transmit signals of the same data in the downlink from the relay communication station in a time-synchronized manner with the same frequency. A communication relay device comprising:
2. The communication relay device according to claim 1,
   The communication relay device, wherein the plurality of SFN sector cells are continuously formed along a moving route along which a vehicle including a terminal device moves.
3. The communication relay device according to claim 1 or 2,
   The plurality of sector cells formed by the relay communication station are a plurality of SFN sector cells and a plurality of MFNs (multi-frequency networks) that transmit different data signals at different frequencies in downlink from the relay communication station. A communication relay device comprising:
4. The communication relay device according to claim 3,
   A communication relay device comprising: a cell switching unit that selectively switches each of the plurality of sector cells formed by the relay communication station between the SFN sector cell and the MFN sector cell.
5. The communication relay device according to claim 4,
   In each of the plurality of sector cells, the cell switching unit uses the SFN scheme based on a PRB (physical resource block) usage rate of wireless communication between a terminal device located in the sector cell and the relay communication station. A communication relay device for switching between a sector cell and a sector cell of the MFN system.
6. The communication relay device according to claim 4,
   The cell switching unit performs switching between the SFN sector cell and the MFN sector cell in each of the plurality of sector cells based on a traffic situation of wireless communication with a terminal device located in the sector cell. A communication relay device characterized by the above-mentioned.
7. A system including a plurality of communication relay devices that wirelessly communicate with a terminal device,
   The plurality of communication relay devices are each mounted on a floating body that can move over the sky by autonomous control or control from the outside, and form a relay communication station that forms a wide area cell including a plurality of sector cells that can wirelessly communicate with the terminal device. With
   The plurality of sector cells formed by the relay communication stations of the plurality of communication relay devices are a plurality of consecutively arranged SFNs that transmit the same data signal in the downlink from the relay communication station in a state of being time-synchronized with each other at the same frequency. A system comprising (single frequency network) type sector cells.
8. The system of claim 7,
   The system according to claim 1, wherein the plurality of SFN-type sector cells are continuously formed by a plurality of adjacent communication relay devices among the plurality of communication relay devices.
9. The system according to claim 7 or 8,
   The system according to claim 1, wherein the plurality of SFN-type sector cells are continuously formed along a moving path along which a vehicle including a terminal device moves.
10. The system according to any one of claims 7 to 8,
    The plurality of sector cells formed by the relay communication stations of the plurality of communication relay devices are a plurality of sector cells of the SFN scheme and a plurality of different cells transmitting different data signals at different frequencies in a downlink from the relay communication station. A multi-frequency network (MFN) sector cell.
11. The system of claim 10,
    Each of the plurality of sector cells formed by the relay communication stations of the plurality of communication relay devices is referred to as a sector cell formed by the relay communication station of each of the plurality of communication relay devices. A system comprising cell switching means for switching between cells.
12. The system of claim 11,
    In each of the plurality of sector cells, the cell switching unit uses the SFN scheme based on a PRB (physical resource block) usage rate of wireless communication between a terminal device located in the sector cell and the relay communication station. A system for switching between a sector cell and the MFN scheme sector cell.
13. The system of claim 11,
    The cell switching unit performs switching between the SFN sector cell and the MFN sector cell in each of the plurality of sector cells based on a traffic situation of wireless communication with a terminal device located in the sector cell. A system characterized in that:
14. The system according to any one of claims 7 to 13,
    A remote control device for remotely controlling the plurality of communication relay devices,
    The remote control device transmits, to at least one of the plurality of communication relay devices, control information for controlling switching between the SFN type sector cell and the MFN type sector cell. system.
15. A remote control device for remotely controlling the plurality of communication relay devices in the system according to claim 7,
    A remote control apparatus for transmitting control information for controlling switching between the SFN-based sector cell and the MFN-based sector cell to at least one of the plurality of communication relay apparatuses.
16. A wide area cell comprising a plurality of sector cells by the relay communication station in a communication relay device mounted on a floating body capable of moving over the sky by autonomous control or external control by a relay communication station performing wireless communication with a terminal device A method for controlling the formation of
    The plurality of sector cells are arranged so as to include a plurality of SFN (single frequency network) type sector cells which are continuously arranged and transmit the same data signal in the downlink from the relay communication station in the same frequency and time synchronized with each other. A method comprising forming.
17. A wide area cell comprising a plurality of sector cells by the relay communication station in a communication relay device mounted on a floating body capable of moving over the sky by autonomous control or external control by a relay communication station performing wireless communication with a terminal device A program for causing a computer or a processor to execute the control of the formation of
    The plurality of sector cells are arranged so as to include a plurality of SFN (single frequency network) type sector cells which are continuously arranged and transmit the same data signal in the downlink from the relay communication station in the same frequency and time synchronized with each other. A program having a program code for forming.

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