KR102535402B1 - Method for handover operation and method for control transfer operation - Google Patents

Abstract

A handover method and a control transfer method are disclosed. A handover method according to an embodiment includes the steps of setting a channel for handover between a UAV and a ground station, measuring a channel currently being used by the UAV and reporting a measurement result to the ground station, and Requesting a handover to at least one of the control center and the CNPC network based on the measurement result, determining whether or not the at least one handover is performed, and performing the handover to the UAV based on the determined handover status. and instructing handover.

Description

Handover method and control transfer method {METHOD FOR HANDOVER OPERATION AND METHOD FOR CONTROL TRANSFER OPERATION}

The following embodiments relate to a handover method and a control transfer method.

Unmanned aerial vehicle (UAV), pilotless aircraft or drone, including all components necessary for the entire flight process, including control communication systems such as take-off/cruise, flight control, landing/recovery, etc. They are called Unmanned Aircraft Systems (UAS) or Remotely Piloted Aircraft Systems (RPAS).

These UASs consist of UAV ground control equipment, UAVs, and data links. A data link is a wireless data link between a ground radio station and an unmanned aerial vehicle, and the UAS data link can be largely divided into a UAS control and non-payload communication (CNPC) data link and a UAS mission link.

A mission data link is a link for transmitting mission-related data and is generally broader than a CNPC data link. On the other hand, the CNPC link is a link for transmitting data related to UAV flight control, UAS status monitoring, and CNPC link management, and is composed of a pilot/ATC relay link and a UAS control link. The pilot/ATC relay link is a communication link for relaying voice and data between the Air Traffic Control (ATC) and the pilot through the UAV, and the UAS control link transmits control information related to safe operation between the pilot and the UAV. This is the link to forward. In the case of the UAS control link, it can be divided into a telecommand (TC) link and a telemetry (TM) link, and the TC link includes flight trajectory control information, all UAV system control information required for safe flight, etc. TM link is an uplink that transmits UAV position/altitude/speed, UAS system operation mode and status, navigation assistance data, tracking/weather radar/video information related to detection and avoidance from UAV to ground. It is a downlink that is transmitted to the pilot of the

As a frequency for the UAV terrestrial CNPC link, the C (5030-5091 MHz) band, which was distributed as a new dedicated band in WRC-12, is mainly considered, and in addition, the L( 960-1164 MHz) bands allocated to the aeronautical mobile service may be considered. In the case of the C band, there is an advantage in that the effect of frequency interference with the existing system and the spread of the multipath delay are small, but the use of a directional antenna must be considered to secure a link margin, and the Doppler effect is five times greater than that of the L band. On the other hand, in the case of low frequency bands distributed to other aeronautical mobile services, such as the L band, the propagation characteristics are better than the C band (in the case of the L band, the propagation loss is about 14 dB lower than the C band), but the DME (Distance Measurement Equipment), ADS-B (Automatic Dependent Surveillance - Broadcast), TACAN (Tactic Air Navigation System), etc. are operating in a congested manner, which not only makes it difficult to secure frequencies, but also has the disadvantage of greatly spreading multipath delays. Therefore, it is expected that the previously secured C band is considered as the basic link of the terrestrial CNPC, and the low frequency band (eg, L or UHF band, etc.) is used to increase the availability of the CNPC link for safe operation of the UAV. Of course, they can be used in reverse or independently.

Next, there are P2P (Point-to-Point) type and P2MP (Point-to-MultiPoint) type as the terrestrial CNPC link connection type. The P2P type is a concept in which one GRS forms a data link with one UA, which has been mainly considered in existing unmanned aerial systems. In contrast, the P2MP type is a concept in which one GRS forms a data link with multiple UAs. In the P2MP type, GRSs are connected through a network to support GRS handover. Both P2P type and P2MP type GRS are connected to the network, so they can provide communication services for uninterrupted UAV control such as GRS handover, or can be built in the form of a single GRS. In the case of the P2P type, it is usually built in the form of a single GRS, and in the case of the P2MP type, it is expected to build a network-based GRS. A network-based P2MP type that can simultaneously form a communication link with multiple UAVs and form a nationwide network is expected to be considered as a next-generation CNPC link, and the related technology for such a P2MP type UAS CNPC system is still incomplete.

In addition, in order to operate the existing P2P type UAS CNPC system, a channel for CNPC must be allocated. In the existing method, when registering the UAS CNPC system with the Spectrum Authority (SA), the channel is fixed for a long time (more than 1 year in total) Since it is allocated as a channel, it is difficult to utilize the channel once assigned to a specific UAS CNPC system to other UAS CNPC systems.

Therefore, for the stable operation of UAVs and the expansion of demand for UAVs, the UAV CNPC SYSTEM operates to enable efficient use of communication frequency resources for controlling UAVs that can efficiently operate multiple UAVs in the limited frequency band dedicated to UAV control. It is imperative to do

For the stable operation of UAVs and the expansion of demand for UAVs, it is necessary to design and operate a communication system for controlling UAVs that can efficiently operate multiple UAVs in a limited frequency band for UAV control. The frequency jurisdiction does not allocate a specific frequency to a specific CNPC system fixedly, but the frequency authority manages all frequencies in real time and dynamically allocates them only when the UAS CNPC system is in operation, collects them immediately after operation is completed, and reuses the frequency in other UAS CNPC systems Dynamic channel allocation and management to enable this to be possible is required, and the UAV CNPC system must support such dynamic channel allocation and management.

A handover method and control transfer method of a communication system for controlling an UAV suitable for such a dynamic channel allocation and management method are needed. The present invention proposes a handover and control transfer operation method considering a channel allocation and management method dynamically performed in a frequency jurisdiction.

A handover method according to an embodiment includes the steps of setting a channel for handover between an UAV and a ground station, measuring a channel currently being used by the UAV, and reporting a measurement result to the ground station; Requesting a handover to at least one of the control center and the CNPC network based on the measurement result, determining whether or not the at least one handover is performed, and determining whether or not the at least one handover is performed, and performing the handover on the basis of the determined handover. and instructing handover to .

The method may further include establishing an initial channel in the UAV and the ground station to connect a radio link.

The setting step may be performed after the connecting step.

The instructing may include instructing the at least one handover command to the UAV through the ground station.

The method may further include performing, by the UAV, handover to the handover channel based on the command, and reporting handover completion to the at least one.

The reporting of handover completion may include reporting, by the UAV, handover completion to the at least one through the ground station.

The setting step may be performed after the determining step.

The handover method according to an embodiment includes setting a first channel in the second ground station, measuring the second channel by the UAV, and reporting a measurement result to the first ground station; Requesting a handover to at least one of the control center and the CNPC network based on the measurement result, determining whether or not the at least one handover is performed, and determining whether or not the at least one handover is performed, and performing the handover on the basis of the determined handover. and instructing handover to .

The first channel may be a channel for handover, and the second channel may be a channel currently in use.

The setting may include setting a first channel in the UAV and the second ground station.

The reporting of the measurement result may include reporting the measurement result when the signal quality of the second channel is equal to or less than a reference value.

The instructing may include requesting, by the at least one ground station, handover to the second ground station based on the determined handover status; responding, by the second ground station, to the handover request to the second ground station; and instructing the at least one handover to the UAV based on a response from the second ground station.

The requesting of the handover to the second ground station may include providing, by the at least one, security setting information to be used when the second ground station and the UAV communicate.

The method may further include communicating with the second ground station and the UAV using the security setting information.

The method may further include establishing an initial channel between the UAV and the first ground station to establish a radio link connection.

The method may further include performing, by the UAV, handover to the first channel based on the command, and reporting handover completion to the at least one.

The reporting of handover completion may include the steps of the at least one transmitting control communication data to the UAV, and the steps of performing handover to the first channel by the UAV based on the control communication data. can include

The transmitting may include transmitting, by the at least one, the control communication data to the UAV through the second ground station.

The reporting of handover completion may include reporting, by the UAV, handover completion to the at least one through the second ground station.

The method includes, when the at least one requests handover to the second ground station, transmitting, by the at least one, information necessary for synchronization acquisition to the second ground station, and the UAV station transmitting information necessary for synchronization acquisition The method may further include performing handover based on the information.

The first channel and the second channel may be channels for handover.

The method may further include transmitting, by the at least one, a measurement signal for handover determination to the UAV.

The reporting of the measurement result may include reporting the measurement result when the signal quality of the first channel and the second channel is higher than that of a currently used channel.

The transmitting of the signal for measurement may include requesting, by the at least one, the second ground station to determine a transmission time point for the measurement signal, and in response to the request for determining a transmission time point for the measurement signal, the second ground station may perform the transmission of the measurement signal. It may include determining signal transmission for measurement.

The determining of transmission of the measurement signal may include determining, by the second ground station, transmission of the measurement signal based on downlink channel information of the UAV.

The transmitting of the signal for measurement may include requesting, by the at least one, the UAV to determine a transmission time point for the measurement signal, and in response to the request for determining a transmission time point for the measurement signal, the UAV station determines the transmission time point for measurement. determining signal transmission.

The determining of transmission of the measurement signal may include determining transmission of the measurement signal using GNSS location information of the UAV or received signal strength of the first ground station.

A control transfer method according to an embodiment includes setting a channel for handover in a second ground station, measuring a channel currently in use, and reporting a measurement result, and determining whether or not handover is performed based on the measurement result. Determining, requesting a handover to the first control center based on the determined handover status, and determining whether to transfer the control authority in response to the request by the first control center, and based on the determined whether or not to transfer the control authority requesting the first control center to transfer the control right to the second control center, and the second control center requesting the second ground station to prepare for communication through the handover channel in response to the control transfer request; , when the second control center notifies the first control center of the transfer of control authority, the step of the first notification center instructing the UAV to perform a handover, and the UAV station responding to the command to perform the handover and performing handover to a dedicated channel.

The reporting of the measurement result may include the step of the UAV measuring the currently used channel and reporting the measurement result to the first ground station, and determining whether to perform handover based on the measurement result. , The first ground station may include a step of requesting a handover to the first control center based on the determined handover.

The reporting of the measurement result may include the second ground station measuring the currently used channel and reporting the measurement result to the second control center.

The method may further include the second control center requesting security setting information from the UAV, and the UAV station responding to the request for security setting information.

Requesting the security setting information may be performed after performing the handover.

The requesting of the security setting information includes requesting security setting information from the UAV through the second ground station, and responding to the request for security setting information includes the step of requesting the security setting information through the second ground station. Responding to a request for security setting information.

1 shows an example of a relationship with a neighboring system and information exchange for stable operation of an UAV in an UAV CNPC system according to an embodiment.
2 shows another example of relationships and information exchange between neighboring systems for stable operation of the UAV in the UAV CNPC system according to an embodiment.
3 is a diagram for explaining an example of an operation in which an UAV CNPC system performs handover within the same cell.
4 is a diagram for explaining another example of an operation in which an UAV CNPC system performs handover within the same cell.
5 is a diagram for explaining an example of an operation in which an UAV CNPC system performs inter-cell handover.
6 is a diagram for explaining another example of an operation in which an UAV CNPC system performs inter-cell handover.
FIG. 7 describes an operation in which the second ground station shown in FIG. 6 transmits a measurement signal for handover decision.
FIG. 8 describes an operation in which the UAV shown in FIG. 6 transmits a measurement signal for handover decision.
FIG. 9 is a diagram for explaining an example of an operation in which the UAV shown in FIG. 8 determines a measurement signal transmission time point for handover decision.
FIG. 10 is a diagram for explaining another example of an operation of determining, by the UAV shown in FIG. 8, a measurement signal transmission timing for handover decision.
FIG. 11 is a diagram for explaining an operation in which the UAV shown in FIG. 10 determines transmission of a signal for measurement.
12 is a diagram for explaining an example of an operation in which a control center transfers control authority.
13 is a diagram for explaining another example of an operation in which a control center transfers control authority.
14 is a diagram for explaining another example of an operation in which a control center transfers control authority.

Specific structural or functional descriptions of the embodiments according to the concept of the present invention disclosed in this specification are only illustrated for the purpose of explaining the embodiments according to the concept of the present invention, and the embodiments according to the concept of the present invention These may be embodied in various forms and are not limited to the embodiments described herein.

Embodiments according to the concept of the present invention can apply various changes and can have various forms, so the embodiments are illustrated in the drawings and described in detail herein. However, this is not intended to limit the embodiments according to the concept of the present invention to specific disclosures, and includes modifications, equivalents, or substitutes included in the spirit and scope of the present invention.

Terms such as first or second may be used to describe various components, but the components should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another component, for example, without departing from the scope of rights according to the concept of the present invention, a first component may be named a second component, Similarly, the second component may also be referred to as the first component.

It is understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, but other elements may exist in the middle. It should be. On the other hand, when an element is referred to as “directly connected” or “directly connected” to another element, it should be understood that no other element exists in the middle. Expressions describing the relationship between components, such as "between" and "directly between" or "adjacent to" and "directly adjacent to" should be interpreted similarly.

Terms used in this specification are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, it is intended to designate the terms "comprise" or "having" as the presence of a described feature, number, step, operation, component, part, or combination thereof, but one or more other features or numbers, It should be understood that the presence or addition of steps, operations, components, parts, or combinations thereof is not precluded.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and unless explicitly defined in this specification, it should not be interpreted in an ideal or excessively formal meaning. don't

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. However, the scope of the patent application is not limited or limited by these examples. Like reference numerals in each figure indicate like elements.

1 shows an example of a relationship with a neighboring system and information exchange for stable operation of an UAV in an UAV CNPC system according to an embodiment.

Referring to FIG. 1, the UAV CNPC SYSTEM 10 includes a Spectrum Authority (SA) 110, an Air Traffic Control (ATC) 120, and a ground control equipment; 130), a ground CNPC radio system (140), and an airborne CNPC radio system (150).

The UAV CNPC system 10 may be an UAV CNPC system that controls the UAV 190 in a Point-to-Point (P2P) type. The UAV 190 may include at least one of components such as Video, Flight Control, and VHF/Radio.

For the operation of the P2P UAV CNPC system, the control station 130 may request a channel from the SA 110 and receive a channel assignment K1 from the SA 110.

Next, the control station 130 transmits information (F1) including ground/unmanned CNPC Radio channel allocation information and status information (G1), communication data with the ATC (120) and UAV control data to the CNPC ground station system (through the distribution system). 140) may be transmitted (H1).

The CNPC ground station system 140 may transmit information A1 including communication data and UAV control data with the ATC 120 to Flight Control and VHF/Radio. The UAV control data may include UAV telemetry and video image data. Information A1 including communication data with the ATC 120 and UAV control data may be substantially the same as information F1 including communication data with the ATC 120 and UAV control data. In addition, the CNPC ground station system 140 may transmit CNPC UAV status information (Airborne Radio Status information; B1) to Flight Control.

The CNPC UAV system 150 may transmit information A1 including communication data and UAV control data with the ATC 120 to the CNPC ground station system 140. The CNPC ground station system 140 may transmit (H1) the information (F1) received from the CNPC UAV system 150 and the CNPC radio channel allocation information and status information (G1) to the control center 130 through a wired or wireless network. . Hereinafter, the characteristics of the UAV CNPC system 10 will be described.

The UAV CNPC system 10 can operate with the following link configuration.

1) The UAV CNPC system 10 includes multiple pairs of ground stations and UAVs, and each ground station and UAV station may form a one-to-one communication link.

2) When the UAV CNPC system 10 is a standalone system, the UAV CNPC system 10 can expand coverage by switching over to a Ground Radio Station (GRS) at a control center and transferring control.

3) The UAV CNPC system 10 implements an FDMA-based ground station so that one ground station can support multiple P2P type UAVs.

The uplink channel and the downlink channel of the UAV CNPC system 10 may operate in the following configuration.

1) The UAV CNPC system 10 can operate with FDMA channels in uplink (ground station -> UAV) and downlink (UAV -> ground station).

2) The UAV CNPC system 10 may support simultaneous transmission and reception in a dual-band channel (eg, L-band and C-band).

3) The UAV CNPC system 10 can support multiple channel bandwidths (eg, 4 Data Classes (DC1) with 30/60/90/120 kHz).

4) The UAV CNPC system 10 supports different number of supported channel bandwidths for each link direction and band.

5) The UAV CNPC system 10 may support DC1, DC2, or DC3 in uplink and support DC1, DC2, DC3, DC4, DC5, or DC6 in downlink.

6) The UAV station of the UAV CNPC system 10 can support simultaneous transmission of two FDMA channels. For example, the two FDMA channels may be one of DC1 to DC4 for UAV control and one of DC5 to DC6 for safety video.

7) The UAV CNPC system 10 can operate in a fixed channel except for channel reallocation and handover.

2 shows another example of relationships and information exchange between neighboring systems for stable operation of the UAV in the UAV CNPC system according to an embodiment.

Referring to FIG. 2, the UAV CNPC system 20 includes SA 210, ATC 220, control centers 230-1 to 230-N, CNPC ground station system 240, and CNPC UAV system 250-1 ~250-3). The UAV CNPC system 20 may be a Point-to-Multi-Point (P2MP) type UAV CNPC system that controls the UAVs 290-1 to 290-3. The UAVs 290-1 to 290-3 may include at least one of components such as Video, Flight Control, and VHF/Radio.

The SA 210, the ATC 220, the control stations 230-1 to 230-N, the CNPC ground station system 240, and the CNPC UAV systems 250-1 to 250-3 are the SAs shown in FIG. 1 ( 110), the ATC 120, the control center 130, the CNPC ground station system 140, and the CNPC UAV system 150 may have substantially the same configuration and operation.

In FIG. 2, for convenience of description, three CNPC UAV systems (250-1 to 250-3) and three UAVs (290-1 to 290-3) are shown, but are not necessarily limited thereto, and a plurality of UAV systems and It can be implemented with a plurality of UAVs.

For the operation of the P2MP UAV CNPC system, the controllers 230-1 to 230-N may request a channel from the SA 210 and receive a channel assignment K1 from the SA 210.

Next, the control centers (230-1 to 230-N) transmit information (F1) including communication data with the ATC (220) and UAV control data to the CNPC ground station system (240) through the distribution system (H1 to Hn) can do. The SA 210 may transmit each UAV channel assignment information (K1 to Kn) to the CNPC ground station system 240. The CNPC ground station system 240 transfers information (A1 to An) including communication data and UAV control data with the ATC 120 received from the control centers 230-1 to 230-N to each control center 230-1 to 230-N. It can be transmitted to Flight Control and VHF/Radio of UAVs (290-1 to 290-3) controlled by N). The UAV control data may include UAV telemetry and video image data. Information (A1 to An) including communication data with the ATC 120 and UAV control data may be substantially the same as information (F1 to Fn) including communication data with the ATC 120 and UAV control data. In addition, the CNPC ground station system 240 may transmit CNPC UAV state information (B1 to Bn) to Flight Control.

The CNPC UAV systems 250-1 to 250-3 deliver information (A1 to An) including communication data and UAV control data with the ATC 120 relayed from the VHF/UHF Radio to the CNPC ground station system 240. can The CNPC ground station system 240 transmits information (F1 to Fn) and CNPC Radio channel allocation information and status information (G1 to Gn) received from a plurality of CNPC UAV systems (250-1 to 250-3) through a wired/wireless network. It can be delivered (H1 to Hn) to the corresponding control center (230-1 to 230-N).

The control communication service for safe navigation provided by the UAV CNPC system 20 between the control centers 230-1 to 230-N and the UAVs 290-1 to 290-3 depends on uplink or downlink. can be different. For example, in the case of uplink, the communication service for control for safe navigation includes at least one of Telecommand information, ATC Relay information, and NavAid setting information, and in the case of downlink, the communication service for control for safe navigation includes Telemetry information and ATC Relay. It may include at least one of information, NavAid information, DAA Target information, Weather Radar information, safety take-off landing video information, and emergency video information. ATC relay information may include ATC voice and data relay information.

The UAV CNPC system 20 may define and provide various types of Service Classes to provide various services according to channel capacity. The channel capacity may be the CNPC channel capacity for the UAVs 290-1 to 290-3.

For example, the CNPC UAV system 250-1 to 250-3 can provide various service classes according to the allocated channel bandwidth or channel capacity by defining the service class as shown in Table 1 in the case of uplink. In addition, the CNPC UAV station systems 250-1 to 250-3 can provide various service classes according to the allocated channel bandwidth or channel capacity by defining the service class as shown in Table 2 in the case of downlink.

The services provided by the CNPC UAV system (250-1~250-3) are telecommand information (uplink, ground station -> UAV station) and telemetry information (downlink) to control the UAVs (290-1~290-3). , UAV -> ground station) must be included. In addition, at least one of TC/TM data, ATC relay information, NavAid information, DAA target information, weather radar information, and video information may be further included according to the capabilities of the ground radio station and the onboard radio station and the assigned channel capacity or bandwidth.

The CNPC UAV systems (250-1 to 250-3) provide video services (safe take-off and landing video information and/or emergency video information) that can be considered during take-off and landing and emergencies through a single band of a separate downlink channel (e.g. For example, it can be provided through C band for UAV control). In other words, the CNPC UAV system (250-1~250-3) uses one Service Class among Service Classes 1 to 4 and one Service Class among Service Classes 5 to 6 in the C band during takeoff and landing or en-route emergency. can be simultaneously transmitted through different channels of

The UAV CNPC system 20 may operate in dual band to satisfy 99.999% link availability. For example, the CNPC UAV station systems 250-1 to 250-3 may operate in a dual band of a C band and an L band allocated for UAV control. The UAV CNPC system 20 can transmit the same information or different information in dual bands. When CNPC UAV systems (250-1 to 250-3) transmit the same information, signal diversity gain between L and C bands can be obtained in the physical layer, and when different information is transmitted, C band and L band A different bandwidth may be allocated from the SA 210 for .

At this time, the C band is a frequency band dedicated to the UAV and can be used for the CNPC of the UAV with the entire frequency band of 61 MHz. For example, the CNPC UAV systems 250-1 to 250-3 may transmit at least one of TC/TM data, ATC relay information, DAA target information, and weather radar information in C band.

In the case of the L band, interference with other aeronautical radio devices may exist. For example, the CNPC UAV systems 250-1 to 250-3 may transmit TC/TM data in the L band. Hereinafter, the characteristics of the UAV CNPC system 20 will be described.

The UAV CNPC system 20 can operate with the following link configuration.

1) The UAV CNPC system 20 may include a plurality of ground stations simultaneously supporting a plurality of UAV stations.

2) When the UAV CNPC system 20 is connected to a network, the UAV CNPC system 20 may expand coverage through handover between ground stations.

3) The UAV CNPC system 20 implements a TDM-based ground station so that one ground station can support multiple UAV stations.

The uplink channel and the downlink channel of the UAV CNPC system 20 may operate in the following configuration.

1) The UAV CNPC system 20 can operate with a TDM channel in uplink (ground station -> UAV station).

2) The UAV CNPC system 20 may allocate different TDM time slots for each UAV station and classify the UAV stations according to the TDM time slots.

3) The UAV CNPC system 20 may fix and allocate the frequency and channel bandwidth (number of TDM slots) of the ground station. The UAV CNPC system 20 may change the number of TDM slots when performing long-term update.

4) The UAV CNPC system 20 can flexibly change the number and location of slots allocated to the UAV communicating with the ground station to simultaneously support multiple UAV stations and efficiently support channel change within a cell.

5) The UAV CNPC system 20 can operate with an FDMA channel in downlink (UAV -> ground station).

6) The UAV CNPC system 20 may support simultaneous transmission and reception in a dual-band channel (eg, L-band and C-band).

7) The UAV CNPC system 20 can support multiple channel bandwidths (eg, 8 channel bandwidths with 90/180/270/360/450/540/630/720 kHz).

8) The UAV CNPC system 20 may support different numbers of TDM time slots according to uplink channel bandwidth. For example, the UAV CNPC system 20 may support 3 slots for 90 kHz, 6 slots for 180 kHz, and 24 time slots for 720 kHz.

9) The UAV CNPC system 20 may support different numbers of channel bandwidths for each link direction and band. For example, the UAV CNPC system 20 may support 90/180/270/360/450/540/630/720 kHz for uplink and 30/40/90/120 kHz for downlink. there is.

10) The UAV station of the UAV CNPC system 20 can support simultaneous transmission of two FDMA channels. For example, the two FDMA channels may be one of DC1 to DC4 for UAV control and one of DC5 to DC6 for safety video.

11) The UAV CNPC system 20 may operate in a fixed channel except for channel reallocation and handover.

Hereinafter, a handover method and a control transfer method of the UAV CNPC system 10 or 20 will be described.

3 is a diagram for explaining an example of an operation in which an UAV CNPC system performs handover within the same cell.

Referring to FIG. 3 , the UAV CNPC system may be implemented as the UAV CNPC system 10 shown in FIG. 1 or the UAV CNPC system 20 shown in FIG. 2 . The UAV CNPC system includes a control station or CNPC network 330, a ground station 340, and an UAV station 350. The control center, the ground station 340, and the drone station 350 are the control stations 130 and 230-1 to 230-N shown in FIGS. 1 and 2, the CNPC ground station systems 140 and 240, and the CNPC drone station system ( 150 and 250-1 to 250-3) may have substantially the same configuration and operation. The CNPC network may be a communication network formed between the control station and the ground station 340 . For example, the CNPC network may perform handover using the identities of the control center and the ground station 340 .

The UAV 350 and the ground station 340 may perform a radio link connection with each other through channel setup and initial access. The UAV 350 and the ground station 340 may set a channel for handover by setting a frequency for handover. At this time, the UAV 350 and the ground station 340 may establish a channel for handover after performing a radio link connection.

When the UAV CNPC system performs handover within the same cell, the UAV 350 measures the quality of the channel currently being used, and the control center or CNPC network 330 determines handover based on the measured quality. can The quality of the currently used channel measured by the UAV 350 may be based on signal quality.

When the quality (eg, signal quality) measured by the UAV 350 is equal to or less than a predetermined threshold, the UAV 350 may report the measurement result to the ground station 340 . In this case, the UAV 350 may periodically report measurement results. The UAV 350 may report the measurement result to the ground station 340 based on a preset period. The UAV 350 may be configured to periodically report measurement results to the ground station 340 even when the signal quality is higher than a reference value.

The ground station 340 may request handover to the control center or the CNPC network 330 based on the measurement result.

The control center or CNPC network 330 may determine whether to perform handover in response to the handover request. When the control center or the CNPC network 330 determines handover, the control center or the CNPC network 330 may transmit a handover command to the ground station 340 .

The ground station 340 may transmit a handover command to the UAV 350 in response to the handover command, and change transmission/reception settings to a handover channel.

In response to the handover command, the UAV 350 may change transmission/reception settings from a currently used channel to a handover channel. The UAV 350 may transmit a handover completion message through the changed channel.

The ground station 340 may receive a handover complete message on a channel allocated for handover. The ground station 340 may report handover completion to the control center or CNPC network 330 to complete the handover procedure.

In the case of performing communication for UAV control in the UAV CNPC system, the control center or CNPC network 330 may perform communication by being allocated a primary channel and two secondary channels in C band and L band. The control center or CNPC network 330 may determine whether to perform handover based on a channel having poorer signal quality among Primary and Secondary.

4 is a diagram for explaining another example of an operation in which an UAV CNPC system performs handover within the same cell.

Referring to FIG. 4 , the UAV CNPC system may be implemented as the UAV CNPC system 10 shown in FIG. 1 or the UAV CNPC system 20 shown in FIG. 2 . The UAV CNPC system includes a control station or CNPC network 430 , a ground station 440 , and an UAV station 450 . The control center or CNPC network 430, the ground station 440, and the drone station 450 are substantially configured and operated with the control center or CNPC network 330, the ground station 340, and the drone station 350 shown in FIG. can be the same as

The UAV CNPC system can exchange (replace) one of the two channels. For example, the control center or CNPC network 430 may be allocated two channels, Primary and Secondary, and use them for transmission and reception at the same time in order to perform communication for controlling the UAV. At this time, when one of the two channels is in a bad state, the control center or the CNPC network 430 may perform handover by assigning the bad channel as a new channel. When the ground station 440 requests handover, the control center or CNPC network 430 may receive a channel for handover and set a channel for handover.

When the UAV CNPC system performs handover in the same cell, the UAV 450 and the ground station 440 can simultaneously change settings to a changed channel (eg, handover channel) to continue communication. In this case, when transmitting a handover command to the UAV 450, the ground station 440 may also transmit timing information for changing to a channel for handover. Accordingly, the UAV 450 and the ground station 440 can perform communication by changing to a channel for handover at the same timing.

5 is a diagram for explaining an example of an operation in which an UAV CNPC system performs inter-cell handover.

Referring to FIG. 5, the UAV CNPC system may perform inter-cell handover. The UAV CNPC system includes a control center or CNPC network 530, a first ground station 540-1, a second ground station 540-2, and an UAV 550. The control center, the first ground station 540-1, the second ground station 540-2, and the unmanned aerial vehicle station 550 are the control centers 130 and 230-1 to 230-N shown in FIGS. 1 and 2, CNPC ground stations The systems 140 and 240 and the CNPC UAV systems 150 and 250-1 to 250-3 may have substantially the same configuration and operation. The CNPC network may be a communication network formed between the control center and the ground stations 540-1 and 540-2. For example, the CNPC network may perform handover using the identities of the control center and ground stations 540-1 and 540-2.

The UAV 550 and the first ground station 540-1 may perform radio link connection through channel setup and initial access. The drone station 550 and the second ground station 540-2 may set a channel for handover by setting a frequency for handover.

The UAV 550 may measure the quality of a channel currently in use. The quality of the currently used channel measured by the UAV 550 may be based on signal quality. When the signal quality is equal to or less than the reference value, the UAV 550 may report the measurement result to the first ground station 540-1. In this case, the UAV 550 may periodically report measurement results. The UAV 550 may report the measurement result to the first ground station 540-1 based on a preset period. The UAV 550 may be configured to periodically report the measurement result to the first ground station 540-1 even when the signal quality is higher than a reference value.

The first ground station 540-1 may request handover to the control center or the CNPC network 530 based on the measurement result. The control center or CNPC network 530 may determine whether to perform handover in response to the handover request. When the control center or the CNPC network 530 determines handover, the control center or the CNPC network 530 may request handover from the second ground station 540-2 and receive a response to the handover request.

The control center or CNPC network 530 may provide security setting information when requesting handover to the second ground station 540-2. Security setting information may be information used in communication between the UAV 550 and the second ground station 540-2.

The second ground station 540-2 may prepare for transmission/reception on a handover channel. For example, the second ground station 540-2 sets transmission and reception on a handover channel and prepares to receive signals from the UAV 550 and/or control communication data from the control center or CNPC network 530. can When control communication data is received from the control center or the CNPC network 530, the second ground station 540-2 may perform transmission through a channel for handover. The control communication data may be the same data transmitted from the control center or the CNPC network 530 to the first ground station 540-1.

The control center or CNPC network 530 may transmit a handover command to the first ground station 540-1, and the first ground station 540-1 may transmit a handover command to the UAV 550. The handover command received from the UAV 550 may include security setting information. The drone station 550 may use security setting information when communicating with the second ground station 540-2.

The UAV 550 may perform handover in response to a handover command. That is, the UAV 550 can change a channel currently in use to a channel for handover. The UAV 350 may transmit a handover complete message to the second ground station 540-2.

The second ground station 540 - 2 may report handover completion to the control center or the CNPC network 530 in response to the handover completion message. The control center or CNPC network 530 notifies the first ground station 540-1 of handover completion, and the first ground station 540-1 may terminate data transmission and reception with the UAV 550.

The UAV 550 measures a signal from the second ground station 540-2 for a predetermined period of time before changing from a channel in use to a channel for handover, and obtains a frequency offset and a time offset related to synchronization acquisition. offset), or information such as AGC may be acquired in advance. Accordingly, when the UAV 550 changes to a channel for handover and connects a radio link, synchronization may be obtained using information related to synchronization acquisition.

When the control center or the CNPC network 530 requests handover from the second ground station 540-2, information on the channel currently being used by the UAV 550 may be transmitted together. Accordingly, the second ground station 540 - 2 may perform a reception operation on the channel currently being used by the UAV 550 and acquire information necessary for obtaining synchronization in advance.

The first ground station 540 - 1 and the second ground station 540 - 2 may transmit the same data to the UAV 550 . Also, the first ground station 540-1 and the second ground station 540-2 can always receive a message transmitted by the UAV 550. Accordingly, data transmitted/received between the control center or the CNPC network 530 and the UAV 550 may not be lost irrespective of timing when the UAV 550 changes channels for handover.

6 is a diagram for explaining another example of an operation in which an UAV CNPC system performs inter-cell handover.

Referring to FIG. 6, the UAV CNPC system may perform inter-cell handover. The UAV CNPC system includes a control center or CNPC network 630, a first ground station 640-1, a second ground station 640-2, and an UAV 650. The control center, the first ground station 640-1, the second ground station 640-2, and the drone station 650 are the control centers 130 and 230-1 to 230-N shown in FIGS. 1 and 2, CNPC ground stations The systems 140 and 240 and the CNPC UAV systems 150 and 250-1 to 250-3 may have substantially the same configuration and operation. The CNPC network may be a communication network formed between the control center and the ground stations 640-1 and 640-2. For example, the CNPC network may perform handover using the identities of the control center and ground stations 640-1 and 640-2.

Initially, in the UAV CNPC system, only the second ground station 640-2 can set a channel for handover. In this case, the second ground station 640-2 may transmit a signal for measurement to the control center or CNPC network 630, the first ground station 640-1, and the UAV 650 for handover decision. An operation in which the second ground station 640-2 transmits a signal for measurement will be described later with reference to FIGS. 7 and 8 .

The UAV 650 may measure the quality of the channel for handover and compare it with the quality of the currently used channel. When the quality of the channel for handover is higher than that of the current channel by a reference value or higher, the UAV 650 may perform a measurement report to the first ground station 640-1. In the case of the measurement report of the UAV 650, as described above with reference to FIG. 3, a periodic measurement report or a periodic measurement report above or below a reference value may be possible.

The first ground station 640-1 may receive the measurement report and operate as described above with reference to FIG. 5 . In addition, the control center or the CNPC network 630 may determine whether to perform handover based on the signal for measurement.

FIG. 7 describes an operation in which the second ground station shown in FIG. 6 transmits a measurement signal for handover decision.

Referring to FIG. 7 , the UAV CNPC system includes a control center or CNPC network 730, a first ground station 740-1, a second ground station 740-2, and an UAV 750. The control center or CNPC network 730, the first ground station 740-1, the second ground station 740-2, and the UAV 750 are the control center or CNPC network 630 shown in FIG. 6, the first ground station ( 640-1), the second ground station 640-2, and the UAV 650 may have substantially the same configuration and operation.

The control center or the CNPC network 730 may request the second ground station 740-2 to determine a measurement signal transmission time point. At this time, the control center or the CNPC network 730 may also provide downlink channel information currently being used by the UAV for communication with the first ground station 740-1.

The second ground station 740-2 may transmit a response to a request for determining a signal transmission time point for measurement and measure the received signal strength of a channel transmitted by the UAV using downlink channel information. The second ground station 740-2 may determine measurement signal transmission when the received signal strength is greater than or equal to the reference value, and may request measurement signal transmission data from the control center or CNPC network 730.

The control center or CNPC network 730 may transmit a response to the request for measurement signal transmission data and transmit the same data as the data transmitted to the first ground station 740-1 to the second ground station 740-2. .

Upon receiving a response to the data request for measurement signal transmission, the second ground station 740-2 may change transmission/reception settings to a handover channel.

The control center or CNPC network 730 may request channel measurement for handover to the UAV 750 through the first ground station 740-1 and transmit channel information for handover together. When receiving a response to the request from the UAV 750, the control center or CNPC network 730 may complete a signal transmission procedure for measurement. The control center or CNPC network 730 may receive a response to the request through the first ground station 740-1.

The measurement signal transmission data transmitted from the control center or CNPC network 730 to the second ground station 740-2 is the same data as the data transmitted to the first ground station 740-1 as described above, or is predefined. may be data.

When the second ground station 740-2 uses predefined data as signal data for measurement, the second ground station 740-2 does not receive data for signal transmission for measurement from the control center or the CNPC network 730. may not be Security may be applied to a radio link between the UAV 750 and the ground station 740-1 or 740-2.

When the second ground station 740-2 uses the same data as the data transmitted to the first ground station 740-1 as measurement signal data, the second ground station 740-2 responds to the data request for measurement signal transmission. A response and security setting information may be received together from the control center or the CNPC network 730 .

When the second ground station 740-2 considers soft handover, the same setting information as the security settings currently applied by the first ground station 740-1 and the UAV 750 is transmitted to the control center or the CNPC network ( 730) can be received and applied.

When the second ground station 740 - 2 considers hard handover, it may receive and apply security setting information to be used after handover from the control center or the CNPC network 730 .

The second ground station 740-2 may measure the channel being used by the UAV 750 in various ways depending on the antenna and RF configuration. When the second ground station 740-2 uses a tracking antenna, measurements may be performed in a direction in which the first ground station 740-1 is located in a cell where the UAV currently exists. When the second ground station 740-2 uses an omni-directional antenna, measurements can be performed without special settings. When the second ground station 740 - 2 uses a sector antenna, measurements may be performed on antennas facing the direction of the cell where the UAV currently exists. The second ground station 740-2 may periodically measure antennas facing the direction of the cell where the UAV currently exists. In this case, when the RF configuration of the second ground station 740-2 supports measurement of several antennas at once, measurement of antennas may be performed at once.

The UAV 750 may apply information such as frequency offset, time offset, or AGC obtained while performing handover channel measurement to the receiver. For example, the UAV 750 may apply information to the receiver when changing from a channel being used to a channel for handover. Accordingly, the UAV 750 may acquire reception synchronization.

The second ground station 740-2 may perform a reception operation on a channel currently used by the UAV 750 until it receives a handover completion message from the UAV 750 on the handover channel. When the UAV 750 performs handover, only the channel is changed in the same C band or L band, and information such as frequency offset, time offset, or AGC obtained from the channel currently used by the UAV 750 Reception synchronization can be obtained immediately by applying to reception of a channel for handover.

FIG. 8 describes an operation in which the UAV shown in FIG. 6 transmits a measurement signal for handover decision.

Referring to FIG. 8 , the UAV CNPC system includes a control center or CNPC network 830, a first ground station 840-1, a second ground station 840-2, and an UAV 850. The control center or CNPC network 830, the first ground station 840-1, the second ground station 840-2, and the drone station 850 are the control center or CNPC network 630 shown in FIG. 6, the first ground station ( 640-1), the second ground station 640-2, and the UAV 650 may have substantially the same configuration and operation.

The control center or the CNPC network 830 may request the UAV 850 to determine a signal transmission time point for measurement. For example, the control center or the CNPC network 830 may request the UAV 850 to determine the measurement signal transmission time point through the first ground station 840-1 and receive a response.

The UAV 850 may determine a signal transmission time point for measurement using channel state information and/or location information currently in use. The UAV 850 may combine channel state information and location information to determine a signal transmission time point for measurement. The control center or the CNPC network 830 may provide information on which method and which reference value the UAV 850 uses to determine a signal transmission time point for measurement. For example, the control center or the CNPC network 830 may provide information to the UAV 850 when requesting a measurement signal transmission time determination.

The UAV 850 may report the event to the first ground station 840-1 when an event indicating that transmission of a measurement signal is required occurs. In response to the event report, the first ground station 840-1 may request transmission of a measurement signal from the control center or the CNPC network 830. The control center or CNPC network 830 may command the second ground station 840-2 to transmit a signal for measurement. When the control center or CNPC network 830 receives a response to the command from the second ground station 840-2, the control center or CNPC network 830 sends the first ground station 840-1 to the second ground station 840-2. ) can deliver the same data as the control data delivered to. When the first ground station 840 - 1 receives a response to the measurement signal transmission request from the control center or the CNPC network 830 , the first ground station 840 - 1 may request the UAV 850 to set a channel measurement for handover. Accordingly, the UAV 850 may perform channel measurement.

The signal transmission data for measurement transmitted from the control center or CNPC network 830 to the second ground station 840-2 is the same data as the data transmitted to the first ground station 840-1 as described above, or is predefined. may be data.

When the second ground station 840-2 uses predefined data as signal data for measurement, the second ground station 840-2 does not receive data for signal transmission for measurement from the control center or the CNPC network 830. may not be Security may be applied to a radio link between the UAV 850 and the ground station 840-1 or 840-2.

When the second ground station 840-2 uses the same data as the data transmitted to the first ground station 840-1 as signal data for measurement, the second ground station 840-2 is a control center or CNPC network 830 It is possible to receive a measurement signal transmission command and security setting information together from

When the second ground station 840-2 considers soft handover, the same setting information as the security settings currently applied by the first ground station 840-1 and the UAV 850 is received from the control center or the CNPC network 830 that can be applied.

When the second ground station 840 - 2 considers hard handover, it may receive and apply security setting information to be used after handover from the control center or the CNPC network 830 .

7 and 8 illustrate a configuration in which the second ground station 740-2 or the UAV 850 determines the measurement signal transmission timing for convenience of description, but is not limited thereto, and the control center or CNPC network When the 730 or 830 sets a channel for handover, a signal for measurement may be directly transmitted to the UAV 750 or 850.

FIG. 9 is a diagram for explaining an example of an operation in which the UAV shown in FIG. 8 determines a measurement signal transmission time point for handover decision.

8 and 9, the UAV 850 may utilize GNSS location information and/or received signal strength from a currently connected ground station 840-1 or 840-2 to determine a signal transmission time point for measurement. there is.

When the UAV 850 determines the measurement signal transmission timing using GNSS location information, the UAV 850 may set the area 900 in advance. Area 900 may be an area where measurement for handover starts. When the UAV enters the area 900, the UAV 850 may request the control center or CNPC network 830 to transmit a signal for measurement.

When the UAV 850 determines the measurement signal transmission timing using the received signal strength from the ground station 840-1 or 840-2, the UAV 850 may monitor the received signal strength. The received signal strength may be the strength of a signal received in current communication. The UAV 850 may determine signal transmission for measurement when the received signal strength falls below a predetermined critical value.

FIG. 10 is a diagram for explaining another example of an operation of determining when the UAV shown in FIG. 8 transmits a signal for measurement for handover decision, and FIG. It is a drawing for explaining the operation of determining.

Referring to FIGS. 8, 10, and 11, the UAV 850 determines a signal transmission time for measurement using GNSS location information and received signal strength from a currently connected ground station 840-1 or 840-2. can The UAV 850 divides the areas into R-1 area 1010, R-2 area 1020, and It can be divided into R-3 area (1030).

Area R-1 1010 is an area closest to the current ground station 840-1 or 840-2, and may be an area where handover does not occur. That is, the UAV 850 may not consider signal transmission for measurement when the UAV is located in the area R-1 1010 .

Area R-2 1020 may be an area where handover occurs in some cases. For example, when signal quality is poor due to terrain, the UAV 850 may perform handover.

Region R-3 1030 may correspond to region 900 shown in FIG. 9 . That is, when the UAV 850 is located in the area R-3 1030, the UAV 850 may request the control center or the CNPC network 830 to transmit a signal for measurement.

The UAV 850 may determine signal transmission for measurement using GNSS location information and received signal strength from the currently connected ground station 840-1 or 840-2.

The UAV 850 may receive current GNSS location information from a GNSS module and receive received signal strength from a currently connected ground station 840-1 or 840-2. The UAV 850 may check the location of the UAV using the current GNSS location information.

A GNSS module may refer to hardware capable of performing functions and operations for measuring GNSS location information, may refer to computer program codes capable of performing specific functions and operations, or may refer to hardware capable of performing specific functions and operations. It may refer to an electronic recording medium, for example, a processor or a microprocessor, in which a computer program code capable of being used is loaded. In other words, a GNSS module may mean a functional and/or structural combination of hardware for performing an operation of GNSS location information measurement and/or software for driving the hardware.

When the UAV is currently located in the R-1 area 1010, the UAV 850 may repeat reception of GNSS location information and received signal strength. That is, the GNSS module and the ground station 840-1 or 840-2 can continuously measure GNSS location information and received signal strength.

When the UAV is currently located in the R-2 area 1020, the UAV 850 may compare the received signal strength with a threshold value. If the received signal strength is greater than the threshold value, the GNSS location information and received signal strength may be measured again. When the received signal strength is smaller than the threshold value, the UAV 850 may determine to transmit the signal for measurement.

When the UAV is currently located in the R-3 area 1030, the UAV 850 may determine signal transmission for measurement regardless of the received signal strength.

12 is a diagram for explaining an example of an operation in which a control center transfers control authority.

Referring to FIG. 12, the UAV CNPC system includes a first control station 1230-1, a second control station 1230-2, a first ground station 1240-1, a second ground station 1240-2, and an UAV station ( 1250). The first control station 1230-1, the second control station 1230-2, the first ground station 1240-1, the second ground station 1240-2, and the drone station 1250 are shown in FIGS. 1 and 2. The configuration and operation may be substantially the same as the control stations (130 and 230-1 to 230-N), CNPC ground station systems (140 and 240), and CNPC UAV systems (150 and 250-1 to 250-3). .

The first control center 1230-1 may request a channel from the SA (frequency authority) and receive channel allocation from the SA. The first ground station 1240-1 and the UAV 1250 may be connected using the assigned channel.

The second control center 1230 - 2 may request a channel for transferring the control right of the UAV to the SA, and may be allocated a channel for transferring the control right of the UAV from the SA. The second control center 1230-2 may set a channel for transferring the control right of the UAV to the second ground station 1240-2 and provide channel information for transferring the right to control the UAV to the first control center 1230-1. .

The drone station 1250 may measure a channel currently being used with the first ground station 1240-1. In this case, when the signal quality of the currently used channel is equal to or less than the reference value, the UAV 1250 may report the measurement result to the first ground station 1240-1.

The first ground station 1240-1 may request a handover from the first control center 1230-1 in response to the measurement result. The first control center 1230-1 may determine control transfer in response to the handover request.

When the first control center 1230-1 decides to transfer control, the first control center 1230-1 may request the second control center 1230-2 to initiate the transfer of control.

The second control center 1230-2 may request the second ground station 1240-2 to prepare a radio link connection with the UAV and receive a response in response to the control transfer start request. In addition, the second control center 1230-2 may transmit a control transfer procedure start message to the first control center 1230-1. The second ground station 1240-2 may configure transmission/reception as a handover channel for connection with the UAV and prepare for a radio link connection. The first control center 1230-1 may transmit a handover command to the UAV 1250 through the first ground station 1240-1 in response to the control transfer procedure start message.

The UAV 1250 may perform a handover from a currently used channel to a handover channel, and transmit a handover completion message to the second ground station 1240-2. The second ground station 1240-2 may report handover completion to the second control center 1230-2. The second control center 1230-2 may transmit a control transfer completion message to the first control center 1230-1. The first control center 1230-1 may transfer a handover completion message to the first ground station 1240-1 to terminate transmission and reception operations with the UAV 1250.

In the control transfer process, when the first control center (1230-1) requests the second control center (1230-2) to initiate the control transfer, the first control center (1230-1) sends a request to the second control center (1230-2). , security-related setting information currently applied between the first ground station 1240-1 and the UAV 1250 may be delivered together.

The second control center 1230-2 may update the security key based on security-related setting information. The security key may be used for a radio link connection between the second ground station 1240-2 and the UAV 1250. The second control station 1230-2 may provide the second ground station 1240-2 with an updated security key when a radio link connection preparation request with the UAV 1250 is requested. In addition, when the second control center 1230-2 confirms the start of the transfer of control authority to the first control center 1230-1, security setting information to be used by the second ground station 1240-2 and the UAV 1250 is also included. can provide The UAV 1250 may set security based on provided security setting information. The first control center 1230-1 may include security setting information in the handover command and provide it to the UAV 1250.

13 is a diagram for explaining another example of an operation in which a control center transfers control authority.

Referring to FIG. 13, the UAV CNPC system includes a first control station 1330-1, a second control station 1330-2, a first ground station 1340-1, a second ground station 1340-2, and an UAV station ( 1350). The first control station 1330-1, the second control station 1330-2, the first ground station 1340-1, the second ground station 1340-2, and the UAV 1350 are the first control station 1350 shown in FIG. The configuration and operation of the control center 1230-1, the second control center 1230-2, the first ground station 1240-1, the second ground station 1240-2, and the UAV 1250 may be substantially the same. there is.

When the first control center 1330-1 and the second control center 1330-2 do not share security settings, the UAV 1350 and the second ground station 1340-2 transmit handover completion immediately after the handover. Security may not be applied to messages.

In response to receiving the handover complete message, the second control center 1330-2 may request security settings from the UAV 1350 through the second ground station 1340-2. In response to the security setting request, the UAV 1350 may transmit a security setting response to the second control center 1330-2 through the second ground station 1340-2.

14 is a diagram for explaining another example of an operation in which a control center transfers control authority.

Referring to FIG. 14, the UAV CNPC system includes a first control station 1430-1, a second control station 1430-2, a first ground station 1440-1, a second ground station 1440-2, and an UAV station ( 1450). The first control station 1430-1, the second control station 1430-2, the first ground station 1440-1, the second ground station 1440-2, and the UAV 1450 are the first control station 1450 shown in FIG. The configuration and operation of the control center 1230-1, the second control center 1230-2, the first ground station 1240-1, the second ground station 1240-2, and the UAV 1250 may be substantially the same. there is.

The second control center 1430-2 may request the start of control transfer to the first control center 1430-1 based on the measurement result of the second ground station 1440-2.

The first control center 1430-1 may request a channel from the SA (frequency authority) and receive channel allocation from the SA. The first ground station 1440-1 and the UAV 1450 may be connected using the assigned channel.

The second control center 1430-2 may request a channel for transferring the control right of the UAV and may be allocated a channel for transferring the control right of the UAV from the SA. The second control center 1430-2 may set a channel for transferring the control right of the UAV to the second ground station 1440-2 and provide channel information for transferring the right to control the UAV to the first control center 1430-1. .

The first control center 1430-1 may deliver a response to the received channel information and downlink channel information currently used by the UAV 1450 to the second control center 1430-2. The second control center 1430-2 may provide downlink channel information currently being used by the UAV 1450 to the second ground station 1440-2. The second ground station 1440-2 may measure the UAV 1450 based on downlink channel information currently in use.

The second ground station 1440-2 may measure the downlink channel of the UAV 1450. The second ground station 1440-2 may measure the downlink channel by measuring the received signal strength. When the received signal strength is greater than or equal to the reference value, the second ground station 1440-2 may report the measurement result to the second control center 1430-2. As described above with reference to FIG. 3 , the second ground station 1440 - 2 may perform periodic reporting or may perform periodic reporting above a reference value.

The second control center 1430-2 may determine a control transfer start request based on the measurement result report, and may request the first control center 1430-1 to start the control transfer.

The first control center 1430-1 may determine control transfer in response to the control transfer start request and may request the second control center 1430-2 to start the control transfer procedure.

The second control center 1430-2 may make a radio link connection preparation request with the UAV 1450 to the second ground station 1440-2 and receive a response. In addition, the second control center 1430-2 may transmit a confirmation message regarding the control transfer procedure start request to the first control center 1430-1. In response to the radio link connection preparation request, the second ground station 1440 - 2 may configure transmission/reception of a channel for handover and prepare a radio link connection with the UAV 1450 .

The first control center 1430-1 may transmit a handover command to the UAV 1450 through the first ground station 1440-1. The UAV 1450 may perform a handover from a channel currently in use to a channel for handover, and transmit a handover completion message to the second ground station 1440-2. Upon receiving the handover complete message, the second ground station 1440-2 may report handover completion to the second control center 1430-2. Upon receiving the handover completion report, the second control center 1430-2 may inform the first control center 1430-1 of completion of the control transfer. Upon receiving control transfer completion, the first control center 1430-1 may notify the first ground station 1440-1 of handover completion. Accordingly, the first ground station 1440-1 may end the transmission/reception operation with the UAV 1450.

In the control transfer procedure, when the first control center (1430-1) requests the second control center (1430-2) to initiate the control transfer, the first control center (1430-1) sends a request to the second control center (1430-2). , security-related setting information currently applied between the first ground station 1440-1 and the UAV 1450 may be delivered together.

The second control center 1430-2 may update the security key based on security-related setting information. The security key may be used for a radio link connection between the second ground station 1440-2 and the UAV 1450. The second control station 1430-2 may provide the second ground station 1440-2 with an updated security key when requesting preparation for a radio link connection with the UAV 1450. In addition, when the second control center 1430-2 confirms the start of the transfer of control authority to the first control center 1430-1, security setting information to be used by the second ground station 1440-2 and the UAV 1450 is also included. can provide The drone station 1450 may set security based on provided security setting information. The first control center 1430-1 may include security setting information in the handover command and provide it to the UAV 1450.

When the first control center 1430-1 and the second control center 1430-2 do not share security settings, the UAV 1450 and the second ground station 1440-2 transmit handover completion immediately after handover. Security may not be applied to messages.

An operation after the second control center 1430-2 receives the handover complete message from the second ground station 1440-2 may be as described with reference to FIG. 13 .

The configuration described above can be used for handover of communication for controlling the UAV that may occur during operation of the UAV and transfer of control authority between control centers controlling the UAV. In addition, the above configurations can be applied to P2P and P2MP type UAV CNPC systems, and when applied to a P2MP type UAV CNPC system, a plurality of UAVs can be supported simultaneously.

The devices described above may be implemented as hardware components, software components, and/or a combination of hardware components and software components. For example, devices and components described in the embodiments may include, for example, a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable gate array (FPGA) , a programmable logic unit (PLU), microprocessor, or any other device capable of executing and responding to instructions. A processing device may run an operating system (OS) and one or more software applications running on the operating system. A processing device may also access, store, manipulate, process, and generate data in response to execution of software. For convenience of understanding, there are cases in which one processing device is used, but those skilled in the art will understand that the processing device includes a plurality of processing elements and/or a plurality of types of processing elements. It can be seen that it can include. For example, a processing device may include a plurality of processors or a processor and a controller. Other processing configurations are also possible, such as parallel processors.

Software may include a computer program, code, instructions, or a combination of one or more of the foregoing, which configures a processing device to operate as desired or processes independently or collectively. You can command the device. Software and/or data may be any tangible machine, component, physical device, virtual equipment, computer storage medium or device, intended to be interpreted by or provide instructions or data to a processing device. , or may be permanently or temporarily embodied in a transmitted signal wave. Software may be distributed on networked computer systems and stored or executed in a distributed manner. Software and data may be stored on one or more computer readable media.

The method according to the embodiment may be implemented in the form of program instructions that can be executed through various computer means and recorded on a computer readable medium. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. Program commands recorded on the medium may be specially designed and configured for the embodiment or may be known and usable to those skilled in computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks and magnetic tapes, optical media such as CD-ROMs and DVDs, and magnetic media such as floptical disks. - includes hardware devices specially configured to store and execute program instructions, such as magneto-optical media, and ROM, RAM, flash memory, and the like. Examples of program instructions include high-level language codes that can be executed by a computer using an interpreter, as well as machine language codes such as those produced by a compiler. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

As described above, although the embodiments have been described with limited examples and drawings, those skilled in the art can make various modifications and variations from the above description. For example, the described techniques may be performed in an order different from the method described, and/or components of the described system, structure, device, circuit, etc. may be combined or combined in a different form than the method described, or other components may be used. Or even if it is replaced or substituted by equivalents, appropriate results can be achieved.

Therefore, other implementations, other embodiments, and equivalents of the claims are within the scope of the following claims.

Claims (33)

delete delete delete delete delete delete delete A method for performing inter-cell handover from a first ground station to a second ground station,
setting a first channel to the second ground station;
measuring a second channel by an UAV and reporting a measurement result to the first ground station;
requesting, by the first ground station, handover to at least one of a control center and a CNPC network based on the measurement result;
transmitting, by the at least one, a measurement signal for handover decision to an UAV;
determining whether the at least one handover is performed; and
Instructing the at least one handover to the UAV based on the determined handover status
including,
The transmission of the measurement signal is determined by the second ground station or the UAV in response to a request for determining a transmission time of the at least one measurement signal.
According to claim 8,
The first channel is a channel for handover, and the second channel is a channel currently in use.
According to claim 8,
In the setting step,
setting a first channel to the UAV and the second ground station;
A handover method comprising a.
According to claim 8.
The step of reporting the measurement result,
Reporting the measurement result when the signal quality of the second channel is equal to or less than a reference value
A handover method comprising a.
According to claim 8,
The command step is
requesting, by the at least one, handover to the second ground station based on the determined handover status;
responding, by the second ground station, to a handover request to the second ground station; and
the at least one commanding a handover to the UAV based on a response from the second ground station;
A handover method comprising a.
According to claim 12,
The step of requesting handover to the second ground station,
providing, by the at least one, security setting information to be used when the second ground station and the UAV communicate with each other;
A handover method comprising a.
According to claim 13,
communicating with the second ground station and the UAV using the security setting information;
A handover method further comprising.
According to claim 8,
setting an initial channel to the UAV and the first ground station to connect a wireless link;
A handover method further comprising.
According to claim 8,
The UAV performs handover to the first channel based on the command and reports handover completion to the at least one.
A handover method further comprising.
According to claim 16,
The step of reporting the handover completion,
transmitting, by the at least one, control communication data to the UAV; and
performing handover to the first channel by the UAV based on the control communication data;
A handover method comprising a.
According to claim 17,
The sending step is
transmitting, by the at least one, the control communication data to the UAV via the second ground station;
A handover method comprising a.
According to claim 16,
The step of reporting the handover completion,
The UAV reporting handover completion to the at least one via the second ground station.
A handover method comprising a.
According to claim 12,
transmitting, by the at least one, information necessary for obtaining synchronization to the second ground station when the at least one requests handover to the second ground station; and
Performing, by the UAV, handover based on information necessary for acquiring the synchronization
A handover method further comprising.
According to claim 8,
The first channel and the second channel are channels for handover.
delete According to claim 21,
The step of reporting the measurement result,
Reporting the measurement result when the signal quality of the first channel and the second channel is better than that of the currently used channel
A handover method comprising a.
According to claim 8,
The step of transmitting the measurement signal,
the at least one requesting the second ground station to determine a measurement signal transmission time; and
Determining, by the second ground station, transmission of the measurement signal in response to the request for determining the measurement signal transmission time
A handover method comprising a.
According to claim 24,
The step of determining the signal transmission for measurement,
determining, by the second ground station, transmission of the measurement signal based on downlink channel information of the UAV
A handover method comprising a.
According to claim 8,
The step of transmitting the measurement signal,
the at least one requesting the UAV to determine a measurement signal transmission time point; and
Determining, by the UAV station, transmission of the measurement signal in response to a request for determining the measurement signal transmission time;
A handover method comprising a.
The method of claim 26,
The step of determining the signal transmission for measurement,
Determining transmission of the measurement signal using GNSS location information for the UAV or received signal strength for the first ground station
A handover method comprising a.
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