KR20180054393A

KR20180054393A - Method for contacting the channel of unmanned aerial vehicle(uav) control and non-payload communications(cnpc) system in case of radio link failure

Info

Publication number: KR20180054393A
Application number: KR1020160175390A
Authority: KR
Inventors: 홍태철; 김희욱; 임광재
Original assignee: 한국전자통신연구원
Priority date: 2016-11-14
Filing date: 2016-12-21
Publication date: 2018-05-24

Abstract

A channel access method of a UAV CNPC system in case of a radio link failure is disclosed. A channel access method of a UAV CNPC system according to an embodiment includes a step of a UAV monitoring a radio link based on a received signal strength or a CRC result, and in the case of a radio link failure, a step of the UAV attempting to re- And in the case of failure of the reconnection of the radio link, releasing the radio link by the unmanned aerial station and ending the transmission / reception operation.

Description

TECHNICAL FIELD The present invention relates to a method for accessing a UWB CNPC system in a wireless link failure,

The following embodiments relate to a channel access method of a UAV CNPC system in case of a radio link failure.

It includes all the components necessary for the entire flight, including unmanned aerial vehicle (UAV), pilotless aircraft or drone, as well as a control communication system for takeoff / cruising, flight control, landing / Unmanned Aircraft Systems (UAS) or Remotely Piloted Aircraft Systems (RPAS).

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

A mission data link is a link for carrying data related to mission performance and is generally broader than a CNPC data link. On the other hand, the CNPC link is composed of a pilot / ATC relay link and a UAS control link as a link for conveying data related to UAV flight control, UAS status monitoring, and CNPC link management. The pilot / ATC relay link is a communication link for relaying voice and data between the ATC and the pilot through the UAV, and the UAS control link is used to transmit safety control related information between the pilot and the UAV Link. In case of UAS control link, it can be divided into Telecommand (TC) link and Telemetry (TM) link. TC link can be classified into flight control information, all UAV control information required for safety flight Is the uplink that transmits from the ground pilot to the UAV, and the TM link is the UAV position, altitude, speed, UAS system operation mode and status, navigation assistance data, detection and avoidance related trace, weather radar, To the pilot of the aircraft.

The frequency for the unmanned terrestrial CNPC link is mainly considered as the C (5030-5091 MHz) band allocated to the new dedicated band in WRC-12, and the L (L) 960-1164 MHz) bands may be considered in the aeronautical mobile service. In the C band, the effect of frequency interference with the existing system and the multipath delay spread are small. On the other hand, there is a disadvantage that the directional antenna must be considered for ensuring the link margin and the Doppler effect is five times larger than the L band. On the other hand, the low-frequency band distributed to other aeronautical mobile services such as the L-band has better propagation characteristics than the C-band (L band has 14 dB lower propagation loss than the C band) Equipment, ADS-B (Automatic Dependent Surveillance-Broadcast), and TACAN (Tactic Air Navigation System) are operated in a congested manner, there is a problem in securing the frequency and a large multipath delay spread. Therefore, it is expected that the pre-established C band will be considered as the base link of the terrestrial CNPC and the lower frequency band (eg L or UHF band) will be used to increase the CNPC link availability for unmanned safety navigation. Of course, you can use them in reverse or independently.

Next, terrestrial CNPC link connection types are P2P (Point-to-Point) type and P2MP (Point-to-MultiPoint) type. The P2P type is a concept in which one GRS forms a data link with one UA, which is a type that has been mainly considered in a conventional unmanned aerial vehicle system. On the other hand, in the P2MP type, one GRS forms a data link with a plurality of UAs. In the P2MP type, the GRSs are connected to the network to support the GRS handover. Both P2P type and P2MP type GRS can be connected to the network to provide continuous communication service for UAV control such as GRS handover, or it can be constructed as a single GRS type. Typically, P2P type is built as a single GRS type, and P2MP type is expected to be network based GRS construction. The network-based P2MP type, which can form a communication link with a large number of UAVs at the same time, is expected to be considered as a next generation CNPC link, and the related technology of the P2MP type UAS CNPC system is still insufficient.

In addition, in order to operate the existing P2P type UAS CNPC system, a channel for CNPC must be allocated. In the conventional method, when the UAS CNPC system is registered in the Spectrum Authority (SA), the channel is fixed for a long time The channel assigned to a specific UAS CNPC system is difficult to use in another UAS CNPC system.

Therefore, it is indispensable for the UAV CNPC system to operate efficiently in order to efficiently utilize communication frequency resources for UAV control, which can efficiently operate a large number of UAVs in a limited UAV control dedicated frequency band, for stable operation of UAV and demand expansion of UAV do.

In order to stabilize operation of UAV and increase demand of UAV, it is necessary to design and operate UAV control communication system that can efficiently operate a large number of UAVs in a limited frequency range of UAV control. The frequency bureau does not allocate a specific frequency to a specific CNPC system in a fixed manner. Instead, the frequency bureau manages the frequency in real time and dynamically allocates it only when the UAS CNPC system is operated. And the UAV CNPC system should support such dynamic channel allocation and management.

There is a need for a wireless link failure determination and an operation method at the time of a radio link failure in a communication system for UAV control suited to such a dynamic channel allocation and management method. The present invention proposes a wireless link failure determination and operation method considering a channel allocation and management method dynamically performed in a frequency bureau.

According to an embodiment of the present invention, there is provided a method for connecting a UAV to a UAV, comprising: monitoring a wireless link based on a received signal strength or a CRC result by the UAV; attempting reconnection of a wireless link by the UAV in case of a wireless link failure; In the case of failure of the reconnection of the radio link, the unmanned aerial station releases the radio link and terminates the transmission / reception operation.

Wherein the step of monitoring includes the steps of: the UAV measuring the received signal strength using a preamble of a received signal; and determining that the UAV does not fail if the received signal strength is lower than a reference value .

Wherein the determining step comprises the steps of: setting a timer for determining the radio link failure if the received signal strength is continuously equal to or less than the reference value; Determining that the radio link failure is not a case where the radio link failure occurs consecutively if the received signal strength is equal to or greater than the reference value, and if the received signal strength is not equal to or greater than the reference value before the timer ends the operation, It may be determined to be a failure.

The step of determining that the radio link failure is not includes a step of releasing the timer.

Wherein the step of monitoring includes the steps of: determining whether a CRC of the received signal is an error of the received signal by the UAV; determining whether the UAV has failed if the error exists; .

The method of claim 1, wherein the step of determining comprises: setting a timer for determining the failure of the radio link if the error occurs consecutively; and if the normal signal is measured more than a reference number before terminating the timer, And determining that the radio link is failed if the normal signal is not measured more than the reference number before the timer ends the operation.

The method of claim 1, wherein the step of attempting reconnection comprises the steps of: reporting, in the case of the radio link failure, to the flight controller of the UAV; attempting reconnection of the UAV by the UAV, Lt; / RTI >

The step of attempting reconnection or attempting landing may include terminating the transmission / reception operation when the UAV attempts to land.

Wherein the step of attempting reconnection or attempting landing comprises the steps of: establishing a channel for unmanned communication to the ground station when the unmanned person attempts to reconnect; and transmitting the channel to the ground station and the unmanned aerial vehicle based on the unmanned communication channel And performing an initial connection.

A ground station access method according to an embodiment includes a step in which a ground station monitors a radio link based on a CRC result, and in the case of a radio link failure, the ground station releases the radio link and ends the transmission / reception operation.

Wherein the step of monitoring comprises the steps of: the ground station determining a CRC result of a received signal to determine whether the received signal is erroneous; and if the error exists, determining that the ground station determines the radio link failure .

The terminating may include, in the case of the radio link failure, the ground station reporting the radio link failure.

The method comprises the steps of: setting a channel for unmanned communication to the ground station when the unmanned person attempts to reconnect; setting the channel based on the channel for unmanned communication by the ground station and the unmanned communication station and performing initial connection .

FIG. 1 illustrates an example of a relationship and information exchange with a peripheral system for stable operation of a UAV in a UAV CNPC system according to an exemplary embodiment.
Figure 2 shows another example of the relationship and information exchange between peripheral systems for stable operation of UAV in a UAV CNPC system according to an embodiment.
Figure 3 shows an example of a block diagram of a UAV CNPC system,
4 is a view for explaining an example of the operation of the UAV CNPC system in case of a radio link failure.
5 is a view for explaining an example of the operation of the control center when the radio link fails.
6 is a view for explaining an example of the operation of an unmanned aerial vehicle station when a radio link fails.
7 is a view for explaining an example of the operation of a ground station in the case of a radio link failure.

It is to be understood that the specific structural or functional descriptions of embodiments of the present invention disclosed herein are presented for the purpose of describing embodiments only in accordance with the concepts of the present invention, May be embodied in various forms and are not limited to the embodiments described herein.

Embodiments in accordance with the concepts of the present invention are capable of various modifications and may take various forms, so that the embodiments are illustrated in the drawings and described in detail herein. However, it is not intended to limit the embodiments according to the concepts of the present invention to the specific disclosure forms, but includes changes, equivalents, or alternatives falling within the spirit and scope of the present invention.

The terms first, second, or the like may be used to describe various elements, but the elements should not be limited by the terms. The terms may be named for the purpose of distinguishing one element from another, for example without departing from the scope of the right according to the concept of the present invention, the first element being referred to as the second element, Similarly, the second component may also be referred to as the first component.

It is to be 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, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between. Expressions that describe the relationship between components, such as "between" and "between" or "neighboring to" and "directly adjacent to" should be interpreted as well.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. It will be understood that, in this specification, the terms "comprises ", or" having ", and the like are to be construed as including the presence of stated features, integers, But do not preclude the presence or addition of steps, operations, elements, parts, or combinations thereof.

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 this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the meaning of the context in the relevant art and, unless explicitly defined herein, are to be interpreted as ideal or overly formal Do not.

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 embodiments. Like reference symbols in the drawings denote like elements.

FIG. 1 illustrates an example of a relationship and information exchange with a peripheral system for stable operation of a UAV in a UAV CNPC system according to an exemplary embodiment.

Referring to FIG. 1, a UAV CNPC system 10 includes a spectrum authority (SA) 110, an air traffic control (ATC) 120, a ground control equipment 130, a CNPC A ground CNPC radio system 140, and a CNPC airborne CNPC radio system 150.

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

In order to operate the P2P unmanned CNPC system, the control center 130 can request the channel to the SA 110 and receive the channel allocation (K1) from the SA 110.

Next, the control center 130 transmits the ground / unmanned CNPC radio channel assignment information and the information F1 including the state information G1 and the communication data between the ATC 120 and the UAV control data to the CNPC ground station system 140 (H1).

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

The CNPC unmanned aerial station system 150 may transmit the information A1 including the communication data with the ATC 120 and the unmanned control data to the CNPC ground station system 140. The CNPC ground station system 140 may transmit the information F1 received from the CNPC UAV system 150 and the CNPC radio channel allocation information and the status information G1 to the control station 130 via the wired or wireless network H1 . The characteristics of the UAV CNPC system 10 will be described below.

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

1) The UAV CNPC system 10 includes a plurality of ground stations and an unmanned aerial station, and each ground station and the unmanned aerial station can form a one-to-one communication link.

2) If the UAV CNPC system 10 is a standalone system, the UAV CNPC system 10 can extend the coverage by switching the ground station (GRS) of the control station and transferring control.

3) The UAV CNPC system 10 implements an FDMA-based ground station and can support multiple P2P type UAVs in a single ground station.

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

1) The UAV CNPC system 10 can operate on an FDMA channel in uplink (ground station -> unmanned station) and downlink (unmanned station -> ground station).

2) The UAV CNPC system 10 can support simultaneous transmission and reception in dual band channels (e.g., L band and C band).

3) The UAV CNPC system 10 may support multiple channel bandwidths (e.g., four Data Classes (DC1) with 30/60/90/120 kHz).

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

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

6) The UAV 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 other than channel reallocation and handover.

Figure 2 shows another example of the relationship and information exchange between peripheral systems for stable operation of UAV in a UAV CNPC system according to an embodiment.

2, the UAV CNPC system 20 includes an SA 210, an ATC 220, a control station 230-1 to 230-N, a CNPC ground station system 240, and a CNPC UAV system 250-1 To 250-3). The UAV CNPC system 20 may be a UAV CNPC system that controls the UAVs 290-1 through 290-3 in a Point-to-Multi-Point (P2MP) type. The UAVs 290-1 through 290-3 may include at least one of a configuration 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, 110, the ATC 120, the control station 130, the CNPC ground station system 140, and the CNPC unmanned aerial station system 150 may be substantially the same in construction and operation.

Although FIG. 2 shows three CNPC unmanned aerial vehicle systems 250-1 to 250-3 and three unmanned aerial vehicles 290-1 to 290-3 for convenience of explanation, it is not necessarily limited thereto, And can be implemented as a plurality of UAVs.

In order to operate the P2MP type UAV CNPC system, the control stations 230-1 to 230-N can make a channel request to the SA 210 and receive the channel assignment K1 from the SA 210. [

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

The CNPC UAV system 250-1 to 250-3 transmits information (A1 to An) including communication data with the ATC 120 relayed from the VHF / UHF Radio and UAV control data to the CNPC ground station system 240 . The CNPC ground station system 240 transmits information (F1 to Fn), CNPC radio channel assignment information, and status information (G1 to Gn) received from a plurality of CNPC UAVs 250-1 to 250-3 to a wired / (H1 to Hn) to the corresponding control stations 230-1 to 230-N.

The control communication service for safe operation provided by the UAV CNC system 20 between the control stations 230-1 to 230-N and the UAVs 290-1 to 290-3 is performed in the case of uplink or downlink can be different. For example, in the case of the uplink, the control communication service for safe operation includes at least one of Telecommand information, ATC Relay information, and NavAid setting information. In the downlink case, the control communication service for safe operation includes telemetry information, ATC relay Information, NavAid information, DAA Target information, Weather Radar information, Safety take-off landing video information, and Emergency video information. The ATC Relay information may include ATC voice and data relay information.

The UAV CNPC system 20 can define and provide various types of service classes to provide various services according to the 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 case of the uplink. Also, 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 a service class as shown in Table 2 in the case of downlink.

The services provided by the CNPC UAV stations 250-1 to 250-3 include telecommand information (uplink, ground station, and unmanned aerial station) and telemetry information (downlink , Unmanned aerial station -> ground station). 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, depending on the capabilities of the terrestrial and stationary stations and the allocated channel capacity or bandwidth.

The CNPC UAV system 250-1 to 250-3 transmits video services (safety takeoff and landing video information and / or emergency video information) that can be considered in takeoff and landing and emergency situations to a single band of a separate downlink channel For example, the C-band for controlling the UAV). That is, the CNPC UAV system 250-1 to 250-3 transmits one of the Service Classes of Service Classes 1 to 4 and one of the Service Classes 5 to 6 to the C-band Lt; RTI ID = 0.0 > channel < / RTI >

The UAV CNPC system 20 can operate in a dual band so that the link meets 99.999% usage. For example, the CNPC unmanned aerial platform systems 250-1 through 250-3 may operate in the dual band of the C and L bands allocated for UAV control. The UAV CNPC system 20 can transmit the same information or other information in the dual band. When the CNPC UAV system 250-1 to 250-3 transmit the same information, the signal level diversity gain between the L and C bands can be obtained in the physical layer, and the C band and L band A different bandwidth can be allocated from the SA 210 to the mobile station.

At this time, the C band can be utilized for the UAV CNPC with the entire frequency band of 61 MHz as the UAV exclusive frequency band. For example, the CNPC UAV system 250-1 to 250-3 can transmit at least one of TC / TM data, ATC relay information, DAA target information, and Weather radar information in the C band.

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

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

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

2) When the UAV CNPC system 20 is connected to the network, the UAV CNPC system 20 can extend the coverage through inter-terrestrial handover.

3) The UAV CNPC system 20 can implement a TDM-based ground station to support multiple UAVs in one ground station.

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

1) The UAV CNPC system 20 can operate on the TDM channel in the uplink (ground station -> unmanned aerial station).

2) The UAV CNPC system 20 can allocate different TDM time slots for each unmanned station and distinguish the unmanned station according to the TDM time slot.

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

4) The UAV CNCP system 20 can flexibly change the number and location of slots allocated to the UAV communicating with the corresponding ground station, thereby supporting multiple UAVs simultaneously and efficiently supporting channel change in the cell.

5) The UAV CNPC system 20 can operate on the FDMA channel in the downlink (unmanned station -> ground station).

6) The UAV CNPC system 20 can support simultaneous transmission and reception in dual band channels (e.g., L band and C band).

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

8) The UAV CNPC system 20 can support different TDM time slot numbers according to the uplink channel bandwidth. For example, the UAV CNPC system 20 can support three slots for 90 kHz, six slots for 180 kHz, and 24 slots for 720 kHz.

9) The UAV CNPC system 20 can support the number of different channel bandwidths per link direction and band. For example, the UAV CNPC system 20 can support 90/180/270/360/450/540/630/720 kHz in the uplink and 30/40/90/120 kHz in the downlink have.

10) The UAV 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 can operate in a fixed channel other than channel reassignment and handover.

The radio link between the UAV and the ground station may degrade in quality depending on the situation and eventually cause a call drop. This can be called a radio link failure. Hereinafter, a radio link failure determination and a radio link failure operation in the UAV CNPC system will be described.

FIG. 3 is a block diagram of a UAV CNPC system, FIG. 4 is a view for explaining an example of the operation of a UAV CNPC system in case of a radio link failure, and FIG. 1 is a view for explaining an example.

3 to 5, the UAV CNC system 30 includes an SA 310, a control station or CNPC network 330, a ground station 340, an unmanned aerial station 350, and a UAV 390. The UAV 390 includes a flight controller (Flight Control) 391 for controlling the flight.

The flight controllers 491 and 591, the UAVs 450 and 550, the ground stations 440 and 540, and the control center or CNPC networks 430 and 530 shown in Figures 4 and 5 are connected to the flight controller 391, the UAV 350, the ground station 340, and the control station or the CNPC network 330, as shown in FIG. The operation of the UWB CNPC system 30 will be described using the member numbers in Fig.

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 a handover using the identity of the control station and the ground station 340.

The control station or the CNPC network 330 may establish a channel for unmanned communication to the ground station 340. At this time, the control center or the CNPC network 330 may be allocated a channel for UAV communication from the SA 310. The control station or the CNPC network 330 may establish a channel to the ground station 340 based on the channel for UAV communication. The UAV 350 and the ground station 340 may establish a channel according to a UAV communication channel and be wirelessly linked through an initial connection. The UAV 350 and the ground station 340 may continue to monitor the channel in use after the wireless link connection. Thus, the UAV 350 and the ground station 340 can determine whether the wireless link has failed based on the monitoring result.

In the event of a radio link failure, the control center or CNPC network 330 may operate differently according to the contingency plan set in the UAV. In the event of a radio link failure, the UAV may be configured to attempt reconnection (reconnection) or attempt landing. For example, a UAV may attempt to reconnect (reconnect) by performing a turn at high altitude, etc., or to land immediately to wait for an action such as a check.

If the URI is set to attempt to reconnect (reconnect) in the event of a radio link failure, the control center or CNPC network 330 may be reassigned from the SA 310. The control center or CNPC network 330 may establish a channel in the ground station 340 based on the reallocated channel. The unmanned aerial station 350 and the ground station 340 may establish a channel according to the reallocated channel, and may be wirelessly linked through the initial connection. That is, the UAV 350 and the ground station 340 may attempt to reconnect according to the reallocated channel.

In the event of a radio link failure, if the UAV is set to attempt landing, the control center or the CNPC network 330 may not perform other operations for the radio link connection. The control center or the CNPC network 330 may wait for the next operation.

The operation of the UAV 350 and the ground station 340 when a radio link failure occurs will be described in detail with reference to Figs. 6 and 7. Fig.

6 is a view for explaining an example of the operation of an unmanned aerial vehicle station when a radio link fails.

Referring to FIG. 6, the UAV 650 may perform radio link monitoring on a channel in use to determine whether a radio link fails. The UAV 650 can determine whether the wireless link fails based on the data reception result according to the monitoring.

For example, the UAV 650 can determine whether a wireless link fails based on a received signal strength of a received data signal and / or a sub-frame according to a CRC (Cyclic Redundancy Check) result. The UAV 650 can measure a received signal strength using a preamble of a received data signal. For example, the UAV 650 may determine whether a wireless link fails by checking whether an error exists in a subframe.

The UAV 650 may operate a timer for determining a radio link failure if the CRC result is erroneous or the received signal strength of the data signal is less than or equal to the reference value. The CRC result may mean a signal or a subframe. In addition, the UAV 650 may operate a timer for determining a radio link failure if the CRC result is continuously in error or the received signal strength of the data signal is below a reference value. For example, if the CRC result is n consecutive times or if the received signal strength of the n consecutive data signals is less than or equal to the reference value, a timer for radio link failure determination can be operated.

The UAV 650 may determine that the CRC result is not successful if the CRC result is successful or the received signal strength of the data signal is equal to or greater than the reference value before the timer ends the operation. At this time, the UAV 650 may determine that the radio link failure is not a failure if the CRC result and / or the received signal strength are consecutive before the timer ends the operation. For example, the UAV 650 may determine that the CRC result is not a wireless link failure if the CRC result is successive m successes, or if the received signal strength of the data signal is equal to or greater than the consecutive m times reference value have.

That is, if the CRC result does not succeed m times successively before the timer ends the operation, or if the received signal strength of the data signal is not equal to or greater than the m reference value consecutively, the wireless link failure It can be judged.

In case of a radio link failure, the UAV 650 may report a radio link failure to the flight controller 691. In response to the radio link failure report, the flight controller 691 may control that the UAV tries to reconnect (reconnect) or attempt to land.

The unmanned aerial station 350 and the ground station 340 may retry the wireless link connection through reconnection. For example, the UAV 690 may attempt to reconnect (reconnect) with the ground station 650 after a radio link failure report or in response to a command from the flight controller 691. [

If the reconnection attempt fails, the UAV 690 may perform operations under the control of the control center or the CNPC network 630. That is, the control station or the CNPC network 630 can control the UAV 690 according to the emergency situation plan set in the UAV. The emergency plan may include channel reassignment or termination of the transmit and receive operations.

The control center or the CNPC network 630 may reassign the channel from the SA to the ground station 640. And the operation of setting the channel based on the channel reallocated by the unmanned aerial station 650 and the ground station 640 are as described above.

When the UAV 650 and the ground station 640 fail to reconnect (reconnect) the wireless link, the UAV 650 sends a radio link release to the ground station 640 and releases the wireless link to the flight controller 691 Can be reported. The unmanned aerial station 650 can terminate the transmission / reception operation according to the radio link release.

7 is a view for explaining an example of the operation of a ground station in the case of a radio link failure.

7, the ground station 740 can receive a signal from the unmanned aerial station 750 until the unmanned aerial station 750 finishes the transmission / reception operation.

The ground station 740 may perform radio link monitoring on the channel in use to determine whether the radio link failed. The ground station 740 can determine whether the radio link fails based on the data reception result according to the monitoring.

The ground station 740 can determine whether the radio link fails based on the subframe according to the CRC result. If the ground station 740 fails to receive a valid signal (e.g., a subframe without a CRC result error), the ground station 740 may operate a timer for radio link failure determination. At this time, the timer may be set to be longer than the timer operated by the UAV 650 described in FIG.

The ground station 740 may determine that it is not a radio link failure if the timer has received a valid signal (e.g., a subframe without a CRC result error) before terminating the operation. That is, if the ground station 740 fails to receive a valid signal (e.g., a subframe without a CRC result error) before the timer ends the operation, the ground station 740 may determine the radio link failure.

In case of a radio link failure, the ground station 740 may report a radio link failure to the control center or the CNPC network 730. The ground station 740 may transmit the radio link release to the UAV 750 and terminate the transmission / reception operation for the failed UAV.

If the unsuccessful UAV attempts to reconnect (reconnect) to the UAV 750, the control center or CNPC network 730 may re-establish the UAV communication channel. The ground station 740 may resume transmitting and receiving operations.

The above-described configurations can perform an initial connection of the ground station and the UAV by using the frequencies allocated through the SA. Also, even if the UAV does not know the information assigned, it is possible to find the assigned frequency and perform the connection. The above-mentioned UAV CNPC system can be flexibly extended and can be used in the P2P type or P2MP type. When the UAV CNPC system is used for the P2MP type, it can support multiple UAVs at the same time.

The apparatus described above may be implemented as a hardware component, a software component, and / or a combination of hardware components and software components. For example, the apparatus and components described in the embodiments may be implemented within a computer system, such as, 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), a microprocessor, or any other device capable of executing and responding to instructions. The processing device may execute an operating system (OS) and one or more software applications running on the operating system. The processing device may also access, store, manipulate, process, and generate data in response to execution of the software. For ease of understanding, the processing apparatus may be described as being used singly, but those skilled in the art will recognize that the processing apparatus may have a plurality of processing elements and / As shown in FIG. For example, the processing unit may comprise a plurality of processors or one processor and one controller. Other processing configurations are also possible, such as a parallel processor.

The software may include a computer program, code, instructions, or a combination of one or more of the foregoing, and may be configured to configure the processing device to operate as desired or to process it collectively or collectively Device can be commanded. The software and / or data may be in the form of any type of machine, component, physical device, virtual equipment, computer storage media, or device , Or may be permanently or temporarily embodied in a transmitted signal wave. The software may be distributed over a networked computer system and stored or executed in a distributed manner. The software and data may be stored on one or more computer readable recording media.

The method according to an embodiment may be implemented in the form of a program command that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions to be recorded on the medium may be those specially designed and configured for the embodiments or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. 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.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. For example, it is to be understood that the techniques described may be performed in a different order than the described methods, and / or that components of the described systems, structures, devices, circuits, Lt; / RTI > or equivalents, even if it is replaced or replaced.

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

Claims

Monitoring the wireless link based on the received signal strength or the CRC result;
In case of a radio link failure, the unlicensed station attempts to reconnect the radio link; And
In the case of failure of the reconnection of the radio link, the unlicensed station releases the radio link and ends the transmission / reception operation
And an unmanned station access method.

The method according to claim 1,
Wherein the monitoring comprises:
Measuring the received signal strength using the preamble of the received signal; And
If the received signal strength is equal to or less than a reference value, determining that the URI determines the wireless link failure
And an unmanned station access method.

3. The method of claim 2,
Wherein the determining step comprises:
Setting a timer for determining the radio link failure if the received signal strength is continuously equal to or less than the reference value;
Determining that the radio link failure does not occur when the received signal strength is continuously equal to or greater than the reference value before the timer ends the operation; And
If the received signal strength is not equal to or greater than the reference value before the timer ends the operation,
And an unmanned station access method.

The method of claim 3,
The method of claim 1,
Releasing the timer
And an unmanned station access method.

The method according to claim 1,
Wherein the monitoring comprises:
Determining whether a CRC of the received signal is an error of the received signal by the UAV; And
If the error exists, determining that the URI determines the wireless link failure
And an unmanned station access method.

6. The method of claim 5,
Wherein the determining step comprises:
Setting a timer for determining the radio link failure if the error occurs consecutively;
Determining that the wireless link fails if the normal signal is measured more than the reference number before the timer ends the operation; And
Determining that the radio link is failed if the normal signal is not measured more than the reference number before the timer ends the operation;
And an unmanned station access method.

The method according to claim 6,
The method of claim 1,
Releasing the timer
And an unmanned station access method.

The method according to claim 1,
Wherein the attempting to reconnect comprises:
Reporting, in the case of the radio link failure, the UAV to a flight controller; And
A step in which the UAV attempts to reconnect the air link or attempts landing according to the control of the flight controller
And an unmanned station access method.

9. The method of claim 8,
The step of attempting to reconnect, or attempting landing,
If the UAV attempts to land, terminating the transmission / reception operation
And an unmanned station access method.

9. The method of claim 8,
The step of attempting to reconnect, or attempting landing,
Setting a channel for UAV communication to the ground station when the UAV attempts to reconnect; And
The ground station and the unmanned aerial station set a channel based on the URI communication channel, and perform an initial connection
And an unmanned station access method.

The ground station monitoring the wireless link based on the CRC result; And
In the case of a radio link failure, the ground station releases the radio link and ends the transmission / reception operation
To the ground station.

12. The method of claim 11,
Wherein the monitoring comprises:
Determining whether the received signal is erroneous by checking the CRC result of the received signal by the ground station; And
If the error exists, determining that the radio link failure is caused by the ground station
To the ground station.

13. The method of claim 12,
Wherein the determining step comprises:
Setting a timer for determining the radio link failure if the error occurs consecutively;
Determining that the wireless link fails if the normal signal is measured more than the reference number before the timer ends the operation; And
Determining that the radio link is failed if the normal signal is not measured more than the reference number before the timer ends the operation;
To the ground station.

14. The method of claim 13,
The method of claim 1,
Releasing the timer
To the ground station.

12. The method of claim 11,
Wherein the terminating comprises:
In the case of the radio link failure, the ground station reports the radio link failure
To the ground station.

12. The method of claim 11,
Setting a channel for UAV communication to the ground station when the UAV attempts to reconnect; And
The ground station and the unmanned aerial station set a channel based on the URI communication channel, and perform an initial connection
To the ground station.