KR20230027967A - Method and apparatus for supporting unmanned aerial vehicle communications - Google Patents

Abstract

A communication method performed by a first communication node in a communication system is disclosed. A communication method performed by a terrestrial radio station comprises the following steps of: transmitting an uplink channel including a medium access control (MAC) protocol data unit (PDU) to an uplink slot; allocating one or more downlink slots to one or more unmanned aerial vehicles receiving the uplink channel; and receiving a downlink channel including information generated based on information included in the uplink channel through the one or more downlink slots.

Description

Method and apparatus for supporting UAV communication {METHOD AND APPARATUS FOR SUPPORTING UNMANNED AERIAL VEHICLE COMMUNICATIONS}

The present invention relates to UAV communication technology, and more particularly, to a frame structure and communication method for supporting UAV communication.

In a cellular communication network, a user equipment may generally transmit and receive a data unit through a base station. For example, when there is a data unit to be transmitted to the second terminal, the first terminal may generate a message including the data unit to be transmitted to the second terminal, and send the generated message to the first base station to which it belongs. can transmit The first base station can receive a message from the first terminal and can confirm that the destination of the received message is the second terminal. The first base station may transmit the message to the second base station to which the second terminal, which is the confirmed destination, belongs. The second base station may receive a message from the first base station and may confirm that the destination of the received message is the second terminal. The second base station may transmit a message to the second terminal, which is the confirmed destination. The second terminal may receive a message from the second base station and obtain a data unit included in the received message.

On the other hand, in order to perform the transmission and reception procedure of the data unit described above between the UAV and the ground or UAV, a communication method supporting both control data of the UAV requiring high reliability and data communication for missions requiring broadband may be required. .

Mobile communication technology can be considered as a main communication link to control UAVs for stable operation and mission performance of disaster policing UAVs to improve public safety through disaster public safety prevention and response using UAVs and to transmit mission data. However, mobile communication technology may also have a problem in that communication is disconnected outside the coverage of the existing mobile communication network, such as in the mountains and the sea. Considering that UAVs should be able to be operated in a disaster and public order situation anytime and anywhere in Korea, a secondary communication link for stable control and mission performance of UAVs may be essential even in areas where mobile communication of the main communication link is unavailable.

Accordingly, in Korea, the C-band frequency has been distributed to the licensed frequency band for UAV control and missions for stable operation and expansion of UAV operation. On the other hand, the 5091-5150 MHz band was allocated for domestic use in the C band for mission communication.

In the C band, unlike control communication, in the case of mission communication, optimized technology development and standardization have not been carried out. Therefore, it is necessary to derive the optimal communication method for mission communication in the C band considering the UAV operation scenario.

An object of the present invention to solve the above problems is to provide a communication method and apparatus for control and mission data between an UAV and a ground or UAV.

A communication method performed by a terrestrial radio station according to a first embodiment of the present invention for achieving the object includes transmitting an uplink channel including a medium access control (MAC) protocol data unit (PDU) in an uplink slot. Allocating one or more downlink slots to one or more UAVs receiving the uplink channel, and assigning a downlink channel including information generated based on information included in the uplink channel to the one or more downlink slots It includes the step of receiving through the.

Here, in the step of transmitting the uplink channel including the MAC PDU in the uplink slot, when a plurality of UAVs including a first UAV and a second UAV communicate with the terrestrial radio station, the first MAC PDU and Multiplexing a second MAC PDU, wherein the first MAC PDU and the second MAC PDU belong to the MAC PDU, the first MAC PDU includes control information for a first UAV, and wherein the first MAC PDU includes control information for a first UAV; The 2 MAC PDU may include control information for the second UAV.

Here, the allocating one or more downlink slots includes allocating a downlink slot A for the first UAV when a plurality of UAVs including a first UAV communicate with the terrestrial radio station. And, the downlink slot A belongs to the one or more downlink slots and can be used to receive the downlink channel from the first UAV.

Here, the step of allocating a downlink slot B for a second UAV among the plurality of UAVs, wherein the DL slot B belongs to the one or more DL slots, and the downlink slot B belongs to the one or more UAVs, and the downlink slot B from the second UAV It can be used to receive link channels.

Here, information indicating whether to transmit a subframe composed of the uplink slot and the one or more downlink slots may be received through higher layer signaling.

Here, the subframe includes one or more guard intervals, and the guard interval may be configured to prevent “interference between uplink transmission and downlink transmission” or “interference between downlink transmissions”.

Here, the subframe includes one or more SC-FDE (single carrier-frequency domain equalization) preamble blocks, and the uplink slot and the one or more downlink slots each include one or more SC-FDE pilots. blocks and one or more SC-FDE data blocks, and the SC-FDE pilot blocks may be arranged considering multipath fading.

To achieve the object, a communication method performed by a first UAV according to a second embodiment of the present invention includes receiving an uplink channel through an uplink slot, multiplexing a first MAC PDU and a second MAC PDU to Generating one MAC PDU and transmitting a downlink channel including the multiplexed MAC PDU in one or more downlink slots, wherein the first MAC PDU corresponds to information included in the uplink channel and the type of information included in the first MAC PDU is different from the type of information included in the second MAC PDU.

Here, the first MAC PDU may include control information, and the second MAC PDU may include task information.

Here, in the step of transmitting the downlink channel in one or more downlink slots, when a plurality of UAVs including the first UAV and the second UAV communicate with the terrestrial radio station, through the downlink slot A. Transmitting the downlink channel, and downlink slot B other than the downlink slot A may be used for transmission in the second UAV.

A terrestrial radio station according to a third embodiment of the present invention for achieving the object includes a processor, a memory that communicates electronically with the processor, and instructions stored in the memory. and, when the commands are executed by the processor, the commands are one in which the terrestrial radio station transmits an uplink channel including a MAC PDU in an uplink slot, and sends one or more UAVs receiving the uplink channel. Allocate one or more downlink slots, and cause a downlink channel including information generated based on information included in the uplink channel to be received through the one or more downlink slots.

Here, when the uplink channel including the MAC PDU is transmitted in an uplink slot, the commands are the commands for the terrestrial radio station to perform communication with the terrestrial radio station by a plurality of UAVs including a first UAV and a second UAV. case, operate to cause multiplexing of a first MAC PDU and a second MAC PDU, wherein the first MAC PDU and the second MAC PDU belong to the MAC PDU, and the first MAC PDU is for a first UAV and control information, and the second MAC PDU may include control information for the second UAV.

Here, in case of allocating the one or more downlink slots, the instructions are performed by the terrestrial radio station when a plurality of UAVs including the first UAV communicate with the terrestrial radio station, the downlink slot for the first UAV. A, wherein the downlink slot A belongs to the one or more downlink slots and may be used for receiving the downlink channel from the first UAV.

wherein, cause allocation of a downlink slot B for a second UAV of the plurality of UAVs, wherein the DL slot B belongs to the one or more DL slots and the downlink slot B from the second UAV It can be used to receive link channels.

Here, information indicating whether to transmit a subframe composed of the uplink slot and the one or more downlink slots may be received through higher layer signaling.

According to the present invention, a frame structure capable of simultaneous transmission of data for control and mission of the UAV can be proposed for the UAV communication system. That is, if a frame structure capable of simultaneous transmission is set while satisfying the requirements for control and mission data according to embodiments, communication between the UAV and the ground or between UAVs can be simultaneously supported without interference. Therefore, the performance of the UAV communication system can be improved.

1 is a conceptual diagram illustrating a first embodiment of a communication system.
2 is a block diagram showing a first embodiment of a communication node constituting a communication system.
3 is a conceptual diagram showing a first embodiment of a frame structure of an UAV communication system.
4 is a conceptual diagram illustrating a first embodiment of a subframe structure when a bandwidth is 20 MHz in an UAV communication system.
5 is a conceptual diagram illustrating a first embodiment of a subframe structure for supporting Time Division Duplex (TDD), air-to-air (A2A), and air-to-ground (A2G) communications in an UAV communication system.
6 is a conceptual diagram illustrating a first embodiment of single carrier-frequency domain equalization (SC-FDE) pilot and SC-FDE data block arrangement in a slot in an UAV communication system.
7 is a conceptual diagram illustrating a first embodiment of a configuration of an SC-FDE block within a slot in an UAV communication system.
8 is a flowchart illustrating a first embodiment of a procedure for transmitting and receiving data between a UAV and a terrestrial radio station within one subframe in an UAV communication system.

Since the present invention can make various changes and have various embodiments, specific embodiments are illustrated in the drawings and described in detail. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. These terms are only used for the purpose of distinguishing one component from another. For example, a first element may be termed a second element, and similarly, a second element may be termed a first element, without departing from the scope of the present invention. The terms and/or include any combination of a plurality of related recited items or any of a plurality of related recited items.

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.

Terms used in this application 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 application, the terms "include" or "have" are intended to designate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other features It should be understood that the presence or addition of numbers, 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 application, they should not be interpreted in an ideal or excessively formal meaning. don't

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in more detail. In order to facilitate overall understanding in the description of the present invention, the same reference numerals are used for the same components in the drawings, and redundant descriptions of the same components are omitted.

A communication system to which embodiments according to the present invention are applied will be described. A communication system to which embodiments according to the present invention are applied is not limited to the contents described below, and embodiments according to the present invention can be applied to various communication systems. Here, the communication system may be used in the same sense as a communication network.

1 is a conceptual diagram illustrating a first embodiment of a communication system.

Referring to FIG. 1, a communication system 100 includes a plurality of communication nodes 110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3, 130-4, 130-5, 130-6). A plurality of communication nodes are 4G communication (eg, long term evolution (LTE), advanced (LTE-A)), 5G communication (eg, new radio (NR)) specified in the 3rd generation partnership project (3GPP) standard ), etc. can be supported. 4G communication may be performed in a frequency band of 6 GHz or less, and 5G communication may be performed in a frequency band of 6 GHz or more as well as a frequency band of 6 GHz or less.

For example, for 4G communication and 5G communication, a plurality of communication nodes may use a code division multiple access (CDMA)-based communication protocol, a wideband CDMA (WCDMA)-based communication protocol, a time division multiple access (TDMA)-based communication protocol, FDMA (frequency division multiple access)-based communication protocol, OFDM (orthogonal frequency division multiplexing)-based communication protocol, Filtered OFDM-based communication protocol, CP (cyclic prefix)-OFDM-based communication protocol, DFT-s-OFDM (discrete Fourier transform-spread-OFDM) based communication protocol, OFDMA (orthogonal frequency division multiple access) based communication protocol, SC (single carrier)-FDMA based communication protocol, NOMA (Non-orthogonal multiple access), GFDM (generalized frequency) division multiplexing)-based communication protocol, FBMC (filter bank multi-carrier)-based communication protocol, UFMC (universal filtered multi-carrier)-based communication protocol, SDMA (Space Division Multiple Access)-based communication protocol, etc. can be supported. .

In addition, the communication system 100 may further include a core network. When the communication system 100 supports 4G communication, the core network may include a serving-gateway (S-GW), a packet data network (PDN)-gateway (P-GW), a mobility management entity (MME), and the like. there is. When the communication system 100 supports 5G communication, the core network may include a user plane function (UPF), a session management function (SMF), an access and mobility management function (AMF), and the like.

Meanwhile, a plurality of communication nodes 110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3, 130-1 constituting the communication system 100 4, 130-5, 130-6) may each have the following structure.

2 is a block diagram showing a first embodiment of a communication node constituting a communication system.

Referring to FIG. 2 , a communication node 200 may include at least one processor 210, a memory 220, and a transceiver 230 connected to a network to perform communication. In addition, the communication node 200 may further include an input interface device 240, an output interface device 250, a storage device 260, and the like. Each component included in the communication node 200 may be connected by a bus 270 to communicate with each other.

However, each component included in the communication node 200 may be connected through an individual interface or an individual bus centered on the processor 210 instead of the common bus 270 . For example, the processor 210 may be connected to at least one of the memory 220, the transmission/reception device 230, the input interface device 240, the output interface device 250, and the storage device 260 through a dedicated interface. .

The processor 210 may execute a program command stored in at least one of the memory 220 and the storage device 260 . The processor 210 may refer to a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which methods according to embodiments of the present invention are performed. Each of the memory 220 and the storage device 260 may include at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory 220 may include at least one of a read only memory (ROM) and a random access memory (RAM).

Referring back to FIG. 1, the communication system 100 includes a plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2), a plurality of terminals 130- 1, 130-2, 130-3, 130-4, 130-5, 130-6). Base stations 110-1, 110-2, 110-3, 120-1, and 120-2 and terminals 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 The inclusive communication system 100 may be referred to as an “access network”. Each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 may form a macro cell. Each of the fourth base station 120-1 and the fifth base station 120-2 may form a small cell. The fourth base station 120-1, the third terminal 130-3, and the fourth terminal 130-4 may belong to the cell coverage of the first base station 110-1. The second terminal 130-2, the fourth terminal 130-4, and the fifth terminal 130-5 may belong to the cell coverage of the second base station 110-2. The fifth base station 120-2, the fourth terminal 130-4, the fifth terminal 130-5, and the sixth terminal 130-6 may belong to the cell coverage of the third base station 110-3. there is. The first terminal 130-1 may belong to the cell coverage of the fourth base station 120-1. The sixth terminal 130-6 may belong to the cell coverage of the fifth base station 120-2.

Here, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 is a NodeB, an evolved NodeB, a base transceiver station (BTS), Radio base station, radio transceiver, access point, access node, RSU (road side unit), RRH (radio remote head), TP (transmission point), TRP ( transmission and reception ooint), eNB, gNB, etc.

Each of the plurality of terminals 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 is a UE (user equipment), terminal, access terminal, mobile Mobile terminal, station, subscriber station, mobile station, portable subscriber station, node, device, IoT (Internet of Thing) It may be referred to as a device, a mounted device (mounted module/device/terminal or on board device/terminal, etc.), and the like.

Among the communication nodes, even when a method performed in a first communication node (eg, transmission or reception of a signal) is described, a second communication node corresponding to the method performed in the first communication node and a method (eg, transmission or reception of a signal) corresponding thereto are described. For example, reception or transmission of a signal) may be performed. That is, when the operation of the terminal is described, the corresponding base station may perform an operation corresponding to the operation of the terminal. Conversely, when the operation of the base station is described, a terminal corresponding thereto may perform an operation corresponding to the operation of the base station. Next, the frame structure of the C-band communication system between the UAV and the ground or between UAVs will be described.

An UAV communication system in C band may be composed of a C-band ground radio station (C-GRS) and an UAV. Uplink transmission of remote command (TC, Telecommand) control data (hereinafter referred to as control data) from ground radio station to UAV, and mission performance data such as telemetry (TM) data and HD-level video from UAV to terrestrial radio station (hereinafter referred to as mission data) data) may be configured as a downlink that transmits.

Also, when a terrestrial radio station performs a function of a base station, transmission from a terrestrial radio station to a UAV may mean downlink transmission, and transmission from an UAV to a terrestrial radio station may mean uplink transmission.

The uplink transmission operation described in the embodiments below may be applied to a downlink transmission operation, and the downlink transmission operation described in the embodiments below may be applied to an uplink transmission operation.

Mission data is data related to mission performance and may generally have a broader bandwidth than control data. On the other hand, control data is data related to UAV flight control, status monitoring, system management, etc., and may have narrowband characteristics, but may require high reliability.

The UAV communication system is a physical layer of UAV communication that supports both UAV-to-ground and UAV-to-UAV direct communication while supporting both the requirements of UAV control data requiring high reliability and mission data requiring broadband. The design and communication method mainly targets the communication system for UAV missions operating in the C band (5091-5150 MHz), but can be applied to other systems as well.

The communication method for the UAV mission described above may satisfy one or more of the requirements shown in Table 1 below.

[Configuration of physical layer frame structure for simultaneous uplink/downlink transmission]

The UAV communication system can perform multiple access to a licensed band physical channel for a mission based on a single carrier-frequency domain equalization (SC-FDE) method having a Cyclic Prefix (CP). The UAV communication system may apply Time Division Duplex (TDD) as a duplex method.

The frame structure of the UAV communication system is PUPCH (Physical Uplink Payload Channel), which is an uplink physical channel for transmitting data for control of the licensed band communication physical layer for C band mission, and a downlink physical channel for simultaneously transmitting control and mission data. It can be configured as a physical downlink payload channel (PDPCH). PUPCH can support not only P2P (Point-to-Point) mode in which one terrestrial radio station communicates with one UAV, but also P2MP (Point-to-MultiPoint) mode in which communication is exchanged with up to 10 UAVs simultaneously. .

Embodiments described below may be applied to other communication systems (eg, NR) as well as LTE. In the following embodiments, the data channel may indicate at least one of a downlink data channel (eg, PDPCH) and an uplink data channel (eg, PUPCH). A payload channel may be used as a term referring to a channel that transmits and receives mission data.

3 is a conceptual diagram showing a first embodiment of a frame structure of an UAV communication system.

Referring to FIG. 3, the first layer (physical layer) of the UAV communication system is bandwidth agnostic based on a phase shift keying (PSK) symbol rate in order for the first layer to adaptively respond to various spectrum allocations. can be defined in an agnostic way.

The frame structure may consist of 5 subframes having a period of 50 ms and a period of 10 ms subframe. Each frame has a length of T _f =50 ms and may be composed of subframes 1 to 5 having a length of T _sf =10 ms. Whether to use a subframe may be determined by an instruction from an upper layer (eg, MAC layer) of each subframe. The UAV communication system may not transmit a corresponding subframe when each subframe is not used. A radio frame number corresponding to an integer multiple of every 20 may start at an integer multiple of 1 second in UTC time.

4 is a conceptual diagram illustrating a first embodiment of a subframe structure when a bandwidth is 20 MHz in an UAV communication system.

Referring to FIG. 4, each subframe has a length of T _sfi =10 ms (eg, i is 1 to 5) and may be composed of consecutive data segments. The data segment may consist of two SC-FDE preamble sections and N _{sf,slot slot} sections, and may have the same structure and length regardless of the subframe number.

Each subframe may include N _sf,slot slots, and a general supported configuration may have a value of any one of Tables 2 and 3 below. The UAV communication system can be applied similarly to 20 MHz at 10 MHz and 5 MHz. When the bandwidth is 5 MHz, 10 MHz or 20 MHz, T _s may have values shown in Table 2 below.

)는 표 3과 같은 값을 가질 수 있다.When the bandwidth is 5 MHz, 10 MHz or 20 MHz, the number of slots in a subframe (

) may have values shown in Table 3.

The UAV communication system uses each slot based on the subframe configuration in Tables 2 and 3 for any purpose, such as guard time for PUPCH, PDPCH, TDD, and/or air-to-air (A2A) support. Depending on usage, various subframe configurations may be possible.

5 is a conceptual diagram illustrating a first embodiment of a subframe structure for supporting TDD, A2A, and A2G (air-to-ground) communication in an UAV communication system.

Referring to FIG. 5, in the subframe structure for supporting TDD, A2G, and A2A communication scenarios through bi-directional communication with PUPCH and PDPCH, each subframe has a total of 11 slots, one for PUPCH transmission and eight for PDPCH. transmission, and the remaining two slots may be configured as slots for guard intervals. Each subframe may include one or more front symbols and one or more tail symbols, and interference between uplink and downlink transmissions and/or between downlink transmissions for the first drone and the second drone. may include a guard period to prevent

In an uplink slot for PUPCH transmission, two control media access control (MAC) protocol data units (PDUs) for the first and second UAVs may be multiplexed and transmitted. In the downlink slot for PDPCH transmission, one or more control MAC PDUs and one or more mission MAC PDUs for the first UAV may be multiplexed and transmitted. In addition, in the downlink slot for PDPCH transmission, one or more control MAC PDUs and one or more mission MAC PDUs for the second UAV may be multiplexed and transmitted.

Each slot may be composed of N _{slot,data_blocks} SC-FDE data blocks and N _{slot,pilot_blocks} SC-FDE pilot blocks. SC-FDE pilot blocks may be arranged considering multipath fading. The length of each slot can be calculated using Equation 1 below.

When the bandwidth is 5 MHz, 10 MHz, or 20 MHz, the number of SC-FDEs, SC-FDE pilots, and SC-FDE data blocks in a slot may have values shown in Table 4 below.

6 is a conceptual diagram illustrating a first embodiment of arrangement of SC-FDE pilots and SC-FDE data blocks in slots in an UAV communication system.

Referring to FIG. 6, within a slot, an SC-FDE pilot block may be inserted every block following 5 SC-FDE data blocks.

7 is a conceptual diagram illustrating a first embodiment of a configuration of an SC-FDE block within a slot in an UAV communication system.

Referring to FIG. 7, each block may be composed of N _CP CP samples (T _s length unit samples) and N _{block,samples} block samples, and M _{block,symbols} modulation symbols may be transmitted.

The length (T _Block ) of the SC-FDE block, which is divided into SC-FDE pilot and SC-FDE data blocks according to the shape, can be calculated using Equation 2 below.

Since SC-FDE pilot and SC-FDE data blocks have the same structure, T _Block =T _{data_Block} =T _{pilot_Block} , N _{block,samples} =N _{data_block,samples} =N _{pilot_block,samples} and M _{block,symbols} =M _{data_block,symbols} = It has the value of M _{pilot_block,symbols} . where T _{data_Block} , T _{pilot_Block} , N _{data_block,samples} , N _{pilot_block,samples} , M _{data_block,symbols} and M _{pilot_block,symbols} are the SC-FDE data block length, SC-FDE pilot block length, SC-FDE data block sample number, The number of SC-FDE pilot block samples, the number of SC-FDE data block modulation symbols, and the number of SC-FDE pilot block modulation symbols may be indicated. Depending on the bandwidth, SC-FDE pilot and SC-FDE data block settings may have values shown in Table 5 below.

The SC-FDE pilot block may consist of N _CP,samples CP samples and N _{pilot_block,samples} pilot samples, and may carry M _{pilot_block,symbols} pilot symbol sequences. The length of the SC-FDE pilot block (T _{pilot_Block} ) can be obtained using Equation 3 below.

The SC-FDE data block may consist of N _CP,samples CP samples and N _{data_block,samples} data samples, and may carry M _{data_block,symbols} data symbol sequences. The length of the SC-FDE data block (T _{data_Block} ) can be obtained using Equation 4 below.

The first SC-FDE preamble block may include N _CP,samples CP samples and N _{1st_preamble_block,samples} preamble block samples, and may transmit M _{1st_preamble_block,symbols} symbol sequences. The length (T _{1st_preamble_block} ) of the first SC-FDE preamble block can be obtained using Equation 5 below.

The second SC-FDE preamble block may include N _CP,samples CP samples and N _{2nd_preamble_block,samples} preamble block samples, and may transmit M _{2nd_preamble_block,symbols} symbol sequences. The length of the second SC-FDE preamble block (T _{2nd_preamble_block} ) can be obtained using Equation 6 below.

Depending on the bandwidth, the first and second SC-FDE preamble block settings may have values shown in Tables 6 and 7 below.

A front guard symbol may consist of N _{FrontGuard,samples samples} without CP samples, and may transmit M _{FrontGuard,symbols} symbol sequences. The length of the front guard symbol included in the guard period (T _FrontGuard ) can be obtained using Equation 7 below.

Depending on the bandwidth, the front guard setting may have values shown in Table 8 below.

A tail guard symbol may consist of N _{TailGuard,samples samples} without CP samples, and may transmit M _{TailGuard,symbols} symbol sequences. The length (T _TailGuard ) of the tail guard symbol included in the guard period can be obtained using Equation 8 below.

Depending on the bandwidth, tail guard settings may have values shown in Table 9 below.

[Data unit multiplexing method]

8 is a flowchart illustrating a first embodiment of a procedure for transmitting and receiving data between a UAV and a terrestrial radio station within one subframe in an UAV communication system.

Referring to FIG. 8, each subframe can support two UAVs, and for this purpose, the terrestrial radio station can multiplex two MAC PDUs for control into an uplink slot (S601). The terrestrial radio station may transmit a control MAC PDU for the first UAV to the first UAV through an uplink slot among multiplexed control MAC PDUs. In addition, the terrestrial radio station may transmit a control MAC PDU for the second UAV to the second UAV through an uplink slot among the multiplexed control MAC PDUs (S602). The first UAV may receive a control MAC PDU for the first UAV among two MAC PDUs for control multiplexed in an uplink slot from a terrestrial radio station. In addition, the second UAV may receive a control MAC PDU for the second UAV among two MAC PDUs for control multiplexed in an uplink slot from a terrestrial radio station.

The terrestrial radio station may allocate downlink slot A to the first UAV in order to receive the PDPCH from the first UAV. In addition, the terrestrial radio station may allocate downlink slot B to the second UAV in order to receive the PDPCH from the second UAV (S603). Here, downlink slot A may mean four independent downlink slots for receiving a PDPCH from a first UAV, and downlink slot B mean four independent downlink slots for receiving a PDPCH from a second UAV. can do.

Accordingly, the first UAV can transmit the PDPCH for the first UAV to the terrestrial radio station using downlink slot A. The terrestrial radio station may receive the PDPCH from the first UAV using downlink slot A. In addition, the second UAV may transmit a PDPCH for the second UAV to the terrestrial radio station using downlink slot B. The terrestrial radio station may receive the PDPCH from the second UAV using downlink slot B. One UAV may use all downlink slots.

More specifically, the first UAV may multiplex MAC PDUs for control and mission of the first UAV in downlink slot A (S604). Here, the first UAV may generate a MAC PDU for control to be transmitted to the terrestrial radio station based on the MAC PDU for control received from the terrestrial radio station. The first UAV may transmit the multiplexed MAC PDUs for control and mission to the terrestrial radio station through downlink slot A (S605). The terrestrial radio station may receive control and mission MAC PDUs from the first UAV through downlink slot A.

The second UAV may multiplex MAC PDUs for control and mission of the second UAV in downlink slot B (S606). Here, the second UAV may generate a MAC PDU for control to be transmitted to the terrestrial radio station based on the MAC PDU for control received from the terrestrial radio station. The second UAV may transmit the multiplexed MAC PDUs for control and mission to the terrestrial radio station through downlink slot B (S607). The terrestrial radio station may receive control and mission MAC PDUs from the second UAV through downlink slot B.

How the UAV communication system can multiplex the PUPCH in the physical layer and which PDPCH is allocated to which slot can be determined by a higher layer (eg, MAC layer). Also, how the UAV communication system multiplexes the MAC PDU for control and the MAC PDU for mission on the PDPCH can be determined by a higher layer (eg, MAC layer).

MAC PDUs for control within the PUPCH may be multiplexed based on the multiplexing scheme of Table 10 below. One or more control MAC PDUs and one or more mission MAC PDUs in the PDPCH may be multiplexed based on the multiplexing method of Table 11 below.

[Encoding method]

As an encoding scheme, turbo encoding based on rate matching may be applied. A low coding rate can be applied to control data for high link reliability, and various modulation and coding modes having various transmission rates can be applied to mission data in consideration of various mission data. The Modulation and Coding Scheme (MCS) and transport block size of PUPCH may have any one of the configurations of Table 12, and the MCS and transport block size of PDPCH may have one of the configurations of Table 13. there is.

[Physical layer parameters]

Physical layer parameters used in the communication method performed in the UAV communication system may have values shown in Table 14 below.

The methods according to the present invention may be implemented in the form of program instructions that can be executed by various computer means and recorded on a computer readable medium. Computer readable media may include program instructions, data files, data structures, etc. alone or in combination. Program instructions recorded on a computer readable medium may be specially designed and configured for the present invention or may be known and usable to those skilled in computer software.

Examples of computer readable media include hardware devices specially configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include high-level language codes that can be executed by a setting computer using an interpreter or the like as well as machine language codes such as those produced by a compiler. The hardware device described above may be configured to operate with at least one software module to perform the operations of the present invention, and vice versa.

Although described with reference to the above embodiments, those skilled in the art will understand that the present invention can be variously modified and changed without departing from the spirit and scope of the present invention described in the claims below. You will be able to.

Claims (15)

As a communication method performed by a terrestrial radio station,
Transmitting an uplink channel including a medium access control (MAC) protocol data unit (PDU) in an uplink slot;
allocating one or more downlink slots to one or more UAVs receiving the uplink channel; and
And receiving a downlink channel including information generated based on information included in the uplink channel through the one or more downlink slots. The method of claim 1,
Transmitting an uplink channel including the MAC PDU in an uplink slot,
Multiplexing a first MAC PDU and a second MAC PDU when a plurality of UAVs including a first UAV and a second UAV communicate with the terrestrial radio station,
The first MAC PDU and the second MAC PDU belong to the MAC PDU, the first MAC PDU includes control information for a first UAV, and the second MAC PDU includes control information for a second UAV Including, how to communicate. The method of claim 1,
The step of allocating the one or more downlink slots,
Allocating a downlink slot A for the first UAV when a plurality of UAVs including a first UAV communicate with the terrestrial radio station;
The downlink slot A belongs to the one or more downlink slots and is used to receive the downlink channel from the first UAV. The method of claim 3,
Allocating a downlink slot B for a second UAV among the plurality of UAVs;
The downlink slot B belongs to the one or more downlink slots and is used to receive the downlink channel from the second UAV. The method of claim 1,
Information indicating whether a subframe composed of the uplink slot and the one or more downlink slots is transmitted is received through higher layer signaling. The method of claim 5,
The subframe includes one or more guard intervals,
Wherein the guard interval is set to prevent "interference between uplink transmission and downlink transmission" or "interference between downlink transmissions". The method of claim 5,
The subframe includes one or more single carrier-frequency domain equalization (SC-FDE) preamble blocks, and the uplink slot and the one or more downlink slots each include one or more SC-FDE pilot blocks. and one or more SC-FDE data blocks, wherein the SC-FDE pilot blocks are arranged in consideration of multipath fading. As a communication method performed by the first UAV,
Receiving an uplink channel through an uplink slot;
generating one MAC PDU by multiplexing the first MAC PDU and the second MAC PDU; and
Transmitting a downlink channel including the multiplexed MAC PDU in one or more downlink slots;
The first MAC PDU is generated based on information included in the uplink channel, and the type of information included in the first MAC PDU is different from the type of information included in the second MAC PDU. The method of claim 8,
The communication method of claim 1 , wherein the first MAC PDU includes control information, and the second MAC PDU includes task information. The method of claim 8,
Transmitting the downlink channel in one or more downlink slots,
Transmitting the downlink channel through a downlink slot A when a plurality of UAVs including the first UAV and the second UAV communicate with the terrestrial radio station;
The downlink slot B other than the downlink slot A is used for transmission in the second UAV. As a terrestrial radio station in a communication system,
processor;
a memory that communicates electronically with the processor; and
Includes instructions stored in the memory;
When the instructions are executed by the processor, the instructions cause the terrestrial radio station to:
transmits an uplink channel including MAC PDUs in an uplink slot;
allocating one or more downlink slots to one or more UAVs receiving the uplink channel; and
and cause receiving, via the one or more downlink slots, a downlink channel including information generated based on information included in the uplink channel. The method of claim 11,
When the uplink channel including the MAC PDU is transmitted in an uplink slot, the commands are the terrestrial radio station,
Operate to cause multiplexing of a first MAC PDU and a second MAC PDU when a plurality of UAVs including a first UAV and a second UAV communicate with the terrestrial radio station;
The first MAC PDU and the second MAC PDU belong to the MAC PDU, the first MAC PDU includes control information for a first UAV, and the second MAC PDU includes control information for a second UAV Including, terrestrial radio stations. The method of claim 11,
In the case of allocating the one or more downlink slots, the commands may cause the terrestrial radio station to:
Operate to cause allocation of a downlink slot A for the first UAV when a plurality of UAVs, including a first UAV, communicate with the terrestrial radio station;
The downlink slot A belongs to the one or more downlink slots and is used to receive the downlink channel from the first UAV. The method of claim 13,
Operate to cause allocation of a downlink slot B for a second UAV of the plurality of UAVs;
The downlink slot B belongs to the one or more downlink slots and is used to receive the downlink channel from the second UAV. The method of claim 11,
The terrestrial radio station that operates to cause information indicating whether or not transmission of a subframe composed of the uplink slot and the one or more downlink slots is received through higher layer signaling.

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