KR20210003042A - Method and apparatus for reducing power consumption in non-terrestrial network - Google Patents

Abstract

Disclosed are a method for reducing power consumption on a non-terrestrial network and an apparatus thereof. A terminal operating method includes the following steps of: starting a first timer indicating a first time section required for a retransmission operation of downlink data if a transmission operation of the downlink data is started for on-duration in accordance with a DRX cycle; starting a second timer at a termination moment of the first timer; performing a downlink monitoring operation in a second time section in accordance with the second timer; and receiving the downlink data in a downlink resource indicated by control information from a non-terrestrial node if the control information for the retransmission operation is received from the non-terrestrial node in the second time section. Accordingly, performance of a communication system can be improved.

Description

Method and apparatus for reducing power consumption in a non-terrestrial network {METHOD AND APPARATUS FOR REDUCING POWER CONSUMPTION IN NON-TERRESTRIAL NETWORK}

The present invention relates to a communication technology in a non-terrestrial network, and more particularly, to a technology for reducing power consumption in a terminal.

In order to process rapidly increasing radio data, a frequency band higher than the frequency band of LTE (long term evolution) (or LTE-A) (eg, a frequency band of 6 GHz or less) (eg, a frequency band of 6 GHz or higher) A communication network using (for example, a new radio (NR) communication network) is being considered. The NR communication network can support not only a frequency band of 6 GHz or lower but also a frequency band of 6 GHz or higher, and can support various communication services and scenarios compared to an LTE communication network. For example, the usage scenario of the NR communication network may include enhanced Mobile BroadBand (eMBB), Ultra Reliable Low Latency Communication (URLLC), and Massive Machine Type Communication (mMTC).

The NR communication network may provide communication services to terminals located on the terrestrial. Recently, the demand for communication services for non-terrestrial planes, drones, unmanned aerial vehicles (UAVs), UBS (UAN base stations), satellites, etc. is increasing. For this purpose, technologies for a non-terrestrial network (NTN) are being discussed. Non-terrestrial networks can be implemented based on NR technology. For example, in a non-terrestrial network, communication between a satellite and a communication node (e.g., user equipment (UE)) located on the ground or a communication node (e.g., airplane, UAV, drone) located on the ground is NR It can be done based on technology. In a non-terrestrial network, a satellite may perform the function of a base station in an NR communication network. Here, the non-terrestrial network may mean a long-distance communication network in terms of a communication range.

Meanwhile, in a non-terrestrial network, the terminal may perform communication using a 6GHz~90GHz band. That is, high-speed data transmission can be performed using a wide bandwidth in a non-terrestrial network. In a non-terrestrial network, since a round trip delay (RTD) between a satellite and a terminal is long, a transmission/reception method and a control method according to a radio protocol taking this into account are required. In particular, there is a need for methods for reducing power consumption of a terminal in a non-terrestrial network.

An object of the present invention for solving the above problems is to provide a method and apparatus for reducing power consumption in consideration of a transmission delay in a non-terrestrial network.

In order to achieve the above object, the operation method of the terminal according to the first embodiment of the present invention is, when the transmission operation of downlink data starts in the on-duration according to the DRX cycle, the first required for the retransmission operation of the downlink data Starting a first timer indicating one time interval, starting a second timer at an end point of the first timer, performing a downlink monitoring operation in a second time interval according to the second timer, And when control information for the retransmission operation is received from a non-ground node in the second time interval, receiving the downlink data from the non-ground node in a downlink resource indicated by the control information. And the first timer is set in consideration of a transmission delay between the non-ground node and the terminal.

Here, the first timer may be set in units of HARQ processes in the non-terrestrial network.

Here, the first time interval may be a minimum time interval required to allocate the downlink resource for the retransmission operation in the non-terrestrial network.

Here, the length of the first time interval may be set as a multiple of the DRX cycle.

Here, the end point of the first time period may be set to a start point of the on-duration, an end point of the on-duration, or an arbitrary point in the on-duration.

Here, the first time interval may be a sum of the minimum time interval required to allocate the downlink resource for the retransmission operation in the terrestrial network and the transmission delay.

Here, when the transmission operation is successfully completed, the first timer may be stopped, and when the transmission operation fails, the first timer may continue to operate.

Here, when the control information for the retransmission operation is received from the non-ground node, the second timer may be stopped.

Here, the method of operating the terminal may further include receiving a message including information on the first timer and information on the second timer from the non-ground node.

The terminal according to the first embodiment of the present invention for achieving the above object includes a processor, a memory in electronic communication with the processor, and instructions stored in the memory, and when the instructions are executed by the processor, The commands start a first timer indicating a first time interval required for the retransmission operation of the uplink data when the terminal starts the transmission operation of uplink data in the on-duration according to the DRX cycle, and the first 1 operates to cause a second timer to start at the end of the timer, and to cause retransmission of the uplink data to a non-ground node by using uplink resources within a second time interval according to the second timer, and the The first timer is set in consideration of a transmission delay between the non-ground node and the terminal.

Here, the first timer may be set in units of HARQ processes in the non-terrestrial network.

Here, the first time interval may be a minimum time interval necessary for allocating the uplink resource for the retransmission operation in the non-terrestrial network, and the length of the first time interval is set as a multiple of the DRX cycle. I can.

Here, the end point of the first time period may be set to a start point of the on-duration, an end point of the on-duration, or an arbitrary point in the on-duration.

Here, the first time period may be a sum of the minimum time period required to allocate the uplink resource for the retransmission operation in the terrestrial network and the transmission delay.

Here, the uplink resource may be a radio resource or a CG resource indicated by a DCI received from the non-ground node in the second time period.

Here, the instructions may be further executed to cause receiving from the non-ground node a message including information of the first timer and information of the second timer.

In order to achieve the above object, a method of operating a non-ground node according to a third embodiment of the present invention includes information of a first timer indicating a first time interval required for a retransmission operation of downlink data and a downlink monitoring operation. Transmitting a message including information of a second timer indicating the second time interval to be performed to the terminal, performing a transmission operation of the downlink data in an on-duration according to the DRX period, and the transmission operation In case of failure, transmitting control information for the retransmission operation to the terminal in the second time interval after the first time interval, wherein the first time interval starts from a time point when the transmission operation is performed, The second time interval starts from the end of the first time interval, and the first timer is set in consideration of a transmission delay between the non-ground node and the terminal.

Here, the first time interval may be a minimum time interval necessary for allocating the downlink resource for the retransmission operation in the non-terrestrial network, and the length of the first time interval is set as a multiple of the DRX cycle. I can.

Here, the end point of the first time period may be set to a start point of the on-duration, an end point of the on-duration, or an arbitrary point in the on-duration.

Here, the first time interval may be a sum of the minimum time interval required to allocate the downlink resource for the retransmission operation in the terrestrial network and the transmission delay.

According to the present invention, a communication node (eg, a non-terrestrial node, a terminal) in a non-terrestrial network can perform a discontinuous reception (DRX) operation. In this case, parameters (eg, timers) for a (re)transmission operation of data may be set in consideration of a DRX cycle and/or a transmission delay in a non-terrestrial network. Therefore, in a non-terrestrial network supporting the DRX operation, the (re)transmission operation of data can be efficiently performed, and power consumption in the terminal can be reduced.

1 is a conceptual diagram showing a first embodiment of a communication network.
2 is a block diagram showing the first embodiment of a communication node constituting a communication network.
3 is a conceptual diagram illustrating a first embodiment of an operating state of a terminal in a communication network.
4 is a conceptual diagram showing a first embodiment of a non-terrestrial network.
5 is a conceptual diagram showing a second embodiment of a non-terrestrial network.
6 is a conceptual diagram showing a third embodiment of a non-terrestrial network.
7 is a timing diagram illustrating a first embodiment of a DRX operation in a terminal operating in an RRC connected state.
8 is a timing diagram showing a first embodiment of a DRX operation in a non-terrestrial network.

In the present invention, various modifications may be made and various embodiments may be provided, and specific embodiments will be illustrated in the drawings and described in detail. However, this is not intended to limit the present invention to a specific embodiment, it is to be understood to include all changes, equivalents, or 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 used only for the purpose of distinguishing one component from another component. For example, without departing from the scope of the present invention, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. The term and/or includes a combination of a plurality of related listed items or any of a plurality of related listed items.

When a component is referred to as being "connected" or "connected" to another component, it is understood that it may be directly connected or connected to the other component, but other components may exist in the middle. Should be. On the other hand, when a component is referred to as being "directly connected" or "directly connected" to another component, it should be understood that there is no other component in the middle.

The terms used in the present 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 indicates otherwise. In the present application, terms such as "comprise" or "have" are intended to designate the presence of features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, but one or more other features. It is to be understood that the presence or addition of elements or numbers, steps, actions, components, parts, or combinations thereof, does not preclude in advance.

Unless otherwise defined, 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 as defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and should not be interpreted as an ideal or excessively formal meaning unless explicitly defined in the present application. Does not.

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

A communication network to which embodiments according to the present invention are applied will be described. The communication network is a non-terrestrial network (NTN), a 4G communication network (eg, a long-term evolution (LTE) communication network), a 5G communication network (eg, a new radio (NR) communication network). ), etc. The 4G communication network and the 5G communication network may be classified as a terrestrial network.

The non-terrestrial network may operate based on LTE technology and/or NR technology. The non-terrestrial network can support communication in a frequency band of 6 GHz or higher as well as a frequency band of 6 GHz or less. The 4G communication network can support communication in a frequency band of 6 GHz or less. The 5G communication network can support communication in not only a frequency band below 6GHz but also a frequency band above 6GHz. The communication network to which the embodiments according to the present invention are applied is not limited to the contents described below, and the embodiments according to the present invention can be applied to various communication networks. Here, the communication network may have the same meaning as the communication system.

1 is a conceptual diagram showing a first embodiment of a communication network.

Referring to FIG. 1, the communication network 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 (e.g., long term evolution (LTE), LTE-A (advanced)), 5G communication (e.g., new radio) specified in the 3rd generation partnership project (3GPP) standard. ), etc. 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 include 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, Frequency division multiple access (FDMA)-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 can be supported. .

In addition, the communication network 100 may further include a core network. When the communication network 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. have. When the communication network 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- constituting the communication network 100 4, 130-5, 130-6) Each may have the following structure.

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

Referring to FIG. 2, the communication node 200 may include at least one processor 210, a memory 220, and a transmission/reception device 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, and a storage device 260. Each of the components included in the communication node 200 may be connected by a bus 270 to perform communication with each other.

However, each of the components included in the communication node 200 may be connected through an individual interface or an individual bus centering 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 mean 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 be configured with at least one of a volatile storage medium and a nonvolatile storage medium. For example, the memory 220 may be formed of at least one of a read only memory (ROM) and a random access memory (RAM).

Referring back to FIG. 1, the communication network 100 includes a plurality of base stations 110-1, 110-2, 110-3, 120-1, 120-2, and 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, 120-2) and terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) The containing communication network 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 within the cell coverage of the third base station 110-3. have. 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 point), eNB, gNB, and the like.

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

Meanwhile, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may operate in different frequency bands or may operate in the same frequency band. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be connected to each other through an ideal backhaul link or a non-ideal backhaul link, , Information can be exchanged with each other through an ideal backhaul link or a non-ideal backhaul link. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be connected to the core network through an ideal backhaul link or a non-ideal backhaul link. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 transmits a signal received from the core network to the corresponding terminal 130-1, 130-2, 130-3, 130 -4, 130-5, 130-6), and the signal received from the corresponding terminal (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) Can be transferred to.

In addition, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 transmits MIMO (e.g., single user (SU)-MIMO, multi-user (MU)- MIMO, massive MIMO, etc.), coordinated multipoint (CoMP) transmission, carrier aggregation (CA) transmission, transmission in an unlicensed band, direct communication between terminals (device to device communication, D2D) (or, ProSe ( proximity services)). Here, each of the plurality of terminals 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 is a base station 110-1, 110-2, 110-3, 120-1 , 120-2) and operations supported by the base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be performed. For example, the second base station 110-2 may transmit a signal to the fourth terminal 130-4 based on the SU-MIMO scheme, and the fourth terminal 130-4 may transmit a signal to the fourth terminal 130-4 by the SU-MIMO scheme. A signal may be received from the second base station 110-2. Alternatively, the second base station 110-2 may transmit a signal to the fourth terminal 130-4 and the fifth terminal 130-5 based on the MU-MIMO method, and the fourth terminal 130-4 And each of the fifth terminal 130-5 may receive a signal from the second base station 110-2 by the MU-MIMO method.

Each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 may transmit a signal to the fourth terminal 130-4 based on the CoMP scheme, and The terminal 130-4 may receive signals from the first base station 110-1, the second base station 110-2, and the third base station 110-3 by the CoMP method. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 has terminals 130-1, 130-2, 130-3, and 130-4 belonging to their cell coverage. , 130-5, 130-6) and the CA method can transmit and receive signals. Each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 can control D2D between the fourth terminal 130-4 and the fifth terminal 130-5. And, each of the fourth terminal 130-4 and the fifth terminal 130-5 may perform D2D under the control of the second base station 110-2 and the third base station 110-3, respectively. .

Next, a transmission/reception method and a control method in a communication network will be described. Even when a method performed in the first communication node (for example, transmission or reception of a signal) among communication nodes is described, the second communication node corresponding thereto is a method corresponding to the method performed in the first communication node (e.g. For example, signal reception or transmission) 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, the terminal corresponding thereto may perform an operation corresponding to the operation of the base station.

In the embodiments below, UPF (or S-GW) may refer to a terminal communication node of the core network that exchanges packets (eg, control information, data) with a base station, and AMF (or MME) is It may refer to a communication node of a core network that performs a control function in the wireless access section (or interface) of the terminal. Here, each of the S-GW, MME, AMF, and UPF may be referred to as different terms according to a function of a communication protocol (eg, a function of a core network) according to a radio access technology (RAT).

In a communication network supporting a dual connectivity function, a connection may be established between a terminal and a plurality of base stations. A plurality of base stations may provide services to the terminal. A plurality of base stations (eg, a plurality of base stations connected to a terminal) supporting the dual connectivity function may be classified into a master base station and a secondary base station. In the following embodiments, dual connectivity is a single-radio dual connectivity (SR-DC) by a plurality of base stations supporting the same RAT or a multi-radio (MR) by a plurality of base stations supporting different RATs. Can mean DC.

The master base station may be referred to as a “master node”. The master node may be a node that proactively performs an RRC function to support a dual connection function. The master node can provide a function of connecting the control plane with the core network. The master node may be composed of a plurality of cells. A plurality of cells included in the master node may be referred to as a master cell group (MCG). The MCG bearer may mean a bearer according to a logical channel configuration between the RLC layer and the MAC layer of a cell belonging to the MCG.

The secondary base station may be referred to as a “secondary node”. The secondary node may not provide a function of connecting the control plane to the core network. The secondary node may provide a service to the terminal by using additional radio resources. The secondary node may be composed of a plurality of cells. A plurality of cells included in the secondary node may be referred to as a secondary cell group (SCG). The split bearer may use a logical channel configuration between an RLC layer and a MAC layer of a cell belonging to an MCG and a logical channel configuration between an RLC layer and a MAC layer of a cell belonging to the SCG. The split bearer may be classified into a secondary node (SN) terminated bearer and a master node (MN) terminated bearer according to the type of a node performing the PDCP function. When the PDCP function for the split bearer is performed in the master node, the corresponding split bearer may be an MN end bearer. When the PDCP function for the split bearer is performed in the secondary node, the corresponding split bearer may be an SN termination bearer.

3 is a conceptual diagram illustrating a first embodiment of an operating state of a terminal in a communication network.

Referring to FIG. 3, the operating state of the terminal may be classified into an RRC connected state, an RRC inactive state, and an RRC idle state. When the terminal operates in the RRC connected state or in the RRC inactive state, the radio access network (RAN) (eg, a control function block of the RAN) and the base station are RRC connection configuration information and/or context information of the corresponding terminal (For example, RRC context information, AS (access stratum) context information) can be stored/managed. In addition, a terminal operating in an RRC connected state or an RRC inactive state may store RRC connection configuration information and/or context information.

"When the operating state of the terminal transitions from the RRC connected state to the RRC idle state" or ""When the operating state of the terminal transitions from the RRC inactive state to the RRC idle state", context information can be deleted from the RAN and the base station. The context information (eg, RRC context information) may include an identifier assigned to the terminal, PDU session information, encryption key (security key), capability information, and the like.

The UE operating in the RRC idle state monitors the downlink signal at the on-duration or active time according to the DRX (discontinuous reception) period set for the low power consumption operation (e.g., measurement Operation), it is possible to perform a cell selection operation or a cell reselection operation for camping to an optimum base station (eg, an optimum cell). In order to camp on a new base station (eg, a new cell), the terminal can obtain system information from the base station. In addition, when system information required by the terminal exists, the terminal may request transmission of system information. The terminal may perform an operation of receiving a paging message in on-duration or active time according to a paging occasion.

The terminal operating in the RRC connected state can set up a base station (eg, serving cell) and a radio bearer (eg, data radio bearer (DRB), signaling radio bearer (SRB)), and is required in the RRC connected state. Context information (eg, RRC context information) can be stored/managed. A terminal operating in an RRC connected state may perform a physical downlink control channel (PDCCH) monitoring operation using context information and connection configuration information. The terminal may receive downlink data from the base station through radio resources indicated by downlink control information (DCI) obtained by the PDCCH monitoring operation. In addition, the terminal may transmit uplink data to the base station using radio resources indicated by the DCI obtained by the PDCCH monitoring operation.

The mobility function for the terminal operating in the RRC connected state may be supported through a handover procedure when the base station is changed. For the handover procedure, the terminal may perform a measurement operation for a base station and/or an adjacent base station (eg, an adjacent cell) based on measurement and/or reporting parameters set by the base station, and the measurement result You can report to. In the following embodiments, the measurement operation may include an operation of reporting a measurement result. In addition, the terminal operating in the RRC connected state may perform a DRX operation based on DRX parameters set by the base station. For example, a terminal operating in an RRC connected state may perform a PDCCH monitoring operation in on-duration or active time according to the DRX cycle.

A terminal operating in the RRC inactive state may store/manage context information required for the RRC inactive state. A terminal operating in an RRC inactive state or an RRC idle state may perform a DRX operation based on DRX parameters set by the last base station (eg, serving cell). For example, a UE operating in an RRC inactive state may perform a monitoring operation or measurement operation of a downlink signal at an on-duration or active time according to the DRX cycle, and an optimal base station (e.g., an optimal cell ), a cell selection operation or a cell reselection operation may be performed based on a result of a monitoring operation or a measurement operation. The terminal may acquire system information to camp on a new base station (eg, a new cell) and, if necessary, may request transmission of system information (eg, system information required by the terminal). A terminal operating in an RRC inactive state or an RRC idle state may perform an operation of receiving a paging message in an on-duration or active time according to a paging occasion.

The communication procedure between the base station and the terminal may be performed based on a beamforming method. A signal transmitted from the terminal may be used to provide a mobility function between base stations or to select an optimal beam within the base station. A connection between the terminal and one or more base stations (eg, one or more cells) may be established, and one or more base stations may provide a service to the terminal. Connection establishment between the terminal and one or more base stations may be maintained. For example, one or more base stations may store/manage context information (eg, AS context information). Alternatively, the terminal may be located in the service area of the base station without establishing a connection with the base station.

When the beamforming method is used in the high frequency band, in the communication system, "beam level mobility function to change the set beam of the terminal", "mobility function to change the set beam between base stations (eg, cells)", "wireless A resource management function for changing the setting of a link" and the like may be supported.

In order to perform the mobility support function and the radio resource management function, the base station may transmit a synchronization signal (eg, a synchronization signal/physical broadcast channel (SS/PBCH) block) and/or a reference signal. In order to support multiple numerology, a frame format supporting symbols having different lengths may be set. In this case, the UE may perform a monitoring operation of a synchronization signal and/or a reference signal in a frame according to an initial neurology, a default neurology, or a default symbol length. Each of the initial neurology and default neurology is a frame format applied to a radio resource in which a UE-common search space is set, and a radio resource in which CORESET (control resource set) #0 of an NR communication system is set. The applied frame format and/or a synchronization symbol burst capable of identifying a cell in an NR communication system may be applied to a frame format applied to a radio resource to be transmitted.

The frame format is information of setting parameters for a subcarrier spacing, a control channel (e.g., CORESET), a symbol, a slot, and/or a reference signal in a radio frame (or subframe) (e.g. For example, it may mean a value of a setting parameter, an offset, an index, an identifier, a range, a period, an interval, and a duration. The base station may inform the terminal of the frame format using system information and/or a control message (eg, a dedicated control message).

The terminal connected to the base station may transmit a reference signal (eg, an uplink-only reference signal) to the corresponding base station using resources set by the corresponding base station. For example, the uplink-oriented reference signal may include a sounding reference signal (SRS). In addition, a terminal connected to a base station may receive a reference signal (eg, a downlink-oriented reference signal) from resources set by the base station from the base station. The downlink-oriented reference signal may be a channel state information-reference signal (CSI-RS), a phase tracking-reference signal (PT-RS), a demodulation-reference signal (DM-RS), or the like. Each of the base station and the terminal may perform a beam management operation by monitoring a configured beam or an active beam based on a reference signal.

For example, the base station may transmit a synchronization signal and/or a reference signal so that a terminal located in a communication service area can search for itself and perform a downlink synchronization maintenance operation, a beam setting operation, or a link monitoring operation. A terminal connected to a base station (eg, a serving base station) may receive radio resource configuration information of a physical layer for connection establishment and radio resource management from the base station. The radio resource configuration information of the physical layer may be configuration parameters included in the RRC control message in the LTE communication system and/or the NR communication system. For example, radio resource configuration information is PhysicalConfigDedicated, PhysicalCellGroupConfig , PDCCH - Config (Common), PDSCH-Config (Common), PDCCH - ConfigSIB1 , ConfigCommon , PUCCH - Config (Common), PUSCH-Config (Common), BWP - DownlinkCommon , BWP - UplinkCommon , ControlResourceSet, RACH - ConfigCommon , RACH - ConfigDedicated , RadioResourceConfigCommon , RadioResourceConfigDedicated , ServingCellConfig , ServingCellConfigCommon , and the like.

The radio resource setting information includes a setting period (or, an allocation period) of a signal (or radio resource) according to the frame format of the base station (or transmission frequency), time resource allocation information for transmission, frequency resource allocation information for transmission, It may include parameter values such as transmission timing (or allocation timing). To support multiple neurology, a frame format of a base station (or transmission frequency) may mean a frame format having different symbol lengths according to a plurality of subcarrier intervals within one radio frame. For example, in one radio frame (eg, a frame having a length of 10 ms), the number of symbols constituting each of a mini-slot, a slot, and a subframe may be different.

● Setting information of the transmission frequency and frame format of the base station

■ Transmission frequency configuration information: all the transmission carriers of the base station (eg, transmission frequency per cell), bandwidth part (BWP), transmission reference time or time difference information between the transmission frequencies of the base station (For example, a transmission period or offset parameter indicating the transmission reference time (or time difference) of the synchronization signal), etc.

■ Frame format setting information: Setting parameters of mini-slots, slots, and subframes having different symbol lengths according to subcarrier interval

● Setting information of a downlink reference signal (eg, CSI-RS, common RS, etc.)

■ The common RS configuration information is configuration parameters such as transmission period, transmission location, code sequence, masking sequence (or scrambling sequence) of a reference signal commonly applied in the coverage of the base station (or beam).

● Uplink control signal configuration information

■ SRS, reference signal for uplink beam sweeping (or beam monitoring), radio resource (or preamble) for uplink grant-free, etc.

● Downlink control channel (eg, PDCCH (physical downlink control channel)) configuration information

■ A reference signal for PDCCH demodulation, a beam common reference signal (eg, a reference signal that can be received by all terminals within the beam coverage), a reference signal for beam sweeping (or beam monitoring), a reference signal for channel estimation, etc.

● Uplink control channel (eg, PUCCH (physical uplink control channel)) configuration information

● Setting information of scheduling request signal

● Feedback (for example, ACK (acknowledgement) or NACK (negative ACK)) transmission resource configuration information in the HARQ (hybrid automatic repeat request) procedure

● The number of antenna ports, information on the antenna array, beam configuration and/or beam index mapping information for applying beamforming

● Setting information of a downlink signal and/or an uplink signal (or uplink access channel resource) for beam sweeping (or beam monitoring)

● Receive a beam that triggers a beam setup operation, a beam recovery operation, a beam reconfiguration operation, a radio link re-establishment operation, a beam change operation at the same base station, and a handover procedure to another base station. Setting information such as signals and control timers for the above-described operations

In a radio frame format supporting different symbol lengths to support multiple neurology, a setting period (or allocation period) of parameters constituting the above-described information, time resource allocation information, frequency resource allocation information, transmission timing, and /Or the allocation timing may be information set according to the corresponding symbol length (or subcarrier interval).

In the following embodiments, "Resource-Config information" may be a control message including one or more parameters among radio resource configuration information of a physical layer. In addition, "Resource-Config information" may mean a property and/or a setting value (or range) of an information element (or parameter) delivered by a control message. The information element (or parameter) delivered by the control message is radio resource configuration information that is commonly applied to the entire coverage of the base station (or beam) or dedicated to a specific terminal (or specific terminal group). It may be radio resource configuration information allocated to.

The configuration information included in the "Resource-Config information" may be transmitted through one control message or different control messages according to the properties of the configuration information. The beam index information may not clearly represent the index of the transmission beam and the index of the reception beam. For example, the beam index information may be expressed using a reference signal mapped or associated with a corresponding beam index, or an index (or identifier) of a transmission configuration indicator (TCI) state for beam management.

Accordingly, a terminal operating in an RRC connected state can receive a communication service through a beam (eg, a beam pair) established between the terminal and the base station (eg, serving cell). The UE uses a synchronization signal (eg, SS/PBCH block) and/or a reference signal (eg, CSI-RS) transmitted from a base station (eg, serving cell) to search or monitor a radio channel. The operation can be performed. Here, "providing a communication service through a beam (eg, a set beam)" may mean "transmitting and receiving a packet through an activation beam among one or more set beams". In the NR communication system, “the beam is activated” may mean “the configured TCI state is activated”.

The terminal may operate in an RRC idle state or an RRC inactive state. In this case, the UE may perform a downlink channel discovery operation (eg, a monitoring operation) using the parameter(s) obtained from system information or common Resource-Config information. In addition, a terminal operating in an RRC idle state or an RRC inactive state may attempt access using an uplink channel (eg, a random access channel or a physical layer uplink control channel). Alternatively, the terminal may transmit control information using an uplink channel.

The terminal may detect or detect a problem of a radio link by performing a radio link monitoring (RLM) operation. Here, "a problem with the wireless link is detected" may mean "there is an abnormality in setting or maintaining the synchronization of the physical layer for the wireless link". For example, "a problem of a wireless link is detected" may mean "that the physical layer synchronization between the base station and the terminal is not matched during a preset time". When a radio link problem is detected, the terminal may perform a radio link recovery operation. When the radio link is not restored, the terminal may declare a radio link failure (RLF) and may perform a radio link re-establishment procedure.

The radio link physical layer problem detection procedure according to the RLM operation, the radio link recovery procedure, the radio link failure detection (or declaration) procedure, and the radio link re-establishment procedure include the layer of the radio protocol constituting the radio link ( layer) 1 (eg, physical layer), layer 2 (eg, MAC layer, RLC layer, PDCP layer, etc.) and/or layer 3 (eg, RRC layer) functions. have.

The physical layer of the terminal can monitor the radio link by receiving a downlink synchronization signal (eg, a primary synchronization signal (PSS), a secondary synchronization signal (SSS), an SS/PBCH block) and/or a reference signal). I can. In this case, the reference signal is a base station common reference signal, a beam common reference signal, or a dedicated reference signal allocated to a terminal (or terminal group) specific reference signal (eg, a terminal (or terminal group)). dedicated) reference signal). Here, the common reference signal may be used for a channel estimation operation of all terminals located within the coverage (or service area) of a corresponding base station or beam. The dedicated reference signal may be used for a channel estimation operation of a specific terminal or a specific terminal group within the coverage of the base station or the beam.

Accordingly, when the base station or the beam (eg, a set beam between the base station and the terminal) is changed, the dedicated reference signal for beam management may be changed. The beam may be changed based on the configuration parameter(s) between the base station and the terminal. A change procedure for the set beam may be required. “The beam is changed in the NR communication system” means “the index (or identifier) of the TCI state is changed to the index of another TCI state”, “the TCI state is newly set”, or “the TCI state is activated. It can mean "to change to state." The base station may transmit system information including configuration information of the common reference signal to the terminal. The terminal may acquire a common reference signal based on system information. In a handover procedure, a synchronization reconfiguration procedure, or a connection reconfiguration procedure, the base station may transmit a dedicated control message including configuration information of a common reference signal to the terminal.

Information for classifying a base station (eg, cell) may be transmitted to the terminal according to a configuration condition of a radio protocol of the base station. Information for classifying the base station may be delivered to the terminal using a control message of the RRC layer, a control message of the MAC layer, or a control channel of the physical layer according to the layer(s) included in the base station. In embodiments, the control message of the RRC layer may be referred to as "RRC control message" or "RRC message", the control message of the MAC layer may be referred to as "MAC control message" or "MAC message", and the physical layer The control channel may be referred to as “PHY control channel”, “PHY control message”, or “PHY message”.

Here, the information for identifying the base station may include one or more of a base station identifier, reference signal information, reference symbol information, configured beam information, and configuration TCI state information. The reference signal information (or reference symbol information) includes setting information (eg, radio resources, sequence, index) of a reference signal allocated for each base station and/or configuration information of a dedicated reference signal allocated to the terminal (eg, Radio resources, sequences, and indexes) may be included.

Here, the radio resource information of the reference signal indicates time domain resource information (e.g., frame index, subframe index, slot index, symbol index) and frequency domain resource information (e.g., relative or absolute position of a subcarrier). Parameters) can be included. The parameter indicating the radio resource of the reference signal may be a resource element (RE) index, a resource set index, a resource block (RB) index, a subcarrier index, or a symbol index. The RB index may be a physical resource block (PRB) index or a common resource block (CRB) index.

In the following embodiments, the reference signal information includes transmission period information of the reference signal, sequence information (eg, code sequence), masking information (eg, scrambling information), radio resource information, and/or index information. can do. The reference signal identifier may mean a parameter (eg, resource ID, resource set ID) used to distinguish each of a plurality of reference signal information. The reference signal information may mean setting information of a reference signal.

The configuration beam information includes a configuration beam index (or identifier), a configuration TCI state index (or identifier), configuration information of each beam (e.g., transmission power, beam width, vertical angle, horizontal angle), transmission of each beam, and /Or reception timing information (eg, subframe index, slot index, mini-slot index, symbol index, offset), reference signal information corresponding to each beam, and reference signal identifier. In embodiments, the base station may be a base station installed in the air. For example, the base station may be installed on an unmanned aerial vehicle (eg, a drone), a manned aircraft, or a satellite.

The terminal may receive configuration information of the base station (eg, identification information of the base station) from the base station through one or more of an RRC message, a MAC message, and a PHY message, and a beam monitoring operation, a radio access ( access) operation and/or a control (or data) packet transmission/reception operation may be performed.

When a plurality of beams are configured, communication between the base station and the terminal may be performed using a plurality of beams. In this case, the number of downlink beams may be the same as the number of uplink beams. Alternatively, the number of downlink beams may be different from the number of uplink beams. For example, the number of downlink beams may be two or more, and the number of uplink beams may be one.

The base station may obtain the result of the beam measurement operation or the beam monitoring operation from the terminal, and may change the attribute of the beam or the TCI state based on the result of the beam measurement operation or the beam monitoring operation. The beam may be classified into a primary beam, a secondary beam, a spare (or candidate) beam, an active beam, and an inactive beam according to properties. The TCI state may be classified into a primary TCI state, a secondary TCI state, a reserve (or candidate) TCI state, a serving TCI state, a set TCI state, an active TCI state, and an inactive TCI state according to attributes. The TCI state may be assumed to be an active TCI state and a serving TCI state. The reserve (or candidate) TCI state may be assumed to be an inactive TCI state or a set TCI state.

The procedure for changing the beam (or TCI state) attribute may be controlled by the RRC layer and/or the MAC layer. When the procedure for changing the beam (or TCI state) attribute is controlled by the MAC layer, the MAC layer may inform the upper layer of information on the change of the beam (or TCI state) attribute. Information on the change of the beam (or TCI state) attribute may be transmitted to the terminal through a MAC message and/or a physical layer control channel (eg, PDCCH). Information on the change of the beam (or TCI state) attribute may be included in downlink control information (DCI) or uplink control information (UCI). Information on the change of the beam (or TCI state) attribute may be expressed as a separate indicator or field.

The terminal may request a property change of the TCI state based on the result of the beam measurement operation or the beam monitoring operation. The terminal may transmit control information (or feedback information) for requesting the property change of the TCI state to the base station using one or more of a PHY message, a MAC message, and an RRC message. Control information (or feedback information, control message, and control channel) for requesting to change the TCI state attribute may be configured using one or more of the above-described configuration beam information.

Changing the properties of a beam (or TCI state) may mean "change from an active beam to an inactive beam". The procedure for changing the properties of the beam (or TCI state) may be controlled by the RRC layer and/or the MAC layer. The procedure for changing the properties of the beam (or TCI state) may be performed through partial cooperation between the RRC layer and the MAC layer.

When a plurality of beams are allocated, one or more of the plurality of beams may be set as beam(s) for transmitting a physical layer control channel. For example, the primary beam and/or the secondary beam may be used for transmission and reception of a physical layer control channel (eg, a PHY message). Here, the physical layer control channel may be a PDCCH or a PUCCH. The physical layer control channel is scheduling information (e.g., radio resource allocation information, modulation and coding scheme (MCS) information), feedback information (e.g., channel quality indication (CQI), precoding matrix indicator (PMI)), HARQ ACK , HARQ NACK), resource request information (eg, SR (scheduling request)), a result of a beam monitoring operation for supporting a beamforming function, a TCI status ID, and measurement information for an active beam (or an inactive beam) Can be used for more than one transmission.

Radio resource information includes parameter(s) indicating frequency domain resources (e.g., center frequency, system bandwidth, PRB index, number of PBRs, CRB index, number of CRBs, subcarrier index, frequency offset) and time domain resources (For example, a radio frame index, a subframe index, a transmission time interval (TTI), a slot index, a mini-slot index, a symbol index, a time offset, a period of a transmission interval (or a reception interval), a length, Window) may include parameter(s) indicating. In addition, the radio resource information includes a hopping pattern of radio resources, information for beamforming (eg, beam shaping) operation (eg, beam configuration information, beam index), and a code sequence (or bit string). , Signal sequence) may further include resource information occupied according to the characteristics.

The name of the physical layer channel and/or the name of the transport channel is the type of data (or attribute), the type of control information (or attribute), and the transmission direction (e.g., uplink, downlink, sidelink). ), etc.

The beam (or TCI state) or the reference signal for radio link management may be a synchronization signal (eg, PSS, SSS, SS/PBCH block), CSI-RS, PT-RS, SRS, DM-RS, and the like. The reference parameter(s) for the reception quality of a beam (or TCI state) or a reference signal for radio link management is a measurement time unit, a measurement time interval, a reference value indicating the degree of improvement in reception quality, and the degree of degradation in reception quality. It may be a reference value indicated. Each of the measurement time unit and the measurement time period may be set in absolute time (e.g., millisecond, second), TTI, symbol, slot, frame, subframe, scheduling period, base station operation period, or terminal operation period unit. have.

The reference value representing the degree of change in reception quality may be set as an absolute value (dBm) or a relative value (dB). In addition, the reception quality of a beam (or a TCI state) or a reference signal for radio link management is a reference signal received power (RSRP), a reference signal received quality (RSRQ), a received signal strength indicator (RSSI), and a signal-to-signal (SNR). -noise ratio), signal-to-interference ratio (SIR), signal-to-noise and interference ratio (SINR), and the like.

Meanwhile, in an NR communication system using a millimeter frequency band, flexibility in channel bandwidth operation for packet transmission can be secured based on the concept of a bandwidth part (BWP). The base station may set up to 4 BWPs having different bandwidths in the terminal. The BWP can be independently configured in downlink and uplink. That is, the downlink BWP can be distinguished from the uplink BWP. Each of the BWPs may have different bandwidths as well as different subcarrier spacings.

The UE operating in the RRC connected state is a serving cell and a measurement target cell (eg, a neighbor cell, a target cell, a candidate cell, etc.) based on an SS/PBCH block and/or a reference signal (eg, CSI-RS). You can measure the signal quality of your wireless link. Here, the signal quality may be RSRP, RSRQ, RSSI, SNR, SIR, SINR, etc. mentioned in the description related to reception performance of a reference signal for management of the above-described beam (eg, TCI state) or radio link.

The UE operating in the RRC inactive state or the RRC idle state is a serving cell (eg, a camping cell) or a radio link of a measurement target cell according to a DRX period (eg, a measurement period) set based on the SS/PBCH block. The signal quality (eg, RSRP, RSRQ, RSSI, SINR) of can be measured. The terminal may perform a cell selection operation or a cell reselection operation based on the measurement result. For measurement of a serving cell (eg, a camping cell), the UE sets the transmission period of the SS/PBCH block (eg, ssb-PeriodicityServingCell) or the radio resource through which the SS/PBCH is transmitted from the system information of the cell. Information (eg, ssb-PositionsInBurst) may be obtained.

In addition, in order to measure a measurement target cell (eg, a neighboring cell), the terminal may obtain signal measurement time configuration (SMTC) window information from system information. A terminal operating in an RRC inactive state or an RRC idle state may perform a cell selection operation or a cell reselection operation based on a measurement result of SS/PBCH. During the cell selection operation or the cell reselection operation, the terminal may recognize that a radio access network (RAN) area or a tracking area (TA) has changed based on an identifier included in system information received from the cell. In this case, the UE may perform an update procedure of the RAN region or TA.

4 is a conceptual diagram showing a first embodiment of a non-terrestrial network.

Referring to FIG. 4, the non-terrestrial network may include a satellite 410, a communication node 420, a gateway 430, a data network 440, and the like. The non-terrestrial network illustrated in FIG. 4 may be a non-terrestrial network based on a transparent payload. The satellite 410 may be a low earth orbit (LEO) satellite, a medium earth orbit (MEO) satellite, a geostationary earth orbit (GEO) satellite, a high elliptical orbit (HEO) satellite, or an unmanned aircraft system (UAS) platform. The UAS platform may include a high altitude platform station (HAPS). The satellite 410 may mean an unmanned aerial vehicle (UAV) or a UAN base station (UBS).

The communication node 420 may include a communication node (eg, user equipment (UE), terminal) located on the ground and a communication node (eg, airplane, drone) located on the ground. A service link may be established between the satellite 410 and the communication node 420, and the service link may be a radio link. Satellite 410 may provide communication services to communication node 420 using one or more beams. The shape of the footprint of the beam of the satellite 410 may be an elliptical shape. The satellite 410 may provide a communication service to a specific area. For example, the satellite 410 may provide a communication service to a specific area using one beam. One area may exist for each cell, and a plurality of beams may be used in one cell.

The communication node 420 may perform communication (eg, downlink communication, uplink communication) with the satellite 410 using LTE technology and/or NR technology. Communication between the satellite 410 and the communication node 420 may be performed using the NR-Uu interface. When DC (dual connectivity) is supported, the communication node 420 may be connected with not only the satellite 410 but also other base stations (eg, a base station supporting LTE and/or NR functions), and LTE and/or NR DC operation can be performed based on the technology defined in the standard.

The gateway 430 may be located on the ground, and a feeder link may be established between the satellite 410 and the gateway 430. The feeder link may be a wireless link. The gateway 430 may be referred to as a "non-terrestrial network (NTN) gateway". Communication between the satellite 410 and the gateway 430 may be performed based on an NR-Uu interface or a satellite radio interface (SRI). The gateway 430 may be connected to the data network 440. A "core network" may exist between the gateway 430 and the data network 440. In this case, the gateway 430 may be connected to the core network, and the core network may be connected to the data network 440. The core network can support NR technology. For example, the core network may include an access and mobility management function (AMF), a user plane function (UPF), a session management function (SMF), and the like. Communication between the gateway 430 and the core network may be performed based on the NG-C/U interface.

Alternatively, a base station and a core network may exist between the gateway 430 and the data network 440. In this case, the gateway 430 may be connected to the base station, the base station may be connected to the core network, and the core network may be connected to the data network 440. The base station and the core network can support NR technology. Communication between the gateway 430 and the base station may be performed based on the NR-Uu interface, and communication between the base station and the core network (eg, AMF, UPF, SMF) is performed based on the NG-C/U interface. I can.

5 is a conceptual diagram showing a second embodiment of a non-terrestrial network.

Referring to FIG. 5, the non-terrestrial network may include satellite #1 511, satellite #2 512, a communication node 520, a gateway 530, a data network 540, and the like. The non-terrestrial network shown in FIG. 5 may be a non-terrestrial network based on a regenerative payload. For example, satellite #1-2 (511, 512) each of the payload received from another entity (entity) (for example, communication node 520, gateway 530) constituting a non-terrestrial network For example, a regeneration operation (eg, a demodulation operation, a decoding operation, a re-encoding operation, a re-modulation operation, and/or a filtering operation) may be performed, and the regenerated payload may be transmitted.

Each of satellites #1-2 (511, 512) may be an LEO satellite, a MEO satellite, a GEO satellite, a HEO satellite, or a UAS platform. The UAS platform may include HAPS. Each of satellites #1-2 (511, 512) may mean UAV or UBS. Satellite #1 (511) may be connected to satellite #2 (512), and an inter-satellite link (ISL) may be established between satellite #1 (511) and satellite #2 (512). The ISL can operate in a radio frequency (RF) frequency or an optical band. ISL can be set as optional. The communication node 520 may include a communication node (eg, UE, terminal) located on the ground and a communication node (eg, airplane, drone) located on the ground. A service link (eg, a radio link) may be established between the satellite #1 511 and the communication node 520. Satellite #1 511 may provide a communication service to the communication node 520 using one or more beams.

The communication node 520 may perform communication (eg, downlink communication, uplink communication) with satellite #1 511 using LTE technology and/or NR technology. Communication between the satellite #1 511 and the communication node 520 may be performed using the NR-Uu interface. When DC is supported, the communication node 520 may be connected to the satellite #1 511 as well as other base stations (eg, a base station supporting LTE and/or NR functions), and comply with the LTE and/or NR standards. DC operation may be performed based on the defined technology.

The gateway 530 may be located on the ground, a feeder link may be established between the satellite #1 511 and the gateway 530, and a feeder link may be established between the satellite #2 512 and the gateway 530. have. The feeder link may be a wireless link. When the ISL is not set between the satellite #1 511 and the satellite #2 512, a feeder link between the satellite #1 511 and the gateway 530 may be set mandatory.

Communication between each of the satellites #1-2 511 and 5122 and the gateway 530 may be performed based on the NR-Uu interface or SRI. The gateway 530 may be connected to the data network 540. A “core network” may exist between the gateway 530 and the data network 540. In this case, the gateway 530 may be connected to the core network, and the core network may be connected to the data network 540. The core network can support NR technology. For example, the core network may include AMF, UPF, SMF, and the like. Communication between the gateway 530 and the core network may be performed based on the NG-C/U interface.

Alternatively, a base station and a core network may exist between the gateway 530 and the data network 540. In this case, the gateway 530 may be connected to the base station, the base station may be connected to the core network, and the core network may be connected to the data network 540. The base station and the core network can support NR technology. Communication between the gateway 530 and the base station may be performed based on the NR-Uu interface, and communication between the base station and the core network (eg, AMF, UPF, SMF) is performed based on the NG-C/U interface. I can.

Meanwhile, scenarios in a non-terrestrial network may be defined as shown in Table 1 below.

In the case where the satellite 410 in the non-terrestrial network shown in FIG. 4 is a GEO satellite (eg, a GEO satellite supporting a transparent function), it may be referred to as “scenario A”. In the non-terrestrial network shown in FIG. 5, when satellites #1-2 (511, 512) are GEO satellites (eg, GEO supporting regenerative function), this will be referred to as “scenario B”. I can.

In the case where the satellite 410 in the non-terrestrial network shown in FIG. 4 is an LEO satellite having steerable beams, this may be referred to as “scenario C1”. In the case where the satellite 410 in the non-terrestrial network shown in FIG. 4 is an LEO satellite having beams move with satellite, it may be referred to as “scenario C2”. In the case where satellite #1-2 (511, 512) in the non-terrestrial network shown in FIG. 5 is an LEO satellite having adjustable beams, this may be referred to as “scenario D1”. In the case where satellite #1-2 (511, 512) in the non-terrestrial network shown in FIG. 5 is an LEO satellite having beams moving together with the satellite, this may be referred to as “scenario D2”.

Parameters for the scenarios defined in Table 1 may be defined as shown in Table 2 below.

In addition, in the scenarios defined in Table 1, delay constraints may be defined as shown in Table 3 below.

6 is a conceptual diagram showing a third embodiment of a non-terrestrial network.

Referring to FIG. 6, a non-terrestrial network may include a non-terrestrial node 610, terminal #1 621, terminal #2 622, and terminal #3 623. The non-ground node 610 may mean satellite, HAPS, UAV, or UBS. For example, the non-ground node 610 may be a satellite located between about 600 km to 35,000 km from the ground surface. Alternatively, the non-ground node 610 may be a HAPS, UAV, or UBS located between about 10 km to 600 km from the ground surface. The non-ground node 610 may perform a function of a base station or a relay in a terrestrial network (eg, an LTE communication network, an NR communication network). The maximum length of the service area of the non-ground node 610 on the ground surface (eg, the diameter of the service area when the shape of the service area is a circle) may be 500 km. In FIG. 6, X may be the maximum length of the service area of the non-ground node 100.

When the non-terrestrial node 610 is a high altitude geostationary orbit satellite (eg, GEO satellite), approximately in the radio section (L1-L3) between the non-terrestrial node 610 and the terminals 621-623 A transmission delay of 280 ms may occur. The transmission delay may be a round trip delay (RTD) or a propagation delay in the radio section L1-L3. Transmission delay in the radio section (L2) between the non-ground node 610 and the closest terminal #2 (622) and between the non-ground node 610 and the farthest terminal #1 (621) or terminal #3 (623) The difference between transmission delays (hereinafter, "Ldelay_diff") in the radio section L1 or L3 may be about 2 ms.

Each of the transmission delay and Ldelay_diff between the non-ground node 610 and the terminals 621-623 may be much greater than the transmission delay and Ldelay_diff in the terrestrial network. Accordingly, in a non-terrestrial network, each of a control signaling operation, a downlink monitoring operation, a downlink reception operation, and an uplink transmission operation may be performed in consideration of transmission delay and/or Ldelay_diff.

In order for a base station to receive uplink signals of a plurality of terminals without interference in an OFDMA-based communication network, uplink signals transmitted from a plurality of terminals must be aligned in the time domain. Here, the uplink signal may mean a signal including an uplink channel and/or signal. In order to support this operation, the base station may adjust the uplink transmission timing by transmitting timing advance (TA) information to the terminal(s). In a non-terrestrial network, in order to adjust the uplink transmission timing between the non-terrestrial node 610 and the terminals 621-623, a control signaling operation for transmitting TA information may be performed. However, the transmission delay of the radio section (L1-L3) should be considered in the corresponding control signaling operation.

To support this operation, the non-ground node 610 may transmit transmission delay information of the radio section L1-L3 to the corresponding terminal 621-623. Here, the transmission delay information may be minimum transmission delay information (hereinafter referred to as “Ldelay_min information”) in the radio section L2 between the non-ground node 610 and the nearest terminal #2 622. That is, the Ldelay_min information may be transmitted from the non-ground node 610 to the terminals 621-623. Ldelay_min information (e.g., minimum transmission delay value) may be set in units of a symbol, a mini slot, a slot, a sub frame, or a radio frame. have. Alternatively, the Ldelay_min information may be set in absolute time units (eg, ms, sec). The non-ground node 610 is not a minimum transmission delay value (eg, Ldelay_min), but a value representing the transmission delay of the radio section (L1-L3) (eg, Ldelay_ref) to the terminals 621-623 Can be transferred to. In this case, Ldelay_min may be replaced with Ldelay_ref in the following embodiments. That is, Ldelay_min may mean Ldelay_ref.

Before receiving TA information from the non-ground node 610 (for example, "when a random access procedure is not completed" or "when uplink synchronization is not obtained"), the terminals 621-623 are Uplink synchronization information can be obtained from the information. Alternatively, the UEs 621-623 may adjust the UL transmission timing using Ldelay_min (or Ldelay_ref) estimated by the UE itself or the calculated Ldelay_min (or Ldelay_ref). In embodiments, uplink synchronization may mean uplink physical layer synchronization, and uplink transmission timing may mean uplink physical layer transmission timing. Thereafter, the UEs 621-623 may adjust the uplink transmission timing using the TA information received from the non-ground node 610.

The TA information transmitted by the non-ground node 610 may be adjustment information of uplink transmission timing considering Ldelay_min (or Ldelay_ref). For example, when the uplink transmission timing value to be adjusted by the terminals 621-623 is "10" and Ldelay_min (or Ldelay_ref) is "8", the non-ground node 610 is TA information indicating the adjustment of may be transmitted to the terminal 621-623.

The terminals 621-623 may adjust the uplink transmission timing based on the Ldelay_min and/or TA information received from the non-ground node 610. A parameter for management of uplink transmission timing may be set to " timeAlignmentTimer ". When a message including TA information (eg, a MAC message or a random access (RA) response message) is received from the non-ground node 610, the terminal may (re)start the timeAlignmentTimer . When a message including TA information is not received before the expiration of timeAlignmentTimer , the UEs 621-623 may determine that uplink synchronization maintenance has failed. In this case, the UEs 621-623 may perform a synchronization acquisition procedure (eg, an RA procedure) for uplink transmission.

The Ldelay_min (or Ldelay_ref) information may be set differently according to the type and altitude of the non-ground node 610. The non-ground node 610 may transmit system information including Ldelay_min (or Ldelay_ref) information or other control message (eg, a MAC control message or a PHY control message) to the terminals 621-623. That is, Ldelay_min (or Ldelay_ref) information may be signaled in an explicit manner through system information. Alternatively, the terminals 621-623 may estimate or calculate Ldelay_min (or Ldelay_ref) in an implicit method. For example, the non-ground node 610 may transmit system information including its type information, altitude information, and the like to the terminals 621-623. The terminals 621-623 may receive system information from the non-ground node 610, and are based on information included in the system information (eg, type information of the non-ground node 610, altitude information). Thus, Ldelay_min (or Ldelay_ref) can be estimated or calculated. The type information of the non-ground node 610 may indicate that the non-ground node 610 is a satellite, HAPS, UAV, or UBS.

Terminals 621-623 based on the setting information (eg, type information, altitude information) of the non-ground node 610, the non-ground node 610 is a GEO satellite, non-GEO satellite ( For example, it may be determined as LEO satellite, MEO satellite, HEO satellite), HAPS, UAV, or UBS. Information used to identify the non-ground node 610 may be transmitted from the non-ground node 610 to the terminals 621-623 through system information and/or control messages. The altitude information of the non-ground node 610 is “information indicating the actual altitude of the non-ground node 610” or “information indicating the altitude classification to which the actual altitude of the non-ground node 610 belongs (for example, For example, it could be "low altitude, medium and high altitude)". The altitude information of the non-ground node 610 may be transmitted from the non-ground node 610 to the terminals 621-623 through system information and/or control messages. The terminals 621-623 may estimate or calculate Ldelay_min (or Ldelay_ref) based on configuration information (eg, type information, altitude information) received from the non-ground node 610.

Alternatively, the terminal (621-623) is the identifier of the non-ground node 610 (for example, an identifier for cell classification (for example, PCI (physical cell identifier)), an identifier for beam classification) Can be used to estimate or calculate Ldelay_min (or Ldelay_ref). PCI may be set differently according to the type and/or altitude of the non-ground node 610. Accordingly, the terminals 621-623 can check the type and/or altitude of the non-ground node 610 based on the PCI received from the non-ground node 610, and estimate Ldelay_min based on the checked information or Can be calculated. That is, the terminals 621-623 may estimate or calculate Ldelay_min using the configuration information and/or the identifier of the non-ground node 610. The non-ground node 610 may provide a communication service to the terminals 621-623 using a plurality of beams or a plurality of frequency resources. In this case, Ldelay_min of non-ground nodes located at the same altitude or non-ground nodes of the same type may have the same value.

7 is a timing diagram illustrating a first embodiment of a discontinuous reception (DRX) operation in a terminal operating in an RRC connected state.

Referring to FIG. 7, the terminal may be connected to a non-ground node or a ground node (eg, a base station), and may operate in an RRC connected state. In embodiments, a non-terrestrial node may mean satellite, HAPS, UAV, or UBS. Further, the non-ground node may mean a base station installed in a non-ground node, a cell formed by a non-ground node, and the like. Each of a non-terrestrial node, a base station, and a cell logically connected to the terminal may mean a serving non-ground node, a serving base station, and a serving cell. The non-ground node may provide a communication service to the terminal. A terminal operating in an RRC connected state may perform a DRX operation to reduce power consumption.

The non-ground node uses a DCI including downlink scheduling information (eg, information indicating downlink reception) or uplink scheduling information (eg, information indicating uplink transmission) to a control channel (eg, For example, it may be transmitted to the terminal through PDCCH (S701). A terminal operating in an RRC connected state may receive DCI from a non-ground node by performing a monitoring operation in a control channel.

Alternatively, the non-ground node may transmit downlink data to the terminal using a preset resource (eg, periodic resource) (S701). The terminal may receive downlink data from a non-ground node by performing a monitoring operation on a preset resource. Alternatively, the terminal may transmit uplink data to a non-ground node using a preset resource (eg, periodic resource) (S701). The non-ground node may receive uplink data from the terminal by performing a monitoring operation on a preset resource. Here, the preset resource may be a resource set according to a semi-persistent scheduling (SPS) method or a configured grant (CG) method.

In embodiments, step S701 may be referred to as “DL/UL communication operation”, and the DL/UL communication operation is “DCI using PDCCH (eg, DCI including downlink scheduling information or uplink scheduling information). )", "a transmission operation of downlink data using a preset resource", or "a transmission operation of uplink data using a preset resource". "A transmission operation of downlink data using a preset resource" may include "a transmission/reception operation of an indicator requesting activation of a preset resource (eg, an SPS resource)". The “transmission operation of uplink data using a preset resource” may include “a transmission/reception operation of an indicator requesting activation of a preset resource (eg, CG resource)”.

The terminal may (re)start an inactivity timer for the DRX operation at a time point of a DL/UL communication operation (eg, a start time point or a peer time point) (S702). The timing of the DL/UL communication operation is the DCI reception start point, the DCI reception end point, the downlink data reception start point, the downlink data reception end point, the uplink data transmission start point, or uplink data transmission. May be the end point. In embodiments, the inactivity timer may be referred to as an Inact-timer. When other DL/UL communication operations are not performed until the inact-timer expires, the UE may perform the DRX operation according to a preset DRX cycle (S703). The DRX cycle may include on duration and an opportunity for DRX (opportunity for DRX). The UE may perform a downlink monitoring operation in the on-duration, and may not perform a downlink monitoring operation in a DRX opportunity. In embodiments, the DRX opportunity may be referred to as a “sleep period”. The terminal can operate in a sleep state in the sleep period.

A terminal operating in an RRC connected state may perform a DRX operation. In this case, the UE may repeatedly perform an operation (eg, a downlink monitoring operation) and an operation (eg, a sleep operation) in the on-duration according to the DRX cycle. The terminal may set a timer for the on duration (hereinafter referred to as “on duration timer”), and may (re)start the on duration timer at the start of the on duration. The terminal may determine the time when the on duration timer expires as the end time of the on duration.

When the DL/UL communication operation is performed in on-duration #2 (eg, point A in on-duration #2), the terminal may (re)start Inact-timer and H-RTT-timer (S704). The H-RTT-timer may be set in a downlink HARQ process unit or an uplink HARQ process unit. For example, the H-RTT-timer may be independently set for each HARQ process identifier (ID) or HARQ process number. In downlink communication, H-RTT-timer may be defined as “drx-HARQ-RTT-TimerDL”, and in uplink communication H-RTT-timer may be defined as “drx-HARQ-RTT-TimerUL”. In embodiments, drx-HARQ-RTT-TimerDL may be referred to as H-RTT-TimerDL, and drx-HARQ-RTT-TimerUL may be referred to as H-RTT-TimerUL.

H-RTT-TimerDL may indicate a minimum time required to allocate downlink resources for HARQ retransmission. H-RTT-TimerUL may indicate the minimum time required to allocate uplink resources for HARQ retransmission. H-RTT-TimerDL and H-RTT-TimerUL may be (re)started in the following case(s).

-Case 1: When the PDCCH (eg, DCI transmitted through the PDCCH) instructs to perform a downlink reception operation or an uplink transmission operation

-Case 2: When downlink data or uplink data is transmitted/received from a preset resource (eg, SPS resource or CG resource)

At the expiration point of H-RTT-TimerDL or H-RTT-TimerUL (eg, point B), the terminal may (re)start ReTx-timer (S705). When the DL/UL communication operation fails in the on-duration, the ReTx-timer may (re)start for the DL/UL communication operation for retransmission. For example, "When ACK (acknowledgement) for data is not received in the time interval according to H-RTT-timer" or "NACK (negative ACK) for data is received in the time interval according to H-RTT-timer. If "is", the terminal may (re)start the ReTx-timer.

The ReTx-timer may be set in a downlink HARQ process unit or an uplink HARQ process unit. For example, ReTx-timer may be independently set for each HARQ process ID or HARQ process number. In downlink communication, ReTx-timer may be defined as "drx-RetransmissionTimerDL", and in uplink communication, ReTx-timer may be defined as "drx-RetransmissionTimerUL". In embodiments, drx-RetransmissionTimerDL may be referred to as “ReTx-TimerDL”, and drx-RetransmissionTimerUL may be referred to as “ReTx-TimerUL”.

The ReTx-TimerDL may be a timer indicating an effective monitoring period for a control channel (eg, PDCCH) indicating activation of downlink resource allocation or downlink resource (eg, SPS resource) for HARQ retransmission. . ReTx-TimerUL may be a timer indicating an effective monitoring period for a control channel (eg, PDCCH) indicating activation of uplink resource allocation or uplink resource (eg, CG resource) for HARQ retransmission. . ReTx-TimerDL can (re)start when H-RTT-TimerDL expires, and ReTx-TimerUL can (re)start when H-RTT-TimerUL expires. Each of ReTx-TimerDL and ReTx-TimerUL may be stopped in the following case(s).

-Case 1: When the PDCCH (eg, DCI transmitted through the PDCCH) instructs to perform a downlink reception operation or an uplink transmission operation

-Case 2: When a downlink communication operation or an uplink communication operation is performed in a preset resource (eg, SPS resource or CG resource)

For example, when a DL/UL communication operation (e.g., a DL/UL communication operation for retransmission) is performed in a time interval according to ReTx-TimerDL or ReTx-TimerUL (e.g., time D), the terminal ReTx-TimerDL or ReTx-TimerUL can be stopped. That is, if the DL/UL communication operation is performed before the expiration time of ReTx-TimerDL or ReTx-TimerUL (e.g., time E), the terminal performs ReTx at the time when the DL/UL communication operation is performed (e.g., time D). -TimerDL or ReTx-TimerUL can be stopped. In this case, the time interval from the start point of on-duration #2 (e.g., point S) to the stop point of ReTx-TimerDL or ReTx-TimerUL (e.g., point D) is defined as an active time. Can be.

When the DL/UL communication operation fails in on-duration #2, a DL/UL communication operation for retransmission may be performed after the on-duration #2 ends. In this case, the UE performs a downlink monitoring operation during an active time from the start point of the on duration #2 (e.g., point S) to the end point of the DL/UL communication operation for retransmission (e.g., point D). Can be done. "When the inact-timer expires" or "when the active time (for example, an active time related timer) expires", the terminal may perform a DRX operation according to a preset DRX cycle or DRX parameter(s). .

In the above-described DRX operation or a DRX operation to be described later, the non-ground node may set timers (eg, Inact-timer, H-RTT-timer, ReTx-Timer), and set timers are RRC messages, MAC messages, And a combination of one or more of the PHY messages may be used to inform the UE. For example, before step S701 (or before step S801), the non-ground node is an RRC message including information of timers (eg, Inact-timer, H-RTT-timer, ReTx-Timer), MAC A message, and/or a PHY message may be transmitted to the terminal. The UE can check timers (eg, Inact-timer, H-RTT-timer, ReTx-timer) by receiving an RRC message, a MAC message, and/or a PHY message from a non-ground node, and the confirmed timer DRX operations can be performed using (s).

Meanwhile, in the DRX operation illustrated in FIG. 7, in the non-terrestrial network illustrated in FIG. 6, a transmission delay parameter (hereinafter, referred to as “Ldelay_value”) may be considered in a radio section between a non-ground node and a terminal. Ldelay_value is Ldelay_min (or Ldelay_ref), the transmission delay in the radio section estimated (e.g., measured) or calculated by the non-ground node, or the transmission delay in the radio section estimated (e.g., measured) or calculated by the terminal Can be

8 is a timing diagram showing a first embodiment of a DRX operation in a non-terrestrial network.

Referring to FIG. 8, a terminal may be connected to a non-ground node and may operate in an RRC connected state. In embodiments, a non-terrestrial node may mean satellite, HAPS, UAV, or UBS. Further, the non-ground node may mean a base station installed in a non-ground node, a cell formed by a non-ground node, and the like. Each of a non-ground node, a base station, and a cell logically connected to the terminal may mean a serving non-ground node, a serving base station, and a serving cell. The non-ground node may provide a communication service to the terminal. A terminal operating in an RRC connected state may perform a DRX operation to reduce power consumption.

The H-RTT-timer (hereinafter referred to as "non-terrestrial H-RTT-timer") used in the non-terrestrial network may be set in consideration of Ldelay_value. H-RTT-timer used in a terrestrial network (eg, 4G communication network, 5G communication network) may be referred to as “terrestrial H-RTT-timer”. For example, the H-RTT-timer shown in FIG. 7 may be a terrestrial H-RTT-timer. The non-ground H-RTT-timer (eg, non-ground H-RTT-TimerDL, non-ground H-RTT-TimerUL) may be set to a value greater than Ldelay_value or Ldelay_value. Alternatively, the non-ground H-RTT-timer may be set based on the sum of the ground H-RTT-timer and Ldelay_value. Or, the non-terrestrial H-RTT-timer is set by additionally considering the "sum of the terrestrial H-RTT-timer and Ldelay_value" and the transmission delay deviation (eg, Ldelay_diff) between the non-ground node and a plurality of terminals. Can be. For example, the non-ground H-RTT-timer may be set based on Equation 1 or Equation 2 below.

The non-ground H-RTT-timer may be set in the non-ground node. The non-ground node may inform the terminal of the non-ground H-RTT-timer through a combination of one or more of an RRC message, a MAC message, and a PHY message. The terminal may check the non-terrestrial H-RTT-timer by receiving an RRC message, a MAC message, and/or a PHY message from a non-ground node. Alternatively, the non-terrestrial H-RTT-timer may be configured in the terminal. For example, the terminal may determine the non-terrestrial H-RTT-timer based on Equation 1. The terrestrial H-RTT-timer and/or Ldelay_value may be signaled from the non-ground node to the terminal. Alternatively, the terrestrial H-RTT-timer may be determined by the terminal, and Ldelay_value may be a value measured (eg, estimated) or calculated by the terminal.

For the efficiency of DRX operation in a non-terrestrial network, the non-terrestrial H-RTT-timer (e.g., non-terrestrial H-RTT-TimerDL, non-terrestrial H-RTT-TimerUL) is the DRX cycle (or on Duration, DRX opportunity). The non-ground H-RTT-timer may be set such that the end point of the time period according to the non-ground H-RTT-timer is located within the on duration according to the DRX period. Alternatively, the non-ground H-RTT-timer may be set so that the end time of the time interval according to the non-ground H-RTT-timer is aligned with the start or end time of the on-duration according to the DRX cycle.

The non-ground node uses a DCI including downlink scheduling information (eg, information indicating downlink reception) or uplink scheduling information (eg, information indicating uplink transmission) to a control channel (eg, For example, it may be transmitted to the terminal through PDCCH (S801). A terminal operating in an RRC connected state may receive DCI from a non-ground node by performing a monitoring operation in a control channel. When other DL/UL communication operations are not performed in the time interval from the completion of the downlink communication operation or the uplink communication operation indicated by the DCI to the end of the inact-timer, the terminal performs DRX according to a preset DRX cycle. The operation can be performed (S802). In this case, the UE may perform a downlink monitoring operation in on-duration #1, and may not perform a downlink monitoring operation in DRX opportunity #1 (eg, sleep period #1). For example, the terminal may operate in a sleep state in sleep period #1.

On the other hand, when the DL/UL communication operation is performed in on-duration #2 (eg, point A in on-duration #2), the terminal may (re)start the Inact-timer and the H-RTT-timer (S803 ). The H-RTT-timer may be set in a downlink HARQ process unit or an uplink HARQ process unit. For example, H-RTT-timer may be independently set for each HARQ process ID or HARQ process number. The H-RTT-Timer may indicate the minimum time required to allocate resources for HARQ retransmission in a non-terrestrial network. H-RTT-Timer is "when the PDCCH (eg, DCI transmitted through the PDCCH) instructs to perform a downlink reception operation or an uplink transmission operation" or "a preset resource (eg, an SPS resource or CG resource) may start when downlink data or uplink data is transmitted/received.

If no other DL/UL communication operation is performed in the time interval from the point A to the end point of the inact-timer, and the on-duration #2 is terminated, the terminal performs DRX based on a preset DRX cycle and DRX parameter(s). The operation can be performed. Here, the DRX operation may be performed in a time interval according to the H-RTT-timer. The terminal may (re)start the ReTx-timer at the end of the H-RTT-timer (S804). When the DL/UL communication operation fails in on-duration #2, the ReTx-timer may (re)start for the DL/UL communication operation for retransmission. For example, "when an ACK for data is not received in a time interval according to H-RTT-timer" or "when a NACK for data is received in a time interval according to H-RTT-timer", the terminal is ReTx -timer can be (re)started.

The terminal may perform a downlink monitoring operation in a section according to the ReTx-timer. ReTx-timer may be set in a downlink HARQ process unit or an uplink HARQ process unit in a non-terrestrial network. For example, ReTx-timer may be independently set for each HARQ process ID or HARQ process number.

When the end point of the H-RTT-timer is located within the sleep period #n prior to the on-duration #n+1, the terminal sleeps before the start point of the on-duration #n+1 (eg, S-2) The downlink monitoring operation may be performed from the point B within the interval #n. Here, n may be an integer of 3 or more. The UE may determine that a DL/UL communication operation for retransmission has occurred by performing a downlink monitoring operation. The DL/UL communication operation for retransmission may be a retransmission operation for a DL/UL communication operation that fails in on-duration #2. In this case, the terminal may (re)start the Inact-timer at a time when a DL/UL communication operation for retransmission occurs (eg, time D) (S805). In addition, the terminal may end the ReTx-timer at time D.

If the DL/UL communication operation for retransmission is successfully completed, and no other DL/UL communication operation occurs within the period from the point D to the end of the inact-timer, the terminal is DRX operation may be performed based on the set DRX cycle and DRX parameter(s). Here, the active time may be a time interval from the start point of the downlink monitoring operation (eg, point B) to the end point of the on duration #n+1 (eg, point F).

Meanwhile, the following items may be additionally considered in the relationship between the retransmission operation according to HARQ and the DRX operation.

-Downlink radio resource bundling allocation

-Uplink radio resource bundling allocation

-HARQ deactivation (disable or deactivation) function

In the bundling assignment of a downlink radio resource or an uplink radio resource, a DL/UL communication operation (e.g., step S701, step S801) is performed by a plurality of radio resources (e.g., a plurality of slots) according to a plurality of scheduling periods. S) can mean the case. For example, the DL/UL communication operation may be performed based on a repetition scheduling scheme. When the bundling allocation method (or repetitive scheduling method) is used, H-RTT-timer shown in FIG. 7 (eg, terrestrial H-RTT-timer) and H-RTT-timer shown in FIG. 8 (eg For example, the (re)start operation or stop operation of each of the non-ground H-RTT-timer) and ReTx-timer may not be performed.

For example, the terminal inact-timer at the end point (e.g., the last occurrence point) of the DL/UL communication operation (e.g., step S701, step S801) according to the bundling allocation method (or repetitive scheduling method). Can start. "When a downlink reception operation or an uplink transmission operation is not performed until the expiration of the Inact-timer" or "when the on duration (eg, on duration #2 shown in FIG. 8) is terminated", the terminal A DRX operation may be performed based on a preset DRX cycle and DRX parameter(s). Here, the end point (e.g., the last occurrence point) of the DL/UL communication operation according to the bundling allocation method (or repetitive scheduling method) is "DL/UL communication operation according to the last bundling allocation (or last repetitive scheduling). It may be a time point of" or "a downlink reception time point (or an uplink transmission time point) according to the last repetitive scheduling (or last bundling assignment)".

The HARQ deactivation function may mean that the HARQ function is deactivated in a data transmission procedure between a non-ground node and a terminal. The HARQ deactivation function may be applied in units of HARQ processes (eg, HARQ process ID or HARQ process number), in units of logical channels, units of transport blocks, or units of code blocks. Even when the HARQ function is deactivated in the data transmission procedure, H-RTT-timer shown in FIG. 7 (eg, terrestrial H-RTT-timer) and H-RTT-timer shown in FIG. 8 (eg, Non-ground H-RTT-timer), and/or ReTx-timer, each (re)start operation or stop operation may not be performed. When the HARQ function is deactivated, the terminal may start the Inact-timer at the time when the DL/UL communication operation is performed. "When the downlink reception operation or the uplink transmission operation is not performed until the expiration of the Inact-timer" or "when the on duration (eg, on duration #2 shown in FIG. 8) ends", the terminal A DRX operation may be performed based on a preset DRX cycle and DRX parameter(s).

Meanwhile, a DRX operation for reducing power consumption of a terminal in a non-terrestrial network may be performed based on a control message instead of the timer(s) shown in FIGS. 7 and 8. For example, the non-ground node may transmit a PHY message and/or a MAC message indicating the performance of the DRX operation to the terminal. The PHY message may be a DCI transmitted through the PDCCH. A specific field included in the DCI may indicate the execution of the DRX operation. Alternatively, the PHY message may be a reference signal indicating the execution of the DRX operation. Each of the PHY message and the MAC message indicating the execution of the DRX operation may include information indicating the time when the DRX operation is performed. Information indicating the time point at which the DRX operation is performed may indicate the start time point of the on-duration. Alternatively, the information indicating the time point at which the DRX operation is performed may indicate an offset between a time point at which a control message (eg, a PHY message, a MAC message) including the corresponding information is received and a time point at which the on duration starts. Information indicating the time point at which the DRX operation is performed may be set in units of slots, minislots, slots, subframes, or radio frames. Alternatively, information indicating a time point at which the DRX operation is performed may be set in absolute time units (eg, milliseconds, microseconds).

The terminal may receive a control message instructing to perform a DRX operation from a non-ground node, and use of a timer (eg, Inact-timer, H-RTT-timer) for the DRX operation (eg, ( Re) It is possible to perform a DRX operation using a preset DRX cycle and DRX parameter(s) without starting, running, and stopping). In this case, the UE may perform a downlink monitoring operation within the on-duration according to the DRX period in order to receive downlink data. The non-ground node may perform a DL/UL communication operation in on-duration according to the DRX cycle. The control message indicating the execution of the DRX operation may indicate to perform the DRX operation at the end of the DL/UL communication operation. Here, the end time of the DL/UL communication operation may be the same as the start time of the DRX operation. Alternatively, the control message instructing the execution of the DRX operation may indicate to perform the DRX operation when the on-duration ends after the DL/UL communication operation is completed.

The above-described timers, offsets, counters, time intervals, and time periods (e.g., start time, restart time, end time, stop time) are set in units of symbols, mini slots, slots, subframes, or radio frames. Can be. Alternatively, timers, offsets, counters, time intervals, and time points for each period (e.g., start point, restart point, end point, stop point) are set in absolute time units (e.g., milliseconds, microseconds). Can be.

Meanwhile, the above-described non-ground node (eg, non-ground cell) may be a base station. Non-ground nodes are NodeB, evolved NodeB, base transceiver station (BTS), radio base station, radio transceiver, access point, and access node. It may be referred to as (node), road side unit (RSU), radio remote head (RRH), transmission point (TP), transmission & reception point (TRP), or gNB.

In the present invention, a terminal is a UE, a terminal, an access terminal, a mobile terminal, a station, a subscriber station, a mobile station, and a portable subscriber station. It may be referred to as a subscriber station), a node, a device, an Internet of Thing (IoT) device, or a mounted module/device/terminal or on board device/terminal.

The methods according to the present invention may be implemented in the form of program instructions 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 recorded on the 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 not only machine language codes such as those produced by a compiler, but also high-level language codes that can be executed by a computer using an interpreter or the like. The above-described hardware device may be configured to operate as at least one software module to perform the operation of the present invention, and vice versa.

Although described with reference to the above embodiments, those skilled in the art will understand that various modifications and changes can be made to the present invention without departing from the spirit and scope of the present invention described in the following claims. I will be able to.

Claims (20)

As a method of operating a terminal in a non-terrestrial network,
When a transmission operation of downlink data is started in an on duration according to a discontinuous reception (DRX) period, a first timer indicating a first time interval required for the retransmission operation of the downlink data is set. Starting step;
Starting a second timer at the end of the first timer;
Performing a downlink monitoring operation in a second time interval according to the second timer; And
When control information for the retransmission operation is received from a non-ground node in the second time interval, receiving the downlink data from the non-ground node in a downlink resource indicated by the control information And
The first timer is set in consideration of a transmission delay between the non-ground node and the terminal. The method according to claim 1,
The first timer is set in units of a hybrid automatic repeat request (HARQ) process in the non-terrestrial network. The method according to claim 1,
The first time period is a minimum time period required to allocate the downlink resource for the retransmission operation in the non-terrestrial network. The method according to claim 1,
The length of the first time period is set as a multiple of the DRX period. The method according to claim 1,
The end point of the first time period is set to a start point of the on-duration, an end point of the on-duration, or an arbitrary point in the on-duration. The method according to claim 1,
The first time period is a sum of the transmission delay and a minimum time period required to allocate the downlink resource for the retransmission operation in a terrestrial network. The method according to claim 1,
When the transmission operation is successfully completed, the first timer is stopped, and when the transmission operation fails, the first timer continues to operate. The method according to claim 1,
When the control information for the retransmission operation is received from the non-ground node, the second timer is stopped. The method according to claim 1,
The operating method of the terminal,
Receiving a message including the information of the first timer and the information of the second timer from the non-ground node, the method of operating the terminal. As a terminal in a non-terrestrial network,
Processor;
A memory in electronic communication with the processor; And
Contains instructions stored in the memory,
When the instructions are executed by the processor, the instructions are the terminal,
When a transmission operation of uplink data starts in an on duration according to a discontinuous reception (DRX) period, a first timer indicating a first time period required for the retransmission operation of the uplink data is set. Starting;
Starting a second timer at the end of the first timer; And
Operates to cause retransmission of the uplink data to a non-ground node using uplink resources within a second time interval according to the second timer,
The first timer is set in consideration of a transmission delay between the non-ground node and the terminal. The method of claim 10,
The first timer is set in units of a hybrid automatic repeat request (HARQ) process in the non-terrestrial network. The method of claim 10,
The first time period is a minimum time period required to allocate the uplink resource for the retransmission operation in the non-terrestrial network, and the length of the first time period is set as a multiple of the DRX period. The method of claim 10,
The terminal, wherein the end point of the first time period is set to a start point of the on-duration, an end point of the on-duration, or an arbitrary point in the on-duration. The method of claim 10,
The first time period is a sum of the transmission delay and a minimum time period required to allocate the uplink resource for the retransmission operation in a terrestrial network. The method of claim 10,
The uplink resource is a radio resource or a configured grant (CG) resource indicated by downlink control information (DCI) received from the non-ground node in the second time interval. The method of claim 10,
The above commands are:
The terminal further executed to cause receiving from the non-ground node a message comprising information of the first timer and information of the second timer. As a method of operating a non-terrestrial node in a non-terrestrial network,
A message including information on a first timer indicating a first time period required for a retransmission operation of downlink data and a second timer indicating a second time period in which the downlink monitoring operation is performed is sent to the terminal Transferring to;
Performing a transmission operation of the downlink data in an on duration according to a discontinuous reception (DRX) period; And
When the transmission operation fails, transmitting control information for the retransmission operation to the terminal in the second time interval after the first time interval,
The first time interval starts from a time point when the transmission operation is performed, the second time interval starts from an end time point of the first time interval, and the first timer is a transmission delay between the non-ground node and the terminal. The operation method of the non-ground node is set in consideration of. The method of claim 17,
The first time period is a minimum time period required to allocate the downlink resource for the retransmission operation in the non-terrestrial network, and the length of the first time period is set as a multiple of the DRX period, non-ground How the node works. The method of claim 17,
The method of operating a non-ground node, wherein the end point of the first time period is set to a start point of the on-duration, an end point of the on-duration, or an arbitrary point in the on-duration. The method of claim 17,
The first time period is the sum of the transmission delay and the minimum time period required to allocate the downlink resource for the retransmission operation in the terrestrial network.

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