KR102443745B1 - Method and apparatus for retransmission in communication system - Google Patents

Abstract

A method and apparatus for retransmission in a communication network are disclosed. The operating method of the first communication node includes receiving one or more TBs from a second communication node based on a transmission parameter in an aggregated transmission interval #n, generating decoding results for the one or more TBs, the decoding generating information necessary for changing the transmission parameter based on the results, and transmitting the necessary information to the second communication node.

Description

METHOD AND APPARATUS FOR RETRANSMISSION IN COMMUNICATION SYSTEM

The present invention relates to a retransmission technique in a communication network, and more particularly, to a channel adaptive control technique in a blind retransmission procedure.

For processing of rapidly increasing wireless data, a frequency band (eg, a frequency band of 6 GHz or more) higher than a frequency band (eg, a frequency band of 6 GHz or less) of long term evolution (LTE) (or LTE-A) A communication network (eg, a new radio (NR) communication network) using The NR communication network may support a frequency band of 6 GHz or higher as well as a frequency band of 6 GHz or less, and may 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), massive Machine Type Communication (mMTC), and the like.

The NR communication network may provide a communication service to terminals located in terrestrial. Recently, as well as on the ground, the demand for communication services for airplanes, drones, satellites, etc. located in non-terrestrial is increasing, and for this purpose, non-terrestrial network (NTN) ) are being discussed. Non-terrestrial networks may be implemented based on NR technology. For example, in a non-terrestrial network, communication between a satellite and a communication node located on the ground (eg, user equipment (UE)) or a communication node located on a non-terrestrial (eg, airplane, drone) is based on the NR technology. It can be done based on In a non-terrestrial network, a satellite may perform the function of a base station in an NR communication network.

Meanwhile, in a communication network (eg, an LTE communication network, an NR communication network, and a non-terrestrial network), data may be transmitted based on a blind retransmission scheme. In this case, a hybrid automatic repeat request (HARQ) response to data (eg, acknowledgment (ACK) or negative ACK (NACK)) may not be transmitted. Since a transmitting node (eg, a base station or a terminal) that has transmitted data does not receive an HARQ response for the corresponding data, it may not be able to accurately check the link state (eg, throughput). Therefore, resources may be wasted in the data transmission procedure.

An object of the present invention for solving the above problems is to provide a method and apparatus for retransmission based on statistical information on a result of decoding data.

In order to achieve the above object, a method of operating a first communication node according to a first embodiment of the present invention includes the steps of receiving one or more TBs from a second communication node based on a transmission parameter in an aggregated transmission interval #n, the generating decoding results for one or more TBs, generating information necessary for changing the transmission parameter based on the decoding results, and transmitting the necessary information to the second communication node and n is a natural number.

Here, the operating method of the first communication node includes receiving, from the second communication node, a transmission parameter changed in consideration of the necessary information, and one based on the changed transmission parameter in an aggregated transmission section #n+k The method may further include receiving the above TBs from the second communication node, where k may be a natural number.

Here, in the method of operating the first communication node, when the number of the one or more TBs is the same as the number of a plurality of slots included in the aggregated transmission interval #n, the one or more TBs at a time specified by the second communication node The method may further include transmitting a HARQ response for the above TBs to the second communication node.

Here, the necessary information may be transmitted to the second communication node when a feedback condition is satisfied.

Here, the aggregated transmission interval #n may include one or more slots, and the one or more TBs received in the aggregated transmission interval #n may be generated based on the same data unit.

Here, the necessary information may be statistical information indicating the number of decoding successes or decoding failures occurring in the aggregated transmission interval #n.

Here, the necessary information may be statistical information indicating the number of decoding successes or decoding failures occurring in one or more aggregated transmission intervals.

Here, the necessary information may be information indicating that the transmission parameter is not efficient.

Here, the necessary information may be a guideline for changing the transmission parameter.

A method of operating a second communication node according to a second embodiment of the present invention for achieving the above object includes the steps of transmitting a transmission parameter to the first communication node, one based on the transmission parameter in an aggregated transmission interval #n Transmitting the above TBs to the first communication node, receiving information necessary for changing the transmission parameter from the first communication node, changing the transmission parameter in consideration of the necessary information, and changed transmission transmitting a parameter to the first communication node, wherein the necessary information is generated based on decoding results for the one or more TBs, wherein n is a natural number.

Here, the method of operating the second communication node may further include transmitting one or more TBs to the first communication node based on the changed transmission parameter in an aggregated transmission interval #n+k, wherein the k may be a natural number.

Here, the necessary information may be received from the first communication node when a feedback condition is satisfied.

Here, the aggregated transmission interval #n may include one or more slots, and the one or more TBs transmitted in the aggregated transmission interval #n may be generated based on the same data unit.

Here, the necessary information may be statistical information indicating the number of decoding successes or decoding failures occurring in one or more aggregated transmission intervals.

Here, the necessary information may be information indicating that the transmission parameter is not efficient or a guideline for changing the transmission parameter.

In order to achieve the above object, the method of operating a first communication node according to a third embodiment of the present invention includes the steps of receiving a first TB from a second communication node based on a transmission parameter, and a decoding result for the first TB generating, generating information necessary for changing the transmission parameter based on the decoding result, transmitting the necessary information to the second communication node, to the first TB based on the decoding result generating a HARQ response for , and transmitting the HARQ response to the second communication node, wherein n is a natural number.

Here, the operating method of the first communication node includes receiving, from the second communication node, a transmission parameter changed in consideration of the necessary information, and receiving a second TB from the second communication node based on the changed transmission parameter. The method may further include receiving, where k may be a natural number.

Here, the necessary information may be transmitted to the second communication node when a feedback condition is satisfied.

Here, the necessary information may be information indicating that the transmission parameter is not efficient or a guideline for changing the transmission parameter.

According to the present invention, a receiving node (eg, a base station or a terminal) transmits statistical information about a data decoding result, efficiency information of a transmission parameter, and/or guide information of a transmission parameter to a transmitting node (eg, a terminal or base station). The transmitting node may reset the transmission parameters based on statistical information, efficiency information, and/or guide information received from the receiving node. Communication between the transmitting node and the receiving node may be performed based on the reset transmission parameter. Therefore, reliability can be guaranteed in the retransmission procedure, and resource waste can be prevented. That is, the performance of the communication system may be improved.

1 is a conceptual diagram illustrating a first embodiment of a non-terrestrial network.
2 is a conceptual diagram illustrating a second embodiment of a non-terrestrial network.
3 is a block diagram illustrating a first embodiment of entities constituting a non-terrestrial network.
4 is a conceptual diagram illustrating a first embodiment of a blind retransmission method in a communication system.
5 is a flowchart illustrating a first embodiment of a retransmission method in a communication system.
6 is a flowchart illustrating a second embodiment of a retransmission method in a communication system.
7 is a conceptual diagram illustrating a first embodiment of SAF required according to a data decoding result in a communication system.
8 is a flowchart illustrating a third embodiment of a retransmission method in a communication system.
9 is a flowchart illustrating a fourth embodiment of a retransmission method in a communication system.
10 is a flowchart illustrating a fifth embodiment of a retransmission method in a communication system.

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

Terms such as first, second, etc. may be used to describe various elements, but the elements should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component. 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 may be directly connected or connected to the other component, but it is understood that other components may exist in between. it should be On the other hand, when it is said that a certain element is "directly connected" or "directly connected" to another element, it should be understood that the other element does not exist 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. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as “comprise” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It is to be understood that this does not preclude the possibility of the presence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in 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 the overall understanding, the same reference numerals are used for the same components in the drawings, and duplicate descriptions of the same components are omitted.

A communication network to which embodiments according to the present invention are applied will be described. A communication system includes 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). ) and so on. A 4G communication network and a 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 may support communication in a frequency band of 6 GHz or higher as well as a frequency band of 6 GHz or less. A 4G communication network can support communication in a frequency band of 6 GHz or less. The 5G communication network can support communication not only in frequency bands below 6 GHz, but also in frequency bands above 6 GHz. A communication network to which embodiments according to the present invention are applied is not limited to the content described below, and embodiments according to the present invention may be applied to various communication networks. Here, a communication network may be used in the same meaning as a communication system.

1 is a conceptual diagram illustrating a first embodiment of a non-terrestrial network.

Referring to FIG. 1 , the non-terrestrial network may include a satellite 110 , a communication node 120 , a gateway 130 , a data network 140 , and the like. The non-terrestrial network shown in FIG. 1 may be a transparent payload-based non-terrestrial network. The satellite 110 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 communication node 120 may include a communication node located on the ground (eg, user equipment (UE), a terminal) and a communication node located on a non-ground (eg, an airplane, a drone). A service link may be established between the satellite 110 and the communication node 120 , and the service link may be a radio link. Satellite 110 may provide communication services to communication node 120 using one or more beams. The shape of the footprint of the beam of the satellite 110 may be elliptical.

The communication node 120 may perform communication (eg, downlink communication, uplink communication) with the satellite 110 using LTE technology and/or NR technology. Communication between the satellite 110 and the communication node 120 may be performed using an NR-Uu interface. If dual connectivity (DC) is supported, the communication node 120 may be connected to the satellite 110 as well as other base stations (eg, base stations supporting LTE and/or NR functions), and may be connected to the LTE and/or NR functions. DC operation may be performed based on the technology defined in the standard.

The gateway 130 may be located on the ground, and a feeder link may be established between the satellite 110 and the gateway 130 . The feeder link may be a wireless link. The gateway 130 may be referred to as a “non-terrestrial network (NTN) gateway”. Communication between the satellite 110 and the gateway 130 may be performed based on an NR-Uu interface or a satellite radio interface (SRI). The gateway 130 may be connected to the data network 140 . A “core network” may exist between the gateway 130 and the data network 140 . In this case, the gateway 130 may be connected to the core network, and the core network may be connected to the data network 140 . The core network may 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 130 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 130 and the data network 140 . In this case, the gateway 130 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 140 . The base station and core network may support NR technology. Communication between the gateway 130 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) may be performed based on the NG-C/U interface. can

2 is a conceptual diagram illustrating a second embodiment of a non-terrestrial network.

Referring to FIG. 2 , the non-terrestrial network may include a satellite #1 211 , a satellite #2 212 , a communication node 220 , a gateway 230 , a data network 240 , and the like. The non-terrestrial network shown in FIG. 2 may be a non-terrestrial network based on a regenerative payload. For example, each of the satellites #1-2 (211, 212) is attached to a payload received from another entity (eg, communication node 220, gateway 230) constituting a non-terrestrial network. A regeneration operation (eg, a demodulation operation, a decryption operation, a re-encoding operation, a re-modulation operation, and/or a filtering operation) may be performed for the data, and the regenerated payload may be transmitted.

Each of satellites #1-2 (211, 212) may be an LEO satellite, a MEO satellite, a GEO satellite, a HEO satellite, or a UAS platform. The UAS platform may include HAPS. The satellite #1 (211) may be connected to the satellite #2 (212), and an inter-satellite link (ISL) may be established between the satellite #1 (211) and the satellite #2 (212). The ISL may operate at a radio frequency (RF) frequency or an optical band. ISL may be set as optional. The communication node 220 may include a communication node located on the ground (eg, a UE, a terminal) and a communication node located on a non-ground (eg, an airplane, a drone). A service link (eg, a radio link) may be established between satellite #1 211 and the communication node 220 . Satellite #1 211 may provide communication services to communication node 220 using one or more beams.

The communication node 220 may perform communication (eg, downlink communication, uplink communication) with satellite #1 211 using LTE technology and/or NR technology. Communication between satellite #1 211 and the communication node 220 may be performed using an NR-Uu interface. If DC is supported, the communication node 220 may be connected to satellite #1 (211) as well as other base stations (eg, base stations supporting LTE and/or NR functions) and conform to LTE and/or NR standards. DC operation may be performed based on the defined technology.

The gateway 230 may be located on the ground, a feeder link may be established between the satellite #1 211 and the gateway 230 , and a feeder link may be established between the satellite #2 212 and the gateway 230 . have. The feeder link may be a wireless link. When the ISL is not established between the satellite #1 (211) and the satellite #2 (212), a feeder link between the satellite #1 (211) and the gateway 230 may be mandatory.

Communication between each of the satellites #1-2 (211, 2122) and the gateway 230 may be performed based on an NR-Uu interface or SRI. The gateway 230 may be connected to the data network 240 . A “core network” may exist between the gateway 230 and the data network 240 . In this case, the gateway 230 may be connected to the core network, and the core network may be connected to the data network 240 . The core network may support NR technology. For example, the core network may include AMF, UPF, SMF, and the like. Communication between the gateway 230 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 230 and the data network 240 . In this case, the gateway 230 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 240 . The base station and core network may support NR technology. Communication between the gateway 230 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) may be performed based on the NG-C/U interface. can

Meanwhile, entities (eg, satellites, communication nodes, gateways, etc.) constituting the non-terrestrial network shown in FIGS. 1 and 2 may be configured as follows.

3 is a block diagram illustrating a first embodiment of entities constituting a non-terrestrial network.

Referring to FIG. 3 , the entity 300 may include at least one processor 310 , a memory 320 , and a transceiver 330 connected to a network to perform communication. Also, the entity 300 may further include an input interface device 340 , an output interface device 350 , a storage device 360 , and the like. Each component included in the entity 300 may be connected by a bus 370 to communicate with each other.

However, each of the components included in the entity 300 may not be connected to the common bus 370 but to the processor 310 through an individual interface or an individual bus. For example, the processor 310 may be connected to at least one of the memory 320 , the transceiver 330 , the input interface device 340 , the output interface device 350 , and the storage device 360 through a dedicated interface. .

The processor 310 may execute a program command stored in at least one of the memory 320 and the storage device 360 . The processor 310 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 320 and the storage device 360 may be configured as at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory 320 may be configured as at least one of a read only memory (ROM) and a random access memory (RAM).

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

When the satellite 110 in the non-terrestrial network shown in FIG. 1 is a GEO satellite (eg, a GEO satellite supporting a transparent function), this may be referred to as “scenario A”. In the non-terrestrial network shown in FIG. 2, when satellites #1-2 (211, 212) are GEO satellites (eg, GEO supporting regenerative function), this may be referred to as “scenario B”. have.

When the satellite 110 in the non-terrestrial network shown in FIG. 1 is an LEO satellite with steerable beams, it may be referred to as “scenario C1”. If the satellite 110 in the non-terrestrial network shown in FIG. 1 is an LEO satellite with beams move with satellite, this may be referred to as “scenario C2”. In the non-terrestrial network shown in FIG. 2 , when satellites #1-2 ( 211 , 212 ) are LEO satellites with steerable beams, this may be referred to as “scenario D1”. In the non-terrestrial network shown in FIG. 2 , when satellites #1-2 ( 211 , 212 ) are LEO satellites 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, a delay constraint may be defined as shown in Table 3 below.

Next, retransmission methods based on statistical information on the decoding result of data will be described. Even when a method (eg, transmission or reception of a signal) performed in a first communication node among communication nodes is described, a second communication node corresponding thereto is a method (eg, a method corresponding to the method performed in the first communication node) For example, reception or transmission of a signal) may be performed. That is, when the operation of the terminal is described, the corresponding base station may perform the operation corresponding to the operation of the terminal. Conversely, when the operation of the base station is described, the corresponding terminal may perform the operation corresponding to the operation of the base station.

A retransmission method (eg, a retransmission mechanism) may be designed assuming a specific range of round trip time (RTT), and the retransmission method may be dependent on the RTT. Therefore, when the RTT is changed, a new retransmission method may be required. Referring to the scenarios described in Table 3, RTT (eg, RTD) in a non-terrestrial network may be longer than RTT in an existing communication network (eg, LTE communication network, NR communication network). Therefore, for a non-terrestrial network, a new retransmission method tolerable to delay may be required instead of a retransmission method designed according to a relatively short RTT.

A blind retransmission method (eg, multiple retransmission method) may be used as a new retransmission method. In the blind retransmission method, data may be transmitted in the aggregated slot(s) according to the slot aggregation method, and the HARQ response to the corresponding data (eg, ACK (acknowledgement) or NACK (negative ACK)) is may not be transmitted. That is, the feedback operation of the HARQ response may be disabled. When the blind retransmission method is used, the HARQ response for data may not exist. In this case, since a transmitting node (eg, a base station or a terminal) cannot know a link state (eg, throughput), resources for retransmission of data may be wasted. The above-described slot aggregation method may be applied not only to a non-terrestrial network but also to other communication networks (eg, an LTE communication system, an NR communication system). In embodiments, a transmitting node may be a communication node transmitting data and a receiving node may be a communication node receiving data. For example, when the transmitting node is a base station, the receiving node may be a terminal. Alternatively, when the transmitting node is a terminal, the receiving node may be a base station or another terminal.

4 is a conceptual diagram illustrating a first embodiment of a blind retransmission method in a communication system.

Referring to FIG. 4 , the blind retransmission method may be performed based on the slot aggregation method, and the feedback operation of the HARQ response may not be performed. The transmitting node may repeatedly transmit the same transport block (TB) (eg, a TB composed of the same data unit) in the aggregated slots (eg, S slots). Here, S may be a natural number. The number of aggregated slots may be indicated by a slot aggregation factor (SAF). The repeated transmission operation of the same TB may be performed in units of SAF (eg, an aggregated transmission interval). In one aggregated transmission interval, the same TB may be transmitted more than once, and the same TB including different information may be transmitted for each slot.

That is, transmission information may be changed for each slot in one aggregated transmission interval. The transmission information may be information selected from a rate-matched circular buffer. Information selected from the circular buffer may be determined according to a redundancy version (RV). Based on the RV value applied to the supertransmission TB in the aggregated transmission interval and the transmission order of the current TB, the RV value applied to the current TB may be determined. The super-transmission TB may be a TB transmitted through the first slot in the aggregated transmission interval.

When the slot aggregation method is used, the HARQ response may be generated based on a result of decoding data performed by a receiving node (eg, a base station or a terminal). In this case, the HARQ response may include decoding results for each of all TBs received in the aggregated transmission interval. As another example, one HARQ response for all TBs received in the aggregated transmission interval may be generated instead of one TB. That is, the HARQ response may be generated in units of an aggregated transmission interval. One HARQ response may be generated by bundling decoding results for all TBs received in one aggregated transmission interval. For example, when the results of cyclic redundancy check (CRC) for all TBs received in one aggregated transmission interval are CRC failures, the receiving node may transmit a NACK to the transmitting node as a HARQ response. When the CRC result(s) for one or more TB(s) received in one aggregated transmission interval is CRC OK, the receiving node may transmit an ACK to the transmitting node in a HARQ response.

5 is a flowchart illustrating a first embodiment of a retransmission method in a communication system.

Referring to FIG. 5 , a communication system (eg, an LTE communication system, an NR communication system, and a non-terrestrial network) may include a transmitting node and a receiving node. The sending node may be a communication node transmitting data, and the receiving node may be a communication node receiving data. Each of the transmitting node and the receiving node may be configured the same as or similar to the communication node 300 illustrated in FIG. 3 .

The transmitting node may set transmission parameters (S501). The transmission parameter may include an effective code rate related parameter and/or a HARQ related parameter. The transmitting node may transmit the transmission parameters to the receiving node (S502). The transmission parameter may be transmitted through one or a combination of two or more of system information, a radio resource control (RRC) message, a medium access control (MAC) message, and a physical (PHY) message. The system information may be a master information block (MIB) and/or a system information block (SIB). The MAC message may be a message including a MAC control element (CE). The PHY message may be control information, and the control information may be downlink control information (DCI), uplink control information (UCI), and/or sidelink control information (SCI).

The receiving node may receive transmission parameters from the transmitting node. The transmitting node may transmit a transport block (TB) to the receiving node based on the transmission parameter (S503). Here, the transmission operation may be performed in units of TB. The receiving node may perform a receiving operation of the TB based on the transmission parameter. For example, the receiving node may generate a HARQ response (eg, ACK or NACK) based on the decoding result of the TB (S504). The receiving node may transmit a HARQ response to the transmitting node (S505).

The transmitting node may receive the HARQ response from the receiving node, and may determine whether the HARQ response is ACK or NACK (S506). If the HARQ response is ACK, the transmitting node may determine that the TB transmitted in step S503 has been successfully received by the receiving node, and may perform a transmission operation of a new TB (S507). Alternatively, when a new TB does not exist in the transmitting node, the transmission operation of the TB may be terminated.

On the other hand, when the HARQ response is NACK, the transmitting node may reset the transmission parameter by performing step S501 again, and may perform a TB retransmission operation based on the reset transmission parameter. That is, the transmitting node may perform a rate control operation on the retransmission TB based on the HARQ response (eg, NACK). The transmission parameter for the retransmission TB may be set differently from the transmission parameter for the supertransmission TB.

6 is a flowchart illustrating a second embodiment of a retransmission method in a communication system.

Referring to FIG. 6 , a communication system (eg, an LTE communication system, an NR communication system, and a non-terrestrial network) may include a transmitting node and a receiving node. Each of the transmitting node and the receiving node may be configured the same as or similar to the communication node 300 illustrated in FIG. 3 . The retransmission method shown in FIG. 6 may be performed based on the slot aggregation method. For example, the same TB (eg, a TB configured with the same data unit) may be repeatedly transmitted in an aggregated transmission interval (eg, slots indicated by SAF). TBs repeatedly transmitted in one aggregated transmission interval may have different RVs.

The transmitting node may set transmission parameters (S601). The transmission parameters may include effective code rate related parameters and/or HARQ related parameters. The transmitting node may transmit the transmission parameters to the receiving node (S602). The transmission parameter may be transmitted through one or a combination of two or more of system information, RRC message, MAC message, and PHY message. The receiving node may receive transmission parameters from the transmitting node. The transmission parameter may be set (eg, updated) according to the number of transmissions or receptions of the TB (S603). For example, the transmitting node may set the transmission parameter according to the number of TB transmissions in one aggregated transmission interval, and the receiving node may set the transmission parameter according to the number of TB receptions in one aggregated transmission interval.

The transmitting node may transmit the TB to the receiving node based on the transmission parameter (S604). The transmitting node may repeatedly transmit the TB as much as the SAF in the aggregated transmission interval. For example, the transmitting node may compare the number of TB transmissions and the SAF in the aggregated transmission interval (S606-1). If the number of transmissions of the TB in the aggregated transmission interval is less than the SAF, the transmitting node may reset the transmission parameter according to the number of transmissions of the TB (S603), and based on the reset transmission parameter, the TB may be transmitted to the receiving node ( S604).

On the other hand, when the number of transmissions of the TB in the aggregated transmission interval is equal to the SAF, the transmitting node may perform steps after step S606-1. For example, when the HARQ feedback operation is disabled, the transmitting node may perform a transmission operation of a new TB (S609). On the other hand, when the HARQ feedback operation is enabled (enabled), the transmitting node may receive a HARQ response from the receiving node, and may operate based on the received HARQ response.

Meanwhile, the reception node may perform a reception operation of the TB based on the transmission parameter. For example, the receiving node may generate a HARQ response (eg, ACK or NACK) based on the decoding result of the TB ( S605 ). Step S605 may be performed in units of TB. The receiving node may compare the number of TB receptions and the SAF in the aggregated transmission section (S606-2). If the number of receptions of the TB in the aggregated transmission interval is less than the SAF, the receiving node may reset the transmission parameter according to the number of receptions of the TB (S603), and may perform a reception operation of the TB based on the reset transmission parameter. . On the other hand, when the number of TB receptions in the aggregated transmission interval is equal to the SAF, the reception node may transmit HARQ responses for all TBs received in the aggregated transmission interval to the transmission node (S607). Step S607 may be performed when the HARQ feedback operation is enabled. When the HARQ feedback operation is disabled, the receiving node may perform a new TB reception operation without performing step S607.

The HARQ response transmitted in step S607 may include decoding results for each of all TBs received in the aggregated transmission interval. As another example, when decoding results for all TBs received in the aggregated transmission interval are failures, the HARQ response transmitted in step S607 may be NACK. As another example, when the decoding result for at least one TB received in the aggregated transmission interval is successful, the HARQ response transmitted in step S607 may be ACK.

The transmitting node may receive the HARQ response from the receiving node, and may determine whether the HARQ response is ACK or NACK (S608). When the HARQ response is ACK, the transmitting node may determine that the TB transmitted in step S604 has been successfully received by the receiving node, and may perform a transmission operation of a new TB in the next aggregated transmission interval (S609). Alternatively, when a new TB does not exist in the transmitting node, the transmission operation of the TB may be terminated.

On the other hand, when the HARQ response is NACK, the transmitting node may reset the transmission parameter by performing step S601 again, and may perform a retransmission operation of the TB based on the reset transmission parameter. That is, the transmitting node may perform a rate control operation on the retransmission TB based on the HARQ response (eg, NACK). The transmission parameter for the retransmission TB may be set differently from the transmission parameter for the supertransmission TB. The TB retransmission operation may be performed in a new aggregated transmission interval.

On the other hand, when the retransmission procedure is performed based on the slot aggregation method in the non-terrestrial network, the HARQ response may not be fed back. That is, in the embodiment shown in FIG. 6 , step S607 may not be performed. In this case, in order to guarantee reliability, the number of retransmissions of the TB may be preset. Since the HARQ response is not fed back, the HARQ response cannot be used to determine whether to retransmit the TB. Due to this constraint, the number of retransmissions of the TB may be preset before transmission of the TB, and the TB may be transmitted as many times as the preset number of retransmissions. In the retransmission procedure of the TB, the remaining transmission parameters in addition to some transmission parameters (eg, RV) may be equally applied to the supertransmission TB and the retransmission TB.

If there is no HARQ response, a transmission parameter corresponding to a current state (eg, a channel state, a reception state, etc.) may not be determined. For example, the transmission parameter may be set to satisfy a reliability higher than the reliability corresponding to the current state, and in this case, resources may be wasted. Alternatively, the transmission parameter may be set to satisfy a reliability lower than the reliability corresponding to the current state, and in this case, the transmission may fail.

When the slot aggregation method is used, one HARQ response may be generated by bundling decoding results for each of all TBs received in one aggregated transmission interval. One HARQ response may be ACK or NACK for one aggregated transmission period, and may not indicate ACK or NACK for each of TBs received in one aggregated transmission period. Accordingly, the transmitting node may not be able to check the number of ACKs generated in one aggregated transmission interval based on one HARQ response. In this case, the transmitting node cannot confirm whether the transmission parameter has "appropriate reliability corresponding to the current state", "reliability lower than the reliability corresponding to the current state", or "reliability higher than the reliability corresponding to the current state".

7 is a conceptual diagram illustrating a first embodiment of SAF required according to a data decoding result in a communication system.

Referring to FIG. 7 , SAF may be one of transmission parameters. SAF may indicate S, and S may be a natural number. In case 3, a smaller SAF than the SAF corresponding to the current state may be used, and accordingly, ACK may not occur in one aggregated transmission interval. Meanwhile, in case 2, an appropriate SAF corresponding to the current state may be used. In this case, one ACK may occur in one aggregated transmission interval. Finally, in case 1, a larger SAF than the SAF consistent with the current state may be used. In this case, two or more decoding successes may occur in one aggregated transmission interval. In this case, one HARQ response in one aggregated transmission interval may be determined as ACK, and accordingly, Case 2 may not be distinguished from Case 3 from the viewpoint of the transmitter. In one aggregated transmission interval, TB transmissions other than the TB transmission related to the first decoding success may be unnecessary. Resources (eg, radio resources) may be wasted due to unnecessary TB transmissions. However, since the HARQ response for one aggregated transmission interval indicates only the success or failure of the entire aggregated transmission interval with one HARQ response, and does not indicate the resources wasted by the current transmission, it is not easy to reduce the wasted resources. can

Meanwhile, in embodiments, the transmission parameter may include an effective code rate related parameter and/or an HARQ related parameter (eg, a retransmission related parameter). The effective code rate related parameter may include one or more parameters defined in Table 4 below, and the HARQ related parameter may include one or more parameters defined in Table 5 below.

In order to solve the above problem, the retransmission methods may be performed as follows.

1) Uplink transmission procedure

In the uplink transmission procedure, the decoding result and the HARQ response may be generated by a base station (eg, a receiver included in the base station), and transmission parameters may be set by the base station. Therefore, even when the HARQ operation (eg, the feedback operation of the HARQ response) is disabled in the uplink transmission procedure, the base station performs the HARQ response (eg, ACK) based on the decoding result for the uplink data received from the terminal. Alternatively, NACK) may be generated, and transmission parameters may be set using the decoding result.

When the transmission parameter is changed, the base station may inform the terminal of the changed transmission parameter. For example, the base station may transmit the changed transmission parameter to the terminal through one or a combination of two or more of system information, an RRC message, a MAC message, and a PHY message. To quickly transmit transmission parameters, MAC messages and/or PHY messages may be used. In this case, a specific transmission parameter (eg, SAF) may be transmitted through a MAC message and/or a PHY message.

2) Downlink transmission procedure

In the downlink transmission procedure, the decoding result and the HARQ response may be generated by the terminal (eg, a receiver included in the terminal), and transmission parameters may be set by the base station. If the HARQ response is not transmitted to the base station, the HARQ response may not be used to determine transmission parameters.

2-1) HARQ How to replace the response

When channel reciprocity is established, downlink performance (eg, downlink channel state) may be estimated based on uplink performance (eg, uplink channel state). Therefore, the base station can estimate the HARQ response to the downlink data (hereinafter referred to as "downlink HARQ response") based on the HARQ response to the uplink data (hereinafter referred to as "uplink HARQ response"). In this case, the base station may simply determine that the downlink HARQ response is the same as the uplink HARQ response. Alternatively, when the uplink metric is similar to the downlink metric, the base station may regard the uplink HARQ response as a downlink HARQ response.

If the uplink metric is not similar to the downlink metric, the base station may predict the downlink HARQ response using the uplink HARQ response. Here, the metric may be one or more of an effective code rate, spectral efficiency, and channel stat information (CSI) feedback information. In addition to the above-described information, other information may be used as a metric. Also, the above procedure may be applied by replacing the HARQ response with the decoding result.

2-2) A method of generating statistical information by statistically collecting decoding results and feeding back statistical information

The terminal may receive one or more TBs from the base station, may generate a decoding result for each of the one or more TBs, and may generate statistical information of the decoding results. The statistical information may include one or more of probability moment values such as mean, deviation, etc., minimum, maximum, average, and difference for M transmissions and/or time N. The probability moment value used as statistical information may be preset. When M or more samples (eg, TBs) have been received, statistical information may be generated. Alternatively, when samples corresponding to time N are obtained, statistical information may be generated.

For example, the base station may determine a value used as statistical information, and may inform the terminal of the determined value using one or a combination of two or more of system information, RRC message, MAC message, and PHY message. Alternatively, the terminal may determine a value used as statistical information, and may inform the base station of the determined value using one or a combination of two or more of an RRC message, a MAC message, and a PHY message.

M and N may be preset. M may be a natural number. N may be a rational number, and the unit of time may be μs (microsecond), ms (millisecond), or s (second). For example, the base station may determine M and/or N, and may inform the terminal of M and/or N using one or a combination of two or more of system information, RRC message, MAC message, and PHY message. Alternatively, the terminal may determine M and/or N, and may inform the base station of M and/or N using one or a combination of two or more of an RRC message, a MAC message, and a PHY message.

Statistical information on the decoding result may include one or more information elements defined in Table 6 below. The information element(s) used as statistical information may be preset. For example, the base station may determine the information element(s) used as statistical information, and use the determined information element(s) one or a combination of one or more of system information, RRC message, MAC message, and PHY message to the terminal can inform you Alternatively, the terminal may determine the information element(s) used as statistical information, and inform the base station of the determined information element(s) using one or a combination of two or more of an RRC message, a MAC message, and a PHY message.

(1) Feedback method of statistical information

The terminal may generate statistical information including one or more information elements defined in Table 6, and may transmit the statistical information to the base station through one or a combination of two or more of an RRC message, a MAC message, and a PHY message. The information element(s) included in the statistical information may be preset by the base station or the terminal. Statistical information may be transmitted from the terminal to the base station at a preset transmission time. The transmission time of the statistical information may be preset. For example, the base station may determine a transmission time of the statistical information, and may inform the terminal of the determined transmission time through one or a combination of two or more of system information, an RRC message, a MAC message, and a PHY message.

Alternatively, the terminal may determine the transmission time of the statistical information, and may inform the base station of the determined transmission time through one or a combination of two or more of system information, an RRC message, a MAC message, and a PHY message. In this case, the base station may reset the transmission parameters in consideration of the transmission time set by the terminal.

The terminal may transmit an information element necessary for setting the transmission parameter to the base station. In this case, the base station may determine whether to apply the information element received from the terminal. When it is necessary to apply the information element received from the terminal, the base station may determine the efficiency of the transmission parameter, and may change the transmission parameter according to the result of the determination of the efficiency.

(2) Feedback method of information indicating whether the transmission parameter is efficient

The terminal may generate statistical information on the decoding result. Thereafter, the terminal may determine the efficiency of the transmission parameter, and information indicating whether the transmission parameter is effective (hereinafter referred to as "efficiency information") is provided by one or more combinations of RRC messages, MAC messages, and PHY messages. can be transmitted to the base station through The base station may receive efficiency information from the terminal, and may reset transmission parameters in consideration of the efficiency information.

For example, the metric used to determine the efficiency of the transmission parameter may be statistical information (eg, the average number) of the number of decoding successes occurring in one or more aggregated transmission intervals. In this case, if the average of the number of successful decoding occurs in the aggregated transmission interval is greater than one, the terminal may determine that a change in the transmission parameter is necessary. That is, the terminal may determine that the transmission parameter is not efficient, and may transmit efficiency information indicating that the transmission parameter is not efficient to the base station. Here, it may be necessary to change the effective code rate in an increasing direction. For example, it may be necessary to change the aggregation factor in a decreasing direction among the effective code rate related parameters, and the corresponding information may be indicated by the efficiency information. Here, the conditions for determining that the transmission parameter needs to be changed may be variously changed to "the average of the number of successful decoding exceeds 1.5", "the average of the number of successful decoding is 2 or more", and the like.

When the average of the number of successful decoding occurs in the aggregated transmission interval is one, the terminal may determine that the transmission parameter is efficient, and may transmit efficiency information indicating that the transmission parameter is efficient to the base station. Alternatively, since there is no need to change the transmission parameter, the terminal may not perform a separate operation. Here, the condition for determining that the transmission parameter needs to be changed may be variously changed, such as "the average of the number of successful decoding exists between 0.5 and 1.5".

When the average of the number of successful decoding in the aggregated transmission interval is less than one, the terminal may determine that a change in the transmission parameter is necessary. That is, the terminal may determine that the transmission parameter is not efficient, and may transmit efficiency information indicating that the transmission parameter is not efficient to the base station. Here, among the transmission parameters, it may be necessary to change the effective code rate in a decreasing direction. For example, it may be necessary to change the aggregation factor in an increasing direction among the effective code rate related parameters, and the corresponding information may be indicated by efficiency information. Here, the conditions for determining that a change in the transmission parameter is necessary may be variously changed to “the average of the number of successful decoding is less than 0.5”, “when decoding success does not occur”, and the like.

The above-described embodiment may be performed for the aggregation factor as well as other parameters. In this case, the execution order or priority may be preset. For example, the base station may determine the execution order or priority of the generation/transmission operation of the efficiency information, and the determined execution order or the determined priority is a combination of one or more of system information, RRC message, MAC message, and PHY message can be notified to the terminal through Alternatively, the terminal may determine the execution order or priority of the generation/transmission operation of efficiency information, and inform the base station of the determined execution order or the determined priority through one or a combination of two or more of an RRC message, a MAC message, and a PHY message can

Meanwhile, the transmission time of the efficiency information may be preset. For example, the base station may determine a transmission time of the efficiency information, and may inform the terminal of the determined transmission time through one or a combination of two or more of system information, an RRC message, a MAC message, and a PHY message. Alternatively, the terminal may determine the transmission time of the efficiency information, and may inform the base station of the determined transmission time through one or a combination of two or more of an RRC message, a MAC message, and a PHY message.

In the feedback procedure of the efficiency information, information indicating that a change of the transmission parameter is required, a changed transmission parameter (eg, a changed effective code rate), a transmission parameter requiring a change, and a difference between the current transmission parameter and the target transmission parameter ( For example, one or more of the difference between the current effective code rate and the target effective code rate) may be fed back together with the efficiency information. Alternatively, information indicating up, down, or maintenance of a transmission parameter may be transmitted.

The terminal may transmit information indicating whether a change of the transmission parameter is necessary to the base station. The base station may determine whether to apply the information received from the terminal, and may change the transmission parameter when the information needs to be applied.

A comparison criterion (eg, a metric) used to determine the efficiency of a transmission parameter may be a target error rate, throughput, latency, and/or a transmission parameter. A value of a metric used to determine the efficiency of a transmission parameter may be calculated based on a quality of service (QoS) condition. A value of a metric used to determine the efficiency of a transmission parameter may be indicated by a higher layer. The value of the metric used to determine the efficiency of the transmission parameter may be preset. For example, the base station may determine the value of the metric used to determine the efficiency of the transmission parameter, and inform the terminal of the determined value through one or a combination of two or more of system information, RRC message, MAC message, and PHY message. can Alternatively, the terminal may determine a value of a metric used to determine the efficiency of the transmission parameter, and inform the base station of the determined value through one or a combination of two or more of an RRC message, a MAC message, and a PHY message.

(3) Feedback method of guide information for changing transmission parameters

The terminal may generate statistical information on the decoding result, and may transmit efficiency information to the base station. In addition, the terminal may reset the transmission parameter, and transmit the reset transmission parameter (or guide information on the reset transmission parameter) to the base station through one or a combination of two or more of an RRC message, a MAC message, and a PHY message. have. The transmission time of the reset transmission parameter (or guide information on the reset transmission parameter) may be preset. The base station may determine the transmission time of the reset transmission parameter (or guide information for the reset transmission parameter), and the determined transmission time through one or a combination of two or more of system information, RRC message, MAC message, and PHY message You can inform the terminal. Alternatively, the terminal may determine the transmission time of the reset transmission parameter (or guide information for the reset transmission parameter), and the determined transmission time is an RRC message, a MAC message, and a PHY message through one or two or more combinations of the base station can inform you

The guide information for changing the transmission parameter may be used as a guideline for determining the to-be-changed transmission parameter and/or the to-be-changed value of the transmission parameter. The transmission parameter transmitted as guide information for changing the transmission parameter may be preset. The base station may determine a transmission parameter used as guide information for changing the transmission parameter, and inform the terminal of the determined transmission parameter through one or a combination of two or more of system information, an RRC message, a MAC message, and a PHY message. Alternatively, the terminal may determine a transmission parameter used as guide information for changing the transmission parameter, and inform the base station of the determined transmission parameter through one or a combination of two or more of an RRC message, a MAC message, and a PHY message.

In the guide information feedback procedure, at least one of information indicating that a change of the transmission parameter is required, a changed transmission parameter, a transmission parameter requiring change, and a difference between the current transmission parameter and the target transmission parameter may be fed back together with the guide information have. Alternatively, information indicating up, down, or maintenance of a transmission parameter may be transmitted.

The terminal may transmit guide information for changing the transmission parameter to the base station. The base station may determine whether to apply the guide information received from the terminal, and when it is necessary to apply the guide information, the base station may change the transmission parameter based on the guide information.

For example, the metric used to determine whether the guide information of the transmission parameter is fed back may be statistical information (eg, the average number) of the number of decoding successes occurring in one or more aggregated transmission sections. In this case, if the average of the number of successful decoding occurs in the aggregated transmission interval is more than one, the terminal may determine that a change in the transmission parameter is necessary, and may transmit guide information of the transmission parameter to the base station. Here, the guide information may suggest an increase in the effective code rate. For example, the guide information may suggest a reduction of the aggregation factor among the effective code rate related parameters. However, when the aggregation factor is already set to the minimum value, the guide information may suggest a change of another parameter among the effective code rate related parameters. Here, the conditions for determining that the transmission parameter needs to be changed may be variously changed to "the average of the number of successful decoding exceeds 1.5", "the average of the number of successful decoding is 2 or more", and the like.

When the average of the number of successful decoding occurs in the aggregated transmission interval is one, the terminal may determine that there is no need to change the transmission parameter, and may not transmit the guide information to the base station. That is, the terminal may not perform a separate operation. Here, the condition for determining that the transmission parameter needs to be changed may be variously changed, such as "the average of the number of successful decoding exists between 0.5 and 1.5".

If the average of the number of successful decoding in the aggregated transmission interval is less than one, the terminal may determine that it is necessary to change the transmission parameter, and may transmit guide information of the transmission parameter to the base station. Here, the guide information may suggest a reduction in the effective code rate. For example, the guide information may suggest an increase in the aggregation factor among the effective code rate related parameters. However, when the aggregation factor is already set to the maximum value, the guide information may suggest a change of another parameter among the effective code rate related parameters. Here, the conditions for determining that a change in the transmission parameter is necessary may be variously changed to “the average of the number of successful decoding is less than 0.5”, “when decoding success does not occur”, and the like.

The above-described embodiment may be performed for the aggregation factor as well as other parameters. In this case, the execution order or priority may be preset. For example, the base station may determine the execution order or priority of the generation / transmission operation of the guide information, and the determined execution order or the determined priority system information, RRC message, MAC message, and a combination of one or more of PHY message can be notified to the terminal through Alternatively, the terminal may determine the execution order or priority of the generation/transmission operation of the guide information, and inform the base station of the determined execution order or the determined priority through one or a combination of two or more of an RRC message, a MAC message, and a PHY message can

8 is a flowchart illustrating a third embodiment of a retransmission method in a communication system.

Referring to FIG. 8 , a communication system (eg, an LTE communication system, an NR communication system, a non-terrestrial network) may include a transmitting node and a receiving node. Each of the transmitting node and the receiving node may be configured the same as or similar to the communication node 300 illustrated in FIG. 3 . The retransmission method shown in FIG. 8 may be performed based on the slot aggregation method. For example, the same TB may be repeatedly transmitted in an aggregated transmission interval (eg, slots indicated by SAF). TBs repeatedly transmitted in one aggregated transmission interval may have different RVs.

The transmitting node may set transmission parameters (S801). The transmission parameters may include effective code rate related parameters and/or HARQ related parameters. The transmitting node may transmit the transmission parameters to the receiving node (S802). The transmission parameter may be transmitted through one or a combination of two or more of system information, RRC message, MAC message, and PHY message. The receiving node may receive transmission parameters from the transmitting node. The transmission parameter may be set (eg, updated) according to the number of transmissions or receptions of the TB (S803). For example, the transmitting node may set the transmission parameter according to the number of TB transmissions in one aggregated transmission interval, and the receiving node may set the transmission parameter according to the number of TB receptions in one aggregated transmission interval.

The transmitting node may transmit the TB to the receiving node based on the transmission parameter (S804). The transmitting node may repeatedly transmit the TB as much as the SAF in the aggregated transmission interval. For example, the transmitting node may compare the number of TB transmissions and the SAF in the aggregated transmission section (S809-1). If the number of transmissions of the TB in the aggregated transmission interval is less than the SAF, the transmitting node may reset the transmission parameter according to the number of transmissions of the TB (S803), and based on the reset transmission parameter, the TB may be transmitted to the receiving node ( S804). On the other hand, when the number of transmissions of the TB in the aggregated transmission interval is equal to the SAF, the transmitting node may end the transmission operation in the aggregated transmission interval, and the transmission operation in the new aggregated transmission interval (eg, for a new TB) transmission operation) may be performed (S810). A transmission operation in the new aggregated transmission interval may be performed based on steps S801, S802, S803, S804, and S809-1.

Meanwhile, the reception node may perform a reception operation of the TB based on the transmission parameter. For example, the receiving node may generate a decoding result of the TB ( S805 ). Step S805 may be performed in units of TB or slots. The receiving node may generate statistical information, efficiency information, and/or guide information on the decoding result (S806). Statistical information, efficiency information, and/or guide information may be generated based on the method described above. The receiving node may determine whether a feedback condition of the information generated in step S806 (eg, statistical information, efficiency information, and/or guide information) is satisfied (S807).

For example, the feedback condition may be a transmission time. In this case, the receiving node may determine that the feedback condition is satisfied when a preset transmission time is reached, and may transmit statistical information, efficiency information, and/or guide information to the transmitting node at the preset transmission time ( S808). The information generated in step S806 may be transmitted through one or a combination of two or more of an RRC message, a MAC message, and a PHY message. As another example, the feedback condition may be a need to reset transmission parameters. In this case, the receiving node may determine that it is necessary to reset the transmission parameter based on the decoding result generated in step S805 and/or the information generated in step S806, and in this case, statistical information, efficiency information, and/or guide The information may be transmitted to the transmitting node (S808).

If the feedback condition is not satisfied, statistical information, efficiency information, and/or guide information may not be transmitted. For example, when the feedback condition is not satisfied in one aggregated transmission period, statistical information, efficiency information, and/or guide information may not be transmitted before the end of one aggregated transmission period. Alternatively, statistical information, efficiency information, and/or guide information may be transmitted regardless of feedback conditions. If steps S806 to S808 are performed after step S805, the entire communication procedure can be performed without problems. The timing of performing steps S806 to S808 may not be limited to the embodiment shown in FIG. 8 .

The transmitting node may receive statistical information, efficiency information, and/or guide information from the receiving node, and may reset transmission parameters in consideration of the statistical information, efficiency information, and/or guide information. The reset transmission parameters may be transmitted to the receiving node. If statistical information, efficiency information, and/or guide information are received from the receiving node before the end of the aggregated transmission interval #n, the transmitting node transmits the aggregated transmission interval #n with statistical information, efficiency information, and/or guide information. It may not be applied to the transmission operation for

That is, the transmitting node transmits statistical information, efficiency information, and/or guide information received in the aggregated transmission interval #n to a new aggregated transmission interval (eg, aggregated transmission interval #n) after the aggregated transmission interval #n. It can be applied to the transmission operation for +k). A transmission parameter for the aggregated transmission period #n+k may be set in consideration of statistical information, efficiency information, and/or guide information received in the aggregated transmission period #n. Here, each of n and k may be a natural number. Alternatively, the transmitting node may reset the transmission parameters for the aggregated transmission interval #n in consideration of statistical information, efficiency information, and/or guide information received in the aggregated transmission interval #n, and use the reset transmission parameter Thus, a transmission operation can be performed in the aggregated transmission interval #n. The reset transmission parameters may be transmitted to the receiving node.

Meanwhile, after performing step S807 or S808, the receiving node may compare the number of TB receptions and SAF in the aggregated transmission section (S809-2). If the number of TB receptions in the aggregated transmission interval is less than the SAF, the receiving node may reset the transmission parameters according to the number of receptions of the TBs (S803), and may perform a TB reception operation based on the reset transmission parameters. . On the other hand, if the number of TB transmissions in the aggregated transmission interval is equal to the SAF, the receiving node may end the reception operation in the aggregated transmission interval, and the reception operation in the new aggregated transmission interval (eg, reception of a new TB) operation) can be performed (S810). A reception operation in the new aggregated transmission interval may be performed based on steps S802 to S809-2.

9 is a flowchart illustrating a fourth embodiment of a retransmission method in a communication system.

Referring to FIG. 9 , a communication system (eg, an LTE communication system, an NR communication system, and a non-terrestrial network) may include a transmitting node and a receiving node. Each of the transmitting node and the receiving node may be configured the same as or similar to the communication node 300 illustrated in FIG. 3 . The retransmission method shown in FIG. 9 may be performed based on the slot aggregation method. For example, the same TB may be repeatedly transmitted in an aggregated transmission interval (eg, slots indicated by SAF). TBs repeatedly transmitted in one aggregated transmission interval may have different RVs.

Steps S901 to S909-2 illustrated in FIG. 9 may be performed in the same manner as steps S801 to S809-2 illustrated in FIG. 8 . The embodiment shown in FIG. 9 may further include "transmitting and receiving HARQ responses for all TBs received in the aggregated transmission interval" compared to the embodiment shown in FIG. 8 .

For example, the receiving node may compare the number of TB receptions and the SAF in the aggregated transmission interval. When the number of TBs received in the aggregated transmission interval is equal to the SAF, the reception node may transmit HARQ responses for all TBs received in the aggregated reception interval to the transmission node (S910).

The HARQ response transmitted in step S910 may include decoding results for each of all TBs received in the aggregated transmission interval. As another example, when decoding results for all TBs received in the aggregated transmission interval are CRC failures, the HARQ response transmitted in step S910 may be NACK. As another example, when the decoding result of at least one TB received in the aggregated transmission interval is CRC OK, the HARQ response transmitted in step S910 may be ACK.

The transmitting node may receive the HARQ response from the receiving node, and may determine whether the HARQ response is ACK or NACK (S911). When the HARQ response is ACK, the transmitting node may determine that the TB transmitted in step S904 is successfully received by the receiving node, and may perform a transmission operation of a new TB in the next aggregated transmission interval (S912). Alternatively, when a new TB does not exist in the transmitting node, the transmission operation of the TB may be terminated. On the other hand, when the HARQ response is NACK, the transmitting node may reset the transmission parameter by performing step S901 again, and may perform a TB retransmission operation based on the reset transmission parameter. The receiving node that has transmitted the ACK in step S910 may perform a reception operation of a new TB in the next aggregated transmission section (S912).

On the other hand, if steps S906 to S908 are performed after step S905, the entire communication procedure can be performed without problems. The timing of performing steps S906 to S908 may not be limited to the embodiment shown in FIG. 9 .

10 is a flowchart illustrating a fifth embodiment of a retransmission method in a communication system.

Referring to FIG. 10 , a communication system (eg, an LTE communication system, an NR communication system, and a non-terrestrial network) may include a transmitting node and a receiving node. Each of the transmitting node and the receiving node may be configured the same as or similar to the communication node 300 illustrated in FIG. 3 .

The retransmission method shown in FIG. 10 may be a general retransmission method rather than a blind retransmission method. That is, in the embodiment shown in FIG. 10 , the slot aggregation method may not be used. Steps S1001 to S1004 shown in FIG. 10 may be performed in the same manner as steps S501 to S504 shown in FIG. 5 . The embodiment shown in FIG. 10 may further include steps S1005 to S1007 compared to the embodiment shown in FIG. 5 . Steps S1005 to S1007 shown in FIG. 10 may be performed in the same manner as steps S806 to S808 shown in FIG. 8 .

On the other hand, after performing step S1006 or step S1007, the receiving node may transmit a HARQ response (eg, ACK or NACK) for the TB to the transmitting node (S1008). Since the HARQ response for the TB is transmitted in the embodiment shown in FIG. 10, steps S1005 to S1007 may be omitted. In this case, step S1008 may be performed after step S1004.

The transmitting node may receive the HARQ response from the receiving node, and may determine whether the HARQ response is ACK or NACK (S1009). When the HARQ response is ACK, the transmitting node may determine that the TB transmitted in step S1003 has been successfully received by the receiving node, and may perform a transmission operation of a new TB (S1010). A transmission parameter for a new TB may be set in consideration of statistical information, efficiency information, and/or guide information received from a receiving node. Alternatively, when a new TB does not exist in the transmitting node, the transmission operation of the TB may be terminated.

On the other hand, when the HARQ response is NACK, the transmitting node may reset the transmission parameter by performing step S1001 again, and may perform a TB retransmission operation based on the reset transmission parameter. Here, the transmission parameters for retransmission of the TB may be reset in consideration of statistical information, efficiency information, and/or guide information received from the receiving node.

On the other hand, if steps S1005 to S1007 are performed after step S1004, the entire communication procedure can be performed without problems. The timing of performing steps S1005 to S1007 may not be limited to the embodiment shown in FIG. 10 . For example, if steps S1005 to S1007 are performed only before the end of the TB, the entire communication procedure can be performed without problems.

Meanwhile, in the above-described retransmission methods (eg, the retransmission methods shown in FIGS. 5, 6, 8, 9, and/or 10), enable or disable the HARQ feedback operation ( disable) may be set as a separate transmission parameter. In this case, the retransmission method may be performed according to enabling or disabling of the HARQ feedback operation.

The HARQ feedback operation may be partially enabled or disabled by a specific granularity (eg, logical channel identifier (LCID), HARQ processor). In this case, a separate transmission parameter may be set for each “granularity”, “a subset of granularity”, or “group of granularity”, and a retransmission method may be managed. . When the HARQ feedback operation is partially enabled or disabled, a HARQ response according to the enabled HARQ feedback operation may be applied to the disabled HARQ feedback operation.

The methods according to the present invention may be implemented in the form of program instructions that can be executed by various computer means and recorded 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 available to those skilled in the art of computer software.

Examples of computer-readable media include hardware devices specially configured to store and carry out program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine language codes such as those generated by a compiler, but also high-level language codes that can be executed by a computer using an interpreter or the like. The hardware device described above may be configured to operate as at least one software module to perform the operations of the present invention, and vice versa.

Although it has been described with reference to the above embodiments, it will be understood by those skilled in the art that various modifications and changes can be made to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. will be able

Claims (18)

A method of operating a first communication node in a communication system, comprising:
receiving a plurality of transport block (TB) transmissions from a second communication node based on a transmission parameter in an aggregated transmission interval #n;
generating decoding results for the plurality of TB transmissions;
generating information necessary for changing the transmission parameter based on the decoding results; and
transmitting the necessary information to the second communication node;
The necessary information includes statistical information on the decoding results, and the statistical information is used to determine an effective code rate applied to an aggregated transmission interval #n+k after the aggregated transmission interval #n, and the wherein each of n and k is a natural number. The method according to claim 1,
The method of operation of the first communication node,
receiving the changed transmission parameter in consideration of the necessary information from the second communication node; and
Receiving one or more TB transmissions from the second communication node based on the changed transmission parameter in the aggregated transmission interval #n+k,
A method of operation of the first communication node. The method according to claim 1,
The method of operation of the first communication node,
When the number of the plurality of TB transmissions is the same as the number of the plurality of slots included in the aggregated transmission period #n, at a time point designated by the second communication node, the HARQ response for all of the plurality of TB transmissions and transmitting to the second communication node. The method according to claim 1,
wherein the necessary information is transmitted to the second communication node when a feedback condition is satisfied. The method according to claim 1,
Operation of the first communication node, wherein the aggregated transmission interval #n includes a plurality of slots, and the plurality of TB transmissions received in the aggregated transmission interval #n are generated based on the same data unit Way. The method according to claim 1,
The method of operation of the first communication node, wherein the statistical information indicates the number of decoding successes or decoding failures occurring in a plurality of aggregated transmission intervals. The method according to claim 1,
The method of operating a first communication node, wherein the necessary information further includes information indicating that the transmission parameter is not efficient. The method according to claim 1,
The method of operating the first communication node, wherein the necessary information further comprises a guideline for changing the transmission parameter. A method of operating a second communication node in a communication system, comprising:
transmitting the transmission parameters to the first communication node;
transmitting a plurality of transport block (TB) transmissions to the first communication node based on the transmission parameter in an aggregated transmission interval #n;
receiving information necessary for changing the transmission parameter from the first communication node;
changing the transmission parameter in consideration of the necessary information; and
transmitting the changed transmission parameters to the first communication node,
The necessary information includes statistical information on decoding results in the aggregated transmission interval #n, and the statistical information is an effective code rate applied to the aggregated transmission interval #n+k after the aggregated transmission interval #n. , wherein each of n and k is a natural number. 10. The method of claim 9,
The method of operation of the second communication node,
Transmitting one or more TB transmissions to the first communication node based on the changed transmission parameter in the aggregated transmission interval #n+k,
A method of operation of the second communication node. 10. The method of claim 9,
wherein the necessary information is received from the first communication node when a feedback condition is satisfied. 10. The method of claim 9,
Operation of a second communication node, wherein the aggregated transmission interval #n includes a plurality of slots, and the plurality of TB transmissions transmitted in the aggregated transmission interval #n are generated based on the same data unit Way. 10. The method of claim 9,
The method of operating a second communication node, wherein the statistical information indicates the number of decoding successes or decoding failures occurring in a plurality of aggregated transmission intervals. 10. The method of claim 9,
The method of operating a second communication node, wherein the necessary information further includes information indicating that the transmission parameter is not efficient or a guideline for changing the transmission parameter. delete delete delete delete

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