KR20210055585A - Method and apparatus for retransmission in communication system - Google Patents

Abstract

A method for retransmission in a communication network and a device thereof are disclosed. An operation method of a first communication node comprises the following steps of: receiving one or more TBs from a second communication node based on a transmission parameter in an aggregated transmission interval, which is #n; generating decoding results for the 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. Therefore, the method can guarantee reliability in a retransmission procedure and prevent resource waste.

Description

Method and apparatus for retransmission in communication network {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 the processing of rapidly increasing radio data, a frequency band higher than the frequency band of LTE (long term evolution) (or LTE-A) (for example, a frequency band of 6 GHz or less) (for example, 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 less, but also a frequency band of 6 GHz or more, 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 planes, drones, and satellites located not only on the ground but also on non-terrestrial is increasing, and for this purpose, a non-terrestrial network (NTN) The techniques for) are being discussed. The non-terrestrial network can 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 (e.g., user equipment (UE)) or a communication node located on a non-ground (e.g., airplane, drone) is not applicable to NR technology. It can be done on the basis of. 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 method. In this case, a hybrid automatic repeat request (HARQ) response (eg, acknowledgment (ACK) or negative ACK (NACK)) for data may not be transmitted. Since the transmitting node (eg, the base station or the terminal) that has transmitted the data cannot receive the HARQ response for the corresponding data, it may not be able to accurately check the state of the link (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 retransmission method and apparatus 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 receiving one or more TBs from a second communication node based on a transmission parameter in an aggregated transmission period #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 method of operating the first communication node includes receiving a transmission parameter changed in consideration of the necessary information from the second communication node, and one based on the changed transmission parameter in an aggregated transmission period #n+k. The step of receiving the above TBs from the second communication node may be further included, and k may be a natural number.

Here, in the operation method of 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 period #n, the one It may further include transmitting an 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 period #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.

In order to achieve the above object, a method of operating a second communication node according to a second embodiment of the present invention includes transmitting a transmission parameter to a first communication node, one based on the transmission parameter in an aggregated transmission period #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 the 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, where 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 the aggregated transmission period #n+k, and the k Can 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, a method of operating a first communication node according to a third embodiment of the present invention includes 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, and in 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 method of operating the first communication node comprises: receiving a transmission parameter changed in consideration of the necessary information from the second communication node, and receiving a second TB from the second communication node based on the changed transmission parameter. It may further include receiving, and 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 (e.g., a base station or a terminal) transmits statistical information about a result of decoding data, efficiency information of a transmission parameter, and/or guide information of a transmission parameter. Base station). The transmitting node may reset the transmission parameter 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 can be improved.

1 is a conceptual diagram showing a first embodiment of a non-terrestrial network.
2 is a conceptual diagram showing a second embodiment of a non-terrestrial network.
3 is a block diagram showing a first embodiment of an entity 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 flow chart showing 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 a SAF required according to a result of decoding data in a communication system.
8 is a flow chart showing a third embodiment of a retransmission method in a communication system.
9 is a flowchart showing a fourth embodiment of a retransmission method in a communication system.
10 is a flowchart showing a fifth embodiment of a retransmission method in a communication system.

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 should 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 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 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. It 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 this 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 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). ), etc. 4G communication networks and 5G communication networks can be classified as terrestrial networks.

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 a frequency band of 6 GHz or higher as well as a frequency band of 6 GHz or less. 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 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 non-terrestrial network based on a transparent payload. 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 (eg, a user equipment (UE), a terminal) located on the ground and a communication node (eg, an airplane, a drone) located on a non-ground basis. 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 an elliptical shape.

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 the NR-Uu interface. When DC (dual connectivity) is supported, the communication node 120 may be connected to the satellite 110 as well as 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 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 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 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 can 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) is performed based on the NG-C/U interface. I can.

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

Referring to FIG. 2, the non-terrestrial network may include satellite #1 211, satellite #2 212, communication node 220, gateway 230, 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 satellites #1-2 (211, 212) is in the payload received from another entity (for example, communication node 220, gateway 230) 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 (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. Satellite #1 (211) may be connected to satellite #2 (212), and an inter-satellite link (ISL) may be established between satellite #1 (211) and satellite #2 (212). The ISL can operate in 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 the satellite #1 211 and the communication node 220. Satellite #1 211 may provide a communication service to the 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 the satellite #1 211 and the communication node 220 may be performed using the NR-Uu interface. When DC is supported, the communication node 220 may be connected to satellite #1 211 as well as other base stations (eg, a base station supporting LTE and/or NR functions), and comply with 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 set between the satellite #1 (211) and the satellite #2 (212), the feeder link between the satellite #1 (211) and the gateway 230 may be set mandatory.

Communication between each of the satellites #1-2 (211, 2122) and the gateway 230 may be performed based on the 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 can 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 can 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) is performed based on the NG-C/U interface. I 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 showing a first embodiment of an entity constituting a non-terrestrial network.

Referring to FIG. 3, the entity 300 may include at least one processor 310, a memory 320, and a transmission/reception device 330 connected to a network to perform communication. In addition, the entity 300 may further include an input interface device 340, an output interface device 350, and a storage device 360. Each of the components 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 be connected through an individual interface or an individual bus based on the processor 310 instead of the common bus 370. 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 in which methods according to embodiments of the present invention are performed. Each of the memory 320 and the storage device 360 may be configured with at least one of a volatile storage medium and a nonvolatile storage medium. For example, the memory 320 may be composed of at least one of read only memory (ROM) and random access memory (RAM).

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

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

In the case where the satellite 110 in the non-terrestrial network shown in FIG. 1 is an LEO satellite having steerable beams, this may be referred to as “scenario C1”. In the case where the satellite 110 in the non-terrestrial network shown in FIG. 1 is an LEO satellite having beams move with satellite, it may be referred to as “scenario C2”. In the case where satellite #1-2 (211, 212) in the non-terrestrial network shown in FIG. 2 is an LEO satellite having adjustable beams, it may be referred to as “scenario D1”. In the case where satellite #1-2 (211, 212) in the non-terrestrial network shown in FIG. 2 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.

Next, retransmission methods based on statistical information on a result of decoding data 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 the operation corresponding to the operation of the terminal. Conversely, when the operation of the base station is described, a terminal corresponding thereto may perform an operation corresponding to the operation of the base station.

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

As a new retransmission method, a blind retransmission method (eg, a multiple retransmission method) may be used. In the blind retransmission method, data may be transmitted in the slot(s) aggregated according to the slot aggregation method, and the HARQ response (eg, acknowledgment (ACK) or negative ACK (NACK)) for the corresponding data is May not be transmitted. That is, the feedback operation of the HARQ response may be disabled. When the blind retransmission method is used, there may not be an HARQ response for data. In this case, since the transmitting node (eg, the base station or the terminal) cannot know the state of the link (eg, throughput), resources for data retransmission may be wasted. The above-described slot aggregation method can 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, the transmitting node may be a communication node that transmits data, and the receiving node may be a communication node that receives 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 a slot aggregation method, and a feedback operation of an 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 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 repetitive transmission operation of the same TB may be performed in units of SAF (eg, aggregated transmission interval). In one aggregated transmission period, the same TB may be transmitted more than once, and the same TB including different information may be transmitted for each slot.

That is, the transmission information may be changed for each slot in one aggregated transmission period. 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). In the aggregated transmission interval, the value of the RV applied to the current TB may be determined based on the value of the RV applied to the initial transmission TB and the transmission order of the current TB. The initial transmission TB may be a TB transmitted through the first slot in the aggregated transmission period.

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 period. As another example, instead of one TB, one HARQ response may be generated for all TBs received in the aggregated transmission period. That is, the HARQ response may be generated in units of aggregated transmission intervals. One HARQ response may be generated by bundling decoding results for all TBs received in one aggregated transmission period. For example, when CRC (cyclic redundancy check) results for all TBs received in one aggregated transmission period are CRC failure, 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 period is CRC OK, the receiving node may transmit an ACK to the transmitting node in the HARQ response.

5 is a flow chart showing 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, a non-terrestrial network) may include a transmitting node and a receiving node. The transmitting node may be a communication node that transmits data, and the receiving node may be a communication node that receives data. Each of the transmitting node and the receiving node may be configured in the same or similar to the communication node 300 shown in FIG. 3.

The transmitting node may set a transmission parameter (S501). The transmission parameter may include an effective code rate related parameter and/or an HARQ related parameter. The transmitting node may transmit the transmission parameter to the receiving node (S502). The transmission parameter may be transmitted through one or a combination of two or more of system information, radio resource control (RRC) message, medium access control (MAC) message, and 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 CE (control element). 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 the TB receiving operation based on the transmission parameter. For example, the receiving node may generate a HARQ response (eg, ACK or NACK) based on a result of decoding the TB (S504). The receiving node may transmit the HARQ response to the transmitting node (S505).

The transmitting node may receive the HARQ response from the receiving node, and may check whether the HARQ response is ACK or NACK (S506). When 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, if the 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 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 initial transmission 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 in the same or similar to the communication node 300 shown in FIG. 3. The retransmission method shown in FIG. 6 may be performed based on a slot aggregation method. For example, the same TB (eg, a TB composed of the same data unit) may be repeatedly transmitted in an aggregated transmission period (eg, slots indicated by the SAF). TBs repeatedly transmitted in one aggregated transmission period may have different RVs.

The transmitting node may set a transmission parameter (S601). The transmission parameter may include a parameter related to an effective code rate and/or a parameter related to HARQ. The transmitting node may transmit the transmission parameter 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 transmissions of TBs in one aggregated transmission interval, and the receiving node may set the transmission parameter according to the number of receptions of TBs 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 TB as much as SAF in the aggregated transmission period. For example, the transmitting node may compare the number of transmissions of the TB and the SAF in the aggregated transmission period (S606-1). When the number of TB transmissions in the aggregated transmission period is less than the SAF, the transmitting node may reset the transmission parameter according to the number of transmissions of the TB (S603), and transmit the TB to the receiving node based on the reset transmission parameter ( S604).

On the other hand, when the number of TB transmissions in the aggregated transmission period is the same as the SAF, the transmitting node may perform the 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, the transmitting node may receive a HARQ response from the receiving node and may operate based on the received HARQ response.

Meanwhile, the receiving node may perform a TB receiving operation 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 receptions of the TB and the SAF in the aggregated transmission period (S606-2). When the number of TB receptions in the aggregated transmission period 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 TB reception operation based on the reset transmission parameter. . On the other hand, when the number of TB receptions in the aggregated transmission interval is the same as the SAF, the receiving node may transmit HARQ responses for all TBs received in the aggregated transmission interval to the transmitting 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 reception operation of a new TB 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 period. As another example, if the decoding results for all TBs received in the aggregated transmission period are failure, 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 period 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 check whether the HARQ response is ACK or NACK (S608). If 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 period (S609). Alternatively, if the 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 initial transmission TB. The TB retransmission operation may be performed in a new aggregated transmission period.

Meanwhile, when a retransmission procedure is performed based on a slot aggregation scheme in a non-terrestrial network, the HARQ response may not be fed back. That is, step S607 may not be performed in the embodiment shown in FIG. 6. 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 limitation, 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 retransmission number. In the TB retransmission procedure, other transmission parameters in addition to some transmission parameters (eg, RV) may be equally applied to the initial transmission TB and the retransmission TB.

If there is no HARQ response, transmission parameters corresponding to the current state (eg, channel state, 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 scheme is used, one HARQ response may be generated by bundling decoding results for each of all TBs received in one aggregated transmission period. One HARQ response may be ACK or NACK for the entire aggregated transmission interval, and may not indicate ACK or NACK for each of the TBs received in one aggregated transmission interval. 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 "higher reliability than the reliability corresponding to the current state".

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

Referring to FIG. 7, SAF may be one of transmission parameters. SAF can indicate S, and S can be a natural number. In case 3, an SAF smaller than the SAF corresponding to the current state may be used, and accordingly, ACK may not occur in one aggregated transmission period. 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 period. Finally, in Case 1, a SAF larger than the SAF corresponding to the current state may be used. In this case, two or more decoding successes may occur in one aggregated transmission period. In this case, one HARQ response in one aggregated transmission period may be determined as ACK, and accordingly, case 2 may not be distinguished from case 3 from the perspective of the transmitting end. TB transmissions other than TB transmission related to the first decoding success in one aggregated transmission interval 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 of the current aggregated transmission interval as one HARQ response and does not indicate the resources wasted by the current transmission, it is not easy to reduce wasted resources. I can.

Meanwhile, in embodiments, the transmission parameter may include a parameter related to an effective code rate and/or a parameter related to HARQ (eg, a parameter related to retransmission). 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-described problem, 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 reception unit included in the base station), and a transmission parameter may be set by the base station. Therefore, even if the HARQ operation (for example, the feedback operation of the HARQ response) is disabled in the uplink transmission procedure, the base station provides a HARQ response (for example, ACK) based on the decoding result for the uplink data received from the terminal. Alternatively, NACK) can be generated, and transmission parameters can 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, RRC message, MAC message, and PHY message. In order 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 a terminal (eg, a receiver included in the terminal), and a transmission parameter 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 the transmission parameter.

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). Accordingly, the base station can estimate the HARQ response for downlink data (hereinafter referred to as "downlink HARQ response") based on the HARQ response for 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 can predict the downlink HARQ response using the uplink HARQ response. Here, the metric may be one or more of an effective code rate, spectrum 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 a decoding result.

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

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 at least one of M transmissions and/or probability moment values such as averages and deviations over time N, a minimum value, a maximum value, an average value, and a difference. The probability moment value used as statistical information may be set in advance. When M or more samples (eg, TBs) are 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 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 can be set in advance. M can 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 UE 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 set in advance. For example, the base station may determine the information element(s) used as statistical information, and the determined information element(s) is used as the terminal by using one or a combination of two or more of system information, RRC message, MAC message, and PHY message. I can tell you. Alternatively, the terminal may determine the information element(s) used as statistical information, and may 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 statistical information may be set in advance. For example, the base station may determine a transmission time of statistical information, and inform the terminal of the determined transmission time through one or a combination of two or more of system information, RRC message, MAC message, and PHY message.

Alternatively, the terminal may determine a transmission time of 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, RRC message, MAC message, and PHY message. In this case, the base station may reset the transmission parameter in consideration of the transmission time set by the terminal.

The terminal may transmit an information element necessary for setting a 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 or not 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 efficient (hereinafter, referred to as "efficiency information") is a combination of one or more of an RRC message, a MAC message, and a PHY message. It can be transmitted to the base station through. The base station may receive the efficiency information from the terminal and may reset the transmission parameter 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 occurrences in the aggregated transmission interval is more than one, the terminal may determine that the transmission parameter needs to be changed. 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 in a direction in which the aggregation factor decreases among valid code rate related parameters, and the corresponding information may be indicated by efficiency information. Here, conditions for determining that the transmission parameter needs to be changed may be variously changed, such as "the average of the number of successful decryption is more than 1.5", "the average of the number of successful decryption is more than two".

When the average of the number of successful decoding occurrences in the aggregated transmission interval is 1, 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".

If the average of the number of successful decoding in the aggregated transmission interval is less than 1, the terminal may determine that the transmission parameter needs to be changed. 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 transmission parameter in a direction in which the effective code rate decreases. For example, it may be necessary to change in a direction in which the aggregation factor increases among valid code rate related parameters, and the corresponding information may be indicated by efficiency information. Here, the conditions for determining that the transmission parameter needs to be changed may be variously changed, such as "the average of the number of successful decoding is less than 0.5", "when the number of successful decoding does not occur", and the like.

The above-described embodiment may be performed for not only the aggregation factor but also other parameters. In this case, the execution order or priority may be set in advance. For example, the base station may determine the execution order or priority of the efficiency information generation/transmission operation, 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. It can be notified to the terminal through Alternatively, the terminal may determine the execution order or priority of the efficiency information generation/transmission operation, 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. I can.

Meanwhile, the transmission time of the efficiency information may be set in advance. For example, the base station may determine a transmission time of the efficiency information, and may inform the UE 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 a 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 efficiency information feedback procedure, information indicating that a change of a transmission parameter is required, a changed transmission parameter (e.g., 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 the transmission parameter may be transmitted.

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

The comparison criterion (eg, metric) used to determine the efficiency of the transmission parameter may be a target error rate, throughput, latency, and/or 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. The value of the metric used to determine the efficiency of the transmission parameter may be indicated by an upper layer. The value of the metric used to determine the efficiency of the transmission parameter may be set in advance. For example, the base station can determine the value of the metric used to determine the efficiency of the transmission parameter, and inform the determined value to the terminal through one or a combination of two or more of system information, RRC message, MAC message, and PHY message. I can. Alternatively, the UE may determine a value of a metric used to determine the efficiency of the transmission parameter, and may 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 change of transmission parameters

The terminal can generate statistical information on the decoding result and can transmit the 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 set in advance. The base station may determine the transmission time of the reset transmission parameter (or guide information on 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 a transmission time of the reset transmission parameter (or guide information on the reset transmission parameter), and the determined transmission time is a base station through one or a combination of two or more of an RRC message, a MAC message, and a PHY message. I can tell you.

The guide information for changing the transmission parameter may be used as a guideline for determining a transmission parameter to be changed and/or a value to be changed of the transmission parameter. The transmission parameter transmitted as guide information for changing the transmission parameter may be set in advance. 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, RRC message, MAC message, and PHY message. Alternatively, the terminal may determine a transmission parameter used as guide information for changing the transmission parameter, and may 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 feedback procedure of the guide information, at least one of information indicating that the transmission parameter needs to be changed, the changed transmission parameter, the transmission parameter that needs to be changed, and the 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 the transmission parameter may be transmitted.

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

For example, the metric used to determine whether or not 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 intervals. In this case, if the average of the number of successful decoding occurrences in the aggregated transmission interval is more than one, the terminal may determine that the transmission parameter needs to be changed and 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 reduction of an aggregation factor among parameters related to an effective code rate. However, when the aggregation factor is already set to the minimum value, the guide information may suggest changing another parameter among valid code rate related parameters. Here, conditions for determining that the transmission parameter needs to be changed may be variously changed, such as "the average of the number of successful decryption is more than 1.5", "the average of the number of successful decryption is more than two".

If the average of the number of successful decoding occurrences in the aggregated transmission interval is 1, 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 the transmission parameter needs to be changed and transmit guide information of the transmission parameter to the base station. Here, the guide information may suggest reduction of the effective code rate. For example, the guide information may suggest an increase in an aggregation factor among parameters related to an effective code rate. However, when the aggregation factor is already set to the maximum value, the guide information may suggest changing other parameters among the valid code rate related parameters. Here, the conditions for determining that the transmission parameter needs to be changed may be variously changed, such as "the average of the number of successful decoding is less than 0.5", "when the number of successful decoding does not occur", and the like.

The above-described embodiment may be performed for not only the aggregation factor but also other parameters. In this case, the execution order or priority may be set in advance. For example, the base station may determine the execution order or priority of the guide information generation/transmission operation, 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. It can be notified to the terminal through Alternatively, the terminal may determine the execution order or priority of the guide information generation/transmission operation, 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. I can.

8 is a flow chart showing 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 in the same or similar to the communication node 300 shown in FIG. 3. The retransmission method illustrated in FIG. 8 may be performed based on a slot aggregation method. For example, the same TB may be repeatedly transmitted in an aggregated transmission period (eg, slots indicated by SAF). TBs repeatedly transmitted in one aggregated transmission period may have different RVs.

The transmitting node may set a transmission parameter (S801). The transmission parameter may include a parameter related to an effective code rate and/or a parameter related to HARQ. The transmitting node may transmit the transmission parameter 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 transmissions of TBs in one aggregated transmission interval, and the receiving node may set the transmission parameter according to the number of receptions of TBs 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 TB as much as SAF in the aggregated transmission period. For example, the transmitting node may compare the number of transmissions of the TB and the SAF in the aggregated transmission period (S809-1). When the number of TB transmissions 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 transmit the TB to the receiving node based on the reset transmission parameter ( S804). On the other hand, if the number of TB transmissions in the aggregated transmission interval is the same as the SAF, the transmitting node may terminate the transmission operation in the aggregated transmission interval, and the transmission operation in the new aggregated transmission interval (e.g., for a new TB) A transmission operation) may be performed (S810). In the newly aggregated transmission period, the transmission operation may be performed based on steps S801, S802, S803, S804, and S809-1.

Meanwhile, the receiving node may perform a TB receiving operation 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 in units of 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 above-described method. 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 point. In this case, the receiving node may determine that the feedback condition is satisfied when the 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 the need to reset the transmission parameter. 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 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 a feedback condition is not satisfied in one aggregated transmission interval, statistical information, efficiency information, and/or guide information may not be transmitted before the end of one aggregated transmission interval. Alternatively, statistical information, efficiency information, and/or guide information may be transmitted irrespective of the feedback condition. If steps S806 to S808 are performed after step S805, the entire communication procedure can be performed without a problem. The execution timing of steps S806 to S808 may not be limited to the embodiment illustrated in FIG. 8.

The transmitting node may receive statistical information, efficiency information, and/or guide information from the receiving node, and may reset the transmission parameter in consideration of statistical information, efficiency information, and/or guide information. The reset transmission parameter may be transmitted to the receiving node. When statistical information, efficiency information, and/or guide information is received from the receiving node before the end of the aggregated transmission section #n, the transmitting node uses the aggregated transmission section #n with statistics information, efficiency information, and/or guide information. It may not be applied to the transmission operation for.

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

Meanwhile, after performing step S807 or S808, the receiving node may compare the number of times of reception of the TB and the SAF in the aggregated transmission period (S809-2). If the number of TB receptions in the aggregated transmission period is less than the SAF, the receiving node may reset the transmission parameter according to the number of receptions of the TB (S803), and may perform a TB reception operation based on the reset transmission parameter. . On the other hand, if the number of TB transmissions in the aggregated transmission interval is the same as the SAF, the receiving node may end the reception operation in the aggregated transmission interval, and a reception operation in the new aggregated transmission interval (e.g., reception of a new TB) Operation) can be performed (S810). In the newly aggregated transmission period, the reception operation may be performed based on steps S802 to S809-2.

9 is a flowchart showing 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 in the same or similar to the communication node 300 shown in FIG. 3. The retransmission method illustrated in FIG. 9 may be performed based on a slot aggregation method. For example, the same TB may be repeatedly transmitted in an aggregated transmission period (eg, slots indicated by SAF). TBs repeatedly transmitted in one aggregated transmission period may have different RVs.

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

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

The HARQ response transmitted in step S910 may include decoding results for each of all TBs received in the aggregated transmission period. As another example, if the decoding results for all TBs received in the aggregated transmission period are CRC failure, the HARQ response transmitted in step S910 may be NACK. As another example, when the decoding result for at least one TB received in the aggregated transmission period 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 check 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 has been successfully received by the receiving node, and may perform a transmission operation of a new TB in the next aggregated transmission period (S912). Alternatively, if the 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 retransmission operation of the TB based on the reset transmission parameter. The receiving node that has transmitted the ACK in step S910 may perform a new TB reception operation in the next aggregated transmission period (S912).

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

10 is a flowchart showing 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 in the same or similar to the communication node 300 shown in FIG. 3.

The retransmission method illustrated in FIG. 10 may be a general retransmission method rather than a blind retransmission method. That is, in the embodiment illustrated 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.

Meanwhile, 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). In the embodiment shown in FIG. 10, since the HARQ response to the TB is transmitted, 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 check 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). The transmission parameter for the new TB may be set in consideration of statistical information, efficiency information, and/or guide information received from the receiving node. Alternatively, if the 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 retransmission operation of the TB based on the reset transmission parameter. Here, the transmission parameter 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 a problem. The execution timing of 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 TB, the entire communication procedure can be performed without a problem.

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

The HARQ feedback operation may be partially enabled or disabled by a specific granularity (eg, a logical channel identifier (LCID), HARQ processor). In this case, separate transmission parameters may be set for each "Granularity", "Granularity Subset", or "Granularity Group", and a retransmission method may be managed. . When the HARQ feedback operation is partially enabled or disabled, the 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 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 machine language codes such as those produced by a compiler, as well as 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 (1)

A method of operating a first communication node in a communication system, comprising:
Receiving one or more TBs (transport blocks) from a second communication node based on a transmission parameter in an aggregated transmission period #n;
Generating decoding results for the 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,
Wherein n is a natural number, the operating method of the first communication node.

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