Apparatus and method for transmitting data in a wireless communication system

Abstract

The disclosure relates to a fifth generation (5G) or pre-5G communication system to support a higher data transmission rate beyond a fourth generation (4G) communication system such as long term evolution (LTE). According to various embodiments of the disclosure, in a wireless communication system, a base station includes at least one transceiver and at least one processor coupled to the at least one transceiver. The at least one processor can be configured to: control the at least one transceiver to transmit first data based on a first hybrid automatic request (HARQ) process, control the at least one transceiver to transmit second data based on the first HARQ process, generate third data based on a result of the first data being received after the second data is transmitted, and control the at least one transceiver to transmit the third data based on a second HARQ process.

Description

Technical Field

[0001] This disclosure generally relates to wireless communication systems, and more specifically, to apparatus and methods for transmitting data in wireless communication systems. Background Technology

[0002] Since the commercialization of fourth-generation (4G) communication systems, efforts have been ongoing to develop enhanced fifth-generation (5G) communication systems, or pre-5G communication systems, to meet the ever-increasing demand for wireless data traffic. For this purpose, 5G communication systems, or pre-5G communication systems, are referred to as beyond-4G network communication systems or post-Long Term Evolution (LTE) systems.

[0003] 5G communication systems are envisioned to be implemented in ultra-high frequency (millimeter-wave) bands (e.g., the 60 GHz band) to achieve high data transmission rates. For 5G communication systems, technologies such as beamforming, massive MIMO, full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and large antennas are being discussed to mitigate path loss of radio waves and increase transmission distance in the ultra-high frequency band.

[0004] In addition, technologies for Evolved Small Cell, Advanced Small Cell, Cloud Radio Access Network (RAN), Ultra-Dense Network, Device-to-Device Communication (D2D), Wireless Backhaul, Mobile Network, Cooperative Communication, Coordinated Multipoint (CoMP), and Interference Cancellation are being developed for 5G communication systems to enhance the network of the system.

[0005] In addition, hybrid frequency shift keying and orthogonal amplitude modulation (FQAM) and sliding window superposition coding (SWSC) as advanced coding and modulation (ACM) schemes, as well as filter bank multicarrier (FBMC), non-orthogonal multiple access (NOMA) and sparse code multiple access (SCMA) as enhanced access technologies in 5G systems are being developed.

[0006] In wireless communication environments, both the transmitting and receiving ends are required to ensure the reliability of transmission over the wireless channel. To achieve this, base stations or terminals can use retransmission and error correction techniques at various layers. Specifically, base stations or terminals can use a hybrid Automatic Repeat Request (HARQ) method to identify whether the data received by the physical layer contains undecodeable errors. This method combines forward error correction (FEC) and automatic repeat request (ARQ) and can request retransmission when errors occur, thereby enhancing performance.

[0007] In wireless communication environments, both the transmitting and receiving ends are required to ensure the reliability of transmission over the wireless channel. To achieve this, base stations or terminals can use retransmission and error correction techniques at various layers. Specifically, base stations or terminals can use a hybrid Automatic Repeat Request (HARQ) method to identify whether the data received by the physical layer contains undecodeable errors. This method combines forward error correction (FEC) and automatic repeat request (ARQ) and can request retransmission when errors occur, thereby enhancing performance. Summary of the Invention

[0008] Technical issues

[0009] Based on the above discussion, this disclosure provides apparatus and methods for addressing throughput degradation in wireless communication systems caused by a relative shortage of Hybrid Automatic Request (HARQ) identifiers (IDs).

[0010] Furthermore, this disclosure provides processes for preventing throughput degradation in environments where inter-cell delays occur in systems utilizing carrier aggregation (CA), and processes for performing retransmissions for this purpose.

[0011] Furthermore, this disclosure provides a process for preventing throughput degradation in an environment where inter-cell delay occurs in a system utilizing inter-cell carrier aggregation (CA) that utilizes different time-frequency basic units (parameter sets), and a process for its retransmission.

[0012] Technical solution

[0013] According to various embodiments of the present disclosure, a method for a base station in a wireless communication system may include: transmitting first data based on a first Hybrid Automatic Request (HARQ) procedure; transmitting second data based on the first HARQ procedure; generating third data based on a result of receiving the first data after transmitting the second data; and transmitting the third data based on a second HARQ procedure.

[0014] According to various embodiments of the present disclosure, a base station in a wireless communication system may include: at least one transceiver; and at least one processor coupled to the at least one transceiver, wherein the at least one processor may be configured to: control the at least one transceiver to transmit first data based on a first Hybrid Automatic Request (HARQ) procedure; control the at least one transceiver to transmit second data based on the first HARQ procedure; generate third data based on the reception result of the first data after transmitting the second data; and control the at least one transceiver to transmit the third data based on a second HARQ procedure.

[0015] Beneficial effects of the invention

[0016] The apparatus and methods according to various embodiments of this disclosure can address performance degradation caused by a shortage of Hybrid Automatic Request (HAQR) identifiers (IDs), thereby enhancing the downlink performance of communication systems.

[0017] Furthermore, the apparatus and methods according to various embodiments of this disclosure can adaptively operate the HARQ processing process according to channel conditions, thereby enhancing communication performance.

[0018] The effects achieved in this disclosure are not limited to those mentioned above. Based on the description provided below, those skilled in the art will clearly understand other effects not mentioned above. Attached Figure Description

[0019] Figure 1a and Figure 1b This is a diagram illustrating examples of wireless communication environments according to various embodiments of the present disclosure;

[0020] Figure 2 This is a diagram illustrating examples of radio resource domains of wireless communication systems according to various embodiments of the present disclosure;

[0021] Figure 3 This is a diagram illustrating an example of the structure of a wireless protocol in a wireless communication system according to various embodiments of the present disclosure;

[0022] Figure 4a , Figure 4b and Figure 4c This is a diagram illustrating examples of existing Hybrid Automatic Request (HARQ) process techniques according to various embodiments of the present disclosure;

[0023] Figure 5 This is a diagram illustrating examples of opportunity-based HARQ techniques according to various embodiments of the present disclosure;

[0024] Figure 6 This is a diagram illustrating examples of retransmissions in a HARQ process based on transmission opportunities according to various embodiments of the present disclosure;

[0025] Figure 7 This is a diagram illustrating another example of retransmission of a HARQ process based on transmission opportunities according to various embodiments of the present disclosure;

[0026] Figure 8 This is a block diagram illustrating an example configuration of mapping information between the HARQ process and the transmitted data according to various embodiments of the present disclosure;

[0027] Figure 9 This is a flowchart illustrating an example operation flow of a base station for a HARQ process according to various embodiments of the present disclosure;

[0028] Figure 10a and Figure 10b This is a diagram illustrating the New Data Indicator (NDI) mismatch caused by the loss of the Physical Downlink Control Channel (PDCCH);

[0029] Figure 11 This is a diagram illustrating the operation of a base station for performing a transmission process for each HARQ procedure according to various embodiments of the present disclosure;

[0030] Figure 12a and Figure 12b This is a flowchart illustrating example operations of a base station for configuring an adaptive servicing HARQ process group according to various embodiments;

[0031] Figure 13 This is a block diagram illustrating an example configuration of a base station in a wireless communication system according to various embodiments of the present disclosure; and

[0032] Figure 14 This is a block diagram illustrating an example configuration of a terminal in a wireless communication system according to various embodiments of the present disclosure. Detailed Implementation

[0033] The terminology used in this disclosure is for describing various exemplary embodiments and is not intended to limit the scope of other embodiments. Unless otherwise stated, singular terms may include plural forms. All terms used herein, including technical or scientific terms, may have the same meaning as commonly understood by those skilled in the art. It will also be understood that terms defined in dictionaries may be interpreted as having the same or similar meaning in the context of the relevant related art, rather than an idealized or overly formal meaning, unless expressly so defined herein. In some cases, even if a term is defined in this disclosure, it should not be construed as excluding embodiments of this disclosure.

[0034] In the various embodiments of this disclosure described below, hardware-based methods will be described by way of example. However, the various embodiments of this disclosure include techniques using both hardware and software, and therefore software-based methods are not excluded.

[0035] The disclosure described below relates to apparatus and methods for wireless communication retransmission processes. For example, this disclosure describes data transmission and retransmission processes in a wireless communication system, and also describes solutions for adaptively utilizing the process in conjunction with existing operations.

[0036] As used herein, terms related to carrier aggregation (CA) (e.g., cell, special cell (SpCell), primary cell (pCell), secondary cell (SCell), frequency range (FR), etc.), terms related to transmission / retransmission techniques (e.g., Automatic Repeat Request (ARQ), Hybrid ARQ (HARQ), HARQ procedure, acknowledgment (ACK), non-acknowledgment (NACK), etc.), terms indicating signals (e.g., reference signal, system information, control signal, message, data), and terms indicating network entities (e.g., communication node, radio node, radio unit, network node, master node (MN), secondary node (SN), transmit / receive point (TRP), digital unit (DU), radio unit (RU), massive MIMO unit (MMU)) are merely examples for ease of explanation. Therefore, this disclosure is not limited to the terms described below, and other terms with the same technical meaning may be used.

[0037] Furthermore, this disclosure uses terminology defined in some communication standards (e.g., the 3rd Generation Partnership Project (3GPP)) to describe various embodiments, but these embodiments are merely examples. The various embodiments of this disclosure can be readily modified and applied to other communication systems.

[0038] Furthermore, in this disclosure, the expressions “greater than” or “less than” can be used to determine whether a specific condition is met or fulfilled; however, these are only used to express an example and do not exclude the expression “greater than or equal to” or “less than or equal to”. The condition described by “greater than or equal to” can be replaced by “greater than”, the condition described by “less than or equal to” can be replaced by “less than”, and the condition described by “greater than or equal to and less than” can be replaced by “greater than and less than or equal to”.

[0039] This disclosure generally relates to wireless communication systems, and more specifically, to apparatus and methods for reducing transmission delays caused by limitations of the HARQ process ID in wireless communication systems. In the following, it will be described through... Figure 1a , Figure 1b , Figure 2 and Figure 3 This describes the wireless communication environment, radio resources, and wireless protocols to explain the wireless communication system of this disclosure.

[0040] Figure 1a and Figure 1b This is a diagram illustrating examples of wireless communication environments according to various embodiments of the present disclosure. (Refer to...) Figure 1a Base station 110 and terminal 120 are shown as parts of a node using a wireless channel in a wireless communication system. Terminal 120 can connect to multiple base stations. (Reference) Figure 1bBase stations 110-1, 110-2, ..., 110-n can be connected to terminal 120 via multiple connections (e.g., dual connections (DC)). In the following description, operation according to various embodiments will be described with reference to base station 110; however, for ease of explanation, the description of base station 110 will be applied to base stations 110-1, 110-2, ..., 110-n in the same or similar manner.

[0041] Base station 110 is network infrastructure that provides radio access to terminal 120. Base station 110 has a coverage area defined as a predetermined (e.g., specified) geographical area based on signal transmission distance. The term "coverage" as used below may refer to the service coverage area of ​​base station 110. Base station 110 may cover one cell or multiple cells. Multiple cells may be distinguished herein by supporting frequencies and the area of ​​the coverage sector.

[0042] Besides being a base station, base station 110 may be referred to as an "access point (AP)," "eNodeB (eNB)," "fifth-generation node (5G node)," "5G node B (NB)," "next-generation node B (gNB)," "radio point," "transmit / receive point (TRP)," "distributed unit (DU)," "radio unit (RU)," "remote radio headend (RRH)," or other terms with the same technical meaning as those mentioned above. According to various embodiments, base station 110 may be connected to one or more "transmit / receive points (TRPs)." Base station 110 can transmit downlink signals to terminal 120 through one or more TRPs, or receive uplink signals through one or more TRPs.

[0043] Terminal 120 is a device used by a user and performs communication with base station 110 via a wireless channel. Depending on the circumstances, terminal 120 can operate without user intervention. That is, at least one terminal 120 can be a device performing machine-type communication (MTC) and may not be carried by the user. Besides "terminal," terminal 120 may also be referred to as "user equipment (UE)," "mobile station," "subscriber station," "customer premises equipment (CPE)," "remote terminal," "wireless terminal," "electronic device," "vehicle terminal," "user equipment," or other terms with the same technical meaning as those mentioned above.

[0044] Dual connectivity (DC), a type of multi-connectivity technology, was introduced from 3GPP Standard Release 12. Dual connectivity connects a terminal to two independent wireless communication cell groups of different or the same type. These two independent cell groups have separate radio resource control entities and utilize frequency resources on component carriers of cells within their respective cell groups, located in different frequency bands, to enhance frequency utilization efficiency for both the terminal and the base station. Dual connectivity can be configured with a primary cell group and a secondary cell group. The primary cell group manages the radio resource control status of terminals with direct connection to the core network's control plane, while the secondary cell group is interlocked with the primary cell group.

[0045] Carrier aggregation (CA) technology was introduced in 3GPP Standard Release 10. CA is a technology that connects a terminal to a group of wireless communication cells of the same kind with a common radio resource control entity, and uses frequency resources on component carriers of corresponding cells located in different frequency bands simultaneously in signal transmission and reception to enhance the frequency utilization efficiency of the terminal and the base station.

[0046] Due to the technological advantages of enhanced efficiency in utilizing the limited wireless communication resources of both the terminal and the base station, research on dual connectivity and carrier aggregation technologies is actively being conducted from an academic perspective. Specifically, 5G mobile communication systems employ a non-independent approach, operating by interlocking with the 4G core network, as their basic operating method. Therefore, dual connectivity and carrier aggregation can be used as core technologies to support commercial services of 5G mobile communication systems.

[0047] Communication nodes (e.g., terminals, base stations, core network entities) according to various embodiments of this disclosure can operate in an LTE system. Furthermore, communication nodes (e.g., terminals, base stations, core network entities) according to various embodiments of this disclosure can operate in an NR system. Moreover, communication nodes (e.g., terminals, base stations, core network entities) according to various embodiments of this disclosure can operate in both LTE and NR systems. Figures 1a to 3 The explanation of the structure and layers shown is merely an example; any communication system can be used to explain other communication systems.

[0048] Figure 2 This is a diagram illustrating examples of a radio resource domain in a wireless communication system according to various embodiments of the present disclosure. In various embodiments, the radio resource domain may include a time-frequency domain structure. In various embodiments, the wireless communication system may include an LTE communication system or an NR communication system.

[0049] Reference Figure 2In the radio resource domain, the horizontal axis indicates the time domain, and the vertical axis indicates the frequency domain. A radio frame can be a time-domain portion consisting of 10 subframes. The smallest transmission unit in the time domain can be an Orthogonal Frequency Division Multiplexing (OFDM) and / or Discrete Fourier Transform Spread Spectrum OFDM (DFT-s-OFDM) symbol, and can be aggregated to form a time slot of 202 N. symb A number of OFDM and / or DFT-s-OFDM symbols 201. In various embodiments, OFDM symbols may include symbols relating to the transmission and reception of signals using OFDM multiplexing methods, and DFT-s-OFDM symbols may include symbols relating to the transmission and reception of signals using DFT-s-OFDM or single-carrier frequency division multiple access (SC-FDMA) multiplexing methods. Hereinafter, for ease of explanation, embodiments relating to OFDM symbols will be described, but these embodiments can be applied to embodiments relating to DFT-s-OFDM symbols. The smallest transmission unit in the frequency domain is a subcarrier, and the carrier bandwidth forming the resource grid can be a total of N SC BW A number of subcarriers 205 are formed. Furthermore, in this disclosure, for ease of explanation, embodiments relating to downlink signal transmission and reception will be described; however, these embodiments can be applied to embodiments relating to uplink signal transmission and reception.

[0050] In various embodiments, the number of time slots 202 forming a subframe 203 and the length of the time slots 202 can vary depending on the subcarrier spacing. The subcarrier spacing can be referred to as a parameter set (μ). That is, the subcarrier spacing, the number of time slots included in the subframe, the time slot length, and the subframe length can be configured differently. For example, when the subcarrier spacing (SCS) in the NR communication system is 15 kHz, one time slot 202 can form one subframe 203, and the lengths of both time slot 202 and subframe 203 can be 1 millisecond. Alternatively, for example, when the subcarrier spacing is 30 kHz, two time slots can form one subframe 203. In this case, the time slot length can be 0.5 milliseconds, and the subframe length can be 1 millisecond.

[0051] In various embodiments, the subcarrier spacing, the number of time slots included in a subframe, the time slot length, and the subframe length can be applied differently depending on the communication system. For example, in the case of an LTE system, the subcarrier spacing can be 15 kHz, and two time slots can form a subframe. In this case, the time slot length can be 0.5 milliseconds, and the subframe length can be 1 millisecond. In another example, in the case of an NR system, the subcarrier spacing (μ) can be one of 15 kHz, 30 kHz, 60 kHz, 120 kHz, and 240 kHz, and the number of time slots included in a subframe can be 1, 2, 4, 8, or 16 depending on the subcarrier spacing (μ).

[0052] In the time-frequency domain, the basic unit of a resource can be a resource element (RE) 206, and the resource element 206 can be expressed as an OFDM symbol index and a subcarrier index. A resource block can include multiple resource elements. In the LTE system, a resource block (RB) (or physical resource block (PRB)) can be generated from N in the time domain. symb The number of continuous OFDM symbols and N in the frequency domain SC RB The number of consecutive subcarriers is used to define this. For example, the number of symbols included in a single RB can be defined by N. symb =14 indicates that the number of subcarriers can be expressed as N. SC RB =12 is the expression. In another example, the number of symbols included in a single RB can be expressed by N. symb =7 indicates that the number of subcarriers can be expressed as N. SCRB =12 expressions. Number of RBs (N) RB The frequency band can be changed according to the system's transmission bandwidth. In an NR system, resource block (RB) 207 can be determined by N in the frequency domain. SC RB The number of consecutive subcarriers is defined by N. SC RB =12. The frequency domain can include Common Resource Blocks (CRBs). Physical Resource Blocks (PRBs) can be defined within the Bandwidth Part (BWP) of the frequency domain. The number of CRBs and PRBs can be determined differently depending on the subcarrier spacing.

[0053] In NR and / or LTE systems, scheduling information regarding downlink or uplink data can be transmitted from the base station to the terminal via downlink control information (DCI). In various embodiments, DCI can be defined according to various formats, and each format can indicate whether the DCI includes scheduling information regarding uplink data (e.g., UL grant) or downlink data (e.g., DL grant), whether the DCI is a compact DCI with small-sized control information or a fallback DCI, whether spatial multiplexing using multiple antennas is applied, and / or whether the DCI is for power control. For example, a DCI format including scheduling control information (DL grant) regarding downlink data (e.g., NR DCI format 1_0) may include at least one piece of information regarding the following control information: NR DCI format 1_0 may include scheduling information regarding downlink data.

[0054] -DCI format identifier: An identifier used to identify the DCI format;

[0055] - Frequency domain resource allocation: Indicates the RBs allocated for data transmission;

[0056] -Time-domain resource allocation: Indicates the time slots and symbols allocated for data transmission;

[0057] -VRB to PRB mapping: Indicates whether Virtual Resource Block (VRB) mapping is applied;

[0058] - Modulation and coding scheme (MCS): Indicates the modulation scheme used for data transmission and the size of the transport block as data to be sent;

[0059] - New Data Indicator (NDI): Indicates whether the transmission is a HARQ initial transmission or a retransmission;

[0060] - Redundant Version (RV): Indicates a redundant version of HARQ;

[0061] -HARQ process number: The process number indicating the HARQ;

[0062] - PDSCH allocation information (downlink allocation index): Indicates the number of PDSCH reception results (e.g., the number of HARQ-ACKs) that the terminal should report to the base station;

[0063] - Transmit Power Control (TPC) Commands for Physical Uplink Control Channel (PUCCH): Commands that indicate the transmit power control of the PUCCH, which serves as the uplink control channel;

[0064] -PUCCH Resource Indicator: Indicates the PUCCH resource used to report HARQ-ACKs, including information about the reception results of the PDSCH configured via the corresponding DCI; and

[0065] -PUCCH Transmission Timing Indicator (PDSCH-to-HARQ_feedback Timing Indicator): Indicates the time slot or symbol information that should be sent for reporting the HARQ-ACK, which includes the result of receiving the PDSCH configured through the corresponding DCI.

[0066] DCI can undergo channel coding and modulation processes and can be transmitted on the Physical Downlink Control Channel (PDCCH) (or control information, which are used interchangeably below) or the Enhanced PDCCH (EPDCCH) (or enhanced control information, which are used interchangeably below), i.e., the downlink physical control channel. In the following description, the transmission and reception of PDCCH or EPDCCH can be understood as the transmission and reception of DCI on PDCCH or EPDCCH, and the transmission and reception of the Physical Downlink Shared Channel (PDSCH) can be understood as the transmission and reception of downlink data on PDSCH.

[0067] In various embodiments, a Cyclic Redundancy Check (CRC) scrambled to a specific Radio Network Temporary Identifier (RNTI) (or Terminal Identifier C-RNTI) independent of each terminal can be added to the DCI, and the DCI for each terminal can be channel-coded, then configured as an independent PDCCH and can be transmitted. In the time domain, the PDCCH can be transmitted during the control channel transmission period. The mapping location of the PDCCH in the frequency domain can be determined by at least one identifier (ID) for each terminal, and can be transmitted in the total system transmission band or some of the system transmission bands.

[0068] Downlink data can be transmitted on the Physical Downlink Shared Channel (PDSCH), which is the physical channel used for transmitting downlink data. The PDSCH can be transmitted after the control channel transmission period, and its frequency domain mapping and scheduling information (such as modulation schemes for the PDSCH) can be determined based on the DCI transmitted via the PDCCH.

[0069] By using the modulation and coding scheme (MCS) in the control information of the DCI, the base station can inform the terminal of the modulation scheme applied to the PDSCH to be transmitted and the size of the data to be transmitted (transmission block size (TBS)). In various embodiments, the MCS can be formed of 5 bits or more or fewer. The TBS can correspond to the size of the TB before the channel coding for error correction is applied to the transport block that the base station intends to transmit.

[0070] In NR systems, modulation schemes supporting downlink data transmission can include at least one of quadrature phase shift keying (QPS), 16-QAM, 64QAM, and 256QAM, and each modulation order (Q... m The number of bits can be 2, 4, 6, or 8. For example, in QPSK modulation, each symbol can transmit 2 bits. In 16QAM modulation, each symbol can transmit 4 bits. In 64QAM modulation, each symbol can transmit 6 bits. In 256QAM modulation, each symbol can transmit 8 bits. Furthermore, depending on the system configuration, 256QAM or higher modulation schemes can be used.

[0071] Various embodiments of this disclosure will be described based on LTE or NR communication systems; however, the disclosure is not limited thereto and can be applied to various wireless communication systems that use retransmission technology. Furthermore, as needed, the disclosure can also be applied to unlicensed frequency bands in addition to licensed frequency bands.

[0072] The disclosure described below relates to signaling methods for transmitting higher-layer signaling or higher signals from a base station to a terminal using a downlink data channel of the physical layer, or from a terminal to a base station using an uplink data channel of the physical layer. This may include at least one of the signaling methods transmitted via Radio Resource Control (RRC) signaling, Packet Data Convergence Protocol (PDCP) signaling, or Media Access Control (MAC) control elements (MAC CE). Furthermore, the higher-layer signaling or higher signals may include system information, such as a System Information Block (SIB), that is commonly transmitted to multiple terminals.

[0073] Figure 3 This is a diagram illustrating an example of the structure of a wireless protocol for a wireless communication system according to various embodiments of the present disclosure. The structure of the wireless protocol shown may be the structure of a wireless protocol for an LTE or NR communication system.

[0074] Reference Figure 3 The wireless protocol includes the PDCP layer 310, RLC layer 320, MAC layer 330, and PHY layer 340 in the terminal and base station. In the case of NR systems, the wireless protocol may also include an SDAP layer for QoS management, although it is not included in the protocol. Figure 3 As shown in the image.

[0075] The main functions of PDCP layer 310 may include some of the following:

[0076] -Header compression and decompression: ROHC only;

[0077] -Transmission of user data;

[0078] - Ordered transmission of upper-layer PDUs;

[0079] -Out-of-order transmission of upper-layer PDUs;

[0080] - Reordering of received PDCP PDUs;

[0081] -Repetitive detection of low-level SDUs;

[0082] -Retransmit PDCP SDU;

[0083] - Encryption and decryption; and

[0084] - Timer-based SDUs are dropped in the uplink.

[0085] In the aforementioned functions, PDCP device reordering refers to the function of reordering PDCP PDUs received at lower layers in an orderly manner based on PCDP sequence numbers (SNs). PDCP device reordering may include the function of transmitting data to higher layers in a reordered sequence, the function of transmitting data directly regardless of the sequence, the function of reordering and recording lost PDCP PDUs, the function of reporting the status of lost PDCP PDUs to the transmitting side, and the function of requesting retransmission of lost PDCP PDUs.

[0086] The main functions of RLC layer 320 may include some of the following:

[0087] -Transmission of upper-layer PDUs;

[0088] - Ordered transmission of upper-layer PDUs;

[0089] -Out-of-order transmission of upper-layer PDUs;

[0090] - Error correction via ARQ;

[0091] - Cascading, segmentation, and reassembly of RLC SDUs;

[0092] - Resegmentation of RLC data PDUs;

[0093] - Reordering of RLC data PDUs;

[0094] -Repeated detection;

[0095] - Protocol error detection;

[0096] -RLC SDU discarded; and

[0097] -RLC is re-established.

[0098] In the above functions, the ordered delivery of RLC devices can refer to the function of orderly delivering RLC SDUs received from lower layers to higher layers. When an RLC SDU is divided into multiple RLC SDUs and received, the ordered delivery of RLC devices can include the function of reassembling RLC SDUs and delivering them.

[0099] The orderly transmission of RCL devices may include the function of reordering received RLCPDUs with reference to the RLC sequence number (SN) or PDCP sequence number (SN), the function of reordering and recording lost RLC PDUs, the function of reporting the status of lost RLC PDUs to the sending side, and the function of requesting retransmission of lost RLC PDUs.

[0100] The ordered delivery of RLC SDUs can include, when a lost RLC SDU is encountered, only delivering the RLC SDUs preceding the lost one in an orderly manner to higher-level functions. Furthermore, the ordered delivery of RLC SDUs can include, when a predetermined timer expires, delivering all RLC SDUs received up to the current time in an orderly manner to higher-level functions, even if a lost RLC SDU has been encountered.

[0101] RLC devices can process RLC PDUs in the order they are received, regardless of the sequence number order (out-of-order delivery), and can pass the RLC PDUs to PDCP devices. When an RLC device receives a segment, it can receive the segment stored in the buffer or the segment to be received later, and can reconfigure a complete RLC PDU, which can then be passed to the PDCP device.

[0102] RLC layer 320 may not include cascading functionality and may perform the functions on MAC layer 330, or may be replaced by multiplexing functions of MAC layer.

[0103] In the above functions, out-of-order delivery of RLC devices can refer to the function of directly delivering RLC SDUs received from lower layers to higher layers regardless of their order. Out-of-order delivery of RLC devices can include the function of reassembling and delivering RLC SDUs when an RLC SDU is segmented into multiple RLC SDUs and received. Out-of-order delivery of RLC devices can include the function of storing the RLC SN or PDCP SN of received RLC PDUs, sorting them, and recording lost RLC PDUs.

[0104] The MAC layer 330 can connect to various RLC layer devices configured in a terminal, and the main functions of the MAC layer can include some of the following:

[0105] - Mapping between logical channels and transport channels;

[0106] - MAC SDU multiplexing / demultiplexing;

[0107] - Scheduling information report;

[0108] - Error correction via HARQ;

[0109] - Priority processing between logical channels of a UE;

[0110] - Priority handling between UEs through dynamic scheduling;

[0111] -MBMS service identity;

[0112] -Transmission format selection; and

[0113] -filling.

[0114] PHY layer 340 can perform the following operations: perform channel coding and modulation on higher-layer data (data corresponding to MAC PDUs), and generate OFDM symbols and transmit OFDM symbols via a wireless channel, or demodulate OFDM symbols received via a wireless channel, perform channel decoding, and transmit the OFDM symbols to higher layers. In this case, the data received from MAC layer 330, which is a higher layer, can be referred to as a transport block (TB).

[0115] Existing wireless communication network systems, including the aforementioned 4G to 5G communication systems, utilize basic techniques such as retransmission technology and error correction coding at each layer to achieve reliable transmission between communication devices such as base stations and terminals. These techniques can be used redundantly at each layer through individual techniques or combinations of multiple techniques at each layer within the system. This can refer, for example, to redundantly and differently implementing multiple retransmission processes according to each layer of a communication system.

[0116] The standards body represented by 3GPP applies this communication principle itself and defines retransmission processes with different characteristics for multiple layers. The standards body not only employs a feedback-based retransmission process based on Automatic Repeat Request (ARQ), but also a Hybrid ARQ (HARQ) technique that combines ARQ and error-correcting coding. During retransmission, different or the same information or its corresponding bits are transmitted, and the information or bits received in response to multiple transmissions are combined to recover the information originally intended to be sent.

[0117] HARQ technology requires the terminal to identify groups of received messages or bits based on the same data information, which necessitates an indicator to notify each retransmission process to recover the same data. Such an indicator can be called a HARQ indicator (HARQ ID). The HARQ ID serves as an indicator allowing the terminal and base station to identify the same data unit or message, and it can notify the terminal that newly received retransmission information should be combined with previously received information bits via the same HARQ ID. The HARQ ID can also be called a HARQ process ID. As described above, such HARQ technology can be implemented at MAC layer 330.

[0118] The MAC entity managing the HARQ process may include a HARQ entity for each serving cell. The HARQ entity is used to manage the HARQ process in parallel and can provide the corresponding HARQ process with the data received at the DL-SCH, i.e., HARQ information related to the Transport Block Size (TB). The HARQ information may include a New Data Indicator (NDI), Transport Block Size (TBS), Redundancy Version (RV), and HARQ process ID. As mentioned above, the HARQ information can be transmitted via the DCI of physical layer 340. In the following, the HARQ process will be used as an expression representing a buffer (e.g., a soft buffer) of the MAC layer used to transmit physical layer transmission signals in the communication protocol, and will be used as an expression representing components of the same or similar concepts.

[0119] Communication systems utilize a technique called carrier aggregation (CA) to increase bandwidth during transmission by combining multiple carriers. This CA technique combines multiple frequency elements and uses these elements to communicate with terminals, thereby enabling a single terminal to achieve higher data throughput. The area of ​​the terminal responsible for the basic frequency element used for operation can be called PCell, SpCell, PSCell, etc., and the area of ​​additional frequency elements used independently in addition to the basic frequency element can be called SCell. PSCell refers to the PCell of the secondary node (SN), and SpCell refers to both pCell and PSCell. SCell refers to a cell other than SpCell.

[0120] In the case of the CA technology described above, the success or failure of receiving downlink transmission data for each SpCell and SCell should be transmitted from the terminal to the base station in the form of HARQ ACK / NACK. In this scenario, in addition to the downlink transmission data being sent to each cell, ACK / NACK information can be combined and transmitted through a specific cell. For example, HARQ ACK / NACK information for SpCell and one or more SCells can be transmitted via the Physical Uplink Control Channel (PUCCH) of the SpCell. HARQ ACK / NACK information can be multiplexed with the PUSCH transmission of the SpCell or a specific SCell and can be transmitted. Furthermore, for example, HARQ ACK / NACK information can be transmitted through an SCell configured with a PUCCH.

[0121] When CA technology is used with the HARQ ACK / NACK delivery method described above, there may be a delay in exchanging information between the cell where the HARQ ACK / NACK information arrives and the cell where the corresponding downlink transmission occurs. For example, there may be a delay in the backhaul network for the cell. Due to the physical separation between the cell to which the HARQ ACK / NACK information is delivered and the cell to which the downlink transmission is provided, information delay may occur in the backhaul network between the two cells. This may occur when CA operation is configured between devices with meaningful delivery delays in information transmission rather than within a single processor or device. For example, in the case of NR communication systems, the parameter sets between cells may differ. As described above... Figure 2 As mentioned, because parameter sets are configured differently between cells, the absolute length between two cells may differ even if the number of symbols or time slots is the same. For example, due to the difference in absolute length between the transmission unit of the channel used to transmit real data and the transmission unit of the feedback channel, the HARQ-ACK information for data related to the HARQ process may arrive at the base station later than the base station expects.

[0122] Due to this delay, until it is identified whether an ACK / NACK has been received on the corresponding downlink transmission, a cell that fails to receive HARQ ACK / NACK information will not cause a change in the operation of the HARQ procedure mapped to the corresponding HARQ ID, and can use retransmission bit combinations according to the HARQ method. Subsequently, when the base station receives NACK information from the corresponding cell, the base station can retransmit bits that are the same as or different from the previous bits, and the terminal can operate to decrypt the original signal by combining the previously transmitted information and the newly received information with the corresponding HARQ ID. For example, the terminal can obtain a combination gain by combining and decoding retransmitted data received in the same HARQ procedure with data from the soft buffer (data received at the corresponding HARQ procedure).

[0123] However, to gain the benefit of HARQ operations in the above-described process, new data (or transport blocks (TB)) should not be passed to the HARQ process corresponding to the HARQ ID. During this process, transmission and retransmission continue until a successful retransmission or the number of retransmissions reaches a predetermined maximum. Furthermore, due to the limitation on the number of HARQ IDs and the delay in ACK / NACK transmission in the aforementioned CA environment, even when there are downlink radio resources and information to be transmitted, this shortage of HARQ IDs can limit the transmission process. Because of the long information transmission delay between the two devices targeted by CA, the limitation on transmission can increase the number of lost transmission opportunities and ultimately lead to a very linear degradation in data throughput. In other words, the limitation on the number of HARQ IDs may limit the number of transmissions that a communication system using HARQ technology can send.

[0124] Using HARQ technology, and considering that these limitations can affect the transmission window size, the base station can continuously transmit data through the transmission window even without a HARQ response. In other words, limitations on the number of HARQ IDs can affect the transmission window size in base station-terminal communication, and when the time delay from transmission to receiving and processing the HARQ response is longer than the time spent processing data within the transmission window size, data may not be able to be transmitted due to insufficient transmission window size.

[0125] HARQ process technology based on transmission opportunities

[0126] To address the aforementioned problems, various embodiments of this disclosure provide novel HARQ procedure techniques for reducing losses caused by latency, rather than HARQ procedure techniques for obtaining combination gain (gain obtained through bit combination). In this disclosure, as a method for addressing the shortage of HARQ IDs that occurs at the receiving end due to data recovery through bit combination via HARQ operation, the existing HARQ procedure can be adaptively maintained, or the separate procedures described in this disclosure can be utilized. In this disclosure, the MAC PDU (or TB) managed in the corresponding HARQ procedure for existing HARQ operation is removed, so that the existing retransmission procedure is not followed, and when a transmission opportunity arises, the HARQ procedure technique between the base station and the terminal can operate by sending a process that replaces the PDU (or TB) in the corresponding HARQ procedure. By following separate retransmission procedures, such as separate HARQ procedures, the HARQ procedure technique between the base station and the terminal can be operated. In other words, the newly provided HARQ process technology may not be used as an ARQ process in a system that supports hybrid ARQ, or it may not apply to existing HARQ processes (the same HARQ ID-based retransmission management process).

[0127] Based on Figure 4a , Figure 4b and Figure 4c (can be called) Figures 4a to 4c The process shown in the diagram describes the existing retransmission process to be replaced in HARQ technology (hereinafter, opportunity-based HARQ technology) according to various embodiments of this disclosure. Figures 4a to 4c This is a diagram illustrating examples of existing HARQ process techniques according to various embodiments of the present disclosure. The base station is composed of... Figure 1a and Figure 1b Base station 110 shows that the terminal is... Figure 1a and Figure 1b Terminal 120 is shown. According to Figures 4a to 4c The existing HARQ process technique shown can use each HARQ process so that no new data is inserted into the corresponding HARQ process and no new transmission is made until the transmission is performed a finite number of times or an ACK message is received regarding the data transmitted in each HARQ process.

[0128] Reference Figure 4aThis illustrates a scenario 400 where a base station and a terminal follow existing HARQ procedure techniques without causing latency issues. As an example, a scenario with a total of eight HARQ procedures is shown. The operation of the base station and terminal is illustrated when they are in an environment ideally suited for operating existing systems. After the first transmission in each HARQ procedure begins, the base station can receive ACK / NACK information for each HARQ procedure, identify the ACK / NACK information, and execute transmission and retransmission processes accordingly. This embodiment is an example when operating with the number of HARQ procedures determined by standards is performed without problems, and illustrates operation between the base station and terminal in a normal single-band communication or low-latency carrier aggregation communication environment. After transmitting the first data (a) of HARQ procedure #0, feedback (ACK) regarding the first data (a) of HARQ procedure #0 arrives before all available HARQ procedures are exhausted. Therefore, the base station can generate the second data (a') of HARQ procedure #0 based on the feedback and can send the second data to the terminal. When the feedback is NACK, the base station can generate the second data for HARQ procedure #0 based on the first data (a), and can send the second data to the terminal, although this... Figure 4a Not shown in the image.

[0129] In such Figures 4a to 4c Operating in the environment shown, there are no problems that should be solved by the embodiments of this disclosure, and in the above environment, priority can be given to suppressing operations as described below in the embodiments of this disclosure (HARQ process technology based on transmission opportunities). Detecting situations where no latency issues occur and performing existing HARQ process technology can also be understood as embodiments of this disclosure.

[0130] Figure 4b and Figure 4c Scenarios 430 and 460 are shown for a base station and terminal performing an existing HARQ procedure technique with latency issue 450. As an example, a scenario showing a total of 8 HARQ procedures is illustrated. Figure 4a Compared to the previous environment, this example illustrates an environment with a HARQ ID shortage problem and the resulting performance degradation that occurs in existing system operations. Figure 4b This shows the process when there is no retransmission request from the receiving terminal. Figure 4c The process is illustrated when a retransmission request is received from the receiving terminal. For example, the operation of the base station and terminal in an existing system is shown when the time-frequency basic units in the corresponding frequency bands of carrier aggregation are different, or when the delay in information transmission between two areas of two frequency bands being processed is relatively long.

[0131] Each HARQ procedure is configured to wait until an ACK message is received regarding the initially transmitted target data or a predetermined number of retransmissions is reached before inserting new data into the corresponding HARQ procedure and performing operations to obtain the HARQ combination gain. Therefore, due to the operation for obtaining the HARQ combination gain and the delay until an ACK message is received, even if time-frequency resources are available for transmission, the transmission process is not initiated using the corresponding resources due to the shortage of HARQ procedures, resulting in reduced system throughput. For example, as... Figure 4b and 4c As shown, after sending the first data (a) of HARQ procedure #0, the base station can wait until feedback on the first data (a) of HARQ procedure #0 arrives. Due to the shortage of HARQ IDs, there may be no further data transmission after HARQ procedure #7. Since feedback on the first data (a) does not arrive after the data transmission of HARQ procedure #7, a delay of 450° may occur in the base station's transmission. After a delay of 450°, the base station can receive feedback. The feedback is ACK (...). Figure 4b ) or NACK ( Figure 4c The base station can determine the data to be included in HARQ procedure #0. When the feedback is ACK, the base station can generate new data (a') as the second data for HARQ procedure #0 and send the second data to the terminal. When the feedback is NACK, the base station can generate the second data for HARQ procedure #9 based on the first data (a) and send the second data to the terminal.

[0132] In order to solve Figure 4b and Figure 4c To address the problems that arise, various embodiments of this disclosure provide methods for retransmission processes that do not conform to existing HARQ operations. These methods execute existing HARQ process techniques. Figure 4b , Figure 4c The process of obtaining combined gain even in the event of latency issues can also be understood as an embodiment of this disclosure. In this case, combined gain can be obtained instead of latency.

[0133] To avoid following the existing HARQ retransmission process, the base station can insert second transmission data into the HARQ process that performs the first transmission or retransmission, where the first transmission data is inserted beforehand, but ACK / NACK information is still not received. That is, when a transmission opportunity arises, the base station can add second transmission data to the corresponding HARQ process. The existing first transmission data may not be used in the corresponding HARQ process. Due to the limitation on the maximum number of HARQ processes, a delay occurs while waiting for a response (HARQ ACK information) to the corresponding HARQ process, even though data needs to be sent. To prevent this, according to various embodiments, the base station can configure the data to be sent via the HARQ process (i.e., TB) regardless of the HARQ ACK information regarding the HARQ process. In other words, when a transmission opportunity for the HARQ process arises, the base station can transmit a new TB to the terminal based on the HARQ process even without receiving a response to the corresponding HARQ process. In the following, this will be explained through... Figure 5 , Figure 6 and Figure 7 The exemplary operation is used to describe the opportunity-based HARQ process technology according to various embodiments of the present disclosure.

[0134] Figure 5 This is a diagram illustrating examples of opportunity-based HARQ technology according to various embodiments of the present disclosure. The base station is composed of... Figure 1a and Figure 1b Base station 110 shows that the terminal is... Figure 1a and Figure 1b Terminal 120 is shown. In the corresponding embodiment, it is assumed that a total of 8 HARQ processes are supported. As a method to avoid performance degradation caused by the HARQ ID shortage problem in existing systems, a process for sending ACK / NACK information independently of latency is shown.

[0135] Reference Figure 5The diagram illustrates a scenario 500 where, after eight consecutive transmissions using HARQ procedures #0 to #7, no HARQ information (ACK / NACK / DTX) regarding the still-in-use HARQ procedures is received. No HARQ information is received as feedback regarding the transmissions through HARQ procedures #0 to #7 before the next transmission time of each HARQ procedure. In the absence of feedback from HARQ procedure #i, the transmission opportunity for HARQ procedure #i arrives. Therefore, the base station can configure the data (e.g., TB) to be inserted into the HARQ procedure according to a transmission opportunity-based HARQ procedure technique. When configuring the transmission data to be included in the HARQ procedure, the base station can configure the transmission data to be included in the HARQ procedure regardless of feedback from previous transmissions of the HARQ procedure (i.e., feedback is not considered). In other words, even when no feedback information is received, the base station can configure the transmission data regardless of whether the previous transmissions were successful or failed.

[0136] Data for HARQ process #0 can be configured using the new first TB 521(a'). Data for HARQ process #1 can be configured using the new second TB 522(b'). Data for HARQ process #2 can be configured using the new third TB 523(c'). Data for HARQ process #3 can be configured using the new fourth TB 524(d'). Data for HARQ process #4 can be configured using the new fifth TB 525(e'). Data for HARQ process #5 can be configured using the new sixth TB 526(f'). Data for HARQ process #6 can be configured using the new seventh TB 527(g'). Data for HARQ process #7 can be configured using the new eighth TB 528(h').

[0137] like Figure 4b or Figure 4c As mentioned above, according to existing HARQ process techniques, new data can only be transmitted after feedback on the first data (a) of HARQ process #0 has been received. However, according to the opportunity-based HARQ technique according to various embodiments of this disclosure, even before receiving feedback on the first data (a) of HARQ process #0, the base station can transmit new data to the terminal as the second data of HARQ process #0. That is, the base station can insert TB(a') as the second transmission data into HARQ process #0 through which the first transmission data TB(a) is transmitted, and can transmit the corresponding TB(a').

[0138] The base station can toggle the New Data Indicator (NDI) bit to indicate that the data to be transmitted through the corresponding HARQ procedure is new data, so as to transmit the second transmission data, and can notify the receiving terminal that the second transmission data is not a retransmission of the first transmission data. That is, the terminal can choose not to combine the second transmission data and the first transmission data, and can choose not to decode. The base station can anticipate that the terminal will delete the content related to the first transmission data of HARQ procedure #0 on which the first transmission data was inserted, and insert new content about the second transmission data. For example, the terminal can delete the content related to the first transmission data from the soft buffer, and can include the content about the second transmission data in the corresponding soft buffer. The terminal can receive the new TB(a') about HARQ procedure #0, and can store the new TB(a'). The above operations relate to a method for configuring a transmission process without HARQ operation in a HARQ-based system, and have been described based on a 3GPP system, and depending on the system, the corresponding elements described above can be replaced by other elements with the same or similar concepts, and can be configured.

[0139] The above operations (based on the HARQ process based on transmission opportunities) can be managed together with HARQ process management techniques to apply only to some HARQ processes, as described below, or they can be applied to all HARQ processes. Such HARQ techniques can reduce latency caused by limitations on the number of HARQ process IDs and can define the HARQ process applied when a second transmission of data corresponding to a HARQ process occurs before receiving ACK / NACK information about the first transmission data. The rule that restricts the insertion of the second transmission data after receiving the ACK information to obtain bit combination gain through the same HARQ process is extended to apply before receiving the ACK / NACK information, and the base station can transmit data without limitations on HARQ operations, thus resolving the problem caused by limitations on the number of HARQ process IDs.

[0140] HARQ retransmission technology based on transmission opportunities

[0141] Since an ACK is received for the first transmitted data in each HARQ process, no retransmission is required, and the operation proceeds without issue. However, when the feedback for a TB in a HARQ process is NACK, it may indicate, for example, that the terminal failed to acquire the corresponding TB. Therefore, the base station is required to retransmit the bits corresponding to the transmitted TB, regardless of physical processing (e.g., even though the NDI or RV of the HARQ information indicates new data). Retransmission techniques that do not utilize HARQ combining gain and are used in conjunction with HARQ will be described below.

[0142] In a system using the HARQ procedure described above, a non-application HARQ transport process can occur by inserting new second transport data into the corresponding process after executing a transport process that utilizes the first transport data of an existing HARQ procedure. However, in this case, when the operation is performed solely by inserting existing data, the retransmission of the first transport data that was replaced at the corresponding layer (typically the MAC layer) may be undesirable. This could refer, for example, to depending on the higher layer (typically the RLC layer, e.g., ...). Figure 3 RLC layer 320) or PDCP layer (e.g., Figure 3 The successful transmission of the corresponding data is restored by the retransmission process on the PDCP layer 310). That is to say, even if the transmission of the first transmission data sent in the HARQ process fails and the NACK information about the corresponding transmission arrives in the HARQ process, retransmission on the corresponding layer may be impossible and there may be no choice but to expect a recovery process executed from a higher layer.

[0143] To mitigate or resolve the aforementioned problems, this disclosure provides a method for replacing the retransmission process for the first transmission data according to existing operations with a separate retransmission process in the process of passing the second transmission data to the HARQ process and deleting the first transmission data awaiting ACK / NACK information according to the HARQ process. This is because the overhead may increase due to delays and retransmissions when retransmission is performed through existing processes at higher layers. In other words, embodiments of this disclosure provide a process for performing a retransmission process at the corresponding layer when NACK information is received at the MAC entity, as a solution to the difficulty of performing a retransmission process at a higher layer when NACK information is received. In the following, it will be explained by... Figure 6 and Figure 7 Describe a specific example.

[0144] Figure 6 This is a diagram illustrating examples of retransmissions using a transmission opportunity-based HARQ process according to various embodiments of the present disclosure. The base station is... Figure 1a and Figure 1b Base station 110 shows that the terminal is... Figure 1a and Figure 1b Terminal 120 is shown. In a corresponding embodiment, it is assumed that a total of 8 HARQ procedures are supported, and a scenario is shown where no HARQ information (ACK / NACK / DTX) regarding the still-in-use HARQ procedures is received after 8 consecutive transmissions using HARQ procedures #0 to #7. As a method to avoid performance degradation caused by the HARQ ID shortage problem in existing systems, a process for performing retransmission based on delayed NACK information according to an embodiment is shown.

[0145] Reference Figure 6 The diagram illustrates a case 600 where the feedback for the first transmitted data (a) of HARQ procedure #0 is NACK. When the feedback 631 for the first transmitted data (a) of HARQ procedure #0 is NACK, the base station can identify the upcoming HARQ procedure after receiving the corresponding feedback. For example, the base station can identify HARQ procedure #3. Since the base station should retransmit TB(a) as the first transmitted data, it can insert TB(a) as the second transmitted data for HARQ procedure #3. The base station can then transmit TB(a) based on HARQ procedure #3.

[0146] Data for HARQ procedure #0 can be configured using the new first TB 621(a'). Data for HARQ procedure #1 can be configured using the new second TB 622(b'). Data for HARQ procedure #2 can be configured using the new third TB 623(c'). Data for HARQ procedure #3 can be configured using the fourth TB 624 corresponding to the existing TB(a). Data for HARQ procedure #4 can be configured using the new fifth TB 625(e'). Data for HARQ procedure #5 can be configured using the new sixth TB 626(f'). Data for HARQ procedure #6 can be configured using the new seventh TB 627(g'). Data for HARQ procedure #7 can be configured using the new eighth TB 628(h'). The terminal may expect to receive new data, but the data actually sent (TB 624) may correspond to the first transmitted data of HARQ procedure #0. That is, from the terminal's perspective, the transmitted data may be new data, but from the base station's perspective, the transmitted data may correspond to the previously transmitted data.

[0147] Because the actual TB content is configured independently of the HARQ procedure ID, the base station may need to manage information about which HARQ procedure is associated with the data received at the MAC layer (MAC SDU or RLC PDU). The base station can determine whether to retransmit the TB or send a new TB based on received feedback (ACK / NACK / NACK) information, independent of the terminal (transparently). The base station may expect the terminal to always recognize the corresponding TB as new data. In other words, the base station can manage retransmissions independently of the HARQ procedure at the MAC layer. The base station can retransmit transmitted data based on the terminal's feedback information without needing higher-layer retransmission procedures (e.g., RLC ARQ) to send the information the base station intends to actually send to the terminal. The HARQ procedure for feedback information and the HARQ procedure for retransmitted transmitted data can be independent of each other and can be configured differently. Even if the terminal is unaware of the retransmission and does not acquire combining gain, the base station can send the data it truly intends to send without delay.

[0148] For example, according to various embodiments of this disclosure, when a MAC Service Data Unit (SDU) sent from a higher layer to the MAC layer or a PDU (e.g., an RLC PDU) generated at a higher layer is sent to the HARQ procedure, the base station can store the corresponding PDU or SDU. In the following, according to embodiments, the PDU or SDU can be an RLC PDU / MAC SDU or a MAC PDU, i.e., a TB. The base station can map the corresponding PDU or SDU to HARQ procedure ID information, wherein the corresponding PDU or SDU is transmitted based on the HARQ procedure ID information, and the mapping information can be stored together with the data. The mapping information can be retained (saved) until an ACK message regarding the transmission of the corresponding PDU or SDU is received, provided that the mapping information has not expired due to various timers applied to the management system or separate events. Reference will be made below. Figure 8 An example of such mapping relationship and mapping information is described in more detail.

[0149] Mapping information is information between a PDU or SDU and a HARQ process ID. It can share the storage space of PDUs or SDUs in the system, or it can directly map PDUs or SDUs to HARQ process IDs. However, the mapping information can be a mapping between at least one of the logical identity information of the PDU or SDU (such as a logical address for storing corresponding PDU or SDU information, a sequence number (SN) defined by a standard, a separate index number defined according to an embodiment, and a HARQ process ID). For example, the base station can store and manage the mapping relationship between the logical number (e.g., index number) of the aforementioned SDU or PDU and the HARQ process ID, and send the SDU or PDU corresponding to that number through the mapping relationship. That is, the above mapping operation is a preparatory step for applying the embodiments of this disclosure, and the base station can perform the mapping operation for all target PDUs or SDUs sent to the HARQ process.

[0150] Furthermore, in embodiments of this disclosure, to more smoothly utilize the transmission of multiple TBs with the same HARQ ID, the base station can additionally map time-related information at the time of generating the corresponding mapping information, i.e., at the time of inserting the PDU or SDU into the HARQ process. The base station can map the time information onto the HARQ ID and then store it as mapping information. This can be an internal counter or a system frame number (SFN), subframe number, time slot number, symbol index of this disclosure, or a combination thereof. Furthermore, in this case, the internal counter can include an indicator indicating whether the corresponding PDU or SDU is replaced during the HARQ process.

[0151] The operation utilizing mapping information is performed for all target PDUs or SDUs, but this disclosure is not limited thereto. In various embodiments, when the second transmission data replaces the first transmission data during the HARQ process, the base station may additionally perform a process of reading information from the first transmission data, thereby performing a mapping operation for some target PDUs or SDUs. The base station may additionally perform an operation to extract index numbers from the first transmission data. The base station may perform mapping by extracting only some data, rather than performing mapping operations for all PDUs or SDUs.

[0152] According to an embodiment, the aforementioned index number may be the sequence number (SN) of the RLC layer. The base station can extract and obtain the corresponding sequence number (SN) from the RLC PDU corresponding to the first transmitted data, and can associate the corresponding SN with the HARQ procedure ID (e.g., HARQ procedure #0) of the first transmitted data. That is, when inserting new data (TB) for the HARQ procedure, the base station can store the mapping relationship between the SN corresponding to the existing data and the corresponding HARQ procedure. In this case, in one embodiment of this disclosure, time information can also be mapped. The base station can additionally map information about the extraction time or transmission time to the mapping relationship information between the data number and the HARQ procedure, and can store the mapping information. In this case, the time information may be an internal counter or system frame number (SFN), subframe number, time slot number, symbol index, or a combination thereof.

[0153] Because the base station stores a mapping relationship between the HARQ process and the data information transmitted during the HARQ process (e.g., RLC PDU / MAC SDU or MAC PDU), it can know the information of the data transmitted earlier in the HARQ process even when new data (TB) is transmitted through the HARQ process. Subsequently, feedback on the data transmitted earlier in the HARQ process can be received. The stored mapping relationship can be utilized when the corresponding PDU or SDU is subsequently transmitted as the first transmitted data and an ACK / NACK is received regarding the transmitted data. When the ACK / NACK information on the corresponding PDU or SDU is received, the HARQ process can pass the ACK / NACK information to the entity managing the mapping information (e.g., the base station or DU). In this case, the mapping information management entity receiving the ACK / NACK information can discover the PDU or SDU that is the entity used to receive the ACK / NACK information at the corresponding time by using the HARQ process ID that sent the ACK / NACK information. That is, the entity discovers the PDU or SDU that includes information about the target, which generates ACK / NACK information through the ACK / NACK information and the HARQ process ID that transmitted the ACK / NACK information. According to an embodiment, when the received ACK / NACK information is ACK, the mapping entity (e.g., a base station) can determine that the corresponding PDU or SDU has been transmitted normally and can remove the mapping information about the corresponding PDU or SDU. For example, the mapping entity can be implemented by the RLC entity of the base station. Furthermore, for example, the mapping entity can be implemented by the MAC entity in the base station. Furthermore, for example, the mapping entity can be implemented in the form of a MAC entity or in the form of a SW block between the RLC / MAC layers. When the mapping information is removed, the information about the corresponding PDU or SDU stored in the buffer can also be removed. On the other hand, when the received ACK / NACK information is NACK, the transmission process on the discovered PDU or SDU can be restarted. For example, the HARQ process that receives NACK information about the first transmission data replaced according to the retransmission process of this disclosure can pass a retransmission indicator to the mapping entity (e.g., the base station). The mapping entity (e.g., the base station) that receives the NACK information can restart the transmission process from the buffer, inserting the transmission data (i.e., TB) on the PDU or SDU that identified the NACK information into the HARQ process.

[0154] like Figure 6As shown, the feedback 631 regarding the first transmitted data (a) of HARQ procedure #0 can be a NACK. The base station receiving the NACK can identify HARQ procedure #0. HARQ procedure #0 can be the HARQ procedure #0 associated with the corresponding feedback. The base station can identify HARQ procedure #0 based on the resource that sent the feedback information and the field of the DCI provided at the time of allocating the corresponding resource (e.g., HARQ procedure number). The base station receiving the NACK information regarding the TB (a) that has been sent through HARQ procedure #0 can read the corresponding data again from the buffer based on the mapping information. The base station can generate a new PDU or SDU from the read data based on the information obtained from the MAC layer. That is, the base station can identify the PDU or SDU mapped to HARQ procedure #0. The base station can regenerate the TB corresponding to the first transmitted data (a) of HARQ procedure #0 based on the identified PDU or SDU. Figure 6 The example shown illustrates that the retransmitted TB is the same as the previously sent TB; however, this is merely an example to explain the principle of retransmission operation and is not intended to limit the embodiment. According to the embodiment, the inserted PDU or SDU may not be exactly the same as the previous PDU or SDU corresponding to the NACK information. Specifically, in this case, the PDU or SDU may be a PDU or SDU with a different bit length due to the PDU or SDU regeneration process used for retransmission.

[0155] When data is retransmitted, the corresponding data can be sent through more robust processing to increase the probability of data transmission. In an embodiment, the corresponding PDU or SDU can be configured for fewer bits or more robust retransmission based on the state of radio resources and the link adaptation process. Furthermore, in an embodiment, the corresponding PDU or SDU can be a PDU or SDU generated based on a transport block size (TBS) calculated by applying a lower MCS. The corresponding PDU or SDU can apply low physical layer processing. In this case, the corresponding PDU or SDU can be multiple PDUs or SDUs configured using PDU or SDU segmentation techniques for retransmission. Figure 7 This disclosure describes embodiments of generating new PDUs or SDUs by applying such a segmentation method and retransmission.

[0156] Figure 7 This is a diagram illustrating another example of retransmission using a transmission opportunity-based HARQ process according to various embodiments. The base station is... Figure 1a and Figure 1b Base station 110 shows that the terminal is... Figure 1a and Figure 1bTerminal 120 is shown. In a corresponding embodiment, it is assumed that a total of 8 HARQ procedures are supported, and a scenario is shown where no HARQ information (ACK / NACK / DTX) is received regarding the still-in-use HARQ procedures after 8 consecutive transmissions using HARQ procedures #0 to #7. A diagram illustrating a method to avoid performance degradation caused by HARQ ID shortages in existing systems is provided. Figure 7 The process of performing retransmission based on delayed NACK information, according to an embodiment, is illustrated (e.g., Figure 6 The process of segmenting the corresponding PDU or SDU and sending it.

[0157] Reference Figure 7 The diagram illustrates a scenario 700 where a corresponding PDU or SDU is retransmitted according to a segmentation technique. The base station can receive NACK information 731 from HARQ procedure #0. Based on the NACK information, the base station can identify the PDU or SDU corresponding to the corresponding HARQ procedure from the buffer. Based on the identified PDU or SDU and information about the MAC layer, the base station can perform retransmission by segmenting the corresponding PDU or SDU into two or more PDUs or SDUs (TB 724, TB 725). The data for HARQ procedure #0 can be configured using a new first TB 721(a'). The data for HARQ procedure #1 can be configured using a new second TB 722(b'). The data for HARQ procedure #2 can be configured using a new third TB 723(c'). The data for HARQ procedure #3 can be configured based on an existing TB(a). The data for HARQ procedure #4 can be configured based on an existing TB(a). The data for HARQ procedure #5 can be configured using a new sixth TB 726(f'). Data for HARQ procedure #6 can be configured using the new seventh TB 727(g'). Data for HARQ procedure #7 can be configured using the new eighth TB 728(h').

[0158] For example, the mapped target PDU or SDU discovered by NACK message 731 and the corresponding HARQ procedure (HARQ procedure #0), along with transmission time information, can be read again from the buffer to perform a retransmission process. One or more PDUs or SDUs obtained from the buffer can be remanaged by the buffer as retransmission SDUs or PDUs. A transmission process can be performed for the segmented PDUs or SDUs according to the defined sequence of segmented PDUs or SDUs, and each of the segmented PDUs or SDUs can be used as a PDU or SDU to start a new transmission process. In this case, the segmented PDUs or SDUs can be configured in the form of newly generated PDUs or SDUs in combination with other data in the buffer. In other words, each of the segmented PDUs or SDUs can include a portion of the information from the previous PDU or SDU. Furthermore, the segmented PDUs or SDUs can be reconfigured to include additional information beyond that included in the existing target PDU or SDU used for segmentation. The HARQ process or HARQ ID selected when inserting a retransmitted PDU or SDU can be a HARQ process (or HARQ ID) selected by a process or HARQ process management and selection process, regardless of previous mapping relationships. In this case, the configuration for transmission can follow the same method as for the first transmission in an ARQ process or HARQ non-application transmission process in a HARQ-supported system as described above (e.g., the transmission of the first transmission data (a) of HARQ process #0).

[0159] According to embodiments, during retransmission, a low MCS can be applied to a more robust transmission. In this context, the expression "lower MCS" refers to a means of reducing transmission errors in the corresponding transmission by using a relatively lower rate, except that MCS can be replaced by elements of the same or similar concept, such as rate, modulation order product code rate (MPR), etc. This expression can be replaced by one or more elements, which may change due to system implementation characteristics or combinations thereof, resulting in variations of elements identical or similar to the aforementioned MCS. In various embodiments of this disclosure, the application of a low MCS for retransmission in a single instance during the retransmission process and the accompanying segmentation process are shown; however, embodiments of this disclosure can be understood by additionally applying a low MCS to a third or fourth retransmission caused by a retransmission failure to perform additional segmentation.

[0160] The segmentation method in this disclosure can be illustrated by the segmentation method and PDU configuration at the RLC layer when the method is described through a specific example of a 3GPP system. Therefore, the method can be expressed as a method for segmenting to the RLC layer and transmitting retransmission indicators, and a method for processing the segmentation process according to the RLC segmentation indicator at the MAC layer. Embodiments of this disclosure may include notifying the retransmission process via an indicator, regardless of the specific layer, and configuring the PDU or SDU accordingly.

[0161] The retransmission process of the opportunity-based HARQ technology according to the various embodiments disclosed above can limit the number of retransmissions, which may be the same as or different from the limitation on retransmissions using existing HARQ. Specifically, when segmented transmission is applied, retransmission counters can be segmented and managed according to the segmentation of the retransmitted PDU or SDU. For example, a PDU or SDU can be segmented into two PDUs or SDUs, and these two PDUs or SDUs can increment two retransmission counters at a time. The counters can be segmented and managed so that the counter does not have 3 retransmission counter values, and the individual counters are each set to 2. This counter is different from the counter in the HARQ process, and the entity that manages the above-mentioned buffers and their mapping relationships can manage the information of the corresponding counters.

[0162] Figure 8 This is a block diagram illustrating an example configuration of mapping information 800 between the HARQ process and transmitted data according to various embodiments of the present disclosure. The entity of the mapping information is an entity managing the MAC layer and may include the MAC entity of the base station. According to embodiments of the present disclosure, after receiving NACK information via corresponding information, the base station can discover the retransmission target data.

[0163] Reference Figure 8 The mapping information 800 may include a HARQ procedure ID 801. The HARQ procedure ID 801 is an identifier indicating the number of the corresponding HARQ procedure. The HARQ procedure ID can be used to identify data IDs, data, and timing information associated with a specific HARQ procedure. The mapping information may include parameters associated with each HARQ procedure ID.

[0164] Mapping information 800 may include data ID 803. Data ID 803 may be an identifier indicating transmitted data. According to an embodiment, the data ID may be an identifier indicating an RLC PDU (or MAC SDU). In this case, the data ID may be the SN of the RLC PDU. Furthermore, according to an embodiment, data ID 803 may be an identifier indicating that TB is a MAC PDU.

[0165] Mapping information 800 may include buffer data 805. Buffer data 805 may include a PDU or SDU corresponding to the corresponding data ID. When NACK information is received, buffer data 805 can be used for retransmission. The base station can identify the HARQ procedure ID corresponding to the received feedback information and can identify the buffer data corresponding to the identified HARQ procedure ID. The base station can perform retransmission based on the identified buffer data.

[0166] In various embodiments, the mapping information may further include timing information 807. Here, the timing information is information about the time when a PDU or SDU is transmitted via the corresponding HARQ procedure ID, and may include the time when a PDU or SDU is mapped to the corresponding HARQ procedure ID (e.g., the time of initial transmission, retransmission, or segmented transmission). Furthermore, the timing information may include the time when a PDU or SDU is extracted from existing data in the HARQ procedure. The timing information may be a system frame number (SFN), subframe number, slot number, or symbol index, or a combination thereof. The base station can use the timing information to know when new data is sent via the HARQ procedure corresponding to the feedback. The base station can identify the relationships between HARQ procedures based on the timing information, and based on this, can configure the transmission data for each HARQ procedure. When TBs are transmitted in parallel via multiple HARQ procedures, the base station can configure the TBs for each HARQ procedure based on the timing information. This is because, depending on the delay, the base station can identify the number of TBs that can be operated in parallel, i.e., the number of scarce HARQ procedures.

[0167] Figure 8 Data in an RLC PDU / MAC SDU or MAC PDU unit is shown, but various embodiments of this disclosure are not limited thereto. In various embodiments, a code block (CB) or code block group (CBG) can be considered a transmission unit, and mapping information can include mapping relationships defined in units of CBs or CBGs. The base station can configure a TB from the mapping relationship based on feedback in bit units of each CBG of the terminal. For example, the base station can receive feedback on HARQ procedure #2 in CBG units. Subsequently, when HARQ procedure #5, in which a transmission opportunity arises, arrives, the base station can configure the TB based on the data corresponding to the CBG as a NACK and new data. The base station can transmit data that is identified as a new TB at the terminal. In this case, the base station can instruct the terminal to clear the soft buffer of the HARQ procedure indicated by the DCI via the CBGFI field of the DCI.

[0168] Figure 9 This is a flowchart illustrating example operation of a base station for a HARQ process according to various embodiments of the present disclosure. The base station is composed of... Figure 1a and Figure 1bBase station 110 is shown. Compared with existing HARQ process techniques based on feedback, the opportunity-based HARQ process technique operates the corresponding HARQ process without considering feedback.

[0169] Reference Figure 9 In step 901, the base station can transmit first data based on a first HARQ procedure. The first HARQ procedure can employ a transmission opportunity-based HARQ procedure technique. Here, the first data may include data that the base station intends to serve a terminal (e.g., referred to as application data, service data, data payload, service packet, information bits, data bits, etc.). In the following, data refers to all data that the base station intends to send to the terminal and is indicated by the TB managed through the HARQ procedure, but is not to be construed as limited to a specific layer's PDU / SDU. According to embodiments, the data can be used as a signal including physical layer control information. The first data may also be transmitted together with physical layer control information regarding the corresponding data. For example, the first data, including the TB and associated HARQ information, may be transmitted together. The HARQ information may include the number of the first HARQ procedure, the NDI of the TB regarding the first data, the RV of the TB regarding the first data, and the TBS of the TB regarding the first data.

[0170] In 903, the base station can send second data based on the first HARQ procedure. When a transmission opportunity arises regarding the first HARQ procedure, the base station can send the second data. The base station can send the second data regardless of the feedback regarding the first HARQ procedure. The base station can generate the second data regardless of whether the feedback regarding the first HARQ procedure is ACK or NACK. The base station can then send the generated second data to the terminal. Even when no feedback is received regarding the corresponding HARQ procedure, the base station can insert new data and execute the downlink transmission process without waiting for feedback, unlike existing HARQ procedure technologies.

[0171] Assume the total number of HARQ procedures operating in the base station and terminal is N. The base station can send data to the terminal in parallel through N HARQ procedures. The base station can send data for each of the N HARQ procedures and can determine the data to be sent again through the first HARQ procedure. According to various embodiments, when the time for sending data through the first HARQ procedure arrives—in other words, after sending data through the last HARQ procedure (e.g., HARQ procedure #N-1)—the base station can detect whether feedback has been received regarding the first HARQ procedure. When no feedback has been received regarding the first HARQ procedure, the base station can determine the transmission of data for the first HARQ procedure regardless of the feedback. This is because there is a transmission delay from the last HARQ procedure to the feedback time while waiting for feedback from the first HARQ procedure. The transmitted data can be second data.

[0172] The second data can be configured in various ways. According to an embodiment, the second data can be newly transmitted, truly new data; that is, new data from both the base station and the terminal's perspective. Furthermore, according to an embodiment, from the terminal's perspective, the second data can be new data (because NDI is switched or RV is initialized), but from the base station's perspective, the second data can be previously transmitted data. In other words, the transmission of the second data can be a retransmission of previously transmitted data that occurred before the first data in the first HARQ process.

[0173] When inserting second data into the first HARQ procedure, the base station can use mapping information. The base station can associate the ID of the first HARQ procedure with the MAC SDU (or RLC SDU) or MAC PDU corresponding to the first transmitted data. The base station can store the mapping information defining the aforementioned association. When the feedback regarding the first HARQ procedure is NACK, the base station can associate the buffer data used for retransmission of the first data with the ID of the first HARQ procedure and can store it. Furthermore, the base station can associate information about the time when the new second data was included in the first HARQ procedure with the ID of the first HARQ procedure and can additionally store this information.

[0174] In step 905, the base station can generate third data based on the reception result of the first data. The base station can obtain the reception result of the first data. The reception result of the first data can be obtained after step 903. The base station can identify the first HARQ procedure from the reception result of the first data. The base station can identify the buffer data associated with the first data corresponding to the first HARQ procedure, or the ID of the first data (e.g., the SN of the RLD header), based on mapping information. When the reception result of the first data is ACK, the base station can clear (or flush) the buffer data associated with the first data. The base station can generate new third data from the perspective of both the base station and the terminal. When the reception result of the first data is NACK, the base station can generate third data based on the buffer data associated with the first data. From the perspective of the base station, the third data can be retransmitted data, but from the perspective of the terminal, the third data can be new data sent through a separate HARQ procedure.

[0175] In step 907, the base station can transmit third data based on a second HARQ procedure. In this case, the second HARQ procedure can be independent of the first HARQ procedure. The HARQ procedure that determines the transmitted data based on feedback from the first HARQ procedure can be configured differently from the first HARQ procedure. The second HARQ procedure can apply ordinary HARQ procedure techniques or opportunity-based HARQ procedure techniques. According to an embodiment, the third data can be transmitted along with HARQ information. The HARQ information may include the number of the second HARQ procedure, the NDI for the TB of the third data, the RV for the TB of the third data, and the TB size of the third data, i.e., the TBS. In this case, the NDI corresponds to the new data in the HARQ procedure from the terminal's perspective, and therefore can be switched compared to the NDI of the previous data in the second HARQ procedure.

[0176] exist Figure 9 The diagram illustrates how a base station considers whether to receive feedback from the first HARQ process when determining the data to be transmitted in the first HARQ process; however, embodiments of this disclosure are not limited to this. According to embodiments, the base station may not execute existing HARQ process techniques regardless of whether real feedback is received, that is, regardless of whether a real delay occurs. In other words, new data can be inserted into the first HARQ process in all cases when the time for transmission via the first HARQ process arrives. Using only ARQ to solve the retransmission problem without performing retransmission at the HARQ entity in the MAC layer can also be understood as an embodiment of this disclosure.

[0177] Figure 9 An example is shown of receiving feedback on the first data in the first HARQ process after the transmission of the second data, but embodiments of this disclosure are not limited thereto. If feedback on the first HARQ process has been received when the time for transmitting data via the first HARQ process arrives, the base station can determine the transmission data for the first HARQ process based on the feedback, according to existing HARQ process techniques. The process of determining whether a feedback delay has occurred, i.e., whether feedback on the first data in the first HARQ process has been received after the transmission of data in the final HARQ process has terminated, can also be understood as an embodiment of this disclosure. Based on whether a delay actually occurs in the corresponding HARQ process, the data to be transmitted via the corresponding HARQ process can be determined. If no delay occurs, the data to be transmitted via the corresponding HARQ process can be configured as new data only when the feedback is ACK, and when the feedback is NACK, the data to be transmitted via the corresponding HARQ process can be configured with existing data for retransmission.

[0178] Already referenced Figures 5 to 9Opportunity-based HARQ procedures are described. When a transmission opportunity arises in a HARQ procedure, the base station can insert new data into the corresponding HARQ procedure without relying on feedback information to determine the data to be inserted. In this case, the HARQ procedure that inserts new data based on the transmission opportunity can be called an opportunity-based HARQ procedure (O-HARQ procedure). The base station can operate multiple HARQ procedures and can configure at least one O-HARQ procedure among multiple HARQ procedures. The following will illustrate this further. Figures 10a to 12b This describes an embodiment for configuring the O-HARQ process.

[0179] HARQ process operation method

[0180] When no HARQ ID (or HARQ procedure) is available, a process that seeks to utilize the aforementioned HARQ combination gain can be transmitted by reusing a certain HARQ ID or HARQ procedure to perform a transmission without HARQ combination gain. In this case, the replacement PDU or SDU can guarantee the reliability of the transmission based on the retransmission process. In the transmission process of this disclosure, the HARQ procedure is basically transmitted by switching NDI. Therefore, regardless of whether the executed transmission is successful, NDI is continuously switched. From the terminal's perspective, this can be a bit used as a means of notifying that new data is being transmitted; however, when control and scheduling information including NDI switching information is not sent to the terminal, a mismatch may exist in the NDI information between the terminal and the base station. This disclosure will be described with reference to the 3GPP system, in which control and scheduling information is transmitted via PDCCH. However, control and scheduling information can be another element with the same or similar meaning. Furthermore, in embodiments of this disclosure, with reference to the 3GPP system, the term "PDCCH lost" can be used to indicate the situation where the aforementioned control and scheduling information is not sent to the terminal, but this term can include the same or similar elements. Figure 10a and 10b Describes the NDI mismatch caused by the PDCCH loss operation.

[0181] Figure 10a and 10b This is a diagram illustrating examples of NDI mismatch caused by PDCCH loss according to various embodiments. Figure 10a and Figure 10b Examples of extreme PDCCH loss scenarios that may occur when embodiments of this disclosure are applied are illustrated, and the success or failure of previous transmissions is shown according to a transmission opportunity-based HARQ process (e.g., Figures 5 to 7 The process of potential NDI mismatch issues.

[0182] Reference Figure 10aThe base station sends data 1001 to the terminal. In this case, the NDI for data 1001 can be "0", and the RV can be "X" (e.g., X = 0, 1, 2, or 3). Afterward, the terminal can send an ACK back to the base station. The base station can configure the first transmitted data 1003 as a new TB, regardless of the feedback. The NDI for the first transmitted data 1003 can be "1", and the RV can be "0". Because the transmitted data is new data, the NDI can be switched, and the RV can be initialized to "0".

[0183] According to the opportunity-based HARQ transmission technology of various embodiments of this disclosure, the base station can send second transmission data 1005 to replace the first transmission data 1003 of the transmission process undergoing HARQ. In this case, the NDI and RV of the second transmission data 1005 can be "0". Because the second transmission data is new data, the NDI can be switched and the RV can be initialized to "0".

[0184] Figure 10a The diagram illustrates the scenario where the last transmitted data 1001, sent before the first transmitted data 1003, is successfully received by the terminal. It also illustrates the scenario where the PDCCH for the first transmitted data 1003 sent by the base station is lost. The terminal may not attempt to decode the first transmitted data 1003 and may ultimately not send ACK or NACK information. Since the second transmitted data 1005 can be configured regardless of feedback on the first transmitted data 1003 in the opportunity-based HARQ technique used to resolve transmission delays, the second transmitted data 1005 can be newly configured. The base station expects the terminal to recognize the second transmitted data as new data. However, when the PDCCH is lost, the terminal may not be aware that NDI has been switched.

[0185] For example, a transmission process based on the opportunity-based HARQ technique according to this disclosure can be applied, and when a new transmission (e.g., the transmission of second transmission data 1005) occurs in the same HARQ process before the ACK / NACK information is delivered to the base station, the base station can switch NDI again and can send that NDI. In this case, a transmission with the same NDI value as a PDU or SUD sent before the PDCCH loss may occur. From the perspective of the terminal where the PDCCH loss occurred, it can be determined that the same information was received through the previous NDI, and in this case, the terminal may misjudge that the new transmission is a retransmission of information received before the PDCCH loss, i.e., a retransmission of data 1001. Due to this misjudge, the terminal can determine that the new information from the base station is a retransmission of a previously received PDU or SDU, and as Figure 10aAs shown, based on the premise that existing information (e.g., data 1001) has been successfully received and ACK information has been sent, the terminal can determine that the new received information is meaningless and can ignore it. Since the corresponding information is ignored, but it is determined that the information has been successfully received, the terminal can transmit ACK information on the corresponding transmission (e.g., second transmission data 1005).

[0186] The base station can receive an ACK in response to new information (e.g., second transmission data 1005). Since the ACK is sent even though the terminal did not normally receive the new information (e.g., second transmission data 1005), the base station may mistakenly determine that the corresponding transmission was successfully executed. As a result, even though the corresponding PDU or SDU was not properly delivered, the base station can consider the corresponding transmission as successful and may not need to perform processes such as retransmission.

[0187] Reference Figure 10b The base station can send data 1051 to the terminal. In this case, the NDI for data 1051 can be "0", and the RV can be "X" (e.g., X = 0, 1, 2, or 3). Afterward, the terminal can send a NACK back to the base station. The base station can configure the first transmitted data 1053 as a new TB, regardless of the feedback. The NDI for the first transmitted data 1053 can be "1", and the RV can be "0". Because the first transmitted data is new data, the NDI can be switched, and the RV can be initialized to "0".

[0188] According to the opportunity-based HARQ transmission technology of various embodiments of this disclosure, the base station can send second transmission data 1055 to replace the first transmission data 1053 of the transmission process undergoing HARQ. In this case, the NDI and RV of the second transmission data 1055 can be "0". Because the second transmission data is new data, the NDI can be switched and the RV can be initialized to "0".

[0189] Figure 10bThe diagram illustrates a scenario where the terminal fails to receive the last transmitted data 1051 sent before transmitting the first transmitted data 1053, and also shows a scenario where the PDCCH of the first transmitted data 1053 sent by the base station is lost. The terminal may not attempt to decode the first transmitted data 1053 and may ultimately not send ACK or NACK information. Since the second transmitted data 1055 can be configured regardless of feedback on the first transmitted data 1053 in the opportunity-based HARQ technique used to resolve transmission delays, the second transmitted data 1055 can be newly configured. The base station expects the terminal to recognize the second transmitted data as new data. However, when the PDCCH is lost, the terminal may not be aware that NDI has been switched.

[0190] With Figure 10a In the same manner, the terminal may misjudge that the new transmission is a retransmission of information received before the PDCCH was lost, i.e., a retransmission of data 1051. Due to this misjudgment, the terminal can determine that the new information from the base station is a retransmission of a previously received PDU or SDU, and since the terminal has not yet successfully decoded the corresponding TB, the terminal can try to decode it by combining the previously received information (e.g., data 1051) with the newly received information (e.g., second data 1055). However, since data 1051 and second data 1055 are generated from truly different TBs, decoding may fail. The base station can receive a NACK regarding the new information (e.g., second transmission data 1055). Subsequently, when NDI is switched, although the existing transmission data 1051 is not well retransmitted, new data can be sent; therefore, the terminal may lose coupling gain.

[0191] The aforementioned problems can be solved through retransmission procedures at higher layers, but this disclosure describes a scheme for preemptively preventing PDCCH loss in order to minimize problems caused by retransmission overhead and other transmission delays at higher layers.

[0192] Configuration of the HARQ process

[0193] The PDUs or SDUs lost due to PDCCH loss can be PDUs or SDUs that execute the transmission process of this disclosure (configuring a new TB regardless of the feedback from the corresponding HARQ process) through the corresponding HARQ procedure after the PDCCH loss occurs, and the aforementioned problem occurs before it can be determined whether the PDCCH loss is relevant. Due to this characteristic, there is no way to resolve the problem caused by PDCCH loss after it occurs, and it may require the base station and terminal to take action to preemptively prevent the problem by reducing the probability of PDCCH loss. This can be achieved by applying a scheme called "conservatization on PDCCH transmission," but conservatization needs to be applied before applying the transmission method of this disclosure, rather than at the time of applying the transmission method. Therefore, this disclosure considers the application of a preemptive PDCCH conservatization scheme.

[0194] By applying this disclosure, in the event that the PDCCH of the first transmission frame replaced during a HARQ process prior to the ACK / NACK message is lost, a preemptive PDCCH conservative scheme can be operated for stable transmission. Therefore, this disclosure describes a process for classifying some of the various HARQ processes into HARQ processes to which this disclosure is applied (hereinafter, opportunity-based HARQ processes or opportunistic HARQ processes (O-HARQ processes)), and other HARQ processes into HARQ processes that follow existing operations without applying the transmission method of this disclosure (hereinafter, feedback-based HARQ processes). The classification of HARQ process types by the base station is shown, but other entities besides the base station may also classify the corresponding HARQ process types.

[0195] According to embodiments of this disclosure, there may be a process for pre-configuring whether an individual HARQ process is the target of this disclosure for HARQ process application. When all HARQ processes or HARQ process IDs are being used, a HARQ process to be selected for sending new data can be chosen from the HARQ processes configured to apply the target group of this disclosure. In this disclosure, the HARQ process that is the target for application can be referred to as a scrambled HARQ process (O-HARQ process). Furthermore, a group including one or more scrambled HARQ processes can be referred to as an O-HARQ process group. According to embodiments of this disclosure, when the transmission opportunity-based HARQ process technology of this disclosure (e.g., Figures 5 to 7When applied to all HARQ procedures, the base station can allocate all available HARQ procedures to the O-HARQ procedure group. According to embodiments, when the opportunity-based HARQ procedure technique of this disclosure is not applied, separate indicators can be transmitted for this purpose, or valid HARQ procedures can be omitted from the O-HARQ procedure group, thus eliminating the need to apply the opportunity-based HARQ procedure technique. According to various embodiments, the base station can apply the above-described opportunity-based HARQ procedure technique to the O-HARQ procedure group (the O-HARQ procedure group is the target of this disclosure) to insert new second transmission data into the corresponding HARQ procedure before receiving ACK / NACK information regarding the first transmission data, and can perform a conservative approach to the corresponding transmission process by applying a lower MCS to the PDCCH transmission, or by allocating more resources relative to sending all data through the corresponding HARQ procedure.

[0196] In embodiments of this disclosure relating to 3GPP systems, the base station can achieve the aforementioned conservative operation by applying a higher aggregation level to the PDCCH used for transmitting O-HARQ process groups than to the PDCCH used for transmitting non-target processes, or by applying greater transmission power. Furthermore, regarding O-HARQ process groups, conservative operation can be applied not only to PDCCH transmission but also to resource allocation and transmission rates for the first transmission.

[0197] In this disclosure, the term "conservatized" or "conservative" can refer to, for example, a state in which a signal is stably transmitted or processed for the stable transmission of a signal. Such a conservatization process can be applied independently of the lower MCS (or the same or similar concept) transmission process applied in the aforementioned retransmission process. That is, compared to sending allocated data to a HARQ process that is not part of the O-HARQ process, the base station can perform O-HARQ process transmissions for the O-HARQ process group with higher reliability.

[0198] In various embodiments, for processes belonging to the O-HARQ process, the base station can execute separate rate control methods and processes with a lower target error probability (target BLER).

[0199] Furthermore, in various embodiments, the conservative processing may employ a low modulation scheme or may include signal processing via a low coding rate. For example, conservative processing may include data processing based on a low MCS level.

[0200] Furthermore, in various embodiments, the conservative processing may include signal processing that induces as many repetitions as possible with the same resources by reducing the size of the data payload (e.g., TBS). According to embodiments, the conservative processing may include configuring the operation of TBs that only include CBGs requiring retransmission, in order to reduce the number of bits transmitted. Furthermore, according to embodiments, the conservative processing may include simply configuring TBs with lower TBS regardless of CBGs.

[0201] Furthermore, in various embodiments, the conservative processing may include configuring the offset with respect to channel quality to have a low error rate. The base station may apply the offset value to an existing MCS or a rate, MPR replaced by an MCS for processes other than the O-HARQ process group, and may apply the MCS rate, MPR, etc. (an offset defined for a given rate, MPR, etc., is applied to that MCS rate, MPR, etc.) to transmit processes within the O-HARQ process group. In this case, the aforementioned offset with respect to MPR and MCS, rate may be a value added to or subtracted from the target value used for application, and may be a value applied in the form of a coefficient multiplied by the target value, or a multiplier in the form of an implementation.

[0202] In the above-described O-HARQ process, when the derived MCS, rate, MPR, or field values ​​that may affect MCS, rate, and MPR are less than or equal to predetermined values, or when an operation indicating a similar environment is detected, the scheme for configuring to not perform the O-HARQ process operation according to embodiments of this disclosure may also be included in this disclosure. Specifically, when the MCS, rate, and MPR on the target terminal are less than or equal to predetermined thresholds, the base station according to various embodiments of this disclosure may not apply the embodiment of this disclosure of inserting new data into the HARQ process before the data transmission in the HARQ process is completed. According to the embodiments, the operation of inserting new data into the HARQ process may be limited to when as many transmissions as the maximum number of transmissions in the corresponding HARQ process have been performed or after receiving ACK information regarding the transmission TB. The process of comparing MCS, rate, and MPR with thresholds may be replaced by a process of comparing the field values ​​of the terminal measured by the base station with thresholds. That is, when the value corresponding to the field value is less than or equal to the threshold, the base station may perform the operation without using the above-described O-HARQ. Furthermore, when NACKs are received continuously, and thus transmission failures accumulate, if the accumulated number exceeds a threshold, the base station can perform operations without using the O-HARQ described above. The processes of the various embodiments of this disclosure described above can utilize a combination of one or more methods and can be used independently of the system operation method.

[0203] A processing scheme for O-HARQ procedures or O-HARQ procedure groups has been described. In addition to the conservatism of O-HARQ procedure groups and transmit-retransmit processes, this disclosure provides a management scheme for O-HARQ procedure groups. O-HARQ procedure groups can be defined in various ways. In various embodiments, the number of HARQ procedures in an O-HARQ procedure group can be configured to a predefined value. In various embodiments, the number of HARQ procedures in an O-HARQ procedure group can be configured to separate configuration values. In various embodiments, the number of HARQ procedures in an O-HARQ procedure can be adaptively configured according to the operation of the base station or terminal.

[0204] The size of an O-HARQ procedure group, i.e., the number of O-HARQ procedures, can be configured. The number of O-HARQ procedure groups can be defined in the configuration method of this disclosure using predefined values ​​or separate configuration values, and once defined in this way, the number of O-HARQ procedure groups can remain unchanged until a new configuration process is executed. Methods for implementing such a configuration method may include always applying predefined fixed values, utilizing a configuration value defined in the base station system and changing that configuration value as necessary, and reflecting the terminal's requests or preferences by exchanging information with the terminal.

[0205] In various embodiments, when using fixed values, the O-HARQ process group may include multiple HARQ processes defined in the steps of designing or implementing the system.

[0206] In various embodiments, when using configuration values ​​or parameters in the base station system, the base station can read the configuration values ​​and apply the obtained configuration values ​​as the size of the O-HARQ procedure group or the number of HARQ procedures assigned to the O-HARQ procedure group.

[0207] In various embodiments, the method of reflecting a terminal's requests or preferences by exchanging information with the terminal can determine the number of HARQ procedures allocated to the O-HARQ procedure group based on messages according to a standard configuration. According to embodiments, the terminal can send a message to the base station indicating a preferred number of O-HARQ procedures (e.g., a UE capability information message, a UE information response message). The base station can then use a configuration message from the terminal to indicate the number of HARQ procedures allocated to the O-HARQ procedure group. The configuration message can include information about whether to implement operations according to embodiments of this disclosure (i.e., opportunity-based HARQ technology), or information about the number of HARQ procedures applied in that embodiment. The configuration associated with the O-HARQ procedures is shared between the base station and the terminal, allowing the base station to perform operations according to opportunity-based HARQ technology with corresponding configurations (configuration of the O-HARQ procedure group, number of O-HARQ procedures). In this case, the configuration message can be a Radio Resource Control (RRC) message exchanged between the base station and the terminal.

[0208] The indicator indicating the number of HARQ procedures applying the above embodiments of this disclosure can be an indirect element, which indicates not only the number of HARQ procedures as expressed in the indicated application, but also the scope of the application of the embodiments of this disclosure. The indirect element can control the size of the O-HARQ procedure group or the number of HARQ procedures allocated to the O-HARQ procedure group. Furthermore, messages configured by the standard as described above can include indicators for determining whether embodiments of this disclosure are applied directly or indirectly to downlink transmissions to the corresponding terminal.

[0209] A method for adaptively managing O-HARQ process groups can be provided to reduce the burden caused by PDCCH conservatism in the application of O-HARQ process groups and to optimize the provision of HARQ combination gain opportunities for O-HARQ process groups. The method for adaptively managing O-HARQ process groups may include adaptively changing the size of the O-HARQ process group or the number of HARQ processes allocated to the O-HARQ process group from a predefined or configured minimum to a maximum value. In this case, the minimum and maximum values ​​may be values ​​fixed and used in advance during the design or implementation of the system, or values ​​configured according to system operation, or values ​​configured by exchanging information with the terminal, similar to the methods described above for configuring the size of the O-HARQ process group or the number of HARQ processes allocated to the O-HARQ process group. Furthermore, the values ​​obtained by exchanging information with the terminal may be direct quantities indicating explicit quantities, or they may be messages including information in a corresponding indirect form (e.g., parameters as the basis for determining the number of O-HARQ processes).

[0210] The following describes an example of configuring a group of O-HARQ procedures between a base station and a terminal, comprising P O-HARQ procedures out of a total of N HARQ procedures. In addition to the P O-HARQ procedures (here, Q equals NP), the base station may also operate Q HARQ procedures (i.e., feedback-based HARQ procedures). According to an embodiment, the O-HARQ procedures are HARQ procedures that apply HARQ technology (opportunity-based HARQ technology) to prevent transmission delays due to a shortage of HARQ procedures, and the base station can transmit new data based on the corresponding HARQ procedure even when no feedback is received regarding the data transmitted in the corresponding HARQ procedure.

[0211] Figure 11 This is a flowchart illustrating example operations of a base station for performing a transmission process for each HARQ procedure, according to various embodiments. The base station is composed of... Figure 1a and Figure 1b Base station 110 is shown.

[0212] Reference Figure 11 In step 1101, the base station can detect whether additional transmission opportunities are needed. Here, additional transmission opportunities refer to the process of acquiring a new TB during the corresponding HARQ process. Figure 5 and Figure 6 The base station can determine whether feedback information for all HARQ processes has not been received. If no feedback information is received, the base station can determine that additional transmission opportunities are needed. Furthermore, according to an embodiment, the base station can determine whether there is a shortage of HARQ processes due to transmission delays in feedback information based on the difference in the parameter set (numerology) between two or more cells configured with CA, or the backhaul delay value between cells configured with CA / DC. When the difference in the parameter set or backhaul delay value is greater than or equal to a threshold, the base station can determine that additional transmission opportunities are needed. Additionally, according to an embodiment, when configuring CA using carriers FR1 and FR2, the base station can predict transmission delays and determine that additional transmission opportunities are needed.

[0213] When an additional transmission opportunity is needed, the base station can perform operation 1103. The base station can perform the operation according to the HARQ technique based on the transmission opportunity. When no additional transmission opportunity is needed, the base station can perform operation 1109. The base station can perform the operation according to the existing HARQ technique.

[0214] In 1103, the base station can identify opportunistic HARQ processes (O-HARQ processes). Even if no feedback information is received regarding each of the currently ongoing HARQ processes, the base station can stop waiting.

[0215] In step 1105, the base station can perform data transmission based on the opportunistic HARQ procedure. The base station can send data based on mapping information. Mapping information can include the relationship between the HARQ procedure ID and the data (PDU or SDU) already sent in the corresponding HARQ procedure. The base station can store the relationship between the identified O-HARQ procedure and the data already sent, and can insert new data regarding the O-HARQ procedure. The relationship between data and the O-HARQ procedure may have already been inserted when the corresponding data is inserted from a higher layer into the corresponding O-HARQ procedure. The base station can send new data based on the O-HARQ procedure. Here, from the terminal's perspective, the new data is new data, and the base station can switch NDI and send this data. On the other hand, from the base station's perspective, the new data may or may not be new data. When an ACK for data in another HARQ procedure is received, new data can be reconfigured based on the data payload that the base station truly intends to send. When a NACK for data in another HARQ procedure is received, new data can be configured to retransmit the corresponding data.

[0216] In step 1107, the base station can execute a retransmission management process for already transmitted data. Since the data transmitted in step 1105 based on the HARQ-based data transmission process is not managed according to the completion of the HARQ process, the base station can execute a separate retransmission management process. The base station can update the mapping information.

[0217] At 1109, the base station can perform data transmission based on a HARQ procedure. Data transmission based on a HARQ procedure refers to data transmission performed according to feedback information (indicating at least one of ACK, NACK, or DTX) regarding data already transmitted in the corresponding HARQ procedure ID. The base station can transmit data configured using information obtained when determining additional transmission opportunities in step 1101 (e.g., ACK feedback, NACK feedback, or information indicating that the number of retransmissions exceeds a maximum value). For example, when the feedback information indicates ACK, the base station can transmit newly configured data. The NDI can be switched, and the RV can be initialized. For example, when the feedback information indicates NACK / DTX, the base station can transmit data configured for retransmission. The NDI can be switched, and the RV (e.g., RV2) can be changed.

[0218] Figure 11The process of determining whether an additional transmission opportunity is needed in step 1001 is shown prior to step 1003, but embodiments of this disclosure are not limited thereto. Depending on a pre-configured HARQ process sequence, the base station may skip step 1001 and instead execute steps 1103 through 1107, or it may execute step 1109.

[0219] According to various embodiments, the entity managing the O-HARQ process group (hereinafter referred to as the base station) can refer to the PDCCH allocation failure rate and timely ACK / NACK information regarding HARQ processes within the O-HARQ process group to adaptively change the size of the O-HARQ process group or the number of HARQ processes allocated to the O-HARQ process group. In this case, the PDCCH allocation failure rate is an additional value when the base station cannot schedule a terminal due to a shortage of PDCCH resources. In this case, the timely ACK / NACK information regarding HARQ processes in the O-HARQ process group is information indicating the number or rate at which HARQ processes in the O-HARQ process group do not follow the transmission process according to embodiments of this disclosure, and after receiving ACK / NACK information regarding the first transmitted data, the second transmitted data is inserted into the HARQ process. The PDCCH allocation failure rate may be information used to identify whether embodiments of this disclosure regarding PDCCH conservatism result in a shortage of radio control resources, and the timely ACK / NACK information regarding HARQ processes in the O-HARQ process group is recorded information about how many transmission and retransmission processes of this disclosure are required. In the following text, it will be through Figure 12a and 12b This describes the operation flow of a base station used to adaptively configure the O-HARQ process based on the above information.

[0220] Figure 12a This is a flowchart illustrating example operations of a base station for adaptively configuring an O-HARQ process group according to various embodiments. The base station is composed of... Figure 1a and Figure 1b Base station 110 is shown. The base station is an example of an entity used to manage O-HARQ process groups, and when the entity used to manage O-HARQ process groups is configured as a separate node from the base station, the corresponding entity can perform the operations described below. Figure 12a The process of adding the O-HARQ procedure will be described in the following section.

[0221] Reference Figure 12a In step 1201, the base station can determine if the number of O-HARQ procedures is less than the maximum value. If the number of O-HARQ procedures is less than the maximum value, the base station can execute a process to add O-HARQ procedures. The base station can then execute step 1203. If the number of O-HARQ procedures is not less than the maximum value, the base station can terminate the process. Figure 12a The process.

[0222] In step 1203, the base station can determine whether the conditions for adding an O-HARQ procedure are met. When it is determined that the PDCCH allocation failure rate is maintained at a preset specific value, or the value corresponding to the number or ratio of timely ACK / NACK events for HARQ procedures in the O-HARQ procedure group is maintained at a predetermined value, the base station adaptively managing the O-HARQ procedure group can increase the size of the O-HARQ procedure group or the number of HARQ procedures allocated to the O-HARQ procedure group. When both of the above conditions are met simultaneously, or only one of the two conditions is met, the corresponding operation can be performed. Alternatively, only one condition can be checked from the outset, and the number of HARQ procedures allocated to the O-HARQ procedure group can be increased. A low PDCCH failure rate can refer to, for example... Figure 10a and Figure 10b The scenario shown is unlikely to occur, and the probability of transmission delay due to a shortage of HARQ procedures is high, so the ACK / NACK arrival rate within the defined time may be low. When the above conditions are met, the base station can execute step 1205. When the above conditions are not met, the base station can terminate the process. Figure 12a The process.

[0223] In 1205, the base station can identify O-HARQ procedures. The base station can identify O-HARQ procedures from existing HARQ procedures (HARQ procedures of Q number) to apply opportunity-based HARQ procedure technology. When the size of the O-HARQ procedure group or the number of HARQ procedures allocated to the O-HARQ procedure group is less than the defined or configured maximum value, the base station can first select HARQ procedures to add.

[0224] In step 1207, the base station can perform conservative processing for the selected HARQ procedure. Conservative processing refers to signal processing performed to allow the PDCCH to be transmitted stably on the channel. The selected HARQ procedure first applies the PDCCH conservative process to the HARQ procedure. For example, the base station can allocate high power to the selected HARQ procedure and can transmit control information for the PDCCH and data for the PSDCH. Furthermore, for example, the base station can perform conservative processing for the selected HARQ procedure to achieve a low transmission rate.

[0225] At step 1209, the base station can determine whether feedback information regarding the data for the selected HARQ procedure has been received. The feedback information can indicate an ACK or NACK for the data related to the HARQ procedure. When feedback information is received, the base station can proceed to step 1211.

[0226] In step 1211, the base station can include the HARQ procedure identified in step 1205 into the O-HARQ procedure group. Upon receiving the ACK / NACK information for the corresponding HARQ procedure, the base station can formally configure the corresponding HARQ procedure to belong to the O-HARQ procedure group. Subsequently, when an O-HARQ procedure is needed (e.g., ...), Figure 11 In step 1101), the base station can perform the transmission process according to the O-HARQ process of the above embodiments of the present disclosure.

[0227] Figure 12a Steps 1207 to 1209 are operations used to configure a stable HARQ process in order to preemptively resolve issues caused by... Figure 10a and Figure 10b The problem arises from the loss of the PDCCH, but in various embodiments, the corresponding operation may not be performed. For example, a process that adds an O-HARQ procedure based on whether the condition of step 1203 is met without conservative processing may be included in embodiments of this disclosure.

[0228] Figure 12b This is a flowchart illustrating example operations of a base station for adaptively configuring an O-HARQ process group according to various embodiments. The base station is composed of... Figure 1a and Figure 1b Base station 110 is shown. The base station is an example of an entity used to manage the O-HARQ process group, and when the entity managing the O-HARQ process group is configured to be a node separate from the base station, the corresponding entity can perform the operations described below. Figure 12b The process for removing the O-HARQ procedure is shown.

[0229] Reference Figure 12b In step 1251, the base station can determine whether the number of O-HARQ procedures is greater than a minimum value. When the number of O-HARQ procedures is greater than the minimum value, the base station can execute a process to remove the O-HARQ procedures. The base station can then execute operation 1253. When the number of O-HARQ procedures is not greater than the minimum value, the base station can terminate the process. Figure 12b The process.

[0230] In step 1253, the base station can determine whether the conditions for removing the O-HARQ process are met. When it is determined that the PDCCH allocation failure rate remains greater than or equal to a preset specific value, or the value corresponding to the number or ratio of timely ACK / NACK events for HARQ processes in the O-HARQ process group remains greater than or equal to a predetermined value, the base station adaptively managing the O-HARQ process group can reduce the size of the O-HARQ process group or the number of HARQ processes allocated to the O-HARQ process group. When both of the above conditions are met simultaneously, or only one of the two conditions is met, the corresponding operation can be performed. Alternatively, only one condition can be checked from the beginning, and the number of HARQ processes allocated to the O-HARQ process group can be reduced. When the above conditions are met, the base station can execute step 1255. When the above conditions are not met, the base station can terminate the process. Figure 12b The process.

[0231] At 1255, the base station can identify O-HARQ procedures. The base station can identify normal HARQ procedures within O-HARQ procedures (P-number HARQ procedures) to apply normal HARQ procedure techniques.

[0232] When the size of an O-HARQ procedure group or the number of HARQ procedures allocated to an O-HARQ procedure group exceeds a defined or configured minimum, the base station can select a HARQ procedure to remove from the O-HARQ procedure group and configure the corresponding HARQ procedure to operate according to the existing HARQ operation process. Existing HARQ operations can refer to waiting without inserting new data in the corresponding HARQ procedure until feedback information is received, or generating new data based on the feedback information (when the feedback information is ACK) or retransmitting data (when the feedback information is NACK) and transmitting them when feedback information is received.

[0233] exist Figure 12a and Figure 12b In the process of identifying one or more conditions (e.g., steps 1203, 1253), the expression "maintained as" may imply that a particular state is maintained continuously or within a defined range, and may imply that the time during which the state is maintained or the resulting value is greater than or equal to a threshold or exceeds a threshold.

[0234] Regarding the above Figure 12a and Figure 12b The series of processes described in this disclosure can be applied together in embodiments. That is, Figure 12a Some operations on sequence diagrams can be combined Figure 12b Some operations on the sequence diagram are performed. According to an embodiment, when the conditions are not met... Figure 12a When the conditions of step 1201 or step 1203 are met, the base station can be configured to perform... Figure 12b Step 1251. Furthermore, according to an embodiment, when the following conditions are not met... Figure 12b When the conditions of step 1251 or step 1253 are met, the base station can be configured to perform... Figure 12a Step 1201.

[0235] The conditions for adding or removing O-HARQ procedures are determined based on the PDCCH allocation failure rate and the timely ACK / NACK rate. When the target number of O-HARQ procedures in an O-HARQ procedure group (the number of O-HARQ procedures) is less than a given maximum value (MAX_O-HARQ) for O-HARQ procedures, the base station can determine whether the PDCCH allocation failure rate and the timely ACK / NACK rate are less than a threshold. This might mean, for example, that there are sufficient PDCCH resources, but the ratio of procedures in the O-HARQ procedure group used for existing HARQ operations is low due to latency. In this case, the aforementioned operation process can be performed to increase the number of O-HARQ procedures. Additionally, when the current environment does not meet the conditions for increasing the number of O-HARQ procedures, the base station can identify whether the conditions for removing O-HARQ procedures (i.e., reducing them) are met. This operation can be performed only when the number of target processes in the O-HARQ process group (the number of O-HARQ processes) is greater than the given minimum number of O-HARQ processes (MIN_O-HARQ), and the operation process of reducing the number of O-HARQ processes can be performed only when the PDCCH allocation failure rate or the timely ACK / NACK rate information is greater than the threshold.

[0236] pass Figure 12a and Figure 12b The O-HARQ process group can be adaptively configured. The base station can adaptively operate the O-HARQ process based on the configuration. In various embodiments, the base station and terminal can reconfigure the O-HARQ process via separate configuration messages (e.g., RRC messages). The base station can configure and manage the O-HARQ process periodically or intermittently based on the occurrence of events. In various embodiments, in addition to configuration messages, the base station can manage the O-HARQ process via additional control signaling. The O-HARQ process can be individually configured in an activation / deactivation form via control signaling such as MAC CE or DCI. For example, when a HARQ process ID is indicated and sent in the MAC CE, the corresponding HARQ process can be activated as an O-HARQ process. The activated O-HARQ process can apply a transmission opportunity-based HARQ process (…). Figures 5 to 7 Furthermore, for example, when a HARQ procedure ID is indicated and sent in MACCE, the corresponding HARQ procedure can be deactivated into an O-HARQ procedure. The deactivated HARQ procedure can then be used with a normal HARQ process. Figures 4a to 4c).

[0237] According to various embodiments of this disclosure, depending on the given situation, the HARQ method used as a retransmission process in a wireless communication system can be adaptively operated to obtain bit combinations according to the HARQ method, or follow a separate retransmission process by sacrificing the corresponding gain. A separate retransmission process refers to a process that independently performs a new transmission or retransmission using HARQ process IDs and mapping information included in the base station. [This has been achieved through...] Figure 6 and Figure 7 The retransmission process is described.

[0238] According to various embodiments of this disclosure, the base station can obtain the HARQ gain (gain obtained by bit combination) of the terminal without mobilely utilizing HARQ in a CA environment, and in this case, different retransmission methods can be used to adaptively perform the retransmission process according to the wireless environment between the base station and the terminal, and retransmission can be performed adaptively. This has been achieved through... Figure 6 and Figure 7 The retransmission process is described.

[0239] For example, according to various embodiments of this disclosure, a base station can segment information bits for retransmission and distribute them to different PDUs to transmit the information bits.

[0240] According to various embodiments of this disclosure, through HARQ process management techniques, a base station can fixedly or adaptively divide and manage HARQ processes that perform transmissions by mixing transmission processes that only perform HARQ operations (feedback-based HARQ processes) and separate retransmission processes (transmission opportunity-based HARQ processes).

[0241] pass Figures 4a to 12b The operation of sending new data or rediscovering existing data during the HARQ process has been described. In this case, as an example, TB has been described as the unit of data transmitted. However, various embodiments of this disclosure may include transmission and retransmission in units of code blocks (CBs) or code block groups (CBGs). According to an embodiment, when a transmission opportunity-based HARQ process is applied to a terminal configured with CBG retransmission, the base station can indicate that the soft buffer is empty via a CBG clear indicator.

[0242] Figure 13 This is a block diagram illustrating an example configuration of a base station in a wireless communication system according to various embodiments. The term "unit" or any term ending with the suffix "device" or "and" as used in the following description refers to a unit that processes at least one function or operation and can be implemented by hardware, software, or a combination of hardware and software.

[0243] Reference Figure 13The base station may include a wireless communication unit 1301, a backhaul communication unit 1303, a storage device 1305, and a controller 1307.

[0244] The wireless communication unit 1301 performs the function of transmitting and receiving signals via a wireless channel. For example, the wireless communication unit 1301 can perform the function of converting between baseband signals and bitstreams according to the physical layer standard of the system. For example, when transmitting data, the wireless communication unit 1301 can generate complex symbols by encoding and modulating the transmitted bitstream. In addition, when receiving data, the wireless communication unit 1301 can recover the received bitstream by demodulating and decoding the baseband signal. Furthermore, the wireless communication unit 1301 can upconvert the baseband signal to a radio frequency (RF) band signal, and then transmit the signal via an antenna, and can downconvert the RF band signal received via the antenna back to a baseband signal.

[0245] To achieve this, the wireless communication unit 1301 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a digital-to-analog converter (DAC), an analog-to-digital converter (ADC), etc. Furthermore, the wireless communication unit 1301 may include multiple transmit and receive paths. Additionally, the wireless communication unit 1301 may include at least one antenna array comprising multiple antenna elements. In terms of hardware, the wireless communication unit 1301 may be configured with digital and analog units, and the analog units may be configured with multiple sub-units according to operating power, operating frequency, etc. According to an embodiment, the wireless communication unit 1301 may include a unit for beamforming, i.e., a beamforming unit. For example, the wireless communication unit 1301 may include a massive MIMO unit (MMU) for beamforming.

[0246] The wireless communication unit 1301 can transmit and receive signals. To achieve this, the wireless communication unit 1301 may include at least one transceiver. For example, the wireless communication unit 1301 can transmit synchronization signals, reference signals, system information, messages, control information, or data, etc. Furthermore, the wireless communication unit 1301 can perform beamforming. The wireless communication unit 1301 can apply beamforming weights to the signal to be transmitted or received to provide directionality according to the configuration of the controller 1307. According to an embodiment, the wireless communication unit 1301 can generate a baseband signal based on the scheduling results and the results of calculating the transmission power. Furthermore, the RF unit in the wireless communication unit 1301 can transmit the generated signal via an antenna.

[0247] The wireless communication unit 1301 can transmit and receive signals as described above. Therefore, all or part of the wireless communication unit 1301 can be referred to as a "transmitter," a "receiver," or a "transceiver." Furthermore, in the following description, transmission and reception via a wireless channel can be interpreted as including the processing of the wireless communication unit 1301 as described above.

[0248] The backhaul communication unit 1303 provides an interface for communicating with other nodes in the network. That is, the backhaul communication unit 1303 can convert a bit stream to be sent from the base station to another node (e.g., another access node, another base station, a higher node, the core network, etc.) into a physical signal, and can convert a physical signal sent from another node into a bit stream.

[0249] Storage device 1305 can store data, such as basic programs, applications, and configuration information for base station operation. Storage device 1305 may include memory. Storage device 1305 may be configured with volatile memory, non-volatile memory, or a combination of volatile and non-volatile memory. Furthermore, storage device 1305 provides stored data upon request from controller 1307. According to an embodiment, storage device 1305 may store mapping information defining the relationship between HARQ process IDs and RLC PDU / MACSDU or MAC PDU / TB. Furthermore, according to an embodiment, in addition to the data ID, the mapping information may also include actual data. The actual data may be stored in a buffer of storage device 1305. Furthermore, according to an embodiment, the mapping information may include time information related to the mapping time or the time when a new TB is inserted into the HARQ process.

[0250] Controller 1307 controls the overall operation of the base station. For example, controller 1307 can send and receive signals via wireless communication unit 1301 or backhaul communication unit 1303. Furthermore, controller 1307 can write data to and read data from storage device 1305. Additionally, controller 1307 can perform the functions of the protocol stack required by the communication standard. To achieve this, controller 1307 may include at least one processor. According to various embodiments, controller 1307 can control the base station to perform operations according to the various embodiments described above. According to various embodiments, the base station can send data for a new TB based on the HARQ process before receiving feedback information about the HARQ process. That is, the base station can insert a new TB into the HARQ process independently of feedback information about the HARQ process. Furthermore, according to embodiments, the base station can utilize previously sent data based on mapping information in storage device 1305. That is, even if the HARQ process is different, the base station can configure data corresponding to the TB of the received NACK information. From the terminal's perspective, the data can be indicated as new data (e.g., NDI is switched, RV is initialized), but the base station can perform retransmission.

[0251] Figure 13 The configuration of base station 110 shown is merely an example of a base station, and examples of base stations implementing the various embodiments of this disclosure are not limited to this. Figure 13 The configuration shown is as described. For example, according to various embodiments, some configurations can be added, deleted, changed, etc.

[0252] exist Figure 13 In this disclosure, a base station is shown as an entity, but the present disclosure is not limited thereto. Base stations according to various embodiments of the present disclosure can be implemented to form access networks that are not only monolithically deployed but also distributed. According to embodiments, base stations can be classified into central units (CUs) and digital units (DUs), and CUs can be implemented to perform upper-layer functions (e.g., Packet Data Convergence Protocol (PDCP) RRC), while DUs can be implemented to perform lower-layer functions (e.g., Media Access Control (MAC), Physical (PHY)).

[0253] Figure 14 This is a block diagram illustrating an example configuration of a terminal in a wireless communication system according to various embodiments. The term "unit" or any term ending with the suffix "device" or "and" as used in the following description refers to a unit that processes at least one function or operation and can be implemented by hardware, software, or a combination of hardware and software.

[0254] refer to Figure 14 The terminal may include a communication unit 1401, a storage device 1403, and a controller 1405.

[0255] Communication unit 1401 performs the function of transmitting and receiving signals via a wireless channel. For example, communication unit 1401 can perform the function of converting between baseband signals and bitstreams according to the physical layer standard of the system. For example, when transmitting data, communication unit 1401 can generate complex symbols by encoding and modulating the transmitted bitstream. In addition, when receiving data, communication unit 1401 can recover the received bitstream by demodulating and decoding the baseband signal. Furthermore, communication unit 1401 can upconvert the baseband signal to an RF band signal and then transmit the signal via an antenna, and can downconvert the RF band signal received via the antenna back to a baseband signal. For example, communication unit 1401 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, etc.

[0256] Furthermore, communication unit 1401 may include multiple transmit and receive paths. Additionally, communication unit 1401 may include antenna elements. Communication unit 1401 may include at least one antenna array, which includes multiple antenna elements. In terms of hardware, communication unit 1401 may be configured with digital and analog circuitry (e.g., radio frequency integrated circuits (RFICs)). Here, the digital and analog circuitry may be implemented in a single package. Furthermore, communication unit 1401 may include multiple RF chains. Communication unit 1401 may perform beamforming. Communication unit 1401 may apply beamforming weights to signals to be transmitted or received in order to provide directionality according to the configuration of controller 1405.

[0257] Furthermore, the communication unit 1401 can transmit and receive signals. To achieve this, the communication unit 1401 may include at least one transceiver. The communication unit 1401 can receive downlink signals. Downlink signals may include synchronization signals (SS), reference signals (RS) (e.g., cell-specific reference signals (CRS), demodulation (DM)-RS), system information (e.g., MIB, SIB, residual system information (RMSI), other system information (OSI)), configuration messages, control information, or downlink data. Additionally, the communication unit 1401 can transmit uplink signals. Uplink signals may include random access related signals (e.g., random access preamble (RAP)) (or message 1 (Msg1), message 3 (Msg3)), reference signals (e.g., sounding reference signals (SRS), DM-RS), or buffer status reports (BSR), etc.

[0258] For example, communication unit 1401 may include an RF processing unit and a baseband processing unit. The RF processing unit can perform functions such as transmitting and receiving signals via a wireless channel, including signal band conversion and amplification. For example, the RF processing unit can up-convert a baseband signal provided by the baseband processing unit into an RF band signal, then transmit the signal via an antenna, and down-convert an RF band signal received via the antenna back into a baseband signal. For example, the RF processing unit may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a digital-to-analog converter (DAC), an analog-to-digital converter (ADC), etc. The terminal may include one antenna, but the terminal may also include multiple antennas. Furthermore, the RF processing unit may include multiple RF chains. Additionally, the RF processing unit can perform beamforming. For beamforming, the RF processing unit can adjust the phase and magnitude of each of the signals transmitted and received through multiple antennas or antenna elements.

[0259] The baseband processing unit can perform conversion functions between baseband signals and bitstreams according to the system's physical layer standards. For example, when transmitting data, the baseband processing unit can generate complex symbols by encoding and modulating the transmission bitstream. Furthermore, when receiving data, the baseband processing unit can recover the received bitstream by demodulating and decoding the baseband signal provided by the RF processing unit. For instance, when transmitting data according to the Orthogonal Frequency Division Multiplexing (OFDM) method, the baseband processing unit can generate complex symbols by encoding and modulating the transmission bitstream, map the complex symbols onto subcarriers, and then configure the OFDM symbols using inverse Fast Fourier Transform (IFFT) operations and cyclic prefix (CP) insertion. Similarly, when receiving data, the baseband processing unit can divide the baseband signal provided by the RF processing unit into units of OFDM symbols, recover the signals mapped onto subcarriers using Fast Fourier Transform (FFT) operations, and then recover the received bitstream through demodulation and decoding.

[0260] Communication unit 1401 can transmit and receive signals as described above. Therefore, all or part of communication unit 1401 can be referred to as a "transmitter," a "receiver," or a "transceiver." Furthermore, communication unit 1401 can include multiple communication modules to support a variety of different radio access technologies. Additionally, communication unit 1401 can include different communication modules to handle signals in different frequency bands. For example, different radio access technologies can include wireless local area networks (LANs) (e.g., IEEE 802.1x), cellular networks (e.g., Long Term Evolution (LTE), New Radio (NR)), etc. Furthermore, different frequency bands can include ultra-high frequency (SHF) bands (e.g., 2.5 GHz, 5 GHz) bands, millimeter wave (e.g., 60 GHz) bands. Furthermore, communication unit 1401 can use the same radio access technology (e.g., unlicensed band for licensed auxiliary access (LAA), citizen broadband radio service (CBRS) (e.g., 3.5 GHz)) in different frequency bands.

[0261] Storage device 1403 can store data, such as basic programs, application programs, and configuration information for terminal operation. Storage device 1403 can be configured with volatile memory, non-volatile memory, or a combination of volatile and non-volatile memory. Furthermore, storage device 1403 can store data, such as basic programs, application programs, and configuration information for terminal operation.

[0262] Controller 1405 controls the overall operation of the terminal. For example, controller 1405 can send and receive signals via communication unit 1401. Furthermore, controller 1405 can write data to and read data from storage device 1403. Additionally, controller 1405 can perform the functions of the protocol stack required by the communication standard. To achieve this, controller 1405 may include at least one processor. Controller 1405 may include at least one processor or microprocessor, or may be part of a processor. Additionally, communication unit 1401 and a portion of controller 1405 may be referred to as a communication processor (CP). Controller 1405 may include various modules to perform communication. According to various embodiments, controller 1405 can control the terminal to perform operations according to various embodiments, which will be described below.

[0263] Controller 1405 controls the overall operation of the terminal. For example, controller 1405 can send and receive signals via communication unit 1401. Furthermore, controller 1405 can write data to and read data from storage device 1403. To achieve this, controller 1405 may include at least one processor. For example, controller 1405 may include a communication processor (CP) that performs control of communication, and a higher-level application processor (AP) that controls applications. According to embodiments of this disclosure, controller 1405 may include a multi-connection processing unit to perform processing for operation in a multi-connection mode. For example, controller 1405 can control the terminal to perform operations according to the various embodiments described above. According to various embodiments, controller 1405 can individually execute HARQ process steps based on the number of O-HARQ feedbacks. Controller 1405 can identify the HARQ process number, NDI, RV, and TBS included in the HARQ information. Controller 1405 can decode data (PDSCH) and can feed its results back to the terminal.

[0264] According to various embodiments of this disclosure, depending on the given circumstances, the HARQ method used as a retransmission process in a wireless communication system can be adaptively operated to obtain bit combinations according to the HARQ method, or to follow separate retransmission processes by sacrificing corresponding gains. Specifically, additional processing (e.g., low data rate, low MCS level, segmentation, etc.) can be performed to transmit more stably during retransmissions. Furthermore, the O-HARQ process can be adaptively selected from all HARQ processes and can be operated to preemptively mitigate problems that may arise when an existing HARQ process is not followed.

[0265] The methods based on the claims or embodiments disclosed in this disclosure can be implemented in hardware, software, or a combination of both.

[0266] When implemented in software, a computer-readable storage medium may be provided for storing one or more programs (software modules). The one or more programs stored in the computer-readable storage medium are configured to be executed by one or more processors in an electronic device. The one or more programs include instructions for allowing the electronic device to perform methods based on the claims or embodiments disclosed in this disclosure.

[0267] The program (software module or software) can be stored in random access memory, including non-volatile memory such as flash memory, read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), disk storage devices, optical disc ROM (CD-ROM), digital versatile disc (DVD), or other forms of optical storage devices, as well as magnetic tape. Alternatively, the program can be stored in memory, which is configured with all or some of these storage media. Furthermore, there can be multiple configured memories.

[0268] Furthermore, the program can be stored in an attachable storage device that can be accessed by the electronic device via a communication network such as the Internet, intranet, local area network (LAN), wide area network (WLAN), or storage area network (SAN), or a communication network configured through a combination of networks. The storage device can access the device executing embodiments of this disclosure via an external port. Additionally, an attached storage device on the communication network can access the device executing embodiments of this disclosure.

[0269] In the above exemplary embodiments of this disclosure, the elements included in this disclosure are expressed in singular or plural form according to specific embodiments. However, for ease of explanation, the singular or plural form may be appropriately selected according to the suggested circumstances, and this disclosure is not limited to a single element or multiple elements. Elements expressed in plural form may be configured in singular form, or elements expressed in singular form may be configured in plural form.

[0270] While specific embodiments have been described in the detailed description of this disclosure, those skilled in the art will understand that various changes can be made thereto without departing from the spirit and scope of this disclosure. Therefore, the scope of this disclosure should not be limited by the described embodiments, but rather by the appended claims or their equivalents.

Claims

1. A method of a base station in a wireless communication system, the method comprising: transmitting first data based on a first hybrid automatic request (HARQ) process; transmitting second data based on the first HARQ process; generating third data based on a reception result of the first data after transmitting the second data; and transmitting the third data based on a second HARQ process, wherein the transmitting of the second data comprises storing mapping information about a relationship between the first HARQ process and the first data at a medium access control (MAC) layer, and wherein the mapping information comprises an identifier of the first HARQ process, an identifier about the first data, a packet of the first data, and timing information about a time when a protocol data unit (PDU) or a service data unit (SDU) is delivered through a corresponding HARQ process ID. The generating of the third data comprises:

2. The method of claim 1, wherein, identifying whether the reception result of the first data indicates a negative acknowledgement (NACK); identifying the first data from the mapping information based on the reception result of the first data indicating the NACK; and generating the third data based on the identified first data. The packet comprises a radio link control (RLC) PDU, and 3. The method of claim 1, wherein, wherein the identifier about the first data is a sequence number (SN). The packet comprises a radio link control (RLC) SDU, and 4. The method of claim 1, wherein, wherein the identifier about the first data comprises an identifier (ID) for indicating the RLC SDU. The third data is transmitted with a transport block size (TBS) smaller than that of the first data or with a lower modulation and coding scheme (MCS) level.

5. The method of claim 1, wherein, The transmitting of the second data comprises:

6. The method of claim 1, wherein, determining whether there is a HARQ process in which a transmission process accompanying a HARQ process operation is not in progress among all HARQ processes; identifying the first HARQ process based on the HARQ process in which the transmission process accompanying the HARQ process operation is not in progress among all HARQ processes; and transmitting the second data based on the identified first HARQ process. 7.A base station in a wireless communication system, the base station comprising: at least one transceiver; and at least one processor coupled with the at least one transceiver, wherein the at least one processor is configured to: transmit first data based on a first hybrid automatic request (HARQ) process; transmit second data based on the first HARQ process; generate third data based on a reception result of the first data after transmitting the second data; and transmit the third data based on a second HARQ process, wherein, to transmit the second data, the at least one processor is configured to store mapping information about a relationship between the first HARQ process and the first data at a medium access control (MAC) layer, and wherein the mapping information comprises an identifier of the first HARQ process, an identifier about the first data, a packet of the first data, and timing information about a time when a protocol data unit (PDU) or a service data unit (SDU) is delivered through a corresponding HARQ process ID. To generate the third data, the at least one processor is configured to: identify whether the reception result of the first data indicates a negative acknowledgement (NACK); 8. The base station of claim 7, wherein, ​ ​ identify the first data from the mapping information based on the reception result of the first data indicating a NACK; and generate third data based on the identified first data.

9. The base station of claim 7, wherein, The packet includes a radio link control (RLC) protocol data unit (PDU), and The identifier about the first data is a sequence number (SN).

10. The base station of claim 7, wherein, The packet includes a radio link control (RLC) service data unit (SDU), and The identifier about the first data includes an identifier (ID) for indicating the RLC SDU.

11. The base station of claim 7, wherein, The third data is transmitted with a transport block size (TBS) smaller than that of the first data or a modulation and coding scheme (MCS) level lower than that of the first data.

12. The base station of claim 7, wherein, To transmit the second data, the at least one processor is configured to: determine whether there is a HARQ process in which a transmission process accompanying a HARQ process operation is not ongoing among all HARQ processes; identify a first HARQ process based on the HARQ process in which the transmission process accompanying the HARQ process operation is not ongoing among all HARQ processes; and control the at least one transceiver to transmit the second data based on the identified first HARQ process. To transmit the second data, the at least one processor is configured to control the at least one transceiver to transmit the second data based on not obtaining a reception result of the first data.

13. The base station of claim 7, wherein, ​

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