Patent Publication Number: US-2023145930-A1

Title: Method and device for transmitting and receiving wireless signal in wireless communication system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Application No. PCT/KR2021/010396, filed on Aug. 6, 2021, which claims the benefit of earlier filing date and right of priority to Korean Patent Application Nos. 10-2020-0098739, filed on Aug. 6, 2020, 10-2020-0150410, filed on Nov. 11, 2020, and 10-2021-0006332, filed on Jan. 15, 2021, the contents of which are hereby incorporated by reference herein in their entireties. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a wireless communication system, and more particularly, to a method and apparatus for transmitting and receiving a wireless signal. 
     BACKGROUND 
     Wireless communication systems have been widely deployed to provide various types of communication services such as voice or data. In general, a wireless communication system is a multiple access system that supports communication of multiple users by sharing available system resources (a bandwidth, transmission power, etc.). Examples of multiple access systems include a code division multiple access (CDMA) system, a frequency division multiple access (FDMA) system, a time division multiple access (TDMA) system, an orthogonal frequency division multiple access (OFDMA) system, and a single carrier frequency division multiple access (SC-FDMA) system. 
     SUMMARY 
     An aspect of the present disclosure is to provide a method and apparatus for efficiently transmitting and receiving a wireless signal. 
     Another object of the present disclosure is to provide an improved hybrid automatic repeat request (HARQ) method for solving a latency problem caused by a relatively large round trip time (RTT) in a non-terrestrial network (NTN) environment and apparatus therefor. 
     It will be appreciated by persons skilled in the art that the objects that could be achieved with the present disclosure are not limited to what has been particularly described hereinabove and the above and other objects that the present disclosure could achieve will be more clearly understood from the following detailed description. 
     According to a first aspect of the present disclosure, there is provided a method performed by a user equipment (UE) in a wireless communication system. The method may include: receiving control information for disabling at least one of a plurality of hybrid automatic repeat request (HARQ) processes; receiving a downlink signal based on the control information; and determining whether to perform HARQ feedback for the downlink signal based on a HARQ acknowledgement (HARQ-ACK) codebook determined based on the control information. The HARQ-ACK codebook may be determined based on one or more enabled HARQ processes among the plurality of HARQ processes. 
     According to a second aspect of the present disclosure, there is provided a UE configured to operate in a wireless communication system. The UE may include: at least one radio frequency (RF) unit; at least one processor; and at least one computer memory operably coupled to the at least one processor and configured to, when executed, cause the at least one processor to perform operations. The operations may include: receiving control information for disabling at least one of a plurality of HARQ processes; receiving a downlink signal based on the control information; and determining whether to perform HARQ feedback for the downlink signal based on a HARQ-ACK codebook determined based on the control information. The HARQ-ACK codebook may be determined based on one or more enabled HARQ processes among the plurality of HARQ processes. 
     According to a third aspect of the present disclosure, there is provided an apparatus for a UE. The apparatus may include: at least one processor; and at least one computer memory operably coupled to the at least one processor and configured to, when executed, cause the at least one processor to perform operations. The operations may include: receiving control information for disabling at least one of a plurality of HARQ processes; receiving a downlink signal based on the control information; and determining whether to perform HARQ feedback for the downlink signal based on a HARQ-ACK codebook determined based on the control information. The HARQ-ACK codebook may be determined based on one or more enabled HARQ processes among the plurality of HARQ processes. 
     According to a fourth aspect of the present disclosure, there is provided a computer-readable storage medium comprising at least one computer program configured to, when executed, cause at least one processor to perform operations. The operations may include: receiving control information for disabling at least one of a plurality of HARQ processes; receiving a downlink signal based on the control information; and determining whether to perform HARQ feedback for the downlink signal based on a HARQ-ACK codebook determined based on the control information. The HARQ-ACK codebook may be determined based on one or more enabled HARQ processes among the plurality of HARQ processes. 
     According to a fifth aspect of the present disclosure, there is provided a method performed by a base station in a wireless communication system. The method may include: transmitting control information for disabling at least one of a plurality of HARQ processes; transmitting a downlink signal based on the control information; and receiving HARQ feedback for the downlink signal based on a HARQ-ACK codebook determined based on the control information. The HARQ-ACK codebook may be determined based on one or more enabled HARQ processes among the plurality of HARQ processes. 
     According to a sixth aspect of the present disclosure, there is provided a base station configured to operate in a wireless communication system. The base station may include: at least one RF unit; at least one processor; and at least one computer memory operably coupled to the at least one processor and configured to, when executed, cause the at least one processor to perform operations. The operations may include: transmitting control information for disabling at least one of a plurality of HARQ processes; transmitting a downlink signal based on the control information; and receiving HARQ feedback for the downlink signal based on a HARQ-ACK codebook determined based on the control information. The HARQ-ACK codebook may be determined based on one or more enabled HARQ processes among the plurality of HARQ processes. 
     According to an embodiment, the one or more enabled HARQ processes may include remaining HARQ processes except for the at least one HARQ process disabled based on the control information among the plurality of HARQ processes. 
     According to an embodiment, the plurality of HARQ processes may be configured for each of a plurality of cells configured for the UE, and the HARQ-ACK codebook may be determined based on a cell including the one or more enabled HARQ processes. 
     According to an embodiment, the at least one disabled HARQ process may be excluded from the determination of the HARQ-ACK codebook. 
     According to an embodiment, the UE may be configured to ignore a counter downlink assignment indicator (C-DAI) value in downlink control information (DCI) indicating the at least one disabled HARQ process. 
     According to an embodiment, the HARQ-ACK codebook may include a Type 1 HARQ-ACK codebook, a Type 2 HARQ-ACK codebook, or a Type 3 HARQ-ACK codebook. 
     According to an embodiment, a timing offset for performing the HARQ feedback may be indicated based on a value determined based on a resource index and a value of a specific field value with a fixed size in DCI. 
     According to an embodiment, the resource index may include a specific index of a slot in which a physical downlink control channel (PDCCH) or a physical downlink shared channel (PDSCH) scheduled by the PDCCH is received, a system frame number (SFN), or an index of a control channel element (CCE) in which the PDCCH is received. 
     According to an embodiment, the wireless communication system may include a non-terrestrial network (NTN). 
     According to the present disclosure, a wireless signal may be transmitted and received efficiently in a wireless communication system. 
     According to the present disclosure, it is possible to solve a latency problem caused by a relatively large round trip delay (RTD) in a non-terrestrial network (NTN) environment. 
     According to the present disclosure, when hybrid automatic repeat request (HARQ) feedback is disabled, a HARQ acknowledgement (HARQ-ACK) codebook may be configured efficiently. 
     It will be appreciated by persons skilled in the art that the effects that can be achieved with the present disclosure are not limited to what has been particularly described hereinabove and other advantages of the present disclosure will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this application, illustrate embodiments of the disclosure and together with the description serve to explain the principle of the disclosure. 
         FIG.  1    illustrates physical channels used in a 3rd generation partnership project (3GPP) system as an exemplary wireless communication systems and a general signal transmission method using the same. 
         FIG.  2    illustrates the structure of an NR system to which embodiment(s) are applicable. 
         FIG.  3    illustrates the structure of an NR radio frame to which embodiment(s) are applicable. 
         FIG.  4    illustrates the slot structure of an NR frame to which embodiment(s) are applicable. 
         FIG.  5    is a diagram for explaining a hybrid automatic repeat request acknowledgement (HARQ-ACK) operation. 
         FIG.  6    illustrates a non-terrestrial network (NTN). 
         FIG.  7    illustrates an overview and a scenario of an NTN. 
         FIG.  8    illustrates TA components of the NTN. 
         FIG.  9    is a flowchart illustrating a method for a user equipment (UE) to transmit an uplink (UL) signal in an NTN according to an embodiment. 
         FIG.  10    is a flowchart illustrating a method for a UE to receive a downlink (DL) signal in an NTN according to an embodiment. 
         FIG.  11    is a flowchart illustrating a method for a base station (BS) to receive a UL signal in an NTN according to the above-described embodiment. 
         FIG.  12    is a flowchart illustrating a method for a BS to transmit a DL signal in an NTN according to the above-described embodiment. 
         FIG.  13    is a diagram illustrating a method of identifying a HARQ process based on the lowest control channel element (CCE) index according to a proposed embodiment. 
         FIG.  14    is a flowchart illustrating operations of a UE according to proposed embodiments. 
         FIG.  15    is a flowchart illustrating operations of transmitting and receiving a UL signal between a BS and a UE according to proposed embodiments. 
         FIG.  16    is a flowchart illustrating operations of transmitting and receiving a DL signal between a BS and a UE according to proposed embodiments. 
         FIG.  17    illustrates a communication system applied to the present disclosure. 
         FIG.  18    illustrates wireless devices applicable to the present disclosure. 
         FIG.  19    illustrates another example of a wireless device to which the present disclosure is applied. 
         FIG.  20    illustrates a vehicle or an autonomous driving vehicle applied to the present disclosure. 
         FIG.  21    illustrates a very-small-aperture terminal (VSAT) to which the present disclosure is applied. 
         FIG.  22    illustrates an exemplary integrated access backhaul (IAB) to which the present disclosure is applied. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present disclosure are applicable to a variety of wireless access technologies such as code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), and single carrier frequency division multiple access (SC-FDMA). CDMA can be implemented as a radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA can be implemented as a radio technology such as Global System for Mobile communications (GSM)/General Packet Radio Service (GPRS)/Enhanced Data Rates for GSM Evolution (EDGE). OFDMA can be implemented as a radio technology such as Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wireless Fidelity (Wi-Fi)), IEEE 802.16 (Worldwide interoperability for Microwave Access (WiMAX)), IEEE 802.20, and Evolved UTRA (E-UTRA). UTRA is a part of Universal Mobile Telecommunications System (UMTS). 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) is part of Evolved UMTS (E-UMTS) using E-UTRA, and LTE-Advanced (A) is an evolved version of 3GPP LTE. 3GPP NR (New Radio or New Radio Access Technology) is an evolved version of 3GPP LTE/LTE-A. 
     As more and more communication devices require a larger communication capacity, there is a need for mobile broadband communication enhanced over conventional radio access technology (RAT). In addition, massive machine type communications (MTC) capable of providing a variety of services anywhere and anytime by connecting multiple devices and objects is another important issue to be considered for next generation communications. Communication system design considering services/UEs sensitive to reliability and latency is also under discussion. As such, introduction of new radio access technology considering enhanced mobile broadband communication (eMBB), massive MTC, and ultra-reliable and low latency communication (URLLC) is being discussed. In the present disclosure, for simplicity, this technology will be referred to as NR (New Radio or New RAT). 
     For the sake of clarity, 3GPP NR is mainly described, but the technical idea of the present disclosure is not limited thereto. 
     In a wireless communication system, a user equipment (UE) receives information through downlink (DL) from a base station (BS) and transmit information to the BS through uplink (UL). The information transmitted and received by the BS and the UE includes data and various control information and includes various physical channels according to type/usage of the information transmitted and received by the UE and the BS. 
       FIG.  1    illustrates physical channels used in a 3GPP NR system and a general signal transmission method using the same. 
     When powered on or when a UE initially enters a cell, the UE performs initial cell search involving synchronization with a BS in step S 101 . For initial cell search, the UE receives synchronization signal block (SSB). The SSB includes a primary synchronization signal (PSS), a secondary synchronization signal (SSS), and a physical broadcast channel (PBCH). The UE synchronizes with the BS and acquires information such as a cell Identifier (ID) based on the PSS/SSS. Then the UE may receive broadcast information from the cell on the PBCH. In the meantime, the UE may check a downlink channel status by receiving a downlink reference signal (DL RS) during initial cell search. 
     After initial cell search, the UE may acquire more specific system information by receiving a physical downlink control channel (PDCCH) and receiving a physical downlink shared channel (PDSCH) based on information of the PDCCH in step S 102 . 
     The UE may perform a random access procedure to access the BS in steps S 103  to S 106 . For random access, the UE may transmit a preamble to the BS on a physical random access channel (PRACH) (S 103 ) and receive a response message for preamble on a PDCCH and a PDSCH corresponding to the PDCCH (S 104 ). In the case of contention-based random access, the UE may perform a contention resolution procedure by further transmitting the PRACH (S 105 ) and receiving a PDCCH and a PDSCH corresponding to the PDCCH (S 106 ). 
     After the foregoing procedure, the UE may receive a PDCCH/PDSCH (S 107 ) and transmit a physical uplink shared channel (PUS CH)/physical uplink control channel (PUCCH) (S 108 ), as a general downlink/uplink signal transmission procedure. Control information transmitted from the UE to the BS is referred to as uplink control information (UCI). The UCI includes hybrid automatic repeat and request acknowledgement/negative-acknowledgement (HARQ-ACK/NACK), scheduling request (SR), channel state information (CSI), etc. The CSI includes a channel quality indicator (CQI), a precoding matrix indicator (PMI), a rank indicator (RI), etc. While the UCI is transmitted on a PUCCH in general, the UCI may be transmitted on a PUSCH when control information and traffic data need to be simultaneously transmitted. In addition, the UCI may be aperiodically transmitted through a PUSCH according to request/command of a network. 
       FIG.  2    illustrates the structure of a NR system to which the present disclosure is applicable. 
     Referring to  FIG.  2   , a next generation radio access network (NG-RAN) may include a next generation Node B (gNB) and/or an eNB, which provides user-plane and control-plane protocol termination to a UE. In  FIG.  2   , the NG-RAN is shown as including only gNBs, by way of example. A gNB and an eNB are connected to each other via an Xn interface. The gNB and the eNB are connected to a 5G core network (5GC) via an NG interface. More specifically, the gNB and the eNB are connected to an access and mobility management function (AMF) via an NG-C interface and to a user plane function (UPF) via an NG-U interface. 
       FIG.  3    illustrates a structure of a radio frame used in NR. 
     In NR, UL and DL transmissions are configured in frames. The radio frame has a length of 10 ms and is defined as two 5 ms half-frames (HF). The half-frame is defined as five 1 ms subframes (SF). A subframe is divided into one or more slots, and the number of slots in a subframe depends on subcarrier spacing (SCS). Each slot includes 12 or 14 OFDM(A) symbols according to a cyclic prefix (CP). When a normal CP is used, each slot includes 14 symbols. When an extended CP is used, each slot includes 12 symbols. Here, the symbols may include OFDM symbols (or CP-OFDM symbols) and SC-FDMA symbols (or DFT-s-OFDM symbols). 
     [Table 1] illustrates that the number of symbols per slot, the number of slots per frame, and the number of slots per subframe vary according to the SCS when the normal CP is used. 
     
       
         
           
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 SCS (15*2{circumflex over ( )}u) 
                 N slot   symb   
                 N frame ’  u   slot   
                 N subframe, u   slot   
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                  15 kHz (u = 0) 
                 14 
                 10 
                 1 
               
               
                  30 kHz (u = 1) 
                 14 
                 20 
                 2 
               
               
                  60 kHz (u = 2) 
                 14 
                 40 
                 4 
               
               
                 120 kHz (u = 3) 
                 14 
                 80 
                 8 
               
               
                 240 kHz (u = 4) 
                 14 
                 160 
                 16 
               
               
                   
               
               
                 *N slot   symb : Number of symbols in a slot 
               
               
                 *N frame ’  u   slot : Number of slots in a frame 
               
               
                 *N subframe, u   slot : Number of slots in a subframe 
               
            
           
         
       
     
     [Table 2] illustrates that the number of symbols per slot, the number of slots per frame, and the number of slots per subframe vary according to the SCS when the extended CP is used. 
     
       
         
           
               
               
               
               
             
               
                 TABLE 2 
               
               
                   
               
               
                 SCS (15*2{circumflex over ( )}u) 
                 N slot   symb   
                 N frame ’  u   slot   
                 N subframe, u   slot   
               
               
                   
               
             
            
               
                 60 kHz (u = 2) 
                 12 
                 40 
                 4 
               
               
                   
               
            
           
         
       
     
     The frame structure is merely an example. The number of subframes, the number of slots, and the number of symbols in a frame may vary. In the NR system, different OFDM numerologies (e.g., SCSs) may be configured for a plurality of cells aggregated for one UE. Accordingly, the (absolute time) duration of a time resource including the same number of symbols (e.g., a subframe (SF), slot, or TTI) (collectively referred to as a time unit (TU) for convenience) may be configured to be different for the aggregated cells. A symbol may be an OFDM symbol (or CP-OFDM symbol) or an SC_FDMA symbol (or a discrete Fourier transform-spread-OFDM (DFT-s-OFDM) symbol). 
     In NR, various numerologies (or SCSs) are supported to support various 5G services. For example, with an SCS of 15 kHz, a wide area in traditional cellular bands is supported, while with an SCS of 30/60 kHz, a dense urban area, a lower latency, and a wide carrier bandwidth are supported. With an SCS of 60 kHz or higher, a bandwidth larger than 24.25 GHz is be supported to overcome phase noise. 
     An NR frequency band may be defined by two types of frequency ranges, FR1 and FR2. FR1 and FR2 may be configured as described in Table 3. FR2 may refer to millimeter wave (mmW). 
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 3 
               
               
                   
                   
               
               
                   
                 Frequency Range 
                 Corresponding  
                   
               
               
                   
                 designation 
                 frequency range 
                 Subcarrier Spacing 
               
               
                   
                   
               
             
            
               
                   
                 FR1 
                  450 MHz-7125 MHz 
                  15, 30, 60 kHz 
               
               
                   
                 FR2 
                 24250 MHz-52600 MHz 
                 60, 120, 240 kHz 
               
               
                   
                   
               
            
           
         
       
     
       FIG.  4    illustrates a resource grid of a slot. A slot includes a plurality of symbols in the time domain. For example, when the normal CP is used, the slot includes 14 symbols. However, when the extended CP is used, the slot includes 12 symbols. A carrier includes a plurality of subcarriers in the frequency domain. A resource block (RB) is defined as a plurality of consecutive subcarriers (e.g., 12 consecutive subcarriers) in the frequency domain. A bandwidth part (BWP) may be defined to be a plurality of consecutive physical RBs (PRBs) in the frequency domain and correspond to a single numerology (e.g., SCS, CP length, etc.). The carrier may include up to N (e.g., 5) BWPs. Data communication may be performed through an activated BWP, and only one BWP may be activated for one UE. In the resource grid, each element is referred to as a resource element (RE), and one complex symbol may be mapped to each RE. 
     Hereinafter, a hybrid automatic repeat request-acknowledgement (HARQ-ACK) operation will be described in detail. 
       FIG.  5    is a diagram for explaining a HARQ-ACK operation. 
     HARQ-ACK information is information indicating whether a UE successfully receives a DL signal (e.g., DL control signal or DL data signal). Hereinafter, a UE may be referred to as a terminal according to embodiments. When a UE successfully receives a DL signal, the UE may transmit an acknowledgement (ACK) to a BS. When the UE does not successfully receive a DL signal, the UE may transmit a negative ACK (NACK) to the BS. 
     In NR, a HARQ-ACK may have the following characteristics: 1) and 2). 
     1) 1-bit HARQ-ACK feedback may be supported for each transport block (TB). In this document, HARQ-ACK feedback may have the same meaning as HARQ feedback. In this case, the operation of one DL HARQ process may be supported for some UEs, while the operation of one or more DL HARQ processes may be supported for a given UE. 
     2) The UE may support a set of minimum HARQ processing time. Here, the minimum HARQ processing time means the minimum time required for the UE to transmit a HARQ-ACK for DL data (e.g., PDSCH) after receiving the DL data. For the minimum HARQ processing time, two types of UE processing times (N1 and K1) may be defined depending on (1) symbol granularity and (2) slot granularity, where K1 may mean the number of slots from a slot for the PDSCH to a slot for the HARQ-ACK related to the PDSCH. That is, K1 may mean the number of slots from the slot in which the PDSCH is received to the slot in which the HARQ-ACK related to the PDSCH is transmitted. 
     From the viewpoint of the UE, N1 may mean the number of OFDM symbols required for UE processing from the end of the PDSCH reception to the earliest start time of the HARQ-ACK transmission related to the PDSCH. That is, N1 may mean the number of OFDM symbols required for UE processing from the time when the PDSCH reception ends to the earliest time when transmission of the HARQ-ACK related to the PDSCH starts. N1 may be defined as shown in Tables 4 and 5 below according to OFDM numerologies (i.e., subcarrier spacing) and DMRS patterns. 
     
       
         
           
               
               
               
               
               
               
               
             
               
                 TABLE 4 
               
               
                   
               
               
                   
                 HARQ Timing 
                   
                 15 kHz 
                 30 kHz 
                 60 kHz 
                 120 kHz 
               
               
                 configuration 
                 Parameter 
                 Units 
                 SCS 
                 SCS 
                 SCS 
                 SCS 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Front-loaded 
                 N1 
                 Symbols 
                 8 
                 10 
                 17 
                 20 
               
               
                 DMRS only 
               
               
                 Front-loaded DMRS 
                 N1 
                 Symbols 
                 13 
                 13 
                 20 
                 24 
               
               
                 only + additional DMRS 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
               
             
               
                 TABLE 5 
               
               
                   
               
               
                   
                 HARQ  
                   
                 15  
                 30  
                 60  
               
               
                   
                 Timing 
                   
                 kHz 
                 kHz 
                 kHz 
               
               
                 configuration 
                 Parameter 
                 Units 
                 SCS 
                 SCS 
                 SCS 
               
               
                   
               
             
            
               
                 Front-loaded 
                 N1 
                 Symbols 
                  3 
                   4.5 
                 9(FR1) 
               
               
                 DMRS only 
                   
                   
                   
                   
                   
               
               
                 Front-loaded DMRS 
                 N1 
                 Symbols 
                 [13] 
                 [13] 
                 [20] 
               
               
                 only + additional DMRS 
               
               
                   
               
            
           
         
       
     
     Referring to  FIG.  5   , a HARQ-ACK timing, K1 may mean the number of slots from a slot for a PDSCH to a slot for a HARQ-ACK related to the PDSCH. K0 denotes the number of slots from a slot having a DL grant PDCCH to a slot having related PDSCH transmission, and K2 denotes the number of slots from a slot having a UL grant PDCCH to a slot having related PUSCH transmission. Specifically, K1 may mean the number of slots from a slot in which a PDSCH is received to a slot in which a HARQ-ACK related to the PDSCH is transmitted. K0 may mean the number of slots from a slot in which a DL grant PDCCH is received to a slot in which a PDSCH related to the PDCCH is received. In addition, K2 may mean the number of slots from a slot in which a PDCCH including a UL grant is received to a slot in which a PUSCCH related to the PDCCH is transmitted. That is, KO, K1, and K2 may be briefly summarized as shown in Table 6 below. 
     
       
         
           
               
               
               
             
               
                 TABLE 6 
               
               
                   
               
               
                   
                 A 
                 B 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 K0 
                 DL scheduling DCI 
                 Corresponding DL data transmission 
               
               
                 K1 
                 DL data reception 
                 Corresponding HARQ-ACK 
               
               
                 K2 
                 UL scheduling DCI 
                 Corresponding UL data transmission 
               
               
                   
               
            
           
         
       
     
     The BS may provide a HARQ-ACK feedback timing to the UE dynamically in DCI or semi-statically through RRC signaling. For example, when a HARQ-ACK feedback timing is dynamically provided by DCI, a slot timing between A and B may be indicated among a set of values by a specific field in the DCI from a set of values. In addition, NR supports different minimum HARQ processing times between UEs. The HARQ processing time may include a delay between the reception timing of DL data and the transmission timing of a HARQ-ACK related to the DL data and a delay between the reception timing of a UL grant and the transmission timing of UL data related to the UL grant. The UE may provide its capability regarding the minimum HARQ processing time to the BS. Asynchronous and adaptive DL HARQ may be supported at least for eMBB and URLLC. 
     Table 7 shows a timing from when a PDSCH is received to when HARQ-ACK information is transmitted, which is an excerpt from TS 38.214. In Table 7, parameters d 1,1  and d 2  may be determined according to TS 38.214 and TS 38.211. 
     [Table 7] 
     
       
         
           
               
             
               
                 TABLE 7 
               
               
                   
               
             
            
               
                 If the first uplink symbol of the PUCCH which carries the  
               
               
                 HARQ-ACK information, as defined by the assigned  
               
               
                 HARK-ACK timing K1 and the PUCCH resource to be used  
               
               
                 and including the effect of the timing advance, starts no 
               
               
                 earlier than at symbol L1, when L1 is defined as the next  
               
               
                 uplink symbol with its CP starting after    after the end of the  
               
               
                 last symbol of the PDSCH carrying the TB being acknowledged,  
               
               
                 then the UE shall provide a valid HARQ-ACK message. 
               
               
                     is based on p of table 5.3-1 and table 3.3-2 for  
               
               
                 UE processing capability    and   , where    corresponds to  
               
               
                 the one of    resulting with the largest    where the    
               
               
                 subcarrier spacing of the scheduled PDSCM and   corresponds to  
               
               
                 the subcarrier spacing of the uplink channel with which  
               
               
                 the BARQ-ACK is    and    is defined in clause    
               
               
                 Otherwise the UE may not provide a valid HARQ-ACK  
               
               
                 corresponding to the scheduled PDSCH. The value of     
               
               
                 is used both in the case of normal and extended cyclic prefix. 
               
               
                 For a PDSCH that consists of two PDSCH transmission occasions  
               
               
                 in time domain in one slot,    is calculated based on the first  
               
               
                 PDSCH transmission occasion in the slot, and as described above. 
               
               
                   
               
               
                 Table 5.3-1: PDSCH pocessing time for PDSCH processing capability 1 
               
               
                 PDSCH decoding time N 1  (symbols) 
               
            
           
           
               
               
               
            
               
                   
                 dmrs-AdditionalPosition =  
                 dmrs-AdditionalPosition    pos0 in 
               
               
                   
                 pos0 in DMRS-  
                 DMRS-DownlinkConfig in either of 
               
               
                   
                 DownlinkContig in both of 
                 dmrs-DownlinkForPDSCH- 
               
               
                   
                 dmrs-DownlinkForPDSCH- 
                 MappingTypeA, dmrs- 
               
               
                   
                 MappingTypeA, dmrs- 
                 DownlinkForPDSCH-MappingTypeB 
               
               
                   
                 DownlinkFor PDSCH- 
                 or if the higher layer  
               
               
                 μ 
                 Mapping TypeB 
                 parameter is not configured 
               
               
                   
               
               
                 0 
                 8 
                 
                   
                 
               
               
                 1 
                 10 
                 13 
               
               
                 2 
                 17 
                 20 
               
               
                 3 
                 20 
                 24 
               
               
                   
               
            
           
           
               
            
               
                 Table 5.3-2: PDSCH processing time for PDSCH processing capability 2 
               
            
           
           
               
               
            
               
                   
                 PDSCH decoding time N 1  (symbols) 
               
               
                   
                 dmrs-AdditionalPosition = pos0 in 
               
               
                   
                 DMRS-DownlinkConfig in both of 
               
               
                   
                 dmrs-DownlinkForPDSCH-MappingTypeA, 
               
               
                 μ 
                 dmrs-DownlinkFor PDSCH-MappingTypeB 
               
               
                   
               
               
                 0 
                 3 
               
               
                 1 
                 4.5 
               
               
                 2 
                 μ for frequency range 1 
               
               
                   
               
               
                     indicates data missing or illegible when filed 
               
            
           
         
       
     
     From the perspective of the UE, HARQ ACK/NACK feedback on multiple DL transmissions in the time domain may be transmitted in one UL data/control region. The timing between reception of DL data and transmission of an acknowledgment related to the received DL data may be indicated by a field in DCI from a set of values, and the set of values may be configured by higher layers. The timing is defined at least when the timing is not known to the UE. 
     HARQ-ACK Codebook 
     In NR, a dynamic HARQ-ACK codebook and a semi-static HARQ-ACK codebook may be supported. A HARQ-ACK codebook may be replaced with a HARQ-ACK payload. 
     For the dynamic HARQ-ACK codebook, a total downlink assignment index (T-DAI) field and/or a counter downlink assignment index (C-DAI) field may be configured in DCI. The UE may generate HARQ-ACK information for a PDSCH actually scheduled by PDCCH monitoring occasions based on T-DAI and/or C-DAI values and transmit the information to the BS. The dynamic HARQ-ACK codebook may be referred to as a Type 2 HARQ-ACK codebook, which will be described later. 
     When the dynamic HARQ-ACK codebook is configured, the size of a HARQ-ACK payload may change depending on the amount of scheduled DL data. To this end, a PDCCH scheduling a DL signal may include a C-DAI and a T-DAI. The C-DAI indicates a scheduling order of {CC, slot} calculated in a component carrier (CC) first manner (or in a cell first manner) and is used to designate the position of a HARQ-ACK bit in the HARQ-ACK codebook. The T-DAI indicates a slot-level scheduling cumulative value up to the current slot and is used to determine the size of the HARQ-ACK codebook. 
     For the semi-static HARQ-ACK codebook, HARQ-ACK bit(s) may be generated for all PDCCH monitoring occasions associated with a specific PUCCH transmission time and then transmitted in consideration of multiple PDSCH-to-HARQ-ACK feedback timings configured to the UE. The semi-static HARQ-ACK codebook may be referred to as a Type 1 HARQ-ACK codebook, which will be described later. In the semi-static HARQ-ACK codebook, a PDSCH that is not scheduled on the PDCCH monitoring occasions may be regarded as a NACK 
     When carrier aggregation is applied, HARQ-ACK transmissions for multiple cells may be multiplexed and transmitted on one PUCCH. 
     Non-Terrestrial Networks Reference 
       FIG.  6    illustrates a non-terrestrial network (NTN). 
     A non-terrestrial network (NTN) refers to a wireless network configured using satellites (e.g., geostationary earth orbit satellites (GEO)/low-earth orbit satellites (LEO)). Based on the NTN, coverage may be extended and a highly reliable network service may be provided. For example, the NTN may be configured alone, or may be combined with a conventional terrestrial network to configure a wireless communication system. For example, in the NTN network, i) a link between a satellite and a UE, ii) a link between satellites, iii) a link between a satellite and a gateway, and the like may be configured. 
     The following terms may be used to describe the configuration of a wireless communication system employing satellites. 
     Satellite: a space-borne vehicle embarking a bent pipe payload or a regenerative payload telecommunication transmitter, placed into Low-Earth Orbit (LEO) typically at an altitude between 500 km to 2000 km, Medium-Earth Orbit (MEO) typically at an altitude between 8000 to 20000 lm, or Geostationary satellite Earth Orbit (GEO) at 35 786 km altitude. 
     Satellite network: Network, or segments of network, using a space-borne vehicle to embark a transmission equipment relay node or base station. 
     Satellite RAT: a RAT defined to support at least one satellite. 
     5G Satellite RAT: a Satellite RAT defined as part of the New Radio. 
     5G satellite access network: 5G access network using at least one satellite. 
     Terrestrial: located at the surface of Earth. 
     Terrestrial network: Network, or segments of a network located at the surface of the Earth. 
     Use cases that may be provided by a communication system employing a satellite connection may be divided into three categories. The “Service Continuity” category may be used to provide network connectivity in geographic areas where 5G services cannot be accessed through the wireless coverage of terrestrial networks. For example, a satellite connection may be used for a UE associated with a pedestrian user or a UE on a moving land-based platform (e.g., car, coach, truck, train), air platform (e.g., commercial or private jet) or marine platform (e.g., marine vessel). In the “Service Ubiquity” category, when terrestrial networks are unavailable (due to, for example, disaster, destruction, economic situations, etc.), satellite connections may be used for IOT/public safety-related emergency networks/home access, etc. The “Service Scalability” category includes services using wide coverage of satellite networks. 
     For example, a 5G satellite access network may be connected to a 5G core Network. In this case, the satellite may be a bent pipe satellite or a regenerative satellite. The NR radio protocols may be used between the UE and the satellite. Also, F1 interface may be used between the satellite and the gNB. 
     As described above, a non-terrestrial network (NTN) refers to a wireless network configured using a device that is not fixed on the ground, such as satellite. A representative example is a satellite network. Based on the NTN, coverage may be extended and a highly reliable network service may be provided. For example, the NTN may be configured alone, or may be combined with an existing terrestrial network to configure a wireless communication system. 
     Use cases that may be provided by a communication system employing an NTN may be divided into three categories. The “Service Continuity” category may be used to provide network connectivity in geographic areas where 5G services cannot be accessed through the wireless coverage of terrestrial networks. For example, a satellite connection may be used for a UE associated with a pedestrian user or a UE on a moving land-based platform (e.g., car, coach, truck, train), air platform (e.g., commercial or private jet) or marine platform (e.g., marine vessel). In the “Service Ubiquity” category, when terrestrial networks are unavailable (due to, for example, disaster, destruction, economic situations, etc.), satellite connections may be used for IOT/public safety-related emergency networks/home access, etc. The “Service Scalability” category includes services using wide coverage of satellite networks. 
     Referring to  FIG.  6   , the NTN includes one or more satellites  410 , one or more NTN gateways  420  capable of communicating with the satellites, and one or more UEs (/BSs)  430  capable of receiving mobile satellite services from the satellites. For simplicity, the description is focused on the example of the NTN including satellites, but is not intended to limit the scope of the present disclosure. Accordingly, the NTN may include not only the satellites, but also aerial vehicles (Unmanned Aircraft Systems (UAS) encompassing tethered UAS (TUA), Lighter than Air UAS (LTA), Heavier than Air UAS (HTA), all operating in altitudes typically between 8 and 50 km including High Altitude Platforms (HAPs)). 
     The satellite  410  is a space-borne vehicle equipped with a bent pipe payload or a regenerative payload telecommunication transmitter and may be located in a low earth orbit (LEO), a medium earth orbit (MED), or a geostationary earth orbit (GEO). The NTN gateway  420  is an earth station or gateway existing on the surface of the earth, and provides sufficient RF power/sensitivity to access the satellite. The NTN gateway corresponds to a transport network layer (TNL) node. 
     The NTN may have i) a link between a satellite and a UE, ii) a link between satellites, iii) a link between a satellite and an NTN gateway. A service link refers to a radio link between a satellite and a UE. Inter-satellite links (ISLs) between satellites may be present when there are multiple satellites. A feeder link refers to a radio link between an NTN gateway and a satellite (or UAS platform). The gateway may be connected to a data network and may communicate with a satellite through the feeder link. The UE may communicate via the satellite and service link. 
     As NTN operation scenarios, two scenarios which are based on transparent payload and regenerative payload, respectively may be considered.  FIG.  6   -( a ) shows an example of a scenario based on a transparent payload. In the scenario based on the transparent payload, the signal repeated by the payload is not changed. The satellites  410  repeat the NR-Uu radio interface from the feeder link to the service link (or vice versa), and the satellite radio interface (SRI) on the feeder link is NR-Uu. The NTN gateway  420  supports all functions necessary to transfer the signal of the NR-Uu interface. Also, different transparent satellites may be connected to the same gNB on the ground.  FIG.  6   -( b ) shows an example of a scenario based on a regenerative payload. In the scenario based on the regenerative payload, the satellite  410  may perform some or all of the functions of a conventional BS (e.g., gNB), and may thus perform some or all of frequency conversion/demodulation/decoding/modulation. The service link between the UE and a satellite is established using the NR-Uu radio interface, and the feeder link between the NTN gateway and a satellite is established using the satellite radio interface (SRI). The SRI corresponds to a transport link between the NTN gateway and the satellite. 
     The UE  430  may be connected to 5GCN through an NTN-based NG-RAN and a conventional cellular NG-RAN simultaneously. Alternatively, the UE may be connected to the 5GCN via two or more NTNs (e.g., LEO NTN and GEO NTN, etc.) simultaneously. 
       FIG.  7    illustrates an overview and a scenario of an NTN. 
     NTN refers to a network or network segment in which a satellite (or UAS platform) uses RF resources. Typical scenarios of the NTN providing access to a UE include an NTN scenario based on a transparent payload as shown in  FIG.  7   -( a ) and an NTN scenario based on a regenerative payload as shown in  FIG.  7   -( b ). 
     NTN typically features the following elements, 
     One or several sat-gateways that connect the Non-Terrestrial Network to a public data network 
     A GEO satellite is fed by one or several sat-gateways which are deployed across the satellite targeted coverage (e.g. regional or even continental coverage). We assume that UE in a cell is served by only one sat-gateway. 
     A Non-GEO satellite served successively by one or several sat-gateways at a time. The system ensures service and feeder link continuity between the successive serving sat-gateways with sufficient time duration to proceed with mobility anchoring and hand-over. 
     A feeder link or radio link between a sat-gateway and the satellite (or UAS platform) 
     A service link or radio link between the user equipment and the satellite (or UAS platform). 
     A satellite (or UAS platform) which may implement either a transparent or a regenerative (with on board processing) payload. The satellite (or UAS platform) generates beams typically generate several beams over a given service area bounded by its field of view. The footprints of the beams are typically of elliptic shape. The field of view of a satellites (or UAS platforms) depends on the on board antenna diagram and min elevation angle. 
     A transparent payload: Radio Frequency filtering, Frequency conversion and amplification. Hence, the waveform signal repeated by the payload is un-changed; 
     A regenerative payload: Radio Frequency filtering, Frequency conversion and amplification as well as demodulation/decoding, switch and/or routing, coding/modulation. This is effectively equivalent to having all or part of base station functions (e.g. gNB) on board the satellite (or UAS platform). 
     Inter-satellite links (ISL) optionally in case of a constellation of satellites. This will require regenerative payloads on board the satellites. ISL may operate in RF frequency or optical bands. 
     User Equipment is served by the satellite (or UAS platform) within the targeted service area. 
     Table 8 below defines various types of satellites (or UAS platforms). 
     
       
         
           
               
               
               
               
             
               
                 TABLE 8 
               
               
                   
               
               
                   
                   
                   
                 Typical 
               
               
                   
                   
                   
                 beam 
               
               
                   
                   
                   
                 footprint 
               
               
                 Platforms 
                 Altitude range 
                 Orbit 
                 size 
               
               
                   
               
             
            
               
                 Low-Earth 
                  300-1500 km 
                 Circular around the  
                 100- 
               
               
                 Orbit (LEO) 
                   
                 earth 
                 1000 km 
               
               
                 satellite 
                   
                   
                   
               
               
                 Medium-Earth 
                  7000-25000 km 
                   
                 100- 
               
               
                 Orbit (MEO) 
                   
                   
                 1000 km 
               
               
                 satellite 
                   
                   
                   
               
               
                 Geostationary 
                 35 786 km 
                 notional station keeping  
                 200- 
               
               
                 Earth Orbit 
                   
                 position fixed in terms of 
                 3500 km 
               
               
                 (GEO) satellite 
                   
                 elevation/azimuth with  
                   
               
               
                 UAS platform 
                 8-50 km (20 km  
                 respect to a given  
                 5-200 
               
               
                 (including 
                 for HAPS) 
                 earth point 
                 km 
               
               
                 HAPS) 
                   
                   
                   
               
               
                 High Elliptical 
                  400-50000 km 
                 Elliptical around the  
                 200- 
               
               
                 Orbit (HEO) 
                   
                 earth 
                 3500 km 
               
               
                 satellite 
               
               
                   
               
            
           
         
       
     
     Typically, GEO satellite and UAS are used to provide continental, regional or local service. A constellation of LEO and MEO is used to provide services in both Northern and Southern hemispheres. In some case, the constellation can even provide global coverage including polar regions. For the later, this requires appropriate orbit inclination, sufficient beams generated and inter-satellite links. HEO satellite systems are not considered in this document. 
     An NTN that provides access to a terminal in six reference scenarios described below can be considered. 
     Circular orbiting and notional station keeping platforms. 
     Highest RTD constraint 
     Highest Doppler constraint 
     A transparent and a regenerative payload 
     One ISL case and one without ISL. Regenerative payload is mandatory in the case of inter-satellite links. 
     Fixed or steerable beams resulting respectively in moving or fixed beam foot print on the ground 
     Six scenarios are considered as depicted in Table 9 and are detailed in Table 10. 
     
       
         
           
               
               
               
             
               
                 TABLE 9 
               
               
                   
               
               
                   
                 Transparent  
                 Regenerative  
               
               
                   
                 satellite 
                 satellite 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 GEO based non-terrestrial access network 
                 Scenario A  
                 Scenario B  
               
               
                 LEO based non-terrestrial access network: 
                 Scenario C1 
                 Scenario D1 
               
               
                 steerable beams 
                   
                   
               
               
                 LEO based non-terrestrial access network: 
                 Scenario C2 
                 Scenario D2 
               
               
                 the beams move with the satellite 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
             
               
                 TABLE 10 
               
             
            
               
                   
               
               
                   
                 Scenarios 
               
            
           
           
               
               
               
            
               
                   
                 GEO based non-  
                 LEO based non- 
               
               
                   
                 terrestrial access  
                 terrestrial access  
               
               
                   
                 network 
                 network 
               
               
                   
                 (Scenario A and B) 
                 (Scenario C &amp; D) 
               
               
                   
               
               
                 Orbit type 
                 notional station  
                 circular orbiting  
               
               
                   
                 keeping position  
                 around the earth 
               
               
                   
                 fixed in terms of 
                   
               
               
                   
                 elevation/azimuth  
                   
               
               
                   
                 rwith espect to a  
                   
               
               
                   
                 given earth point 
                   
               
               
                 Altitude 
                 35,786 km 
                   600 km 
               
               
                   
                   
                 1,200 km 
               
            
           
           
               
               
            
               
                 Spectrum  
                 &lt;6 GHz (e.g. 2 GHz) 
               
               
                 (service link) 
                 &gt;6 GHz (e.g. DL 20 GHz, UL 30 GHz) 
               
               
                 Max channel  
                 30 MHz for band &lt;6 GHz 
               
               
                 bandwidth  
                  1 GHz for band &gt;6 GHz 
               
               
                 capability 
                   
               
               
                 (service link) 
                   
               
            
           
           
               
               
               
            
               
                 Payload 
                 Scenario A:  
                 Scenario C:  
               
               
                   
                 Transparent (including  
                 Transparent (including  
               
               
                   
                 radio frequency 
                 radio frequency 
               
               
                   
                 function only) 
                 function only) 
               
               
                   
                 Scenario B:  
                 Scenario D:  
               
               
                   
                 regenerative 
                 Regenerative 
               
               
                   
                 (including all or part  
                 (including all or part  
               
               
                   
                 of RAN functions) 
                 of RAN functions) 
               
               
                 Inter-Satellite link 
                 No 
                 Scenario C: No 
               
               
                   
                   
                 Scenario D:  
               
               
                   
                   
                 Yes/No (Both 
               
               
                   
                   
                 cases are possible.) 
               
               
                 Earth-fixed beams 
                 Yes 
                 Scenario C1:  
               
               
                   
                   
                 Yes (steerable 
               
               
                   
                   
                 beams), see note 1 
               
               
                   
                   
                 Scenario C2: No move  
               
               
                   
                   
                 (the beams 
               
               
                   
                   
                 with the satellite) 
               
               
                   
                   
                 Scenario D 1: Yes  
               
               
                   
                   
                 (steerable beams),  
               
               
                   
                   
                 see note 1 
               
               
                   
                   
                 Scenario D 2: No (the  
               
               
                   
                   
                 beams move  
               
               
                   
                   
                 with the satellite) 
               
               
                 Max beam foot  
                 3500 km (Note 5) 
                 1000 km 
               
               
                 print size  
                   
                   
               
               
                 (edge to edge) 
                   
                   
               
               
                 regardless of the 
                   
                   
               
               
                 elevation angle 
                   
                   
               
               
                 Min Elevation  
                 10° for service link and  
                 10° for service link and  
               
               
                 angle for both  
                 10° for feeder link 
                 10° for feeder link 
               
               
                 sat-gateway 
                   
                   
               
               
                 and user equipment 
                   
                   
               
               
                 Max distance  
                 40,581 km 
                 1,932 km  
               
               
                 between satellite  
                   
                 (600 km altitude) 
               
               
                 and user 
                   
                 3,131 km  
               
               
                 equipment at min 
                   
                 (1,200 km altitude) 
               
               
                 elevation angle 
                   
                   
               
               
                 Max Round Trip  
                 Scenario A: 541.46 ms  
                 Scenario C: (transparent 
               
               
                 Delay (propagation  
                 (service and  
                 payload: service  
               
               
                 delay only) 
                 feeder links) 
                 and feeder links) 
               
               
                   
                 Scenario B: 270.73 ms  
                 −25.77 ms (600 km)  
               
               
                   
                 (service link only) 
                 −41.77 ms (1200 km) 
               
               
                   
                   
                 Scenario D:  
               
               
                   
                   
                 (regenerative payload:  
               
               
                   
                   
                 service link only) 
               
               
                   
                   
                 −12.89 ms (600 km)  
               
               
                   
                   
                 −20.89 ms (1200 km) 
               
               
                 Max differential  
                 10.3 ms 
                 3.12 ms and 3.18 ms for 
               
               
                 delay within a cell  
                   
                 respectively 600 km  
               
               
                 (Note 6) 
                   
                 and 1200 km 
               
               
                 Max Doppler shift 
                 0.93 ppm 
                 24 ppm (600 km)  
               
               
                 (earth fixed user 
                   
                 21 ppm (1200 km) 
               
               
                 equipment) 
                   
                   
               
               
                 Max Doppler shift 
                 0.000 045 ppm/s 
                 0.27 ppm/s (600 km ) 
               
               
                 variation  
                   
                 0.13 ppm/s (1200 km) 
               
               
                 (earth fixed 
                   
                   
               
               
                 user equipment) 
                   
                   
               
               
                 User equipment  
                 1200 km/h  
                 500 km/h (e.g.  
               
               
                 motion on the  
                 (e.g. aircraft) 
                 high speed train) 
               
               
                 earth 
                   
                 Possibly 1200 km/h  
               
               
                   
                   
                 (e.g. aircraft) 
               
            
           
           
               
               
            
               
                 User equipment 
                 Omnidirectional antenna (linear  
               
               
                 antenna types 
                 polarisation), assuming 0 dBi  
               
               
                   
                 Directive antenna (up to 60 cm equivalent  
               
               
                   
                 aperture diameter in circular polarisation) 
               
               
                 User equipment  
                 Omnidirectional antenna: UE power  
               
               
                 Tx 
                 class 3 with up to 200 mW 
               
               
                 power 
                 Directive antenna: up to 20 W 
               
               
                 User equipment  
                 Omnidirectional antenna: 7 dB 
               
               
                 Noise figure 
                 Directive antenna: 1.2 dB 
               
               
                 Service link 
                 3GPP defined New Radio 
               
            
           
           
               
               
               
            
               
                 Feeder link 
                 3GPP or non- 
                 3GPP or non- 
               
               
                   
                 3GPP defined  
                 3GPP defined  
               
               
                   
                 Radio interface 
                 Radio interface 
               
               
                   
               
               
                 NOTE 1: 
               
               
                 Each satellite has the capability to steer beams towards fixed points on earth using beamforming techniques. This is applicable for a period of time corresponding to the visibility time of the satellite 
               
               
                 NOTE 2: 
               
               
                 Max delay variation within a beam (earth fixed user equipment) is calculated based on Min Elevation angle for both gateway and user equipment 
               
               
                 NOTE 3: 
               
               
                 Max differential delay within a beam is calculated based on Max beam foot print diameter at nadir 
               
               
                 NOTE 4: 
               
               
                 Speed of light used for delay calculation is 299792458 m/s. 
               
               
                 NOTE 5: 
               
               
                 The Maximum beam foot print size for GEO is based on current state of the art GEO High Throughput systems, assuming either spot beams at the edge of coverage (low elevation). 
               
               
                 NOTE 6: 
               
               
                 The maximum differential delay at cell level has been computed considering the one at beam level for largest beam size. It doesn’t preclude that cell may include more than one beam when beam size are small or medium size. However the cumulated differential delay of all beams within a cell will not exceed the maximum differential delay at cell level in the table above. 
               
            
           
         
       
     
     The NTN study results apply to GEO scenarios as well as all NGSO scenarios with circular orbit at altitude greater than or equal to 600 km. 
     Hereinafter, the NTN reference point will be described. 
       FIG.  8    illustrates TA components of the NTN. Here, the TA offset (NTAoffset) may not be plotted. 
     With consideration on the larger cell coverage, long round trip time (RTT) and high Doppler, enhancements are considered to ensure the performance for timing and frequency synchronization for UL transmission. 
     Referring to  FIG.  8   , a reference point related to timing advance (TA) of initial access and subsequent TA maintenance/management is illustrated. Terms defined in relation to  FIG.  8    are described below. 
     Option 1: Autonomous acquisition of the TA at UE with UE known location and satellite ephemeris. 
     Regarding option 1, the required TA value for UL transmission including PRACH can be calculated by the UE. The corresponding adjustment can be done, either with UE-specific differential TA or full TA (consisting of UE specific differential TA and common TA). 
     Except the full TA compensation at the UE side, both the alignment on the UL timing among UEs and DL and UL frame timing at network side can be achieved. However, in case of satellite with transparent payload, further discussion on how to handle the impact introduced by feeder link will be conducted in normative work. Additional needs for the network to manage the timing offset between the DL and UL frame timing can be considered, if impacts introduced by feeder link is not compensated by UE in corresponding compensation. 
     Except the UE specific differential TA only, additional indication on a single reference point should be signalled to UEs per beam/cell for achieving the UL timing alignment among UEs within the coverage of the same beam/cell. Timing offset between DL and UL frame timing at the network side should also be managed by the network regardless of the satellite payload type. 
     With concern on the accuracy on the self-calculated TA value at the UE side, additional TA signalling from network to UE for TA refinement, e.g., during initial access and/or TA maintenance, can be determined in the normative work. 
     Option 2: Timing advanced adjustment based on network indication 
     Regarding option 2, the common TA, which refers to the common component of propagation delay shared by all UEs within the coverage of same satellite beam/cell, is broadcasted by the network per satellite beam/cell. The calculation of this common TA is conducted by the network with assumption on at least a single reference point per satellite beam/cell. 
     The indication for UE-specific differential TA from network as the Rel-15 TA mechanism is also needed. For satisfying the larger coverage of NTN, extension of value range for TA indication in RAR, either explicitly or implicitly, is identified. Whether to support negative TA value in corresponding indication will be determined in the normative phase. Moreover, indication of timing drift rate, from the network to UE, is also supported to enable the TA adjustment at UE side. 
     For calculation of common TA in the above two options, single reference point per beam is considered as the baseline. Whether and how to support the multiple reference points can be further discussed in the normative work. 
     For the UL frequency compensation, at least for LEO system, the following solutions are identified with consideration on the beam specific post-compensation of common frequency offset at the network side: 
     Regarding option 1, both the estimation and pre-compensation of UE-specific frequency offset are conducted at the UE side. The acquisition of this value can be done by utilizing DL reference signals, UE location and satellite ephemeris. 
     Regarding option 2, the required frequency offset for UL frequency compensation at least in LEO systems is indicated by the network to UE. The acquisition on this value can be done at the network side with detection of UL signals, e.g., preamble. 
     Indication of compensated frequency offset values by the network is also supported in case that compensation of the frequency offset is conducted by the network in the uplink and/or the downlink, respectively. However, indication of Doppler drift rate is not necessary. 
     Hereinafter, more delay-tolerant re-transmission mechanisms will be described in detail. 
     As follows, two main aspects of a retransmission mechanism with improved delay tolerance can be discussed. 
     Disabling of HARQ in NR NTN 
     HARQ optimization in NR-NTN 
     HARQ Round Trip Time in NR is of the order of several ms. The propagation delays in NTN are much longer, ranging from several milliseconds to hundreds of milliseconds depending on the satellite orbit. The HARQ RTT can be much longer in NTN. It was identified early in the study phase that there would be a need to discuss potential impact and solutions on HARQ procedure. RAN1 has focused on physical layer aspects while RAN2 has focused on MAC layer aspects. 
     In this regard, disabling of HARQ in NR NTN may be considered. 
     It was discussed that when UL HARQ feedback is disabled, there could be issues if {circle around (1)} MAC CE and RRC signalling are not received by UE, or {circle around (2)} DL packets not correctly received by UE for a long period of time without gNB knowing it. 
     The following were discussed without convergence on the necessity of introducing such solutions for NTN when HARQ feedback is disabled 
     (1) Indicate HARQ disabling via DCI in new/re-interpreted field [60], [61] 
     (2) New UCI feedback for reporting DL transmission disruption and or requesting DL scheduling changes [62], [63] 
     The following possible enhancements for slot-aggregation or blind repetitions were considered. There is no convergence on the necessity of introducing such enhancements for NTN. 
     (1) Greater than 8 slot-aggregation [64] 
     (2) Time-interleaved slot aggregation [65] 
     (3) New MCS table [66] 
     Next, a method for optimizing HARQ for the NR NTN will be described. 
     Solutions to avoid reduction in peak data rates in NTN were discussed. One solution is to increase the number of HARQ processes to match the longer satellite round trip delay to avoid stop-and-wait in HARQ procedure. Another solution is to disable UL HARQ feedback to avoid stop-and-wait in HARQ procedure and rely on RLC ARQ for reliability. The throughput performance for both types of solutions was evaluated at link level and system level by several contributing companies. 
     The observations from the evaluations performed on the effect of the number of HARQ processes on performance are summarized as follows: 
     Three sources [72][64][70] provided link-level simulations of throughput versus SNR with the following observations: 
     One source simulated with a TDL-D suburban channel with elevation angle of 30 degrees with BLER target of 1% for RLC ARQ with 16 HARQ processes, and BLER targets 1% and 10% with 32/64/128/256 HARQ processes. There was no observable gain in throughput with increased number of HARQ processes compared to RLC layer re-transmission with RTT in {32, 64, 128, 256} ms. 
     One source simulated with a TDL-D suburban channel with elevation angle of 30 degrees with BLER targets of 0.1% for RLC ARQ with 16 HARQ processes, and BLER targets 1% and 10% with 32 HARQ processes. An average throughput gains of 10% was observed with 32 HARQ processes compared to RLC ARQ with 16 HARQ processes with RTT=32 ms. 
     One source provides the simulation results in following cases with RTT=32 ms, e.g., assuming BLER targets at 1% for RLC ARQ with 16 HARQ processes, BLER targets 1% and 10% with 32 HARQ processes. There is no observable gain in throughput with 32 HARQ processes compared to RLC ARQ with 16 HARQ processes in case that channel is assumed as TDL-D with delay spread/ K-factor taken from system channel model in suburban scenario with elevation angle 30. Performance gain can be observed with other channels, especially, up to 12.5% spectral efficiency gain is achieved in case that channel is assumed as TDL-A in suburban with 30° elevation angle. Moreover, simulation based on the simulation with consideration on other scheduling operations: (i) additional MCS offset, (ii) MCS table based on lower efficiency (iii) slot aggregation with different BLER targets are conducted. Significant gain can be observed with enlarging the HARQ process number. 
     One source [73] provided system level simulations for LEO=1200 km with 20% resource utilization, 16 and 32 HARQ processes, 15 and 20 UEs per cell, proportional fair scheduling, and no frequency re-use. The spectral efficiency gain per user with 32 HARQ processes compared to 16 HARQ processes depends on the number of UEs. With 15 UEs per beam, an average spectral efficiency gain of 12% at 50% per centile is observed. With 20 UEs per cell there is no observable gain. 
     The following options were considered with no convergence on which option to choose: 
     Option A: Keep 16 HARQ process IDs and rely on RLC ARQ for HARQ processes with UL HARQ feedback disabled via RRC 
     Option B: Greater than 16 HARQ process IDs with UL HARQ feedback enabled via RRC with following consideration. In this case, in the case of 16 or more HARQ process IDs, maintenance of a 4-bit HARQ process ID field in UE capability and DCI may be considered. 
     Alternatively, the following solutions may be considered for 16 or more HARQ processes keeping the 4-bit HARQ process ID field in DCI: 
     Slot number based [62], [67], [68], [60], [69] 
     Virtual process ID based with HARQ re-transmission timing restrictions [61] 
     Reuse HARQ process ID within RTD (time window) [69] 
     Re-interpretation of existing DCI fields with assistance information from higher layers [70] 
     One source also considered solutions where the HARQ process ID field is increased beyond 4 bits [65] 
     With regards to HARQ enhancements for soft buffer management and stop-and-wait time reduction, the following options were considered with no convergence on which, if any, of the options, to choose: 
     Option A-1: Pre-active/pre-emptive HARQ to reduce stop-and-wait time 
     Option A-2: Enabling/disabling of HARQ buffer usage configurable on a per UE and per HARQ process [67], [64], [69] 
     Option A-3: HARQ buffer status report from the UE [67] 
     The number of HARQ processes with additional considerations for HARQ feedback, HARQ buffer size, RLC feedback, and RLC ARQ buffer size should be discussed further when specifications are developed. 
       FIG.  9    is a flowchart illustrating a method for a UE to transmit a UL signal in an NTN according to an embodiment, and  FIG.  10    is a flowchart illustrating a method for a UE to receive a DL signal in an NTN according to an embodiment. 
     At least one of the steps shown in  FIGS.  9  and  10    may be omitted depending on situations or configurations, and the steps shown in  FIGS.  9  and  10    are merely for convenience of explanation and thus do not limit the scope of the present disclosure. 
     Referring to  FIG.  9   , the UE may receive NTN related configuration information and UL data/channel related information (M 31 ). Next, the UE may receive DCI/control information for transmission of UL data/channels (M 33 ). The DCI/control information may include scheduling information for transmission of the UL data/channels. Then, the UE may transmit the UL data/channels based on the scheduling information (M 35 ). The UE may perform UL transmission until all the configured/indicated UL data/channels are transmitted. When all the UL data/channels are transmitted, the UE may terminate the corresponding UL transmission (M 37 ). 
     Referring to  FIG.  10   , the UE may receive NTN related configuration information and DL data/channel related information (M 41 ). Next, the UE may receive DCI/control information for reception of DL data/channels (M 43 ). The DCI/control information may include scheduling information of the DL data/channels. The UE may receive the DL data/channels based on the scheduling information (M 45 ). The UE may receive DL data/channels until all the configured/indicated DL data/channels are received. When all DL data/channels are received, the UE may determine whether feedback information for the received DL data/channels is required (M 47  and M 48 ). If the UE needs to transmit the feedback information, the UE may transmit HARQ-ACK feedback (or HARQ feedback). Otherwise, the UE may terminate the reception operation without transmitting the HARQ-ACK feedback (M 49 ). 
       FIG.  11    is a flowchart illustrating a method for a BS to receive a UL signal in an NTN according to an embodiment, and  FIG.  12    is a flowchart illustrating a method for a BS to transmit a DL signal in an NTN according to an embodiment. At least one of the steps shown in  FIGS.  11  and  12    may be omitted depending on situations or configurations, and the steps shown in  FIGS.  11  and  12    are merely for convenience of explanation and thus do not limit the scope of the present disclosure. 
     Referring to  FIG.  11   , the BS may transmit NTN related configuration information, UL data/channel related information to the UE (M 51 ). Thereafter, the BS may transmit (to the UE) DCI/control information for transmission of UL data and/or UL channels (M 53 ). The DCI/control information may include scheduling information for the UE to transmit the UL data/channels. The BS may receive (from the UE) the UL data/channels transmitted based on the scheduling information (M 55 ). The BS may perform UL reception operation until all the configured/indicated UL data/channels are received. When all the UL data/channels are received, the BS may terminate the corresponding UL reception (M 57 ). 
     Referring to  FIG.  12   , the BS may transmit NTN related configuration information and DL data/channel related information (to the UE) (M 61 ). Thereafter, the BS may transmit (to the UE) DCI/control information for reception of DL data/channels (M 63 ). The DCI/control information may include scheduling information on the DL data/channels. The BS may transmit the DL data/channels (to the UE) based on the scheduling information (M 65 ). The BS may perform DL transmission until all configured/indicated DL data/channels are transmitted. When the BS transmits all DL data/channels, the BS may determine whether the BS needs to receive feedback information for the DL data/channels (M 67  and M 68 ). When the BS needs to receive the feedback information, the BS may receive HARQ-ACK feedback. Otherwise, the BS may terminate the DL transmission without receiving the HARQ-ACK feedback (M 69 ). 
     Embodiments 
     The above contents (e.g., NR frame structure, NTN system, etc.) are applicable in combination with methods proposed in the present disclosure, which will be described later. Alternatively, the contents may clarify the technical features of the methods proposed in the present disclosure. 
     Methods for HARQ disabling/HARQ enhancement, which will be described later, are related to UL signal transmission, and the methods may be equally applied to DL signal transmission in the above-described NR or LTE system. Thus, it is obvious that the terms, expressions, and structures in this document may be modified to be suitable for the above-described system in order to implement the technical idea of the present disclosure in the corresponding system. 
     To guarantee wide coverage or provide wireless communication services in a place where it is not easy to install BSs for wireless communication, it is considered to provide a NR NTN or a LTE NTN. In legacy terrestrial network (TN) services such as NR and LTE services, a BS may be installed on the ground to provide wireless communication services to UEs. Instead of installing BSs on the ground, the NTN provides wireless communication services to UEs by installing BSs on non-terrestrial locations such as satellites (geostationary orbit, low orbit, medium orbit, etc.), airplanes, unmanned aerial vehicles, drones, etc. 
     Frequency bands considered for NR NTN service are a band of 2 GHz (S-band: 2 to 4 GHz) in bands below 6 GHz and a DL band of 20 GHz and a UL band of 30 GHz (Ka-Band: 26.5 to 40 GHz) in bands above 6 GHz. 
     In the worst scenario (GEO scenario A) shown in Table 10 above, the delay may increase up to 540 ms. In this case, a latency problem may occur due to a large delay when the UE performs HARQ feedback. Accordingly, HARQ disabling has been agreed at the recent standardization meeting as follows. 
     
       
         
           
               
             
               
                 TABLE 11 
               
               
                   
               
             
            
               
                 Conclusion 
               
               
                 RAN1 does not need to further discuss dynamic disabling of HARQ by gNB 
               
               
                 following the RAN2#107 decision stating the following 
               
               
                  ● The enabling / disabling of HARQ feedback should be configurable on a 
               
               
                   per UE and per HARQ process basis 
               
               
                   
               
            
           
         
       
     
     Hereinafter, effective HARQ enhancement methods are proposed. 
     Proposal 1. 
     In a system where a relatively large round trip delay (RTD) needs to be considered due to a large distance between the BS and UE such as an NTN, the BS may perform transmission based on PDSCH repetition (or slot aggregation) to improve the link reliability between the BS and UE. The transmission based on PDSCH repetition may mean a method of repeatedly transmitting a PDSCH to improve the link reliability between the BS and UE. In this case, the UE may report/request a minimum slot aggregation level (or recommended repetition number) (required for successful decoding of the PDSCH) to/from the BS. 
     When the UE reports/requests the minimum slot aggregation level or recommended repetition number to/from the BS, the UE may report the minimum slot aggregation level or recommended repetition number to the BS periodically/semi-periodically/aperiodically (e.g., similarly to CSI reporting). Thus, the BS may flexibly manage DL resources, and the UE may effectively manage the buffer. 
     According to the current NR specifications, the BS may semi-statically indicate which aggregation factor (e.g., pdsch-AggregationFactor in pdsch-config) the UE needs to use. If disabling of HARQ feedback is dynamically indicated/configured, repeated transmission of a PDSCH may also be dynamically configured, and an aggregation level may be dynamically indicated to flexibly indicate the PDSCH transmission. The configuration for the PDSCH repetition may be determined implicitly in association with enabling/disabling of HARQ feedback (e.g., in the case of HARQ disabling, the PDSCH repetition may be performed). The configuration for the PDSCH repetition may be explicitly indicated/configured by a separate indicator (e.g., a repetition enabler) in consideration of situations such as data traffic. For dynamic indication of the aggregation level/repetition factor, a separate indicator in a DCI field or time domain resource allocation (TDRA) may be used. When the aggregation level/repetition factor is indicated by the TDRA, the repeated transmission may be performed in slots spaced apart by a step size (e.g., 1, 2, or 4 slots/sub-slots/mini-slots) rather than consecutive slots at the level of the step size as shown in Table 12 for more flexible indication. Additionally/alternatively, a specific repetition pattern may be dynamically indicated. 
     
       
         
           
               
             
               
                 TABLE 12 
               
               
                   
               
             
            
               
                 PDSCH-TimeDomainResourceAllocations-r16 ::= SEQUENCE ( 
               
            
           
           
               
               
            
               
                  k0-r16 
                     INTEGER(0..32) 
               
               
                 OPTIONAL, -- Need S 
               
               
                  mappingType-r16 
                   ENUMERATED (typeA, 
               
               
                 typeB), 
               
               
                  startSymbolAndLength-r16 
                 INTEGER (0..127), 
               
               
                  repetitionNumber-r16 
                  ENUMERATED (n2, n3, 
               
               
                 n4, n5, n6, n7, n8, n16) 
               
               
                 OPTIONAL, -- Cond Formats1-0and1-1 
               
               
                   stepSize 
                   ENUMERATED {n1, n2, 
               
               
                 n4... } 
               
               
                   repetitionPattern 
                    ENUMERATED {type 
               
               
                 A, type B} 
               
               
                  ... 
               
               
                 } 
               
               
                   
               
            
           
         
       
     
     For example, in Proposal 1 described above, HARQ feedback may be configured/indicated only when HARQ feedback is disabled. 
     In current NR, up to 16 HARQ processes may be configured for each UE. In this case, if specific HARQ process IDs among the configured HARQ processes are disabled, the method of configuring a HARQ-ACK codebook may become ambiguous. Hereinafter, methods of effectively configuring a HARQ-ACK codebook when HARQ feedback is disabled will be described. 
     Proposal 2. 
     When HARQ feedback is disabled, the following method of configuring a HARQ-ACK codebook may be considered to reduce unnecessary overhead. Specifically, a method of configuring a HARQ-ACK codebook based on an enabled HARQ process among a plurality of HARQ processes will be described. The HARQ-ACK codebook may be referred to as a HARQ codebook in some embodiments. In addition, the above-described HARQ-ACK codebook determination may be referenced/used perform/understand Proposal 2. 
     1) For Type 1 HARQ-ACK codebook (semi-static HARQ-ACK codebook): 
     If all HARQ process IDs of a specific cell are disabled, the cell may be excluded when the Type 1 HARQ-ACK codebook is configured even though the corresponding cell is a configured cell. In this case, disabling of a HARQ process ID may be used as the same meaning as disabling of a HARQ process. 
     When the Type 1 HARQ-ACK codebook is configured, if only one HARQ process ID is enabled among the HARQ process IDs of a specific cell, a HARQ-ACK bit for one PDSCH may be allocated in the cell, and HARQ feedback for the enabled HARQ process may be performed. 
     If N (e.g., two or more) HARQ process IDs are enabled among the HARQ process IDs of a specific cell, an indicator (e.g., counter-DAI (C-DAI) and total-DAI (T-DAI)) indicating which cell and which HARQ cell the feedback is for may be introduced. 
     The above-described proposal for configuring the Type I HARQ-ACK codebook may be applied/configured only when enabling/disabling of HARQ feedback is semi-statically indicated. 
     The above-described proposal for configuring the Type I HARQ-ACK codebook may be applied/configured limitedly only to cells in which at least one HARQ ID is enabled. 
     When all or some of the HARQ IDs of a specific cell are semi-statically enabled or dynamically enabled/disabled, the corresponding cell may be regarded as a cell in which HARQ feedback is enabled so that the cell may be included in the Type 1 HARQ-ACK codebook configuration. 
     When all of the HARQ IDs of a specific cell are semi-statically disabled, the cell may be considered as a cell in which HARQ feedback is disabled so that the cell may not be included in the Type 1 HARQ-ACK codebook configuration (even though the cell is a configured cell). 
     2) For Type 2 HARQ-ACK codebook (dynamic HARQ-ACK codebook): 
     According to the current NR specifications, for the Type 2 HARQ-ACK codebook, whether the T-DAI field is included in DL DCI may be determined depending on the number of carrier aggregated (CA) cells (i.e., the number of scheduled CCs) (for a single CC, only the C-DAI field exists). Depending on the maximum number of TBs or code block groups (CBGs) configured in each cell (which may be transmitted on a single PDSCH), ACK/NACK granularity (i.e., the number of ACK/NACK bits mapped to each PDSCH) and/or the number of UL DAI fields on the HARK-ACK codebook may be determined. In this case, determining the parameter values by including cells in which HARQ feedback is disabled may cause redundancy to DCI overhead and/or the HARQ-ACK codebook configuration. Therefore, when the HARQ-ACK codebook parameters are configured/determined, only a set of cells in which at least one HARQ process ID is (semi-statically) enabled or (dynamically) enabled may be considered rather than a set of all CA cells. 
     For a cell in which enabling/disabling of HARQ feedback is dynamically indicated, considering the reliability of the HARQ-ACK codebook, the HARQ-ACK codebook may be configured and related parameter values may be determined by regarding the corresponding cell as a cell in which the HARQ feedback is enabled. 
     When HARQ feedback enabling/disabling is configured with the concept of a HARQ process pool (for example, when one pool is a group of disabled HARQ processes and another pool is a group of enabled HARQ processes), the HARQ-ACK codebook may be configured and related parameter values may be determined only for cells including the enabled HARQ process group. 
     For example, a HARQ process pool may mean a set/group/pool of HARQ processes including one or more HARQ process IDs. Enabling/disabling of HARQ feedback may be configured for each HARQ process pool. For example, if a specific HARQ process pool is configured to be enabled, HARQ processes included in the enabled HARQ process pool may be enabled. Then, the HARQ-ACK codebook may be configured and related parameter values may be determined only for cells corresponding to the enabled HARQ process IDs. 
     For example, if one specific HARQ process pool is configured to be disabled only, the other HARQ process pool may comprise HARQ processes which may be enabled. The HARQ-ACK codebook may be configured and related parameter values may be determined only for cells corresponding to the HARQ process IDs included in the pool which may be enabled. 
     3) For Type 3 HARQ-ACK codebook: 
     A Type 3 HARQ-ACK codebook based on HARQ process IDs has been additionally introduced in Rel-16 NR unlicensed bands (NR-U). When HARQ feedback is enabled/disabled (dynamically/semi-statically), it may be more appropriate to use the Type 3 HARQ-ACK codebook based on HARQ process IDs. In this case, similarly to the above proposals, the HARQ-ACK codebook may be configured and related parameter values may be determined only for HARQ process IDs that are enabled or expected to be enabled for each cell. 
     When HARQ feedback enabling/disabling is configured with the concept of a HARQ process pool (for example, when one pool is a group of disabled HARQ processes and another pool is a group of enabled HARQ processes), the HARQ-ACK codebook may be configured and related parameter values may be determined only for cells including the enabled HARQ process group. 
     For example, a HARQ process pool may mean a set/group/pool of HARQ processes with one or more HARQ process IDs. Enabling/disabling of HARQ feedback may be configured for each HARQ process pool. For example, if a specific HARQ process pool is configured to be enabled, HARQ processes included in the corresponding HARQ process pool may be enabled. Then, the HARQ-ACK codebook may be configured and related parameter values may be determined only for cells corresponding to the enabled HARQ process IDs. 
     For example, a HARQ process pool may mean a set/group/pool of HARQ processes with one or more HARQ process IDs. Enabling/disabling of HARQ feedback may be configured for each HARQ process pool. For example, if one specific HARQ process pool is disabled only, the other HARQ process pool may comprise HARQ processes which may be enabled. The HARQ-ACK codebook may be configured and related parameter values may be determined only for cells corresponding to the HARQ process IDs included in the corresponding pool which may be enabled. 
     As one example, when all or some of the HARQ IDs of a specific cell are semi-statically enabled or dynamically enabled/disabled, all HARQ process IDs of the corresponding cell may be included in the Type 3 HARQ-ACK codebook configuration. If all HARQ process IDs of the specific cell are semi-statically disabled, all the HARQ process IDs of the corresponding cell may not be included in the Type 3 HARQ-ACK codebook configuration. 
     As another example, when all or some of the HARQ process IDs of a specific cell are semi-statically enabled or dynamically enabled/disabled, only HARQ process IDs that are (semi-statically) enabled or capable of being (dynamically) enabled in the cell may be included in the Type 3 HARQ-ACK codebook configuration. When all or some of the HARQ process IDs of the specific cell are semi-statically disabled, the disabled HARQ process IDs of the corresponding cell may not be included in the Type 3 HARQ-ACK codebook configuration. 
     For a system in which a large RTT needs to be considered such as the NTN, increasing the number of HARQ processes by effectively using the large RTT is being discussed. In the NTN, the maximum RTT may be regarded as 541.46 ms, 25.77 ms, and 41.77 ms for geostationary earth orbit (GEO), low earth orbit (LEO) (600 km), and LEO (1200 km), respectively. Therefore, the number of HARQ processes may increase in proportion to the RTT in order to effectively use the large RTT. For example, assuming an SCS of 15 kHz, the number of HARQ processes needs to be increase to 542, 26, and 42 for GEO, LEO (600 km), and LEO (1200 km). When the number of HARQ processes increases based on LEO, it may be effective to increase the number of HARQ processes to 24/32/48/64. The BS may configure/indicate the corresponding value based on UE capability reporting. For example, the UE may report the number of supportable HARQ processes (e.g., the maximum number of supportable HARQ processes) to the BS as the UE capability, and the BS may configure the number of HARQ processes to the UE in consideration of the reported UE capability (within the capability of the UE). When the number of HARQ processes increases as described above, there may be a problem in that the size of a HARQ process ID field, which is indicated by (a maximum of) 4 bits of the current DCI field, also needs to increase. For non-fall back DCI, it may be natural to increase the size of the payload (increase the size of the field) (for example, the size increases to 5 or 6 bits), but for fall-back DCI (e.g., DCI 1_0), it may not be desirable to increase the size of the payload in terms of reliability. Therefore, when scheduling is performed with the fall-back DCI, it may be desirable to indicate a maximum of 16 HARQ processes (with up to 4 bits) as in the prior art. 
     When the number of HARQ processes increases, if the size of the HARQ process ID field of DCI is maintained at a maximum of 4 bits as in the prior art with no increase, it is necessary to eliminate ambiguity that is caused by indicating a larger number of HARQ processes with a small number of bits. Hereinafter, a method of solving the above-described problem will be described. 
     Proposal 3. 
     When the number of HARQ processes increases to 16 or more, and when the size of the HARQ process ID field of DCI for indicating an increase in the number of HARQ processes is fixed to 4 bits, a method of identifying each HARQ process ID based on a control channel element (CCE)/resource block (RB) index may be considered. In other words, each HARQ process ID may be identified based on the HARQ process number/ID field and the CCE/RB index of DCI. The CCE/RB may be related to DCI including the HARQ process ID. For example, the CCE/RB may be a CCE in which a PDCCH including the DCI is received or a specific RB of a PDSCH scheduled by the DCI. 
       FIG.  13    is a diagram illustrating a method of identifying a HARQ process based on the lowest CCE index according to a proposed embodiment. 
     As an embodiment according to Proposal 3, when a HARQ process ID is identified based on a (lowest or highest) CCE index, a modulo operation may be performed on the (lowest or highest) CCE index related to DCI indicating a HARQ process, and the result of the modulo operation may be used to identify the HARQ process. For example, when the modulo 2 operation is performed on the (lowest or highest) CCE index, the result of the modulo operation may be 0 or 1, and the result of the modulo operation may be linked with the HARQ process ID field. If the number of HARQ processes increases to 32, 32 HARQ processes may be indicated by ((lowest CCE_index) mod 2)+HARQ process field as shown in  FIG.  13   . In this case, the result of the (CCE index mod 2) operation may be located at the beginning or end of a composite field. When the number of HARQ processes increases to 64, the modulo operation level may increase from 2 to 4, and the above method may be applied as it is by binarizing the result of the modulo operation. For example, when the CCE index is 6, the result of the modulo 4 operation is 2. If 2 is binarized, it becomes 01. As shown in  FIG.  13   , if ‘01’ is located at the beginning or end of composite bits, 64 HARQ processes may be identified. The above-described binarization may vary depending on embodiments. For example, the binarization may be determined as 0: 00/1:01/2:10/3:11. In contrast, the binarization may be determined as 3:00/2:01/1:10/0:11. 
     In Proposal 3, if a HARQ process is identified based on an RB index, a value obtained by the modulo operation on a specific RB index of a PDSCH scheduling by DCI including a HARQ process ID (e.g., lowest RB index or highest RB index) may be located at the beginning or end of composite bits in order to identify the HARQ process. 
     The maximum number of HARQ processes has been agreed at the standardization meeting as shown in Table 13 below. 
     
       
         
           
               
             
               
                 TABLE 13 
               
               
                   
               
             
            
               
                 Agreement: 
               
               
                 The extension of maximal HARQ process number can be considered with following assumptions: 
               
               
                  ● The maximal supported HARQ process number is up to 32. 
               
               
                  ● FFS: Support on the maximal HARQ process number is up to UE capability 
               
               
                 Minimizing the impacts on specification and scheduling 
               
               
                   
               
            
           
         
       
     
     Referring to Table 13, the number of HARQ processes may increase up to 32 in the Rel-17 NTN. In Proposal 3, it is proposed to extend the HARQ process ID field based on an increase in the number of HARQ processes. Accordingly, extending the range of K1 values (e.g., from 0 to 31) may also be considered. Alternatively, in order for the network to fully utilize contiguous DL slots for PDSCH transmission to one or more UEs, that is, for network configuration/scheduling flexibility, it may be considered to extend the range of K1 values. That is, this method may be effectively applied to a plurality of UEs without introducing K_offset that covers the RTD between the UE and BS in an air-to-ground scenario or a high altitude platform station (HAPS) scenario, where K_offset may be an offset different from K1_offset, which will be described later. K_offset has been agreed at the standardization meeting as shown in Table 14 below. 
     
       
         
           
               
             
               
                 TABLE 14 
               
               
                   
               
             
            
               
                 Agreement: 
               
               
                 ● Introduce K_offset to enhance the following timing relationships: 
               
               
                  ◯ The transmission timing of DCI scheduled PUSCH (including CSI on PUSCH). 
               
               
                  ◯ The transmission timing of RAR grant scheduled PUSCH. 
               
               
                  ◯ The transmission timing of HARQ-ACK on PUCCH. 
               
               
                  ◯ The CSI reference resource timing. 
               
               
                  ◯ The transmission timing of aperiodic SRS. 
               
               
                 ● Note: Additional timing relationships that require K_offset of the same or different values can be 
               
               
                  further identified. 
               
               
                   
               
            
           
         
       
     
     In order to effectively support the two use cases, a method of indicating the K1 value will be proposed below. 
     Before description of Proposal 4, the range of K1 values may be determined as follows according to TS 38.213, TS 38.212, etc. For example, the current range of K1 values may be determined based on a PDSCH-to-HARQ_feedback timing indicator field of a higher layer parameter “dl-DataToUL-ACK” (for example, up to 8 values from 0 to 15 of the List of timing for given PDSCH to the DL ACK may be indicated) and/or a PDSCH-to-HARQ_feedback timing indicator field of DCI (the bitwidth of the PDS CH-to-HARQ_feedback timing indicator is determined as ┌ log 2 (I)┐ bits, where I denotes the number of entries included in the high layer parameter dl-DataToUL-ACK). 
     Table 15 below shows a mapping relationship between a PDSCH-to-HARQ_feedback timing indicator field value of DCI and the value of K1 (e.g., the number of slots). 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 15 
               
             
            
               
                   
                   
               
               
                   
                 PDSCH-to-HARQ_ 
                   
               
               
                   
                 feedback timing indicator 
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 1 bit 
                 2 bits 
                 3 bits 
                 Number of slots k 
               
               
                   
                   
               
               
                   
                 ‘0’ 
                 ‘00’ 
                 ‘000’ 
                 1 st  value provided by  
               
               
                   
                   
                   
                   
                 dl-DataToUL-ACK or 
               
               
                   
                   
                   
                   
                 by dl-DataToUL- 
               
               
                   
                   
                   
                   
                 ACKForDCIFormat1_2 
               
               
                   
                 ‘1’ 
                 ‘01’ 
                 ‘001’ 
                 2 nd  value provided by  
               
               
                   
                   
                   
                   
                 dl-DataToUL-ACK or 
               
               
                   
                   
                   
                   
                 by dl-DataToUL- 
               
               
                   
                   
                   
                   
                 ACKForDCIFormat1_2 
               
               
                   
                   
                 ‘10’ 
                 ‘010’ 
                 3 rd  value provided by  
               
               
                   
                   
                   
                   
                 dl-DataToUL-ACK or 
               
               
                   
                   
                   
                   
                 by dl-DataToUL- 
               
               
                   
                   
                   
                   
                 ACKForDCIFormat1_2 
               
               
                   
                   
                 ‘11’ 
                 ‘011’ 
                 4 th  value provided by  
               
               
                   
                   
                   
                   
                 dl-DataToUL-ACK or 
               
               
                   
                   
                   
                   
                 by dl-DataToUL- 
               
               
                   
                   
                   
                   
                 ACKForDCIFormat1_2 
               
               
                   
                   
                   
                 ‘100’ 
                 5 th  value provided by  
               
               
                   
                   
                   
                   
                 dl-DataToUL-ACK or 
               
               
                   
                   
                   
                   
                 by dl-DateToUL- 
               
               
                   
                   
                   
                   
                 ACKForDCIFormat1_2 
               
               
                   
                   
                   
                 ‘101’ 
                 6 th  value provided by  
               
               
                   
                   
                   
                   
                 dl-DataToUL-ACK or 
               
               
                   
                   
                   
                   
                 by dl-DataToUL- 
               
               
                   
                   
                   
                   
                 ACKForDCIFormat1_2 
               
               
                   
                   
                   
                 ‘110’ 
                 7 th  value provided by  
               
               
                   
                   
                   
                   
                 dl-DataToUL-ACK  
               
               
                   
                   
                   
                   
                 or by dl-DataToUL- 
               
               
                   
                   
                   
                   
                 ACKForDCIFormat1_2 
               
               
                   
                   
                   
                 ‘111’ 
                 8 th  value provided by  
               
               
                   
                   
                   
                   
                 dl-DataToUL-ACK or 
               
               
                   
                   
                   
                   
                 by dl-DataToUL-ACK 
               
               
                   
                   
                   
                   
                 ForDCIFormat1_2 
               
               
                   
                   
               
            
           
         
       
     
     Proposal 4. 
     K1 may be indicated by a K1 field of DCI. According to Proposal 4, an extended range of K1 values may be indicated by implicitly adding X bits (e.g., X=1 or 2) while maintaining the current number of bits (e.g., a maximum of 3 bits) without extension of the PDSCH-to-HARQ_feedback timing indicator (e.g., extension to 4 or 5 bits). The implicit indication method may include the following embodiments. 
     1) Alt 1 
     A. In both non-fallback DCI and fallback DCI, K1 offset may be indicated by implicitly adding 1 bit without an increase in the size of the K1 field. In the above example, K1_offset becomes 1. The implicit K1 indication may be determined based on a slot index or system frame number (SFN). For example, in the case of an even slot index, the K1_offset value may be determined to be 0, and in the case of an odd slot index, the K1_offset value may be determined to be 1. In other words, the K1 value may be determined based on a value indicated by bits obtained by combining the bits of the K1 field and the implicit K1_offset indication. 
     B. As another embodiment of Alt 1, the K1 value may be determined based on the lowest/highest CCE index of a PDCCH carrying DCI or the lowest/highest index of a PDSCH scheduled by the corresponding DCI as in Proposal 3. That is, K1_offset may correspond to i) the lowest/highest CCE index of the PDCCH carrying the DCI or ii) the lowest/highest index of the PDSCH scheduled by the corresponding DCI in Proposal 3 described above. In this case, the slot index may be a slot index in which the PDCCH carrying the corresponding DCI is detected or a specific index of the PDSCH scheduled by the DCI (e.g., the starting index of the PDSCH). 
     C. In Case A, an implicitly obtained 1 bit may be finally located as the LSB when K1 is indicated. That is, Case A corresponds to the second case shown in  FIG.  13   . Similarly, a case in which an implicit 1 bit is located as the MSB may also be considered as shown in the first case of  FIG.  13   . In this case, K1 offset becomes 16. That is, when the slot index is from 0 to 15, K1 offset is 0, and when the slot index is from 16 to 31, K1_offset is 16. The aforementioned K1_offset value is an example of when there are 32 HARQ processes, and the K1_offset value may vary as the number of candidate K1 values increases or the number of HARQ processes increases. Alternatively, the K1_offset value may be a value configured by the BS or a value previously agreed between the BS and UE. 
     2) Alt 2 
     For non-fallback DCI, the size of a K field may increase (e.g., the size may increase to 5 bits). However, for fallback DCI, an implicit K offset may be applied without increasing the size of the K1 field. In this case, the implicit K offset may be applied according to Alt 1. 
     3) Alt 3 
     For both non-fallback DCI and fallback DCI, the size of the K field may not increase. However, an implicit K1 offset may be applied for non-fallback DCI, but no implicit K1 offset may be applied for fallback DCI. Only a value indicated by the K1 field (e.g., 3 bits) may be used as in the prior art. In this case, the implicit K1 offset may be applied according to Alt 1. 
     In Proposal 4, an implicit indicator may be used to indicate K1. However, the implicit indicator may be used to indicate a HARQ process ID as in Proposal 3. Accordingly, the implicit indicator may be commonly applied to indicate the HARQ process ID and K1. That is, one implicit bit (one bit obtained according to Proposal 4 above) may be located as the MSB or LSB to indicate the HARQ process ID and K1. Alternatively, in another embodiment, the HARQ process ID and K1 may be indicated by increasing the modulo operation level in the implicit method of Proposal 3 or 4. For example, values of 0, 1, 2, and 3 may be obtained by applying the modulo 4 operation to the slot index rather than the modulo 2 operation, and the obtained value may be jointly used to indicate the HARQ process ID and K1. For example, referring to Table 16, 0, 1, 2, and 3 obtained by applying the modulo 4 operation to the slot index may be binarized, and the MSB/LSB of the binarized bits may be mapped to the HARQ process ID and K1 indicator, respectively (and vice versa) in order to indicate the HARQ process ID and K1. 
     
       
         
           
               
               
               
             
               
                 TABLE 16 
               
               
                   
               
               
                   
                 HARQ  
                 K1 indicator 
               
               
                   
                 process id 
                 (or HARQ  
               
               
                   
                 (or K1 indicator) 
                 process id) 
               
               
                   
               
             
            
               
                 0 (00) 
                 0 
                 0 
               
               
                 1 (01) 
                 0 
                 1 
               
               
                 2 (10) 
                 1 
                 0 
               
               
                 3 (11) 
                 1 
                 1 
               
               
                   
               
            
           
         
       
     
     When the HARQ process ID and K1 are commonly indicated, a 1-bit or 2-bit combination indicator may be separately defined within the DCI field, and the combination indicator may be combined with one or more specified fields. In this case, all or some of the bits of the combination indicator may be located as the MSB or LSB of the last indication bits (e.g., 5 bits of K1 or HARQ process ID indicator) (in some cases, as shown in Table 15). For example, a 1-bit indicator may be defined and used in common for the K1 field and/or the HARQ process ID field. In addition, the 1-bit indicator may be located as the MSB or LSB. 
     HARQ codebook enhancement has been agreed at the standardization meeting as shown in Table 17 below. 
     
       
         
           
               
             
               
                 TABLE 17 
               
               
                   
               
             
            
               
                 Agreement: 
               
               
                 HARQ codebook enhancement is supported as: 
               
               
                  ● For Type-2 HARQ codebook: 
               
               
                   ◯ Option-1: Reduce codebook size with: 
               
               
                    ▪ HARQ-ACK codebook only includes HARQ-ACK of PDSCH 
               
               
                     with feedback-enabled HARQ processes 
               
               
                      ● FFS: the details of C-DAI and T-DAI counting for DCI of 
               
               
                       PDSCH with feedback-enable/disabled. HARQ processes 
               
               
                    ▪ FFS: at least DCI for SPS release/SPS PDSCH 
               
               
                   ◯ Option-2: No enhancement 
               
               
                   ◯ Other options are not precluded. 
               
               
                   
               
            
           
         
       
     
     In the Type 1, 2, and 3 HARQ-ACK codebooks, when DCI scheduling a PDSCH indicates a disabled HARQ process, even if a specific field (e.g., K1, PUCCH Resource Indicator (PRI), etc.) exists, the UE may not read the field (or may ignore the field). Alternatively, when the disabled HARQ process is indicated, compact DCI may be configured without the specific field. If the HARQ-ACK codebook configuration consists of only enabled HARQ processes, the ACK/NACK for a disabled HARQ process may be excluded from the codebook configuration. For the legacy Type 1 HARQ-ACK codebook, the size of the semi-statically set codebook may be determined (including disabled HARQ processes). The HARQ-ACK for the disabled HARQ process may be reported as a NACK because there is no information about the parameter (K1 and PRI) and/or start and length indicator value (SLIV) related to HARQ feedback in DCI. 
     In particular, various candidates have been discussed for the Type 2 HARQ codebook. Table 18 below shows the candidates discussed. 
     
       
         
           
               
             
               
                 TABLE 18 
               
               
                   
               
             
            
               
                  1) Alt-1: C-DAT and T-DAT count only PDSCH with feedback-enabled HARQ 
               
               
                 processes. 
               
               
                  - In the DCI of PDSCH with feedback-enabled HARQ processes, the C-DAI 
               
               
                 and T-DAI are given their true values (i.e., the count of feedback-enabled 
               
               
                 processes) 
               
               
                  In the DCI of PDSCH with feedback disabled HARQ processes, the C DAI 
               
               
                 and T-DAI are given their true values (i.e., the count of feedback-enabled 
               
               
                 processes), despite they are not incremented. 
               
               
                  2) Alt-2: C-DAI and T-DAI count only PDSCH with feedback-enabled HARQ 
               
               
                 processes. 
               
               
                  - In the DCI of PDSCH with feedback-enabled HARQ processes, the C-DAI 
               
               
                 and T-DAI are given their true values (i.e., the count of feedback-enabled 
               
               
                 processes) 
               
               
                  - In the DCI of PDSCH with feedback-disabled HARQ processes, the C-DAI 
               
               
                 and T-DAI are given a reserved value that was be ignored by the UE 
               
               
                  3) Alt-3: HARQ-ACK codebook only includes HARQ-ACK of enabled PDSCH 
               
               
                  - C-DAI/T-DAI value in DCI scheduling enabled PDSCH is counted for 
               
               
                 enabled PDSCH 
               
               
                  - C-DAI/T-DAI value in DCI scheduling disabled PDSCH is counted for 
               
               
                 disabled PDSCH 
               
               
                  4) Alt-4: C-DAI and T-DAI count only PDSCH with feedback-enabled HARQ 
               
               
                 processes. 
               
               
                  - In the DCI of PDSCH with feedback-enabled HARQ processes, the C-DAI 
               
               
                 and T-DAI are given their true values (i.e., the count of feedback-enabled 
               
               
                 processes) 
               
               
                  5) Alt-5: Other alternatives are not precluded 
               
               
                   
               
            
           
         
       
     
     If a disabled HARQ process ID is first configured/indicated for the Type 2 HARQ-ACK codebook as in Alt 1 among the alternatives, or if the HARQ-ACK codebook consists of only disabled HARQ process IDs, the UE may have ambiguity in receiving/interpreting the C-DAI and t-DAI. Hereinafter, a method of solving the above-described problem will be described. 
     Proposal 5. 
     When HARQ feedback includes a disabled HARQ process ID, and more particularly, when the disabled HARQ process ID is configured first or when only the disabled HARQ process ID is configured, the UE may operate according to the following embodiment. 
     1) The UE may not read or may ignore the C-DAI value of DCI scheduled for the disabled HARQ process ID. When the UE configures a HARQ-ACK codebook, the UE may omit the ACK/NACK feedback on the disabled HARQ process ID. 
     2) The UE may read the C-DAI value of the DCI scheduled for the disabled HARQ process ID. 
     A. The initial value of the C-DAI may be set to 0 (considering the modular operation (2 bits→&gt;modulo 4), the C-DAI may be indicated as 4 by the DCI field.) 
     For example, if DCI with a C-DAI value of 4 is received, and if there is an enabled HARQ process ID received before the reception of the DCI, the UE may interpret the C-DAI value as 4. If there is no enabled HARQ process ID received before the reception of the DCI, the UE may interpret the C-DAI value as 0 and omit the ACK/NACK feedback on the corresponding HARQ process ID. 
     If HARQ process IDs configured/indicated for the Type 2 HARQ-ACK codebook starts with a disabled HARQ process ID, the UE may interpret the C-DAI value as 0. For example, if enabling/disabling of HARQ feedback for 7 HARQ process IDs indicated for the Type 2 HARQ-ACK codebook is set to {disabled, disabled, disabled, enabled, enabled, disabled, disabled}, the UE may interpret the C-DAI value as 0-0-0-1-2-2-2. 
     B. When the initial value of the C-DAI is set to 1, and when the T-DAI value is 1 because the UE receives only a disabled HARQ process ID, the UE may omit ACK/NACK feedback. 
     For example, when the UE receives HARQ process IDs set to {disabled, disabled, disabled}, that is, when the C-DAI value is {1, 1, 1} and the T-DAI value is 1, the UE may omit ACK/NACK feedback for the corresponding Type 2 HARQ-ACK codebook because there is no received enabled HARQ process ID. 
     Alternatively, when the UE receives HARQ process IDs set to {disabled, disabled, enabled}, that is, when the C-DAI value is {1, 1, 1} and the T-DAI value is 1, the UE may set the ACK/NACK codebook size of the Type 2 HARQ-ACK codebook to 1 bit and report the ACK/NACK codebook size to the BS because an enabled HARQ process ID is received 
     C. When HARQ process IDs starts with an enabled HARQ process ID, the UE may set the C-DAI value to 2. When HARQ process IDs starts with a disabled HARQ process ID, the UE may set the C-DAI value to 1 or invalid. Then, the UE may configure the Type 2 HARQ-ACK codebook by setting the size of the final codebook to (T-DAI value)-1 and perform feedback to the BS. 
     D. When the UE receives only a disabled HARQ process ID, but when the C-DAI/T-DAI value is not the initial value (e.g., 2), the UE may omit ACK/NACK feedback based on the Type 2 HARQ-ACK codebook. 
     Alternatively, the UE may report a NACK for the codebook size corresponding to the T-DAI value (i.e., 2-bit codebook in the above embodiment) to the BS. In the above embodiment, the UE may report {NACK, NACK} to the BS. 
     E. For the C-DAI value of a disabled HARQ process ID, the last C-DAI value of a “signaled” enabled HARQ process ID may be maintained. In this case, if there is no enabled HARQ process ID scheduled, the UE may ignore the C-DAI in DCI scheduling the disabled HARQ process ID. Therefore, since there is no valid C-DAI, the UE may omit ACK/NACK feedback therefor. 
     In the above example of {disabled, disabled, disabled, enabled, enabled, disabled, disabled}, the UE may interpret the C-DAI value configured/indicated by the BS as invalid-invalid-invalid-1-2-2-2. 
     For a UL-DAI indicated by a DAI field in a UL grant PDCCH (information on the number of scheduled PDCCHs indicated by 2 bits), the principle of Proposal 5 may be equally applied. For example, when the UE receives DL DCI scheduling a DL signal, but when all HARQ process IDs are disabled or when the UE does not receive DL DCI related to enabled HARQ process IDs, if a UL-DAI value indicated by the UL grant PDCCH is 4, 0, or invalid, the UE may not perform HARQ feedback. Specifically, when a PUCCH resource for HARQ feedback overlaps with a PUSCH resource in the time domain, the corresponding PUCCH resource may be piggybacked on the PUSCH resource. In this case, if the UL-DAI value is 4, 0, or invalid, the UE may not piggyback HARQ-ACK information on the PUSCH. 
     (In Proposal 2 and/or 4 above), a PUCCH resource used for HARQ-ACK transmission in a specific slot may be determined based on a PRI indicated by the last received DCI among DCIS indicating the corresponding slot as the HARQ-ACK timing (K1) and enabled HARQ process IDs. 
       FIG.  14    is a flowchart illustrating operations of a UE according to proposed embodiments. 
     Referring to  FIG.  14   , the UE may receive control information for disabling at least one of a plurality of HARQ processes according to an embodiment (S 1400 ). In the NTN, HARQ-ACK feedback may be disabled in order to solve a latency problem due to a relatively large RTT (or RTD). In this case, at least one of a plurality of HARQ processes configured for HARQ-ACK feedback may be disabled, and disabling of the at least one HARQ process may be configured semi-statically or dynamically. 
     The UE may receive a DL signal based on the control information (S 1410 ). In general, the UE may perform HARQ-ACK feedback for the received DL signal. However, when the at least one HARQ process is disabled, the HARQ-ACK feedback may be performed differently. Specifically, a HARQ-ACK codebook may be determined differently from a case in which the plurality of HARQ processes are all enabled. For example, the HARQ-ACK codebook may be determined based on enabled HARQ processes rather than all of the plurality of HARQ processes. In addition, the at least one disabled HARQ process may be excluded from determination of the HARQ-ACK codebook. In this case, the enabled HARQ processes may be determined based on the control information for disabling the at least one HARQ process among the plurality of HARQ processes. For example, the enabled HARQ processes may include the remaining HARQ processes except for the at least one HARQ process disabled based on the control information among the plurality of HARQ processes. For example, the UE may ignore a C-DAI value in DCI indicating the at least one disabled HARQ process. 
     The UE may determine whether to perform the HARQ-ACK feedback for the received DL signal based on the determined HARQ-ACK codebook (S 1420 ). 
     When the UE is configured with a plurality of cells, a plurality of HARQ processes may be configured for each of the plurality of cells. In this case, the control information for disabling the at least one of the plurality of HARQ processes may be control information for disabling at least one of a plurality of HARQ processes configured for a specific cell. For example, when the plurality of HARQ processes configured for the specific cell are all disabled, the UE may determine the HARQ-ACK codebook by excluding the corresponding cell. In other words, the HARQ-ACK codebook may be determined based on cells in which at least one HARQ process is enabled. Alternatively, when only one of the plurality of HARQ processes configured for the specific cell is enabled, HARQ-ACK bit(s) for one DL signal (e.g., PDSCH) may be allocated in the corresponding cell, and the HARQ-ACK feedback may be performed for the enabled HARQ process. 
     As described above, considering that the UE requires a time for processing the received DL signal when performing the HARQ-ACK feedback, a timing offset (e.g., “PDSCH-to-HARQ feedback timing indicator”) for performing the HARQ-ACK feedback may be configured. In the NTN, the number of HARQ processes may increase in consideration of the relatively large RTT, and thus, the range of the timing offset value may extend. When the range of the timing offset value extends, a method of indicating the extended range of the timing offset value is needed. The timing offset value may be indicated to the UE by a specific field (e.g., K1 field) of DCI. However, when the range of the timing offset value extends, a larger number of bits than before may be required to indicate the extended range of the timing offset value. In the case of fallback DCI, it may not be easy to increase the size of the specific field. According to the proposed embodiment, a value determined based on a resource index may be used in addition to the specific field of the DCI. The value determined based on the resource index may correspond to the implicit K1 indicator in Proposal 4 described above. In this case, the resource index may include a CCE index in which a PDCCH including the DCI is transmitted, a slot index in which the PDCCH is detected, or an RB index in which a PDSCH scheduled by the DCI is transmitted, but the present disclosure is not limited thereto. For example, the CCE index in which the PDCCH is transmitted may mean the lowest or highest index among CCE indices in which the PDCCH is transmitted, and the RB index in which the PDSCH is transmitted may mean the starting RB index among RB indices in which the PDSCH is transmitted. However, the present disclosure is not limited thereto. 
     The value determined based on the resource index may be implicitly used as an additionally necessary bit for indicating the extended range of the timing offset. For example, when a slot index is used, the value determined based on the resource index may be ‘0’ in the case of an even slot index or ‘1’ in the case of an odd slot index, but the present disclosure is not limited thereto. 
     According to the proposed embodiments, when the HARQ-ACK feedback is disabled, the HARQ-ACK codebook may be configured more efficiently, thereby reducing unnecessary overhead. In addition, according to the proposed embodiments, in the NTN, when the number of HARQ processes increases or when the range of a timing offset value for performing HARQ-ACK feedback extends, an increase in the number of HARQ processes or the timing offset value may be indicated implicitly without increasing the size of a DCI field. 
     It is obvious that each of the examples of the proposed methods may also be included as one implementation method, and thus each of the examples may be regarded as a kind of proposed method. Although the proposed methods may be implemented independently, some of the proposed methods may be combined (or merged) for implementation. In addition, it may be regulated that information on whether the proposed methods are applied (or information on rules related to the proposed methods) should be transmitted from the BS to the UE in a predefined signal (e.g., a physical layer signal, a higher layer signal, etc.). Higher layers may include, for example, at least one of the following functional layers: MAC, RLC, PDCP, RRC, and SDAP. 
     Methods, embodiments, or details for implementing the methods proposed in this specification (e.g., Proposal 1, Proposal 2, Proposal 3, Proposal 4, and Proposal 5) may be applied independently. Alternatively, at least one of the methods (embodiments or details) may be applied in combination. 
       FIG.  15    is a flowchart illustrating operations of transmitting and receiving a UL signal between a BS and a UE according to the proposed embodiments, and  FIG.  16    is a flowchart illustrating operations of transmitting and receiving a DL signal between a BS and a UE according to the proposed embodiments. 
     Here, the UE and BS are merely examples, and the UE and BS may be replaced with various devices. In addition,  FIGS.  15  and  16    are only for convenience of description, and the scope of the present disclosure is not limited to  FIGS.  15  and  16   . Some of the steps shown in  FIGS.  15  and  16    may be omitted/merged depending on situations and/or configurations. 
     In this document, the BS may refer to an object that performs data transmission/reception with the UE. For example, the BS may conceptually include one or more transmission points (TPs), one or more transmission and reception points (TRPs), and the like. The TP and/or TRP may include a panel or a transmission and reception unit of the BS. In addition, the term “TRP” may be replaced with the following terms: panel, antenna array, cell (e.g., macro cell, small cell, pico cell, etc.), TP, and BS (gNB, etc.). As described above, the TRP may be identified based on information (e.g., index or ID) on a CORESET group (or CORESET pool). For example, when one UE is configured to perform transmission and reception with a plurality of TRPs (or cells), it may mean that a plurality of CORESET groups (or CORESET pools) are configured for the UE. The configuration of the CORESET group (or CORESET pool) may be performed through higher layer signaling (e.g., RRC signaling, etc.). 
     Hereinafter, a UL signal transmission/reception operation between the UE and BS will be described in detail with reference to  FIG.  15   . 
     Although not shown in  FIG.  15   , a default HARQ operation mode of the UE may be configured in a step before the RRC connection/configuration as described in the proposed methods (e.g., Proposal 1, Proposal 2, Proposal 3, Proposal 4, and Proposal 5). For example, if the cell accessed by the UE is indicated as an NTN cell over a PBCH (MIB) or an SIB, the UE may recognize that the default mode is set to a HARQ-disabled mode. For example, one of a HARQ-disabled configuration and HARQ-enabled configuration(s) may be indicated as the default operation mode over the PBCH (MIB) or SIB (for example, when the cell is indicated as the NTN cell). 
     In addition, although not shown in  FIG.  15   , the UE may report to the BS information on UE capability related to the proposed methods (e.g., Proposal 1, Proposal 2, Proposal 3, Proposal 4, and Proposal 5). For example, the UE capability information may include information on the number of times of channel (e.g., PDSCH) repetitions supportable/recommended for the UE, information on a slot aggregation level, and/or information on the number of supported HARQ processes. For example, the UE capability information may be reported periodically/semi-persistently/aperiodically. The BS may configure/indicate the operations to be described below in consideration of the UE capability. 
     The BS may transmit configuration information to the UE (M 105 ). That is, the UE may receive the configuration information from the BS. For example, the configuration information may include: NTN related configuration information described in the proposed methods (e.g., Proposal 1, Proposal 2, Proposal 3, Proposal 4, and Proposal 5); configuration information for UL transmission and reception (e.g., PUCCH-config, PUSCH-config, etc.); HARQ process related configurations (e.g., enabling/disabling of HARQ feedback, the number of HARQ processes, etc.); and/or CSI report related configurations (e.g., CSI report config, CSI report quantity, CSI-RS resource config, etc.). For example, the configuration information may be transmitted through higher layer signaling (RRC or MAC CE). For example, the HARQ feedback enabling/disabling may be configured for each cell group. For example, the HARQ feedback enabling/disabling may be configured by information in the form of a bitmap. 
     For example, the configuration information may include an aggregation factor and/or a PDSCH repetition related configuration (e.g., the number of repetitions, a repetition pattern, a repetition step size, etc.). For example, the operation in which the BS ( 100 / 200  in  FIG.  18   ) transmits the configuration information to the UE ( 100 / 200  in  FIGS.  18  to  20   ) in step M 105  may be performed by devices of  FIGS.  18  to  20   , which will be described later. For example, referring to  FIG.  18   , one or more processors  102  may control one or more transceivers  106  and/or one or more memories  104  to transmit the configuration information, and the one or more transceivers  106  may transmit the configuration information to the UE. 
     For example, the operation in which the UE ( 100 / 200  in  FIG.  18   ) receives the configuration information from the BS ( 100 / 200  in  FIG.  18   ) in step M 105  may be performed by the devices of  FIGS.  18  to  20    to be described below. For example, referring to  FIG.  18   , the one or more processors  102  may control the one or more transceivers  106  and/or one or more memories  104  to receive the configuration information, and the one or more transceivers  106  may receive the configuration information from the BS. 
     The BS may transmit the configuration information to the UE (M 110 ). That is, the UE may receive the configuration information from the BS. For example, the configuration information may be transmitted/received in DCI. For example, the configuration information may include UL data, control information for channel transmission/reception, scheduling information, resource allocation information, and HARQ feedback related information (e.g., a new data indicator (NDI), a redundancy version (RV), the number of HARQ processes, a downlink assignment index (DAI), a transmit power control (TPC) command for a scheduled PUCCH, a PUCCH resource indicator, a PDSCH-to-HARQ feedback timing indicator, etc.). For example, the DCI may be one of DCI format 1_0 or DCI format 1_1. 
     For example, whether the HARQ feedback is enabled or disabled may be configured based on the DCI. For example, whether the HARQ feedback is enabled or disabled may be configured based on the PDSCH-to-HARQ_feedback timing indicator field and/or PUCCH resource indicator field of the DCI. For example, the DCI may include an aggregation level (and/or repetition factor). For example, the number of HARQ processes may be set to 16 or more, and the 16 or more HARQ process IDs may be identified based on the HARQ process number field of the DCI and the index of a CCE/RB associated with the DCI. 
     For example, the operation in which the BS ( 100 / 200  in  FIG.  18   ) transmits the configuration information to the UE ( 100 / 200  in  FIG.  18   ) in step M 110  may be performed by the devices of  FIGS.  18  to  20    to be described below. For example, referring to  FIG.  18   , the one or more processors  102  may control the one or more transceivers  106  and/or one or more memories  104  to transmit the configuration information, and the one or more transceivers  106  may transmit the configuration information to the UE. 
     For example, the operation in which the UE ( 100 / 200  in  FIG.  18   ) receives the configuration information from the BS ( 100 / 200  in  FIG.  18   ) in step M 110  may be performed by the devices of  FIGS.  18  to  20    to be described below. For example, referring to  FIG.  18   , the one or more processors  102  may control the one or more transceivers  106  and/or one or more memories  104  to receive the configuration information, and the one or more transceivers  106  may receive the configuration information from the BS. 
     The BS may receive UL data/channels (e.g., PUCCH/PUSCH) from the UE (M 115 ). That is, the UE may transmit the UL data/channels to the BS. For example, the UL data/channels may be received/transmitted based on the aforementioned configuration information/control information. For example, the UL data/channels may be received/transmitted according to the proposed method (e.g., Proposal 1, Proposal 2, Proposal 3, and Proposal 4). For example, CSI reporting may be performed over the UL data/channels. The CSI reporting may include transmitting information such as RSRP/CQI/SINR/CRI to the BS. For example, the UL data/channels may include a UE request/report related to the HARQ feedback enabling/disabling. For example, as described in the proposed methods, the UE may report/request the HARQ feedback enabling/disabling based on a report on an increase/decrease in the MCS and a report on an increase/decrease in the number of PDSCH repetitions. For example, the UL data/channels may include HARQ-ACK information. For example, a HARQ-ACK codebook (e.g., Type 1/2/3) may be configured according to Proposal 2 described above. For example, when the HARQ-ACK information is transmitted over the UL data/channels, a timing for transmitting the HARQ-ACK information may be determined according to Proposal 4 described above. 
     For example, the operation in which the BS ( 100 / 200  in  FIG.  18   ) receives the UL data/channels from the UE ( 100 / 200  in  FIGS.  18  to  20   ) in step M 115  may be performed by the devices shown in  FIGS.  18  to  20    to be described below. For example, referring to  FIG.  18   , the one or more processors  102  may control the one or more transceivers  106  and/or one or more memories  104  to receive the UL data/channels, and the one or more transceivers  106  may receive the UL data/channels from the UE. 
     For example, the operation in which the UE ( 100 / 200  in  FIG.  18   ) transmits the UL data/channels to the BS ( 100 / 200  in  FIGS.  18  to  20   ) in step M 115  may be performed by the devices shown in  FIGS.  18  to  20    to be described below. For example, referring to  FIG.  18   , the one or more processors  102  may control the one or more transceivers  106  and/or one or more memories  104  to transmit the UL data/channels, and the one or more transceivers  106  may transmit the UL data/channels to the BS. 
     Hereinafter, a DL data/channel transmission/reception operation between the UE and BS according to an embodiment will be described in detail with reference to  FIG.  16   . 
     Although not shown in  FIG.  16   , a default HARQ operation mode of the UE may be configured in a step before the RRC connection/configuration as described in the proposed methods (e.g., Proposal 1, Proposal 2, Proposal 3, Proposal 4, and Proposal 5). For example, if the cell accessed by the UE is indicated as an NTN cell over a PBCH (MIB) or an SIB, the UE may recognize that the default mode is set to a HARQ-disabled mode. For example, the BS may indicate one of a HARQ-disabled configuration and HARQ-enabled configuration(s) as the default operation mode over the PBCH (MIB) or SIB (for example, when the cell is indicated as the NTN cell). 
     In addition, although not shown in  FIG.  16   , the UE may report to the BS information on UE capability related to the proposed methods (e.g., Proposal 1, Proposal 2, Proposal 3, Proposal 4, and Proposal 5). For example, the UE capability information may include information on the number of times of channel (e.g., PDSCH) repetitions supportable/recommended for the UE, information on a slot aggregation level, and/or information on the number of supported HARQ processes. For example, the UE capability information may be reported periodically/semi-persistently/aperiodically. The BS may configure/indicate the operations to be described below in consideration of the UE capability. 
     The BS may transmit configuration information to the UE (M 205 ). That is, the UE may receive the configuration information from the BS. For example, the configuration information may include: NTN related configuration information described in the proposed methods (e.g., Proposal 1, Proposal 2, Proposal 3, Proposal 4, and Proposal 5); configuration information for DL transmission and reception (e.g., PDCCH-config, PDSCH-config, etc.); HARQ process related configurations (e.g., enabling/disabling of HARQ feedback, the number of HARQ processes, etc.); and/or CSI report related configurations (e.g., CSI report config, CSI report quantity, CSI-RS resource config, etc.). For example, the configuration information may be transmitted through higher layer signaling (RRC or MAC CE). For example, the HARQ feedback enabling/disabling may be configured for each cell group. For example, the HARQ feedback enabling/disabling may be configured by information in the form of a bitmap. For example, the configuration information may include an aggregation factor, a PDSCH repetition related configuration (e.g., the number of repetitions, a repetition pattern, a repetition step size, etc.). For example, the configuration information may include a parameter dl-DataToUL-ACK. For example, multiple integers from 0 to 31 may be indicated based on the parameter dl-DataToUL-ACK. 
     For example, the operation in which the BS ( 100 / 200  in  FIG.  18   ) transmits the configuration information to the UE ( 100 / 200  in  FIGS.  18  to  20   ) in step M 205  may be performed by the devices of  FIGS.  18  to  20   , which will be described later. For example, referring to  FIG.  18   , the one or more processors  102  may control the one or more transceivers  106  and/or one or more memories  104  to transmit the configuration information, and the one or more transceivers  106  may transmit the configuration information to the UE. 
     For example, the operation in which the UE ( 100 / 200  in  FIG.  18   ) receives the configuration information from the BS ( 100 / 200  in  FIGS.  18  to  20   ) in step M 205  may be performed by the devices of  FIGS.  18  to  20    to be described below. For example, referring to  FIG.  18   , the one or more processors  102  may control the one or more transceivers  106  and/or one or more memories  104  to receive the configuration information, and the one or more transceivers  106  may receive the configuration information from the BS. 
     The BS may transmit control information to the UE (M 210 ). That is, the UE may receive the control information from the BS. For example, the control information may be transmitted/received in DCI. For example, the control information may include control information for transmission and reception of DL data/channels, scheduling information, resource allocation information, HARQ feedback related information (e.g., an NDI, an RV, the number of HARQ processes, a DAI, a TPC command for a scheduled PUCCH, a PUCCH resource indicator, a PDSCH-to-HARQ_feedback timing indicator, etc.). For example, the DCI may be one of DCI format 1_0 or DCI format 1_1. 
     For example, whether the HARQ feedback is enabled or disabled may be configured based on the DCI as described in the proposed methods (e.g., Proposal 1, Proposal 2, Proposal 3, Proposal 4, and Proposal 5). For example, whether the HARQ feedback is enabled or disabled may be configured based on the PDSCH-to-HARQ_feedback timing indicator field and/or PUCCH resource indicator field of the DCI. For example, the DCI may include an aggregation level (and/or repetition factor). For example, the number of HARQ processes may be set to 16 or more, and the 16 or more HARQ process IDs may be identified based on the HARQ process number field of the DCI and the index of a CCE/RB associated with the DCI. 
     For example, the operation in which the BS ( 100 / 200  in  FIG.  18   ) transmits the control information to the UE ( 100 / 200  in  FIGS.  18  to  20   ) in step M 210  may be performed by the devices of  FIGS.  18  to  20    to be described below. For example, referring to  FIG.  18   , the one or more processors  102  may control the one or more transceivers  106  and/or one or more memories  104  to transmit the control information, and the one or more transceivers  106  may transmit the control information to the UE. 
     For example, the operation in which the UE ( 100 / 200  in  FIG.  18   ) receives the control information from the BS ( 100 / 200  in  FIGS.  18  to  20   ) in step M 210  may be performed by the devices of  FIGS.  18  to  20    to be described below. For example, referring to  FIG.  18   , the one or more processors  102  may control the one or more transceivers  106  and/or one or more memories  104  to receive the control information, and the one or more transceivers  106  may receive the control information from the BS. 
     The BS may transmit DL data/channels (e.g., PDSCH) to the UE (M 215 ). That is, the UE may receive the DL data/channels from the BS. For example, the DL data/channels may be transmitted/received based on the aforementioned configuration information/control information. For example, the DL data/channels may be repeatedly transmitted/received (e.g., based on slot aggregation). 
     For example, the operation in which the BS ( 100 / 200  in  FIG.  18   ) transmits the DL data/channels to the UE ( 100 / 200  in  FIGS.  18  to  20   ) in step M 215  may be performed by the devices shown in  FIGS.  18  to  20    to be described below. For example, referring to  FIG.  18   , the one or more processors  102  may control the one or more transceivers  106  and/or one or more memories  104  to transmit the DL data/channels, and the one or more transceivers  106  may transmit the DL data/channels to the UE. 
     For example, the operation in which the UE ( 100 / 200  in  FIG.  18   ) receives the DL data/channels from the BS ( 100 / 200  in  FIGS.  18  to  20   ) in step M 115  may be performed by the devices shown in  FIGS.  18  to  20    to be described below. For example, referring to  FIG.  18   , the one or more processors  102  may control the one or more transceivers  106  and/or one or more memories  104  to receive the DL data/channels, and the one or more transceivers  106  may receive the DL data/channels from the BS. 
     The BS may receive HARQ-ACK feedback from the UE (M 220 ). That is, the UE may transmit the HARQ-ACK feedback to the BS. For example, the HARQ-ACK feedback may be enabled/disabled according to the proposed methods (e.g., Proposal 1, Proposal 2, Proposal 3, Proposal 4, and Proposal 5). For example, when the HARQ-ACK feedback is enabled, the HARQ-ACK feedback may be transmitted/received according to the proposed methods (e.g., Proposal 1, Proposal 2, Proposal 3, Proposal 4, and Proposal 5). For example, the HARQ-ACK feedback may include ACK/NACK information for DL data/channels transmitted from the BS. For example, the HARQ-ACK feedback may be transmitted on a PUCCH and/or PUSCH. For example, a HARQ-ACK codebook (e.g., Type 1/2/3) may be configured according to Proposal 2 described above. For example, a timing for transmitting the HARQ-ACK feedback may be determined according to Proposal 4 described above. 
     For example, the operation in which the BS ( 100 / 200  in  FIG.  18   ) receives the HARQ-ACK feedback from the UE ( 100 / 200  in  FIGS.  18  to  20   ) in step M 220  may be performed by the devices shown in  FIGS.  18  to  20    to be described below. For example, referring to  FIG.  18   , the one or more processors  102  may control the one or more transceivers  106  and/or one or more memories  104  to receive the HARQ-ACK feedback, and the one or more transceivers  106  may receive the HARQ-ACK feedback from the UE. 
     For example, the operation in which the UE ( 100 / 200  in  FIG.  18   ) transmits the HARQ-ACK feedback to the BS ( 100 / 200  in  FIGS.  18  to  20   ) in step M 220  may be performed by the devices shown in  FIGS.  18  to  20   . For example, referring to  FIG.  18   , the one or more processors  102  may control the one or more transceivers  106  and/or one or more memories  104  to transmit the HARQ-ACK feedback, and the one or more transceivers  106  may transmit the HARQ-ACK feedback to the BS. 
     The above-described operation and signaling performed by the BS/UE may be performed by the devices of  FIGS.  18  and  20   , which will be described later. For example, the BS may correspond to a first wireless device, and the UE may correspond to a second radio device. In addition, vice versa may be considered in some cases. 
     For example, the above-described operation and signaling performed by the BS/UE may be processed by one or more processors  102  and  202  of  FIGS.  18  to  20   , and the above-described operation and signaling performed by the BS/UE may be stored in a memory (e.g., one or more memories  104  and  204  of  FIG.  18   ) in the form of an instruction/program (e.g., executable code) for driving at least one processor (e.g., processors  102  and  202 ) of  FIGS.  18  to  20   . 
     It is obvious that each of the examples of the proposed methods may also be included as one implementation method, and thus each of the examples may be regarded as a kind of proposed method. Although the proposed methods may be implemented independently, some of the proposed methods may be combined (or merged) for implementation. In addition, it may be regulated that information on whether the proposed methods are applied (or information on rules related to the proposed methods) should be transmitted from the BS to the UE in a predefined signal (e.g., a physical layer signal, a higher layer signal, etc.). Higher layers may include, for example, at least one of the following functional layers: MAC, RLC, PDCP, RRC, and SDAP. 
     Methods, embodiments, or details for implementing the methods proposed in this specification (e.g., Proposal 1, Proposal 2, Proposal 3, Proposal 4, and Proposal 5) may be applied independently. Alternatively, at least one of the methods (embodiments or details) may be applied in combination. 
     Hereinafter, a description will be given in more detail with reference to the drawings. In the following drawings/description, the same reference symbols may denote the same or corresponding hardware blocks, software blocks, or functional blocks unless described otherwise. 
       FIG.  17    illustrates a communication system  1  applied to the present disclosure. 
     Referring to  FIG.  17   , a communication system  1  applied to the present disclosure includes wireless devices, Base Stations (BSs), and a network. Herein, the wireless devices represent devices performing communication using Radio Access Technology (RAT) (e.g., 5G New RAT (NR)) or Long-Term Evolution (LTE)) and may be referred to as communication/radio/5G devices. The wireless devices may include, without being limited to, a robot  100   a,  vehicles  100   b - 1  and  100   b - 2 , an eXtended Reality (XR) device  100   c,  a hand-held device  100   d,  a home appliance  100   e,  an Internet of Things (IoT) device  100   f,  and an Artificial Intelligence (AI) device/server  400 . For example, the vehicles may include a vehicle having a wireless communication function, an autonomous driving vehicle, and a vehicle capable of performing communication between vehicles. Herein, the vehicles may include an Unmanned Aerial Vehicle (UAV) (e.g., a drone). The XR device may include an Augmented Reality (AR)/Virtual Reality (VR)/Mixed Reality (MR) device and may be implemented in the form of a Head-Mounted Device (HMD), a Head-Up Display (HUD) mounted in a vehicle, a television, a smartphone, a computer, a wearable device, a home appliance device, a digital signage, a vehicle, a robot, etc. The hand-held device may include a smartphone, a smartpad, a wearable device (e.g., a smartwatch or a smartglasses), and a computer (e.g., a notebook). The home appliance may include a TV, a refrigerator, and a washing machine. The IoT device may include a sensor and a smartmeter. For example, the BSs and the network may be implemented as wireless devices and a specific wireless device  200   a  may operate as a BS/network node with respect to other wireless devices. 
     The wireless devices  100   a  to  100   f  may be connected to the network  300  via the BSs  200 . An AI technology may be applied to the wireless devices  100   a  to  100   f  and the wireless devices  100   a  to  100   f  may be connected to the AI server  400  via the network  300 . The network  300  may be configured using a 3G network, a 4G (e.g., LTE) network, or a 5G (e.g., NR) network. Although the wireless devices  100   a  to  100   f  may communicate with each other through the BSs  200 /network  300 , the wireless devices  100   a  to  100   f  may perform direct communication (e.g., sidelink communication) with each other without passing through the BS s/network. For example, the vehicles  100   b - 1  and  100   b - 2  may perform direct communication (e.g. Vehicle-to-Vehicle (V2V)/Vehicle-to-everything (V2X) communication). The IoT device (e.g., a sensor) may perform direct communication with other IoT devices (e.g., sensors) or other wireless devices  100   a  to  100   f.    
     Wireless communication/connections  150   a,    150   b,  or  150   c  may be established between the wireless devices  100   a  to  100   f /BS  200 , or BS  200 /BS  200 . Herein, the wireless communication/connections may be established through various RATs (e.g., 5G NR) such as uplink/downlink communication  150   a,  sidelink communication  150   b  (or, D2D communication), or inter BS communication (e.g. relay, Integrated Access Backhaul (IAB)). The wireless devices and the BSs/the wireless devices may transmit/receive radio signals to/from each other through the wireless communication/connections  150   a  and  150   b.  For example, the wireless communication/connections  150   a  and  150   b  may transmit/receive signals through various physical channels. To this end, at least a part of various configuration information configuring processes, various signal processing processes (e.g., channel encoding/decoding, modulation/demodulation, and resource mapping/demapping), and resource allocating processes, for transmitting/receiving radio signals, may be performed based on the various proposals of the present disclosure. 
       FIG.  18    illustrates wireless devices applicable to the present disclosure. 
     Referring to  FIG.  18   , a first wireless device  100  and a second wireless device  200  may transmit radio signals through a variety of RATs (e.g., LTE and NR). Herein, {the first wireless device  100  and the second wireless device  200 } may correspond to {the wireless device  100   x  and the BS  200 } and/or {the wireless device  100   x  and the wireless device  100   x } of  FIG.  17   . 
     The first wireless device  100  may include one or more processors  102  and one or more memories  104  and additionally further include one or more transceivers  106  and/or one or more antennas  108 . The processor(s)  102  may control the memory(s)  104  and/or the transceiver(s)  106  and may be configured to implement the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document. For example, the processor(s)  102  may process information within the memory(s)  104  to generate first information/signals and then transmit radio signals including the first information/signals through the transceiver(s)  106 . The processor(s)  102  may receive radio signals including second information/signals through the transceiver  106  and then store information obtained by processing the second information/signals in the memory(s)  104 . The memory(s)  104  may be connected to the processor(s)  102  and may store a variety of information related to operations of the processor(s)  102 . For example, the memory(s)  104  may store software code including commands for performing a part or the entirety of processes controlled by the processor(s)  102  or for performing the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document. Herein, the processor(s)  102  and the memory(s)  104  may be a part of a communication modem/circuit/chip designed to implement RAT (e.g., LTE or NR). The transceiver(s)  106  may be connected to the processor(s)  102  and transmit and/or receive radio signals through one or more antennas  108 . Each of the transceiver(s)  106  may include a transmitter and/or a receiver. The transceiver(s)  106  may be interchangeably used with Radio Frequency (RF) unit(s). In the present disclosure, the wireless device may represent a communication modem/circuit/chip. 
     The second wireless device  200  may include one or more processors  202  and one or more memories  204  and additionally further include one or more transceivers  206  and/or one or more antennas  208 . The processor(s)  202  may control the memory(s)  204  and/or the transceiver(s)  206  and may be configured to implement the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document. For example, the processor(s)  202  may process information within the memory(s)  204  to generate third information/signals and then transmit radio signals including the third information/signals through the transceiver(s)  206 . The processor(s)  202  may receive radio signals including fourth information/signals through the transceiver(s)  106  and then store information obtained by processing the fourth information/signals in the memory(s)  204 . The memory(s)  204  may be connected to the processor(s)  202  and may store a variety of information related to operations of the processor(s)  202 . For example, the memory(s)  204  may store software code including commands for performing a part or the entirety of processes controlled by the processor(s)  202  or for performing the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document. Herein, the processor(s)  202  and the memory(s)  204  may be a part of a communication modem/circuit/chip designed to implement RAT (e.g., LTE or NR). The transceiver(s)  206  may be connected to the processor(s)  202  and transmit and/or receive radio signals through one or more antennas  208 . Each of the transceiver(s)  206  may include a transmitter and/or a receiver. The transceiver(s)  206  may be interchangeably used with RF unit(s). In the present disclosure, the wireless device may represent a communication modem/circuit/chip. 
     Hereinafter, hardware elements of the wireless devices  100  and  200  will be described more specifically. One or more protocol layers may be implemented by, without being limited to, one or more processors  102  and  202 . For example, the one or more processors  102  and  202  may implement one or more layers (e.g., functional layers such as PHY, MAC, RLC, PDCP, RRC, and SDAP). The one or more processors  102  and  202  may generate one or more Protocol Data Units (PDUs) and/or one or more Service Data Unit (SDUs) according to the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document. The one or more processors  102  and  202  may generate messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document. The one or more processors  102  and  202  may generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document and provide the generated signals to the one or more transceivers  106  and  206 . The one or more processors  102  and  202  may receive the signals (e.g., baseband signals) from the one or more transceivers  106  and  206  and acquire the PDUs, SDUs, messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document. 
     The one or more processors  102  and  202  may be referred to as controllers, microcontrollers, microprocessors, or microcomputers. The one or more processors  102  and  202  may be implemented by hardware, firmware, software, or a combination thereof. As an example, one or more Application Specific Integrated Circuits (ASICs), one or more Digital Signal Processors (DSPs), one or more Digital Signal Processing Devices (DSPDs), one or more Programmable Logic Devices (PLDs), or one or more Field Programmable Gate Arrays (FPGAs) may be included in the one or more processors  102  and  202 . The descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document may be implemented using firmware or software and the firmware or software may be configured to include the modules, procedures, or functions. Firmware or software configured to perform the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document may be included in the one or more processors  102  and  202  or stored in the one or more memories  104  and  204  so as to be driven by the one or more processors  102  and  202 . The descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document may be implemented using firmware or software in the form of code, commands, and/or a set of commands. 
     The one or more memories  104  and  204  may be connected to the one or more processors  102  and  202  and store various types of data, signals, messages, information, programs, code, instructions, and/or commands. The one or more memories  104  and  204  may be configured by Read-Only Memories (ROMs), Random Access Memories (RAMs), Electrically Erasable Programmable Read-Only Memories (EPROMs), flash memories, hard drives, registers, cash memories, computer-readable storage media, and/or combinations thereof. The one or more memories  104  and  204  may be located at the interior and/or exterior of the one or more processors  102  and  202 . The one or more memories  104  and  204  may be connected to the one or more processors  102  and  202  through various technologies such as wired or wireless connection. 
     The one or more transceivers  106  and  206  may transmit user data, control information, and/or radio signals/channels, mentioned in the methods and/or operational flowcharts of this document, to one or more other devices. The one or more transceivers  106  and  206  may receive user data, control information, and/or radio signals/channels, mentioned in the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document, from one or more other devices. For example, the one or more transceivers  106  and  206  may be connected to the one or more processors  102  and  202  and transmit and receive radio signals. For example, the one or more processors  102  and  202  may perform control so that the one or more transceivers  106  and  206  may transmit user data, control information, or radio signals to one or more other devices. The one or more processors  102  and  202  may perform control so that the one or more transceivers  106  and  206  may receive user data, control information, or radio signals from one or more other devices. The one or more transceivers  106  and  206  may be connected to the one or more antennas  108  and  208  and the one or more transceivers  106  and  206  may be configured to transmit and receive user data, control information, and/or radio signals/channels, mentioned in the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document, through the one or more antennas  108  and  208 . In this document, the one or more antennas may be a plurality of physical antennas or a plurality of logical antennas (e.g., antenna ports). The one or more transceivers  106  and  206  may convert received radio signals/channels etc. from RF band signals into baseband signals in order to process received user data, control information, radio signals/channels, etc. using the one or more processors  102  and  202 . The one or more transceivers  106  and  206  may convert the user data, control information, radio signals/channels, etc. processed using the one or more processors  102  and  202  from the base band signals into the RF band signals. To this end, the one or more transceivers  106  and  206  may include (analog) oscillators and/or filters. 
     In the present disclosure, at least one memory (e.g.,  104  or  204 ) may store instructions or programs which, when executed, cause at least one processor operably coupled to the at least one memory to perform operations according to some embodiments or implementations of the present disclosure. 
     In the present disclosure, a computer-readable storage medium may store at least one instruction or computer program which, when executed by at least one processor, causes the at least one processor to perform operations according to some embodiments or implementations of the present disclosure. 
     In the present disclosure, a processing device or apparatus may include at least one processor and at least one computer memory coupled to the at least one processor. The at least one computer memory may store instructions or programs which, when executed, cause the at least one processor operably coupled to the at least one memory to perform operations according to some embodiments or implementations of the present disclosure. 
       FIG.  19    illustrates another example of a wireless device applied to the present disclosure. The wireless device may be implemented in various forms according to a use-case/service (refer to  FIG.  17   ). 
     Referring to  FIG.  19   , wireless devices  100  and  200  may correspond to the wireless devices  100  and  200  of  FIG.  18    and may be configured by various elements, components, units/portions, and/or modules. For example, each of the wireless devices  100  and  200  may include a communication unit  110 , a control unit  120 , a memory unit  130 , and additional components  140 . The communication unit may include a communication circuit  112  and transceiver(s)  114 . For example, the communication circuit  112  may include the one or more processors  102  and  202  and/or the one or more memories  104  and  204  of  FIG.  18   . For example, the transceiver(s)  114  may include the one or more transceivers  106  and  206  and/or the one or more antennas  108  and  208  of  FIG.  18   . The control unit  120  is electrically connected to the communication unit  110 , the memory  130 , and the additional components  140  and controls overall operation of the wireless devices. For example, the control unit  120  may control an electric/mechanical operation of the wireless device based on programs/code/commands/information stored in the memory unit  130 . The control unit  120  may transmit the information stored in the memory unit  130  to the exterior (e.g., other communication devices) via the communication unit  110  through a wireless/wired interface or store, in the memory unit  130 , information received through the wireless/wired interface from the exterior (e.g., other communication devices) via the communication unit  110 . 
     The additional components  140  may be variously configured according to types of wireless devices. For example, the additional components  140  may include at least one of a power unit/battery, input/output (I/O) unit, a driving unit, and a computing unit. The wireless device may be implemented in the form of, without being limited to, the robot ( 100   a  of  FIG.  17   ), the vehicles ( 100   b - 1  and  100   b - 2  of  FIG.  17   ), the XR device ( 100   c  of  FIG.  17   ), the handheld device ( 100   d  of  FIG.  17   ), the home appliance ( 100   e  of  FIG.  17   ), the IoT device ( 100   f  of  FIG.  17   ), a digital broadcast terminal, a hologram device, a public safety device, an MTC device, a medicine device, a fintech device (or a finance device), a security device, a climate/environment device, the AI server/device ( 400  of  FIG.  17   ), the BSs ( 200  of  FIG.  17   ), a network node, etc. The wireless device may be used in a mobile or fixed place according to a use-example/service. 
     In  FIG.  19   , the entirety of the various elements, components, units/portions, and/or modules in the wireless devices  100  and  200  may be connected to each other through a wired interface or at least a part thereof may be wirelessly connected through the communication unit  110 . For example, in each of the wireless devices  100  and  200 , the control unit  120  and the communication unit  110  may be connected by wire and the control unit  120  and first units (e.g.,  130  and  140 ) may be wirelessly connected through the communication unit  110 . Each element, component, unit/portion, and/or module within the wireless devices  100  and  200  may further include one or more elements. For example, the control unit  120  may be configured by a set of one or more processors. As an example, the control unit  120  may be configured by a set of a communication control processor, an application processor, an Electronic Control Unit (ECU), a graphical processing unit, and a memory control processor. As another example, the memory  130  may be configured by a Random Access Memory (RAM), a Dynamic RAM (DRAM), a Read Only Memory (ROM)), a flash memory, a volatile memory, a non-volatile memory, and/or a combination thereof 
     The wireless communication technology implemented in the wireless devices  100  and  200  of the present specification may include narrowband Internet of Things (NB-IoT) for low-power communication as well as LTE, NR, and 6G. For example, NB-IoT technology may be an example of low power wide area network (LPWAN) and implemented by standards such as LTE Cat NB1 and/or LTE Cat NB2, not limited to the above-mentioned names. Additionally or alternatively, the wireless communication technology implemented in the wireless devices  100  and  200  of the present disclosure may perform communication based on LTE-M. For example, LTE-M may be an example of LPWAN and called by various names such as enhanced machine type communication (eMTC). For example, LTE-M may be implemented by at least one of various standards such as 1) LTE CAT 0, 2) LTE Cat M1, 3) LTE Cat M2, 4) LTE non-bandwidth limited (non-BL), 5) LTE-MTC, 6) LTE machine type communication, and/or 7) LTE M, not limited to these names. Additionally or alternatively, the wireless communication technology implemented in the wireless devices  100  and  200  of the present disclosure may include at least one of ZigBee, Bluetooth, and low power wide area network (LPWAN) in consideration of low power communication, not limited to these names. For example, ZigBee may create a personal area network (PAN) related to small/low-power digital communication based on various standards such as IEEE 802.15.4, and may be called by various names. 
       FIG.  20    illustrates a vehicle or an autonomous driving vehicle applied to the present disclosure. The vehicle or autonomous driving vehicle may be implemented by a mobile robot, a car, a train, a manned/unmanned Aerial Vehicle (AV), a ship, etc. 
     Referring to  FIG.  20   , a vehicle or autonomous driving vehicle  100  may include an antenna unit  108 , a communication unit  110 , a control unit  120 , a driving unit  140   a,  a power supply unit  140   b,  a sensor unit  140   c,  and an autonomous driving unit  140   d.  The antenna unit  108  may be configured as a part of the communication unit  110 . The blocks  110 / 130 / 140   a  to  140   d  correspond to the blocks  110 / 130 / 140  of  FIG.  19   , respectively. 
     The communication unit  110  may transmit and receive signals (e.g., data and control signals) to and from external devices such as other vehicles, BSs (e.g., gNBs and road side units), and servers. The control unit  120  may perform various operations by controlling elements of the vehicle or the autonomous driving vehicle  100 . The control unit  120  may include an Electronic Control Unit (ECU). The driving unit  140   a  may cause the vehicle or the autonomous driving vehicle  100  to drive on a road. The driving unit  140   a  may include an engine, a motor, a powertrain, a wheel, a brake, a steering device, etc. The power supply unit  140   b  may supply power to the vehicle or the autonomous driving vehicle  100  and include a wired/wireless charging circuit, a battery, etc. The sensor unit  140   c  may acquire a vehicle state, ambient environment information, user information, etc. The sensor unit  140   c  may include an Inertial Measurement Unit (IMU) sensor, a collision sensor, a wheel sensor, a speed sensor, a slope sensor, a weight sensor, a heading sensor, a position module, a vehicle forward/backward sensor, a battery sensor, a fuel sensor, a tire sensor, a steering sensor, a temperature sensor, a humidity sensor, an ultrasonic sensor, an illumination sensor, a pedal position sensor, etc. The autonomous driving unit  140   d  may implement technology for maintaining a lane on which a vehicle is driving, technology for automatically adjusting speed, such as adaptive cruise control, technology for autonomously driving along a determined path, technology for driving by automatically setting a path if a destination is set, and the like. 
     For example, the communication unit  110  may receive map data, traffic information data, etc. from an external server. The autonomous driving unit  140   d  may generate an autonomous driving path and a driving plan from the obtained data. The control unit  120  may control the driving unit  140   a  such that the vehicle or the autonomous driving vehicle  100  may move along the autonomous driving path according to the driving plan (e.g., speed/direction control). In the middle of autonomous driving, the communication unit  110  may aperiodically/periodically acquire recent traffic information data from the external server and acquire surrounding traffic information data from neighboring vehicles. In the middle of autonomous driving, the sensor unit  140   c  may obtain a vehicle state and/or surrounding environment information. The autonomous driving unit  140   d  may update the autonomous driving path and the driving plan based on the newly obtained data/information. The communication unit  110  may transfer information about a vehicle position, the autonomous driving path, and/or the driving plan to the external server. The external server may predict traffic information data using AI technology, etc., based on the information collected from vehicles or autonomous driving vehicles and provide the predicted traffic information data to the vehicles or the autonomous driving vehicles. 
       FIG.  21    illustrates a very-small-aperture terminal (VSAT) to which the present disclosure is applied. 
     The VSAT  2120  may refer to an antenna/device capable of bidirectional communication with an antenna (plate) less than 3 meters. For example, the VSAT may be fixedly located on the ground or may be fixedly mounted on a vehicle, a marine vessel, and the like. For example, an NTN may be configured with the VSAT. Referring to  FIG.  21   , VSATs may be configured based on a mesh topology ( FIG.  21 ( a ) ) or a start topology ( FIG.  21 ( b ) ). For the mesh topology, each VSAT may be configured to directly communicate with other VSATs. For the start topology, multiple VSATs may be connected through a hub, and communication between VSATs may be performed through the hub. For example, the VSAT  2120  may serve as an NTN gateway/BS. For example, the VSAT  2120  may serve as an IAB node/BS on an IAB link, which will be described later. For example, an NTN gateway  420  may be connected to a satellite  2100 , the satellite  2100  may be connected to the VSAT  2120 , and the VSAT  2120  may be connected to a UE to provide services. In this case, the VSAT  2120  may communicate with the satellite  430  as an IAB mobile termination (IAB-MT) and provide services to the UE as an IAB distributed unit (DU). In addition, the satellite  2100  may operate as a parent node. 
       FIG.  22    illustrates an exemplary IAB to which the present disclosure is applied. 
     An IAB node (relay node) may multiplex access and backhaul links in the time, frequency and/or space (e.g., beam-based operation) domain. The IAB node means a RAN node that supports a radio access link for UEs and/or a radio backhaul link for parent and child nodes. From the perspective of the network, an IAB donor may be a terminating node of NR backhauling. That is, the IAB donor may provide the UE with an interface for accessing a core network. In addition, the IAB donor may be a RAN node that provides a wireless backhaul link to the IAB node. The parent node may be a next-hop neighbor node of an IAB node MT, and the parent node may be an IAB node or an IAB donor DU. The child node may be a next-hop neighbor node of an IAB node DU, and the child node may also correspond to an IAB node. 
     In IAB links, upstream refers to the direction of a parent node in the IAB topology, and downstream refers to the direction of a child node or UE of in the IAB topology. An access link refers to a link between an access UE and an IAB node or IAB donor, and a backhaul link refers to a link between an IAB node and an IAB child node or an IAB parent node. The access and backhaul links may operate at the same or different frequencies. The IAB may reuse functions and interfaces defined for conventional access (for in-band and out-of-band relays). For example, a NR Uu interface may be used for the access link, and the above-described F1 interface may be extended and applied to the backhaul link. For example, when the F1 interface is applied to the backhaul link, a gNB DU may be interpreted as an IAB node, and a gNB central unit (CU) may be interpreted as an IAB donor. 
     For example, in  FIG.  6   , a connection between the UE (BS)  430 , the satellite  410 , and the gateway  420  may be interpreted as an IAB link of  FIG.  22   . In the NTN, the satellite  410  may operate as an IAB node, and the NTN gateway  420  may operate as a parent node, an IAB donor, and/or a child node. Alternatively, the BS may operate as an IAB node, and the satellite  410  may operate as a parent node and/or a child node. Further, the satellite  410  may operate as an IAB node, and the BS may operate as a parent node and/or a child node. 
     For firmware or software implementation, an embodiment of the present disclosure may be implemented in the form of a module, a procedure, a function, and so on for performing the above-described functions or operations. Software code may be stored in a memory and executed by a processor. The memory is located at the interior or exterior of the processor and may transmit and receive data to and from the processor via various known means. 
     The above-described embodiments are combinations of elements and features of the present disclosure in specific forms. The elements or features may be considered selective unless mentioned otherwise. Each element or feature may be implemented without being combined with other elements or features. Further, the embodiments of the present disclosure may be configured by combining some of the elements and/or features. The order of operations described in the embodiments of the present disclosure may be rearranged. Several configurations or features of any one embodiment may be included in another embodiment or may be replaced with related configurations or features of another embodiment. It is obvious that claims that are not explicitly cited in the appended claims may be combined to form an embodiment or included as a new claim by amendment after filing. 
     Various embodiments of the present disclosure may be carried out in other specific ways than those set forth herein without departing from the essential characteristics of the present disclosure. The above implementations are therefore to be construed in all aspects as illustrative and not restrictive. The scope of the disclosure should be determined by the appended claims and their legal equivalents, not by the above description, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein. 
     INDUSTRIAL APPLICABILITY 
     The present disclosure may be used for a user equipment (UE), a base station (BS), or other devices in wireless mobile communication systems.