Terminal device, base station device, method for controlling terminal device and method for controlling base station device

Abstract

To provide a terminal device, a base station device, a control method for a terminal device, and a control method for a base station device that contribute to achievement of a desired communication quality.SOLUTION: In a wireless communication system, a terminal device includes a wireless communication unit and a control unit. The control unit receives invalid information of HARQ (Hybrid Automatic Repeat reQuest) feedback via the wireless communication unit, and recognizes that one or more HARQ feedbacks indicated by the invalid information of HARQ feedback are invalid. The invalid information of HARQ feedback is set for each cell, each beam, each component carrier, each BWP (BandWidth Part), each UE (User Equipment), or each HARQ process.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] An embodiment of the present invention relates to a terminal device, a base station device, a control method for a terminal device, and a control method for a base station device. [Background technology]

[0002] 3GPP (registered trademark) 3rd Generation Partnership Project) Rel.15 NR (New Radio) supports HARQ (Hybrid Automatic Repeat reQuest) in the same way as LTE (Long Term Evolution). In HARQ, error correction is performed by combining (soft combining) the initially transmitted data and the retransmitted data. This makes it possible to obtain coding gain. This process is performed for each process called a "HARQ process." In other words, when there are multiple (e.g. 16) HARQ processes, it is possible to perform HARQ processes in parallel.

[0003] Since various use cases are assumed in NR, depending on the use case, the number of HARQ processes may be insufficient. For example, in the case of low-latency processing and communication (e.g., URLLC (Ultra-Reliable and Low Latency Communications)), data may be received one after another in a short time, and the number of HARQ processes may be insufficient because HARQ processing cannot keep up. In addition, in the case of NTN (Non-Terrestrial Network) communication, delays in HARQ process processing due to propagation delays may occur, and the number of HARQ processes may be insufficient. Regarding this insufficient number of HARQ processes, it is known that HARQ FEEDBACK can be deactivated or disabled. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] PR-190710 Revised SID for Study on solutions for NR to support non-terrestrial networks (NTN) [Non-Patent Document 2] R1-1906088, Nokia, Nokia Shanghai Bell, “Consideration on HARQ in NTN,” 3GPP TSG RAN1 Meeting#97, Reno, USA, May, 2019 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the above conventional technology, a specific method of HARQ FEEDBACK disabling has not been fully considered. A detailed setting method of HARQ FEEDBACK disabling for a terminal device is not clear. For this reason, the shortage of the number of HARQ processes is not resolved, and there is a possibility that a desired communication quality cannot be obtained.

[0006] Therefore, an object of the present disclosure is to provide a terminal device, a base station device, a control method for a terminal device, and a control method for a base station device that contribute to obtaining a desired communication quality. [Means for solving the problem]

[0007] In order to solve the above problem, a terminal device according to an embodiment of the present disclosure includes a communication unit and a control unit. The control unit is configured to receive disabling information of a Hybrid Automatic Repeat reQuest (HARQ) feedback via the communication unit and recognize that one or more HARQ feedbacks indicated by the disabling information of the HARQ are disabled, and the disabling information of the HARQ is set for each cell, each beam, each component carrier, each BandWidth Part (BWP), each User Equipment (UE), or each HARQ process. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating a configuration example of a communication system according to an embodiment of the present disclosure. [Diagram 2] FIG. 1 is a diagram illustrating an example of a wireless network provided by a communication system. [Diagram 3] FIG. 1 is a diagram showing an overview of satellite communication provided by a communication system. [Figure 4] FIG. 2 is a diagram showing an example of a cell formed by a satellite station; [Diagram 5] FIG. 2 is a diagram illustrating a configuration example of a management device according to an embodiment of the present disclosure. [Figure 6] FIG. 2 is a diagram illustrating a configuration example of a non-terrestrial station according to an embodiment of the present disclosure. [Figure 7] FIG. 2 is a diagram illustrating a configuration example of a terminal device according to an embodiment of the present disclosure. [Figure 8] 13 is a flowchart illustrating an example of an initial connection process. [Figure 9] FIG. 11 is a sequence diagram showing an example of a HARQ procedure. [Figure 10] FIG. 1 is an explanatory diagram illustrating an overview of an HARQ buffer. [Figure 11] FIG. 11 is a sequence diagram illustrating an example of a HARQ disabling process according to an embodiment of the present disclosure. [Figure 12] FIG. 11 is a sequence diagram illustrating an example of a HARQ disabling process according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the following embodiments, the same components are designated by the same reference numerals, and duplicated descriptions will be omitted.

[0010] In addition, in this specification and drawings, multiple components having substantially the same functional configuration may be distinguished by adding different numbers after the same reference numeral. For example, multiple components having substantially the same functional configuration may be distinguished as necessary, such as terminal devices 501, 502, and 503. However, when there is no need to particularly distinguish between multiple components having substantially the same functional configuration, only the same reference numerals are attached. For example, when there is no need to particularly distinguish between terminal devices 501, 502, and 503, they are simply referred to as terminal device 50.

[0011] The present disclosure will be described in the following order. 1. Introduction 2. Embodiment 2-1. Overall configuration of the communication system 2-2. Management device configuration 2-3. Base station configuration 2-4. Relay station configuration 2-5. Terminal device configuration 2-6. Initial connection process 2-7.An example of HARQ procedure 2-8.Propagation delay problem 2-9. Overview of the embodiment 2-10. Example of HARQ disabling process (downlink) 2-11. Example of HARQ disabling process (uplink) 2-12.Characteristic compensation for HARQ disabling 3. Variations 3-1. Modification when the number of HARQ processes can be increased 3-2.Other modifications 4. Conclusion

[0012] <1. Introduction> Radio access technologies such as LTE and NR are being considered by 3GPP. LTE and NR are types of cellular communication technologies that enable mobile communication for terminal devices by arranging multiple areas covered by base stations in the form of cells. In the following explanation, "LTE" includes LTE-A (LTE-Advanced), LTE-A Pro (LTE-Advanced Pro), and EUTRA (Evolved Universal Terrestrial Radio Access). In addition, NR includes NRAT (New Radio Access Technology) and FEUTRA (Further EUTRA).

[0013] NR is the next generation (5th generation) radio access technology (RAT) after LTE. NR is a radio access technology that can support various use cases including eMBB (Enhanced Mobile Broadband), mMTC (Massive Machine Type Communications) and URLLC. NR is being studied with the aim of creating a technology framework that can support the usage scenarios, requirements, and deployment scenarios of these use cases.

[0014] For example, due to the increasing demand for wide-area coverage and connection stability, non-terrestrial networks (NTNs) have been considered as one of the use cases for NR. In non-terrestrial networks, it is planned that wireless networks will be provided to terminal devices via base stations other than terrestrial stations, such as satellite stations and aircraft stations. These base stations other than terrestrial stations are called non-terrestrial stations or non-terrestrial base stations. The wireless network provided by terrestrial stations is called a terrestrial network (TN). By using the same wireless access method for the terrestrial network and the non-terrestrial network, integrated operation of the terrestrial network and the non-terrestrial network will be possible.

[0015] In the embodiments of the present disclosure, a terrestrial station (also referred to as a terrestrial base station) refers to a base station (including a relay station) installed on the ground. "Terrestrial" is defined in a broad sense to include not only ground (on land) but also underground, on water, and underwater.

[0016] In addition, in some embodiments, application examples to NTNs will be described as one of the use cases of NR. However, the application of these embodiments is not limited to NTNs, and may be applied to other technologies and use cases (e.g., URLLC).

[0017] <2. Embodiment> A communication system 1 according to this embodiment will be described below. The communication system 1 includes a non-terrestrial station and provides wireless communication using a non-terrestrial network to a terminal device. The communication system 1 may also provide wireless communication using a terrestrial network. Note that the non-terrestrial network and the terrestrial network included in the communication system 1 are not limited to wireless networks using a wireless access method defined by NR. The non-terrestrial network included in the communication system 1 may be a wireless network using a wireless access method other than NR, such as LTE, W-CDMA (Wideband Code Division Multiple Access), or cdma2000 (Code Division Multiple Access 2000).

[0018] In the following description, the concept of a base station (hereinafter also referred to as a base station device) may include a relay station (hereinafter also referred to as a relay device (relay node)) and a donor base station that provides a radio interface to the relay station. The concept of a base station includes not only a structure having the functions of a base station, but also a device installed in the structure. The structure is, for example, a high-rise building, a house, a steel tower, a station facility, an airport facility, a port facility, a stadium, and other buildings. The concept of a structure includes not only a building, but also a non-building structure such as a tunnel, a bridge, a dam, a fence, and an iron pillar, and equipment such as a crane, a gate, and a windmill. The concept of a structure includes not only a ground (land) or underground structure, but also a structure on water such as a pier or a megafloat, and an underwater structure such as an ocean observation facility. Furthermore, a base station may be composed of a set of multiple physical or logical devices. For example, in the embodiment of the present disclosure, the base station may be divided into a plurality of devices, a BBU (Baseband Unit) and a RU (Radio Unit), and may be interpreted as a collection of these devices. Additionally or alternatively, in the embodiment of the present disclosure, the base station may be either or both of a BBU and a RU. The BBU and the RU may be connected by a predetermined interface (e.g., eCPRI). Additionally or alternatively, the RU may be referred to as a Remote Radio Unit (RRU) or a Radio DoT (RD). Additionally or alternatively, the RU may be compatible with gNB-DU, which will be described later. Additionally or alternatively, the BBU may be compatible with gNB-CU, which will be described later. Additionally or alternatively, the RU may be a device formed integrally with an antenna. The antenna of the base station (e.g., an antenna formed integrally with the RU) may adopt an Advanced Antenna System and support MIMO (e.g., FD-MIMO) and beamforming. In the Advanced Antenna System, an antenna in a base station (eg, an antenna formed integrally with an RU) may have, for example, 64 transmitting antenna ports and 64 receiving antenna ports.

[0019] The base station may be a mobile base station. For example, the base station may be a device installed in a mobile body, or may be the mobile body itself. The mobile body may be a mobile terminal such as a smartphone, a mobile body moving on the ground (land) (for example, a vehicle such as a car, a bus, a truck, a train, or a linear motor car), or a mobile body moving underground (for example, in a tunnel) (for example, a subway). The mobile body may be a mobile body moving on the water (for example, a ship such as a passenger ship, a cargo ship, or a hovercraft), or a mobile body moving underwater (for example, a submarine such as a submarine, a submarine, or an unmanned submersible). The mobile body may be a mobile body moving within the atmosphere (for example, an aircraft such as an airplane, an airship, or a drone), or a space mobile body moving outside the atmosphere (for example, an artificial celestial body such as an artificial satellite, a spaceship, a space station, or a probe).

[0020] In addition, multiple base stations may be connected to each other. One or more base stations may be included in a Radio Access Network (RAN). That is, a base station may simply be referred to as a RAN, a RAN node, an AN (Access Network), or an AN node. The RAN in LTE is called EUTRAN (Enhanced Universal Terrestrial RAN). The RAN in NR is called NGRAN. The RAN in W-CDMA (UMTS) is called UTRAN. An LTE base station is called eNodeB (Evolved Node B) or eNB. That is, the EUTRAN includes one or more eNodeBs (eNBs). Also, an NR base station is called gNodeB or gNB. That is, the NGRAN includes one or more gNBs. Furthermore, the EUTRAN may include a gNB (en-gNB) connected to a core network (EPC) in an LTE communication system (EPS). Similarly, the NGRAN may include an ng-eNB connected to a core network 5GC in a 5G communication system (5GS). Additionally or alternatively, when the base station is an eNB, gNB, etc., it may be referred to as 3GPP Access. Additionally or alternatively, when the base station is a wireless access point (Access Point), it may be referred to as Non-3GPP Access. Additionally or alternatively, the base station may be a radio extension device called an RRH (Remote Radio Head). Additionally or alternatively, when the base station is a gNB, it may be referred to as a combination of the above-mentioned gNB CU (Central Unit) and gNB DU (Distributed Unit), or any one of them. The gNB CU (Central Unit) hosts multiple upper layers (e.g. RRC, SDAP, PDCP) of the Access Stratum for communication with the UE. On the other hand, the gNB-DU hosts multiple lower layers (e.g. RLC, MAC, PHY) of the Access Stratum.That is, among the messages and information described later, RRC signaling (semi-static notification) may be generated by the gNB CU, while DCI (dynamic notification) may be generated by the gNB-DU. Alternatively, among the RRC configurations (semi-static notification), some configurations such as IE:cellGroupConfig may be generated by the gNB-DU, and the remaining configurations may be generated by the gNB-CU. These configurations may be transmitted and received via the F1 interface described later. A base station may be configured to be able to communicate with other base stations. For example, when multiple base station devices are eNBs or a combination of eNBs and en-gNBs, the base stations may be connected via an X2 interface. Additionally or alternatively, when multiple base stations are gNBs or a combination of gn-eNBs and gNBs, the devices may be connected via an Xn interface. Additionally or alternatively, when multiple base stations are a combination of gNB CU (Central Unit) and gNB DU (Distributed Unit), the devices may be connected via the F1 interface described above. Message information (RRC signaling or DCI information) described below may be communicated between multiple base stations (e.g., via X2, Xn, and F1 interfaces).

[0021] In LTE and NR, a terminal device (also referred to as a mobile station, mobile station device, or terminal) may be referred to as UE (User Equipment). Alternatively, the terminal device may be referred to as MS (Mobile Station) or WTRU (Wireless Transmission Reception Unit). Note that the terminal device is a type of wireless communication device, and is also referred to as a mobile station, mobile station device, or terminal. In the embodiment of the present disclosure, the concept of a terminal device includes not only a portable terminal device such as a mobile terminal, but also a device installed in a structure or a moving object, for example.

[0022] <2-1. Overall configuration of the communication system> Fig. 1 is a diagram showing a configuration example of a communication system 1 according to an embodiment of the present disclosure. The communication system 1 includes a management device 10, a non-terrestrial base station (hereinafter simply referred to as a base station) 20, a terrestrial base station (hereinafter simply referred to as a base station) 30, a relay device (hereinafter simply referred to as a base station) 40, and a terminal device 50. The communication system 1 provides a wireless network that enables mobile communication to a user by the wireless communication devices constituting the communication system 1 operating in cooperation with each other. The wireless communication device is a device having a wireless communication function, and in the example of Fig. 1, the base stations 20, 30, 40 and the terminal device 50 correspond to the wireless communication devices.

[0023] The communication system 1 may include a plurality of management devices 10, base stations 20, 30, 40, and terminal devices 50. In the example of FIG. 1, the communication system 1 includes management devices 101, 102, etc. as the management device 10. The communication system 1 also includes base stations 201, 202, etc. as the base station 20, and includes base stations 301, 302, etc. as the base station 30. The communication system 1 also includes base stations 401, 402, etc. as the base station 40, and includes terminal devices 501, 502, 503, etc. as the terminal device 50. As described above, the application of the embodiment of the present disclosure is not limited to non-terrestrial communication (NTN). That is, the communication system does not need to include a non-terrestrial station.

[0024] The management device 10 is a device that manages a wireless network. For example, the management device 10 is a device that functions as an MME (Mobility Management Entity) or an AMF (Access and Mobility Management Function). The MME is connected to the EUTRAN via an S1 interface, and controls NAS (Non-Access Stratum) signaling between the UE and the AMF, and manages the mobility of the UE. The AMF is connected to the NGRAN via an NG interface, and controls NAS (Non-Access Stratum) signaling between the UE and the AMF, and manages the mobility of the UE. The management device 10 may be included in a core network CN. The core network CN is, for example, an EPC (Evolved Packet Core) or a 5GC (5G Core network). The management device 10 is connected to each of a plurality of base stations 20 and a plurality of base stations 30. The management device 10 manages the communication between the base stations 20 and the base stations 30. The core network transfers user data between a packet data network (PDN) or a data network (DN) and a RAN in addition to a control plane (C-Plane) node such as the management device 10. It may also include a user plane (U-Plane) node. The U-Plane node in the EPC may include a Serving Gateway (S-GW) or a PDN-Gateway (P-GW). The U-Plane node in the 5GC may include a U-Plane Function (UPF). For example, the management device 10 manages the location of the terminal device 50 (UE) in the communication system 1 for each terminal device 50 in an area unit (e.g. Tracking Area, RAN Notification Area) consisting of multiple cells. The management device 10 may grasp and manage for each terminal device 50, which base station (or which cell) the terminal device 50 is connected to, which base station (or which cell) the terminal device 50 is present in the communication area of, etc., for each cell unit.

[0025] The base station 20 is a base station that wirelessly communicates with the terminal device 50. In the example of Fig. 1, the base station 201 is connected to the base station 401, and can wirelessly communicate with the terminal device 50 via the base station 401. In this embodiment, the base station 20 is a base station that can float in the air or space. For example, the base station 20 is a non-terrestrial station device such as an aircraft station or a satellite station.

[0026] The aircraft station is, for example, a wireless communication device capable of floating in the atmosphere, such as an aircraft. The aircraft station may be, for example, a device mounted on an aircraft, or may be the aircraft itself. The concept of an aircraft includes not only heavier aircraft such as airplanes and gliders, but also lighter aircraft such as balloons and airships. The concept of an aircraft includes not only heavier aircraft and lighter aircraft, but also rotorcraft such as helicopters and autogyros. The aircraft station (or an aircraft on which the aircraft station is mounted) may be an unmanned aircraft such as a drone (Aerial Vehicle). The concept of an unmanned aircraft also includes unmanned aerial systems (UAS: Unmanned Aircraft Systems) and tethered unmanned aerial systems (tethered UAS). The concept of an unmanned aircraft also includes lighter unmanned aerial systems (LTA: Lighter than Air UAS) and heavy unmanned aerial systems (HTA: Heavier than Air UAS). The concept of an unmanned aircraft also includes high altitude unmanned aerial system platforms (HAPs: High Altitude UAS Platforms). Furthermore, when an aircraft station functions as a UE, the aircraft station may be an Aerial UE.

[0027] A satellite station is a wireless communication device capable of floating outside the atmosphere. A satellite station may be a device mounted on a space vehicle such as an artificial satellite, or may be the space vehicle itself. A satellite serving as a satellite station may be any of a low earth orbit (LEO) satellite, a medium earth orbit (MEO) satellite, a geostationary earth orbit (GEO) satellite, and a highly elliptical orbit (HEO) satellite. Of course, a satellite station may be a device mounted on a low earth orbit satellite, a medium earth orbit satellite, a geostationary satellite, or a highly elliptical orbit satellite.

[0028] The base station 30 is a base station that wirelessly communicates with the terminal device 50. In the example of FIG. 1, the base station 301 is connected to the base station 402, and can wirelessly communicate with the terminal device 50 via the base station 402. The base station 30 may be a base station disposed in a structure on the ground, or a base station installed in a mobile object moving on the ground. For example, the base station 30 is an antenna installed in a structure such as a building and a signal processing device connected to the antenna. Of course, the base station 30 may be the structure or the mobile object itself.

[0029] The base station 40 is a device that serves as a relay station for the base stations. The base station 40 is a type of base station. The base station 40 relays communication between the base station 20 and the terminal device 50, or communication between the base station 30 and the terminal device 50. The base station 40 may be a terrestrial station or a non-terrestrial station. The base station 40 may configure a radio access network RAN ​​together with the base station 20 and the base station 30.

[0030] The terminal device 50 is, for example, a mobile phone, a smart device (smartphone or tablet), a PDA (Personal Digital Assistant), or a personal computer. The terminal device 50 may be an M2M (Machine to Machine) device or an IoT (Internet of Things) device (for example, it may be called an MTC UE, an NB-IoT UE, or a Cat.M UE). The terminal device 50 may be a wireless communication device installed in a mobile object, or may be the mobile object itself. The terminal device 50 may be a relay station that relays satellite communication, or a base station that receives satellite communication. The terminal device 50 supports both terrestrial networks and non-terrestrial networks. Therefore, the terminal device 50 can communicate not only with terrestrial station devices such as the base station 30, but also with non-terrestrial station devices such as the base station 20.

[0031] FIG. 2 is a diagram showing an example of a wireless network provided by a communication system 1. Each of the base stations 20 and 30 constitutes a cell. A cell is an area covered by wireless communication by a base station. The cell constituted by the base station 20 and the base station 30 may be any of a macrocell, a microcell, a femtocell, and a small cell. The communication system 1 may be configured such that a single base station manages multiple cells, or such that multiple base stations manage one cell. A cell provided by a base station is called a serving cell. The serving cell includes a PCell (Primary Cell) and a SCell (Secondary Cell). When dual connectivity (e.g. EUTRA-EUTRA Dual Connectivity, EUTRA-NR Dual Connectivity (ENDC), EUTRA-NR Dual Connectivity with 5GC, NR-EUTRA Dual Connectivity (NEDC), NR-NR Dual Connectivity) is provided to a UE (e.g. terminal device 50), a PCell and zero or more SCell(s) provided by a MN (Master Node) are called a Master Cell Group. Furthermore, the serving cell may include a PSCell (Primary Secondary Cell or Primary SCG Cell). That is, when Dual Connectivity is provided to a UE, the PSCell and zero or more SCell(s) provided by an SN (Secondary Node) are called a Secondary Cell Group (SCG). Unless special configuration (e.g., PUCCH on SCell) is performed, the Physical Uplink Control Channel (PUCCH) is transmitted on the PCell and PSCell, but not on the SCell. In addition, Radio Link Failure is detected on the PCell and PSCell, but is not detected (does not need to be detected) on the SCell.As described above, the PCell and the PSCell have a special role among the Serving Cell(s), and are therefore also called Special Cells (SpCells). One Downlink Component Carrier and one Uplink Component Carrier may be associated with one cell. Furthermore, the system bandwidth corresponding to one cell may be divided into a plurality of bandwidth parts. In this case, one or a plurality of Bandwidth Parts may be configured for a UE, and one Bandwidth Part may be used by the UE as an Active BWP. Furthermore, the radio resources (e.g., frequency band, numerology (subcarrier spacing), slot format (Slot configuration)) that the terminal device 50 can use may differ for each cell, each component carrier, or each BWP.

[0032] In the example of Fig. 2, base stations 301 and 302 constitute a terrestrial network TN1, and base stations 303, 304, and 305 constitute a terrestrial network TN2. The terrestrial networks TN1 and TN2 are terrestrial networks operated by a wireless communication carrier (Mobile Network Operator: MNO) such as a telephone company, for example. The terrestrial networks TN1 and TN2 may be operated by different wireless communication carriers (i.e., MNOs with different PLMNs) or may be operated by the same wireless communication carrier. The terrestrial networks TN1 and TN2 can also be regarded as one terrestrial network.

[0033] The terrestrial network TN1 and the terrestrial network TN2 are each connected to a core network. In the example of FIG. 2, the base station 30 constituting the terrestrial network TN2 is connected to a core network CN constituted by the management device 101 and the like. If the radio access method of the terrestrial network TN2 is LTE, the core network CN is EPC. Also, if the radio access method of the terrestrial network TN2 is NR, the core network CN is 5GC. Of course, the core network CN is not limited to EPC or 5GC, and may be a core network of another radio access method. Note that, in the example of FIG. 2, the terrestrial network TN1 is not connected to a core network, but the terrestrial network TN1 may be connected to the core network CN. Also, the terrestrial network TN1 may be connected to a core network (not shown) different from the core network CN.

[0034] The core network CN includes a gateway device, a gateway exchange, etc., and is connected to the public network PN via the gateway device. The public network PN is, for example, a public data network such as the Internet, a regional IP network, or a telephone network (a mobile phone network, a landline telephone network, etc.). The gateway device is, for example, a server device connected to the Internet, a regional IP network, etc. The gateway exchange is, for example, an exchange connected to a telephone network of a telephone company. The management device 101 may have a function as a gateway device or a gateway exchange.

[0035] Both the base station 20 and the base station 40 shown in FIG. 2 are non-terrestrial station devices such as satellite stations and aircraft stations. A group of satellite stations (or a single satellite station) constituting a non-terrestrial network is called a spaceborne platform. Also, a group of aircraft stations (or a single aircraft station) constituting a non-terrestrial network is called an airborne platform. In the example of FIG. 2, the base station 202, the base station 401, and the base station 402 constitute a spaceborne platform SBP1, and the base station 201 constitutes a spaceborne platform SBP2. Also, the base station 203 constitutes an airborne platform ABP1.

[0036] The terminal device 50 can communicate with both the base station 30 and the base station 20. In the example of FIG. 2, the terminal device 501 can communicate with the base station 30 constituting the terrestrial network TN1. The terminal device 501 can also communicate with the base station 20 constituting the spaceborne platforms SBP1 and SBP2. The terminal device 501 can also communicate with the base station 20 constituting the airborne platform ABP1. The terminal device 501 may also be able to directly communicate with another terminal device 50 (terminal device 502 in the example of FIG. 2).

[0037] The base stations 20 connect to a terrestrial network or a core network via a relay station 60. The base stations 20 constituting the spaceborne platforms SBP1 and SBP2 connect to the terrestrial network TN1 via a relay station 601. The base stations 20 constituting the spaceborne platforms SBP1 and SBP2 and the airborne platform ABP1 connect to the core network CN via a relay station 602. The base stations 20 can also directly communicate with each other without going through the relay station 60.

[0038] The relay station 60 is, for example, an aviation station or an earth station. An aviation station is a radio station installed on the ground or on a mobile object moving on the ground in order to communicate with an aircraft station. An earth station is a radio station located on the earth (including in the air) in order to communicate with a satellite station (space station). An earth station may be a large earth station or a small earth station such as a VSAT (Very Small Aperture Terminal). An earth station may be a VSAT control earth station (also called a master station or a HUB station) or a VSAT earth station (also called a slave station). An earth station may be a radio station installed on a mobile object moving on the ground. For example, an on-board earth station (ESV: Earth Stations on board Vessels) is an example of an earth station mounted on a ship. An earth station may include an aircraft earth station installed on an aircraft (including a helicopter) and communicating with a satellite station. An earth station may include an aircraft earth station installed on a mobile object moving on the ground and communicating with an aircraft earth station via a satellite station. The relay station 60 may be a portable, mobile radio station that communicates with a satellite station or an aircraft station. The relay station 60 may be considered as a part of the communication system 1.

[0039] Each device constituting the spaceborne platforms SBP1 and SBP2 performs satellite communication with the terminal device 50. Satellite communication refers to wireless communication between a satellite station and the terminal device 50. Fig. 3 is a diagram showing an overview of satellite communication provided by the communication system 1. Satellite stations are mainly divided into geostationary satellite stations and low-earth orbit satellite stations.

[0040] A geostationary satellite station is located at an altitude of approximately 35,786 km, and revolves around the Earth at the same speed as the Earth's rotation speed. In the example of Fig. 3, the base station 201 constituting the spaceborne platform SBP2 is a geostationary satellite station. The relative speed of a geostationary satellite station with respect to a terrestrial terminal device 50 is nearly zero, and the geostationary satellite station is observed by the terrestrial terminal device 50 as if it were stationary. The base station 201 performs satellite communication with terminal devices 501, 503, 504, etc. located on the Earth.

[0041] A low-earth orbit satellite station is a satellite station that orbits at a lower altitude than a geostationary satellite station or a medium-earth orbit satellite station. A low-earth orbit satellite station is, for example, a satellite station located between 500 km and 2000 km in altitude. In the example of FIG. 3, the base stations 202 and 203 constituting the spaceborne platform SBP1 are low-earth orbit satellite stations. Note that FIG. 3 shows only two satellite stations, the base station 202 and the base station 203, constituting the spaceborne platform SBP1. However, in reality, the satellite stations constituting the spaceborne platform SBP1 form a low-earth orbit satellite constellation by two or more (for example, tens to thousands) base stations 20. Unlike a geostationary satellite station, a low-earth orbit satellite station has a relative speed with a terminal device 50 on the ground, and is observed as if it is moving from the terminal device 50 on the ground. The base stations 202 and 203 each form a cell and perform satellite communication with terminal devices 501, 502, 503, etc. located on the earth.

[0042] FIG. 4 is a diagram showing an example of a cell formed by a satellite station. FIG. 4 shows a cell C2 formed by a base station 203, which is a low-earth orbit satellite station. The satellite station orbiting in a low-earth orbit has a predetermined directivity on the ground and communicates with a terminal device 50 on the ground. For example, the angle R1 shown in FIG. 4 is 40°. In the case of FIG. 4, the radius D1 of the cell C2 formed by the base station 203 is, for example, 1000 km. The low-earth orbit satellite station moves at a constant speed. If it becomes difficult for the low-earth orbit satellite station to provide satellite communication to the terminal device 50 on the ground, the subsequent low-earth orbit satellite station provides satellite communication. In the example of FIG. 4, if it becomes difficult for the base station 203 to provide satellite communication to the terminal device 50 on the ground, the subsequent base station 204 provides satellite communication. Note that the values ​​of the angle R1 and the radius D1 described above are merely examples and are not limited to the above.

[0043] As described above, the terminal device 50 can perform wireless communication using a non-terrestrial network. The base station 20 and the base station 40 of the communication system 1 constitute a non-terrestrial network. This enables the communication system 1 to extend services to the terminal device 50 located in an area that cannot be covered by the terrestrial network. For example, the communication system 1 can provide public safety communication and critical communication to the terminal device 50 such as an IoT (Internet of Things) device or an MTC (Machine Type Communications) device. Furthermore, the use of a non-terrestrial network improves service reliability and recovery, so that the communication system 1 can reduce the vulnerability of the service to physical attacks or natural disasters. Furthermore, the communication system 1 can realize service connection to aircraft terminal devices such as airplane passengers and drones, and service connection to mobile terminal devices such as ships and trains. In addition, the communication system 1 can realize the provision of A / V content, group communication, IoT broadcast service, software download service, highly efficient multicast services such as emergency messages, highly efficient broadcast services, and the like. Furthermore, the communication system 1 can realize traffic offload between the terrestrial network and the non-terrestrial network. To achieve these, it is desirable, but not limited to, that the non-terrestrial network provided by the communication system 1 be operationally integrated at a higher layer with the terrestrial network provided by the communication system 1. Also, it is desirable, but not limited to, that the non-terrestrial network provided by the communication system 1 share a radio access method with the terrestrial network provided by the communication system 1.

[0044] Next, the configuration of each device constituting the communication system 1 according to this embodiment will be specifically described.

[0045] <2-2. Management device configuration> The management device 10 is a device that manages a wireless network. For example, the management device 10 is a device that manages communication between the base station 20 and the base station 30. If the core network is the EPC, the management device 10 is a device that has a function as, for example, an MME (Mobility Management Entity). If the core network is the 5GC, the management device 10 is a device that has a function as, for example, an AMF (Access and Mobility Management Function). The management device 10 may have a gateway function. For example, if the core network is the EPC, the management device 10 may have a function as an S-GW (Serving Gateway) or a P-GW (Packet Data Network Gateway). If the core network is the 5GC, the management device 10 may have a function as a UPF (User Plane Function). The management device 10 does not necessarily have to be a device that configures a core network. For example, if the core network is a W-CDMA or cdma2000 core network, the management device 10 may be a device that functions as an RNC (Radio Network Controller).

[0046] Fig. 5 is a diagram showing a configuration example of a management device 10 according to an embodiment of the present disclosure. The management device 10 includes a communication unit 11, a storage unit 12, and a control unit 13. Note that the configuration shown in Fig. 5 is a functional configuration, and the hardware configuration may be different from this. In addition, the functions of the management device 10 may be distributed and implemented in multiple physically separated configurations. For example, the management device 10 may be configured by multiple server devices.

[0047] The communication unit 11 is a communication interface for communicating with other devices. The communication unit 11 may be a network interface or a device connection interface. For example, the communication unit 11 may be a LAN (Local Area Network) interface such as a NIC (Network Interface Card), or a USB (Universal Serial Bus) interface configured with a USB host controller, a USB port, and the like. The communication unit 11 may be a wired interface or a wireless interface. The communication unit 11 functions as a communication means of the management device 10. The communication unit 11 communicates with the base station 30 and the relay station 60 according to the control of the control unit 13.

[0048] The storage unit 12 is a data readable / writable storage device such as a dynamic random access memory (DRAM), a static random access memory (SRAM), a flash memory, or a hard disk. The storage unit 12 functions as a storage means of the management device 10. The storage unit 12 stores, for example, the connection state of the terminal device 50. For example, the storage unit 12 stores the state of the radio resource control (RRC) and the state of the EPS connection management (ECM) of the terminal device 50. The storage unit 12 may function as a home memory that stores location information of the terminal device 50.

[0049] The control unit 13 is a controller that controls each part of the management device 10. The control unit 13 is realized by a processor such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). For example, the control unit 13 is realized by the processor executing various programs stored in a storage device inside the management device 10 using a RAM (Random Access Memory) or the like as a working area. The control unit 13 may be realized by an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array). The CPU, MPU, ASIC, and FPGA can all be considered as controllers.

[0050] <2-3. Base station configuration> Next, the configuration of the base station will be described. The communication system 1 includes base station 20, base station 30, and base station 40 as base stations. All of the base stations 20 to 40 may be mobile. Below, the configuration of base station 20 will be described as an example of the configuration of the base station. Note that the configurations of base station 30 and base station 40 may be the same as the configuration of base station 20 shown below.

[0051] Fig. 6 is a diagram showing a configuration example of the base station 20 according to the embodiment of the present disclosure. The base station 20 includes a wireless communication unit 21, a storage unit 22, and a control unit 23. Note that the configuration shown in Fig. 6 is a functional configuration, and the hardware configuration may be different from this. Furthermore, the functions of the base station 20 may be distributed and implemented in multiple physically separated configurations.

[0052] The wireless communication unit 21 is a wireless communication interface that wirelessly communicates with other wireless terminal devices (for example, the terminal device 50 and the relay station 60). The wireless communication unit 21 supports one or more wireless access methods. For example, the wireless communication unit 21 supports both NR and LTE. The wireless communication unit 21 may support W-CDMA and cdma2000 in addition to NR and LTE. The wireless communication unit 21 includes a reception processing unit 211, a transmission processing unit 212, and an antenna 213. The wireless communication unit 21 may include a plurality of reception processing units 211, a plurality of transmission processing units 212, and a plurality of antennas 213. When the wireless communication unit 21 supports a plurality of wireless access methods, each unit of the wireless communication unit 21 may be configured separately for each wireless access method. For example, the reception processing unit 211 and the transmission processing unit 212 may be configured separately for LTE and NR.

[0053] The reception processing unit 211 processes an uplink signal received via the antenna 213. The reception processing unit 211 includes a radio reception unit 211a, a demultiplexing unit 211b, a demodulation unit 211c, and a decoding unit 211d.

[0054] The wireless receiver 211a performs down-conversion, removal of unnecessary frequency components, control of amplification level, orthogonal demodulation, conversion to digital signal, removal of guard interval, extraction of frequency domain signal by fast Fourier transform, etc., on the uplink signal. The demultiplexer 211b separates uplink channels such as PUSCH (Physical Uplink Shared Channel) and PUCCH (Physical Uplink Control Channel) and uplink reference signals from the signal output from the wireless receiver 211a. The demodulator 211c demodulates the received signal using a modulation method such as BPSK (Binary Phase Shift Keying) and QPSK (Quadrature Phase Shift Keying) for the modulation symbols of the uplink channel. The modulation method used by the demodulator 211c may be 16QAM (Quadrature Amplitude Modulation), 64QAM, or 256QAM, etc. The decoder 211d performs decoding processing on the coded bits of the demodulated uplink channel. The decoded uplink data and uplink control information are output to the control unit 23.

[0055] The transmission processing unit 212 performs a transmission process of the downlink control information and the downlink data, and includes an encoding unit 212a, a modulation unit 212b, a multiplexing unit 212c, and a radio transmission unit 212d.

[0056] The coding unit 212a codes the downlink control information and downlink data input from the control unit 23 using a coding method such as block coding, convolution coding, turbo coding, etc. The modulation unit 212b modulates the coded bits output from the coding unit 212a using a predetermined modulation method such as BPSK, QPSK, 16QAM, 64QAM, 256QAM, etc. The multiplexing unit 212c multiplexes the modulation symbols of each channel and the downlink reference signal, and places them in a predetermined resource element. The wireless transmission unit 212d performs various signal processing on the signal from the multiplexing unit 212c. For example, the wireless transmission unit 212d performs processing such as conversion to the time domain by fast Fourier transform, addition of a guard interval, generation of a baseband digital signal, conversion to an analog signal, quadrature modulation, up-conversion, removal of unnecessary frequency components, and power amplification. The signal generated by the transmission processing unit 212 is transmitted from the antenna 213.

[0057] The storage unit 22 is a storage device capable of reading and writing data, such as a DRAM, an SRAM, a flash memory, or a hard disk. The storage unit 22 functions as a storage means of the base station 20. The storage unit 22 stores switching information. The switching information is information used by the terminal device 50 to switch between base stations. The switching information includes, for example, resource information, trigger information, timing advance information, and other information.

[0058] The resource information is information on radio resources used by the connected terminal device 50 for wireless communication with a switching destination candidate base station configured to be movable. The trigger information is information used by the terminal device 50 to determine whether or not to switch the connection destination base station. The timing advance information is information on a timing advance for the terminal device 50 to connect to the switching destination candidate base station. The resource information, trigger information, and timing advance information will be described in detail later.

[0059] The control unit 23 is a controller that controls each unit of the base station 20. The control unit 23 is realized by a processor such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). For example, the control unit 23 is realized by a processor executing various programs stored in a storage device inside the base station 20 using a RAM (Random Access Memory) or the like as a working area. The control unit 23 may be realized by an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array). The CPU, MPU, ASIC, and FPGA can all be considered as controllers.

[0060] <2-5. Terminal device configuration> Next, the configuration of the terminal device 50 will be described. FIG. 7 is a diagram showing an example of the configuration of the terminal device 50 according to the embodiment of the present disclosure. The terminal device 50 includes a wireless communication unit 51, a storage unit 52, a network communication unit 53, an input / output unit 54, and a control unit 55. The configuration shown in FIG. 7 is a functional configuration, and the hardware configuration may be different from this. The functions of the terminal device 50 may be distributed and implemented in a plurality of physically separated configurations. The configuration shown in FIG. 7 is an example, and the wireless communication unit 51, the storage unit 52, the network communication unit 53, the input / output unit 54, and the control unit 55 are not all essential components. For example, from the viewpoint of the embodiment of the present disclosure, at least the network communication unit 53 and the input / output unit 54 may not be essential components.

[0061] The wireless communication unit 51 is a wireless communication interface that wirelessly communicates with other wireless communication devices (for example, base stations 20, 30, 40). The wireless communication unit 51 supports one or more wireless access methods. For example, the wireless communication unit 51 supports both NR and LTE. The wireless communication unit 51 may support W-CDMA and cdma2000 in addition to NR and LTE. The wireless communication unit 51 includes a reception processing unit 511, a transmission processing unit 512, and an antenna 513. The wireless communication unit 51 may include a plurality of reception processing units 511, a plurality of transmission processing units 512, and a plurality of antennas 513. When the wireless communication unit 51 supports a plurality of wireless access methods, each unit of the wireless communication unit 51 may be configured separately for each wireless access method. For example, the reception processing unit 511 and the transmission processing unit 512 may be configured separately for LTE and NR.

[0062] The reception processing unit 511 processes a downlink signal received via the antenna 513. The reception processing unit 511 includes a radio reception unit 511a, a demultiplexing unit 511b, a demodulation unit 511c, and a decoding unit 511d.

[0063] The wireless receiver 511a performs down-conversion, removal of unnecessary frequency components, control of amplification level, orthogonal demodulation, conversion to digital signal, removal of guard interval, extraction of frequency domain signal by fast Fourier transform, etc., on the downlink signal. The demultiplexer 511b separates the downlink channel, the downlink synchronization signal, and the downlink reference signal from the signal output from the wireless receiver 511a. The downlink channel is, for example, a channel such as PBCH (Physical Broadcast Channel), PDSCH (Physical Downlink Shared Channel), or PDCCH (Physical Downlink Control Channel). The demodulator 211c demodulates the received signal using a modulation method such as BPSK, QPSK, 16QAM, 64QAM, or 256QAM for the modulation symbols of the downlink channel. The decoder 511d performs decoding processing on the coded bits of the demodulated downlink channel. The decoded downlink data and downlink control information are output to the controller 23.

[0064] The transmission processing unit 512 performs a transmission process of the uplink control information and the uplink data, and includes an encoding unit 512a, a modulation unit 512b, a multiplexing unit 512c, and a radio transmission unit 512d.

[0065] The coding unit 512a codes the uplink control information and uplink data input from the control unit 55 using a coding method such as block coding, convolution coding, turbo coding, etc. The modulation unit 512b modulates the coded bits output from the coding unit 512a using a predetermined modulation method such as BPSK, QPSK, 16QAM, 64QAM, 256QAM, etc. The multiplexing unit 512c multiplexes the modulation symbols of each channel and the uplink reference signal, and places them in a predetermined resource element. The wireless transmission unit 512d performs various signal processing on the signal from the multiplexing unit 512c. For example, the wireless transmission unit 512d performs processing such as conversion to the time domain by inverse fast Fourier transform, addition of a guard interval, generation of a baseband digital signal, conversion to an analog signal, quadrature modulation, up-conversion, removal of unnecessary frequency components, and power amplification. The signal generated by the transmission processing unit 512 is transmitted from the antenna 513.

[0066] The storage unit 52 is a storage device capable of reading and writing data, such as a DRAM, an SRAM, a flash memory, or a hard disk. The storage unit 52 functions as a storage means of the terminal device 50. The storage unit 52 stores switching information. The switching information is information acquired from the base station 20, 30, or 40, and is used by the terminal device 50 to switch between base stations. The switching information includes, for example, resource information, trigger information, timing advance information, and other information. The resource information, trigger information, and timing advance information will be described in detail later.

[0067] The network communication unit 53 is a communication interface for communicating with other devices. For example, the network communication unit 53 is a LAN interface such as a NIC. The network communication unit 53 may be a wired interface or a wireless interface. The network communication unit 53 functions as a network communication means of the terminal device 50. The network communication unit 53 communicates with other devices under the control of the control unit 55.

[0068] The input / output unit 54 is a user interface for exchanging information with the user. For example, the input / output unit 54 is an operation device such as a keyboard, a mouse, an operation key, or a touch panel that allows the user to perform various operations. Alternatively, the input / output unit 54 is a display device such as a liquid crystal display (LCD) or an organic electroluminescence display (OLED). The input / output unit 54 may be an audio device such as a speaker or a buzzer. The input / output unit 54 may also be a lighting device such as an LED (Light Emitting Diode) lamp. The input / output unit 54 functions as an input / output means (input means, output means, operation means, or notification means) of the terminal device 50.

[0069] The control unit 55 is a controller that controls each unit of the terminal device 50. The control unit 55 is realized by a processor such as a CPU or an MPU. For example, the control unit 55 is realized by the processor executing various programs stored in a storage device inside the terminal device 50 using a RAM or the like as a working area. The control unit 55 may be realized by an integrated circuit such as an ASIC or an FPGA. The CPU, the MPU, the ASIC, and the FPGA can all be considered as controllers.

[0070] <2-6. Initial connection process> Next, a description will be given of the operation of the communication system 1. First, a description will be given of an initial connection process. The initial connection (Initial Access) is a process for transitioning a UE (terminal device 50) from an idle state (RRC_IDLE) in which a connection has not been established with any RAN (base station) base station 20 or base station 30 to a connected state (RRC_CONNECTED) in which a connection with any RAN has been established.

[0071] Fig. 8 is a flowchart showing an example of the initial connection process. The initial connection process will be described below with reference to Fig. 8. The initial connection process shown below is executed, for example, when the UE (terminal device 50) is powered on.

[0072] First, the terminal device 50 in an idle state performs a cell search. The cell search is a procedure for a UE to detect a physical cell ID (PCI) of a cell and obtain time and frequency synchronization. The cell search of this embodiment includes a process of detecting a synchronization signal and decoding a PBCH. The synchronization signal (SS) in NR includes a Primary Synchronization Signal (PSS) and a Secondary Synchronization Signal (SSS). In NR, the PSS, SSS, and PBCH are transmitted as one set. This set is called an SS / PBCH block (SSB). In addition, a plurality of SSBs are transmitted per unit time (e.g., half frame (5 ms)). A plurality of SSBs transmitted per half frame are called an SSB burst, an SS burst, an SSB burst set, or an SS burst set. An SSB burst is transmitted periodically and repeatedly with the periodicity of the SSB burst. An index (SSB index) is assigned to each of the plurality of SSBs in one SSB burst. One SSB index is associated with, for example, one beam. Furthermore, the number of SSBs in one SSB burst depends on the Subcarrier Spacing associated with the frequency band. The control unit 55 of the UE (terminal device 50) detects the SSB of the cell (step S101). More specifically, the UE detects the SSB corresponding to the beam with the best quality from among the SSB bursts. The control unit 55 performs downlink synchronization with the cell based on the detected synchronization signal. After downlink synchronization is established, the control unit 55 attempts to decode the PBCH and acquires the MIB (Master Information Block), which is part of the system information (step S102).

[0073] The system information is information that broadcasts settings in a cell that transmits the system information. The system information includes, for example, information (eg, RACH-Config) related to cell access (eg, Random Access), information related to cell selection, information related to other RATs and other systems, and the like. The system information includes MIB and SIB (System Information Block). The MIB is physical layer information required to receive SIBs and the like, and is information on a fixed payload size broadcast by the PBCH. The MIB includes a downlink system bandwidth, a part of the system frame number, SIB scheduling information, and the like. The SIB is system information other than the MIB, and is broadcast by the PDSCH.

[0074] The system information can be classified into first system information, second system information, and third system information. The first system information and second system information include information on access to a cell, information on acquisition of other system information, and information on cell selection. In LTE, information included in MIB is the first system information. Also, information included in SIB1 and SIB2 of the SIB is the second system information. The remaining system information is the third system information.

[0075] In NR, system information is also broadcast from an NR cell. A physical channel carrying the system information may be transmitted in a slot or a minislot. A minislot is defined as a number of symbols less than the number of symbols in a slot. By transmitting a physical channel carrying the system information in a minislot, the time required for beam sweeping is shortened, and overhead can be reduced. In the case of NR, the first system information is transmitted in the NR-PBCH, and the second system information is transmitted in a physical channel different from the NR-PBCH.

[0076] The control unit 55 of the terminal device 50 acquires the second system information based on the MIB (i.e., the first system information) (step S103). As described above, the second system information is composed of SIB1 and SIB2. SIB1 is cell access restriction information and scheduling information of system information other than SIB1. In the case of NR, SIB1 includes information on cell selection (e.g., cellSelectionInfo), information related to cell access (e.g., cellAccessRelatedInfo), information on connection establishment failure control (e.g., connEstFailureControl), scheduling information of system information other than SIB1 (e.g., si-SchedulingInfo), and a serving cell configuration. The serving cell configuration includes cell-specific parameters, and includes downlink configuration, uplink configuration, TDD configuration information, and the like. The uplink configuration includes RACH configuration, and the like. In the case of LTE, SIB1 includes cell access information, cell selection information, maximum uplink transmission power information, TDD setting information, system information period, system information mapping information, SI (System Information) window length, etc. In the case of NR, SIB2 includes cell reselection information (e.g., cellReselectionInfoCommon) and cell reselection serving frequency information (e.g., cellReselectionServingFreqInfo). In the case of LTE, SIB2 includes connection prohibition information, cell-common radio resource setting information (radioResourceConfigCommon), uplink carrier information, etc. The cell-common radio resource setting information includes setting information of a cell-common PRACH (Physical Random Access Channel) and RACH (Random Access Channel).

[0077] If the control unit 55 is unable to acquire system information necessary for establishing a link, the control unit 55 of the terminal device 50 determines that access to the cell is prohibited. For example, if the control unit 55 is unable to acquire all of the first system information and the second system information, the control unit 55 determines that access to the cell is prohibited. In this case, the control unit 55 ends the initial connection process.

[0078] If the system information can be acquired, the control unit 55 executes a random access procedure based on the first system information and / or the second system information (step S104). The random access procedure may be called a random access channel procedure (RACH procedure) or an RA procedure. In the RACH procedure, the UE first transmits a random access preamble, and then monitors the PDCCH of the cell for a random access response identified by the RA-RNTI only for a period indicated by the set IE ra-ResponseWindow. On the other hand, if the transmitted preamble reaches the RAN without collision, a random access response including a preamble identifier corresponding to PREAMBLE_INDEX, which is an index of the transmitted preamble, is transmitted from the RAN to the UE. If the UE receives a random access response including a preamble identifier corresponding to the transmitted PREAMBLE_INDEX while the ra-ResponseWindow is running, the UE recognizes that the random access procedure has been completed successfully. Then, the UE sends an RRC Setup Request message in Msg3, and when it receives an RRC Setup message from the RAN in response to the RRC Setup Request message, the UE (terminal device 50) transitions from an idle state (RRC_IDLE) to a connected state (RRC_CONNECTED) (enters RRC Connected) and recognizes the current cell (the cell that performed the RACH procedure and the RRC Setup procedure) as the Primary Cell.

[0079] <2-7. An example of HARQ procedure> Here, in communication processing (for example, the above-mentioned initial connection processing) by the control unit 55 of the terminal device 50 and the control unit (for example, the control unit 23) of the base station device (for example, the base station 20, the base station 30), Hybrid ARQ (HARQ) is used for data error correction. For example, HARQ is used for PDSCH data transmission, PUSCH data transmission, and PSSCH data transmission.

[0080] HARQ is a means for obtaining coding gain by combining (soft combining) data that is initially transmitted and data that is retransmitted, and performing error correction. In order to perform HARQ, the base station apparatus or terminal apparatus 50 stores data that has failed to be decoded in a HARQ buffer, combines the retransmitted data with the stored data, and performs error correction. More specifically, one HARQ process may include the following operations. A MAC entity in a UE (terminal apparatus 50) determines whether the received data is a new transmission or a retransmission from a New Date Indicator (NDI) in a DCI that schedules a transmission resource for the data. If the received data is a new transmission, the MAC entity attempts to decode the received data. If the received data is a retransmission, and if the data of the transport block has not yet been successfully decoded, the MAC entity instructs the physical layer to combine the data currently in the soft buffer for this transport block with the received data, and attempts to decode the combined data. If the data attempted to be decoded by the MAC entity is successfully decoded or if data was previously successfully decoded, the decoded MAC PDU is delivered to a higher layer or disassembly and demultiplexing entity. If the data attempted to be decoded by the MAC entity is not successfully decoded and if data was previously not successfully decoded, the MAC entity instructs the physical layer to replace the data in the soft buffer for that transport block with the data attempted to be decoded. The MAC entity then instructs the physical layer to generate acknowledgement(s), i.e., HARQ Feedback (ACK / NACK), for the data in that transport block.

[0081] The HARQ process is performed for each HARQ process to which identification information (e.g., HARQ process identifier) ​​is assigned. That is, when there are multiple HARQ processes, it is possible to perform HARQ processes in parallel. The base station device or the terminal device 50 can hold one or multiple HARQ processes. More specifically, the MAC entity includes a HARQ entity for each serving cell. The HARQ entity maintains multiple parallel HARQ processes. The HARQ process can be applied not only to the downlink but also to the uplink. In this case, the MAC entity includes a HARQ entity for each serving cell in which an uplink is configured. As described above, each HARQ process is associated with a HARQ process identifier. The number of HARQ processes for the downlink and the number of HARQ processes for the uplink may be different or the same. The HARQ entity, for example, transfers HARQ information and related TB to the corresponding HARQ process.

[0082] The base station device in the following description can be implemented regardless of whether it is a base station 20 that operates as a communication device, such as a satellite station, a drone, a balloon, or an airplane, or a base station 30. Base station 30 Terminal device Also, when showing specific examples in the following description, there are some places where specific values ​​are shown and explained, but the values ​​are not limited to those examples and other values ​​may be used.

[0083] In the following description, the resource represents Frequency, Time, Resource Element (including REG, CCE, and CORESET), Resource Block, Bandwidth Part, Component Carrier, Symbol, Sub-Symbol, Slot, Mini-Slot, Subslot, Subframe, Frame, PRACH occasion, Occasion, Code, Multi-access physical resource, Multi-access signature, Subcarrier Spacing (Numerology), etc. In the following description, the HARQ process identifier may be read as the HARQ process number.

[0084] Here, the HARQ procedure will be described by taking as an example PDSCH data transmission from a base station device (for example, base stations 20 and 30) to a terminal device 50. Fig. 9 is a sequence diagram showing an example of the HARQ procedure.

[0085] As shown in FIG. 9, a control unit (e.g., control unit 23) of a base station device (e.g., base station 20, base station 30) transmits PDSCH data to a terminal device 50 by using HARQ via wireless communication (e.g., wireless communication unit 21) (step S201). That is, the UE (terminal device 50) receives the PDSCH data. More specifically, the UE monitors the PDCCH in a period determined based on a configuration related to PDCCH monitoring, such as Discontinuous Reception (DRX), BWP, and SCell configuration. Here, if there is data addressed to the UE (i.e., if the PDCCH indicates allocation of data (PDSCH) addressed to the UE), the UE receives the data on the corresponding PDSCH. Then, the UE starts a drx-HARQ-RTT-TimerDL for the HARQ process associated with the data (Transport Block carried by the PDSCH) triggered by the PDCCH indicating PDSCH data (DL transmission). The timing for starting drx-HARQ-RTT-TimerDL is the first OFDM symbol after the last OFDM symbol of the corresponding transmission carrying DL HARQ feedback. The HARQ process for this PDSCH data transmission shall be assigned HARQ process #1 as the HARQ process identifier.

[0086] The control unit 55 (eg, MAC entity) of the terminal device 50 that has received the PDSCH data from the base station device attempts to decode the PDSCH data (ie, data in a transport block carried by the PDSCH). As described above, if the received data is a new transmission, new decoding is attempted, and if the received data is a retransmission, decoding is attempted after combining the data already stored in the soft buffer with the received data. Here, it is assumed that the decoding of the PDSCH data has failed (not successfully decoded) (step S202).

[0087] Due to the failure of decoding the PDSCH data, the control unit 55 (eg, MAC entity) of the terminal device 50 stores the unsuccessfully decoded PDSCH data in the HARQ buffer of the HARQ process #1 in the storage area secured in the storage unit 52 (step S204). If the data has already been stored in the HARQ buffer, it is replaced. Next, a NACK is transmitted to the base station device via the wireless communication unit 51 (step S203). Furthermore, if the drx-HARQ-RTT-TimerDL that was being operated expires, the terminal device UE starts the drx-RetransmissionTimerDL if the data of the HARQ process has not been successfully decoded. The timing for starting the drx-RetransmissionTimerDL is the first OFDM symbol after the expiration of the drx-HARQ-RTT-TimerDL. In the case of FIG. 9, in step S202, the decoding of the data corresponding to the HARQ process #1 has failed, so the drx-RetransmissionTimerDL starts.

[0088] Fig. 10 is an explanatory diagram for explaining an outline of the HARQ buffer. As shown in Fig. 10, a storage area 521 is allocated to each HARQ process in the storage unit 52. This allows the terminal device 50 to hold one or more HARQ processes. Note that, like the terminal device 50, the base station device (e.g., the base station 20, the base station 30) is also capable of holding one or more HARQ processes in a storage unit (e.g., the storage unit 22).

[0089] In the illustrated example, the control unit 55 stores the PDSCH data in the HARQ buffer 522a in the storage area 522 of the HARQ process #1 related to the PDSCH data that has failed to be decoded. If the data has already been stored in the HARQ buffer, it is replaced.

[0090] Returning to FIG. 9, a control unit (e.g., control unit 23) of a base station device (e.g., base station 20, base station 30) that receives the NACK retransmits the PDSCH data to the terminal device 50 via wireless communication (e.g., wireless communication unit 21) (step S205). In other words, the UE (terminal device 50) receives the retransmission of the PDSCH data. More specifically, the UE monitors the PDCCH while drx-RetransmissionTimerDL is operating. The drx-RetransmissionTimerDL indicates the time at which the UE expects a DL retransmission from the RAN. Thus, a DL retransmission is sent to the UE while the drx-RetransmissionTimerDL is operating.

[0091] The control unit 55 of the terminal device 50 that has received the retransmitted PDSCH data performs soft combining of the data stored in the HARQ buffer 522a of the HARQ process #1 and the retransmitted data to decode the PDSCH data (step S206). Here, it is assumed that the decoding of the PDSCH data is successful (step S207).

[0092] If the PDSCH data is successfully decoded, the control unit 55 of the terminal device 50 transmits an ACK to the base station device via the wireless communication unit 51 (step S208). Next, the control unit 55 of the terminal device 50 clears the data in the HARQ buffer 522a of HARQ process #1 (step S209).

[0093] <2-8. Transmission delay problem> For example, in the case of NTN communication, the propagation distance between the terminal device 50 and a base station device (for example, base station 20, base station 30) including an airplane or a drone is long, so the propagation delay is large.

[0094] When the propagation delay is large, the HARQ buffer of the base station apparatus or terminal apparatus 50 may run out of space, resulting in a shortage of the number of HARQ processes. For example, when the base station apparatus transmits data and the terminal apparatus 50 receives the data, if decoding is successful, the terminal apparatus 50 returns an ACK to the base station apparatus, flushes (clears) the data in the HARQ buffer, and the process ends. On the other hand, if decoding fails, the terminal apparatus 50 returns a NACK to the base station apparatus, and needs to hold the received data in the HARQ buffer in order to perform soft combining with the data retransmitted after the NACK return.

[0095] The base station device and terminal device 50 can use one or more HARQ processes in parallel, and when the propagation delay is small, the time from returning NACK to transmitting retransmitted data is short, and there is no problem of a shortage of HARQ processes. However, when the propagation delay is large, the time from returning NACK to retransmission becomes long, and there is a possibility that there will be a shortage of HARQ processes (or it will take time to resolve the shortage state).

[0096] <2-9. Overview of the embodiment> In consideration of the above-mentioned transmission delay problem, in the base station device and terminal device 50 in this embodiment, under the control of a control unit (e.g., control units 23, 55), disable information for disabling feedback for retransmission in HARQ is notified via a wireless communication unit (e.g., wireless communication units 21, 51) (HARQ feedback disabling). In this way, by disabling feedback for retransmission (HARQ feedback disabling), received data is not stored in the HARQ buffer, and the data in the buffer is immediately flushed (cleared), so that the HARQ process does not run short.

[0097] HARQ feedback disabling means that only the initial transmission or repeated transmission is performed for a single or multiple spatially multiplexed Transport blocks, and data transmission is completed without an ACK / NACK notification from the terminal device 50. At this time, the terminal device 50 does not need to return an ACK / NACK.

[0098] For example, when downlink is taken into consideration, HARQ feedback for PDSCH transmission corresponds to UCI (Uplink Control Information) transmitted from the terminal device 50. As an example, if decoding of the PDSCH transmitted from a base station device (e.g., base station 20, base station 30) fails, the control unit 55 of the terminal device 50 transmits UCI (NACK) to the base station device via the wireless communication unit 51. As a result, the control unit (e.g., control unit 23) of the base station device retransmits the data via the wireless communication unit (e.g., wireless communication unit 21). On the other hand, if decoding of the PDSCH transmitted from the base station device is successful, the control unit 55 of the terminal device 50 transmits UCI (ACK) to the base station device via the wireless communication unit 51, and the base station device transmits the next new data.

[0099] Also, when uplink is taken into consideration, HARQ feedback for PUSCH transmission corresponds to, for example, DCI (Downlink Control Information) transmitted from a base station device, or corresponds to explicit ACK / NACK information. For example, if decoding of the PUSCH transmitted from the terminal device 50 fails, a control unit (e.g., control unit 23) of the base station device transmits DCI including information indicating retransmission to the terminal device 50 via a wireless communication unit (e.g., wireless communication unit 21). As a result, the control unit 55 of the terminal device 50 retransmits the data. On the other hand, if decoding of the PUSCH transmitted from the terminal device 50 is successful, a control unit (e.g., control unit 23) of the base station device transmits DCI including information indicating initial transmission to the terminal device 50 via a wireless communication unit (e.g., wireless communication unit 21). As a result, the control unit 55 of the terminal device 50 transmits the next new data.

[0100] Also, when the side link is taken into consideration, the HARQ feedback for the PSSCH transmission corresponds to SCI (Sidelink Control Information) or ACK / NACK information transmitted from the terminal device 50. For example, if decoding of the PSSCH transmitted from the terminal device 501 fails, the control unit 55 of the terminal device 502 transmits an SCI including information indicating retransmission to the terminal device 501 via the wireless communication unit 51. As a result, the control unit 55 of the terminal device 501 retransmits the data via the wireless communication unit 51. On the other hand, if decoding of the PSSCH transmitted from the terminal device 501 is successful, the control unit 55 of the terminal device 502 transmits an SCI including information indicating initial transmission to the terminal device 501 via the wireless communication unit 51. As a result, the control unit 55 of the terminal device 501 transmits the next new data via the wireless communication unit 51.

[0101] Also, for example, if decoding of the PSSCH transmitted from the terminal device 501 fails, the control unit 55 of the terminal device 502 transmits a NACK to the terminal device 501 via the wireless communication unit 51. As a result, the control unit 55 of the terminal device 501 retransmits the data via the wireless communication unit 51. On the other hand, if decoding of the PSSCH transmitted from the terminal device 501 is successful, the control unit 55 of the terminal device 502 transmits an ACK to the terminal device 501 via the wireless communication unit 51. As a result, the control unit 55 of the terminal device 501 transmits the next new data via the wireless communication unit 51.

[0102] As described above, HARQ feedback corresponds to information such as the UCI, DCI, SCI, and ACK / NACK information. When HARQ feedback disabling is performed, the base station apparatus (e.g., base station 20, base station 30) and the terminal apparatus 50 can transmit and receive the next new data without waiting for the transmission and reception of the UCI, DCI, SCI, and ACK / NACK information. At this time, the HARQ buffer of the base station apparatus (e.g., base station 20, base station 30) and the terminal apparatus 50 does not need to hold the transmission and reception data. Note that HARQ feedback disabling / enabling is applicable to any of the downlink, uplink, and sidelink, and is not limited to any one of them.

[0103] In this embodiment, the configuration in which HARQ feedback disabling is performed for each HARQ process is illustrated, but the unit for performing HARQ feedback disabling may be set appropriately. For example, in addition to each HARQ process, HARQ feedback disabling may be performed for each cell, each beam, each component carrier, each BWP (BandWidth Part), or each UE (User Equipment). Specifically, the unit for performing HARQ feedback disabling can be appropriately changed by replacing the HARQ process illustrated in this embodiment with cell, sector, beam, component carrier, BWP, and UE.

[0104] For example, in cell / sector units, enable / disable of HARQ feedback may be switched for each serving cell (i.e., for each HARQ entity). In other words, enable / disable of HARQ feedback may be switched for multiple terminals in a cell at a common configuration or timing. Furthermore, in beam (i.e., SSB or CSI-RS) units, enable / disable of HARQ feedback may be switched for each transmission beam or each reception beam. Furthermore, in component carrier units, enable / disable of HARQ feedback may be switched for each component carrier. Furthermore, in Bandwidth Part (BWP) units, enable / disable of HARQ feedback may be switched for each BWP. Furthermore, in UE units, enable / disable of HARQ feedback may be switched for each terminal. Furthermore, in HARQ process units, enable / disable of HARQ feedback may be switched for each HARQ process (i.e., for each TB). Furthermore, in packet units, enable / disable of HARQ feedback may be switched for each transmission packet. The above units may be combined and switched.

[0105] Here, a specific example of HARQ feedback disabling processing for each HARQ process will be described for each of the downlink and uplink.

[0106] <2-10. An example of HARQ disabling processing (downlink)> Fig. 11 is a sequence diagram showing an example of a HARQ disabling process according to an embodiment of the present disclosure. Specifically, Fig. 11 illustrates a HARQ feedback disabling process for each HARQ process in a downlink. In the example of Fig. 11, HARQ feedback is enabled for HARQ process #1, and HARQ feedback is disabled for HARQ process #2.

[0107] As shown in FIG. 11, first, a control unit (e.g., the control unit 23) of a base station device (e.g., the base station 20, the base station 30) sends a notification to the UE (terminal device 50) to disable a specific HARQ process via wireless communication (e.g., the wireless communication unit 21) as a trigger for HARQ feedback disabling (step S301).

[0108] Specifically, in step S301, the base station device performs a notification of disabling HARQ feedback of HARQ process #2. This notification includes, for example, a semi-static notification (for example, RRC (Radio Resource Control) signaling (e.g., RRC Reconfiguration message, RRC Setup message, RRC Resume message)) and a dynamic notification (e.g., DCI). A control unit (e.g., control unit 23) of a base station device (e.g., base station 20, base station 30) may perform any of the above notification methods. In addition, when a UE (terminal device 50) performs Dual Connectivity with multiple base stations, the semi-static notification may be received from the MN via SRB0, 1, and 2, or may be directly received from the SN via SRB3. In addition, the dynamic notification may be directly received from each of the MN and SN. For example, in the case of ENDC, a semi-static notification generated by the SN may be transmitted to the MN via the X2 interface and provided from the MN to the UE by RRC signaling. Furthermore, in the case of ENDC, the dynamic notification may be provided to the UE independently from the PHY layer hosted by the MN and the PHY layer hosted by the SN. Note that the semi-static notification and the dynamic notification may be performed either alone or in combination. The semi-static notification may be transmitted to the UE by broadcast information (e.g., MIB, SIB).

[0109] Semi-static notification includes a method of explicitly notifying HARQ disabling and a method of implicitly notifying HARQ disabling. In the explicit notification, for example, HARQ disable is notified by System information / RRC signaling.

[0110] In the implicit notification, the terminal device 50 performs notification to determine whether or not to disable HARQ feedback based on other information notified by system information or RRC signaling. For example, in the implicit notification, the terminal device 50 may determine (recognize) disabling based on the following information in the system information or the like. Location information of the base station device and the terminal device 50 Propagation distance and propagation delay information between the base station device and the terminal device 50 Altitude of the base station device and the terminal device 50 The moving speed of the base station device and the terminal device 50 Timing advance information Power control information

[0111] For example, the control unit 55 of the terminal device 50 disables HARQ feedback when the Timing advance is greater than a predetermined value, and enables HARQ feedback when the Timing advance is less than a predetermined value.

[0112] Furthermore, the control unit 55 of the terminal device 50 may determine whether to disable HARQ feedback based on information on power control. For example, the control unit 55 of the terminal device 50 disables HARQ feedback when power control is greater than a predetermined value. Furthermore, the control unit 55 of the terminal device 50 enables HARQ feedback when power control is less than a predetermined value.

[0113] In dynamic notification, for example, when an HARQ process has been exhausted or when it is determined that there is a possibility of exhaustion, HARQ feedback for all or some of the HARQ processes is disabled (introducing dynamic HARQ disabling).

[0114] Note that the dynamic notification includes a method of explicitly notifying HARQ disabling and a method of implicitly notifying HARQ disabling.

[0115] Explicit methods include, for example, the following: -Add HARQ disabling field to DCI - Notify HARQ disabling request via UCI Here, the HARQ disabling request is notification information for the terminal device 50 to request HARQ disabling to the base station device. The base station device that receives the HARQ disabling request may perform HARQ disabling based on the notified information. -Notify HARQ Feedback of Transport blocks that should not be stopped and Transport blocks that can be stopped

[0116] Examples of implicit methods include the following: -Notified by other physical information of PDCCH (CORESET, search space, scrambling (DMRS, RNTI)) ·Notification by Reference signal sequence / port Switch with DMRS sequence initialization Switching via Antenna port

[0117] In addition, when dynamically disabling HARQ, a control unit (e.g., the control unit 23) of the base station device or a control unit 55 of the terminal device 50 may perform an operation of dynamically enabling the disabled HARQ feedback. In addition, the timing of the disable / enable may be specified by a standard, or may be notified from the RAN to the UE.

[0118] For example, the operation of dynamically disabling / enabling HARQ feedback may be applied under the following conditions (a-1, a-2, b-1, b-2). (a-1) Applied from subframe n (or slot n) in which DCI including disabling / enabling indication was received (a-2) Applies from subframe n to subframe n+k (or from slot n to slot n+k) when DCI including disabling / enabling indication is received (e.g., k=4) (b-1) Apply from the process indicated by the HARQ process number indicated by the DCI including the disabling / enabling indication (b-2) Applied from the next process indicated by the HARQ process number indicated by the DCI including the disabling / enabling indication

[0119] The base station may notify the UE by semi-static or dynamic notification that at least one of the above (a-1) to (b-2) is applied. In addition, the value of k in the above (a-2) may also be notified by semi-static or dynamic notification to the UE.

[0120] Furthermore, a control unit (eg, the control unit 23) of a base station device (eg, the base station 20, the base station 30) may select a target for which HARQ feedback disabling is to be performed.

[0121] For example, when a control unit (e.g., the control unit 23) of a base station device (e.g., the base station 20, the base station 30) disables HARQ feedback on a cell, sector, or beam basis, the terminal device 50 belonging to the cell, sector, or beam for which HARQ feedback disable is to be the target of HARQ feedback disable. Then, the control unit (e.g., the control unit 23) notifies the target terminal device 50 of disabling of HARQ feedback. If the target of HARQ feedback disable is all terminal devices in the cell (i.e., if HARQ feedback disable is set in Cell specific), the notification may be made using system information. Also, if the target of HARQ feedback disable is dedicated to a specific terminal device (i.e., if HARQ feedback disable is set in UE specific), the notification may be made using dedicated RRC signaling (e.g., RRCReconfiguration message, RRCSetup message, RRCResume message). The dedicated RRC signaling may include one or more configurations in which HARQ feedback disable is performed on a serving cell basis or on a beam (eg, SSB, CSI-RS) basis.

[0122] Furthermore, when a control unit (e.g., the control unit 23) of a base station device (e.g., the base station 20, the base station 30) disables HARQ feedback on a component carrier or BWP basis, the control unit (e.g., the control unit 23) sets the component carrier for which HARQ feedback disable is to be performed and the terminal device 50 that communicates via the BWP as a target for HARQ feedback disable. Then, the control unit (e.g., the control unit 23) notifies the target terminal device 50 of the disabling of HARQ feedback by RRC signaling or DCI.

[0123] Furthermore, when a control unit (e.g., the control unit 23) of a base station device (e.g., the base station 20, the base station 30) disables HARQ feedback on a UE-by-UE basis, the UE for which HARQ feedback disable is to be performed is treated as a target for HARQ feedback disable. Then, the control unit (e.g., the control unit 23) notifies the terminal device 50 of the target UE of disabling HARQ feedback by RRC signaling or DCI.

[0124] Furthermore, when disabling HARQ feedback on an HARQ process basis, a control unit (eg, control unit 23) of a base station device (eg, base station 20, base station 30) disables HARQ feedback in the HARQ process in which HARQ feedback disable is performed.

[0125] For example, it is assumed that there are a total of X HARQ processes (here, the HARQ process is used as an example, but the HARQ process may be interpreted as a cell, sector, beam, component carrier, BWP, or UE).

[0126] First, HARQ feedback in (XA) HARQ processes is left enabled, and HARQ feedback in A HARQ processes is disabled, where the value of A is notified explicitly or implicitly.

[0127] For example, an explicit notification of the value of A may be any of the following: -Notification by SIB (System Information Block) -Notification by RRC signaling -Notify by DCI

[0128] Also, the implicit notification of the value of A may be any of the following: -Notified by other physical information of PDCCH (CORESET, search space, scrambling (DMRS, RNTI)) ·Notification by Reference signal sequence / port -Notification of base station type

[0129] In addition, when reporting by base station type, for example, if the base station is GEO, A=X, if it is MEO, A=Y (Y<=X), if it is LEO, A=Z (Z<=Y), etc.

[0130] Alternatively, instead of the number of HARQ processes, the HARQ process numbers to be disabled may be explicitly notified. For example, HARQ process IDs=14 and 15 may be disabled in the notification of the HARQ process numbers to be disabled.

[0131] Also, in addition to X HARQ processes, B HARQ processes for disabling may be added. Since it is considered that there is no need to store data in the HARQ buffer for the disabled HARQ process, it is possible to add a HARQ process for disabling in addition to the existing HARQ process. Note that the number of added B processes may be one or more.

[0132] Although the above description has been given of a HARQ process for disabling, since retransmission processing is not performed, it does not have to be included in one of the HARQ processes. In other words, it may be treated as a process for disabling, separate from the HARQ process.

[0133] Furthermore, when HARQ feedback is set to Disable, as an exception, it may not be disabled in the following cases. UL transmission using the UL grant of the random access response uses HARQ process identifier 0, but this transmission does not disable HARQ feedback even if it is included in the conditions for disabling HARQ feedback. · If the New data indicator in the DCI carried in the PDCCH corresponding to the HARQ process does not indicate New data (New data indicator bit = 0), the HARQ feedback may not be disabled.

[0134] In addition, in the DCI notification when HARQ feedback is disabled, there is a 4-bit notification area (HARQ process number) for notifying the HARQ process identifier, and a 1-bit notification area (New Data Indicator: NDI) for notifying either the first transmission or retransmission. Note that, when HARQ feedback is disabled in all HARQ processes (such as disabling on a cell-by-cell or component carrier-by-component carrier basis), this notification area becomes unnecessary. Such unnecessary notification areas can be used for zero padding, other purposes, etc. For example, such unnecessary notification areas may be used as notification areas for information related to error rate performance compensation means, which will be described below.

[0135] Next, a control unit (e.g., control unit 23) of the base station device (e.g., base station 20, base station 30) transmits DCI and PDSCH data (hereinafter, PDSCH data) to the terminal device 50 using HARQ via wireless communication (e.g., wireless communication unit 21) (step S302). It is assumed that HARQ process #1 is assigned as a HARQ process identifier to the HARQ processing of this data transmission. The control unit (e.g., control unit 23) of the base station device (e.g., base station 20, base station 30) holds the transmitted PDSCH data in the HARQ buffer of HARQ process #1 in a storage unit (e.g., storage unit 22) (step S303).

[0136] The control unit 55 of the terminal device 50 that has received the PDSCH data of HARQ process #1 from the base station device decodes the PDSCH data. Furthermore, the UE (terminal device 50) starts the drx-HARQ-RTT-TimerDL in response to the reception of the PDSCH data (i.e., the PDCCH that scheduled the PDSCH indicated DL transmission). Here, it is assumed that the decoding of the PDSCH data of HARQ process #1 has failed (step S304).

[0137] Due to the failure in decoding the PDSCH data in HARQ process #1, the control unit 55 of the terminal device 50 transmits a NACK of HARQ process #1 to the base station device via the wireless communication unit 51 (step S305). Next, the control unit 55 of the terminal device 50 stores the unsuccessfully decoded PDSCH data in the HARQ buffer 522a of HARQ process #1 in the storage unit 52 (step S306).

[0138] Next, a control unit (eg, control unit 23) of a base station device (eg, base station 20, base station 30) transmits PDSCH data of HARQ process #2 to the terminal device 50 via wireless communication (eg, wireless communication unit 21) (step S307).

[0139] In this HARQ process #2, retransmission processing is disabled (HARQ feedback disabling). Therefore, a control unit (e.g., control unit 23) of a base station device (e.g., base station 20, base station 30) does not hold the transmitted PDSCH data in the HARQ buffer of HARQ process #2 in a storage unit (e.g., storage unit 22) (step S308).

[0140] The control unit 55 of the terminal device 50 that has received the PDSCH data of HARQ process #2 from the base station device decodes the PDSCH data. Here, it is assumed that the decoding of the PDSCH data of HARQ process #2 has failed (step S309).

[0141] For HARQ process #2, retransmission processing is disabled in advance notification (step S301). Therefore, the control unit 55 of the terminal device 50 does not hold the PDSCH data that has failed to be decoded in the HARQ buffer of HARQ process #2 in the storage unit 52 (step S310). Furthermore, even if the PDCCH that scheduled the received PDSCH data indicates DL transmission, the UE (terminal device 50) does not start the drx-HARQ-RTT-TimerDL if the feedback of the corresponding HARQ process is disabled. That is, in this case, the drx-HARQ-RTT-TimerDL corresponding to HARQ process #2 is not started. In other words, when the PDCCH for the UE indicates DL transmission, the UE (terminal device 50) may determine whether or not HARQ feedback in the corresponding HARQ process is disabled, and if it is disabled, not start the drx-HARQ-RTT-TimerDL, and if it is enabled, start the drx-HARQ-RTT-TimerDL.

[0142] A control unit (eg, control unit 23) of a base station device (eg, base station 20, base station 30) that receives the NACK of HARQ process #1 retransmits the PDSCH data to the terminal device 50 via wireless communication (eg, wireless communication unit 21) (step S311).

[0143] The control unit 55 of the terminal device 50 that has received the retransmitted PDSCH data performs soft combining of the data stored in the HARQ buffer 522a of the HARQ process #1 and the retransmitted data to decode the PDSCH data (step S312). Here, it is assumed that the decoding of the PDSCH data has been successful (step S313).

[0144] If the PDSCH data is successfully decoded, the control unit 55 of the terminal device 50 transmits an ACK for HARQ process #1 to the base station device via the wireless communication unit 51 (step S314). The control unit (e.g., the control unit 23) of the base station device (e.g., the base station 20, the base station 30) that has received the ACK for HARQ process #1 clears the data in the HARQ buffer for HARQ process #1 in the storage unit (e.g., the storage unit 22) (step S315). Similarly, the control unit 55 of the terminal device 50 that transmitted the ACK for HARQ process #1 clears the data in the HARQ buffer 522a for HARQ process #1 (step S316).

[0145] <2-11. An example of HARQ disabling processing (uplink)> Fig. 12 is a sequence diagram showing an example of a HARQ disabling process according to an embodiment of the present disclosure. Specifically, Fig. 12 illustrates a HARQ feedback disabling process for each HARQ process in an uplink. In the example of Fig. 12, HARQ feedback is enabled for HARQ process #1, and HARQ feedback is disabled for HARQ process #2.

[0146] As shown in FIG. 12, first, a control unit (e.g., control unit 23) of a base station device (e.g., base station 20, base station 30) sends a notification to disable a specific HARQ process via wireless communication (e.g., wireless communication unit 21) in the same manner as in step S301 above (step S401).

[0147] Next, a control unit (eg, control unit 23) of a base station device (eg, base station 20, base station 30) performs DCI transmission (HARQ process #1) via wireless communication (eg, wireless communication unit 21) (step S402).

[0148] The control unit 55 of the terminal device 50 that has received the DCI transmission performs PUSCH data transmission (HARQ process #1) via the wireless communication unit 51 (step S403). The control unit 55 of the terminal device 50 holds the transmitted PUSCH data in the HARQ buffer 522a of the HARQ process #1 in the storage unit 52 (step S405).

[0149] A control unit (e.g., the control unit 23) of a base station device (e.g., the base station 20, the base station 30) that has received the PUSCH data transmission (HARQ process #1) from the terminal device 50 decodes the PUSCH data. Here, it is assumed that the decoding of the PUSCH data in the HARQ process #1 has failed (step S404).

[0150] Due to failure in decoding of the PUSCH data in HARQ process #1, a control unit (e.g., control unit 23) of a base station device (e.g., base station 20, base station 30) stores the unsuccessfully decoded PUSCH data in the HARQ buffer of HARQ process #1 in a memory unit (e.g., memory unit 22) (step S406).

[0151] Next, a control unit (eg, control unit 23) of a base station device (eg, base station 20, base station 30) performs DCI transmission (HARQ process #2) via wireless communication (eg, wireless communication unit 21) (step S407).

[0152] The control unit 55 of the terminal device 50 that has received the DCI transmission performs PUSCH data transmission (HARQ process #2) via the wireless communication unit 51 (step S408). For the HARQ process #2, retransmission processing is disabled in the prior notification (step S401). Therefore, the control unit 55 of the terminal device 50 does not hold the transmitted PUSCH data in the HARQ buffer of the HARQ process #2 in the storage unit 52 (step S411).

[0153] A control unit (e.g., the control unit 23) of a base station device (e.g., the base station 20, the base station 30) that has received the PUSCH data transmission (HARQ process #2) from the terminal device 50 decodes the PUSCH data. Here, it is assumed that the decoding of the PUSCH data in the HARQ process #2 has failed (step S409).

[0154] In this HARQ process #2, retransmission processing is disabled (HARQ feedback disabling). Therefore, a control unit (e.g., control unit 23) of a base station device (e.g., base station 20, base station 30) does not hold the received PUSCH data in the HARQ buffer of HARQ process #2 in a storage unit (e.g., storage unit 22) (step S410).

[0155] Next, a control unit (eg, control unit 23) of a base station device (eg, base station 20, base station 30) transmits DCI (a retransmission request for HARQ process #1) via wireless communication (eg, wireless communication unit 21) (step S412).

[0156] The control unit 55 of the terminal device 50 that has received the DCI transmission (retransmission request for HARQ process #1) performs PUSCH data transmission (retransmission of HARQ process #1) via the wireless communication unit 51 (step S413).

[0157] A control unit (e.g., control unit 23) of a base station device (e.g., base station 20, base station 30) that receives the retransmitted PUSCH data decodes the PUSCH data by soft combining the data stored in the HARQ buffer of HARQ process #1 with the retransmitted data (step S414). Here, it is assumed that the decoding of the PUSCH data is successful (step S415).

[0158] When the PUSCH data is successfully decoded, a control unit (e.g., control unit 23) of the base station device (e.g., base station 20, base station 30) clears the data in the HARQ buffer of HARQ process #1 in the storage unit (e.g., storage unit 22) (step S416). Since there is no DCI transmission (a retransmission request for HARQ process #1) from the base station device, the control unit 55 of the terminal device 50 clears the data in the HARQ buffer 522a of HARQ process #1 (step S417).

[0159] <2-12.Characteristic compensation for HARQ disabling> When HARQ feedback is disabled, retransmission is not possible even if a decoding error occurs, so it is important to reduce the decoding error at the time of the first transmission. Therefore, the control unit (e.g., control unit 23) of the base station device (e.g., base station 20, base station 30) and the control unit 55 of the terminal device 50 use the following techniques (A) to (C) to reduce the decoding error. (A) Extend CQI while introducing HARQ feedback disabling (B) At the same time as disabling HARQ feedback, switch the MCS table to a low spectral efficiency table. (C) When HARQ feedback disabling is enabled, switch to repetition transmission of the same Transport Block (TB).

[0160] An example of the method (A) is as follows: In an HARQ process in which HARQ feedback disabling is enabled, the CQI is determined based on the extended CQI, and in an HARQ process in which HARQ feedback disabling is disabled, the CQI is determined based on the conventional CQI.

[0161] A base station device (e.g., base station 20, base station 30) needs to know two types of CQI: CQI for HARQ enabling (or conventional CQI) and CQI for HARQ disabling. Therefore, as (a), the terminal device 50 returns one type of reference CQI (e.g., for enabling, long term CQI, etc.). A control unit (control unit 23) of the base station device (e.g., base station 20, base station 30) estimates one CQI (e.g., for disabling) from the other CQI (e.g., for enabling) and determines the MCS. Note that information that assists the estimation (e.g., two types of inter-QCI offset values) may be reported in advance from the terminal device 50 to the base station device.

[0162] As for (b), the terminal device 50 returns two types of CQI (for both enabling and disabling). The base station device (for example, the base station 20 or 30) determines the MCS based on the CQI. Then, the terminal device 50 feeds back the two types of CQI indexes.

[0163] Furthermore, when defining both a CQI for HARQ enabling and a CQI for HARQ disabling, the target BLER is also defined for both, for example, Target BLER=0.1 for CQI for HARQ enabling and Target BLER=0.00001 for CQI for HARQ disabling.

[0164] The CQI table is as follows. When defining both CQI for HARQ feedback enabling and CQI for HARQ feedback disabling, it is necessary to define both CQI tables. Add a CQI table that supports new Target BLER. It may be calculated based on an existing CQI table. For example, the code rate in the existing table is multiplied by a coefficient less than 1 to use the code rate. ·You may use a value that is one step lower than the Modulation in the existing table. For example, 256QAM → 64QAM, 64QAM → 16QAM, 16QAM → QPSK, QPSK → BPSK. In the case of QPSK, keep it as QPSK.

[0165] The CQI calculation method is as follows. The CSI reference resource is assumed to be as follows: 1) Repeat the test a specified number of times. 2) If Repetition is multiple, set Redundancy version to [0,0,0,0] or [0,2,3,1] or [0,3,0,3]. 3) The calculation method is switched by enabling or disabling the HARQ process. For example, the calculation method of the CSI reference resource is changed for each HARQ process. 4) Add a CQI offset. For example, if CQI offset=1 and the CQI calculation result is CQI=8, report CQI=7.

[0166] An example of the method (B) is as follows: In an HARQ process with HARQ feedback disabling enabled, the MCS table is determined based on an MCS table with lower spectral efficiency compared to other MCS tables. Also, in an HARQ process with HARQ feedback disabling disabled, the MCS table is determined based on an MCS table with higher spectral efficiency compared to other MCS tables.

[0167] In addition, when defining both the MCS for HARQ feedback enabling and the MCS for HARQ feedback disabling, both MCS tables are defined. For example, the MCS table for HARQ feedback enabling uses the existing MCS table 1 or 2, and the MCS table for HARQ feedback disabling uses the existing MCS table 3.

[0168] Alternatively, the calculation may be performed based on an existing MCS table. For example, a code rate obtained by multiplying the code rate in the existing table by a coefficient less than 1 may be used.

[0169] Also, the modulation in the existing table may be lowered by one step. For example, 256QAM → 64QAM, 64QAM → 16QAM, 16QAM → QPSK, QPSK → BPSK. In the case of QPSK, it remains QPSK.

[0170] Furthermore, when defining both the MCS for HARQ enabling and the MCS for HARQ disabling, the target BLER is defined for both, for example, Target BLER=0.1 for CQI for HARQ enabling and Target BLER=0.00001 for CQI for HARQ disabling.

[0171] The method (C) is, for example, as follows. Repetition transmission may be performed with the same Redundancy Version (RV) or with different RVs. In an HARQ process with HARQ feedback disabling enabled, repetition transmission of the same TB may be performed, and in an HARQ process with HARQ feedback disabling disabled, a single TB may be transmitted. In an HARQ process with HARQ feedback disabling enabled, the number of repetition transmissions of the same TB may be increased, and in an HARQ process with HARQ feedback disabling disabled, the number of repetition transmissions of the same TB may be transmitted without increasing the number of repetition transmissions.

[0172] <3-1. Modifications when the number of HARQ processes can be increased> Next, a modified example in which the number of HARQ processes in the terminal device 50 can be increased (including HARQ feedback enabling after HARQ feedback disabling) will be described.

[0173] A terminal device 50 that can increase the number of HARQ processes and the buffer size related to the HARQ buffer transmits capability information (UE radio access capability) to a non-terrestrial network (for example, a base station device) under the control of a control unit 55. The capability information may be transmitted in response to an Enquiry issued by the RAN (satellite) immediately after RRC Connected, or may be transmitted at the time of RRC Setup Complete.

[0174] Here, the capability information includes the following information: Information on whether the number of HARQ processes can be increased Information on whether the buffer size can be increased - Maximum supported size of HARQ process -Maximum supported buffer size information

[0175] When the number of HARQ processes is increased or decreased, the control unit 55 of the terminal device 50 notifies information on increasing or decreasing the number of HARQ processes, or switching to return to the default value. This notification can be an explicit notification or an implicit notification.

[0176] Explicit notification includes, for example, notification in system information, RRC signaling, or MAC CE, or notification in DCI or UCI. This explicit notification may include information notifying the maximum number of switches. When HO is performed from a TN to an NTN, the information may be included in the HO command (RRCReconfiguration including ReconfigurationWithSync).

[0177] In the implicit notification, the terminal device 50 determines whether to disable HARQ feedback based on system information or other information notified by RRC signaling. For example, in the implicit notification, the terminal device 50 may determine disabling based on the following information in the system information, etc. Location information of the base station device and the terminal device 50 Propagation distance and propagation delay information between the base station device and the terminal device 50 Altitude of the base station device and the terminal device 50 The moving speed of the base station device and the terminal device 50 Timing advance information

[0178] For example, the control unit 55 of the terminal device 50 may increase the number of HARQ processes when the Timing advance is greater than a predetermined value, or may decrease the number of HARQ processes or return it to a default value when the Timing advance is less than a predetermined value.

[0179] Furthermore, the control unit 55 of the terminal device 50 may determine the number of HARQ processes based on information about power control. For example, if power control is greater than a predetermined value, the control unit 55 may increase the number of HARQ processes. If power control is less than a predetermined value, the control unit 55 may decrease the number of HARQ processes or return the number to a default value.

[0180] Furthermore, the control unit 55 of the terminal device 50 may notify the number of HARQ processes. This notification may be an explicit notification or an implicit notification.

[0181] Explicit notification can be, for example, notification in system information, RRC signaling, or MAC CE. This notification can be done by notifying the absolute value of the number of HARQ processes, or by switching the number of HARQ processes among multiple patterns (e.g., switching among four patterns of 16, 32, 48, and 64).

[0182] Also, explicit notification can be performed by DCI or UCI. In this DCI or UCI notification, a field for notifying the number of HARQ processes is added.

[0183] In addition, when performing HO from a TN to an NTN, the notification may be included in the HO command (RRCReconfiguration including ReconfigurationWithSync).

[0184] In the implicit notification, the terminal device 50 determines whether to disable HARQ feedback based on system information or other information notified by RRC signaling. For example, in the implicit notification, the terminal device 50 may determine disabling based on the following information in the system information, etc. Location information of the base station device and the terminal device 50 Propagation distance and propagation delay information between the base station device and the terminal device 50 Altitude of the base station device and the terminal device 50 The moving speed of the base station device and the terminal device 50 Timing advance information

[0185] For example, the control unit 55 of the terminal device 50 determines the number of HARQ processes according to the value of Timing advance. Also, the control unit 55 of the terminal device 50 may determine the number of HARQ processes according to the value of Power control. Also, the control unit 55 of the terminal device 50 may notify (CORESET, search space, scrambling (DMRS, RNTI)) by other physical information of the PDCCH.

[0186] In addition, the control unit (e.g., control unit 23) of the base station device (e.g., base station 20, base station 30) and the control unit 55 of the terminal device 50 can notify the HARQ process identifier after increasing or decreasing the number of HARQ processes as follows.

[0187] (A) Explicit notification of HARQ process identifier Increase the number of bits in the notification field in the DCI HARQ process. - Notify HARQ process identifier via UCI.

[0188] (B) When the HARQ process identifier is implicitly notified -Notified by other physical information of PDCCH (CORESET, search space, scrambling (DMRS, RNTI)). If DCI is notified in CORESET #A, the HARQ process identifier should be read as #0~15. If DCI is notified in CORESET #B, the HARQ process identifier should be read as #(0~15)+16. · The slot number (or SFN) changes the interpretation of the HARQ process identifier notified by the DCI.

[0189] For example, if DCI is notified in slot #0, the HARQ process identifier shall be read as #0 to 15, and if DCI is notified in slot #1, the HARQ process identifier shall be read as #(0 to 15)+16. Also, if DCI is notified in an even-numbered slot, the HARQ process identifier shall be read as #0 to 15, and if DCI is notified in an odd-numbered slot, the HARQ process identifier shall be read as #(0 to 15)+16. Note that the even and odd numbers may be reversed.

[0190] ·Notified by the reference signal sequence / port. For example, switching is performed based on the DMRS sequence initialization notified by DCI. If DMRS sequence initialization is 0, the HARQ process identifier is interpreted as #0~15, and if DMRS sequence initialization is 1, the HARQ process identifier is interpreted as #(0~15)+16. Switching may also be performed based on the antenna port. For example, when transmitting and receiving using antenna port #0, the HARQ process identifier is interpreted as #0~15, and when transmitting and receiving using antenna port #1, the HARQ process identifier is interpreted as #(0~15)+16.

[0191] In addition, the DRX operation when the number of HARQ processes is increased (including an increase (restoration) of the number of HARQ processes available for feedback by HARQ feedback enabling) or decreased (including a decrease in the number of HARQ processes available for feedback by HARQ feedback disabling) is as follows.

[0192] For example, the HARQRTTTimer (drx-HARQ-RTT-TimerDL, drx-HARQ-RTT-TimerUL) and drx-RetransmissionTimer (drx-RetransmissionTimerDL, drx-RetransmissionTimerUL) used in NTN communication may be set by the RAN to values ​​different from the HARQRTTTimer (drx-HARQ-RTT-TimerDL, drx-HARQ-RTT-TimerUL) and drx-RetransmissionTimer (drx-RetransmissionTimerDL, drx, drx-RetransmissionTimer (drx-RetransmissionTimerDL, drx-RetransmissionTimerUL) used in TN communication.

[0193] One HARQRTTTimer and one drx-RetransmissionTimer are associated with one HARQ process. Therefore, for example, if the number of HARQ processes used in NTN communication is greater than the number of HARQ processes used in TN communication, the frequency of start / stop of the HARQRTTTimer and drx-RetransmissionTimer may also be high. If the frequency of start of the drx-RetransmissionTimer increases, the frequency and time of PDCCH monitoring (e.g., Active Time) will also increase, which may be inconvenient from the viewpoint of UE power saving.

[0194] Therefore, when the number of HARQ processes used in NTN communication is greater than the number of HARQ processes used in TN communication, at least the value of the drx-RetransmissionTimer used in NTN communication may be set shorter than the value of the drx-RetransmissionTimer used in TN communication. As a result, even if the number of HARQ processes is greater than the number of HARQ processes, the total running period of the drx-RetransmissionTimer that the UE should monitor the PDCCH in NTN communication is shorter than the simple product of the number of running HARQ processes in NTN communication and the value of the drx-RetransmissionTimer used in TN communication, so that the effect of this embodiment can be achieved while maintaining UE power saving.

[0195] In addition, in NTN communication, the difference between the timing when a transmission signal transmitted from a transmitter should reach a receiver and the timing when the signal is actually received may be larger than in TN communication. Also, the RTT between a base station (RAN) and a mobile station (UE) in NTN communication may be larger than the RTT in TN communication. This may be due to the length of the distance between the base station (RAN) and the mobile station (UE). Therefore, in order to absorb the difference, the values ​​of HARQRTTTimer and drx-RetransmissionTimer for NTN communication may be set to values ​​larger than the values ​​of HARQRTTTimer and drx-RetransmissionTimer for TN communication.

[0196] The values ​​of HARQRTTTimer and drx-RetransmissionTimer used in NTN communication may be set separately from the values ​​of HARQRTTTimer and drx-RetransmissionTimer used in TN communication (for example, included in DRX-Config) and transmitted from the RAN to the UE, or may be pre-set in the UE as default-DRX-Config for NTN communication.

[0197] When a UE is RRC Connected with a TN communication base station and can communicate with an NTN communication base station (for example, when Dual Connectivity is configured with the TN communication base station as the MN and the NTN communication base station as the SN, or when the TN communication base station is used as the anchor carrier to perform NTN communication with an NTN communication base station), both the values ​​of HARQRTTTimer and drx-RetransmissionTimer used in NTN communication and the values ​​of HARQRTTTimer and drx-RetransmissionTimer used in TN communication may be included in a single RRCReconfiguration and transmitted.

[0198] In addition, the above-mentioned HARQRTTTimer and drx-RetransmissionTimer may be timers for DL ​​(e.g., drx-HARQ-RTT-TimerDL and drx-RetransmissionTimerDL), or timers for UL (e.g., drx-HARQ-RTT-TimerUL and drx-RetransmissionTimerUL), or both.

[0199] Furthermore, the above-mentioned HARQRTTTimer and drx-RetransmissionTimer may have values ​​set in units of subframes or in units of symbols. Furthermore, the above-mentioned HARQRTTTimer and drx-RetransmissionTimer may have values ​​set in units of PDCCH periods (pp). When the values ​​of HARQRTTTimer and drx-RetransmissionTimer are set in units of PDCCH periods (pp), the values ​​of HARQRTTTimer and drx-RetransmissionTimer that should actually be used by the UE may be derived by multiplying them by a value corresponding to the coverage level of the UE itself (an index based on radio quality, for example, a coverage enhancement level). The value corresponding to the coverage level of the UE itself may be transmitted from the RAN to the UE by RRC signaling (for example, RRCReconfiguration).

[0200] <3-2. Other modifications> For example, in 3GPP Rel.15, the transmission timing of HARQ Feedback (ACK / NACK) is specified as follows: In the case of DCI format 1_0, the DCI includes a PDSCH-to-HARQ-timing-indicator field, whose values ​​are mapped to {1,2,3,4,5,6,7,8}. When the UE finishes receiving a PDSCH (SPS (Semi-Persistent Scheduling) PDSCH) in slot n, the UE transmits a PUCCH (i.e., HARQ Feedback (ACK / NACK)) in slot n+k. Here, k is provided by the PDSCH-to-HARQ-timing-indicator field of DCI format 1_0. In the case of DCI format 1_1, the PDSCH-to-HARQ-timing-indicator field (0, 1, 2, or 3 bits) included in the DCI is mapped to the number of slots of PUCCH to transmit HARQ feedback, and indicates which of the values ​​provided by the RRC parameter dl-DataToUL-ACK should be referenced. That is, the UE transmits PUCCH (i.e., HARQ Feedback (ACK / NACK)) in slot n+k using the value of dl-DataToUL-ACK corresponding to the bit combination indicated by the PDSCH-to-HARQ-timing-indicator field in DCI format 1_1 as k. Note that dl-DataToUL-ACK may be transmitted from the RAN to the UE by the above-mentioned semi-static notification.

[0201] The relationship between the PDSCH-to-HARQ-timing-indicator field in the case of DCI format 1_1 and the value of dl-DataToUL-ACK to be used is as shown in Table 1 below. [Table 1]

[0202] If the timing for dynamically disabling / enabling HARQ feedback (any of the above conditions (a-1, a-2, b-1, b-2)) is earlier than slot n+k in which the PUCCH (i.e., HARQ Feedback (ACK / NACK)) indicated by the PDSCH-to-HARQ-timing-indicator field included in the DCI should be transmitted, the UE (terminal device 50) may ignore the value of the PDSCH-to-HARQ-timing-indicator field. In other words, it is not necessary to perform HARQ feedback. More specifically, if the subframe n+k or slot n+k indicated by the above-mentioned condition (a-2) is earlier than the slot n+k in which the PUCCH (ie, HARQ Feedback (ACK / NACK)) indicated by the PDSCH-to-HARQ-timing-indicator field included in the DCI should be transmitted, the UE (terminal device 50) may ignore the value of the PDSCH-to-HARQ-timing-indicator field. In other words, if the subframe n+k or slot n+k indicated by the above-mentioned condition (a-2) is earlier than the slot n+k in which the PUCCH (ie, HARQ Feedback (ACK / NACK)) indicated by the PDSCH-to-HARQ-timing-indicator field included in the DCI should be transmitted, the UE (terminal device 50) is not expected to transmit the PUCCH (ie, HARQ Feedback (ACK / NACK)) in the slot n+k derived from the PDSCH-to-HARQ-timing-indicator field. In this case, the notification indicating the timing (eg, n+k) for HARQ feedback disabling and the PDSCH-to-HARQ-timing-indicator field may be included in the same DCI or in different DCIs.

[0203] Furthermore, in the embodiments of the present disclosure, the target of enabling / disabling has been described as HARQ feedback, but the target of enabling / disabling may be the HARQ process itself, or a process within the HARQ process other than HARQ feedback.

[0204] The above-mentioned Enabling / Disabling may be replaced with the expressions Activation / Deactivation. In addition, the management device 10, the base stations 20, 30, 40, or the control device that controls the terminal device 50 of the present embodiment may be realized by a dedicated computer system or a general-purpose computer system.

[0205] For example, a communication program for executing the above-mentioned operations (e.g., initial connection processing, HARQ processing, etc.) is stored in a computer-readable recording medium such as an optical disk, a semiconductor memory, a magnetic tape, a flexible disk, etc. and distributed. Then, for example, the program is installed in a computer and the above-mentioned processing is executed to configure a control device. In this case, the control device may be a device (e.g., a personal computer) external to the management device 10, the base station 20, 30, 40, or the terminal device 50. Also, the control device may be a device (e.g., the control unit 13, the control unit 23, or the control unit 55) internal to the base station 20, 30, 40, or the terminal device 50.

[0206] The communication program may be stored in a disk device provided in a server device on a network such as the Internet, and may be downloaded to a computer. The above-mentioned functions may be realized by cooperation between an OS (Operating System) and application software. In this case, the parts other than the OS may be stored on a medium and distributed, or the parts other than the OS may be stored in a server device and may be downloaded to a computer.

[0207] Furthermore, among the processes described in the above embodiments, all or part of the processes described as being performed automatically can be performed manually, or all or part of the processes described as being performed manually can be performed automatically by a known method. In addition, the information including the processing procedures, specific names, various data and parameters shown in the above documents and drawings can be changed arbitrarily unless otherwise specified. For example, the various information shown in each drawing is not limited to the illustrated information.

[0208] In addition, each component of each device shown in the figure is a functional concept, and does not necessarily have to be physically configured as shown in the figure. In other words, the specific form of distribution and integration of each device is not limited to that shown in the figure, and all or part of them can be functionally or physically distributed and integrated in any unit according to various loads, usage conditions, etc.

[0209] In addition, the above-described embodiments can be combined as appropriate in the areas where the processing contents are not contradictory. In addition, the order of the steps shown in the flowcharts or sequence diagrams of the above-described embodiments can be changed as appropriate.

[0210] <4. Conclusion> As described above, according to one embodiment of the present disclosure, the terminal device 50 can disable feedback for retransmission (HARQ feedback disabling) upon receiving a notification to disable feedback for retransmission in HARQ. This can contribute to resolving the shortage of the number of HARQ processes and to suppressing deterioration of communication quality.

[0211] Although the embodiments of the present disclosure have been described above, the technical scope of the present disclosure is not limited to the above-described embodiments as they are, and various modifications are possible without departing from the gist of the present disclosure. In addition, components of different embodiments and modifications may be appropriately combined.

[0212] Furthermore, the effects of each embodiment described in this specification are merely examples and are not limiting, and other effects may also be provided.

[0213] The present technology can also be configured as follows. (1) A terminal device, A communication unit and a control unit are included. The control unit is receiving, via the communication unit, invalid information of a hybrid automatic repeat reQuest (HARQ) feedback; The one or more HARQ feedbacks indicated by the invalid information of the HARQ feedback are recognized as invalid; The invalid information of the HARQ feedback is set for each cell, each beam, each component carrier, each BWP (BandWidth Part), each UE (User Equipment), or each HARQ process. A terminal device comprising: (2) The invalid information of the HARQ feedback is sent by a semi-static notification, a dynamic notification, or a combination of the semi-static notification and the dynamic notification from a base station device. The terminal device according to (1) above. (3) The semi-static notification is a signal notification of RRC (Radio Resource Control). The terminal device according to (2) above. (4) The dynamic notification is a notification of DCI (Downlink Control Information) or UCI (Uplink Control Information). The terminal device according to (2) or (3) above. (5) The invalid information of the HARQ feedback includes the number of invalid HARQ processes in one or more HARQ processes; A terminal device according to any one of (1) to (4). (6) The invalid information of the HARQ feedback includes identification information of an invalid HARQ process among one or more HARQ processes. A terminal device according to any one of (1) to (5). (7) the control unit switches compensation for error rate characteristics in response to switching from a HARQ process in which retransmission is not disabled to a HARQ process in which retransmission is disabled based on the disabled information of the HARQ feedback. A terminal device according to any one of (1) to (6). (8) The control unit, in response to switching to the HARQ process in which the retransmission is disabled, reduces compensation of the error rate characteristic compared to a case in which the HARQ process in which the retransmission is not disabled. The terminal device according to (7) above. (9) The control unit transmits information on the increase or decrease in the number of the one or more HARQ processes via the communication unit in response to the increase or decrease. A terminal device according to any one of (1) to (8). (10) A base station device, A communication unit and a control unit are included. The control unit is Transmitting invalid information of HARQ (Hybrid Automatic Repeat reQuest) feedback via the communication unit; The one or more HARQ processes indicated by the invalid information of the HARQ feedback are recognized as invalid; The invalid information of the HARQ feedback is set for each cell, each beam, each component carrier, each BWP (BandWidth Part), each UE (User Equipment), or each HARQ process. A base station device comprising: (11) The control unit transmits the invalid information of the HARQ feedback by any one of semi-static notification, dynamic notification, and a combination of the semi-static notification and the dynamic notification. The base station device according to claim 10. (12) The semi-static notification is a signal notification of RRC (Radio Resource Control). The base station device according to (11) above. (13) The dynamic notification is a notification of DCI (Downlink Control Information) or UCI (Uplink Control Information). The base station device according to (11) or (12), (14) The invalid information of the HARQ feedback includes the number of invalid HARQ processes in one or more HARQ processes; The base station device according to any one of (10) to (13). (15) The invalid information of the HARQ feedback includes identification information of an invalid HARQ process among one or more HARQ processes. The base station device according to any one of (10) to (14). (16) the control unit switches compensation for error rate characteristics in response to switching from a HARQ process in which retransmission is not disabled to a HARQ process in which retransmission is disabled based on the disabled information of the HARQ feedback. The base station device according to any one of (10) to (15). (17) The control unit, in response to switching to the HARQ process in which the retransmission is disabled, reduces compensation of the error rate characteristic compared to a case in which the HARQ process in which the retransmission is not disabled. The base station device according to claim 16. (18) A method for controlling a terminal device, comprising: receiving, via a communication unit, invalid information of a hybrid automatic repeat reQuest (HARQ) feedback; The one or more HARQ processes indicated by the invalid information of the HARQ feedback are recognized as invalid; The invalid information of the HARQ feedback is set for each cell, each beam, each component carrier, each BWP (BandWidth Part), each UE (User Equipment), or each HARQ process; A method for controlling a terminal device, comprising: (19) A method for controlling a base station device, comprising: Transmitting HARQ (Hybrid Automatic Repeat reQuest) feedback invalid information via a communication unit; The one or more HARQ processes indicated by the invalid information of the HARQ feedback are recognized as invalid; The invalid information of the HARQ feedback is set for each cell, each beam, each component carrier, each BWP (BandWidth Part), each UE (User Equipment), or each HARQ process; A method for controlling a base station device, comprising: [Explanation of symbols]

[0214] 1. Communication systems 10…Management device 11…Communications Department 12, 22, 52...Storage section 13, 23, 55…Control section 20, 30, 40…base station 21, 51…Radio communication section 50...Terminal device 53…Network communication section 54…Input / output section 211...Reception processing unit 211a, 511a...Radio receiving unit 211b, 511b...demultiplexer 211c, 511c…Demodulation section 211d, 511d…Decoding section 212...Transmission processing unit 212a, 512a...encoding section 212b, 512b...Modulation section 212c, 512c...Multiplex section 212d, 512d...Radio transmitter 213, 513…Antenna 521, 522, 523…Storage area 521a, 522a, 523a…HARQ buffer ABP1…Airborne Platform C2…Cell CN: Core network D1…radius PN: Public network R1…Angle RAN: Radio Access Network SBP1, SBP2...Spaceborne Platform TN1, TN2...Terrestrial networks

Claims

1. A terminal device, A communication unit and a control unit are included. The control unit is receiving, via the communication unit, invalid information of HARQ (Hybrid Automatic Repeat reQuest) feedback transmitted by a semi-static notification, a dynamic notification, or a combination of the semi-static notification and the dynamic notification from a base station device; The one or more HARQ feedbacks indicated by the invalid information of the HARQ feedback are recognized as invalid; The semi-static notification is a signal notification of RRC (Radio Resource Control), The invalid information of the HARQ feedback is set for each cell, each beam, each component carrier, each BWP (BandWidth Part), each UE (User Equipment), or each HARQ process, The invalid information of the HARQ feedback includes identification information of an invalid HARQ process among one or more HARQ processes, and indicates the start of a HARQ-RTT-Timer when one or more HARQ feedbacks indicated by the invalid information of the HARQ feedback are valid; A terminal device comprising:

2. The dynamic notification is a notification of DCI (Downlink Control Information) or UCI (Uplink Control Information), 2. The terminal device according to claim 1 .

3. The invalid information of the HARQ feedback includes the number of invalid HARQ processes in one or more HARQ processes; 2. The terminal device according to claim 1 .

4. the control unit switches compensation for error rate characteristics in response to switching from a HARQ process in which retransmission is not disabled to a HARQ process in which retransmission is disabled based on the disabled information of the HARQ feedback.

2. The terminal device according to claim 1 .

5. The control unit, in response to switching to the HARQ process in which the retransmission is disabled, increases compensation of the error rate characteristic compared to a case in which the HARQ process in which the retransmission is not disabled.

5. The terminal device according to claim 4.

6. The control unit transmits information on the increase or decrease in the number of the one or more HARQ processes via the communication unit in response to the increase or decrease.

2. The terminal device according to claim 1 .

7. A base station device, A communication unit and a control unit are included. The control unit is Transmitting, via the communication unit, invalid information of HARQ (Hybrid Automatic Repeat reQuest) feedback, which is sent by any one of a semi-static notification, a dynamic notification, or a combination of the semi-static notification and the dynamic notification; The one or more HARQ processes indicated by the invalid information of the HARQ feedback are recognized as invalid, The semi-static notification is a signal notification of RRC (Radio Resource Control), The invalid information of the HARQ feedback is set for each cell, each beam, each component carrier, each BWP (BandWidth Part), each UE (User Equipment), or each HARQ process, The invalid information of the HARQ feedback includes identification information of an invalid HARQ process among one or more HARQ processes, and indicates the start of a HARQ-RTT-Timer when one or more HARQ feedbacks indicated by the invalid information of the HARQ feedback are valid; A base station device comprising:

8. The dynamic notification is a notification of DCI (Downlink Control Information) or UCI (Uplink Control Information), The base station device according to claim 7 .

9. The invalid information of the HARQ feedback includes the number of invalid HARQ processes in one or more HARQ processes; The base station device according to claim 7 .

10. the control unit switches compensation for error rate characteristics in response to switching from a HARQ process in which retransmission is not disabled to a HARQ process in which retransmission is disabled based on the disabled information of the HARQ feedback. The base station device according to claim 7 .

11. The control unit, in response to switching to the HARQ process in which the retransmission is disabled, increases compensation of the error rate characteristic compared to a case in which the HARQ process in which the retransmission is not disabled. The base station device according to claim 10 .

12. A method for controlling a terminal device, comprising: receiving, via a communication unit, invalid information of HARQ (Hybrid Automatic Repeat reQuest) feedback transmitted by a semi-static notification, a dynamic notification, or a combination of the semi-static notification and the dynamic notification from a base station device; The one or more HARQ feedbacks indicated by the invalid information of the HARQ feedback are recognized as invalid; The semi-static notification is a signal notification of RRC (Radio Resource Control), The invalid information of the HARQ feedback is set for each cell, each beam, each component carrier, each BWP (BandWidth Part), each UE (User Equipment), or each HARQ process, The invalid information of the HARQ feedback includes identification information of an invalid HARQ process among one or more HARQ processes, and indicates the start of a HARQ-RTT-Timer when one or more HARQ feedbacks indicated by the invalid information of the HARQ feedback are valid; A method for controlling a terminal device, comprising:

13. A method for controlling a base station device, comprising: Transmitting, via a communication unit, invalid information of HARQ (Hybrid Automatic Repeat reQuest) feedback, which is sent by any one of a semi-static notification, a dynamic notification, or a combination of the semi-static notification and the dynamic notification; The one or more HARQ processes indicated by the invalid information of the HARQ feedback are recognized as invalid, The semi-static notification is a signal notification of RRC (Radio Resource Control), The invalid information of the HARQ feedback is set for each cell, each beam, each component carrier, each BWP (BandWidth Part), each UE (User Equipment), or each HARQ process, The invalid information of the HARQ feedback includes identification information of an invalid HARQ process among one or more HARQ processes, and indicates the start of a HARQ-RTT-Timer when one or more HARQ feedbacks indicated by the invalid information of the HARQ feedback are valid; A method for controlling a base station device, comprising:

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