Terminal, base station and communication method

Abstract

The present invention is used for appropriately controlling communication timing. The terminal comprises a receiving circuit. Receiving a first stop timing for downlink communication in the first communication path before switching and a second stop timing for uplink communication in the first communication path; control information related to at least one of a first start timing of downlink communication in the switched second communication path and a second start timing of uplink communication in the second communication path; and a control circuit that controls a resynchronization process in the second communication path based on the control information.

Description

Technical Field

[0001] This disclosure relates to terminals, base stations, and communication methods. Background Technology

[0002] Regarding 5G standardization, New Radio access technology (NR) has been standardized by 3GPP (3rd Generation Partnership Project) and the NR Release 15 (Rel.15) specification has been released.

[0003] Existing technical documents

[0004] Non-patent literature

[0005] Non-patent literature 1: 3GPP, TR 38.821, V16.2.0 “Solutions for NR to support non-terrestrial networks (NTN) (Release 16)”

[0006] Non-Patent Literature 2: R2-2305937, “Satellite switching without PCI change”, InterDigital Summary of the Invention

[0007] However, there is still room for research on control methods for communication timing.

[0008] The non-limiting embodiments of this disclosure help to provide terminals, base stations, and communication methods capable of appropriately controlling communication timing.

[0009] A terminal according to an embodiment of this disclosure includes: a receiving circuit that receives control information relating to at least one of a first stop timing of downlink communication in a first communication path before switching, a second stop timing of uplink communication in the first communication path, a first start timing of downlink communication in a second communication path after switching, and a second start timing of uplink communication in the second communication path; and a control circuit that controls resynchronization processing in the second communication path based on the control information.

[0010] It should be noted that these general or specific methods can be implemented by systems, devices, methods, integrated circuits, computer programs or recording media, or by any combination of systems, devices, methods, integrated circuits, computer programs and recording media.

[0011] According to one embodiment of this disclosure, communication timing can be appropriately controlled.

[0012] Further advantages and effects of one aspect of this disclosure will be illustrated by the description and accompanying drawings. These advantages and / or effects are provided by the various embodiments and the features described in the description and drawings, but not necessarily all of them need to be provided in order to obtain one or more of the same features. Attached Figure Description

[0013] Figure 1 This is a diagram illustrating an example of satellite handover.

[0014] Figure 2 This is a block diagram representing a structural example of a part of a base station.

[0015] Figure 3 This is a block diagram representing a structural example of a part of a terminal.

[0016] Figure 4 This is a block diagram illustrating an example of the structure of a base station.

[0017] Figure 5 This is a block diagram representing an example of the structure of a terminal.

[0018] Figure 6 This is a timing diagram representing the actions of the base station and the terminal.

[0019] Figure 7 This is a timing diagram representing the actions of the base station and the terminal.

[0020] Figure 8 This is a timing diagram representing the actions of the base station and the terminal.

[0021] Figure 9 This is a timing diagram representing the actions of the base station and the terminal.

[0022] Figure 10 This is a timing diagram representing the actions of the base station and the terminal.

[0023] Figure 11 This is a timing diagram representing the actions of the base station and the terminal.

[0024] Figure 12 This is a timing diagram representing the actions of the base station and the terminal.

[0025] Figure 13 This is a diagram illustrating the architecture of a 3GPP NR (3rd generation partnership project new radio) system.

[0026] Figure 14This is a schematic diagram illustrating the functional separation between NG-RAN (Next Generation-Radio Access Network) and 5GC (5th Generation Core).

[0027] Figure 15 This is a sequence diagram of the setup / resetting process for Radio Resource Control (RRC) connections.

[0028] Figure 16 This is a schematic diagram illustrating the application scenarios of high-capacity high-speed communication (eMBB: enhanced mobile broadband), massive machine-type communications (mMTC: massive machine-type communications), and ultra-reliable and low-latency communications (URLLC: ultra-reliable and low-latency communications).

[0029] Figure 17 This is a block diagram representing an exemplary 5G system architecture for non-roaming scenarios. Detailed Implementation

[0030] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings.

[0031] [About Non-Terrestrial Networks (NTN)]

[0032] NR Rel.15 has been standardized as a wireless access technology for terrestrial networks. On the other hand, in Rel. 17, non-terrestrial networks (NTNs) such as communications using satellites or high-altitude platform stations (HAPS) are supported (e.g., Non-Patent Document 1). In Rel. 18, extended technologies for NTNs are being investigated.

[0033] One of the extended technologies for NTN is mobility enhancement technologies such as handover and cell reselection. For example, for non-geostationary satellites such as Low Earth Orbit (LEO) satellites, research is underway to improve the efficiency of satellite or feeder link handover. Furthermore, a feeder link is a wireless link between a ground base station or gateway (GW) and a satellite.

[0034] For example, such as Figure 1 As shown, a handover method is being investigated that changes the communication path to the terminal via the satellite or feeder link without altering the cell ID (e.g., Physical Cell Identification (PCI)) during satellite or feeder link handover (e.g., Non-Patent Document 2). In this method, since there is no need for similar handover processes such as radio resource control (RRC) connection re-establishment or security updates (e.g., Layer 3 mobility processing), satellite or feeder link handover can be achieved through simple processing.

[0035] Here, during the handover of a satellite or feeder link used for communication (hereinafter referred to as "satellite handover"), the terminal (e.g., UE: User Equipment) will resynchronize with the new satellite (the handover satellite) in order to continue communication. The possibility of the base station (e.g., gNB) notifying the terminal of the necessity of resynchronization (e.g., a "notification to re-acquire DL / UL synchronization" message) is under investigation.

[0036] In addition, the timing for satellite handover is being studied, including the timing for notifying the old link to stop (e.g., “t-Service(t-service)”) and the timing for the new link to start (e.g., “t-Start(t-start)”).

[0037] On the other hand, due to the long round-trip time (RTT) of satellite communication, the timing of the base station and the timing of the terminal may differ. Furthermore, the RTT of satellite communication varies depending on the satellite's location, so the RTT before and after satellite handover may differ.

[0038] Furthermore, depending on the network architecture, the beam directions during downlink (transmission) and uplink (reception) (e.g., which satellite the base station transmits to or receives from) may be the same or independent of each other. For example, when switching beam directions using mechanical control such as a parabolic antenna, the downlink and uplink beam directions are the same, and the switching time requires more than 100 ms. On the other hand, when switching beam directions using electronic control such as a phased array antenna, the downlink and uplink beam directions can be set independently, and almost no switching time is required.

[0039] Therefore, further research is needed on the timing of notifications and terminal actions that take into account the round-trip propagation delay in satellite communication and the beam switching between downlink and uplink.

[0040] In one non-limiting embodiment of this disclosure, timing notifications and terminal actions taking into account round-trip propagation time in satellite communications and beam switching between downlink and uplink will be described. For example, in a non-limiting embodiment of this disclosure, the base station notifies the terminal of at least one of the downlink stop timing of the old satellite link (e.g., the communication path before the switch), the uplink stop timing of the old satellite link, the downlink start timing of the new satellite link (e.g., the communication path after the switch), and the uplink start timing of the new satellite link. The terminal resynchronizes based on the notified timing.

[0041] [Overview of Communication Systems]

[0042] One embodiment of the communication system disclosed herein includes a base station 100 and a terminal 200.

[0043] Figure 2 This is a block diagram representing a structural example of a portion of base station 100. Figure 2 In the base station 100 shown, the transmitting unit (e.g., transmitting circuit) transmits control information related to at least one of the following: a first stop timing for downlink communication in the first communication path before the handover, a second stop timing for uplink communication in the first communication path, a first start timing for downlink communication in the second communication path after the handover, and a second start timing for uplink communication in the second communication path. The control unit (e.g., control circuit) controls the resynchronization process in the second communication path based on the control information.

[0044] Figure 3 This is a block diagram representing a structural example of a portion of terminal 200. Figure 3 In the terminal 200 shown, the receiving unit (e.g., receiving circuit) receives information relating to at least one of the following: a first stop timing of downlink communication in the first communication path before the handover; a second stop timing of uplink communication in the first communication path before the handover; a first start timing of downlink communication in the second communication path after the handover; and a second start timing of uplink communication in the second communication path after the handover. The control unit (e.g., control circuit) controls at least one of the downlink and uplink communications based on the information.

[0045] (Implementation Method 1)

[0046] In this embodiment, the following scenario is envisioned: the downlink (downlink or downlink communication) and uplink (uplink or uplink communication) beam directions of base station 100 are the same (e.g., which satellite base station 100 transmits or receives to), and the switching of beams (or satellites) requires a certain amount of time (e.g., time exceeding a threshold), for example, there will be a period (period) during which transmission and reception cannot be performed.

[0047] [Base station structure]

[0048] Figure 4 This is a block diagram illustrating an example of the structure of the base station 100 according to this embodiment. The base station 100 includes, for example, an antenna 101, a wireless receiver 102, a data receiver processing unit 103, a control unit 104, a data transmitter processing unit 105, and a wireless transmitter 106.

[0049] Figure 4 At least one of the data receiving processing unit 103, control unit 104, and data transmitting processing unit 105 shown may be included, for example, in... Figure 2 In the control unit shown. Furthermore... Figure 4 At least one of the antenna 101 and the wireless transmitter 106 shown may be included, for example, in Figure 2 In the sending section shown.

[0050] The wireless receiver 102 performs analog reception processing such as down-conversion, A / D conversion, and filtering on the signal received from the terminal 200 via the antenna 101, as well as digital reception processing, and outputs the processed signal to the data reception processing unit 103. Furthermore, the wireless receiver 102 stops and starts reception according to instructions from the control unit 104.

[0051] Furthermore, the signals received by the wireless receiver 102 may include at least one of the following: Physical Uplink Shared Channel (PUSCH), Physical Uplink Control Channel (PUCCH), Physical Random Access Channel (PRACH), and Sounding Reference Signal (SRS).

[0052] The data receiving and processing unit 103 performs channel estimation, demodulation processing, and decoding processing on the received signal input from the wireless receiving unit 102, for example, to obtain a data sequence (received data).

[0053] The control unit 104 generates, for example, system information (or broadcast information) such as the Master Information Block (MIB) or System Information Block (SIB), and terminal-specific control information (e.g., RRC messages). The control unit 104 outputs the generated information to the data transmission processing unit 105. Furthermore, based on the generated information, the control unit 104 instructs the wireless receiving unit 102 to stop and start receiving, and instructs the wireless transmitting unit 106 to stop and start transmitting.

[0054] The system information may include, for example, information related to the satellite's orbit or position (satellite ephemeris information), general TA parameters for timing advance (TA) of the terminal, and epoch time (the reference time for satellite ephemeris information and general TA parameters), as well as at least one of the control information used for NTN.

[0055] The RRC message may include, for example, resynchronization notification information and timing information related to satellite handover. The timing information may include, for example, information related to the stop timing of downlink and uplink (e.g., transmission and reception) of the satellite link before the handover and the start timing of downlink and uplink (e.g., transmission and reception) of the satellite link after the handover (e.g., information related to satellite handover timing). Furthermore, these may also be included in system information.

[0056] The data transmission processing unit 105 encodes (e.g., low-density parity check (LDPC) encoding) and modulates (e.g., QPSK, 16QAM) the transmitted data and control information input from the control unit 104, and outputs the modulated signal to the wireless transmission unit 106.

[0057] The wireless transmitter 106 performs transmission processing on the signal input from the data transmission processing unit 105, such as D / A conversion, filtering, up-conversion, and amplification, and then transmits the processed wireless signal from the antenna 101. Furthermore, the wireless transmitter 106 stops and starts transmission according to instructions from the control unit 104.

[0058] [Terminal Structure]

[0059] Next, we will explain the structure of terminal 200.

[0060] Figure 5This is a block diagram illustrating an example of the structure of the terminal 200 according to this embodiment. The terminal 200 includes, for example, an antenna 201, a wireless receiver 202, a data receiver processing unit 203, a control unit 204, a timing adjustment unit 205, a data transmission processing unit 206, and a wireless transmitter 207.

[0061] Figure 5 At least one of the data receiving processing unit 203, control unit 204, timing adjustment unit 205, and data transmitting processing unit 206 shown may be included, for example, in... Figure 3 In the control unit shown. Additionally... Figure 5 At least one of the antenna 201 and the wireless receiver 202 shown may be included, for example, in Figure 3 In the receiving section shown.

[0062] The wireless receiving unit 202 performs analog and digital reception processing, such as down-conversion, A / D conversion, and filtering, on the downlink signal received from the base station 100 via the antenna 201, and outputs the processed signal to the data receiving processing unit 203. Additionally, the wireless receiving unit 202 outputs timing-related information, such as synchronization signals (e.g., SSB: Synchronization Signal Block) included in the received signal, to the timing adjustment unit 205. Furthermore, the wireless receiving unit 202 performs resynchronization processing (e.g., re-synchronization or re-acquirement of synchronization) with the base station 100 according to instructions from the control unit 204.

[0063] The data receiving and processing unit 203 performs demodulation and decoding processing on the received signals (e.g., downlink signals such as SSB, PDCCH, or PDSCH) input from the wireless receiving unit 202.

[0064] Control signals (e.g., PDCCH) may include, for example, resource allocation information for downlink data signals (e.g., PDSCH), resource allocation information for uplink data signals (e.g., PUSCH), or PUCCH resource allocation information for sending HARQ-ACKs to the PDSCH. Additionally, control information (e.g., PDCCH) may include, for example, control information for paging. Furthermore, downlink data signals (e.g., PDSCH) may include, for example, user data. Additionally, downlink data signals (e.g., PDSCH) may include, for example, broadcast information such as system information, RRC control information, paging information, MAC control element (MAC CE) control information, RACH responses (e.g., Message 2 or Msg. 2), or information related to TA commands.

[0065] Additionally, the data receiving and processing unit 203 receives and processes information related to satellite handover (e.g., resynchronization notification information, timing information, etc.) contained in broadcast information or RRC control information (e.g., RRC Reconfiguration message), and outputs the processed signal to the control unit 204. Furthermore, the data receiving and processing unit 203 outputs information for NTN (e.g., at least one of satellite ephemeris, general TA parameters, and epoch time) to the control unit 204.

[0066] The control unit 204 acquires the location information (e.g., latitude, longitude, altitude, etc.) of the terminal 200 via a Global Navigation Satellite System (GNSS). Furthermore, the control unit 204 calculates the satellite's orbit or position based on the NTN information (e.g., satellite ephemeris and epoch time information) input from the data receiving and processing unit 203. Then, the control unit 204 calculates a timing adjustment value (e.g., TA value) based on the round-trip time between the terminal 200 and the satellite calculated using the terminal 200's location information and the satellite's orbit or position information, and the round-trip time between the terminal 200 and the satellite calculated using general TA parameters, and outputs the calculated timing adjustment value to the timing adjustment unit 205.

[0067] Furthermore, the control unit 204 outputs a resynchronization-related instruction to the radio receiver 202 based on the satellite handover-related information received from the data reception processing unit 203 (e.g., resynchronization notification information and timing information). Additionally, the control unit 204 can determine the timing for stopping and restarting uplink transmission, and the timing for stopping and restarting at least one of the processes involved in detecting and recovering Radio Link Failure (RLF) (hereinafter also referred to as detection / recovery processing), based on the aforementioned timing information (an example of the operation will be described later). Furthermore, the control unit 204 may also output instructions for stopping and restarting uplink transmission, and stopping and restarting RLF / recovery processing, to the data transmission processing unit 206.

[0068] The timing adjustment unit 205 controls (e.g., adjusts) the transmission timing of the transmission signal (uplink signal) based on information related to reception timing input from the wireless receiving unit 202 and information related to timing adjustment value input from the control unit 204. The timing adjustment unit 205 outputs the timing adjustment-related information to the wireless transmitting unit 207.

[0069] Alternatively, the timing adjustment unit 205 may store information related to the timing of receiving signals used for timing synchronization, such as synchronization signals (e.g., SSB). This timing-related information can be used, for example, when the wireless receiving unit 202 receives data. Furthermore, the timing adjustment unit 205 may store new timing-related information when resynchronization occurs during satellite handover.

[0070] It should be noted that the timing adjustment unit 205 can not only adjust the timing, but also adjust the frequency.

[0071] The data transmission processing unit 206 encodes (e.g., LDPC encoding) and modulates (e.g., QPSK and 16QAM) the input transmission data, and outputs signals mapped to time and frequency resources (e.g., PUSCH, PUCCH, PRACH, or SRS) to the wireless transmission unit 207. Furthermore, the data transmission processing unit 206 can stop / restart transmission to the base station 100 according to an uplink transmission stop / restart instruction from the control unit 204. Additionally, the data transmission processing unit 206 can stop and restart RACH transmission for RLF recovery according to an RLF recovery processing stop and restart instruction from the control unit 204.

[0072] The wireless transmitter 207 performs transmission processing such as D / A conversion, filtering, up-conversion, and amplification on the signal input from the data transmission processing unit 206, and transmits the processed wireless signal from the antenna 201. The wireless transmitter 207 also performs timing adjustment for transmission based on timing information input from the timing adjustment unit 205.

[0073] [Examples of Base Station and Terminal Operations]

[0074] Next, we will explain the operation examples of base station 100 and terminal 200.

[0075] Figure 6 This is a timing diagram illustrating the actions of base station 100 and terminal 200. Figure 6 As an example, this illustrates the situation where the round-trip propagation delay of the satellite link after the satellite handover is shorter than that of the satellite link before the handover.

[0076] Furthermore, as described above, in this embodiment, the downlink and uplink beam directions of the base station 100 are the same.

[0077] like Figure 6 As shown, at time T0, base station 100 stops downlink communication (transmission) and uplink communication (reception) with the current satellite (the satellite before the handover (old satellite)), and starts downlink communication (transmission) and uplink communication (reception) with the new satellite (the satellite after the handover) at time T1.

[0078] exist Figure 6 In the time interval from time T0 to time T1 (in Figure 6 During the time period (referred to as the gap), base station 100 does not receive signals from terminal 200.

[0079] Base station 100 notifies terminal 200 of information related to satellite handover (e.g., resynchronization notification information or timing information). For example, base station 100 notifies terminal 200 of satellite handover-related information, such as HARQ-ACK feedback information, a timing information that is sufficient to allow feedback information to be received from terminal 200 before time T0, a timing amount that allows feedback information to be received from terminal 200 before time T0.

[0080] It should be noted that the timing information may include, for example, time information used to determine time T0 and time T1, or timing information for time T0 and time T1 represented by SFN (System Frame Number) or time slot number. Additionally, base station 100 may notify terminal 200 of information related to the position of the switched satellite (e.g., ephemeris and epoch time) and information related to feeder link delay (e.g., general TA parameters).

[0081] Terminal 200 can, for example, initiate resynchronization processing in the switched satellite link based on information related to the downlink and uplink start timing of the switched satellite link. For example, terminal 200 initiates resynchronization processing after the signal arrives via the switched satellite at time T5.

[0082] Alternatively, for example, the terminal 200 may control the system by not performing uplink communication during a period determined based on the uplink stop timing of the satellite link before the handover and the uplink start timing of the satellite link after the handover.

[0083] For example, it could be the time period between two transmission timings (e.g., Figure 6 During the time period from time T2 to time T4, terminal 200 does not perform uplink transmission. The earlier of the two transmission timings is defined as the transmission timing after time T0 (e.g., the uplink stop timing), calculated based on the satellite position and terminal 200's position before the handover, where the uplink signal transmitted from terminal 200 is received by base station 100 at time T0. The later of the two transmission timings is defined as the transmission timing before time T1, calculated based on the satellite position and terminal 200's position after the handover, where the uplink signal transmitted from terminal 200 is received by base station 100 at time T1. Figure 6 In the example, the transmission timing of terminal 200 is defined as the time when the uplink transmission signal of terminal 200 is received by base station 100 via the satellite before the handover. Figure 6 Uplink transmission stops at time T2. Furthermore, the time when the uplink transmission signal of terminal 200 is received by base station 100 via the switched satellite is the transmission timing at time T1. Figure 6 At time T4, uplink transmission resumes.

[0084] Alternatively, for example, the terminal 200 may control the process by not initiating (or triggering) any processing related to RLF or BeamFailure during a period determined based on the downlink stop timing of the satellite link before the handover and the downlink start timing of the satellite link after the handover.

[0085] exist Figure 6 In the example, during the period from time T3 after the signal transmitted by base station 100 at time T0 arrives at terminal 200 via the satellite before the handover, until time T5 after the signal transmitted by base station 100 at time T1 arrives at terminal 200 via the satellite after the handover, terminal 200 does not receive downlink signals. For example, during this period ( Figure 6 During the time period from time T3 to time T5, the detection / recovery process of RLF or BF will not be initiated (or triggered). For example, after time T5, the terminal 200 may initiate the detection / recovery process of RLF or BF after the resynchronization in the switched satellite link is completed.

[0086] For example, terminal 200 can Figure 6 The RLF and BF determination processes are not performed during the time period from time T3 to time T5. Alternatively, the timer (time alignment timer, etc.) used for RLF and BF determination can be stopped at time T3.

[0087] In addition, although Figure 6 The document describes the scenario where terminal 200 resumes uplink transmission at time T4, but it is not limited to this; it can also resume uplink transmission after time T4. For example, terminal 200 could control the transmission by not performing uplink communication for a period determined based on the uplink stop timing of the satellite link before the handover and the downlink start timing of the satellite link after the handover. Figure 6 In the example, since the downlink signal of the switched satellite link will not be received by terminal 200 before time T5, it is difficult for terminal 200 to calculate the propagation loss used for transmit power control. Therefore, it is also possible that terminal 200 does not perform uplink communication during the time period from time T2 to time T5, and resumes uplink transmission after time T5.

[0088] In addition, although Figure 6 The document describes the scenario where RLF detection / recovery processing is not initiated after time T3, but it is not limited to this. It can also be configured to not initiate RLF detection / recovery processing from a timing point before time T3. For example, terminal 200 could control the process by not triggering RLF or BF-related processing during a time period determined based on the uplink stop timing of the satellite link before the handover and the downlink start timing of the satellite link after the handover. Figure 6In the example, after time T2, the uplink signal is not received at base station 100, and the RACH signal used for RLF recovery is not received (or is not active). Therefore, terminal 200 can be configured not to initiate RLF detection / recovery processing after the uplink becomes unavailable, i.e., time T2, or it can be configured to perform RLF detection processing but not RLF recovery processing during the period from time T2 to time T3. In this case, RLF recovery processing can be performed after resynchronization in terminal 200.

[0089] The above describes the operation examples of base station 100 and terminal 200.

[0090] In this way, base station 100 sends information related to the stop timing of downlink communication in the communication path before handover (e.g., the satellite link before handover), the stop timing of uplink communication in the communication path before handover, and the start timing of downlink communication in the communication path after handover (e.g., the satellite link after handover). Then, terminal 200 controls the resynchronization process in the communication path after handover based on the information sent from base station 100.

[0091] In this way, notification information related to resynchronization during satellite handover, along with information related to the stop timing of downlink and uplink satellite links before handover and the start timing of downlink and uplink satellite links after handover, are communicated to terminal 200. Therefore, terminal 200 can determine the appropriate timing for initiating resynchronization in the post-handover satellite link, thereby reducing the power consumption of the resynchronization process.

[0092] Furthermore, terminal 200 can determine the time period during which uplink signals will not reach base station 100 during satellite handover. Therefore, terminal 200 can stop and restart uplink transmission at appropriate timings during satellite handover, thereby reducing interference to neighboring cells and reducing uplink transmission power consumption.

[0093] In addition, terminal 200 can determine the time period during which downlink signals will not reach terminal 200 during satellite handover, and therefore can stop and restart the detection / recovery process of RLF or BF at appropriate time intervals.

[0094] As described above, according to this embodiment, the communication timing in the terminal 200 can be appropriately controlled by taking into account the round-trip propagation delay time in satellite communication and the beam switching between downlink and uplink.

[0095] (Implementation Method 2)

[0096] The structure of the base station 100 and terminal 200 in this embodiment can be the same as that in embodiment 1.

[0097] In this embodiment, it is envisioned that the base station 100 can switch beams (e.g., satellites) instantaneously, similar to the case of a phased array antenna. Furthermore, regarding the base station 100, there are cases where the downlink and uplink beam directions (e.g., which satellite the base station 100 transmits to or receives from) are the same, and there are cases where the downlink and uplink beam directions can be set independently.

[0098] This describes the different operations of the base station 100 and terminal 200 in this embodiment compared to those in embodiment 1.

[0099] The base station 100 (e.g., the control unit 104) generates information related to the satellite handover timing, including the stop timing of downlink (e.g., transmission) of the satellite link before handover, the stop timing of uplink (e.g., reception) of the satellite link before handover, the start timing of downlink (e.g., transmission) of the satellite link after handover, and the start timing of uplink (e.g., reception) of the satellite link after handover, and notifies the terminal 200 of this information.

[0100] Terminal 200 (e.g., wireless receiver 202 and data receiver processing unit 203) receives information related to satellite handover timing from base station 100, including the stop timing of downlink (e.g., transmission) of the satellite link before handover, the stop timing of uplink (e.g., reception) of the satellite link before handover, the start timing of downlink (e.g., transmission) of the satellite link after handover, and the start timing of uplink (e.g., reception) of the satellite link after handover. Furthermore, based on the received information related to satellite handover timing, terminal 200 (e.g., control unit 204 and timing adjustment unit 205) determines the timing for resynchronization, uplink transmission stop / restart, and RLF detection / recovery processing as described in Embodiment 1.

[0101] Next, we will explain the operation examples of base station 100 and terminal 200.

[0102] Figure 7 This is a timing diagram illustrating the actions of base station 100 and terminal 200. Figure 7 In this example, the downlink and uplink beam directions in base station 100 are the same.

[0103] like Figure 7 As shown, base station 100 stops downlink communication (transmission) with the current satellite (the satellite before the handover (e.g., the old satellite)) at time T0, and stops uplink communication (reception) with the current satellite (the satellite before the handover) at time T1.

[0104] In addition, such as Figure 7As shown, base station 100 starts downlink communication (transmission) with the new satellite (the switched satellite) at time T2 and starts uplink communication (reception) with the new satellite (the switched satellite) at time T3.

[0105] exist Figure 7 During the time period from time T1 to time T3, base station 100 does not receive signals from terminal 200.

[0106] Base station 100 notifies terminal 200 of information related to satellite handover (e.g., resynchronization notification information or timing information). For example, base station 100 notifies terminal 200 of satellite handover-related information, such as HARQ-ACK feedback information, a timing information that is sufficient to allow feedback information to be received from terminal 200 before time T1, a timing amount that allows feedback information to be received from terminal 200 before time T1.

[0107] It should be noted that the timing information may include, for example, time information used to determine time T0, time T1, time T2, and time T3 (e.g., sometimes also referred to as t-ServiceDL, t-ServiceUL, t-StartDL, t-StartUL), or timing information represented by SFN and / or time slot numbers. Furthermore, base station 100 may notify the terminal of information related to the location of the switched satellites (e.g., ephemeris and epoch time) and information related to feeder link delay (e.g., general TA parameters).

[0108] Terminal 200 can, for example, initiate resynchronization processing in the switched satellite link based on information related to the downlink and uplink start timing of the switched satellite link. For example, terminal 200 initiates resynchronization processing after the signal arrives via the switched satellite at time T6.

[0109] Alternatively, for example, the terminal 200 may control the system by not performing uplink communication during a period determined based on the uplink stop timing of the satellite link before the handover and the uplink start timing of the satellite link after the handover.

[0110] For example, it could be the time period between two transmission timings (e.g., Figure 7During the time period from time T4 to time T6, terminal 200 does not perform uplink transmission. The earlier of the two transmission timings is the transmission timing calculated based on the propagation delay of the satellite position and terminal 200 before the handover, with that as the boundary. After that, the transmission timing for uplink signals transmitted from terminal 200 that are received by base station 100 is after time T1 (e.g., the uplink stop timing). The later of the two transmission timings is the transmission timing calculated based on the propagation delay of the satellite position and terminal 200 after the handover, with that as the boundary. Before that, the transmission timing for uplink signals transmitted from terminal 200 that are received by base station 100 is before time T3. Figure 7 In the example, the transmission timing of the uplink transmission signal sent by terminal 200 is defined as time T1, when the signal is received by base station 100 via the satellite before the handover. Figure 7 At time T4, uplink transmission stops. Furthermore, the transmission timing at time T3 is when the uplink transmission signal from terminal 200 is received by base station 100 via the switched satellite. Figure 7 At time T6, uplink transmission resumes.

[0111] Furthermore, if, at a timing point (e.g., time T6) when the uplink transmission signal from terminal 200 is received by base station 100 via the switched satellite at time T3, but terminal 200 has not yet received the downlink signal (e.g., SSB, etc.) via the switched satellite, it becomes difficult to calculate the propagation loss used for transmission power control. Therefore, terminal 200 may, for example, restart uplink transmission at a timing point after time T6, after receiving the downlink signal.

[0112] Alternatively, for example, terminal 200 may control the process by not initiating (or triggering) processes related to RLF or BF during a period determined based on the downlink stop timing of the satellite link before the handover and the downlink start timing of the satellite link after the handover.

[0113] exist Figure 7 In the example, during the period from time T5 after the signal transmitted by base station 100 at time T0 arrives at terminal 200 via the satellite before the handover, until time T6 after the signal transmitted by base station 100 at time T2 arrives at terminal 200 via the satellite after the handover, terminal 200 does not receive downlink signals. For example, during this period ( Figure 7 During the time period from time T5 to time T6, the detection / recovery process of RLF or BF will not be initiated (or triggered). For example, after time T6, the terminal 200 may initiate the detection / recovery process of RLF or BF after the resynchronization in the switched satellite link is completed.

[0114] For example, terminal 200 can Figure 7 The RLF and BF determination processes are not performed during the time period from time T5 to time T6. Alternatively, the timer (time alignment timer, etc.) used for RLF and BF determination can be stopped at time T5.

[0115] Alternatively, terminal 200 may control the process by not triggering RLF or BF-related processing during a period determined based on the uplink stop timing of the satellite link before the handover and the downlink start timing of the satellite link after the handover. Figure 7 In the example, the uplink transmission signal sent from terminal 200 via the satellite before the handover after time T4 is not received by base station 100. Therefore, it is possible that terminal 200 does not trigger RLF detection / recovery processing during the time period from time T4 to time T6.

[0116] In addition, Figure 7 The example shown illustrates information related to satellite handover timing, including the downlink stop timing of the satellite link before handover, the uplink stop timing of the satellite link before handover, the downlink start timing of the satellite link after handover, and the uplink start timing of the satellite link after handover. Figure 7 The example provided is a method for notifying terminal 200 at each time point (T0, T1, T2, T3), but it is not limited to this.

[0117] For example, such as Figure 8 As shown, the three timings—the stop timing (e.g., t-ServiceUL) of the uplink (e.g., receive) of the satellite link before the handover, the start timing (e.g., t-StartDL) of the downlink (e.g., transmit) of the satellite link after the handover, and the start timing (e.g., t-StartUL) of the uplink (e.g., receive) of the satellite link after the handover—can be set to the same value. In this case, the base station 100 can notify the terminal 200 of information related to the satellite handover timing, including the stop timing (e.g., time T0) of the downlink (e.g., transmit) of the satellite link before the handover, and the aforementioned three timings (e.g., time T1 (=T2=T3)).

[0118] Alternatively, base station 100 may notify terminal 200 of satellite handover timing-related information, including the stop timing (e.g., time T0) of the downlink (e.g., transmission) of the satellite link before the handover, without notifying terminal 200 of other timings (e.g., times T1=T2=T3). In this case, terminal 200 can estimate timing T1 (=T2=T3) based on the propagation delay times of the satellite links before and after the handover.

[0119] Next, we will explain the situation where the downlink and uplink beam directions of base station 100 can be set independently.

[0120] Figure 9 This is a timing diagram illustrating the actions of base station 100 and terminal 200. Figure 9 For example, the downlink and uplink beam directions of base station 100 can be set independently.

[0121] exist Figure 9 In the example, the uplink stop timing before the handover is almost the same as the uplink start timing after the handover (e.g., time T2 = time T3).

[0122] In addition, Figure 9 In the example, between the start timing of the downlink after the handover (time T1) and the stop timing of the uplink before the handover (time T2), the uplink and downlink communicate using different beams (e.g., different satellites).

[0123] In addition, Figure 9 In the example, a difference (gap) can be set between the stop timing of the downlink of the satellite before the handover (e.g., time T0) and the start timing of the downlink of the satellite after the handover (e.g., time T1) to avoid overlap between the reception of the downlink of the satellite before the handover and the reception of the downlink of the satellite after the handover in the terminal 200.

[0124] exist Figure 9 In the example, base station 100 may, for instance, schedule the stop of the downlink with the satellite before the handover (e.g., t-ServiceDL). Figure 9 The time in the middle is T0), and the start timing of the downlink of the switched satellite (e.g., t-StartDL). Figure 9 The timing of the uplink switching (e.g., t-ServiceUL and t-StartUL) is time T1. Figure 9 The information related to time T2 (=T3) is notified to terminal 200.

[0125] exist Figure 9 As an example, terminal 200 may control the system to not perform uplink communication during a time period determined based on the uplink stop timing of the satellite link before the handover and the uplink start timing of the satellite link after the handover (e.g., the time period from time T4 to time T6).

[0126] In addition, Figure 9As an example, terminal 200 may control the system to not trigger processing related to RLF or BF during a time period determined based on the uplink stop timing of the satellite link before the handover and the downlink start timing of the satellite link after the handover (or the resynchronization establishment timing of the satellite link after the handover) (e.g., a time period from time T4 to time T5).

[0127] In addition, Figure 9 The example illustrates the case where the propagation delay of the satellite link after the handover is shorter than that of the satellite link before the handover. However, the propagation delay of the satellite link after the handover can also be longer than that of the satellite link before the handover, or they can be the same. When the propagation delay of the satellite link after the handover is longer than that of the satellite link before the handover, the information that the start timing (time T1) of the downlink of the satellite after the handover is the same as the stop timing (time T0) of the downlink of the satellite before the handover (T0(=T1)), as well as information related to the stop timing (time T2) of the uplink before the handover and the start timing (time T3) of the uplink after the handover, can be notified to the terminal 200.

[0128] In this way, base station 100 sends information related to the stop timing of downlink communication in the communication path before handover (e.g., the satellite link before handover), the stop timing of uplink communication in the communication path before handover, the start timing of downlink communication in the communication path after handover (e.g., the satellite link after handover), and the start timing of uplink communication in the communication path after handover. Then, terminal 200 controls the resynchronization process in the communication path after handover based on the information sent from base station 100.

[0129] In this way, the resynchronization notification information related to satellite handover, along with the respective DL (transmit) and UL (receive) information related to the stop timing of the satellite link before handover and the start timing of the satellite link after handover, are notified to the terminal 200. Therefore, the terminal 200 can determine the appropriate timing for initiating resynchronization in the satellite link after handover, thereby reducing the power consumption of the resynchronization process.

[0130] Furthermore, terminal 200 can determine the time period during which uplink signals will not reach base station 100 during satellite handover. Therefore, terminal 200 can stop and restart uplink transmission at appropriate timings during satellite handover, thereby reducing interference to neighboring cells and reducing uplink transmission power consumption.

[0131] In addition, terminal 200 can determine the time period during which downlink signals will not reach terminal 200 during satellite handover, and therefore can stop and restart the detection / recovery process of RLF or BF at appropriate time intervals.

[0132] As described above, according to this embodiment, the communication timing in the terminal 200 can be appropriately controlled by taking into account the round-trip propagation delay time in satellite communication and the beam switching between downlink and uplink.

[0133] (Implementation Method 3)

[0134] The structure of the base station 100 and terminal 200 in this embodiment can be the same as that in embodiment 1.

[0135] In this embodiment, base station 100 notifies terminal 200 of information related to the downlink start timing for the switched satellite (e.g., t-StartDL), but not of information related to other timings (e.g., downlink and uplink stop timing for the satellite before the switch and uplink start timing for the satellite after the switch).

[0136] This describes the different operations of the base station 100 and terminal 200 in this embodiment compared to those in embodiment 1.

[0137] The base station 100 (e.g., the control unit 104) generates information related to the start timing of downlink (e.g., transmission) of the satellite link after the handover, as information related to satellite handover timing, and notifies the terminal 200.

[0138] Terminal 200 (e.g., wireless receiver 202 and data receiver processing unit 203) receives information from base station 100 related to the start timing of downlink (e.g., transmission) of the satellite link after handover, as information related to satellite handover timing. Furthermore, terminal 200 (e.g., control unit 204 and timing adjustment unit 205) determines the timing for resynchronization, uplink transmission stop / restart, and RLF detection / recovery processing as described in Embodiment 1 based on the received satellite handover timing information.

[0139] Next, we will explain the operation examples of base station 100 and terminal 200.

[0140] Figure 10 This is a timing diagram representing an example of the operation of base station 100 and terminal 200. Figure 10 As an example, this illustrates a situation where the downlink and uplink beam directions (e.g., which satellite the base station 100 transmits and receives from) in base station 100 are the same, and the switching of the beam (e.g., the satellite) requires a certain amount of time (e.g., a time exceeding a threshold).

[0141] like Figure 10As shown, in the same manner as in Implementation 1, base station 100 stops downlink communication (transmission) and uplink communication (reception) to the current satellite (the satellite before the handover (e.g., the old satellite)) at time T0, and starts downlink communication (transmission) and uplink communication (reception) to the new satellite (the satellite after the handover) at time T1.

[0142] Base station 100 notifies terminal 200 of information related to satellite handover (e.g., resynchronization notification information or timing information). For example, base station 100 notifies terminal 200 of satellite handover-related information (e.g., resynchronization notification information or timing information) a sufficient amount of time earlier than the timing that would enable the reception of feedback information from terminal 200 before time T0. This feedback information is such as HARQ-ACK feedback information related to the satellite handover.

[0143] It should be noted that the timing information may include, for example, time information used to determine time T1 (information related to satellite switching timing).

[0144] Terminal 200 may initiate resynchronization processing in the switched satellite link based on information related to the downlink start timing (e.g., time T1) of the switched satellite link. For example, terminal 200 may initiate resynchronization processing after the downlink signal from base station 100 arrives via the switched satellite at time T5.

[0145] Alternatively, for example, terminal 200 may control the system to refrain from uplink communication during a period determined based on the resynchronization notification information related to satellite handover and the downlink start timing of the switched satellite link. For instance, after receiving the resynchronization notification information related to satellite handover, terminal 200 may refrain from uplink transmission during the period from when it resynchronizes with the switched satellite (e.g., the period from time T2 to T5). Alternatively, after receiving the resynchronization notification information related to satellite handover, terminal 200 may refrain from uplink transmission during the period from when the uplink signal via the switched satellite is received by base station 100 (e.g., the period from time T2 to T4).

[0146] Alternatively, for example, the terminal 200 may control the process by not initiating (or triggering) the processing related to RLF or BF during a time period determined based on the notification information of resynchronization related to satellite handover and the downlink start timing of the satellite link after handover (e.g., a time period from time T2 to time T5).

[0147] Furthermore, although it is stated that the terminal 200 stops uplink transmission after receiving a resynchronization notification related to satellite handover, it is not limited to this. Alternatively, the terminal 200 may stop uplink transmission after receiving a resynchronization notification related to satellite handover and sending a HARQ-ACK to it.

[0148] Furthermore, although the above example illustrates a situation where the downlink and uplink beam directions are the same and the beam switching (e.g., satellite) takes a certain amount of time, it is not limited to this. The same action can be applied even when the uplink and downlink beam directions can be set independently, or when the beam switching does not take time.

[0149] In this way, base station 100 sends information related to the timing of the start of downlink communication in the switched communication path (e.g., the switched satellite link). Then, terminal 200 controls the resynchronization process in the switched communication path based on the information sent from base station 100.

[0150] In this way, information related to the timing of the start of the switched satellite link is communicated to the terminal 200. Therefore, the terminal 200 is able to determine the appropriate timing for initiating resynchronization in the switched satellite link, thereby reducing the power consumption of the resynchronization process.

[0151] In addition, after receiving a resynchronization notification related to satellite handover, the terminal 200 stops uplink transmission, thereby reducing interference to neighboring cells and reducing uplink transmission power consumption.

[0152] (Implementation Method 4)

[0153] The structure of the base station 100 and terminal 200 in this embodiment can be the same as that in embodiment 1.

[0154] In this embodiment, base station 100 notifies terminal 200 of information related to the downlink stop timing for the satellite before handover (e.g., t-ServiceDL), but not of information related to other timings (e.g., uplink stop timing for the satellite before handover and downlink and uplink start timing for the satellite after handover).

[0155] This describes the different operations of the base station 100 and terminal 200 in this embodiment compared to those in embodiment 1.

[0156] The base station 100 (e.g., the control unit 104) generates information related to the stop timing of downlink (e.g., transmission) of the satellite link before the handover, as information related to satellite handover timing, and notifies the terminal 200.

[0157] Terminal 200 (e.g., wireless receiver 202 and data receiver processing unit 203) receives information from base station 100 related to the stop timing of downlink (e.g., transmission) of the satellite link before the handover, as information related to satellite handover timing. Furthermore, terminal 200 (e.g., control unit 204 and timing adjustment unit 205) determines the timing for resynchronization, uplink transmission stop / restart, and RLF detection / recovery processing as described in Embodiment 1 based on the received satellite handover timing information.

[0158] Next, we will explain the operation examples of base station 100 and terminal 200.

[0159] Figure 11 This is a timing diagram illustrating the actions of base station 100 and terminal 200. Figure 11 As an example, this illustrates a situation where the downlink and uplink beam directions of base station 100 (e.g., which satellite base station 100 transmits and receives to) are the same, and the switching of the beam (e.g., the satellite) requires a certain amount of time (e.g., a time exceeding a threshold).

[0160] like Figure 11 As shown, in the same manner as in Implementation 1, base station 100 stops downlink communication (transmission) and uplink communication (reception) to the current satellite (the satellite before the handover (e.g., the old satellite)) at time T0, and starts downlink communication (transmission) and uplink communication (reception) to the new satellite (the satellite after the handover) at time T1.

[0161] Base station 100 notifies terminal 200 of information related to satellite handover (e.g., resynchronization notification information or timing information). For example, base station 100 notifies terminal 200 of satellite handover-related information, such as HARQ-ACK feedback information, a timing information that is sufficient to allow feedback information to be received from terminal 200 before time T0, a timing amount that allows feedback information to be received from terminal 200 before time T0.

[0162] It should be noted that the timing information may include, for example, time information used to determine time T0 (information related to satellite switching timing).

[0163] Terminal 200 can, for example, determine the downlink stop timing (e.g., time T0) based on the satellite link before the handover. Figure 11 The information (corresponding to the uplink stop timing of the satellite link before the handover) is used to initiate resynchronization processing in the satellite link after the handover. For example, terminal 200 initiates resynchronization processing after time T3, where time T3 is the propagation delay calculated based on the satellite positions before the handover and the terminal 200's position, and the time when the signal sent from base station 100 at time T0 will be received by terminal 200.

[0164] Alternatively, for example, the terminal 200 may control the system by not performing uplink communication during a period determined by the downlink stop timing of the satellite link before the handover and the resynchronization establishment timing of the satellite link after the handover.

[0165] For example, terminal 200 may not transmit uplink data for a period of time (e.g., time period T2 to T5) from a transmission timing (e.g., time T2) until resynchronization with the switched satellite (e.g., resynchronization establishment). This transmission timing is based on the propagation delay calculated from the position of the satellite before the switch and the position of terminal 200. The time when the transmitted signal from terminal 200 is received by base station 100 will be the transmission timing T0.

[0166] Alternatively, for example, the terminal 200 may control the process by not initiating (or triggering) processes related to RLF or BF during a time period determined based on the downlink stop timing of the satellite link before the handover and the resynchronization establishment timing of the satellite link after the handover (e.g., a time period from time T2 to time T5).

[0167] Furthermore, although the above examples illustrate that the downlink and uplink beam directions (e.g., which satellite to transmit to and receive from) are the same, and that beam switching (e.g., satellite) takes a certain amount of time, this is not the only case. The same action can be applied even when the uplink and downlink beam directions can be set independently, or when beam switching does not take time.

[0168] In cases where beam switching requires no time, for example, it can be as follows: Figure 12 As shown, the start of the period during which uplink transmission is not performed is set at the time when terminal 200 receives the resynchronization notification information related to satellite handover (or at the time of sending the HARQ-ACK for that notification information) (e.g., time T4). Alternatively, the start of the period during which uplink transmission is not performed can be set at the later of two timings: the time when the terminal 200's transmission signal is received by base station 100 at time T0, and the time when the resynchronization notification information related to satellite handover is received. In this way, terminal 200 can continue uplink transmission for as long as possible.

[0169] In this way, base station 100 sends information related to the timing of downlink communication termination in the communication path before handover (e.g., the satellite link before handover). Then, terminal 200 controls the resynchronization process in the communication path after handover based on the information sent from base station 100.

[0170] In this way, information related to the timing of the satellite link's shutdown before the handover is communicated to the terminal 200. Therefore, the terminal 200 can determine the appropriate timing for initiating resynchronization in the satellite link after the handover based on the timing of the satellite link's shutdown before the handover, thereby reducing the power consumption of the resynchronization process.

[0171] In addition, after receiving a resynchronization notification related to satellite handover, the terminal 200 stops uplink transmission, thereby reducing interference to neighboring cells and reducing uplink transmission power consumption.

[0172] The above describes various embodiments of this disclosure.

[0173] (Other implementation methods)

[0174] Furthermore, in Embodiment 3, base station 100 notifies terminal 200 of information related to the downlink start timing for the switched satellite (e.g., t-StartDL), and in Embodiment 4, base station 100 notifies terminal 200 of information related to the downlink stop timing for the previous satellite (e.g., t-ServiceDL). However, base station 100 may also notify terminal 200 of both. Terminal 200 can then perform the action described in either Embodiment 3 or Embodiment 4.

[0175] Furthermore, while the above embodiments describe the case where RLF detection / recovery processing is not initiated during a specified time period, this is not a limitation. For example, the timer related to RLF could be stopped during that time period. Additionally, RLF detection could be performed but recovery processing not performed during a period when downlink signals reach terminal 200 but uplink signals are not received at base station 100. In this case, RLF recovery processing can be performed after resynchronization is established.

[0176] Furthermore, while the above embodiments describe the time periods during which RLF detection or triggering is not performed, the same time periods may also be applied to BF (beam failure) detection or triggering, or synchronization loss detection or triggering.

[0177] Furthermore, the timer used for determining RLF and BF in the above embodiments can also be a timer related to uplink synchronization.

[0178] Furthermore, in the above embodiments, as a recovery process from RLF and BF, terminal 200 can re-receive SSB or transmit PRACH.

[0179] Furthermore, during the uplink transmission suspension period in the above embodiments, terminal 200 may stop all uplink transmissions, or it may only stop partial uplink transmissions. For example, terminal 200 may stop the periodic uplink transmissions set by base station 100, but may continue the dynamic uplink transmissions allocated by DCI (e.g., transmissions of PUSCH, PUCCH, SRS, etc.). Furthermore, periodic uplink transmissions include configured grants, periodic PUCCH, periodic SRS, etc.

[0180] Furthermore, as terminal actions in the above embodiments, the timing control of resynchronization, uplink transmission stop and restart, and RLF determination / recovery processing is described. All of these timing controls can be implemented, or at least one timing control can be implemented without implementing the others.

[0181] Furthermore, in the above embodiments, the information related to the start timing of the downlink (transmission) and uplink (reception) for the switched satellite may also be information related to offset (or gap), which is the offset (or gap) from the start timing of the downlink (transmission) and uplink (reception) for the satellite before the switch.

[0182] Furthermore, in the above embodiments, it is described that the terminal 200 does not perform uplink transmission before resynchronizing with the switched satellite, but it is not limited to this. For example, the terminal 200 may also resume uplink transmission after receiving the SSB via the switched satellite.

[0183] In addition, in the above embodiments, the following information may also be notified to the terminal 200: information indicating whether the stop or start timing is the same in the downlink and uplink, or information indicating which of the downlink and uplink the stop (or start) occurs earlier.

[0184] Furthermore, in the above embodiments, the timing-related information notified to the terminal 200 can be represented by absolute time such as UTC (Coordinated Universal Time), or by SFN (System Frame Number) or time slot number. Since timing is typically managed by SFN or time slot number in the terminal 200, using SFN or time slot number simplifies timing management within the terminal.

[0185] Furthermore, in the above embodiments, the terminal 200 can determine whether to perform at least one of the following actions within a specified time period based on the notification (configuration) from the base station 100: an action of "not performing uplink transmission" (or a stop and restart action), and an action of "not performing RLF detection or triggering". Additionally, the notification from the base station 100 can be sent to the terminal 200 as System Information (SIB).

[0186] In addition, in the above embodiments, the terminal 200 performs resynchronization processing on the switched satellites. If the resynchronization process is not completed within a specified time, it can be determined as an RLF (Recurrent Leak) and a reconnection process can be initiated. Alternatively, the terminal 200 can switch to the RRC_IDLE state and perform cell search and initial connection processing. The specified time can be managed by a timer inside the terminal 200, or a timer value notified from the base station 100 can be used.

[0187] Furthermore, resynchronization notifications do not necessarily need to be explicit. For example, they can be implicitly communicated through timing information. For instance, if base station 100 notifies terminal 200 of timing information, terminal 200 will perform resynchronization processing according to the notified timing.

[0188] Furthermore, the timing information can be common information among terminals 200 within the cell (e.g., information included in system information), or it can be information that differs for each terminal 200 (information that is individually notified to each terminal). In the latter case, PRACH conflicts or congestion caused by many terminals 200 sending PRACH in a short period of time can be avoided or mitigated.

[0189] Additionally, at least one of the satellite ephemeris information, general TA parameters, and epoch time associated with the switched satellite can be notified to the terminal 200 in advance, or it can be notified via SIB after the switch. In the former case, the terminal 200 can send an uplink signal before receiving a downlink signal, and can establish resynchronization in a short time. In the latter case, the terminal 200 receives the SIB (e.g., SIB19 associated with the NTN) during resynchronization and performs PRACH transmission based on information such as satellite ephemeris information, general TA parameters, or epoch time.

[0190] Furthermore, in the above embodiments, an example is shown where the start timing of the switched satellite is later than the stop timing of the satellite before the switch, but the start timing of the switched satellite may also be earlier than the stop timing of the satellite before the switch (i.e., it may be an earlier timing).

[0191] Furthermore, in the above embodiments, one or more pieces of information, including information about whether the PCI has changed, information about whether the satellite or feeder link has switched, and information about whether satellite coverage has been interrupted, can be notified from the base station 100 to the terminal 200 along with timing information. The terminal 200 can then perform actions based on this information, such as: performing a cell (PCI) search after the notified timing, resynchronizing based on the same PCI, or entering sleep mode.

[0192] In addition, in the above embodiments, the start timing information of the switched satellite can also be replaced with the timing information of the terminal 200 starting resynchronization processing after the switch.

[0193] The satellite before the handover can be called the source satellite or the serving satellite. The satellite after the handover can be called the target satellite.

[0194] Furthermore, the above embodiments are not dependent on the structure of the ground station equipment (ground gateway or ground station) and can be applied in any embodiment.

[0195] Alternatively, the actions and notification content of implementation methods 1 to 4 can be configured on the network.

[0196] Furthermore, the above embodiments can be applied regardless of the state of the terminal 200. For example, the above embodiments can be applied regardless of whether the terminal 200 is in the state of RRC_CONNECTED, RRC_INACTIVE, or RRC_IDLE.

[0197] In addition, in the above embodiments, if a paging occurs (e.g., a call from terminal 200) during the downlink stop time period of base station 100, for example, during the time period from the end of the satellite link before the handover to the start of the satellite link after the handover, then in the next paging cycle or paging opportunity after that time period (e.g., after the start of the satellite link after the handover), base station 100 sends paging information and terminal 200 receives paging information.

[0198] Furthermore, although examples of actions during satellite switching have been described in the above embodiments, they can also be applied when switching feeder link ground stations (ground gateways, etc.) without switching satellites.

[0199] Furthermore, although the above embodiments primarily target NTN, they can also be applied to non-NTN devices. For example, they can be used when modifying the relay device for communication to terminal 200.

[0200] Furthermore, the above-described implementation methods can be applied not only to NTN based on the NR specification, but also to NTN based on NB-IoT and MTC (LTE).

[0201] One embodiment of this disclosure can be used for different categories of satellite communications, such as low Earth orbit (LEO), medium Earth orbit (MEO), high Earth orbit (HEO), or geostationary Earth orbit (GEO) satellites, which are at different altitudes from the Earth's surface.

[0202] Furthermore, in the above embodiments, the satellite ephemeris information, which is information related to the satellite's position, can be broadcast by the system information or pre-stored in the terminal 200. Additionally, the satellite ephemeris information can be updated when communication is possible. Furthermore, the terminal 200 can also use information different from the satellite ephemeris information to determine the satellite's position.

[0203] Furthermore, while examples of using GNSS such as GPS (e.g., position detection using satellite signals) have been described in the above embodiments, the methods are not limited to this. For example, position detection using terrestrial cellular base stations, using WiFi or Bluetooth signals, using accelerometers, or a combination of these detection methods can also be performed. Additionally, altitude information can be obtained from barometric pressure sensors or the like.

[0204] Furthermore, in the above embodiments, a cell can be an area defined based on the received power of the SSB or Channel State Information-Reference Signal (CSI-RS) transmitted by the base station (or satellite), or it can be an area defined based on geographical location. Additionally, the cell in the above embodiments can be replaced with a beam defined by the SSB.

[0205] In addition, satellite ephemeris information and general TA parameter information can be notified as “EpochTime” and “TAInfo” respectively in the NTN-Config of SIB19.

[0206] In addition, in the above embodiments, the base station can also be replaced by a network.

[0207] In addition, in the above embodiments, the terminal 200 may use other signals such as CSI-RS instead of SSB signals to perform reception quality measurements.

[0208] Furthermore, although the above embodiments describe uplink transmission from terminal 200 to base station 100, one embodiment of this disclosure is not limited thereto, and can also be applied to downlink transmission from base station 100 to terminal 200, or data in links (e.g., side links) between terminals 200.

[0209] Furthermore, one embodiment of this disclosure can be applied without relying on satellite categories such as GEO, MEO, LEO, or HEO. Additionally, one embodiment of this disclosure can also be applied to non-terrestrial communications such as HAPS or drone base stations.

[0210] Furthermore, although the NTN environment (e.g., a satellite communication environment) has been described in the above embodiments, this disclosure is not limited thereto. This disclosure can also be applied to other communication environments (e.g., at least one terrestrial cellular environment of LTE and NR). For example, one embodiment of this disclosure can also be applied to terrestrial communication in environments such as those with large cell sizes and longer propagation delays (e.g., above a threshold) between base station 100 and terminal 200.

[0211] Furthermore, in the above embodiments, the satellite communication method can be a structure where the base station function exists on the satellite (e.g., a "regenerative satellite"), or a structure where the base station function exists on the ground, and the communication between the base station and the terminal is relayed by the satellite (e.g., a "transparent satellite"). For example, in one embodiment of this disclosure, the downlink and uplink can also be links between the terminal and the satellite, or links via the satellite.

[0212] Furthermore, the method of notifying control information from base station 100 to terminal 200 is not limited to the above examples. It can be notified (or broadcast, indicated, or set) by at least one of system information such as MIB and SIB, RRC control information, MAC control information, and downlink control information (DCI). It can also be preset to terminal 200, or it can be pre-specified in the standard.

[0213] The base station can be referred to as "gNodeB" or "gNB". Additionally, the terminal can be referred to as "UE".

[0214] Time resource units such as system frames and subframes can also be replaced with time slots, time slots, micro-slots, frames, subframes, etc.

[0215] In addition, the term "...part" in the above embodiments can also be replaced with other terms such as "...circuitry", "...device", "...unit" or "...module".

[0216] (Replenish)

[0217] Information indicating whether terminal 200 supports the functions, actions, or processes shown in the above embodiments can also be sent (or notified) by terminal 200 to base station 100 as capability information or capability parameters of terminal 200.

[0218] The capability information may also include information elements, each individually indicating whether the terminal 200 supports at least one of the functions, actions, and processes described in the above embodiments. Alternatively, the capability information may include information elements indicating whether the terminal 200 supports a combination of two or more of the functions, actions, and processes described in the above embodiments.

[0219] Base station 100 can, for example, determine (or decide or envision) the functions, actions, or processes supported (or not supported) by the source terminal 200, based on capability information received from terminal 200. Base station 100 can implement actions, processes, or controls corresponding to the determination results based on the capability information. For example, base station 100 can control communication toward NTN based on the capability information received from terminal 200.

[0220] It should be noted that terminal 200 does not support some of the functions, actions, or processes shown in the above embodiments. Alternatively, in terminal 200, such a portion of the functions, actions, or processes may be restricted. For example, information or requests related to such restrictions may also be notified to base station 100.

[0221] Information related to the capabilities or limitations of terminal 200 may be defined in a standard, or may be implicitly communicated to base station 100 in association with information known to base station 100 or information sent to base station 100.

[0222] (Control signal)

[0223] In this disclosure, the downlink control signal (or downlink control information) associated with an embodiment of this disclosure may be, for example, a signal (or information) transmitted in the Physical Downlink Control Channel (PDCCH) at the physical layer, or a signal (or information) transmitted in a higher-layer Medium Access Control Element (MAC CE) or Radio Resource Control (RRC). Furthermore, the signal (or information) is not limited to being notified by a downlink control signal; it may also be predefined in a specification (or standard) or pre-set in the base station and terminal.

[0224] In this disclosure, the uplink control signal (or uplink control information) associated with an embodiment of this disclosure may be, for example, a signal (or information) transmitted in the physical layer PUCCH, or a signal (or information) transmitted in the higher layer MAC CE or RRC. Furthermore, the signal (or information) is not limited to being notified by the uplink control signal; it may also be predefined in a specification (or standard) or pre-set in the base station and terminal. Additionally, the uplink control signal may be replaced, for example, with uplink control information (UCI), first-stage sidelink control information (SCI), or second-stage SCI.

[0225] (Base station)

[0226] In one embodiment of this disclosure, the base station can be a Transmission Reception Point (TRP), cluster head, access point, Remote Radio Head (RRH), eNodeB (eNB), gNodeB (gNB), Base Station (BS), Base Transceiver Station (BTS), host, gateway, etc. Additionally, in sidelink communication, the functions of the base station can also be performed by the terminal. Instead of a base station, it can also be a relay device for communication between a high-level relay node and the terminal. Furthermore, it can also be a roadside device.

[0227] (Uplink / Downlink / Sidelink)

[0228] An embodiment of this disclosure can be applied, for example, to any link in the uplink, downlink, or sidelink. For instance, an embodiment of this disclosure can be applied to the Physical Uplink Shared Channel (PUSCH), Physical Uplink Control Channel (PUCCH), Physical Random Access Channel (PRACH) of the uplink; the Physical Downlink Shared Channel (PDSCH), Physical Downlink Shared Channel (PDSCH), Physical Broadcast Channel (PBCH) of the downlink; or the Physical Sidelink Shared Channel (PSSCH), Physical Sidelink Control Channel (PSCCH), and Physical Sidelink Broadcast Channel (PSBCH) of the sidelink.

[0229] It should be noted that PDCCH, PDSCH, PUSCH, and PUCCH are examples of downlink control channels, downlink data channels, uplink data channels, and uplink control channels, respectively. Additionally, PSCCH and PSSCH are examples of sidelink control channels and sidelink data channels, respectively. Furthermore, PBCH and PSBCH are examples of broadcast channels, and PRACH is an example of a random access channel.

[0230] (Data Channel / Control Channel)

[0231] An embodiment of this disclosure can be applied, for example, to any channel in the data channel and the control channel. For example, the channel in an embodiment of this disclosure can also be replaced with one of the data channel's PDSCH, PUSCH, PSSCH, and the control channel's PDCCH, PUCCH, PBCH, PSCCH, PSBCH.

[0232] (Reference signal)

[0233] In one embodiment of this disclosure, the reference signal is, for example, a signal known to both the base station and the mobile station, and is sometimes referred to as "RS (Reference Signal)" or "pilot signal". The reference signal can also be one of the following: Demodulation Reference Signal (DMRS), Channel State Information-Reference Signal (CSI-RS), Tracking Reference Signal (TRS), Phase Tracking Reference Signal (PTRS), Cell-specific Reference Signal (CRS), or Sounding Reference Signal (SRS).

[0234] (Time interval)

[0235] In one embodiment of this disclosure, the unit of time resource is not limited to one or a combination of time slots and symbols. For example, it can be a frame, superframe, subframe, time slot, sub-time slot, micro-time slot, or symbol, Orthogonal Frequency Division Multiplexing Access (OFDM) symbol, Single Carrier-Frequency Division Multiple Access (SC-FDMA) symbol, or other time resource units. Furthermore, the number of symbols contained in one time slot is not limited to the number of symbols exemplified in the above embodiments, and can also be other numbers of symbols.

[0236] (frequency band)

[0237] One embodiment of this disclosure can be applied to any band domain, whether it is an authorized band domain or an unauthorized band domain.

[0238] (communication)

[0239] One embodiment of this disclosure can be applied to any communication in base station-terminal communication (Uu link communication), terminal-to-terminal communication (sidelink communication), and vehicle-to-everything (V2X) wireless communication technology. For example, the channel in one embodiment of this disclosure can be replaced with one of PSCCH, PSSCH, Physical Sidelink Feedback Channel (PSFCH), PSBCH, PDCCH, PUCCH, PDSCH, PUSCH, and PBCH.

[0240] Furthermore, one embodiment of this disclosure can be applied to any network, including terrestrial networks and non-terrestrial networks (NTNs) that use satellites or High Altitude Pseudo Satellites (HAPS). Additionally, one embodiment of this disclosure can also be applied to terrestrial networks with transmission delays greater than the symbol length or time slot length, such as networks with large cell sizes and ultra-wideband transmission networks.

[0241] (Antenna Port)

[0242] In one embodiment of this disclosure, an antenna port refers to a logical antenna (antenna group) composed of one or more physical antennas. For example, an antenna port may not necessarily refer to a single physical antenna; sometimes it refers to an array antenna composed of multiple antennas. For instance, instead of specifying how many physical antennas constitute an antenna port, it may be defined as the smallest unit that the terminal station can transmit a reference signal. Additionally, an antenna port is sometimes also defined as the smallest unit multiplied by a precoding vector.

[0243] <5G NR System Architecture and Protocol Stack>

[0244] To realize the next version of fifth-generation mobile phone technology (also known simply as "5G"), which includes the development of a new radio access technology (NR) operating in the frequency range up to 100 GHz, 3GPP is continuing its work. The first version of the 5G standard was completed at the end of 2017, thus enabling the transition to the trial production of terminals (e.g., smartphones) according to the 5G NR standard and commercial deployment.

[0245] For example, the overall system architecture envisions a gNB-RAN (Next Generation Radio Access Network). The gNB provides UE-side termination for the NG radio access user plane (SDAP (Service Data Adaptation Protocol) / PDCP (Packet Data Convergence Protocol) / RLC (Radio Link Control) / MAC / PHY (Physical Layer)) and control plane (RRC) protocols. gNBs are interconnected via the Xn interface. Additionally, gNBs are connected to the NGC (Next Generation Core) via the Next Generation (NG) interface, and more specifically, to the AMF (Access and Mobility Management Function) (e.g., a specific core entity implementing the AMF) via the NG-C interface, and to the UPF (User Plane Function) (e.g., a specific core entity implementing the UPF) via the NG-U interface. Figure 13 This refers to the NG-RAN architecture (e.g., refer to 3GPP TS 38.300 v15.6.0, section 4).

[0246] The user plane protocol stack for NR (e.g., see 3GPP TS 38.300, section 4.4.1) comprises the PDCP (Packet Data Convergence Protocol, see TS 38.300, section 6.4) sublayer, RLC (Radio Link Control, see TS 38.300, section 6.3) sublayer, and MAC (Media Access Control, see TS 38.300, section 6.2) sublayer, which terminates on the network side in the gNB. Additionally, a new Access Stratum (AS) sublayer (SDAP: Service Data Adaptation Protocol) has been incorporated into PDCP (e.g., see 3GPP TS 38.300, section 6.5). Furthermore, a control plane protocol stack is defined for NR (e.g., see TS 38.300, section 4.4.2). A summary of Layer 2 functionality is described in Section 6 of TS 38.300. The functions of the PDCP sublayer, RLC sublayer, and MAC sublayer are listed in Sections 6.4, 6.3, and 6.2 of TS 38.300, respectively. The functions of the RRC layer are listed in Section 7 of TS 38.300.

[0247] For example, the media access control layer handles the multiplexing of logical channels, scheduling of processing involving various parameter sets, and various functions associated with scheduling.

[0248] For example, the Physical Layer (PHY) is responsible for encoding, PHY HARQ (Physical Layer Hybrid Automatic Repeat Request) processing, modulation, multi-antenna processing, and mapping signals to appropriate physical time-frequency resources. Additionally, the Physical Layer handles the mapping of physical channels to transport channels. The Physical Layer provides services to the MAC Layer in the form of transport channels. A physical channel corresponds to a set of time-frequency resources used to transmit a specific transport channel; each transport channel is mapped to a corresponding physical channel. For example, in physical channels, uplink physical channels include PRACH (Physical Random Access Channel), PUSCH (Physical Uplink Shared Channel), and PUCCH (Physical Uplink Control Channel), while downlink physical channels include PDSCH (Physical Downlink Shared Channel), PDCCH (Physical Downlink Control Channel), and PBCH (Physical Broadcast Channel).

[0249] In NR use cases / extended scenarios, enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), and massive machine-type communications (mMTC) can be included, each with multiple requirements in terms of data rate, latency, and coverage. For example, eMBB is expected to support peak data rates approximately three times that of IMT-Advanced (20Gbps in downlink and 10Gbps in uplink) and effective (user-experienced) data rates. On the other hand, in the case of URLLC, ultra-low latency (0.5ms in both UL and DL for the user plane) and high reliability (within 1ms, 1-10) are expected. -5 This introduces more stringent requirements. Finally, in mMTC, a high connection density is preferably required (1,000,000 devices / km in urban environments). 2 ), wide coverage in harsh environments and extremely long battery life (15 years) for inexpensive devices.

[0250] Therefore, a set of OFDM parameters suitable for one use case (e.g., subcarrier spacing (SCS), OFDM symbol length, cyclic prefix (CP) length, number of symbols per scheduling interval) may be ineffective for other use cases. For example, in low-latency services, it is preferable to require a shorter symbol length than in mMTC services (therefore, a larger subcarrier spacing) and / or fewer symbols per scheduling interval (also known as "TTI"). Moreover, in extended scenarios with large channel delay spread, it is preferable to require a longer CP length than in scenarios with shorter delay spread. The subcarrier spacing can also be optimized depending on the situation to maintain the same CP overhead. NR supports more than one subcarrier spacing value. Correspondingly, subcarrier spacings of 15kHz, 30kHz, 60kHz... are currently considered. The symbol length Tu and the subcarrier spacing Δf are directly related according to the formula Δf = 1 / Tu. Similarly, the LTE system can use the term "resource element" to represent the smallest unit of resources consisting of a subcarrier of the length of one OFDM / SC-FDMA (Single-Carrier Frequency Division Multiple Access) symbol.

[0251] In the new 5G-NR wireless system, resource grids for subcarriers and OFDM symbols are defined in both the uplink and downlink for each parameter set and each carrier. Each element of the resource grid is called a "resource element," which is determined based on the frequency index in the frequency domain and the symbol position in the time domain (refer to 3GPP TS 38.211 v15.6.0).

[0252] <Functional Separation between NG-RAN and 5GC in 5G NR>

[0253] Figure 14 This indicates the functional separation between NG-RAN and 5GC. The logical node of NG-RAN is either gNB or ng-eNB. 5GC has logical nodes AMF, UPF, and SMF (Session Management Function).

[0254] For example, gNB and ng-eNB host the following main functions:

[0255] - Functions such as Radio Bearer Control, Radio Admission Control, Connection Mobility Control, and Radio Resource Management (RRM) that dynamically allocates (schedules) resources to the UE in both the uplink and downlink links;

[0256] - Data IP (Internet Protocol) header compression, encryption, and integrity protection;

[0257] - Selection of AMF when attaching a UE in situations where the route to the AMF cannot be determined based on the information provided by the UE;

[0258] - Routing to user plane data towards UPF;

[0259] - Routing of control plane information toward AMF;

[0260] - Setting and canceling connections;

[0261] - Scheduling and sending paging messages;

[0262] - The scheduling and transmission of system broadcast information (originating from AMF or Operation, Admission, and Maintenance functions (OAM));

[0263] - Setting up measurements and measurement reports for mobility and scheduling;

[0264] - Packet markings for transmission class in the uplink;

[0265] -Session management;

[0266] -Support for network slicing;

[0267] - QoS (Quality of Service) flow management and mapping to data radio bearers;

[0268] Support for UEs in RRC_INACTIVE (RRC inactive) state;

[0269] - NAS (Non-Access Stratum) message distribution function;

[0270] - Sharing of wireless access networks;

[0271] - Dual connectivity;

[0272] - Close collaboration between NR and E-UTRA (Evolved Universal Terrestrial Radio Access).

[0273] The Access and Mobility Management Function (AMF) administers the following main functions:

[0274] - Function to terminate Non-Access Stratum (NAS) signaling;

[0275] -Security of NAS signaling;

[0276] - Security controls at the access layer (AS);

[0277] - Core Network (CN) inter-node signaling for mobility between 3GPP access networks;

[0278] - The possibility of a UE reaching idle mode (including control and execution of paging retransmission);

[0279] -Management of the registered area;

[0280] - Support for intra-system mobility and inter-system mobility;

[0281] -Access authentication;

[0282] - Access licenses that include roaming permission checks;

[0283] - Mobility management controls (subscription and policies);

[0284] -Support for network slicing;

[0285] - Selection of Session Management Function (SMF).

[0286] In addition, the User Face Function (UPF) hosts the following main functions:

[0287] - Anchor points for intra-RAT (Radio Access Technology) mobility / inter-RAT (where applicable) mobility;

[0288] - External PDU (Protocol Data Unit) session points used for interconnection with data networks;

[0289] - Packet routing and forwarding;

[0290] - Enforcement of policy rules in group checks and user-facing aspects;

[0291] - Reports on business usage;

[0292] - Uplink classifier used to support routing of service flows toward the data network;

[0293] - Branching points used to support multi-homed PDU sessions;

[0294] - For user plane QoS processing (e.g., packet filtering, gating, UL / DL rate enforcement);

[0295] - Uplink service verification (SDF (Service Data Flow) mapping to QoS flow);

[0296] - Downlink packet buffering and downlink data notification triggering functions.

[0297] Finally, the Session Management Function (SMF) administers the following main functions:

[0298] -Session management;

[0299] - The allocation and management of UE IP addresses;

[0300] -Selection and control of UPF;

[0301] - A function for setting traffic steering in the User Plane Function (UPF) to direct traffic to the appropriate destination;

[0302] - Enforcing policies and QoS in the control section;

[0303] - Notification of downlink data.

[0304] <The process of setting up and resetting RRC connection>

[0305] Figure 15 This refers to several interactions between the UE, gNB, and AMF (5GC entity) when the UE in the NAS part transitions from RRC_IDLE (RRC idle) to RRC_CONNECTED (RRC connected) (refer to TS 38.300 v15.6.0).

[0306] RRC is a higher-level signaling (protocol) used for UE and gNB configuration. Through this transition, the AMF prepares UE context data (which may include, for example, PDU session context, security keys, UE radio capabilities, UE security capabilities, etc.) and sends it to the gNB along with an initial context setting request. Next, the gNB and UE activate AS security together. This is done by the gNB sending a Security Mode Command message to the UE, which responds with a Security Mode Complete message. Then, the gNB sends an RRC Reconfiguration message to the UE, and receives an RRC Reconfiguration Complete message from the UE for this message, thereby enabling the reconfiguration of Signaling Radio Bearer 2 (SRB2) and Data Radio Bearer (DRB). For signaling-only connections, since SRB2 and DRB are not configured, the steps related to RRC reconfiguration can be omitted. Finally, the gNB notifies the AMF that the configuration process is complete using the Initial Context Setup Reply.

[0307] Therefore, this disclosure provides an entity for a fifth-generation core network (5GC) (e.g., AMF, SMF, etc.), comprising: a control circuit that, upon operation, establishes a Next Generation (NG) connection with a gNodeB; and a transmission unit that, upon operation, sends an initial context setting message to the gNodeB via the NG connection to configure the signaling radio bearer between the gNodeB and the User Equipment (UE). Specifically, the gNodeB transmits Radio Resource Control (RRC) signaling containing an Information Element (IE) to the UE via the signaling radio bearer. The UE then performs uplink transmission or downlink reception based on the resource allocation settings.

[0308] <Application Scenarios of IMT after 2020>

[0309] Figure 16This section outlines several use cases for 5G NR. Within the 3rd Generation Partnership Project New Radio (3GPP NR), three use cases supporting a wide variety of services and applications, conceived through IMT-2020, have been studied. Planning for the first phase of specifications for enhanced mobile broadband (eMBB) has been completed. Current and future work, in addition to gradually expanding eMBB support, includes standardization for ultra-reliable and low-latency communications (URLLC) and massive machine-type communications (mMTC). Figure 16 Several examples illustrating conceptual application scenarios for IMT after 2020 (e.g., referring to ITU-R M.2083). Figure 2 ).

[0310] URLLC use cases have strict requirements related to performance aspects such as throughput, latency, and availability. URLLC is conceived as a key technology for enabling wireless control of future industrial production or manufacturing processes, remote medical surgery, automation of power transmission and distribution in smart grids, and traffic safety applications. Ultra-high reliability of URLLC is supported by defining technologies that meet the requirements set by TR38.913. In NR URLLC version 15, a crucial requirement is a target user plane latency of 0.5ms in the UL (uplink) and 0.5ms in the DL (downlink). For a single packet transmission, the overall requirement for URLLC is a block error rate (BLER) of 1E-5 for a 32-byte packet size with a user plane latency of 1ms.

[0311] Considering the physical layer, numerous methods are available to improve reliability. Current possibilities for reliability enhancement include defining additional CQI (Channel Quality Indicator) tables for URLLC, a more compact DCI format, and PDCCH iteration. However, as NR (a crucial prerequisite for NR URLLC) becomes more stable and is further developed, this scope can be expanded to achieve ultra-high reliability. Specific use cases for NR URLLC in version 15 include augmented reality / virtual reality (AR / VR), e-health, e-safety, and other critical applications.

[0312] Furthermore, the technical enhancements for NR URLLC aim to improve latency and reliability. Latency enhancements include configurable parameter sets, non-slot-based scheduling utilizing flexible mapping, unlicensed (already licensed) uplinks, slot-level repetition in the data channel, and pre-emption in the downlink. Pre-emption refers to stopping a transmission with allocated resources and using those resources for a later-requested transmission that requires lower latency / higher priority. Therefore, a permitted transmission is replaced by a subsequent transmission. Pre-emption can be applied regardless of the specific service type. For example, a transmission in service type A (URLLC) can be replaced by a transmission in service type B (eMBB, etc.). Reliability enhancements include a dedicated CQI / MCS table for a target BLER of 1E-5.

[0313] The use cases for mMTC (massive machine-type communications) are characterized by a large number of connected devices that transmit relatively small amounts of data that are not easily affected by latency. These devices require low cost and very long battery life. From NR's perspective, utilizing very narrow bandwidth segments is a solution to save UE power and extend its battery life.

[0314] As mentioned above, the potential for improved reliability in NR is further expanded. It is one of the essential conditions for all situations; for example, high or ultra-high reliability is a crucial requirement related to URLLC and mMTC. From both wireless and network perspectives, reliability can be improved through several mechanisms. Generally, there are two to three important areas that could potentially contribute to improved reliability. These areas include compact control channel information, data / control channel iteration, and diversity related to the frequency, time, and / or spatial domains. These areas can be universally used to improve reliability, independent of specific communication scenarios.

[0315] Regarding NR URLLC, further use cases with more stringent requirements are envisioned, such as factory automation, transportation, and power transmission. Strict requirements refer to high reliability (achieving 10...). -6 High reliability, high availability, packet size up to 256 bytes, and time synchronization up to several microseconds (μs) (capable of setting the value to 1 microsecond or several microseconds depending on the use case, frequency range, and short latency of about 0.5ms to 1ms (e.g., 0.5ms latency in the target user plane)).

[0316] Furthermore, from a physical layer perspective, there are several technical enhancements to NR URLLC. These enhancements include strengthening the PDCCH (Physical Downlink Control Channel) associated with compact DCI, PDCCH repetition, and increased PDCCH monitoring. Additionally, enhancements to UCI (Uplink Control Information) are related to enhanced HARQ (Hybrid Automatic Repeat Request) and CSI feedback. Furthermore, there may be enhancements to PUSCH and retransmission / repetition related to mini-slot-level frequency hopping. The term "mini-slot" refers to a transmission time interval (TTI) containing fewer symbols than a time slot (a time slot has 14 symbols).

[0317] <QoS Control>

[0318] 5G's QoS (Quality of Service) model is based on QoS flows, supporting both QoS flows that require guaranteed bit rate (GBR) and QoS flows that do not require guaranteed bit rate (non-GBR QoS flows). Therefore, at the NAS level, QoS flows represent the finest granular QoS classification within a PDU session. QoS flows are determined within a PDU session based on the QoS Flow ID (QFI) transmitted via the encapsulation header through the NG-U interface.

[0319] For each UE, 5GC establishes one or more PDU sessions. For each UE, in conjunction with the PDU session, for example, NG-RAN as described above... Figure 15 As explained, at least one Data Radio Bearer (DRB) is established. Additionally, DRBs can be subsequently configured in QoS flows added to this PDU session (when to configure this depends on the NG-RAN). The NG-RAN maps packets belonging to various PDU sessions to various DRBs. NAS-level packet filters in the UE and 5GC are used to associate UL and DL packets with QoS flows, while AS-level mapping rules in the UE and NG-RAN associate UL and DL QoS flows with DRBs.

[0320] Figure 17 This refers to the non-roaming reference architecture of 5G NR (refer to TS 23.501 v16.1.0, section 4.23). Application Function (AF) (e.g., hosting). Figure 16The external application server for the illustrated 5G service interacts with the 3GPP core network to provide services. For example, it may access a Network Exposure Function (NEF) to support applications that impact service routing, or it may interact with a policy framework (see Policy Control Function (PCF)) for policy control (e.g., QoS control). Based on operator deployment, operators deem trusted application functions capable of directly interacting with associated network functions. Application functions not permitted by the operator to directly access network functions interact with associated network functions via the NEF, using an open framework accessible to the outside world.

[0321] Figure 17 It also indicates further functional units of the 5G architecture, namely, the Network Slice Selection Function (NSSF), the Network Repository Function (NRF), Unified Data Management (UDM), the Authentication Server Function (AUSF), the Access and Mobility Management Function (AMF), the Session Management Function (SMF), and the Data Network (DN: Data Network, such as services provided by operators, internet access, or services provided by third parties). All or part of the core network's functions and application services can also be deployed and operate in a cloud computing environment.

[0322] Therefore, this disclosure provides an application server (e.g., an AF in a 5G architecture) comprising: a transmitting unit that, in order to establish a PDU session containing a radio bearer between a gNodeB and a UE corresponding to QoS requirements, sends, during operation, a request containing at least one of the QoS requirements for URLLC service, eMMB service, and mMTC service to at least one of the functions of 5GC (e.g., NEF, AMF, SMF, PCF, UPF, etc.); and a control circuit that, during operation, performs services using the established PDU session.

[0323] This disclosure can be implemented in software, hardware, or software in cooperation with hardware. The functional blocks used in the above embodiments are implemented partially or wholly as LSIs (Large Scale Integration), and the processes described in the above embodiments can also be controlled partially or wholly by a single LSI or a combination of LSIs. An LSI can be composed of individual chips, or it can be composed of a single chip containing some or all of the functional blocks. An LSI may also include data input and output. Depending on the degree of integration, an LSI may also be referred to as an "IC (Integrated Circuit)," "System LSI," "Super LSI," or "Ultra LSI."

[0324] The method of integrating the LSI is not limited to LSI; it can also be implemented using dedicated circuits, general-purpose processors, or special-purpose processors. Alternatively, it can utilize a programmable FPGA (Field Programmable Gate Array) manufactured using the LSI, or a reconfigurable processor that allows reconfiguration of the connections or settings of the circuit blocks within the LSI. This disclosure can also be implemented for digital or analog processing.

[0325] Furthermore, if advancements in semiconductor technology or the emergence of other derivative technologies lead to integrated circuit technologies that can replace LSIs, these technologies could also be used to integrate functional blocks. There are also possibilities for applications such as biotechnology.

[0326] This disclosure can be implemented in all kinds of devices, apparatuses, and systems with communication capabilities (collectively referred to as "communication devices"). A communication device may also include a wireless transceiver and processing / control circuitry. The wireless transceiver may also include a receiving unit and a transmitting unit, or perform the functions of these units. The wireless transceiver (transmitting unit, receiving unit) may also include an RF (Radio Frequency) module and one or more antennas. The RF module may also include an amplifier, an RF modulator / demodulator, or similar devices. Non-limiting examples of communication devices include: telephones (mobile phones, smartphones, etc.), tablet computers, personal computers (PCs) (laptops, desktops, laptops, etc.), cameras (digital cameras, digital camcorders, etc.), digital players (digital audio / video players, etc.), wearable devices (wearable cameras, smartwatches, tracking devices, etc.), game consoles, e-book readers, remote health / telemedicine (remote healthcare / medical prescription) devices, vehicles or transportation vehicles with communication capabilities (cars, airplanes, ships, etc.), and combinations of the various devices described above.

[0327] Communication devices are not limited to portable or movable devices, but also include all kinds of devices, equipment, and systems that cannot be carried or fixed. Examples include: smart home devices (home appliances, lighting equipment, smart meters or meters, control panels, etc.), vending machines, and all other "things" that can exist on the IoT (Internet of Things) network.

[0328] In addition to data communication via cellular systems, wireless LAN (Local Area Network) systems, and communication satellite systems, communication also includes data communication via a combination of these systems.

[0329] In addition, the communication device also includes devices such as controllers or sensors that are connected or linked to a communication device performing the communication functions described in this disclosure. For example, it includes a controller or sensor that generates control signals or data signals used by the communication device to perform the communication functions of the communication device.

[0330] In addition, the communication device includes infrastructure equipment that communicates with or controls the various devices described above (not limited to these), such as base stations, access points, and all other devices, equipment, and systems.

[0331] A terminal according to an embodiment of this disclosure includes: a receiving circuit that receives control information relating to at least one of a first stop timing of downlink communication in a first communication path before switching, a second stop timing of uplink communication in the first communication path, a first start timing of downlink communication in a second communication path after switching, and a second start timing of uplink communication in the second communication path; and a control circuit that controls resynchronization processing in the second communication path based on the control information.

[0332] In one embodiment of this disclosure, the control circuit initiates the resynchronization process based on at least one of the first start timing and the second start timing.

[0333] In one embodiment of this disclosure, the control circuit controls the uplink communication to not occur during a time period determined based on the second stop timing and the second start timing.

[0334] In one embodiment of this disclosure, the control circuit controls the uplink communication to not occur during a time period determined based on the second stop timing and the first start timing.

[0335] In one embodiment of this disclosure, the control circuit is controlled to not trigger processing related to wireless link failure (RLF) or beam failure (BF) within a time period determined based on the first stop timing and the first start timing.

[0336] In one embodiment of this disclosure, the control circuit is controlled to not trigger processing related to radio link failure (RLF) or beam failure (BF) within a time period determined based on the second stop timing and the first start timing.

[0337] In one embodiment of this disclosure, the control information includes information related to the first start timing, but does not include information related to the first stop timing, the second stop timing, and the second start timing. The control circuit controls the process such that, during the time period determined by the first start timing and the reception timing of information related to the notification of switching from the first communication path to the second communication path, the uplink communication is not performed, or the processing related to wireless link failure (RLF) or beam failure (BF) is not triggered.

[0338] In one embodiment of this disclosure, the control information includes information related to the first stop timing, but does not include information related to the second stop timing, the first start timing, and the second start timing. The control circuit controls the process in such a way that, within a time period determined by a timing decision synchronously established based on the first stop timing and the second communication path, the uplink communication is not performed, or the processing related to wireless link failure (RLF) or beam failure (BF) is not triggered.

[0339] In one embodiment of this disclosure, the control circuit t starts the resynchronization process at the same time as the first stop timing.

[0340] A base station according to an embodiment of this disclosure includes: a transmitting circuit that transmits control information relating to at least one of a first stop timing of downlink communication in a first communication path before handover, a second stop timing of uplink communication in the first communication path, a first start timing of downlink communication in a second communication path after handover, and a second start timing of uplink communication in the second communication path; and a control circuit that controls the resynchronization processing of terminals in the second communication path based on the control information.

[0341] In a communication method according to an embodiment of this disclosure, the terminal performs the following steps: receiving control information related to at least one of the first stop timing of downlink communication in the first communication path before the switch, the second stop timing of uplink communication in the first communication path, the first start timing of downlink communication in the second communication path after the switch, and the second start timing of uplink communication in the second communication path; and controlling the resynchronization process in the second communication path based on the control information.

[0342] In a communication method according to an embodiment of this disclosure, the base station performs the following steps: sending control information related to at least one of the following: a first stop timing of downlink communication in the first communication path before handover, a second stop timing of uplink communication in the first communication path, a first start timing of downlink communication in the second communication path after handover, and a second start timing of uplink communication in the second communication path; and controlling at least one of the downlink and uplink communications based on the control information.

[0343] The entire contents of the specification, drawings and abstract of the specification contained in Japanese Patent Application No. 2023-127752, filed on August 4, 2023, are incorporated herein by reference.

[0344] Industrial applicability

[0345] One aspect of this disclosure is useful for wireless communication systems.

[0346] Explanation of reference numerals in the attached figures

[0347] 100 base stations

[0348] Antennas 101 and 201

[0349] 102, 202 Wireless Receiving Unit

[0350] 103 Data Receiving and Processing Department

[0351] 104 Control Department

[0352] Data transmission and processing departments 105 and 206

[0353] Wireless Transmission Units 106 and 207

[0354] 200 terminals

[0355] 203 Data Receiving and Processing Department

[0356] 204 Control Department

[0357] 205 Timing Adjustment Department

Claims

1. A terminal, characterized by comprising: Possessing: a reception circuit that receives control information related to at least one of a first stop timing of downlink communication in a first communication path before handover, a second stop timing of uplink communication in the first communication path, a first start timing of downlink communication in a second communication path after handover, and a second start timing of uplink communication in the second communication path; and a control circuit that controls re-synchronization processing in the second communication path based on the control information.

2. The terminal according to claim 1, wherein the control circuit starts the re-synchronization processing based on at least one of the first start timing and the second start timing.

3. The terminal according to claim 1, wherein the control circuit controls so as not to perform the uplink communication for a period decided based on the second stop timing and the second start timing.

4. The terminal according to claim 1, wherein the control circuit controls so as not to perform the uplink communication for a period decided based on the second stop timing and the first start timing.

5. The terminal according to claim 1, wherein the control circuit controls so as not to trigger processing related to radio link failure (RLF) or beam failure (BF) for a period decided based on the first stop timing and the first start timing.

6. The terminal according to claim 1, wherein the control circuit controls so as not to trigger processing related to radio link failure (RLF) or beam failure (BF) for a period decided based on the second stop timing and the first start timing.

7. The terminal according to claim 1, wherein the control information includes information related to the first start timing, and does not include information related to the first stop timing, the second stop timing, and the second start timing, the control circuit controls so as not to perform the uplink communication or not to trigger processing related to radio link failure (RLF) or beam failure (BF) for a period decided based on a reception timing of information related to notification of switching from the first communication path to the second communication path, and the first start timing.

8. The terminal according to claim 1, wherein the control information includes information related to the first stop timing, and does not include information related to the second stop timing, the first start timing, and the second start timing, the control circuit controls so as not to perform the uplink communication or not to trigger processing related to radio link failure (RLF) or beam failure (BF) for a period decided based on the first stop timing and a timing of synchronization establishment in the second communication path.

9. The terminal according to claim 8, wherein the control circuit starts the re-synchronization processing based on the first stop timing.

10. A base station, characterized by, Possessing: a transmission circuit that transmits control information related to at least one of a first stop timing of downlink communication in a first communication path before handover, a second stop timing of uplink communication in the first communication path, a first start timing of downlink communication in a second communication path after handover, and a second start timing of uplink communication in the second communication path; and a control circuit that controls re-synchronization processing of the terminal in the second communication path based on the control information.

11. A communication method characterized by comprising the steps of: a terminal receiving control information related to at least one of a first stop timing of downlink communication in a first communication path before handover, a second stop timing of uplink communication in the first communication path, a first start timing of downlink communication in a second communication path after handover, and a second start timing of uplink communication in the second communication path; and controlling re-synchronization processing in the second communication path based on the control information.

12. A communication method characterized by comprising the steps of: a base station transmitting control information related to at least one of a first stop timing of downlink communication in a first communication path before handover, a second stop timing of uplink communication in the first communication path, a first start timing of downlink communication in a second communication path after handover, and a second start timing of uplink communication in the second communication path; and controlling at least one of downlink communication and uplink communication based on the control information. ​ ​ ​ ​

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