Base station, terminal, and communication method

Abstract

The objective of the present invention is to improve the efficiency of adjacent cell measurements in satellite communications. This base station is provided with: a control circuit that sets, for a terminal connected to a first cell, control information used for resynchronization with a second cell adjacent to the first cell; and a transmitting circuit that transmits the control information.

Description

Base station, terminal, and communication method

[0001] The present disclosure relates to a base station, a terminal, and a communication method.

[0002] In the standardization of 5G, new radio access technology (NR) has been specified by 3GPP, and the NR Release 15 (Rel.15) specification has been published.

[0003] 3GPP, TR 38.821, V16.2.0 “Solutions for NR to support non-terrestrial networks (NTN) (Release 16)”R2-2305937, “Satellite switching without PCI change”, InterDigital

[0004] However, there is room for further study on the method of controlling the measurement of reception quality of neighboring cells.

[0005] Non-limiting embodiments of the present disclosure contribute to providing a base station, a terminal, and a communication method that can appropriately control reception quality measurement of neighboring cells.

[0006] A base station according to one embodiment of the present disclosure includes a control circuit that sets control information used for resynchronization to a second cell adjacent to a first cell for a terminal connected to the first cell, and a transmission circuit that transmits the control information.

[0007] These comprehensive or specific aspects may be realized as a system, an apparatus, a method, an integrated circuit, a computer program, or a recording medium, or may be realized as any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium.

[0008] According to an embodiment of the present disclosure, it is possible to appropriately control the reception quality measurement of neighboring cells.

[0009] Further advantages and benefits of certain aspects of the present disclosure will become apparent from the specification and drawings. Such advantages and / or benefits may be provided by some of the embodiments and features described in the specification and drawings, respectively, but not necessarily all of them may be provided to obtain one or more identical features.

[0010] 1 is a diagram showing an example of satellite switching; 2 is a block diagram showing an example of the configuration of a part of a base station; 3 is a block diagram showing an example of the configuration of a terminal; 4 is a block diagram showing an example of the configuration of a base station; 5 is a block diagram showing an example of the configuration of a terminal; 6 is a sequence diagram showing an example of the operation of a base station and a terminal; 7 is a sequence diagram showing an example of the operation of a base station and a terminal; 8 is a diagram of an exemplary architecture of a 3GPP NR system; 9 is a schematic diagram showing functional separation between NG-RAN and 5GC; 10 is a sequence diagram of a procedure for setting up / reconfiguring an RRC (Radio Resource Control) connection; 11 is a schematic diagram showing usage scenarios of enhanced Mobile BroadBand (eMBB), massive Machine Type Communications (mMTC), and Ultra Reliable and Low Latency Communications (URLLC), and

[0011] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0012] [Non-Terrestrial Networks (NTNs)] NR Rel. 15 is specified as a radio access technology for terrestrial networks. Meanwhile, Release 17 (Rel. 17) supports non-terrestrial networks (NTNs), such as communications using satellites or high-altitude platform stations (HAPSs) (see, for example, Non-Patent Document 1). For Release 18 (Rel. 18), NTN extension technologies are being studied.

[0013] One of NTN's enhanced technologies is mobility enhancement technology such as handover and cell reselection. For example, in the case of non-geostationary satellites such as low-earth orbit satellites (LEO), the efficiency of satellite or feeder link switching is being considered. A feeder link is, for example, a wireless link between a terrestrial base station or gateway (GW) and a satellite.

[0014] For example, as shown in Fig. 1, a communication path switching method for a terminal is being studied, which changes a satellite or a feeder link without changing a cell ID (e.g., PCI: Physical Cell ID) when switching between satellites or feeder links (e.g., Non-Patent Document 2). This method does not require processes such as radio resource control (RRC) connection reestablishment or security update (e.g., mobility processes at Layer 3 (L3) level) like handover, and therefore makes it possible to switch between satellites or feeder links (hereinafter referred to as "satellite switching") through simple processes.

[0015] Here, when switching the satellite or feeder link used for communication (hereinafter referred to as "satellite switching"), the terminal (e.g., User Equipment (UE)) resynchronizes with a new satellite (the satellite after switching) to continue communication. It is being considered that the base station (e.g., gNB) will notify the terminal of the need for resynchronization (e.g., a "notification to re-acquire DL / UL synchronization" message). Furthermore, it is being considered to notify the terminal of the timing of stopping the old link and the timing of starting the new link as the timing of satellite switching.

[0016] Meanwhile, the terminal appropriately measures the reception quality of neighboring cells in preparation for handover in a communication state (e.g., RRC_CONNECTED state) and cell reselection in a non-communication state (e.g., RRC_IDLE state or RRC_INACTIVE state (hereinafter referred to as "RRC_IDLE / INACTIVE state")).

[0017] When measuring a neighboring cell, the terminal synchronizes with the synchronization signal of the neighboring cell and then measures the received power or the received quality (e.g., the Signal to Noise and Interference Ratio (SINR)) using a quality measurement signal (e.g., a Synchronization Signal Block (SSB) or a Channel State Information - Reference Signal (CSI-RS)). For example, if the frequency used by the neighboring cell is different from the frequency of the serving cell, the terminal switches the frequency to synchronize with and measure the neighboring cell. Here, as a terminal implementation for improving the efficiency of neighboring cell measurement, the terminal may hold information such as a cell ID (e.g., a Physical Cell Identification (PCI)), frequency, and cell detection timing, and when measuring the neighboring cell, it may synchronize with and measure the neighboring cell in a short time based on this information.

[0018] Here, when a satellite switchover occurs, the terminal receives a notification to prompt resynchronization with the serving cell. Meanwhile, the terminal cannot identify the status (e.g., the satellite switchover status) of neighboring cells (e.g., neighbor cells 1, 2, and 3 shown in FIG. 1 ), and the need for resynchronization with the neighboring cells is unclear. Furthermore, for example, if a satellite switchover does not occur in the serving cell but occurs in a neighboring cell, the timing (e.g., including the cell detection timing) changes without the terminal detecting the satellite switchover in the neighboring cell, making it difficult to measure the neighboring cell using timing information managed (or held) by the terminal. This may result in a deterioration in the measurement accuracy of the neighboring cell, or a longer time required for neighboring cell measurement, resulting in communication delays or increased power consumption.

[0019] A non-limiting embodiment of the present disclosure describes a method for improving the efficiency of neighbor cell measurements in satellite communications. For example, in a non-limiting embodiment of the present disclosure, a base station notifies information related to a satellite or feeder link change or switch of a neighbor cell (or neighbor cell resynchronization notification information), and a terminal performs at least neighbor cell resynchronization based on the notification information. Hereinafter, the notification information will be referred to as "neighbor cell switch information."

[0020] [Overview of Communication System] A communication system according to an embodiment of the present disclosure includes a base station 100 and a terminal 200.

[0021] Fig. 2 is a block diagram showing an example of the configuration of a portion of base station 100. In base station 100 shown in Fig. 2, a control unit (e.g., corresponding to a control circuit) sets control information used for resynchronization with a second cell adjacent to a first cell for a terminal 200 connected to a first cell (e.g., a serving cell). A transmission unit (e.g., a transmission circuit) transmits the control information.

[0022] Fig. 3 is a block diagram showing a configuration example of a portion of terminal 200. In terminal 200 shown in Fig. 3, a receiving unit (e.g., corresponding to a receiving circuit) receives control information used for resynchronization with a second cell adjacent to a first cell (e.g., a serving cell) to which the terminal is connected. A control unit (e.g., a control circuit) controls resynchronization with the second cell based on the control information.

[0023] (Embodiment 1) [Configuration of Base Station] Fig. 4 is a block diagram showing an example of the configuration of base station 100 according to this embodiment. Base station 100 includes, for example, antenna 101, radio receiving section 102, data reception processing section 103, control section 104, data transmission processing section 105, and radio transmitting section 106.

[0024] At least one of the data reception processing unit 103, the control unit 104, and the data transmission processing unit 105 shown in Fig. 4 may be included in, for example, the control unit shown in Fig. 2. Furthermore, at least one of the antenna 101 and the wireless transmission unit 106 shown in Fig. 4 may be included in, for example, the transmission unit shown in Fig. 2.

[0025] Radio receiving unit 102 performs analog reception processing and digital reception processing such as down-conversion, A / D conversion, and filtering on a signal received from terminal 200 via antenna 101, and outputs the processed signal to data reception processing unit 103. Radio receiving unit 102 also stops and starts reception according to instructions from control unit 104.

[0026] The signals received by the radio receiving unit 102 may include, for example, at least one of a Physical Uplink Shared Channel (PUSCH), a Physical Uplink Control Channel (PUCCH), a Physical Random Access Channel (PRACH), and a Sounding Reference Signal (SRS).

[0027] The data reception processing unit 103 performs, for example, channel estimation, demodulation processing, and decoding processing on the received signal input from the radio receiving unit 102 to obtain a data sequence (received data).

[0028] The control unit 104 generates, for example, system information (or broadcast information) such as a Master Information Block (MIB) or a System Information Block (SIB), and terminal-specific control information (for example, an RRC message). 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 radio receiving unit 102 to stop and start reception, and instructs the radio transmitting unit 106 to stop and start transmission.

[0029] The system information may include at least one of the following control information for NTN: information regarding the satellite's orbit or position (satellite ephemeris information), common TA parameters used for terminal timing correction (TA: Timing Advance), and epoch time (reference time for the satellite ephemeris information and common TA parameters).

[0030] The RRC message may include information related to satellite switching, such as resynchronization notification information and timing information. 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 switching and the start timing of downlink and uplink (e.g., transmission and reception) of the satellite link after switching (e.g., information related to the satellite switching timing). These may also be included in the system information.

[0031] Furthermore, the control unit 104 generates, for example, neighboring cell switching information. The neighboring cell switching information may be transmitted to the terminal 200 by, for example, an SIB or terminal individual control information. An example of the neighboring cell switching information will be described later.

[0032] The data transmission processing unit 105 performs encoding (e.g., Low Density Parity Check (LDPC) encoding) and modulation (e.g., QPSK, 16QAM) on the transmission data and the control information input from the control unit 104, and outputs the modulated signal to the radio transmission unit 106.

[0033] The radio transmitting unit 106 performs transmission processing such as D / A conversion, filtering, up-conversion, and amplification on the signal input from the data transmission processing unit 105, and transmits the processed radio signal from the antenna 101. The radio transmitting unit 106 also stops and starts transmission in accordance with instructions from the control unit 104.

[0034] [Configuration of Terminal] Next, an example of the configuration of the terminal 200 will be described.

[0035] 5 is a block diagram showing an example of the configuration of terminal 200 according to this embodiment. Terminal 200 includes, for example, antenna 201, radio receiving section 202, data reception processing section 203, control section 204, timing adjustment section 205, neighboring cell management section 206, data transmission processing section 207, and radio transmitting section 208.

[0036] At least one of the data reception processing unit 203, the control unit 204, the timing adjustment unit 205, the neighboring cell management unit 206, and the data transmission processing unit 207 shown in Fig. 5 may be included in, for example, the control unit shown in Fig. 3. Furthermore, at least one of the antenna 201 and the radio receiving unit 202 shown in Fig. 5 may be included in, for example, the receiving unit shown in Fig. 3.

[0037] The radio receiving unit 202 performs analog receiving processing and digital receiving processing, such as down-conversion, A / D conversion, and filtering, on a downlink signal received from the base station 100 via the antenna 201, and outputs the processed signal to the data receiving processing unit 203. The radio receiving unit 202 also outputs information regarding the reception timing of a signal for timing synchronization, such as a synchronization signal (e.g., SSB: Synchronization Signal Block) included in the received signal, to the timing adjusting unit 205. The radio receiving unit 202 also performs resynchronization processing (e.g., re-synchronization or re-acquirement of synchronization) with the base station 100 in accordance with instructions from the control unit 204. The radio receiving unit 202 also performs synchronization processing with a neighboring cell for neighboring cell measurement and reception processing of signals to be measured for quality, such as SSB and CSI-RS, based on information input from the neighboring cell management unit 206 (e.g., the frequency, timing, or PCI of the neighboring cell).

[0038] The data reception processing unit 203 performs demodulation processing and decoding processing on the received signal (for example, a downlink signal such as SSB, PDCCH, or PDSCH) input from the radio reception unit 202, for example.

[0039] The control signal (e.g., PDCCH) may include, for example, resource allocation information for a downlink data signal (e.g., PDSCH), resource allocation information for an uplink data signal (e.g., PUSCH), or PUCCH resource allocation information used for HARQ-ACK transmission for the PDSCH. Furthermore, the control information (e.g., PDCCH) may include, for example, control information for paging. Furthermore, the downlink data signal (e.g., PDSCH) may include, for example, user data. Furthermore, the downlink data signal (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, a RACH response (e.g., Message 2 or Msg. 2), or information related to a TA command.

[0040] Furthermore, the data reception processing unit 203 performs reception processing of information related to satellite switching (e.g., resynchronization notification information, timing information, resynchronization notification information with an adjacent cell, etc.) included in, for example, broadcast information or RRC control information (e.g., an RRCReconfiguration message), and outputs the signal after reception processing to the control unit 204. Furthermore, the data reception processing unit 203 outputs, for example, information for the NTN (e.g., including at least one of satellite ephemeris, common TA parameters, and Epoch time) to the control unit 204.

[0041] The control unit 204 acquires position information (e.g., information such as latitude, longitude, and altitude) of the terminal 200 via a Global Navigation Satellite System (GNSS) or the like. The control unit 204 also calculates the orbit or position of the satellite based on information for the NTN (e.g., information on satellite ephemeris and epoch time) input from the data reception processing unit 203. The control unit 204 then calculates a timing adjustment value (e.g., a TA value) based on the position information of the terminal 200, the round-trip delay time between the terminal 200 and the satellite calculated using the information on the satellite's orbit or position, and the round-trip delay time between the terminal 200 and the satellite calculated using common TA parameters, and outputs the calculated timing adjustment value to the timing adjustment unit 205.

[0042] Furthermore, the control unit 204 outputs an instruction regarding resynchronization to the wireless receiving unit 202 based on the received information regarding satellite switching (e.g., resynchronization notification information and timing information) input from the data reception processing unit 203. Furthermore, the control unit 204 may determine the timing of stopping and restarting uplink transmission and the timing of stopping and restarting at least one of the processes of detecting and recovering from a Radio Link Failure (RLF) based on the timing information.

[0043] Furthermore, when neighboring cell switching information is input from the data reception processing unit, the control unit 204 notifies information related to the neighboring cell to the neighboring cell management unit 206. Furthermore, the control unit 204 outputs an instruction to resynchronize with the neighboring cell to the wireless receiving unit 202 based on the neighboring cell switching information.

[0044] Timing adjustment section 205 controls (e.g., adjusts) the transmission timing of a transmission signal (uplink signal) based on, for example, information relating to reception timing input from radio receiving section 202 and information relating to a timing adjustment value input from control section 204. Timing adjustment section 205 outputs information relating to timing adjustment to radio transmitting section 208.

[0045] The timing adjustment unit 205 may also store information about the reception timing of a signal for timing synchronization, such as a synchronization signal (e.g., SSB). The information about the reception timing may be used, for example, when receiving data in the radio receiving unit 202. The timing adjustment unit 205 may also store information about new timing when resynchronization is performed when switching satellites.

[0046] The timing adjustment unit 205 is not limited to adjusting the timing, but may also adjust the frequency.

[0047] The neighboring cell management unit 206 manages information about neighboring cells and neighboring cell measurement results using information from the control unit 204. For example, the neighboring cell management unit 206 holds information about the frequency, PCI, and timing of each neighboring cell, and indicates this information to the radio receiving unit when there is an opportunity to measure the neighboring cell.

[0048] The data transmission processing unit 207, for example, performs coding (e.g., LDPC coding) and modulation processing (e.g., QPSK and 16QAM) on the input transmission data, and outputs a signal (e.g., PUSCH, PUCCH, PRACH, or SRS) mapped to time and frequency resources to the radio transmission unit 208.

[0049] The radio transmitting unit 208 performs transmission processing such as D / A conversion, filtering, up-conversion, and amplification on the signal input from the data transmission processing unit 207, and transmits the radio signal after the transmission processing from the antenna 201. The radio transmitting unit 208 adjusts the timing of transmission based on the timing information input from the timing adjusting unit 205, for example.

[0050] [Example of Operation of Base Station and Terminal] Next, an example of operation of base station 100 and terminal 200 will be described.

[0051] The neighboring cell switching information is, for example, information for notifying a change (or that the change has occurred) in the timing of the neighboring cell.

[0052] The neighboring cell switching information may be, for example, information regarding whether or not the PCI of the neighboring cell will change (or whether or not it has changed), information regarding whether or not the timing of the neighboring cell will change (or whether or not it has changed), or information indicating a combination of whether or not the PCI will change and whether or not each of the timing of the neighboring cell will change (or whether or not it has changed).

[0053] For example, the neighbor cell switching information may be information notifying one of the following four cases: Case 1: No timing change, no PCI change Case 2: Timing change, no PCI change Case 3: No timing change, PCI change Case 4: Timing change, PCI change

[0054] The information on whether the timing of the neighboring cell will change corresponds to, for example, information on whether the satellite or feeder link of the neighboring cell will change (or be switched).

[0055] FIG. 6 is a sequence diagram showing an example of the operation of the base station 100 (gNB) and the terminal 200 (UE) during communication (e.g., RRC_CONNECTED state).

[0056] In FIG. 6, before switching between satellite or feeder links, base station 100 notifies terminal 200 of re-synchronization notification information (for example, notification to re-sync timing information) including timing information.

[0057] Furthermore, base station 100 notifies terminal 200 of the neighbor cell switching information (for example, neighbor cell information) described above.

[0058] Note that the neighbor cell switching information may be notified to terminal 200 together with information relating to resynchronization in the serving cell (for example, resynchronization notification information), or may be notified independently.

[0059] After the satellite or feeder link is switched, the terminal 200 resynchronizes with the serving cell (its own cell) based on the notified timing information. For example, the terminal 200 receives an SSB or a synchronization signal, performs at least one of timing synchronization and frequency synchronization (e.g., resynchronization), and performs random access processing. This completes resynchronization of the downlink and uplink.

[0060] Furthermore, terminal 200 performs a resynchronization process with the neighboring cell based on neighboring cell resynchronization information. Regarding the resynchronization with the neighboring cell, terminal 200 receives, for example, an SSB or a synchronization signal of the neighboring cell, performs at least one of timing synchronization and frequency synchronization, and holds synchronization information.

[0061] Terminal 200 may perform the resynchronization process with the neighboring cell immediately after the resynchronization process with the serving cell or immediately before measuring the neighboring cell.

[0062] In Case 1 of the neighboring cell switching information, terminal 200 does not need to perform resynchronization processing with the neighboring cell. In Case 2 of the neighboring cell switching information, terminal 200 may perform timing resynchronization assuming the same PCI (or without performing cell search). In Case 3 of the neighboring cell switching information, terminal 200 may perform cell search (search for PCI) assuming the same timing (or without performing timing resynchronization). In Case 4 of the neighboring cell switching information, terminal 200 may perform cell search including timing.

[0063] FIG. 7 is a sequence diagram showing an example of the operation of the base station 100 (gNB) and the terminal 200 (UE) that is not in communication (e.g., in RRC_IDLE / INACTIVE state).

[0064] Since a one-to-one link is not established between the terminal 200 in the RRC_IDLE / INACTIVE state and the base station 100, notification from the base station 100 is basically performed by broadcast information such as an SIB. As the type of SIB, for example, SIB3 (intra-frequency neighboring cell information) or SIB4 (inter-frequency neighboring cell information) may be used.

[0065] Before switching the satellite or feeder link, the base station 100 notifies (announces) the terminal 200 of the SI change.

[0066] Furthermore, base station 100 notifies terminal 200 of resynchronization notification information including the above-mentioned timing information and neighboring cell switching information by using the SIB of the neighboring cell.

[0067] The terminal 200 receives the SI change notification and receives the updated SIB.

[0068] After the notified timing of switching the satellite or feeder link, the terminal 200 performs a resynchronization process with the neighboring cell in accordance with the neighboring cell switching information. Note that the resynchronization process with the neighboring cell based on the neighboring cell switching information is the same as the process performed by the terminal 200 in the RRC_CONNECTED state described above.

[0069] An example of the operation of the base station 100 and the terminal 200 has been described above.

[0070] Note that the neighboring cell switching information may be, for example, information specific to each of a plurality of neighboring cells (or groups), or may be information common to a plurality of neighboring cells (all or groups). When the neighboring cell switching information is information specific to a neighboring cell, the terminal 200 can perform the minimum necessary resynchronization process for each neighboring cell. On the other hand, when the neighboring cell switching information is information common to a plurality of cells, the terminal 200 performs resynchronization process for a plurality of neighboring cells (managed by the terminal 200), thereby reducing notification overhead.

[0071] [Example of Notification Format] Next, an example of a notification format will be described.

[0072] <Notification Format Example 1> Neighbor cell switching information is notified together with resynchronization notification information when switching satellites for the serving cell.

[0073] For example, Notification to re-acquire DL / UL synchronization information for the serving cell including neighbor cell switch information may be notified in the RRC reconfiguration message.

[0074] For example, the following information may be notified in the Notification to re-acquire DL / UL synchronization: Notification to re-acquire DL / UL synchronization ::= SEQUENCE{ t-Service INTEGER (0..549755813887) t-Start INTEGER (0..549755813887) NeighborCellStatus ENUMERATED {satellite / feederlink changed, PCI changed}

[0075] Here, t-Service indicates information about the time (or timing) when the current link (satellite or feeder link) becomes invalid (or stops), and t-Start indicates information about the time (or timing) when the new link (satellite or feeder link) becomes valid (or starts).

[0076] Furthermore, NeighborCellStatus is neighbor cell switching information, and may indicate, for example, at least one of information indicating whether the satellite or feeder link of the neighbor cell will change and information indicating whether the PCI will change.

[0077] Here, as information common to multiple (e.g., all) neighboring cells, if at least one of the satellite or feeder link and PCI changes in one of the multiple neighboring cells, information indicating the change may be notified in NeighborCellStatus.

[0078] On the other hand, neighbor cell switching information may be included as individual information for each of multiple neighbor cells. In this case, the neighbor cell switching information (NeighborCellStatus) may be expressed, for example, as follows: In this example, individual neighbor cell resynchronization information is included in the "Measurement object ID (MeasObjectID)" that is the target of neighbor cell measurement set in terminal 200. NeighborCellStatusList ::= SEQUENCE (SIZE (1..maxNrofObjectId)) OF NeighborCellStatus NeighborCellStatus ENUMERATED {satellite / feederlink changed, PCI changed}

[0079] <Notification Format Example 2> For example, if the satellite or feeder link of a neighboring cell is different from the satellite or feeder link of the serving cell, when the satellite or feeder link of the neighboring cell is switched, the neighboring cell switching information may be notified to terminal 200 independently of the information for the serving cell.

[0080] For example, the format of the neighbor cell re-synchronization notification may be expressed as follows: Notification of neighbor cell re-synchronization Cell ID INTEGER (0..1024) t-Service INTEGER (0..549755813887) t-Start INTEGER (0..549755813887)

[0081] Here, Cell ID indicates the PCI of the neighboring cell, t-Service indicates information about the time (or timing) when the current link (satellite or feeder link) of the neighboring cell becomes invalid (or stops), and t-Start is information about the time (or timing) when the new link (satellite or feeder link) of the neighboring cell becomes valid (or starts).

[0082] For example, the notification of switching of the satellite or feeder link of the neighboring cell may include information on the cell ID (PCI or Cell ID) and information on the timing of switching the link of the neighboring cell (e.g., the stop (t-Service) of the current link U (or old link) and the start (t-Start) of the new link).

[0083] These pieces of information may exist for each neighboring cell. For example, the neighboring cell switching information may include one piece of timing information and multiple pieces of cell ID information.

[0084] Furthermore, for example, these pieces of information may be notified as information common to a plurality of (for example, all) neighboring cells. In this case, the neighboring cell switching information does not need to include cell ID information.

[0085] Furthermore, as timing information, the resynchronization notification of the serving cell includes information on the stop time of the current link (e.g., t-Service), while the resynchronization notification of the neighboring cell includes information on the start time of the new link (e.g., t-Start), and may not include information on the stop time of the current link. This is because, in the case of the serving cell, information on the stop time of the current link is used to determine RLF (Radio Link Failure) or stop uplink transmission, whereas in the case of the neighboring cell, it is sufficient to specify information on the timing of downlink resynchronization. For the same reason, even if information on the stop and start timings of the uplink and downlink are notified for the serving cell, the timing information of the downlink is notified for the neighboring cell, and the timing information of the uplink does not have to be notified.

[0086] The timing information may be expressed in absolute time such as UTC (Coordinated Universal Time), or may be expressed in timing based on the SFN (System Frame Number) or slot number of the serving cell, or may be expressed in timing based on the SFN or slot number of each neighboring cell.

[0087] Furthermore, the neighboring cell switching information may be notification information that only switches the satellite or feeder link of the neighboring cell, without including other information such as a cell ID or timing information. In this case, terminal 200 may resynchronize with all neighboring cells.

[0088] An example of the notification format has been described above.

[0089] In this embodiment, base station 100 sets neighboring cell switching information used for resynchronization with a cell neighboring the serving cell for terminal 200 connected to the serving cell, and transmits the neighboring cell switching information to terminal 200. Terminal 200 controls resynchronization with the neighboring cell based on the received neighboring cell switching information.

[0090] As a result, when the satellite or feeder link is switched, neighboring cell switching information is notified to the terminal 200, so that the terminal 200 can appropriately perform resynchronization processing for the neighboring cell. For example, the terminal 200 can prevent a deterioration in measurement accuracy of the neighboring cell or a communication delay or an increase in power consumption due to a longer measurement time for the neighboring cell, without detecting a timing change of the neighboring cell.

[0091] As a result, according to this embodiment, it is possible to improve the efficiency of adjacent cell measurements in satellite communications, and to appropriately control the reception quality measurements of adjacent cells.

[0092] Second Embodiment The configurations of base station 100 and terminal 200 according to this embodiment may be the same as those in the first embodiment, for example.

[0093] In this embodiment, a case will be described in which the base station 100 (or the network) notifies switching of the satellite or feeder link by paging information.

[0094] For example, when a satellite or feeder link switch occurs in any cell within a paging area, the base station 100 may transmit paging information including resynchronization notification information of the serving cell or the neighboring cell. When the received paging information includes the resynchronization notification information of the serving cell or the neighboring cell, the terminal 200 may perform resynchronization processing with the cell.

[0095] The operations of base station 100 and terminal 200 according to this embodiment that differ from those of the first embodiment will be described.

[0096] The base station 100 (e.g., the control unit 104) generates and transmits paging information including resynchronization notification information and timing information of at least one of the serving cell and neighboring cells (hereinafter referred to as the serving cell / neighboring cell) regarding the satellite switching timing. The paging information may be transmitted, for example, by a PDCCH in which CRC is scrambled by the P-RNTI, or by a PDSCH scheduled by a DCI in which CRC is scrambled by the P-RNTI.

[0097] The terminal 200 (e.g., the radio receiving unit 202 and the data reception processing unit 203) receives, for example, paging information contained in the PDCCH or PDSCH, and resynchronizes at least one of the serving cell and the neighboring cell based on the serving cell / neighboring cell resynchronization notification information and timing information regarding satellite switching contained in the paging information.

[0098] Next, an example of the operation of the base station 100 and the terminal 200 will be described.

[0099] In this embodiment, the operations are the same as those in the first embodiment except that resynchronization notification information and timing information of the serving cell / neighboring cell regarding satellite switching are included in the paging information.

[0100] An example of notification of paging information will be described below.

[0101] The first example is notification by DCI (or PDCCH).

[0102] For example, in DCI format 1_0 in which a CRC (Cyclic Redundancy Check) is scrambled by a P-RNTI (Paging-Radio Network Temporary Identifier), paging information is notified to terminal 200. For example, resynchronization notification information may be notified to terminal 200 using a "Short Messages field" in the paging information.

[0103] For example, a change in a satellite or feeder link may be notified using one state of the Short Messages field, or two states of the Short Messages field may be notified either when "a satellite or feeder link has been changed with a PCI change" or when "a satellite or feeder link has been changed without a PCI change."

[0104] Furthermore, for example, in the Short Messages field, resynchronization notification information of the serving cell may be notified to the terminal 200 in the RRC_CONNECTED state, and resynchronization notification information of a neighboring cell may be notified to the terminal 200 in the RRC_CONNECTED state. Furthermore, resynchronization notification information regarding a neighboring cell (for example, a cell within a paging area) may be notified to the terminal 200 in the RRC_IDLE / INACTIVE state.

[0105] The second example is notification via PDSCH.

[0106] For example, resynchronization notification information may be notified to terminal 200 by a PDSCH scheduled by DCI format 1_0 in which the CRC is scrambled by the P-RNTI. Alternatively, the resynchronization notification information may be notified as a paging channel (PCH). In this case, the number of bits available for notifying the resynchronization notification information increases, and therefore, resynchronization notification information including information such as timing information and a cell ID as described in the first embodiment may be notified.

[0107] In this manner, in this embodiment, base station 100 notifies terminal 200 of resynchronization notification information by means of paging information.

[0108] As a result, the resynchronization notification information is notified to terminal 200 by paging information. For this reason, for example, the resynchronization notification information is notified by receiving DCI (or PDCCH) or by receiving PDSCH scheduled by DCI in both the RRC_CONNECTED state and the RRC_IDLE / INACTIVE state, so notification can be made in a short time. Furthermore, by using paging information, it is possible to notify the resynchronization notification information in a common method regardless of the connection (or communication) state of terminal 200, and processing can be simplified. Furthermore, because paging information is data intended for multiple terminals, the overhead for notification can be reduced.

[0109] The embodiments of the present disclosure have been described above.

[0110] In the above-described embodiments, the base station 100 explicitly notifies the neighboring cell switching information, and the terminal 200 performs the neighboring cell resynchronization process upon receiving the neighboring cell switching information. However, the present invention is not limited to this. For example, the neighboring cell switching information may be implicitly notified by a resynchronization notification of the serving cell.

[0111] For example, when terminal 200 receives a resynchronization notification of the serving cell, terminal 200 may perform resynchronization with neighboring cells. Terminal 200 may perform resynchronization with all detected neighboring cells, or may perform resynchronization with one or more detected neighboring cells. This makes it possible to reduce the amount of notification information related to resynchronization with neighboring cells.

[0112] Furthermore, for example, when terminal 200 receives notification of a change in the PCI of the serving cell, terminal 200 may perform resynchronization with neighboring cells. Terminal 200 may perform resynchronization with all detected neighboring cells. In this case, since it is highly likely that the PCI of the neighboring cells has also changed in addition to the PCI of the serving cell, terminal 200 may perform a PCI search (cell search) process. Terminal 200 may also perform resynchronization and PCI search with respect to one or more detected neighboring cells.

[0113] Furthermore, in each of the above-described embodiments, whether or not to notify neighboring cell switching information may be notified from base station 100 to terminal 200 as configuration information.

[0114] Furthermore, in each of the above embodiments, the timing-related information notified to terminal 200 may be expressed as absolute time such as UTC (Coordinated Universal Time), or may be expressed as SFN (System Frame Number) or slot number. In terminal 200, timing is often managed by SFN or slot number, so using SFN or slot number simplifies timing management at the terminal.

[0115] Furthermore, in each of the above embodiments, terminal 200 performs resynchronization processing with the satellite after switching, but if the resynchronization processing is not completed within a predetermined time, it may determine that RLF has occurred and perform reconnection processing. Alternatively, terminal 200 may transition to RRC_IDLE and perform cell search and initial connection processing. The predetermined time may be managed by an internal timer of terminal 200, or a timer value notified by base station 100 may be used.

[0116] Furthermore, the notification information of resynchronization of the serving cell does not have to be explicitly notified. For example, the notification information of resynchronization of the serving cell may be implicitly notified by timing information. For example, when timing information is notified from base station 100 to terminal 200, terminal 200 performs resynchronization processing of the serving cell and / or neighbor cell based on the notified timing.

[0117] Furthermore, the timing information may be information common to terminals 200 in a cell, for example, information included in system information, or may be information that differs for each terminal 200 (information notified to each terminal individually). In the latter case, it is possible to avoid collisions or reduce congestion of PRACHs caused by many terminals 200 transmitting PRACHs within a short period of time.

[0118] Furthermore, at least one of satellite ephemeris information, common TA parameters, and epoch time related to the satellite after switching may be notified to terminal 200 in advance, or may be notified by SIB after switching. In the former case, terminal 200 can transmit an uplink signal before receiving a downlink signal, and resynchronization can be established in a short time. In the latter case, terminal 200 receives an SIB (e.g., SIB19 related to NTN) during resynchronization, and performs PRACH transmission after obtaining information such as satellite ephemeris information, common TA parameters, or epoch time.

[0119] Furthermore, the above-described embodiments are applicable to any of the embodiments, regardless of the configuration of the ground station device (ground gateway or ground station).

[0120] Furthermore, the operations and notification contents of each embodiment may be configurable in the network.

[0121] Furthermore, the above-described embodiments are applicable regardless of the state of the terminal 200. For example, the above-described embodiments are applicable to any of the states of RRC_CONNECTED, RRC_INACTIVE, and RRC_IDLE.

[0122] Furthermore, in each of the above embodiments, an example of operation when switching satellites has been described, but the present invention can also be applied to a case where a feeder link ground station (such as a ground gateway) is switched without switching satellites.

[0123] Furthermore, the above-described embodiments are not limited to switching between satellites or feeder links, but can also be applied to cases where there is some switching that changes the timing at which a signal arrives at a cell after being transmitted by base station 100.

[0124] The satellite before the switch may be called a source satellite or a serving satellite, and the satellite after the switch may be called a target satellite.

[0125] Although the above embodiments are primarily directed to NTN, they can also be applied to devices other than NTN. For example, they can be applied when a relay device for communication to the terminal 200 is changed.

[0126] Furthermore, each of the above embodiments can be applied to NTNs based on NR specifications as well as NTNs based on NB-IoT and MTC (LTE).

[0127] An embodiment of the present disclosure can be used for different types of satellite communications, such as low earth orbit (LEO), medium earth orbit (MEO), high elliptical orbit (HEO), or geostationary earth orbit (GEO), which are at different altitudes above the Earth's surface.

[0128] In each of the above-described embodiments, satellite ephemeris information, which is information related to satellite positions, may be reported by system information or may be stored in advance by terminal 200. Furthermore, satellite ephemeris information may be updated when communication is possible. Furthermore, terminal 200 may identify satellite positions using information other than satellite ephemeris information.

[0129] In addition, in each of the above-described embodiments, an example has been described in which GNSS such as GPS (for example, position detection using satellite signals) is used, but this is not limiting, and position detection may be performed using, for example, a terrestrial cellular base station, a Wi-Fi (registered trademark) signal or a Bluetooth (registered trademark) signal, an acceleration sensor, or a combination of these detection methods. Furthermore, altitude information may be obtained from a barometric pressure sensor, etc.

[0130] In each of the above-described embodiments, a cell may be an area defined by the received power of an SSB or a Channel State Information - Reference Signal (CSI-RS) transmitted by a base station (or a satellite), or may be an area defined by a geographical location. Also, the cell in each of the above-described embodiments may be replaced with a beam defined by an SSB.

[0131] In addition, the satellite ephemeris information and the common TA parameter information may be notified as "EpochTime" and "TAInfo", respectively, in the NTN-Config of SIB19, for example.

[0132] In addition, in each of the above-described embodiments, the base station may be read as a "network."

[0133] Furthermore, in each of the above-described embodiments, terminal 200 may measure reception quality using other signals such as CSI-RS instead of SSB signals.

[0134] Furthermore, in the above-described embodiment, uplink transmission from terminal 200 to base station 100 has been described, but one embodiment of the present disclosure is not limited to this and may also be applied to data in a downlink from base station 100 to terminal 200, or a link between terminals 200 (e.g., a sidelink).

[0135] Furthermore, an embodiment of the present disclosure may be applied regardless of the type of satellite, such as GEO, MEO, LEO, or HEO. Furthermore, an embodiment of the present disclosure may be applied to non-terrestrial communications, such as HAPS or drone base stations.

[0136] Furthermore, although the above-described embodiment has been described using an NTN environment (e.g., a satellite communication environment) as an example, the present disclosure is not limited thereto. The present disclosure may be applied to other communication environments (e.g., a terrestrial cellular environment of at least one of LTE and NR). For example, one embodiment of the present disclosure may be applied to terrestrial communications in an environment where the cell size is large and the propagation delay between the base station 100 and the terminal 200 is longer (e.g., above a threshold).

[0137] In addition, in the above-described embodiment, the form of satellite communication may be a configuration in which the base station functions are located on a satellite (e.g., a "regenerative satellite"), or a configuration in which the base station functions are located on the ground and a satellite relays communication between the base station and a terminal (e.g., a "transparent satellite"). For example, in one embodiment of the present disclosure, the downlink and the uplink may be links between a terminal and a satellite, or links via a satellite.

[0138] Furthermore, the method of notifying the control information from the base station 100 to the terminal 200 is not limited to the above-mentioned example, and may be notified (or reported, 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), or may be set in advance in the terminal 200, or may be specified in advance in a standard.

[0139] The base station may be referred to as a gNodeB or a gNB, and the terminal may be referred to as a UE.

[0140] Time resource units such as system frames and subframes may be replaced with slots, time slots, minislots, frames, subframes, and the like.

[0141] Furthermore, the notation "... section" in the above-described embodiments may be replaced with other notations such as "... circuitry," "... device," "... unit," or "... module."

[0142] (Supplementary Note) Information indicating whether the terminal 200 supports the functions, operations, or processes described in the above-described embodiments may be transmitted (or notified) from the terminal 200 to the base station 100, for example, as capability information or capability parameters of the terminal 200.

[0143] The capability information may include an information element (IE) that individually indicates whether or not the terminal 200 supports at least one of the functions, operations, or processes described in the above-described embodiments. Alternatively, the capability information may include an information element that indicates whether or not the terminal 200 supports a combination of any two or more of the functions, operations, or processes described in the above-described embodiments.

[0144] For example, the base station 100 may determine (or decide or assume) the functions, operations, or processes that the terminal 200 that transmitted the capability information supports (or does not support) based on the capability information received from the terminal 200. The base station 100 may perform operations, processes, or controls according to the determination result based on the capability information. For example, the base station 100 may control communications for the NTN based on the capability information received from the terminal 200.

[0145] Note that the fact that terminal 200 does not support some of the functions, operations, or processes described in the above-described embodiments may be interpreted as meaning that such some of the functions, operations, or processes are restricted in terminal 200. For example, information or a request regarding such restrictions may be notified to base station 100.

[0146] Information regarding the capabilities or limitations of terminal 200 may, for example, be defined in a standard, or may be implicitly notified to base station 100 in association with information known at base station 100 or information transmitted to base station 100.

[0147] (Control Signal) In the present disclosure, a downlink control signal (or downlink control information) related to an embodiment of the present disclosure may be, for example, a signal (or information) transmitted in a Physical Downlink Control Channel (PDCCH) of a physical layer, or a signal (or information) transmitted in a Medium Access Control Control Element (MAC CE) or Radio Resource Control (RRC) of a higher layer. Furthermore, the signal (or information) is not limited to being notified by a downlink control signal, but may be predefined in a specification (or standard) or preconfigured in a base station and a terminal.

[0148] In the present disclosure, an uplink control signal (or uplink control information) related to an embodiment of the present disclosure may be, for example, a signal (or information) transmitted in a PUCCH of a physical layer, or a signal (or information) transmitted in a MAC CE or RRC of a higher layer. Furthermore, the signal (or information) is not limited to being notified by an uplink control signal, but may be predefined in a specification (or standard) or preconfigured in a base station and a terminal. Furthermore, the uplink control signal may be replaced with, for example, uplink control information (UCI), 1st stage sidelink control information (SCI), or 2nd stage SCI.

[0149] (Base Station) In an embodiment of the present disclosure, the base station may be a Transmission Reception Point (TRP), a cluster head, an access point, a Remote Radio Head (RRH), an eNodeB (eNB), a gNodeB (gNB), a Base Station (BS), a Base Transceiver Station (BTS), a parent device, a gateway, or the like. In sidelink communication, a terminal may play the role of a base station. Instead of a base station, a relay device that relays communication between an upper node and a terminal may be used. Alternatively, a roadside unit may be used.

[0150] (Uplink / Downlink / Sidelink) An embodiment of the present disclosure may be applied to, for example, any of the uplink, downlink, and sidelink. For example, an embodiment of the present disclosure may be applied to a Physical Uplink Shared Channel (PUSCH), a Physical Uplink Control Channel (PUCCH), or a Physical Random Access Channel (PRACH) in the uplink, a Physical Downlink Shared Channel (PDSCH), a PDCCH, or a Physical Broadcast Channel (PBCH) in the downlink, or a Physical Sidelink Shared Channel (PSSCH), a Physical Sidelink Control Channel (PSCCH), or a Physical Sidelink Broadcast Channel (PSBCH) in the sidelink.

[0151] The PDCCH, PDSCH, PUSCH, and PUCCH are examples of a downlink control channel, a downlink data channel, an uplink data channel, and an uplink control channel, respectively. The PSCCH and PSSCH are examples of a sidelink control channel and a sidelink data channel. The PBCH and PSBCH are examples of a broadcast channel, and the PRACH is an example of a random access channel.

[0152] (Data Channel / Control Channel) An embodiment of the present disclosure may be applied to, for example, either a data channel or a control channel. For example, the channel in an embodiment of the present disclosure may be replaced with any of the data channels PDSCH, PUSCH, and PSSCH, or the control channels PDCCH, PUCCH, PBCH, PSCCH, and PSBCH.

[0153] (Reference Signal) In one embodiment of the present disclosure, a reference signal is, for example, a signal known by both a base station and a mobile station, and may also be called a Reference Signal (RS) or a pilot signal. The reference signal may be any of a Demodulation Reference Signal (DMRS), a Channel State Information - Reference Signal (CSI-RS), a Tracking Reference Signal (TRS), a Phase Tracking Reference Signal (PTRS), a Cell-specific Reference Signal (CRS), or a Sounding Reference Signal (SRS).

[0154] (Time Interval) In one embodiment of the present disclosure, the unit of time resource is not limited to one or a combination of slots and symbols, but may be, for example, a time resource unit such as a frame, a superframe, a subframe, a slot, a time slot, a subslot, a minislot, a symbol, an Orthogonal Frequency Division Multiplexing (OFDM) symbol, a Single Carrier-Frequency Division Multiple Access (SC-FDMA) symbol, or another time resource unit. Furthermore, the number of symbols included in one slot is not limited to the number of symbols exemplified in the above-mentioned embodiment, and may be another number of symbols.

[0155] (Frequency Band) An embodiment of the present disclosure may be applied to either a licensed band or an unlicensed band.

[0156] (Communication) An embodiment of the present disclosure may be applied to communication between a base station and a terminal (Uu link communication), communication between terminals (Sidelink communication), or Vehicle to Everything (V2X) communication. For example, the channel in an embodiment of the present disclosure may be replaced with any of PSCCH, PSSCH, Physical Sidelink Feedback Channel (PSFCH), PSBCH, PDCCH, PUCCH, PDSCH, PUSCH, or PBCH.

[0157] An embodiment of the present disclosure may be applied to a terrestrial network, a non-terrestrial network (NTN) using a satellite or a high altitude pseudo satellite (HAPS), or a terrestrial network in which transmission delay is large compared to the symbol length or slot length, such as a network with a large cell size or an ultra-wideband transmission network.

[0158] (Antenna Port) In one embodiment of the present disclosure, an antenna port refers to a logical antenna (antenna group) consisting of one or more physical antennas. For example, an antenna port does not necessarily refer to a single physical antenna, but may refer to an array antenna consisting of multiple antennas. For example, the number of physical antennas that an antenna port is composed of is not specified, and the antenna port may be specified as the smallest unit by which a terminal station can transmit a reference signal. Furthermore, an antenna port may also be specified as the smallest unit by which a weighting of a precoding vector is multiplied.

[0159] 5G NR System Architecture and Protocol Stack 3GPP continues work on the next release of fifth-generation cellular technology (also referred to simply as "5G"), which includes the development of new radio access technology (NR) operating in the frequency range up to 100 GHz. The first version of the 5G standard was completed at the end of 2017, allowing for the prototyping and commercial deployment of 5G NR-compliant devices (e.g., smartphones).

[0160] For example, the system architecture generally assumes a Next Generation - Radio Access Network (NG-RAN) comprising gNBs. The gNBs provide UE-side termination of the NG radio access user plane (SDAP / PDCP / RLC / MAC / PHY) and control plane (RRC) protocols. The gNBs are connected to each other via an Xn interface. The gNBs are also connected to a Next Generation Core (NGC) via a Next Generation (NG) interface, more specifically to an Access and Mobility Management Function (AMF) (e.g., a specific core entity performing AMF) via an NG-C interface, and to a User Plane Function (UPF) (e.g., a specific core entity performing UPF) via an NG-U interface. The NG-RAN architecture is shown in Figure 8 (see, for example, 3GPP TS 38.300 v15.6.0, section 4).

[0161] The NR user plane protocol stack (see, for example, 3GPP TS 38.300, section 4.4.1) includes a PDCP (Packet Data Convergence Protocol (see, for example, TS 38.300, section 6.4)) sublayer, a RLC (Radio Link Control (see, for example, TS 38.300, section 6.3)) sublayer, and a MAC (Medium Access Control (see, for example, TS 38.300, section 6.2)) sublayer, which are terminated on the network side in the gNB. A new access stratum (AS) sublayer (SDAP: Service Data Adaptation Protocol) has also been introduced above PDCP (see, for example, 3GPP TS 38.300, section 6.5). A control plane protocol stack has also been defined for the NR (see, for example, TS 38.300, section 4.4.2). An overview of Layer 2 functions is described in Section 6 of TS 38.300. The functions of the PDCP sublayer, RLC sublayer, and MAC sublayer are listed in clauses 6.4, 6.3, and 6.2 of TS 38.300, respectively. The functions of the RRC layer are listed in clause 7 of TS 38.300.

[0162] For example, the Medium-Access-Control layer handles logical channel multiplexing and scheduling and scheduling-related functions, including handling various numerologies.

[0163] For example, the physical layer (PHY) is responsible for coding, PHY HARQ processing, modulation, multi-antenna processing, and mapping of signals to appropriate physical time-frequency resources. The physical layer also handles mapping of transport channels to physical 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 for transmitting a specific transport channel, and each transport channel is mapped to a corresponding physical channel. For example, physical channels include the Physical Random Access Channel (PRACH), the Physical Uplink Shared Channel (PUSCH), and the Physical Uplink Control Channel (PUCCH) as uplink physical channels, and the Physical Downlink Shared Channel (PDSCH), the Physical Downlink Control Channel (PDCCH), and the Physical Broadcast Channel (PBCH) as downlink physical channels.

[0164] NR use cases / deployment scenarios may include enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), and massive machine-type communication (mMTC), which have diverse requirements in terms of data rate, latency, and coverage. For example, eMBB is expected to support peak data rates (20 Gbps in the downlink and 10 Gbps in the uplink) and effective (user-experienced) data rates that are approximately three times higher than those offered by IMT-Advanced. On the other hand, for URLLC, stricter requirements are placed on ultra-low latency (0.5 ms for user plane latency in both UL and DL) and high reliability (1-10 ms within 1 ms). －５Finally, mMTC preferably requires high connection density (1,000,000 devices / km in urban environments). ２ ), wide coverage in adverse environments, and extremely long battery life (15 years) for a low-cost device may be desired.

[0165] Therefore, OFDM numerology (e.g., subcarrier spacing, OFDM symbol length, cyclic prefix (CP) length, number of symbols per scheduling interval) suitable for one use case may not be valid for another use case. For example, low-latency services may preferably require a shorter symbol length (and therefore a larger subcarrier spacing) and / or fewer symbols per scheduling interval (also referred to as TTI) than mMTC services. Furthermore, deployment scenarios with large channel delay spreads may preferably require a longer CP length than scenarios with short delay spreads. The subcarrier spacing may be optimized accordingly to maintain similar CP overhead. NR may support one or more subcarrier spacing values. Correspondingly, subcarrier spacings of 15 kHz, 30 kHz, 60 kHz, etc. are currently considered. The symbol length Tu and subcarrier spacing Δf are directly related by the formula Δf = 1 / Tu. Similar to LTE systems, the term "resource element" can be used to mean the smallest resource unit consisting of one subcarrier for the length of one OFDM / SC-FDMA symbol.

[0166] In the new radio system 5G-NR, for each numerology and each carrier, a resource grid of subcarriers and OFDM symbols is defined for each uplink and downlink. Each element of the resource grid is called a resource element and is specified based on a frequency index in the frequency domain and a symbol position in the time domain (see 3GPP TS 38.211 v15.6.0).

[0167] <Functional Separation Between NG-RAN and 5GC in 5G NR> Figure 9 shows the functional separation between NG-RAN and 5GC. The logical node of NG-RAN is gNB or ng-eNB. 5GC has logical nodes AMF, UPF, and SMF.

[0168] For example, gNB and ng-eNB host the following main functions: - Radio Resource Management functions such as Radio Bearer Control, Radio Admission Control, Connection Mobility Control, dynamic allocation (scheduling) of resources to UEs in both uplink and downlink; - IP header compression, ciphering and integrity protection of data; - AMF selection at UE attach time if routing to the AMF cannot be determined from the information provided by the UE; - Routing of user plane data towards the UPF; - Routing of control plane information towards the AMF; - Connection setup and release; - Scheduling and transmission of paging messages; - Scheduling and transmission of system broadcast information (sourced from the AMF or Operation, Admission, Maintenance (OAM)); - Configuration of measurements and measurement reports for mobility and scheduling; - Transport level packet marking in the uplink; - Session management; Support for network slicing; - QoS flow management and mapping to data radio bearers; - Support for UEs in RRC_INACTIVE state; - NAS message delivery function; - Radio access network sharing; - Dual connectivity; - Close coordination between NR and E-UTRA.

[0169] The Access and Mobility Management Function (AMF) hosts the following main functions: - Termination of Non-Access Stratum (NAS) signaling; - Security of NAS signaling; - Security control of Access Stratum (AS); - Signaling between Core Network (CN) nodes for mobility between 3GPP access networks; - Reachability to idle mode UEs (including control and execution of paging retransmissions); - Registration area management; - Support for intra-system and inter-system mobility; - Access authentication; - Access authorization including checking of roaming rights; - Mobility management control (subscription and policy); - Support for network slicing; - Selection of Session Management Function (SMF).

[0170] Furthermore, the User Plane Function (UPF) hosts the following main functions: - anchor point for intra-RAT / inter-RAT mobility (if applicable); - external PDU (Protocol Data Unit) session point for interconnection with data networks; - packet routing and forwarding; - packet inspection and policy rule enforcement for the user plane part; - traffic usage reporting; - uplink classifier to support routing of traffic flows to the data network; - branching point to support multi-homed PDU sessions; - QoS processing for the user plane (e.g. packet filtering, gating, UL / DL rate enforcement); - uplink traffic validation (mapping of SDF to QoS flows); - downlink packet buffering and triggering of downlink data notifications.

[0171] Finally, the Session Management Function (SMF) hosts the following main functions: session management; allocation and management of IP addresses for UEs; selection and control of UPF; configuration of traffic steering in the User Plane Function (UPF) to route traffic to the appropriate destination; policy enforcement and QoS of the control part; downlink data notification.

[0172] <RRC connection setup and reconfiguration procedure> Figure 10 shows some of the interactions between the UE, gNB, and AMF (5GC entities) when the UE transitions from RRC_IDLE to RRC_CONNECTED in the NAS part (see TS 38.300 v15.6.0).

[0173] RRC is a higher layer signaling (protocol) used to configure the UE and gNB. With this transition, the AMF prepares UE context data (including, 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 SETUP REQUEST. The gNB then activates AS security together with the UE. This is done by the gNB sending a SecurityModeCommand message to the UE, and the UE responding with a SecurityModeComplete message to the gNB. The gNB then sends an RRCReconfiguration message to the UE, and upon receiving an RRCReconfigurationComplete from the UE, the gNB performs reconfiguration to set up Signaling Radio Bearer 2 (SRB2) and Data Radio Bearer (DRB). For signaling-only connections, the steps related to RRCReconfiguration are omitted because SRB2 and DRB are not set up. Finally, the gNB notifies the AMF that the setup procedure is complete with an INITIAL CONTEXT SETUP RESPONSE.

[0174] Accordingly, the present disclosure provides a 5th Generation Core (5GC) entity (e.g., AMF, SMF, etc.) that includes: a control circuit that, upon operation, establishes a Next Generation (NG) connection with a gNodeB; and a transmitter that, upon operation, transmits an initial context setup message to the gNodeB via the NG connection so that a signaling radio bearer between the gNodeB and a user equipment (UE) is set up. Specifically, the gNodeB transmits Radio Resource Control (RRC) signaling, including a resource allocation configuration information element (IE), to the UE via the signaling radio bearer. The UE then transmits in uplink or receives in downlink based on the resource allocation configuration.

[0175] <IMT Usage Scenarios Beyond 2020> Figure 11 shows some use cases for 5G NR. The 3rd Generation Partnership Project New Radio (3GPP NR) is considering three use cases envisioned by IMT-2020 to support a wide variety of services and applications. The first phase of specifications for enhanced mobile broadband (eMBB) has been completed. Current and future work includes standardization for ultra-reliable and low-latency communications (URLLC) and massive machine-type communications (mMTC), in addition to expanding support for eMBB. Figure 11 shows some examples of envisioned usage scenarios for IMT beyond 2020 (see, for example, ITU-R M.2083 Figure 2).

[0176] The URLLC use case has stringent performance requirements for throughput, latency, and availability. It is envisioned as one of the enabling technologies for future applications such as wireless control of industrial production or manufacturing processes, remote medical surgery, automated power transmission and distribution in smart grids, and road safety. URLLC's ultra-high reliability is supported by identifying technologies that meet the requirements set by TR 38.913. Key requirements for NR URLLC in Release 15 include a target user plane latency of 0.5 ms on the uplink (UL) and 0.5 ms on the downlink (DL). The overall URLLC requirement for a single packet transmission is a block error rate (BLER) of 1E-5 for a 32-byte packet size with a user plane latency of 1 ms.

[0177] From a physical layer perspective, reliability can be improved in many possible ways. Current room for reliability improvement includes defining a separate CQI table for URLLC, more compact DCI formats, PDCCH repetition, etc. However, this room can be expanded to achieve ultra-high reliability as NR (with respect to the key requirements of NR URLLC) becomes more stable and developed. Specific use cases for NR URLLC in Release 15 include Augmented Reality / Virtual Reality (AR / VR), e-health, e-safety, and mission-critical applications.

[0178] Additionally, the technology enhancements targeted by NR URLLC aim to improve latency and reliability. Technology enhancements for latency improvement include configurable numerology, non-slot-based scheduling with flexible mapping, grant-free (configured grant) uplink, slot-level repetition in the data channel, and preemption in the downlink. Preemption means that a transmission with already allocated resources is stopped and the already allocated resources are used for another transmission with a later requested lower latency / higher priority. Therefore, a previously allowed transmission is preempted by a later transmission. Preemption is applicable regardless of the specific service type. For example, a transmission of service type A (URLLC) may be preempted by a transmission of service type B (eMBB, etc.). Technology enhancements for reliability improvement include a dedicated CQI / MCS table for a target BLER of 1E-5.

[0179] The use case of mMTC (massive machine type communication) is characterized by a very large number of connected devices that typically transmit relatively small amounts of data that are not sensitive to delays. These devices are required to be low-cost and have very long battery life. From the NR perspective, utilizing very narrow bandwidth portions is one solution that saves power and extends battery life from the UE's perspective.

[0180] As mentioned above, the scope of reliability improvement in NR is expected to be broader. One of the key requirements for all cases, for example, URLLC and mMTC, is high or ultra-high reliability. Several mechanisms can improve reliability from a radio perspective and a network perspective. Generally, there are two to three key areas that can help improve reliability. These areas include compact control channel information, repetition of data channels / control channels, and diversity in the frequency, time, and / or spatial domains. These areas are generally applicable to reliability improvement regardless of the specific communication scenario.

[0181] For NR URLLC, further use cases with more stringent requirements are envisioned, such as factory automation, transportation, and power distribution. －６ level reliability), high availability, packet size up to 256 bytes, time synchronization up to a few μs (depending on the use case, the value can be 1 μs or a few μs depending on the frequency range and low latency in the order of 0.5 ms to 1 ms (e.g., targeted user plane latency of 0.5 ms)).

[0182] Furthermore, for NR URLLC, there may be several technical enhancements from the physical layer perspective. These technical enhancements include PDCCH (Physical Downlink Control Channel) enhancements for compact DCI, PDCCH repetition, and increased PDCCH monitoring. Also, UCI (Uplink Control Information) enhancements relate to enhanced Hybrid Automatic Repeat Request (HARQ) and CSI feedback enhancements. There may also be PUSCH enhancements related to minislot-level hopping and retransmission / repetition enhancements. The term "minislot" refers to a Transmission Time Interval (TTI) that contains fewer symbols than a slot (a slot comprises 14 symbols).

[0183] <QoS Control> The 5G Quality of Service (QoS) model is based on QoS flows and supports both QoS flows that require a guaranteed flow bit rate (Guaranteed Bit Rate QoS flows (GBR)) and QoS flows that do not require a guaranteed flow bit rate (non-GBR QoS flows). Thus, at the NAS level, a QoS flow is the finest granularity of QoS classification in a PDU session. A QoS flow is identified within a PDU session by a QoS Flow ID (QFI) carried in an encapsulation header over the NG-U interface.

[0184] For each UE, 5GC establishes one or more PDU sessions. For each UE, the NG-RAN establishes at least one Data Radio Bearer (DRB) for each PDU session, e.g., as shown above with reference to FIG. 10. Additional DRBs for the QoS flows of that PDU session can be configured later (when this is up to the NG-RAN). The NG-RAN maps packets belonging to different PDU sessions to different DRBs. NAS-level packet filters in the UE and 5GC 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.

[0185] Figure 12 shows the non-roaming reference architecture for 5G NR (see TS 23.501 v16.1.0, section 4.23). An Application Function (AF) (e.g., an external application server hosting 5G services, as illustrated in Figure 11) interacts with the 3GPP core network to provide services. For example, it may access a Network Exposure Function (NEF) to support applications that affect traffic routing, or interact with a policy framework for policy control (e.g., QoS control) (see Policy Control Function (PCF)). Based on operator deployment, Application Functions considered trusted by the operator can interact directly with the associated Network Functions. Application Functions not permitted by the operator to directly access Network Functions interact with the associated Network Functions using an external exposure framework via the NEF.

[0186] Figure 12 further illustrates further functional units of the 5G architecture, namely, Network Slice Selection Function (NSSF), Network Repository Function (NRF), Unified Data Management (UDM), Authentication Server Function (AUSF), Access and Mobility Management Function (AMF), Session Management Function (SMF), and Data Network (DN, e.g., operator-provided services, Internet access, or third-party services). All or part of the core network functions and application services may be deployed and run in a cloud computing environment.

[0187] Therefore, the present disclosure provides an application server (e.g., an AF in a 5G architecture) comprising: a transmitter that, in operation, sends a request including QoS requirements for at least one of a URLLC service, an eMMB service, and an mMTC service to at least one of 5GC functions (e.g., an NEF, an AMF, an SMF, a PCF, an UPF, etc.) to establish a PDU session including a radio bearer between a gNodeB and a UE according to the QoS requirements; and a control circuit that, in operation, performs a service using the established PDU session.

[0188] The present disclosure can be realized by software, hardware, or software in conjunction with hardware. Each functional block used in the description of the above embodiments may be partially or entirely realized as an LSI, which is an integrated circuit, and each process described in the above embodiments may be partially or entirely controlled by a single LSI or a combination of LSIs. The LSI may be composed of individual chips, or may be composed of a single chip that includes some or all of the functional blocks. The LSI may have data input and output. Depending on the degree of integration, the LSI may also be called an IC, system LSI, super LSI, or ultra LSI.

[0189] The integrated circuit method is not limited to LSI, and may be realized by a dedicated circuit, a general-purpose processor, or a dedicated processor. Also, a field programmable gate array (FPGA) that can be programmed after LSI manufacturing, or a reconfigurable processor that can reconfigure the connections and settings of circuit cells within the LSI, may be used. The present disclosure may be realized as digital processing or analog processing.

[0190] Furthermore, if an integrated circuit technology that can replace LSI emerges due to advances in semiconductor technology or other derivative technologies, it is natural that such technology may be used to integrate functional blocks. The application of biotechnology, etc. is also a possibility.

[0191] The present disclosure may be implemented in any type of apparatus, device, or system (collectively referred to as a communications apparatus) that has a communications function. The communications apparatus may include a radio transceiver and processing / control circuitry. The radio transceiver may include a receiver and a transmitter, or both functions. The radio transceiver (transmitter and receiver) may include a radio frequency (RF) module and one or more antennas. The RF module may include an amplifier, an RF modulator / demodulator, or the like. Non-limiting examples of communication devices include telephones (e.g., cell phones, smartphones), tablets, personal computers (PCs) (e.g., laptops, desktops, notebooks), cameras (e.g., digital still / video cameras), digital players (e.g., digital audio / video players), wearable devices (e.g., wearable cameras, smartwatches, tracking devices), game consoles, digital book readers, telehealth / telemedicine devices, communication-enabled vehicles or mobile transportation (e.g., cars, airplanes, ships), and combinations of the above devices.

[0192] The communication devices are not limited to portable or mobile devices, but also include any kind of non-portable or fixed equipment, devices, and systems, such as smart home devices (such as home appliances, lighting equipment, smart meters or measuring devices, control panels, etc.), vending machines, and any other "things" that may exist on an IoT (Internet of Things) network.

[0193] Communications include data communications via cellular systems, wireless LAN systems, communication satellite systems, and the like, as well as data communications via combinations of these.

[0194] A communications apparatus also includes devices such as controllers and sensors connected or coupled to a communications device that performs the communications functions described in this disclosure, such as controllers and sensors that generate control and data signals used by the communications device to perform the communications functions of the communications apparatus.

[0195] The communication apparatus also includes infrastructure facilities, such as base stations, access points, and any other apparatus, device, or system that communicates with or controls the various apparatuses listed above, but are not limited to these.

[0196] A base station according to one embodiment of the present disclosure includes a control circuit that sets control information used for resynchronization to a second cell adjacent to a first cell for a terminal connected to the first cell, and a transmission circuit that transmits the control information.

[0197] In one embodiment of the present disclosure, the control information includes information indicating whether the cell identity information of the second cell is to be changed.

[0198] In one embodiment of the present disclosure, the control information includes information indicating whether a satellite or a feeder link corresponding to the second cell is to be changed.

[0199] In one embodiment of the present disclosure, the control information includes information indicating a combination of whether the cell identification information of the second cell changes and whether the satellite or feeder link corresponding to the second cell changes.

[0200] In one embodiment of the present disclosure, the control information is information common to a plurality of the second cells.

[0201] In one embodiment of the present disclosure, the control information is information specific to the plurality of second cells.

[0202] In one embodiment of the present disclosure, the control information is notified to the terminal together with information regarding resynchronization in the first cell.

[0203] In one embodiment of the present disclosure, the control information is notified to the terminal by paging information.

[0204] In one embodiment of the present disclosure, it is possible to set whether or not to notify the terminal of the control information.

[0205] A terminal according to one embodiment of the present disclosure includes a receiving circuit that receives control information used for resynchronization to a second cell adjacent to a first cell to which the terminal is connected, and a control circuit that controls resynchronization to the second cell based on the control information.

[0206] In a communication method according to one embodiment of the present disclosure, a base station configures control information for a terminal connected to a first cell to be used for resynchronization with a second cell adjacent to the first cell, and transmits the control information.

[0207] In a communication method according to one embodiment of the present disclosure, a terminal receives control information used for resynchronization to a second cell adjacent to a first cell to which the terminal is connected, and controls resynchronization to the second cell based on the control information.

[0208] The disclosures of the specification, drawings and abstract contained in Japanese Patent Application No. 2023-127755, filed on August 4, 2023, are incorporated herein by reference in their entirety.

[0209] One aspect of the present disclosure is useful in wireless communication systems.

[0210] 100 Base station 101, 201 Antenna 102, 202 Radio receiving unit 103 Data reception processing unit 104 Control unit 105, 207 Data transmission processing unit 106, 208 Radio transmitting unit 200 Terminal 203 Data reception processing unit 204 Control unit 205 Timing adjustment unit 206 Adjacent cell management unit

Claims

1. A base station comprising: a control circuit that sets control information used for resynchronization to a second cell adjacent to a first cell for a terminal connected to the first cell; and a transmission circuit that transmits the control information.

2. The base station according to claim 1, wherein the control information includes information indicating whether or not cell identification information of the second cell is to be changed.

3. The base station according to claim 1, wherein the control information includes information indicating whether a satellite or a feeder link corresponding to the second cell is to be changed.

4. The base station according to claim 1, wherein the control information includes information indicating a combination of whether cell identification information of the second cell changes and whether a satellite or a feeder link corresponding to the second cell changes.

5. The base station according to claim 1, wherein the control information is information common to a plurality of the second cells.

6. The base station according to claim 1, wherein the control information is information specific to a plurality of the second cells.

7. The base station according to claim 1, wherein the control information is notified to the terminal together with information regarding resynchronization in the first cell.

8. The base station according to claim 1, wherein the control information is notified to the terminal by paging information.

9. The base station according to claim 1, wherein whether or not to notify the terminal of the control information is configurable.

10. A terminal comprising: a receiving circuit that receives control information used for resynchronization to a second cell adjacent to a first cell to which the terminal is connected; and a control circuit that controls resynchronization to the second cell based on the control information.

11. A communication method, comprising: a base station configuring control information used for resynchronization with a second cell adjacent to the first cell for a terminal connected to the first cell; and transmitting the control information.

12. A communication method, comprising: a terminal receiving control information used for resynchronization to a second cell adjacent to a first cell to which the terminal is connected; and controlling resynchronization to the second cell based on the control information.

Images