Terminal, wireless communication system, and wireless communication method

Abstract

This terminal receives a reference signal associated with height, and executes measurement using the reference signal associated with the height at which the terminal is located.

Description

Terminal, wireless communication system, and wireless communication method

[0001] The present disclosure relates to a terminal mounted on a small unmanned aerial vehicle, a wireless communication system, and a wireless communication method.

[0002] The 3rd Generation Partnership Project (3GPP: registered trademark) is developing specifications for the 5th generation mobile communication system (5G, also known as New Radio (NR) or Next Generation (NG)), and is also developing specifications for the next generation, known as Beyond 5G, 5G Evolution, or 6G.

[0003] For example, with regard to support for small unmanned aerial vehicles (UAVs: Uncrewed Aerial Vehicles), such as drones equipped with a wireless communication module similar to that of a terminal (User Equipment, UE), it has been agreed to apply a list of synchronization signal blocks (SSB (Synchronization Signal) / PBCH (Physical Broadcast CHannel) Block)) according to the altitude at which the UAV (UE) is located (Non-Patent Document 1).

[0004] Furthermore, with regard to Lower layer Triggered Mobility (LTM), which is a technology related to the mobility of terminals (User Equipment, UE) in layer 1 or layer 2, measurements using Channel State Information-Reference Signal (CSI-RS) are being studied (Non-Patent Document 2).

[0005] "Report of 3GPP TSG RAN WG2 meeting #122, Incheon, Korea", R2-2307001, 3GPP TSG-RAN WG2 meeting #123, 3GPP, August 2023 "Moderator's summary on Rel-19 Mobility Enhancements", RP-232618, 3GPP TSG-RAN Meeting #101, 3GPP, September 2023

[0006] Supporting UAVs using a specific reference signal such as CSI-RS poses the following problem: Specifically, it is not possible to set reference signal resources according to the altitude of the UAV, i.e., the UE, or to perform measurements using those resources, which raises concerns that the state of the wireless channel and other factors may not be measured correctly.

[0007] Therefore, the following disclosure has been made in consideration of this situation, and aims to provide a terminal, a wireless communication system, and a wireless communication method that can set reference signal resources according to the UE altitude or perform measurements using those resources, even when supporting UAVs.

[0008] One aspect of the present disclosure is a terminal (UE200) that includes a receiving unit (control signal / reference signal processing unit 240) that receives a reference signal associated with an altitude, and a control unit (control unit 270) that performs measurements using the reference signal associated with the altitude at which the terminal is located.

[0009] One aspect of the present disclosure is a wireless communication system (wireless communication system 10) including a first radio base station and a second radio base station, wherein the first radio base station includes a control unit (control unit 270) that controls cell transition of a terminal (UE200) in accordance with mobility control by a lower layer, and a transmission unit (control signal / reference signal processing unit 240) that transmits altitude information indicating the altitude at which the terminal is located to the second radio base station, and the second radio base station includes a reception unit (control signal / reference signal processing unit 240) that receives the altitude information, and a control unit (control unit 270) that sets resources for a reference signal associated with the altitude based on the altitude information.

[0010] FIG. 1 is a diagram illustrating an overall schematic configuration of a wireless communication system 10. FIG. 2 is a diagram illustrating an example configuration of a radio frame, a subframe, and a slot used in the wireless communication system 10. FIG. 3 is a functional block diagram of a gNB 100 and a UE 200. FIG. 4 is a diagram illustrating an example configuration of a CSI-RS according to a first exemplary operation. FIG. 5 is a diagram illustrating an example sequence (part 1) of a measurement report according to the first exemplary operation. FIG. 6 is a diagram illustrating an example sequence (part 2) of a measurement report according to the first exemplary operation. FIG. 7 is a diagram illustrating an example sequence (part 1) of a CSI-RS configuration between a CU and a DU according to the second exemplary operation. FIG. 8 is a diagram illustrating an example sequence (part 2) of a CSI-RS configuration between a CU and a DU according to the second exemplary operation. FIG. 9 is a diagram illustrating an example sequence (part 1) of a CSI-RS configuration between a source CU and a candidate CU according to the second exemplary operation. FIG. 10 is a diagram illustrating an example sequence (part 2) of a CSI-RS configuration between a source CU and a candidate CU according to the second exemplary operation. Fig. 11 is a diagram illustrating an example of the hardware configuration of the gNB 100 and the UE 200. Fig. 12 is a diagram illustrating an example of the configuration of a vehicle 2001.

[0011] Hereinafter, embodiments will be described with reference to the drawings. Note that the same or similar reference numerals are used to designate the same functions or configurations, and descriptions thereof will be omitted as appropriate.

[0012] (1) Overall Schematic Configuration of Wireless Communication System Fig. 1 is an overall schematic configuration diagram of a wireless communication system 10 according to an embodiment. The wireless communication system 10 is a wireless communication system conforming to 5G New Radio (NR) and includes a Next Generation-Radio Access Network 20 (hereinafter, NG-RAN 20) and a terminal 200 (hereinafter, UE 200).

[0013] The wireless communication system 10 may be a wireless communication system conforming to a system called Beyond 5G, 5G Evolution, or 6G.

[0014] The NG-RAN 20 includes radio base station 100A (hereinafter, gNB100A) to radio base station 100D (hereinafter, gNB100D). The gNBs 100A to 100D have cells C1 to C4, respectively. Note that the specific configuration of the wireless communication system 10, including the number of gNBs and UEs, is not limited to the example shown in FIG. 1 .

[0015] The NG-RAN 20 actually includes a plurality of NG-RAN nodes, specifically, gNBs (or ng-eNBs), and is connected to a 5G-compliant core network (5GC, not shown). The NG-RAN 20 and the 5GC may be simply referred to as a "network."

[0016] The gNB100A to gNB100D are radio base stations conforming to 5G, and perform 5G radio communication with the UE 200. The gNB100A to gNB100D and the UE 200 are capable of supporting Massive MIMO (Multiple-Input Multiple-Output), which generates a more directional beam (BM) by controlling radio signals transmitted from multiple antenna elements, Carrier Aggregation (CA), which aggregates and uses multiple component carriers (CCs), and Dual Connectivity (DC), which simultaneously communicates on two or more transport blocks between the UE and each of two NG-RAN nodes.

[0017] The UE 200 may be a UE mounted on a small unmanned aerial vehicle (UAV: Uncrewed Aerial Vehicle or Unmanned Aerial Vehicle). The UE 200 mounted on a UAV or a UAV may be referred to as an NR drone. The UE 200 may also be referred to as a normal UE, a vehicle UE, an IAB (Integrated Access and Backhaul) UE (including an airborne IAB UE), a HAPS (High Altitude Platform Station) UE, an NTN (Non Terrestrial Network) UE, etc.

[0018] gNB100A to gNB100D (hereinafter referred to as gNB100 as appropriate) can transmit multiple beams with different transmission directions (which may also be simply referred to as directions, or radiation directions, or coverage) in space and time division. Note that gNB100 may transmit multiple beams simultaneously.

[0019] The wireless communication system 10 may also support multiple frequency ranges (FR) as follows:

[0020] ・FR1: 410 MHz to 7.125 GHz ・FR2-1: 24.25 GHz to 52.6 GHz FR1 may use a sub-carrier spacing (SCS) of 15, 30, or 60 kHz and a bandwidth (BW) of 5 to 100 MHz. FR2-1 is a higher frequency than FR1 and may use a sub-carrier spacing (SCS) of 60 or 120 kHz (including 240 kHz) and a bandwidth (BW) of 50 to 400 MHz.

[0021] Note that SCS may be interpreted as numerology, which is defined in 3GPP TS38.300 and corresponds to one subcarrier spacing in the frequency domain.

[0022] Furthermore, the wireless communication system 10 also supports a frequency band higher than the FR2-1 frequency band. Specifically, the wireless communication system 10 supports a frequency band exceeding 52.6 GHz up to 71 GHz. Such a high frequency band may be referred to as FR2-2.

[0023] When using bands above 52.6 GHz, Cyclic Prefix-Orthogonal Frequency Division Multiplexing (CP-OFDM) / Discrete Fourier Transform - Spread (DFT-S-OFDM) with larger Sub-Carrier Spacing (SCS) may be applied.

[0024] Additionally, as mentioned above, in high frequency bands such as FR2-2, increased inter-carrier phase noise becomes an issue, which may necessitate the application of a larger (wider) SCS or a single-carrier waveform.

[0025] The larger the SCS, the shorter the symbol / cyclic prefix (CP) period and slot period (assuming a 14 symbol / slot configuration is maintained). Figure 2 shows an example of the configuration of radio frames, subframes, and slots used in the wireless communication system 10.

[0026] If the 14-symbol / slot configuration is maintained, the larger (wider) the SCS, the shorter the symbol period (and slot period). The symbol period may also be called the symbol length, time direction, or time domain. The frequency direction may also be called the frequency domain, resource block, subcarrier, BWP (Bandwidth part), etc.

[0027] The frequency resources may include component carriers (CCs), subcarriers, resource blocks (RBs), resource block groups (RBGs), bandwidth parts (BWPs), etc. The time resources may include symbols, slots, minislots, subframes, radio frames, discontinuous reception (DRX) periods, etc.

[0028] The number of symbols constituting one slot does not necessarily have to be 14 (for example, 28 or 56 symbols). Also, the number of slots per subframe may differ depending on the SCS.

[0029] The wireless communication system 10 may use an SSB (SS / PBCH Block) that is configured from a synchronization signal (SS) and a downlink physical broadcast channel (PBCH).

[0030] SSBs are transmitted periodically from the network mainly to allow UE 200 to detect cell IDs and reception timings when starting communication. In NR, SSBs are also used to measure the reception quality of each cell. The SSB transmission periodicity may be specified as 5, 10, 20, 40, 80, 160 milliseconds, etc. Note that the initial access UE 200 may assume a transmission period of 20 milliseconds.

[0031] The UE 200 transmits a measurement report (hereinafter, referred to as a Measurement report) including reception qualities for cells including a serving cell and neighboring cells to the network. The procedure by which the UE 200 transmits the Measurement report may be referred to as Measurement reporting. The reception qualities for the cells may include reception qualities of beams from the cells, or may include reception qualities of cells based on beams from the cells.

[0032] Furthermore, in the wireless communication system 10, to support the UE 200 mounted on a UAV, the measurement target of reception quality may include information related to the altitude of the UE 200 (UAV). Specifically, a measObject, which is an information element (IE) that specifies the measurement target, may include a list of SSBs that depend on the UE's altitude (height dependent SSB list). Note that not only SSBs but also reference signals (RS) may be included as targets.

[0033] The UE 200 may perform measurement reporting periodically. The UE 200 may perform measurement reporting for each event. An entering condition for starting measurement reporting and a leaving condition for ending measurement reporting may be defined for each event. Existing events may include the following events (see 3GPP TS38.331):

[0034] (i) Event A1 Event A1 is an event in which the reception quality of the serving cell becomes better than a threshold. For example, the entering condition is Ms - Hys > Thresh, and the leaving condition is Ms + Hys < Thresh.

[0035] Here, Ms is the reception quality of the serving cell, Hys is a hysteresis parameter, and Thresh is a threshold value.

[0036] (ii) Event A2 Event A2 is an event in which the reception quality of the serving cell becomes worse than a threshold. For example, the entering condition is Ms + Hys < Thresh, and the leaving condition is Ms - Hys > Thresh.

[0037] Here, Ms is the reception quality of the serving cell, Hys is a hysteresis parameter, and Thresh is a threshold value.

[0038] (iii) Event A3 Event A3 is an event in which the reception quality of a neighboring cell is better than the reception quality of the serving cell by an offset. For example, the entering condition is Mn + Ofn + Ocn - Hys > Mp + Ofp + Ocp + Off, and the leaving condition is Mn + Ofn + Ocn + Hys < Mp + Ofp + Ocp + Off.

[0039] where Mn is the reception quality of the neighboring cell, Ofn is the offset specific to the measurement object, and Ocn is the offset specific to the cell. Mp is the reception quality of the serving cell, Ofp is the offset specific to the measurement object, and Ocp is the offset specific to the cell. Hys is the hysteresis parameter, and Off is the parameter used in Event A3.

[0040] (iv) Event A4 Event A4 is an event in which the reception quality of a neighboring cell becomes better than a threshold. For example, the entering condition is Mn + Ofn + Ocn - Hys > Thresh, and the leaving condition is Mn + Ofn + Ocn + Hys < Thresh.

[0041] where Mn is the reception quality of the neighboring cell, Ofn is an offset specific to the measurement object, Ocn is an offset specific to the cell, Hys is a hysteresis parameter, and Thresh is a threshold value.

[0042] (v) Event A5 Event A5 is an event in which the reception quality of the serving cell becomes worse than a threshold and the reception quality of a neighboring cell becomes better than a threshold. For example, the entering condition is Mp + Hys < Thresh1 and Mn + Ofn + Ocn - Hys > Thresh2, and the leaving condition is Mp - Hys > Thresh1 and Mn + Ofn + Ocn + Hys < Thresh2.

[0043] where Ms is the receiving quality of the serving cell, Hys is a hysteresis parameter, Thresh1 is a threshold, Mn is the receiving quality of the neighboring cell, Ofn is a measurement object-specific offset, and Ocn is a cell-specific offset, Hys is a hysteresis parameter, and Thresh2 is a threshold.

[0044] (vi) Event A6 Event A6 is an event in which the reception quality of a neighboring cell is better than the reception quality of a SCell (Secondary Cell) by an offset. For example, the entering condition is Mn + Ocn - Hys > Ms + Ocs + Off, and the leaving condition is Mn + Ocn + Hys < Ms + Ocs + Off.

[0045] In addition to the events described above, events related to different radio access technologies (RATs) (e.g., B1 (Inter RAT neighbour becomes better than threshold), B2 (Serving becomes worse than threshold1 and inter RAT neighbour becomes better than threshold2)) may be included.

[0046] Here, Mn is the reception quality of a neighboring cell, and Ocn is an offset specific to the cell. Ms is the reception quality of the SCell, and Ocs is an offset specific to the cell. Hys is a hysteresis parameter, and Off is a parameter used in Event A6.

[0047] Also, in the present embodiment, as described later, an event corresponding to the altitude at which the UE 200 is located (simply referred to as the altitude of the UE 200) may be set. The event may be a conditional event (CondEvent), and a plurality of thresholds corresponding to the altitude of the UE 200 (e.g., H1, H2, H1 < H2) may be applied.

[0048] In addition, the wireless communication system 10 may support conditional handover (CHO). In CHO, for the UE 200, a handover candidate cell and the execution conditions for handover (which may also be referred to as transition) to the candidate cell are set in advance.

[0049] As a result, the UE 200 can perform a handover to a target radio base station (which may also be referred to as a target cell) without waiting for a handover instruction from the network.

[0050] CHO may be interpreted as a handover that is executed by the UE 200 when one or more execution conditions are satisfied. The UE 200 may start evaluating the execution conditions when it receives the CHO configuration and may stop evaluating the execution conditions when a handover (legacy handover or conditional handover) is executed.

[0051] A candidate gNB or a potential target gNB may provide a CHO configuration to the UE 200. The source gNB may provide execution conditions, such as the timing for triggering the CHO, to the UE 200. The execution conditions may consist of one or more trigger conditions.

[0052] In addition, two or more different triggers, such as RSRP (Reference Signal Received Power), RSRQ (Reference Signal Received Quality), and SINR (Signal-to-Interference plus Noise power Ratio), may be set simultaneously to evaluate the CHO execution conditions of a candidate cell.

[0053] It should be noted that if CHO is configured in UE200 and UE200 receives another handover (HO) command from the gNB before the CHO execution condition is met, UE200 may trigger handover based on the received HO command and may not wait for the CHO condition to be met. In other words, the legacy HO configuration may take precedence over the CHO configuration (if configured).

[0054] In addition, in the wireless communication system 10, in addition to mobility management of the UE 200 at layer 3 (which may include, for example, a radio resource control layer (RRC)) (which may be called L3 mobility), mobility management at layer 1 / layer 2 (which may include, for example, a medium access control layer (MAC)) (which may be called LTM or L1 / L2 mobility) may be applied.

[0055] L3 Mobility may be interpreted as mobility control at the Radio Resource Control layer (RRC), while LTM may be interpreted as mobility control at the Physical layer (PHY), Medium Access Control layer (MAC), Radio Link Control layer (RLC), and Packet Data Convergence Protocol layer (PDCP).

[0056] (2) Functional Block Configuration of Wireless Communication System Next, a functional block configuration of the wireless communication system 10 will be described. Specifically, a functional block configuration of the UE 200 will be described. Fig. 3 is a functional block configuration diagram of the gNB 100 and the UE 200.

[0057] As shown in FIG. 3 , the UE 200 includes a radio signal transmitting / receiving unit 210, an amplifier unit 220, a modulation / demodulation unit 230, a control signal / reference signal processing unit 240, an encoding / decoding unit 250, a data transmitting / receiving unit 260, and a control unit 270.

[0058] It should be noted that Fig. 3 shows only the main functional blocks relevant to the description of the embodiment, and that the UE 200 (gNB 100) has other functional blocks (e.g., a power supply unit, etc.). Fig. 3 shows the functional block configuration of the UE 200, and for the hardware configuration, please refer to Fig. 11.

[0059] The radio signal transmitting and receiving unit 210 transmits and receives radio signals conforming to NR. The radio signal transmitting and receiving unit 210 can support Massive MIMO, which generates a more directional beam by controlling radio (RF) signals transmitted from multiple antenna elements, Carrier Aggregation (CA), which aggregates and uses multiple component carriers (CCs), and Dual Connectivity (DC), which simultaneously communicates between a UE and two NG-RAN nodes.

[0060] The amplifier unit 220 is configured by a PA (Power Amplifier) / LNA (Low Noise Amplifier), etc. The amplifier unit 220 amplifies the signal output from the modulation / demodulation unit 230 to a predetermined power level. The amplifier unit 220 also amplifies the RF signal output from the radio signal transmission / reception unit 210.

[0061] The modem unit 230 performs data modulation / demodulation, transmission power setting, resource block allocation, etc. for each predetermined communication destination (e.g., gNB 100). The modem unit 230 may apply Cyclic Prefix-Orthogonal Frequency Division Multiplexing (CP-OFDM) / Discrete Fourier Transform - Spread (DFT-S-OFDM). Furthermore, DFT-S-OFDM may be used not only for the uplink (UL) but also for the downlink (DL).

[0062] The control signal and reference signal processor 240 executes processing related to various control signals transmitted and received by the UE 200 and processing related to various reference signals transmitted and received by the UE 200 .

[0063] Specifically, the control signal / reference signal processing unit 240 receives various control signals, for example, control signals of a radio resource control layer (RRC), transmitted via a predetermined control channel from the gNB 100. In addition, the control signal / reference signal processing unit 240 transmits various control signals to the gNB 100 via a predetermined control channel.

[0064] The control signal and reference signal processor 240 performs processing using reference signals (RS) such as a Demodulation Reference Signal (DMRS) and a Tracking Reference Signal (TRS).

[0065] The DMRS is a reference signal (pilot signal) known between the base station and the terminal for estimating the fading channel used for data demodulation, while the TRS is a reference signal used to track time and frequency fluctuations in the downlink (DL).

[0066] In addition to DMRS and TRS, the reference signals may also include Channel State Information-Reference Signal (CSI-RS), Sounding Reference Signal (SRS), and Positioning Reference Signal (PRS) for position information.

[0067] The channels include a control channel and a data channel. The control channels may include a Physical Downlink Control Channel (PDCCH), a Physical Uplink Control Channel (PUCCH), a Random Access Channel (RACH, Downlink Control Information (DCI) including a Random Access Radio Network Temporary Identifier (RA-RNTI)), a Physical Broadcast Channel (PBCH), etc.

[0068] Furthermore, the data channel includes a physical downlink shared channel (PDSCH) and a physical uplink shared channel (PUSCH), etc. Data may refer to data transmitted via a data channel.

[0069] The control signal / reference signal processing unit 240 may transmit a measurement report in the lower layer (L1 / L2) to the network (gNB100).

[0070] Specifically, the control signal and reference signal processor 240 may transmit a Measurement report including the altitude of the UE 200. The altitude may be an absolute value of the height from a reference plane to the position of the UE 200 (UAV), or may be indicated by an index associated with an altitude range. The altitude may also be an average altitude within a predetermined time period, or may be the highest (or lowest) altitude. The control signal and reference signal processor 240 may transmit a Measurement report including an altitude index associated with the altitude of the UE 200 to the gNB 100.

[0071] The control signal and reference signal processor 240 may receive a reference signal associated with the altitude of the UE 200 (UAV). In this embodiment, the control signal and reference signal processor 240 may configure a receiver that receives a reference signal. Specifically, the control signal and reference signal processor 240 may receive a reference signal in which the position, number, or size of radio resources to be used varies depending on the altitude of the UE.

[0072] The target reference signals may not be particularly limited, but in this embodiment, at least the CSI-RS and the TRS may be targeted.

[0073] The control signal and reference signal processor 240 may transmit to the network a measurement report including information indicating the altitude at which the UE 200 is located. In this embodiment, the control signal and reference signal processor 240 may constitute a transmitter that transmits the measurement report.

[0074] Specifically, the control signal / reference signal processor 240 may transmit a measurement report including the current or past altitude of the UE 200 (UAV). The altitude may be an absolute value of the height from a reference plane to the position of the UE 200 (UAV), or may be indicated by an index associated with an altitude range. The altitude may also be an average altitude within a predetermined time period, or the highest (or lowest) altitude. Furthermore, the information may be configured by altitudes at multiple times in the past when the UE 200 (UAV) has passed. When multiple altitudes are included, time information (timestamps) may be added.

[0075] After transmitting the measurement report including the information indicating the altitude at which the UE 200 is located as described above, the control signal and reference signal processor 240 may receive, from the network, a reference signal associated with the altitude at which the UE 200 is located. The configuration of the reference signal may take into account the current or past altitude of the UE 200 (UAV).

[0076] Furthermore, control signal / reference signal processor 240 may transmit a measurement report based on the altitude at which UE 200 is located. As described above, the altitude may be an absolute value of the height from the reference plane to the position of UE 200 (UAV) or a range. Furthermore, multiple altitude thresholds (H1, H2, etc.) may be set, and measurement reports may be transmitted according to the relationship with the multiple altitude thresholds (specific examples will be described later).

[0077] If cell transition by LTM or CHO fails or a radio link failure (RLF) occurs, the control signal / reference signal processing unit 240 may transmit information including the altitude at which the UE 200 is located and the quality of the cell or beam (RSRP, RSRQ, SINR, etc.) to the network.

[0078] The network can configure measurement reporting to cause the UE to report measurement results for each SS / PBCH block. The network may configure measurement reporting to cause the UE to report measurement results for each SS / PBCH block(s), or may configure measurement reporting to cause the UE to report measurement results for each cell based on the SS / PBCH block(s). The network may configure measurement reporting to cause the UE to report measurement results for each CSI-RS resource, or may configure measurement reporting to cause the UE to report measurement results for each cell based on the CSI-RS resource.

[0079] The control signal and reference signal processor 240 may transmit capability information of the UE 200 to the network. For example, the control signal and reference signal processor 240 may transmit UE capability information relating to the trigger condition for a measurement report and the above-mentioned altitude to the gNB 100. In particular, in this embodiment, the UE capability information may include a range of altitudes at which the UE 200 can fly (or may potentially fly) (which may be a combination of the lowest and highest altitudes, or may be an average altitude).

[0080] The encoding / decoding unit 250 performs data division / concatenation and channel coding / decoding for each predetermined communication destination (gNB 100 or another gNB).

[0081] Specifically, the encoding / decoding unit 250 divides the data output from the data transmitting / receiving unit 260 into pieces of a predetermined size, performs channel coding on the divided data, decodes the data output from the modem unit 230, and concatenates the decoded data.

[0082] The data transmitter / receiver 260 transmits and receives Protocol Data Units (PDUs) and Service Data Units (SDUs). Specifically, the data transmitter / receiver 260 assembles and disassembles PDUs / SDUs in multiple layers (such as a Medium Access Control layer (MAC), a Radio Link Control layer (RLC), and a Packet Data Convergence Protocol layer (PDCP)). The data transmitter / receiver 260 also performs data error correction and retransmission control based on Hybrid Automatic Repeat Request (Hybrid ARQ).

[0083] The control unit 270 controls each functional block constituting the UE 200. In particular, in this embodiment, the control unit 270 can perform various controls regarding the CHO and LTM in consideration of the altitude of the UE 200.

[0084] The control unit 270 can execute a conditional handover (CHO) when an execution condition for the CHO is satisfied.

[0085] Furthermore, the control unit 270 may control cell transition (handover) of the UE 200 in accordance with mobility control (LTM) by the lower layer (L1 / L2).

[0086] In particular, the control unit 270 may determine whether the Execute condition is satisfied for the CHO based on a threshold value of the altitude at which the UE 200 is located and a quality threshold value of a candidate cell as a handover destination.

[0087] The control unit 270 may execute a cell transition (handover) by LTM when an execution condition based on an altitude threshold at which the UE 200 is located and a quality threshold of a candidate cell for handover by LTM is met.

[0088] Furthermore, the control unit 270 may perform measurements using a reference signal associated with the altitude at which the UE 200 is located. Specifically, the control unit 270 may perform measurements of the channel state, tracking of time and frequency fluctuations in DL, and the like, using a reference signal (e.g., CSI-RS or TRS) whose location, number, size, or the like of radio resources to be used varies depending on the altitude of the UE. Alternatively, the control unit 270 may use the reference signal to set a channel required for wireless communication with the network (gNB 100), and the like.

[0089] The control unit 270 may select one (or more) reference signals according to the altitude at which the UE 200 is located from among a plurality of reference signals associated with different altitudes (or ranges).

[0090] The gNB 100 may also have a function of supporting such an altitude-dependent reference signal. As described above, the wireless communication system 10 may include multiple gNBs 100 (radio base stations), and any one of the gNBs 100 (first radio base station) may include a control unit that controls cell transition (which may include handover) of the UE 200 in accordance with mobility control (LTM) by a lower layer (L1 / L2), and a transmission unit that transmits altitude information indicating the altitude at which the UE 200 is located to another gNB 100 (second radio base station).

[0091] Furthermore, the other gNB 100 (second radio base station) may include a receiver that receives the altitude information and a controller that sets a reference signal resource associated with the altitude based on the altitude information. The controller of the second radio base station may set a plurality of reference signal resources each associated with a different altitude.

[0092] The altitude information may be the same as the information indicating the altitude of the UE 200 included in the measurement report described above.

[0093] The first radio base station may be a source radio base station (cell) from which the transition is made, and the second radio base station may be a target (candidate) radio base station (cell) to which the transition is made. Furthermore, when the gNB 100 is configured with a CU (Central Unit, first device) and a DU (Distributed Unit, second device), the first radio base station may be the CU, and the second radio base station may be the DU. Alternatively, both the first radio base station and the second radio base station may be the CU or the DU.

[0094] (3) Operation of the Wireless Communication System Next, the operation of the wireless communication system 10 will be described. Specifically, the operation related to a measurement report that takes into account the altitude of the UE 200 (UAV) will be described. In particular, an example of the operation related to measurement using CSI-RS or TRS will be described below.

[0095] (3.1) Operation Example 1 When a UE mounted on a UAV, such as a drone, is at a high altitude, it is easier to capture the side lobes of the gNB antenna beam compared to a UE located on the ground, and the antenna beam with good quality may differ from that of a UE located on the ground.

[0096] In this operation example, CRS-RS or TRS may be set according to the altitude. Fig. 4 shows an example of setting CSI-RS according to operation example 1. Note that although Fig. 4 shows an example of CSI-RS, similar setting may also be applied to TRS.

[0097] As shown on the right side of Fig. 4, different CSI-RS resources may be associated with different altitudes (Height 1, 2). Also, as shown on the left side of Fig. 4, different CSI-RS resources may be associated with different altitude ranges (Height ranges 1, 2, 3). The altitude ranges may be divided into multiple stages, for example, every 10 m.

[0098] The number of associated CSI-RS resources may be one or more, and some CSI-RS resources may be associated in overlapping manner at different altitudes (ranges) (e.g., CSI-RS resource 10 in the figure).

[0099] Fig. 5 shows a sequence example (part 1) of a measurement report according to operation example 1. Fig. 6 shows a sequence example (part 2) of a measurement report according to operation example 1.

[0100] As shown in Figures 5 and 6, the gNB may transmit to the UE an RRCReconfiguration including the configuration of CSI-RS (and / or TRS, the same applies hereinafter) configured based on multiple altitudes (ranges) as described above. Note that, as shown in Figure 6, the gNB may configure a CSI-RS resource corresponding to the altitude based on information indicating the UE's altitude included in a Measurement report reported from the UE.

[0101] In addition, such a CSI-RS (TRS) may be linked to an SSB index included in an information element (Height dependent SSBToMeaureList) that specifies a list of SSBs that are highly dependent on the UE's altitude (height dependent SSB list).

[0102] A plurality of CSI-RS resource lists corresponding to altitudes and height ranges to which the lists apply may be set in advance. The UE may change the CSI-RS used for measurement depending on the height range that includes the altitude at which the UE is located.

[0103] In addition, hysteresis (Hyst) may be added to the height range. For example, when the UE is present within any height range, it may be expressed as follows:

[0104] heightMin (Minimum) - heightHyst) ≦ UE height ≦ (heightMax (Maximum) + heightHyst) Alternatively, full-spec CSI-RS resources corresponding to all height ranges may be configured in advance, and conditions for measuring some of these CSI-RS resources may be set according to the UE's altitude. For example, 64 CSI-RS resources may be configured, and the UE may use only a portion of them, i.e., 32, for measurement according to the height range.

[0105] According to this operation example, when applying CSI-RS based mobility, it is possible to change the CSI-RS resources to be used depending on the altitude. Therefore, even when the UE (UAV) is at a high altitude and it is easy to capture the side lobes of the gNB antenna beam, appropriate CSI-RS based mobility can be achieved.

[0106] (3.2) Operation Example 2 As described above, LTM may also be applied to a UE mounted on a UAV (UAV UE). In this operation example, an operation related to the configuration of CSI-RS (and / or TRS, the same applies hereinafter) when LTM is also applied to a UE mounted on a UAV will be described.

[0107] Fig. 7 shows an example (part 1) of a CSI-RS configuration sequence between a CU and a DU according to operation example 2. Fig. 8 shows an example (part 2) of a CSI-RS configuration sequence between a CU and a DU according to operation example 2.

[0108] 9 shows an example (part 1) of a sequence for configuring CSI-RS between a source CU and a candidate CU according to operation example 2. FIG. 10 shows an example (part 2) of a sequence for configuring CSI-RS between a source CU and a candidate CU according to operation example 2.

[0109] As shown in Figures 7 to 10, the source node (CU) may report altitude information of the UAV UE (UE altitude report) to the LTM candidate node (CU or DU).

[0110] The LTM candidate node (CU or DU) may configure resources for CSI-RS measurement based on the altitude (or height range) of the UAV UE. The resources may be configured on a candidate cell basis.

[0111] In the case of Intra-CU LTM, the candidate DU may transmit the resources for CSI-RS measurement configured based on the advanced information to the CU, and the CU may transmit the received resource information to the source DU.

[0112] In addition, in the case of Inter-CU LTM, the candidate CU may transmit the resource for CSI-RS measurement configured based on the altitude information to the source CU. The source CU may configure the resource for CSI-RS measurement for the UAV UE based on the altitude or height range of the UAV UE.

[0113] The Source CU or the Source DU may configure resources for CSI-RS measurement based on multiple altitudes (or height ranges), and the UAV UE may change the CSI-RS resource to be measured depending on the current altitude of the UE.

[0114] Alternatively, the Source CU or Source DU may configure the UE with CSI-RS measurement resources based on the altitude (or height range) and update the CSI-RS measurement resources to be measured according to the UE altitude using a MAC Control Element (CE).Furthermore, the Source CU or Source DU may activate or deactivate the CSI-RS measurement resources to be measured according to the UE altitude using a MAC Control Element (CE).

[0115] According to this operation example, even when LTM is applied to a UE installed on a UAV, CSI-RS (and TRS) resources can be set according to the altitude, making it possible to improve performance by measuring using appropriate CSI-RS resources.

[0116] (4) Other Embodiments Although the embodiments have been described above, it will be obvious to those skilled in the art that the present invention is not limited to the description of the embodiments, and that various modifications and improvements are possible.

[0117] For example, although the above-described embodiment assumes that the UE is mounted on a UAV, the UE does not necessarily have to be mounted on a UAV, i.e., similar operations may be applied when the UE is temporarily or permanently located in a position with good visibility.

[0118] Also, in the above description, configure, activate, update, indicate, enable, specify, and select may be interchangeable. Similarly, link, associate, correspond, and map may be interchangeable, and allocate, assign, monitor, and map may be interchangeable.

[0119] Furthermore, specific, dedicated, UE-specific, and UE-dedicated may be interchangeable. Similarly, common, shared, group-common, UE-common, and UE-shared may be interchangeable.

[0120] In the present disclosure, terms such as "precoding," "precoder," "weight (precoding weight)," "Quasi-Co-Location (QCL)," "Transmission Configuration Indication state (TCI state)," "spatial relation," "spatial domain filter," "transmit power," "phase rotation," "antenna port," "antenna port group," "layer," "number of layers," "rank," "resource," "resource set," "resource group," "beam," "beam width," "beam angle," "antenna," "antenna element," "panel," etc. may be used interchangeably.

[0121] The block diagram ( FIG. 3 ) used to explain the above-described embodiment shows functional blocks. These functional blocks (components) are realized by any combination of hardware and / or software. Furthermore, the method for realizing each functional block is not particularly limited. That is, each functional block may be realized using a single device that is physically or logically coupled, or may be realized using two or more physically or logically separated devices that are connected directly or indirectly (e.g., via wire, wireless, etc.) and these multiple devices. The functional block may be realized by combining the single device or multiple devices with software.

[0122] Functions include, but are not limited to, judgment, determination, judgment, calculation, computation, processing, derivation, investigation, search, confirmation, reception, transmission, output, access, resolution, selection, selection, establishment, comparison, assumption, expectation, consideration, broadcasting, notifying, communicating, forwarding, configuring, reconfiguring, allocating, mapping, and assignment. For example, a functional block (component) that performs transmission is called a transmitting unit or transmitter. As mentioned above, there are no particular limitations on how each is implemented.

[0123] Furthermore, the above-described gNB 100 and UE 200 (the devices) may function as a computer that performs processing of the wireless communication method of the present disclosure. Figure 11 is a diagram showing an example of the hardware configuration of the devices. As shown in Figure 11, the devices may be configured as a computer including a processor 1001, a memory 1002, a storage 1003, a communication device 1004, an input device 1005, an output device 1006, a bus 1007, etc.

[0124] In the following description, the term "apparatus" can be interpreted as a circuit, a device, a unit, etc. The hardware configuration of the apparatus may be configured to include one or more of the apparatuses shown in the drawings, or may be configured to exclude some of the apparatuses.

[0125] Each functional block of the device (see FIG. 3) is realized by any hardware element of the computer device or a combination of the hardware elements.

[0126] In addition, each function of the device is realized by loading specified software (programs) onto hardware such as processor 1001 and memory 1002, causing processor 1001 to perform calculations, control communication via communication device 1004, and control at least one of reading and writing data in memory 1002 and storage 1003.

[0127] The processor 1001 controls the entire computer by running, for example, an operating system, and may be configured as a central processing unit (CPU) including an interface with peripheral devices, a control unit, an arithmetic unit, and registers.

[0128] The processor 1001 also reads programs (program codes), software modules, data, etc. from at least one of the storage 1003 and the communication device 1004 into the memory 1002 and executes various processes in accordance with these. The programs used are those that cause a computer to execute at least some of the operations described in the above-described embodiments. Furthermore, the various processes described above may be executed by a single processor 1001, or may be executed simultaneously or sequentially by two or more processors 1001. The processor 1001 may be implemented by one or more chips. The programs may be transmitted from a network via a telecommunications line.

[0129] The memory 1002 is a computer-readable recording medium and may be configured by at least one of, for example, a read-only memory (ROM), an erasable programmable ROM (EPROM), an electrically erasable programmable ROM (EEPROM), a random access memory (RAM), etc. The memory 1002 may also be called a register, a cache, a main memory (primary storage device), etc. The memory 1002 may store a program (program code), a software module, etc., capable of executing a method according to an embodiment of the present disclosure.

[0130] Storage 1003 is a computer-readable recording medium, and may be, for example, at least one of an optical disk such as a Compact Disc ROM (CD-ROM), a hard disk drive, a flexible disk, a magneto-optical disk (e.g., a compact disk, a digital versatile disk, a Blu-ray disc), a smart card, a flash memory (e.g., a card, a stick, a key drive), a floppy disk, a magnetic strip, etc. Storage 1003 may also be referred to as an auxiliary storage device. The above-mentioned recording medium may be, for example, a database, a server, or other suitable medium including at least one of memory 1002 and storage 1003.

[0131] The communication device 1004 is hardware (transmission / reception device) for communicating between computers via at least one of a wired network and a wireless network, and is also called, for example, a network device, a network controller, a network card, or a communication module.

[0132] The communication device 1004 may be configured to include a high-frequency switch, a duplexer, a filter, a frequency synthesizer, etc. to realize, for example, at least one of Frequency Division Duplex (FDD) and Time Division Duplex (TDD).

[0133] The input device 1005 is an input device (e.g., a keyboard, a mouse, a microphone, a switch, a button, a sensor, etc.) that receives input from the outside. The output device 1006 is an output device (e.g., a display, a speaker, an LED lamp, etc.) that outputs to the outside. Note that the input device 1005 and the output device 1006 may be integrated into one device (e.g., a touch panel).

[0134] Furthermore, each device such as the processor 1001 and the memory 1002 is connected to a bus 1007 for communicating information. The bus 1007 may be configured using a single bus, or may be configured using different buses between each device.

[0135] Furthermore, the device may be configured to include hardware such as a microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a programmable logic device (PLD), or a field programmable gate array (FPGA), and some or all of the functional blocks may be realized by the hardware. For example, the processor 1001 may be implemented using at least one of these pieces of hardware.

[0136] Furthermore, the notification of information is not limited to the aspects / embodiments described in the present disclosure, and may be performed using other methods. For example, the notification of information may be performed by physical layer signaling (e.g., Downlink Control Information (DCI), Uplink Control Information (UCI)), higher layer signaling (e.g., RRC signaling, Medium Access Control (MAC) signaling, broadcast information (Master Information Block (MIB), System Information Block (SIB))), other signals, or a combination thereof. Furthermore, the RRC signaling may be referred to as an RRC message, and may be, for example, an RRC Connection Setup message, an RRC Connection Reconfiguration message, or the like.

[0137] Each aspect / embodiment described in the present disclosure may be applied to at least one of a system using Long Term Evolution (LTE), LTE-Advanced (LTE-A), SUPER 3G, IMT-Advanced, a 4th generation mobile communication system (4G), a 5th generation mobile communication system (5G), a 6th generation mobile communication system (6G), an xth generation mobile communication system (xG) (where x is, for example, an integer or a decimal), Future Radio Access (FRA), New Radio (NR), W-CDMA (registered trademark), GSM (registered trademark), CDMA2000, Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi (registered trademark)), IEEE 802.16 (WiMAX (registered trademark)), IEEE 802.20, Ultra-WideBand (UWB), Bluetooth (registered trademark), or other suitable system, and a next-generation system extended based on these. Furthermore, a combination of multiple systems (e.g., a combination of at least one of LTE and LTE-A with 5G) may also be applied.

[0138] The order of the procedures, sequences, flowcharts, etc. of each aspect / embodiment described in this disclosure may be changed unless it is consistent. For example, the methods described in this disclosure present elements of various steps using an example order, and are not limited to the particular order presented.

[0139] In the present disclosure, a specific operation described as being performed by a base station may also be performed by its upper node in some cases. In a network consisting of one or more network nodes having a base station, it is clear that various operations performed for communication with a terminal may be performed by at least one of the base station and another network node other than the base station (e.g., MME or S-GW, etc., but are not limited to these). Although the above example illustrates a case where there is one other network node other than the base station, a combination of multiple other network nodes (e.g., MME and S-GW) may also be used.

[0140] Information, signals (information, etc.) may be output from a higher layer (or a lower layer) to a lower layer (or a higher layer), or may be input and output via multiple network nodes.

[0141] The input and output information may be stored in a specific location (for example, a memory) or may be managed using a management table. The input and output information may be overwritten, updated, or added. The output information may be deleted. The input information may be transmitted to another device.

[0142] The determination may be made based on a value represented by one bit (0 or 1), a Boolean value (true or false), or a numerical comparison (e.g., comparison with a predetermined value).

[0143] The aspects / embodiments described in this disclosure may be used alone, in combination, or switched depending on the implementation. Notification of predetermined information (e.g., notification that "X is true") is not limited to explicit notification, but may be implicit (e.g., not notifying the predetermined information).

[0144] Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

[0145] Software, instructions, information, etc. may also be transmitted or received over a transmission medium. For example, if software is transmitted from a website, server, or other remote source using wired technologies (such as coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL)), and / or wireless technologies (such as infrared, microwave), then these wired and / or wireless technologies are included within the definition of transmission media.

[0146] The information, signals, etc. described in this disclosure may be represented using any of a variety of different technologies. For example, data, instructions, commands, information, signals, bits, symbols, chips, etc. that may be referred to throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or magnetic particles, optical fields or photons, or any combination thereof.

[0147] Note that terms described in this disclosure and terms necessary for understanding this disclosure may be replaced with terms having the same or similar meanings. For example, at least one of a channel and a symbol may be a signal (signaling). Furthermore, a signal may be a message. Furthermore, a component carrier (CC) may be called a carrier frequency, a cell, a frequency carrier, etc.

[0148] As used in this disclosure, the terms "system" and "network" are used interchangeably.

[0149] Furthermore, the information, parameters, etc. described in the present disclosure may be expressed using absolute values, relative values ​​from a predetermined value, or other corresponding information. For example, a radio resource may be indicated by an index.

[0150] The names used for the above-described parameters are not intended to be limiting in any way. Furthermore, the mathematical expressions using these parameters may differ from those explicitly disclosed in this disclosure. The various channels (e.g., PUCCH, PDCCH, etc.) and information elements may be identified by any suitable names, and therefore the various names assigned to these various channels and information elements are not intended to be limiting in any way.

[0151] In this disclosure, terms such as "base station (BS)," "radio base station," "fixed station," "NodeB," "eNodeB (eNB)," "gNodeB (gNB)," "access point," "transmission point," "reception point," "transmission / reception point," "cell," "sector," "cell group," "carrier," and "component carrier" may be used interchangeably. Base stations may also be referred to by terms such as macrocell, small cell, femtocell, and picocell.

[0152] A base station can accommodate one or more (e.g., three) cells (also called sectors). When a base station accommodates multiple cells, the overall coverage area of ​​the base station can be divided into multiple smaller areas, and each smaller area can be provided with communication services by a base station subsystem (e.g., a small indoor base station (Remote Radio Head: RRH)).

[0153] The terms "cell" or "sector" refer to part or all of the coverage area of ​​a base station and / or base station subsystem that provides communication services within that coverage area.

[0154] In the present disclosure, the base station transmitting information to a terminal may be interpreted as the base station instructing the terminal to control or operate based on the information.

[0155] In this disclosure, the terms "Mobile Station (MS)," "user terminal," "User Equipment (UE)," "terminal," etc. may be used interchangeably.

[0156] A mobile station may also be referred to by those skilled in the art as a subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, remote terminal, handset, user agent, mobile client, client, or some other suitable terminology.

[0157] At least one of the base station and the mobile station may be referred to as a transmitting device, a receiving device, a communication device, etc. At least one of the base station and the mobile station may be a device mounted on a mobile object, the mobile object itself, etc. The mobile object refers to a movable object, and may move at any speed. Naturally, this also includes cases where the mobile object is stationary. Examples of the mobile object include, but are not limited to, vehicles, transport vehicles, automobiles, motorcycles, bicycles, connected cars, excavators, bulldozers, wheel loaders, dump trucks, forklifts, trains, buses, handcars, rickshaws, ships and other watercraft, airplanes, rockets, satellites, drones (registered trademark), multicopters, quadcopters, balloons, and objects mounted thereon. The mobile object may also be a mobile object that moves autonomously based on an operational command. It may be a vehicle (e.g., a car, an airplane, etc.), an unmanned mobile object (e.g., a drone, an autonomous vehicle, etc.), or a robot (manned or unmanned). At least one of the base station and the mobile station may be a device that does not necessarily move during communication operations. For example, at least one of the base station and the mobile station may be an IoT (Internet of Things) device such as a sensor.

[0158] Furthermore, a base station in the present disclosure may be read as a mobile station (user terminal, the same applies hereinafter). For example, the aspects / embodiments of the present disclosure may be applied to a configuration in which communication between a base station and a mobile station is replaced with communication between multiple mobile stations (which may be called, for example, Device-to-Device (D2D) or Vehicle-to-Everything (V2X)). In this case, the mobile station may be configured to have the functions of a base station. Furthermore, terms such as "uplink" and "downlink" may be read as terms corresponding to terminal-to-terminal communication (for example, "side"). For example, terms such as an uplink channel and a downlink channel may be read as a side channel (or sidelink).

[0159] Similarly, a mobile station in the present disclosure may be interpreted as a base station, in which case the base station may have the functions of a mobile station.

[0160] A radio frame may be composed of one or more frames in the time domain. Each of the one or more frames in the time domain may be called a subframe. A subframe may further be composed of one or more slots in the time domain. A subframe may have a fixed time length (e.g., 1 ms) that is independent of numerology.

[0161] Numerology may be communication parameters that apply to the transmission and / or reception of a signal or channel, such as subcarrier spacing (SCS), bandwidth, symbol length, cyclic prefix length, transmission time interval (TTI), number of symbols per TTI, radio frame structure, specific filtering operations performed by the transceiver in the frequency domain, and specific windowing operations performed by the transceiver in the time domain.

[0162] A slot may consist of one or more symbols in the time domain (such as an Orthogonal Frequency Division Multiplexing (OFDM) symbol, a Single Carrier Frequency Division Multiple Access (SC-FDMA) symbol, etc.) A slot may be a numerology-based time unit.

[0163] A slot may include multiple minislots. Each minislot may consist of one or more symbols in the time domain. A minislot may also be called a subslot. A minislot may consist of fewer symbols than a slot. A PDSCH (or PUSCH) transmitted in a time unit larger than a minislot may be called PDSCH (or PUSCH) mapping type A. A PDSCH (or PUSCH) transmitted using a minislot may be called PDSCH (or PUSCH) mapping type B.

[0164] The radio frame, subframe, slot, minislot, and symbol all represent time units for transmitting signals, and may be referred to by other names corresponding to the radio frame, subframe, slot, minislot, and symbol.

[0165] For example, one subframe may be referred to as a transmission time interval (TTI), multiple consecutive subframes may be referred to as a TTI, or one slot or one minislot may be referred to as a TTI. That is, at least one of the subframe and the TTI may be a subframe (1 ms) in existing LTE, a period shorter than 1 ms (e.g., 1-13 symbols), or a period longer than 1 ms. Note that the unit representing the TTI may be called a slot, minislot, etc., instead of a subframe.

[0166] Here, TTI refers to, for example, the smallest time unit for scheduling in wireless communication. For example, in an LTE system, a base station schedules each user terminal to allocate radio resources (such as frequency bandwidth and transmission power that can be used by each user terminal) in TTI units. Note that the definition of TTI is not limited to this.

[0167] The TTI may be a transmission time unit for a channel-encoded data packet (transport block), a code block, a code word, etc., or may be a processing unit for scheduling, link adaptation, etc. When a TTI is given, the time interval (e.g., the number of symbols) to which a transport block, a code block, a code word, etc. is actually mapped may be shorter than the TTI.

[0168] In addition, when one slot or one minislot is called a TTI, one or more TTIs (i.e., one or more slots or one or more minislots) may be the minimum time unit for scheduling, and the number of slots (minislots) constituting the minimum time unit for scheduling may be controlled.

[0169] A TTI having a time length of 1 ms may be referred to as a regular TTI (TTI in LTE Rel. 8-12), normal TTI, long TTI, regular subframe, normal subframe, long subframe, slot, etc. A TTI shorter than a regular TTI may be referred to as a shortened TTI, short TTI, partial or fractional TTI, shortened subframe, short subframe, minislot, subslot, slot, etc.

[0170] In addition, a long TTI (e.g., a normal TTI, a subframe, etc.) may be interpreted as a TTI having a time length of more than 1 ms, and a short TTI (e.g., a shortened TTI, etc.) may be interpreted as a TTI having a TTI length shorter than the TTI length of a long TTI and equal to or greater than 1 ms.

[0171] A resource block (RB) is a resource allocation unit in the time domain and the frequency domain, and may include one or more consecutive subcarriers in the frequency domain. The number of subcarriers included in an RB may be the same regardless of numerology, for example, 12. The number of subcarriers included in an RB may be determined based on numerology.

[0172] The time domain of an RB may include one or more symbols and may have a length of one slot, one minislot, one subframe, or one TTI, each of which may consist of one or more resource blocks.

[0173] Note that one or more RBs may also be called a physical resource block (PRB), a sub-carrier group (SCG), a resource element group (REG), a PRB pair, an RB pair, etc.

[0174] Furthermore, a resource block may be composed of one or more resource elements (REs). For example, one RE may be a radio resource region of one subcarrier and one symbol.

[0175] A Bandwidth Part (BWP) (which may also be referred to as a fractional bandwidth) may represent a subset of contiguous common resource blocks (RBs) for a given numerology on a given carrier, where the common RBs may be identified by their index relative to a common reference point of the carrier. PRBs may be defined in a given BWP and numbered within that BWP.

[0176] The BWP may include a BWP for UL (UL BWP) and a BWP for DL ​​(DL BWP). One or more BWPs may be configured for a UE within one carrier.

[0177] At least one of the configured BWPs may be active, and the UE may not expect to transmit or receive a given signal / channel outside the active BWP. Note that the terms "cell," "carrier," etc. in this disclosure may be read as "BWP."

[0178] The above-described structures of the radio frame, subframe, slot, minislot, and symbol are merely examples. For example, the number of subframes included in a radio frame, the number of slots per subframe or radio frame, the number of minislots included in a slot, the number of symbols and RBs included in a slot or minislot, the number of subcarriers included in an RB, the number of symbols in a TTI, the symbol length, the cyclic prefix (CP) length, and other configurations may be changed in various ways.

[0179] The terms "connected," "coupled," or any variation thereof, refer to any direct or indirect connection or coupling between two or more elements, and may include the presence of one or more intermediate elements between two elements that are "connected" or "coupled" to each other. The coupling or connection between elements may be physical, logical, or a combination thereof. For example, "connected" may be read as "access." As used in this disclosure, two elements may be considered to be "connected" or "coupled" to each other using one or more wires, cables, and / or printed electrical connections, as well as electromagnetic energy having wavelengths in the radio frequency range, microwave range, and optical (both visible and invisible) range, as some non-limiting and non-exhaustive examples.

[0180] The reference signal may also be abbreviated as Reference Signal (RS) and may be called a pilot depending on the applicable standard.

[0181] As used in this disclosure, the phrase "based on" does not mean "based only on," unless expressly stated otherwise. In other words, the phrase "based on" means both "based only on" and "based at least on."

[0182] The "means" in the configuration of each of the above devices may be replaced with "part," "circuit," "device," etc.

[0183] As used in this disclosure, any reference to an element using a designation such as "first," "second," etc. does not generally limit the quantity or order of those elements. These designations may be used in this disclosure as a convenient method of distinguishing between two or more elements. Thus, a reference to a first and a second element does not imply that only two elements may be employed therein or that the first element must precede the second element in some way.

[0184] When the terms "include," "including," and variations thereof are used in this disclosure, these terms are intended to be inclusive, similar to the term "comprising." Furthermore, when the term "or" is used in this disclosure, it is not intended to be an exclusive or.

[0185] In this disclosure, where articles are added by translation, such as a, an, and the in English, the disclosure may include that the nouns following these articles are in the plural form.

[0186] As used in this disclosure, the terms "determining" and "determining" may encompass a wide variety of actions. "Determining" and "determining" may include, for example, judging, calculating, computing, processing, deriving, investigating, looking up, searching, inquiring (e.g., searching in a table, database, or other data structure), ascertaining, and the like. "Determining" and "determining" may also include receiving (e.g., receiving information), transmitting (e.g., sending information), input, output, accessing (e.g., accessing data in memory), and the like. Furthermore, "judgment" and "decision" can include regarding resolving, selecting, choosing, establishing, comparing, etc. as having been "judged" or "decided." In other words, "judgment" and "decision" can include regarding some action as having been "judged" or "decided." Furthermore, "judgment (decision)" can be interpreted as "assuming," "expecting," "considering," etc.

[0187] In the present disclosure, the term "A and B are different" may mean "A and B are different from each other." The term may also mean "A and B are each different from C." Terms such as "separate" and "coupled" may also be interpreted in the same way as "different."

[0188] 12 shows an example of the configuration of a vehicle 2001. As shown in Fig. 12, the vehicle 2001 includes a drive unit 2002, a steering unit 2003, an accelerator pedal 2004, a brake pedal 2005, a shift lever 2006, left and right front wheels 2007, left and right rear wheels 2008, an axle 2009, an electronic control unit 2010, various sensors 2021 to 2029, an information service unit 2012, and a communication module 2013.

[0189] The drive unit 2002 is composed of, for example, an engine, a motor, or a hybrid of an engine and a motor. The steering unit 2003 includes at least a steering wheel (also called a handle) and is configured to steer at least one of the front wheels and the rear wheels based on the operation of the steering wheel operated by the user. The electronic control unit 2010 is composed of a microprocessor 2031, memory (ROM, RAM) 2032, and a communication port (IO port) 2033. Signals from various sensors 2021 to 2027 provided in the vehicle are input to the electronic control unit 2010. The electronic control unit 2010 may also be called an ECU (Electronic Control Unit).

[0190] The signals from the various sensors 2021 to 2028 include a current signal from a current sensor 2021 that senses the current of the motor, a rotation speed signal of the front and rear wheels obtained by a rotation speed sensor 2022, an air pressure signal of the front and rear wheels obtained by an air pressure sensor 2023, a vehicle speed signal obtained by a vehicle speed sensor 2024, an acceleration signal obtained by an acceleration sensor 2025, an accelerator pedal depression amount signal obtained by an accelerator pedal sensor 2029, a brake pedal depression amount signal obtained by a brake pedal sensor 2026, a shift lever operation signal obtained by a shift lever sensor 2027, and a detection signal for detecting obstacles, vehicles, pedestrians, etc. obtained by an object detection sensor 2028.

[0191] The information service unit 2012 is composed of various devices, such as a car navigation system, an audio system, speakers, a television, and a radio, for providing (outputting) various types of information, such as driving information, traffic information, and entertainment information, and one or more ECUs for controlling these devices. The information service unit 2012 uses information acquired from external devices via the communication module 2013, etc., to provide various types of multimedia information and multimedia services to the occupants of the vehicle 1.

[0192] The information service unit 2012 may include input devices (e.g., keyboards, mice, microphones, switches, buttons, sensors, touch panels, etc.) that accept input from the outside, and may also include output devices (e.g., displays, speakers, LED lamps, touch panels, etc.) that output to the outside.

[0193] The driving assistance system unit 2030 is composed of various devices that provide functions for preventing accidents and reducing the driver's driving burden, such as millimeter-wave radar, LiDAR (Light Detection and Ranging), cameras, positioning locators (e.g., GNSS, etc.), map information (e.g., high-definition (HD) maps, autonomous vehicle (AV) maps, etc.), gyro systems (e.g., IMU (Inertial Measurement Unit), INS (Inertial Navigation System), etc.), AI (Artificial Intelligence) chips, and AI processors, as well as one or more ECUs that control these devices. The driving assistance system unit 2030 also transmits and receives various information via the communication module 2013 to realize driving assistance functions or autonomous driving functions.

[0194] The communication module 2013 can communicate with the microprocessor 2031 and components of the vehicle 1 via the communication port. For example, the communication module 2013 transmits and receives data via the communication port 2033 to and from a driving unit 2002, a steering unit 2003, an accelerator pedal 2004, a brake pedal 2005, a shift lever 2006, left and right front wheels 2007, left and right rear wheels 2008, an axle 2009, a microprocessor 2031 and memory (ROM, RAM) 2032 in the electronic control unit 2010, and sensors 2021 to 2028, which are provided in the vehicle 2001.

[0195] The communication module 2013 is a communication device that can be controlled by the microprocessor 2031 of the electronic control unit 2010 and can communicate with an external device. For example, it transmits and receives various information to and from the external device via wireless communication. The communication module 2013 may be located either inside or outside the electronic control unit 2010. The external device may be, for example, a base station, a mobile station, or the like.

[0196] The communication module 2013 may transmit at least one of signals from the above-mentioned various sensors 2021 to 2028 input to the electronic control unit 2010, information obtained based on the signals, and information based on input from the outside (user) obtained via the information service unit 2012 to an external device via wireless communication. The electronic control unit 2010, the various sensors 2021 to 2028, the information service unit 2012, etc. may be referred to as input units that accept input. For example, the PUSCH transmitted by the communication module 2013 may include information based on the above-mentioned input.

[0197] The communication module 2013 receives various information (traffic information, traffic signal information, vehicle-to-vehicle information, etc.) transmitted from external devices and displays it on an information service unit 2012 provided in the vehicle. The information service unit 2012 may also be called an output unit that outputs information (for example, outputs information to a device such as a display or speaker based on the PDSCH (or data / information decoded from the PDSCH) received by the communication module 2013). The communication module 2013 also stores the various information received from external devices in a memory 2032 that can be used by the microprocessor 2031. Based on the information stored in the memory 2032, the microprocessor 2031 may control the drive unit 2002, steering unit 2003, accelerator pedal 2004, brake pedal 2005, shift lever 2006, left and right front wheels 2007, left and right rear wheels 2008, axles 2009, sensors 2021 to 2028, and the like provided in the vehicle 2001.

[0198] (Additional Note) The above disclosure may be expressed as follows: A first feature is a terminal including: a receiver that receives a reference signal associated with an altitude; and a controller that performs measurement using the reference signal associated with the altitude at which the terminal is located.

[0199] A second feature is that, in the first feature, the device further includes a transmitting unit that transmits a measurement report to a network, the measurement report including information indicating an altitude at which the terminal is located, and the receiving unit receives the reference signal associated with the altitude at which the terminal is located.

[0200] A third feature is a wireless communication system including a first radio base station and a second radio base station, wherein the first radio base station includes a control unit that controls cell transition of a terminal in accordance with mobility control by a lower layer, and a transmission unit that transmits altitude information indicating an altitude at which the terminal is located to the second radio base station, and the second radio base station includes a receiving unit that receives the altitude information, and a control unit that sets a resource for a reference signal associated with the altitude based on the altitude information.

[0201] In a fourth feature based on the third feature, the control unit of the second radio base station sets a plurality of resources for reference signals each associated with a different altitude.

[0202] 10 Wireless communication system 20 NG-RAN 100, 100A to 100D gNB 200 UE 210 Radio signal transceiver 220 Amplifier 230 Modulation / demodulation unit 240 Control signal / reference signal processing unit 250 Encoding / decoding unit 260 Data transceiver 270 Control unit 1001 Processor 1002 Memory 1003 Storage 1004 Communication device 1005 Input device 1006 Output device 1007 Bus 2001 Vehicle 2002 Drive unit 2003 Steering unit 2004 Accelerator pedal 2005 Brake pedal 2006 Shift lever 2007 Left and right front wheels 2008 Left and right rear wheels 2009 Axle 2010 Electronic control unit 2012 Information service unit 2013 Communication module 2021 Current sensor 2022 RPM sensor 2023 Air pressure sensor 2024 Vehicle speed sensor 2025 Acceleration sensor 2026 Brake pedal sensor 2027 Shift lever sensor 2028 Object detection sensor 2029 Accelerator pedal sensor 2030 Driving assistance system section 2031 Microprocessor 2032 Memory (ROM, RAM) 2033 Communication port

Claims

1. A terminal comprising: a receiving unit that receives a reference signal associated with an altitude; and a control unit that performs measurements using the reference signal associated with the altitude at which the terminal is located.

2. A terminal as described in claim 1, further comprising a transmitting unit that transmits a measurement report including information indicating an altitude at which the terminal is located to a network, and wherein the receiving unit receives the reference signal associated with the altitude at which the terminal is located.

3. A wireless communication system including a first radio base station and a second radio base station, wherein the first radio base station comprises: a control unit that controls cell transition of a terminal in accordance with mobility control by a lower layer; and a transmission unit that transmits altitude information indicating the altitude at which the terminal is located to the second radio base station, and the second radio base station comprises: a reception unit that receives the altitude information; and a control unit that sets resources for a reference signal associated with the altitude based on the altitude information.

4. The wireless communication system according to claim 3, wherein the control unit of the second wireless base station sets a plurality of resources for reference signals each corresponding to a different altitude.

5. A wireless communication method in a terminal, comprising: a step of receiving a reference signal associated with an altitude; and a step of performing measurements using the reference signal associated with the altitude at which the terminal is located.

6. A wireless communication method in a wireless communication system including a first radio base station and a second radio base station, comprising: a step in which the first radio base station controls cell transition of a terminal in accordance with mobility control by a lower layer; a step in which the first radio base station transmits altitude information indicating the altitude at which the terminal is located to the second radio base station; a step in which the second radio base station receives the altitude information; and a step in which the second radio base station sets resources for a reference signal associated with the altitude based on the altitude information.

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