Communication method, aviation user equipment, and network node

Abstract

A communication method executed by aviation user equipment in a mobile communication system comprises: receiving, from a network node, broadcast information used for transmission restriction on specific uplink transmission performed in a radio resource control (RRC) idle state or an RRC inactive state by the aviation user equipment; determining, on the basis of the broadcast information, whether a specific condition for performing the transmission restriction on the specific uplink transmission is satisfied; and performing the transmission restriction on the specific uplink transmission in the RRC idle state or the RRC inactive state in response to it being determined that the specific condition is satisfied.

Description

Communication method, aerial user equipment, and network node

[0001] The present disclosure relates to a communication method, an aerial user equipment, and a network node used in a mobile communication system.

[0002] In 3GPP (3rd Generation Partnership Project) (registered trademark; the same shall apply hereinafter), the technical specifications of NR (New Radio), which is a 5th generation (5G) radio access technology, are defined. The 3GPP mobile communication system supports an aerial UE (Aerial User Equipment), which is a user equipment (UE) capable of aerial communication. The aerial UE 100 may be an Unmanned Aircraft Vehicle (UAV) such as a drone.

[0003] 3GPP technical specification "3GPP TS 38.300 V18.2.0 (2024-06)"

[0004] The present disclosure provides a technology that enables reduction of uplink interference caused by an aerial user equipment.

[0005] The communication method according to the first aspect of the present disclosure is a communication method executed by an aerial user equipment in a mobile communication system, including receiving, from a network node, broadcast information used for transmission restriction on specific uplink transmission performed in an RRC (Radio Resource Control) idle state or an RRC inactive state by the aerial user equipment; determining whether a specific condition for performing the transmission restriction on the specific uplink transmission is satisfied based on the broadcast information; and performing the transmission restriction on the specific uplink transmission in the RRC idle state or the RRC inactive state in response to determining that the specific condition is satisfied.

[0006] An aerial user device according to a second aspect of this disclosure is an aerial user device used in a mobile communication system, comprising: a receiving unit that receives broadcast information from a network node used for transmission restriction on a specific uplink transmission performed by the aerial user device in a radio resource control (RRC) idle state or RRC inactive state; and a control unit that determines, based on the broadcast information, whether or not specific conditions for performing the transmission restriction on the specific uplink transmission have been met. The control unit performs the transmission restriction on the specific uplink transmission in the RRC idle state or RRC inactive state in response to the determination that the specific conditions have been met.

[0007] A network node according to a third aspect of this disclosure is a network node used in a mobile communication system and includes a transmitting unit that transmits broadcast information used for transmission restrictions on specific uplink transmissions performed by an aviation user device in a radio resource control (RRC) idle state or RRC inactive state.

[0008] This figure shows an example configuration of a mobile communication system according to the embodiment. This figure shows an example configuration of a UE (User Equipment) according to the embodiment. This figure shows an example configuration of a gNB (Network Node) according to the embodiment. This figure shows the configuration of the protocol stack of the wireless interface of the user plane that handles data. This figure shows the configuration of the protocol stack of the wireless interface of the control plane that handles signaling (control signals). This figure shows an RA-SDT procedure using two-step random access. This figure shows an RA-SDT procedure using four-step random access. This figure shows a CG-SDT procedure. This figure shows an example of an operation scenario of the mobile communication system according to the embodiment. This figure shows an overview of the operation of the aviation UE according to the embodiment. This figure shows a first operation example of the mobile communication system according to the embodiment. This figure shows a second operation example of the mobile communication system according to the embodiment. This figure shows a third operation example of the mobile communication system according to the embodiment.

[0009] A mobile communication system according to an embodiment will be described with reference to the drawings. In the drawings, identical or similar parts are denoted by the same or similar reference numerals.

[0010] (1) The mobile communication system configuration diagram 1 is a diagram showing an example of the configuration of the mobile communication system 1 according to this embodiment. The mobile communication system 1 conforms to the 5th generation system (5GS: 5th Generation System) of the 3GPP standard. In the following description, 5GS will be used as an example, but the mobile communication system may also have an LTE (Long Term Evolution) system applied to it at least partially. The mobile communication system may also have a 6th generation (6G) system applied to it at least partially.

[0011] The mobile communication system 1 comprises a user equipment (UE) 100, a 5G radio access network (NG-RAN: Next Generation Radio Access Network) 10, and a 5G core network (5GC: 5G Core Network) 20. Hereinafter, NG-RAN 10 may be simply referred to as RAN 10, and 5GC 20 may be simply referred to as the core network (CN) 20. RAN 10 and CN 20 constitute the network 5 of the mobile communication system 1.

[0012] UE100 is a mobile wireless communication device. UE100 can be any device used by a user. For example, UE100 can be a mobile phone terminal (including a smartphone) and / or a tablet terminal, a notebook PC, a communication module (including a communication card or chipset), a sensor or a device attached to a sensor, a vehicle or a device attached to a vehicle (Vehicle UE), or an aircraft or a device attached to an aircraft (Aerial UE). The link from UE100 to network 5 in the transmission direction is called the uplink (UL), and the link from network 5 to UE100 in the transmission direction is called the downlink (DL).

[0013] NG-RAN10 includes a base station (referred to as "gNB" in the 5G system) 200, which is a type of network node. The gNBs 200 are interconnected via the Xn interface, which is an inter-base station interface. The gNBs 200 manage one or more cells. The gNBs 200 perform wireless communication with UEs 100 that have established a connection with their own cell. The gNBs 200 have radio resource management (RRM) functions, user data (hereinafter simply referred to as "data") routing functions, measurement and control functions for mobility control and scheduling, etc. "Cell" is used as a term to indicate the smallest unit of a wireless communication area. "Cell" is also used as a term to indicate a function or resource that performs wireless communication with a UE 100. One cell belongs to one carrier frequency (hereinafter simply referred to as "frequency").

[0014] Furthermore, gNBs can also connect to the EPC (Evolved Packet Core), which is the core network of LTE. LTE base stations can also connect to 5GC. LTE base stations and gNBs can also be connected via an inter-base station interface.

[0015] 5GC20 includes AMF (Access and Mobility Management Function) and UPF (User Plane Function) 300. The AMF performs various mobility controls for UE100. The AMF manages the mobility of UE100 by communicating with UE100 using NAS (Non-Access Stratum) signaling. The UPF controls data transfer. The AMF and UPF are connected to gNB200 via the NG interface, which is the base station-core network interface.

[0016] Figure 2 shows an example configuration of UE100 (user device) according to this embodiment. UE100 includes a receiving unit 110, a transmitting unit 120, and a control unit 130. The receiving unit 110 and the transmitting unit 120 constitute a wireless communication unit 140 that performs wireless communication with gNB200.

[0017] The receiving unit 110 performs various types of reception under the control of the control unit 130. The receiving unit 110 includes an antenna and a receiver. The receiver converts the radio signal received by the antenna into a baseband signal (received signal) and outputs it to the control unit 130.

[0018] The transmitting unit 120 performs various types of transmissions under the control of the control unit 130. The transmitting unit 120 includes an antenna and a transmitter. The transmitter converts the baseband signal (transmission signal) output by the control unit 130 into a wireless signal and transmits it from the antenna.

[0019] The control unit 130 performs various control and processing operations in the UE 100. Such processing includes processing in each layer described later. The operation of the UE 100 described above and later may also be controlled by the control unit 230. The control unit 130 includes at least one processor and at least one memory. The memory stores programs executed by the processor and information used for processing by the processor. The processor may include a baseband processor and a CPU (Central Processing Unit). The baseband processor performs modulation, demodulation, encoding, and decoding of baseband signals. The CPU executes programs stored in memory and performs various processing operations.

[0020] Figure 3 shows an example configuration of a gNB200 (network node) according to this embodiment. The gNB200 includes a transmitting unit 210, a receiving unit 220, a control unit 230, and a network communication unit 240. The transmitting unit 210 and the receiving unit 220 constitute a wireless communication unit 250 that performs wireless communication with the UE100. The network communication unit 240 includes a transmitting unit 241 that performs transmission and a receiving unit 242 that performs reception.

[0021] The transmitting unit 210 performs various types of transmissions under the control of the control unit 230. The transmitting unit 210 includes an antenna and a transmitter. The transmitter converts the baseband signal (transmission signal) output by the control unit 230 into a wireless signal and transmits it from the antenna.

[0022] The receiving unit 220 performs various types of reception under the control of the control unit 230. The receiving unit 220 includes an antenna and a receiver. The receiver converts the radio signal received by the antenna into a baseband signal (received signal) and outputs it to the control unit 230.

[0023] The control unit 230 performs various control and processing operations in the gNB 200. Such processing includes processing in each layer described later. The operation of the gNB 200 described above and later may also be controlled by the control unit 230. The control unit 230 includes at least one processor and at least one memory. The memory stores programs executed by the processor and information used in processing by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation, demodulation, encoding, decoding, etc. of the baseband signal. The CPU executes programs stored in memory and performs various processing operations.

[0024] The network communication unit 240 is connected to an adjacent base station via the Xn interface, which is an inter-base station interface. The network communication unit 240 is connected to the AMF / UPF 300 via the NG interface, which is an inter-base station-core network interface. The gNB 200 may consist of a CU (Central Unit) and a DU (Distributed Unit) (i.e., functionally separated), and the two units may be connected by the F1 interface, which is a front-haul interface.

[0025] Figure 4 shows the configuration of the protocol stack for the user plane's wireless interface that handles data.

[0026] The user plane radio interface protocol comprises a physical (PHY) layer, a MAC (Medium Access Control) layer, an RLC (Radio Link Control) layer, a PDCP (Packet Data Convergence Protocol) layer, and an SDAP (Service Data Adaptation Protocol) layer.

[0027] The PHY layer performs encoding / decoding, modulation / demodulation, antenna mapping / demapping, and resource mapping / demapping. Data and control information are transmitted between the PHY layer of UE100 and the PHY layer of gNB200 via a physical channel. The PHY layer of UE100 receives downlink control information (DCI) transmitted from gNB200 on the physical downlink control channel (PDCCH). Specifically, UE100 performs blind decoding of the PDCCH using a Radio Network Temporary Identifier (RNTI) and acquires the successfully decoded DCI as the DCI addressed to its own UE. The DCI transmitted from gNB200 has a CRC (Cyclic Redundancy Code) parity bit added, which is scrambled by the RNTI.

[0028] The MAC layer performs data priority control, retransmission processing using Hybrid ARQ (HARQ: Hybrid Automatic Repeat reQuest), and random access procedures. Data and control information are transmitted between the MAC layer of UE100 and the MAC layer of gNB200 via the transport channel. The MAC layer of gNB200 includes a scheduler. The scheduler determines the transport format for the up and down links (transport block size, modulation and coding scheme (MCS)) and the resource blocks to be allocated to UE100.

[0029] The RLC layer transmits data to the receiving RLC layer using the functions of the MAC layer and PHY layer. Data and control information are transmitted between the RLC layer of UE100 and the RLC layer of gNB200 via a logical channel.

[0030] The PDCP layer performs header compression / decompression, encryption / decryption, etc.

[0031] The SDAP layer maps IP flows, which are the units under which the core network performs QoS (Quality of Service) control, to wireless bearers, which are the units under which the AS (Access Stratum) performs QoS control. Note that if the RAN is connected to the EPC, the SDAP is not required.

[0032] Figure 5 shows the configuration of the protocol stack of the wireless interface of the control plane that handles signaling (control signals).

[0033] The protocol stack of the control plane's wireless interface includes an RRC (Radio Resource Control) layer and a NAS (Non-Access Stratum) layer, instead of the SDAP layer shown in Figure 4.

[0034] RRC signaling for various settings is transmitted between the RRC layer of the UE100 and the RRC layer of the gNB200. The RRC layer controls the logical channel, transport channel, and physical channel in response to the establishment, re-establishment, and release of the radio bearer. If there is a connection (RRC connection) between the RRC of the UE100 and the RRC of the gNB200, the UE100 is in the RRC connected state. If there is no connection (RRC connection) between the RRC of the UE100 and the RRC of the gNB200, the UE100 is in the RRC idle state. If the connection between the RRC of the UE100 and the RRC of the gNB200 is suspended, the UE100 is in the RRC inactive state.

[0035] The NAS layer (also simply referred to as "NAS"), located above the RRC layer, handles session management and mobility management, among other things. NAS signaling is transmitted between the NAS layer of the UE100 and the NAS layer of the AMF300. The UE100 also has an application layer in addition to the wireless interface protocol. Furthermore, the layer below the NAS layer is called the AS layer (also simply referred to as "AS").

[0036] (2) Overview of Small Data Transmission (SDT) The mobile communication system 1 according to this embodiment supports small data transmission (SDT).

[0037] For example, IoT (Internet of Things) devices such as sensor equipment communicate only occasionally, sending small amounts of data and then remaining in a state where no further data is transmitted. Because the data from IoT devices (user data) is small, establishing a connection just to transmit such a small amount of data is undesirable from the standpoint of overhead and power consumption.

[0038] In the mobile communication system 1, a vast number of IoT devices can communicate, so SDT is required to enable the smooth operation of network 5. Using SDT, UE100 can transmit a small amount of data while RRC is inactive. In other words, UE100 transmits a small amount of data without an RRC connection.

[0039] SDT is enabled on a per-wireless bearer basis and initiated by UE100. However, UE100 can only apply SDT in each wireless bearer where SDT is enabled if the amount of uplink data waiting to be transmitted is less than a set amount; otherwise, the normal data transmission method (i.e., the method of transitioning to the RRC connected state and transmitting uplink data) may be used.

[0040] SDTs include Random Access (RA-) SDTs and Configured Grant (CG-) SDTs.

[0041] In RA-SDT, UE100 performs race-based RA procedures without dedicated wireless resources for the UE. UE100 can determine the available wireless resources for RA procedures based on system information messages (i.e., SIBs). However, RA wireless resources are separated between SDT and non-SDT systems.

[0042] The RA-SDT procedure uses a two-step or four-step random access procedure. In either case, UE100 maintains an RRC inactive state during the procedure.

[0043] FIG. 6 is a diagram showing an RA-SDT procedure using two-step random access.

[0044] In the RA-SDT procedure using two-step random access, when uplink data is generated (step S12) in the UE 100 in the RRC inactive state (step S11), the uplink data is transmitted to the gNB 200 by MsgA in the two-step random access (step S13). MsgA includes an RA preamble, an RRC Resume Request message, and uplink data (payload data). The gNB 200 that has received MsgA including the uplink data transmits MsgB to the UE 100 (step S14). MsgB includes an RA response and an RRC Release message for maintaining the UE 100 in the RRC inactive state.

[0045] FIG. 7 is a diagram showing an RA-SDT procedure using four-step random access.

[0046] In the RA-SDT procedure using four-step random access, when uplink data is generated (step S22) in the UE 100 in the RRC inactive state (step S21), the UE 100 transmits an RA preamble to the gNB 200 on the physical random access channel (PRACH) as Msg1 (step S23). The gNB 200 that has received the RA preamble transmits an RA response to the UE 100 as Msg2 (step S24). The UE 100 that has received the RA response transmits an RRC Resume Request message and uplink data (payload data) to the gNB 200 as Msg3 (step S25). The gNB 200 that has received Msg3 including the uplink data transmits an RRC Release message for maintaining the UE 100 in the RRC inactive state to the UE 100 (step S26).

[0047] FIG. 8 is a diagram showing a CG-SDT procedure.

[0048] In the CG-SDT procedure, the gNB 200 transmits (step S31) an RRC Release message for maintaining the UE 100 in the RRC inactive state to the UE 100 in the RRC connected state. The RRC Release message includes a CG setting containing information indicating uplink radio resources. The uplink radio resources are periodically allocated based on the traffic requirements of the UE 100. In CG-SDT, since the uplink radio resources are allocated dedicatedly to each UE, message collisions between UEs do not occur. The UE 100 that receives the RRC Release message transitions (step S32) to the RRC inactive state. When uplink data is generated (step S33) in the UE 100 in the RRC inactive state, the UE 100 transmits (step S34) an RRC Resume Request message and uplink data (payload data) to the gNB 200 using the allocated uplink radio resources. The gNB 200 that receives Msg3 including the uplink data transmits (step S35) an RRC Release message for maintaining the UE 100 in the RRC inactive state to the UE 100.

[0049] If the CG-SDT resources are set on the selected uplink carrier in the UE 100, the UE 100 selects CG-SDT as the type of SDT. If the CG-SDT resources are unavailable or invalid, the UE 100 selects RA-SDT if RA-SDT is set. If no SDT is set, the UE 100 performs normal data transmission (non-SDT data transmission). In the case of normal data transmission, the UE 100 transitions from the RRC inactive state to the RRC connected state and transmits the uplink data to the gNB 200.

[0050] (3) Operations according to the embodiment The operations according to this embodiment will be described.

[0051] (3.1) Operation Overview Diagram 9 is a diagram showing an example of an operation scenario of the mobile communication system 1 according to this embodiment. The mobile communication system 1 according to this embodiment supports Aerial UE. The Aerial UE is a UE 100 capable of Aerial Communication. The Aerial UE 100 may be an Unmanned Aircraft Vehicle (UAV) such as a drone.

[0052] In the illustrated example, gNB200a manages cell a, and gNB200b manages cell b. Cell a is a serving cell of UE100, and cell b is a non-serving cell of UE100. gNB200a forms cell a facing upwards to provide upper-air coverage. gNB200b forms cell b facing downwards to provide ground coverage. However, cells a and b may be managed and formed by a single gNB200.

[0053] In the mobile communication system 1, cells for upper-air coverage and cells for ground coverage may be mixed. In cells for upper-air coverage, one or more beams for upper-air coverage are formed. In beams for upper-air coverage, the main lobe may be pointed upwards while the side lobes are pointed towards the ground. In cells for ground coverage, one or more beams for ground coverage are formed. In beams for ground coverage, the main lobe may be pointed towards the ground while the side lobes are pointed upwards. Each beam may be identified by a synchronization signal block (SSB: SS / PBCH block).

[0054] The Aerial UE100 can communicate wirelessly with the gNB200 in the airspace while flying. However, it is assumed that the Aerial UE100 will not perform continuous high-capacity data transmission. Under these assumptions, the Aerial UE100 does not necessarily need to maintain the RRC connected state; it may transition to the RRC idle state after data transmission is complete, or to the RRC inactive state for small data transmission.

[0055] In this embodiment, it is primarily assumed that the aerial UE 100, in an RRC inactive state, performs data transmission using SDT. In uplink data transmission using SDT, unlike uplink data transmission in an RRC connected state, it is difficult for the gNB 200 to appropriately control the transmission power of the UE 100. Under such circumstances, when the aerial UE 100 performs data transmission using SDT, there is a problem that it will interfere with the non-serving cells of the aerial UE 100. In particular, because the aerial UE 100 flies in the air, the radio signals transmitted by the aerial UE 100 reach farther in line of sight than a normal UE 100 on the ground, and will interfere with distant non-serving cells (for example, cell b shown in Figure 9).

[0056] Meanwhile, in Release 18 of the 3GPP standard, power control information for the Aerial UE100 (nr-NS-PmaxListAerial-r18) has been introduced. This power control information includes, for each frequency band, information indicating the maximum transmit power for the Aerial UE100 (P-Max) and information indicating the spectrum emission requirements that the Aerial UE100 must meet (AdditionalSpectrumEmission-r18). This power control information is included in the SIB transmitted by the gNB200. The Aerial UE100 performs uplink transmit power control based on the power control information for the Aerial UE100 (nr-NS-PmaxListAerial-r18) during RRC idle, RRC inactive, and RRC re-establishment states.

[0057] However, this power control information (nr-NS-PmaxListAerial-r18) was introduced to meet the spurious emission (out-of-band leakage power) limiting requirements, and not to mitigate interference on the uplink to non-serving cells. Therefore, there is a concern that this power control information (nr-NS-PmaxListAerial-r18) may not provide sufficient settings to mitigate interference on the uplink. In particular, it is considered insufficient to mitigate interference on the uplink when the aviation UE100 transmits data using SDT.

[0058] Therefore, this embodiment provides a technology that makes it possible to reduce interference on the uplink by the aircraft UE100.

[0059] The following embodiments will primarily describe operations to mitigate interference on the uplink when an aircraft UE 100 in an RRC inactive state performs data transmission via SDT.

[0060] However, even the transmission of RA preambles in normal RA procedures performed by an aircraft UE 100 in an RRC inactive or RRC idle state can cause interference on the uplink. Therefore, the operation according to the following embodiment may be applied to an aircraft UE 100 in an RRC idle state, not limited to the RRC inactive state.

[0061] Figure 10 is a diagram illustrating the overview of the operation of the aerial UE 100 according to this embodiment.

[0062] In step S1, the aviation UE 100 receives broadcast information from the gNB 200 to be used for transmission restrictions on specific uplink transmissions performed in the RRC idle state or RRC inactive state. Broadcast information is information transmitted on a broadcast channel (e.g., SIB) that can be received by the UE 100 in the RRC idle state or RRC inactive state.

[0063] In step S2, the aviation UE 100 determines, based on the broadcast information received in step S1, whether or not specific conditions for restricting transmission to a specific uplink transmission have been met. The specific conditions may be defined in advance in the technical specifications. Alternatively, the specific conditions may be set from the gNB 200 to the aviation UE 100.

[0064] In step S3, the aviation UE 100, in response to the determination that specific conditions were met in step S2, imposes a transmission restriction on a specific uplink transmission in the RRC idle state or RRC inactive state.

[0065] The aerial UE 100 performing this operation includes a receiving unit 110 that receives broadcast information from the gNB 200 used for transmission restriction on specific uplink transmissions performed by the aerial UE 100 in an RRC idle state or RRC inactive state, and a control unit 130 that determines whether or not specific conditions for performing transmission restriction on specific uplink transmissions have been met based on the broadcast information (see Figure 2). The control unit 130 performs transmission restriction on specific uplink transmissions in an RRC idle state or RRC inactive state in response to the determination that the specific conditions have been met. On the other hand, the gNB 200 includes a transmitting unit 210 that transmits broadcast information used for transmission restriction on specific uplink transmissions performed by the aerial UE 100 in an RRC idle state or RRC inactive state (see Figure 3).

[0066] The specific uplink transmission may be a small data transmission (SDT) in which the aviation UE 100 transmits uplink data to the network 5 (gNB 200) while the RRC is inactive. The SDT may be a 4-step RA-SDT, a 2-step RA-SDT, or a CG-SDT. In this case, the aviation UE 100 restricts the transmission of the SDT in accordance with the determination that specific conditions have been met in step S2. This makes it possible to reduce interference on the uplink caused by the aviation UE 100's SDT.

[0067] Alternatively, the specific uplink transmission may be a physical random access channel (PRACH) transmission in which the aviation UE 100, in an RRC idle or RRC inactive state, sends an RA preamble to the network 5 (gNB 200). In this case, the aviation UE 100 restricts the transmission of PRACH transmissions depending on whether it is determined in step S2 that a specific condition has been met. This makes it possible to reduce the interference on the uplink caused by the aviation UE 100's PRACH transmissions.

[0068] In the following embodiments, we primarily assume that the specific uplink transmission is data transmission via SDT.

[0069] The broadcast information received by the aviation UE 100 in step S1 may include power control information. The transmission limit in step S3 may be controlled by controlling the uplink transmission power in a specific uplink transmission based on the power control information. The power control information may be different from the power control information (nr-NS-PmaxListAerial-r18) introduced in Release 18 of the 3GPP standard, and may be, for example, information that has a greater effect on reducing uplink transmission power than nr-NS-PmaxListAerial-r18. The aviation UE 100 may control the uplink transmission power in the SDT in response to the determination that a specific condition has been met in step S2. This makes it possible to reduce the interference on the uplink by the aviation UE 100's SDT.

[0070] The power control information may be applied to PUSCH (Physical Uplink Shared Channel) transmissions, for example, data transmissions via SDT. Alternatively, the power control information may be applied to PRACH (Physical Random Access Channel) transmissions. The power control information may also be applied to both PRACH and PUSCH transmissions.

[0071] The power control information may include power control parameters for limiting the uplink transmit power in a specific uplink transmission. The power control parameters are at least one of the following: information indicating the maximum transmit power for the aviation UE100 (P-Max), information indicating the spectrum emission requirements that the aviation UE100 must satisfy, and a variable (α) applied to the uplink transmit power calculation formula. The variable (α) may be a coefficient multiplied by the path loss (PL) in the uplink transmit power calculation formula. Generally, the UE100 increases the uplink transmit power as the path loss between the UE100 and the gNB200 increases, but the uplink transmit power can be limited by the variable (α). If the uplink transmit power calculated by the formula is less than the maximum transmit power, the UE100 applies the calculated uplink transmit power to the uplink transmission. On the other hand, if the uplink transmit power calculated by the formula is greater than the maximum transmit power, the UE100 applies the maximum transmit power to the uplink transmission.

[0072] UE100 may compare the power control information with the power control information introduced in Release 18 of the 3GPP standard (nr-NS-PmaxListAerial-r18) and apply whichever results in a lower uplink transmit power.

[0073] The power control parameter may be an offset value applied to the power control parameter of the power control information (nr-NS-PmaxListAerial-r18) introduced in Release 18 of the 3GPP standard. That is, the power control parameter may be intended to impose stricter limits on the uplink transmit power of the aviation UE100 than the power control information (nr-NS-PmaxListAerial-r18) introduced in Release 18 of the 3GPP standard.

[0074] Alternatively, the transmission restriction in step S3 may be to refrain from performing a specific uplink transmission when specific conditions are met. In this case, the aviation UE 100 may refrain from performing the SDT in response to the determination in step S2 that the specific conditions have been met. This makes it possible to reduce the interference on the uplink caused by the aviation UE 100's SDT. When the aviation UE 100 refrains from performing the SDT, it may perform a normal uplink data transmission (non-SDT data transmission). In a normal data transmission, the aviation UE 100 may transition from the RRC inactive state to the RRC connected state and transmit uplink data to the gNB 200.

[0075] The broadcast information received by the aviation UE100 in step S1 may include conditional information indicating specific conditions. This allows the network 5 (gNB200) to specify conditions for restricting transmission to a specific uplink transmission.

[0076] The specific conditions may include condition 1, which states that the aerial UE100 is in flight. Although the aerial UE100 is capable of aerial communication, it can also perform ground communication like a normal UE100. When the aerial UE100 is performing ground communication, there is little need to restrict transmission for specific uplink transmissions. Therefore, the aerial UE100 may be restricted from performing transmission for specific uplink transmissions only when it is in flight. It should be noted that the aerial UE100 generally has a GNSS (Global Navigation Satellite System) receiver and is capable of determining its own latitude, longitude, and altitude. The aerial UE100 may determine whether or not it is in flight based on positioning information. The aerial UE100 may determine whether or not it is in flight based on information from its application layer, etc.

[0077] Conditional information may include information specifying a cell or SSB, for example, a cell identifier or SSB identifier. Specific conditions may include condition 2 that the cell selected by the aerial UE 100 (i.e., the serving cell where the aerial UE 100 is camping) or SSB matches the specified cell or SSB. The specified cell or SSB may be a cell or SSB that provides airspace coverage. The specified cell or SSB may be a cell or SSB that should mitigate interference to non-serving cells.

[0078] Conditional information may include an altitude threshold. Specific conditions may include condition 3, which states that the altitude of aircraft UE100 exceeds the altitude threshold.

[0079] The condition information may include a speed threshold. The specific condition may include condition 4, which states that the speed of the aerial UE 100 exceeds the speed threshold. The aerial UE 100 can derive its own speed, for example, based on positioning information.

[0080] Conditional information may include a power threshold. Specific conditions may include condition 5, which states that the received power from a non-serving cell exceeds the power threshold. If the received power from a non-serving cell exceeds the power threshold in the aviation UE 100, there is a high probability that the aviation UE 100 will cause uplink interference to that non-serving cell. Therefore, by limiting transmission when the received power from a non-serving cell exceeds the power threshold, it becomes easier to avoid causing uplink interference to the non-serving cell.

[0081] The specific conditions may include condition 6, which states that the aviation UE 100 initiates a specific uplink transmission. For example, the aviation UE 100 may always control (limit) the uplink transmission power when initiating SDT.

[0082] In step S1, the aviation UE100 may receive broadcast information (e.g., SIB) from a non-serving cell. The specific conditions may include condition 7, which states that the broadcast information received from the non-serving cell includes a transmit power limit notice.

[0083] Aircraft UE 100 may determine in step S2 that a specific condition has been met when any one of conditions 1 to 7 is met. Alternatively, Aircraft UE 100 may determine in step S2 that a specific condition has been met when two or more predetermined combinations of conditions 1 to 7 are met (i.e., when the AND condition is met).

[0084] (3.2) Specific Examples of Operation Based on the operation described above, the first to third examples of operation according to this embodiment will be described.

[0085] (3.2.1) First Operation Example In the first operation example, the gNB200 broadcasts SDT transmit power control information that the aviation UE100 applies under specific conditions. This transmit power information is applied by the aviation UE100 when the RRC is inactive. This transmit power information makes it possible to limit the transmit power when the aviation UE100 transmits SDT data (i.e., reduce the transmit power).

[0086] The specific conditions include, for example, at least one of the following: the highest quality (i.e., currently camped) cell or SSB matches the designated cell or SSB; the altitude of the aerial UE100 exceeds a threshold; the moving speed of the aerial UE100 exceeds a threshold; the received power from non-serving cells exceeds a threshold; or the aerial UE100 initiates SDT.

[0087] Figure 11 shows a first example of operation of the mobile communication system 1 according to this embodiment.

[0088] In step S11, the aircraft UE100 is in an RRC inactive state.

[0089] In step S12, the gNB200 broadcasts transmit power control information (transmit power control parameters) for the SDT. The transmit power control information for the SDT may also be the transmit power setting for the SDT. The aviation UE100 receives the transmit power control information for the SDT. The power control parameters are at least one of the following: information indicating the maximum transmit power for the aviation UE100 (P-Max), information indicating the spectrum emission requirements that the aviation UE100 must satisfy, and a variable (α) applied to the formula for calculating the uplink transmit power.

[0090] In the illustrated example, the aviation UE 100 receives transmit power control information for SDT from a serving cell. However, the aviation UE 100 may also receive transmit power control information for SDT from a non-serving cell. If the aviation UE 100 receives transmit power control information for SDT from multiple non-serving cells, it may adopt (select) the parameter that results in the lowest transmit power from among the received transmit power control information.

[0091] In step S12, the gNB200 may broadcast condition information (condition setting) indicating specific conditions for applying the transmit power control information for SDT. The specific conditions may be any of the following conditions:

[0092] - The highest quality (currently camped) SSB or cell matches the specified SSB or cell. For example, Aviation UE100 may determine that a specific condition is met if the currently highest quality SSB matches the SSB index specified by gNB200.

[0093] - The altitude of aircraft UE100 has exceeded the threshold. Aircraft UE100 may determine that a specific condition has been met if its current altitude exceeds the threshold set by gNB200.

[0094] - The movement speed of aircraft UE100 has exceeded a threshold. Aircraft UE100 may determine that a specific condition has been met if its current movement speed exceeds a threshold set by gNB200.

[0095] - The received power from a non-serving cell (e.g., the reference signal received power (RSRP)) exceeds a threshold. The aviation UE 100 may determine that a specific condition is met when the received power (RSRP) from a non-serving cell exceeds a threshold set by the gNB 200. Here, the non-serving cell may be a specific cell designated by the gNB 200. For example, the non-serving cell may be a cell that corresponds to a list of specific cell identifiers broadcast from a serving cell.

[0096] The above thresholds and / or cell / SSB identifiers may be set (broadcast) from the serving cell or from a non-serving cell.

[0097] - Aircraft UE100 initiates SDT. Aircraft UE100 may always determine that certain conditions are met when initiating SDT.

[0098] In step S13, the aviation UE 100, which is in an RRC inactive state, determines whether or not to start SDT. The aviation UE 100 may decide to start SDT in response to the generation of uplink data. Furthermore, the aviation UE 100 may decide to start SDT only if the amount of the uplink data is less than the amount set by network 5 (gNB 200).

[0099] If it is determined that SDT should be started (step S13: YES), in step S14, the aviation UE 100 determines whether or not specific conditions are met.

[0100] If it is determined that specific conditions are met (step S14: YES), in step S15, the aviation UE 100 applies the transmit power control information received in step S12. Then, in step S16, the aviation UE 100 transmits SDT data to the gNB 200 (serving cell) applying the transmit power control information received in step S12. The gNB 200 receives the uplink data transmitted by SDT. The SDT procedure is as described above.

[0101] On the other hand, if it is determined that certain conditions are not met (step S14: NO), in step S16, the aviation UE 100 transmits SDT data to the gNB 200 (serving cell) without applying the transmit power control information received in step S12. In this case, the aviation UE 100 may transmit SDT data applying the power control information (nr-NS-PmaxListAerial-r18) introduced in release 18 of the 3GPP standard.

[0102] Thus, according to the first example of operation, the aviation UE 100 can reduce the impact on system capacity by suppressing interference to non-serving cells caused by the SDT data transmission to a certain level or less (within an acceptable range) by transmitting SDT data in accordance with the transmit power control information received in step S12.

[0103] (3.2.2) Second Operation Example In the first operation example described above, if certain conditions are met, the aviation UE 100 transmits SDT data to the gNB 200 (serving cell) applying the transmit power control information received in step S12. In contrast, in the second operation example, if certain conditions are met, the aviation UE 100 refrains from executing the SDT (cancels it).

[0104] Figure 12 shows a second example of operation of the mobile communication system 1 according to this embodiment. Explanations of operations similar to those described above will be omitted to avoid repetition.

[0105] In step S21, the aircraft UE100 is in an RRC inactive state.

[0106] In step S22, the gNB200 broadcasts condition information (condition setting) indicating specific conditions for applying the transmit power control information for SDT. The specific conditions are as described above.

[0107] In step S23, the aircraft UE 100, which is in an RRC inactive state, determines whether or not to start SDT. The determination in step S24 may be incorporated into step S23.

[0108] In step S24, the aircraft UE100 determines whether or not specific conditions are met.

[0109] If it is determined that the specific conditions are not met (step S24: NO), in step S25, the aviation UE 100 transmits SDT data to the gNB 200 (serving cell).

[0110] On the other hand, if it is determined that certain conditions are met (step S24: YES), in step S26, the aviation UE 100 refrains from executing the SDT (cannot execute it). In this case, the aviation UE 100 may start the RRC Resume procedure and transition to the RRC Connected state in order to transmit data.

[0111] Thus, according to the second example of operation, by refraining from (canceling) the implementation of SDT in accordance with the above conditions, the aircraft UE100 can reduce the interference to non-serving cells caused by SDT to a certain level or less (acceptable range) and reduce the impact on system capacity.

[0112] (3.2.3) Third Operation Example In the third operation example, if the aviation UE100 receives a notification in broadcast information from a non-serving cell, it reduces the transmit power of the SDT or refrains from performing the SDT. The broadcast information from a non-serving cell is either a System Information Block (SIB) or a Master Information Block (MIB). The MIB is included in the SSB.

[0113] Assuming that the notification is provided in the SIB, the aviation UE 100 may attempt to receive the SIB from a non-serving cell depending on whether the specific conditions described above are met. Normally, the aviation UE 100 is not required to receive the SIB from a non-serving cell, but may do so if the specific conditions are met.

[0114] Figure 13 shows a third example of operation of the mobile communication system 1 according to this embodiment. For operations similar to those described above, redundant explanations will be omitted.

[0115] In step S31, the aircraft UE100 is in an RRC inactive state.

[0116] In step S32, the gNB200a (serving cell) may broadcast transmit power control information for SDT and / or condition information indicating specific conditions. The UE100 may receive the broadcast information.

[0117] In step S33, the aircraft UE 100 in the RRC inactive state may decide whether or not to start SDT.

[0118] In step S34, the aviation UE 100 may determine whether or not a specific condition is met. If it is determined that the specific condition is not met (step S34: NO), in step S35, the aviation UE 100 may transmit data using SDT.

[0119] If it is determined that certain conditions are met (step S34: YES), in step S36, the aviation UE 100 attempts to receive the SIB of the non-serving cell. In step S37, the aviation UE 100 determines whether the SIB (or MIB in the SSB) received from the non-serving cell contains an interference mitigation notice. The interference mitigation notice may be information instructing that interference mitigation measures be taken (e.g., 1-bit information). The interference mitigation notice may include the RSRP threshold of the non-serving cell. The aviation UE 100 may perform the processing in step S38 if the RSRP measurement value of the non-serving cell exceeds the threshold. The interference mitigation notice may include an offset value to reduce the transmission power. The aviation UE 100 may reduce the uplink transmission power by the offset amount when transmitting SDT data.

[0120] If the SIB (or MIB in SSB) received from a non-serving cell does not contain an interference reduction notification (step S37: NO), in step S35, the aviation UE 100 may transmit data using SDT.

[0121] On the other hand, if the SIB (or MIB in SSB) received from a non-serving cell contains an interference reduction notice, in step S38, the aviation UE 100 reduces the uplink transmit power when performing SDT (the above transmit power parameters may be applied), or refrains from performing SDT.

[0122] (4) Other Embodiments The operation according to the above embodiment may be applied to a normal UE 100 that is not an aerial UE 100. That is, the operation according to the above embodiment is not limited to an aerial UE 100, but may be applied to a normal UE 100.

[0123] The above-described operation flows can be performed not only independently, but also in combination of two or more operation flows. For example, some steps of one operation flow may be added to another operation flow, or some steps of one operation flow may be replaced with some steps of another operation flow. It is not necessary to execute all steps in each flow; only some steps may be executed. Furthermore, the order of steps in each flow may be changed as appropriate.

[0124] In the embodiments and examples described above, an example in which the base station is an NR base station (gNB) was described, but the base station may also be an LTE base station (eNB) or a 6G base station. Furthermore, the base station may also be a relay node such as an IAB (Integrated Access and Backhaul) node. The base station may also be a DU of an IAB node. Furthermore, UE100 may be an MT (Mobile Termination) of an IAB node. That is, UE100 may be a terminal function unit (a type of communication module) for the base station to control a relay device that performs signal relay. Such a terminal function unit is referred to as an MT. Examples of multi-transmission architectures (MTs) include IAB-MT, NCR (Network Controlled Repeater)-MT, and RIS (Reconfigurable Intelligent Surface)-MT.

[0125] Furthermore, the term "network node" primarily refers to a base station, but may also refer to a core network device or a part of a base station (CU, DU, or RU). Additionally, a network node may consist of a combination of at least a part of the core network device and at least a part of a base station.

[0126] A program may be provided that causes a computer to execute each process performed by the UE100 or gNB200. The program may be recorded on a computer-readable medium. Using a computer-readable medium, it is possible to install the program on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transient recording medium. The non-transient recording medium is not particularly limited, but may be a recording medium such as a CD-ROM and / or DVD-ROM. Alternatively, the circuits that execute each process performed by the UE100 or gNB200 may be integrated, and at least a part of the UE100 or gNB200 may be configured as a semiconductor integrated circuit (chipset, SoC: System on a chip).

[0127] The functions realized by UE100 or gNB200 may be implemented in a circuit or processing circuit, including a general-purpose processor, application processor, integrated circuit, ASICs (Application Specific Integrated Circuits), CPU (a Central Processing Unit), conventional circuitry, and / or a combination thereof, programmed to realize the described functions. A processor, including transistors and / or other circuitry, is considered a circuit or processing circuit. A processor may be a programmed processor that executes a program stored in memory. In this specification, circuitry, unit, and means are hardware programmed to realize or execute the described functions. The hardware may be any hardware disclosed herein, or any hardware known to be programmed to perform or execute the functions described herein. If the hardware is a processor that is considered to be of the type of circuit, the circuit, means, or unit is a combination of hardware and software used to constitute the hardware and / or processor.

[0128] The phrases “based on” and “depending on / in response to” as used in this disclosure do not mean “based solely on” or “in response solely” unless otherwise specified. “Based on” means both “based solely on” and “at least partially on.” Similarly, “depending” means both “at least partially on” and “at least partially on.” The terms “include,” “comprise,” and variations thereof do not mean that they include only the listed items, but may include only the listed items or may include additional items in addition to the listed items. Furthermore, the term “or” as used in this disclosure is not intended to mean exclusive OR. Additionally, any reference to elements using designations such as “first,” “second,” etc., as used in this disclosure does not generally limit the quantity or order of those elements. These designations may be used herein as a convenient way to distinguish between two or more elements. Therefore, references to the first and second elements do not imply that only two elements may be adopted therein, or that the first element must precede the second element in any way. In this disclosure, where articles are added by translation, such as a, an, and the in English, these articles shall be plural unless it is clearly indicated from the context that they are not.

[0129] Although the embodiments have been described in detail above with reference to the drawings, the specific configuration is not limited to those described above, and various design changes can be made without departing from the gist of the invention.

[0130] This application claims priority to U.S. Provisional Application No. 63 / 698721 (filed September 25, 2024), the entirety of which is incorporated into the specification of this application.

[0131] (5) Additional notes: Features of the above-described embodiments are noted below.

[0132] - Appendix 1 A communication method performed by an aviation user device in a mobile communication system, comprising: receiving broadcast information from a network node to be used for transmission restriction on a specific uplink transmission performed by the aviation user device in a radio resource control (RRC) idle state or RRC inactive state; determining, based on the broadcast information, whether or not specific conditions for performing the transmission restriction on the specific uplink transmission have been met; and, in response to the determination that the specific conditions have been met, performing the transmission restriction on the specific uplink transmission in the RRC idle state or RRC inactive state.

[0133] - Appendix 2 The communication method described in Appendix 1, wherein the specified uplink transmission is a small data transmission (SDT) in which the aircraft user device transmits uplink data to the network while the RRC remains inactive.

[0134] - Appendix 3 The communication method described in Appendix 1, wherein the specified uplink transmission is a physical random access channel (PRACH) transmission in which the aviation user device in the RRC idle state or the RRC inactive state transmits a random access preamble to the network.

[0135] - Appendix 4 The communication method according to any one of Appendix 1 to 3, wherein the broadcast information includes power control information, and the transmission restriction controls the uplink transmission power in the specific uplink transmission based on the power control information.

[0136] - Appendix 5 The communication method described in Appendix 4, wherein the power control information includes power control parameters for limiting the uplink transmission power in the specified uplink transmission.

[0137] - Appendix 6 The communication method described in any of Appendix 1 to 5, wherein the transmission restriction is to refrain from performing the specified uplink transmission when the specified conditions are met.

[0138] - Appendix 7 The broadcast information is a communication method described in any of Appendix 1 to 6, which includes conditional information indicating the specific conditions.

[0139] - Appendix 8 The communication method described in any of Appendix 1 to 7, which includes the condition that the aircraft user device is in flight.

[0140] - Appendix 9 The communication method according to any one of Appendix 6 to 8, wherein the condition information includes information specifying a cell or synchronization signal block (SSB), and the specific condition includes the condition that the cell or SSB selected by the aerial user device matches the specified cell or SSB.

[0141] - Appendix 10 The communication method described in Appendix 6, wherein the condition information includes an altitude threshold, and the specific condition includes the condition that the altitude of the aircraft user device exceeds the altitude threshold.

[0142] - Appendix 11 The communication method according to Appendix 6, wherein the condition information includes a speed threshold, and the specific condition includes the condition that the moving speed of the aircraft user device exceeds the speed threshold.

[0143] - Appendix 12 The communication method described in Appendix 6, wherein the condition information includes a power threshold, and the specific condition includes the condition that the received power from a non-serving cell exceeds the power threshold.

[0144] - Appendix 13 The communication method described in any of Appendix 1 to 3, wherein the specified condition includes the condition that the aircraft user device initiates the specified uplink transmission.

[0145] - Appendix 14 The communication method according to any one of the appendices 1 to 13, wherein the aviation user device receives the broadcast information from a non-serving cell, and the specific condition includes the condition that the broadcast information received from the non-serving cell includes a transmission power limit notice.

[0146] - Appendix 15 An aerial user device for use in a mobile communication system, comprising: a receiving unit that receives broadcast information from a network node used for transmission restriction on a specific uplink transmission performed by the aerial user device in a radio resource control (RRC) idle state or RRC inactive state; and a control unit that determines, based on the broadcast information, whether or not a specific condition for performing the transmission restriction on the specific uplink transmission has been met, wherein the control unit determines that the specific condition has been met, and the aerial user device performs the transmission restriction on the specific uplink transmission in the RRC idle state or RRC inactive state.

[0147] - Appendix 16 A network node used in a mobile communication system, comprising a transmitting unit that transmits broadcast information used for transmission restrictions on specific uplink transmissions performed by an aviation user device when the Radio Resource Control (RRC) is idle or RRC is inactive.

[0148] 1: Mobile communication system 5: Network 10: RAN 20: CN 100: UE (Aeronautical UE) 110: Receiving unit 120: Transmitting unit 130: Control unit 140: Wireless communication unit 200a, 200b: gNB 210: Transmitting unit 220: Receiving unit 230: Control unit 240: Network communication unit 241: Transmitting unit 242: Receiving unit 250: Wireless communication unit 300: AMF / UPF

Claims

1. A communication method performed by an aviation user device in a mobile communication system, comprising: receiving broadcast information from a network node to be used for transmission restriction on a specific uplink transmission performed by the aviation user device in a radio resource control (RRC) idle state or RRC inactive state; determining, based on the broadcast information, whether or not specific conditions for performing the transmission restriction on the specific uplink transmission have been met; and, in response to the determination that the specific conditions have been met, performing the transmission restriction on the specific uplink transmission in the RRC idle state or RRC inactive state.

2. The communication method according to claim 1, wherein the specified uplink transmission is a small data transmission (SDT) in which the aviation user device transmits uplink data to the network while the RRC remains inactive.

3. The communication method according to claim 1, wherein the specified uplink transmission is a physical random access channel (PRACH) transmission in which the aviation user device in the RRC idle state or the RRC inactive state transmits a random access preamble to the network.

4. The communication method according to any one of claims 1 to 3, wherein the broadcast information includes power control information, and the transmission restriction controls the uplink transmission power in the specific uplink transmission based on the power control information.

5. The communication method according to claim 4, wherein the power control information includes power control parameters for limiting the uplink transmission power in the specific uplink transmission.

6. The communication method according to any one of claims 1 to 3, wherein the transmission restriction refrains from performing the specified uplink transmission when the specified conditions are met.

7. The communication method according to any one of claims 1 to 3, wherein the broadcast information includes conditional information indicating the specific conditions.

8. The communication method according to any one of claims 1 to 3, wherein the specific condition includes the condition that the aircraft user device is in flight.

9. The communication method according to claim 7, wherein the condition information includes information specifying a cell or synchronization signal block (SSB), and the specific condition includes the condition that the cell or SSB selected by the aerial user device matches the specified cell or SSB.

10. The communication method according to claim 7, wherein the condition information includes an altitude threshold, and the specific condition includes the condition that the altitude of the aircraft user device exceeds the altitude threshold.

11. The communication method according to claim 7, wherein the condition information includes a speed threshold, and the specific condition includes the condition that the moving speed of the aerial user device exceeds the speed threshold.

12. The communication method according to claim 7, wherein the condition information includes a power threshold, and the specific condition includes the condition that the received power from a non-serving cell exceeds the power threshold.

13. The communication method according to any one of claims 1 to 3, wherein the specific condition includes the condition that the aircraft user device initiates the specific uplink transmission.

14. The communication method according to claim 1, wherein the aviation user device receives the broadcast information from a non-serving cell, and the specific condition includes the condition that the broadcast information received from the non-serving cell includes a transmission power limit notice.

15. Air user equipment for use in a mobile communication system, comprising: a receiving unit that receives broadcast information from a network node for use in restricting transmission of a specific uplink transmission performed by the air user equipment in a radio resource control (RRC) idle state or RRC inactive state; and a control unit that determines, based on the broadcast information, whether or not specific conditions for performing the transmission restriction on the specific uplink transmission have been met, wherein the control unit determines that the specific conditions have been met, and the air user equipment performs the transmission restriction on the specific uplink transmission in the RRC idle state or RRC inactive state.

16. A network node used in a mobile communication system, comprising a transmitting unit that transmits broadcast information used for transmission restrictions on specific uplink transmissions performed by an aviation user device when the Radio Resource Control (RRC) is idle or RRC is inactive.

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