Communication control method, user device, mobile communication system, chipset, and program

Abstract

The present invention provides a communication control method, user device, mobile communication system, chipset, and program that can avoid interference in random access procedures. [Solution] A communication control method for use in a cellular communication system, comprising the step of a network node transmitting parameters used in a random access procedure (RACH parameters for unmanned aerial vehicles (UAVs)) to a user device. The parameters are specific to user devices located at an altitude above a predetermined threshold.

Description

[[Technical Field]]

[0001] The present disclosure relates to a communication control method, a user equipment, a mobile communication system, a chipset, and a program. [[Background Art]]

[0002] In the specifications of 3GPP (The Third Generation Partnership Project) (registered trademark; the same applies hereinafter), which is a standardization project for mobile communication systems, aerial UEs (Aerial UEs) are defined (for example, Non-Patent Document 1 and Non-Patent Document 2). For example, an aerial UE can report altitude and report position information including vertical velocity and horizontal velocity. Through such specifications, 3GPP appropriately supports communication with aerial UEs flying in the sky. [[Prior Art Documents]] [[Non-Patent Documents]]

[0003] [[Non-Patent Document 1]] 3GPP TS 36.300 V17.1.0 (2022-6) [[Non-Patent Document 2]] 3GPP TS 36.331 V17.1.0 (2022-6) [[Summary of the Invention]]

[0004] A communication control method according to one aspect is a communication control method for a mobile communication system. The communication control method comprises a step in which a network node (or a network apparatus) transmits, to a user equipment, a parameter used in a random access procedure. The parameter is a parameter dedicated to user equipment located at an altitude equal to or higher than a predetermined threshold. [[Brief Description of the Drawings]]

[0005] [Figure 1] Figure 1 is a diagram illustrating a configuration example of the mobile communication system according to the first embodiment. [Figure 2] Figure 2 is a diagram showing an example configuration of a UE (User Equipment) according to the first embodiment. [Figure 3] Figure 3 is a diagram showing an example configuration of a gNB (base station) according to the first embodiment. [Figure 4] Figure 4 is a diagram showing an example of the configuration of a protocol stack related to the user plane according to the first embodiment. [Figure 5] Figure 5 is a diagram showing an example of the configuration of a protocol stack related to the control plane according to the first embodiment. [Figure 6] Figure 6 is a diagram showing an example of a cell configuration according to the first embodiment. [Figure 7] Figure 7 is a diagram illustrating an example of operation according to the first embodiment. [Modes for carrying out the invention]

[0006] This disclosure aims to avoid interference in random access procedures.

[0007] 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.

[0008] [First Embodiment]

[0009] (Configuration of mobile communication systems) Figure 1 is a diagram showing the configuration of a mobile communication system according to the first embodiment. The mobile communication system 1 conforms to the 5th Generation System (5GS) of the 3GPP standard. In the following explanation, 5GS will be used as an example, but the mobile communication system may also have at least a portion of the LTE (Long Term Evolution) system applied to it. The mobile communication system may also have at least a portion of the 6th Generation (6G) system applied to it.

[0010] The mobile communication system 1 comprises User Equipment (UE) 100, a 5G radio access network (NG-RAN) 10, and a 5G core network (5GC) 20. Hereafter, NG-RAN 10 may be simply referred to as RAN 10, and 5GC 20 may be simply referred to as core network (CN) 20.

[0011] 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 smartphones) and / or a tablet terminal, a notebook PC, a communication module (including a communication card or chipset), a sensor or device attached to a sensor, a vehicle or device attached to a vehicle (Vehicle UE), or an aircraft or device attached to an aircraft (Aerial UE).

[0012] NG-RAN10 includes base stations (referred to as "gNBs" in 5G systems) 200. The gNBs 200 are interconnected via the Xn interface, which is an inter-base station interface. Each gNB 200 manages one or more cells. The gNB 200 performs wireless communication with UEs 100 that have established a connection with its own cell. The gNB 200 has radio resource management (RRM) functions, user data routing functions (hereinafter simply referred to as "data"), 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 the UE 100. One cell belongs to one carrier frequency (hereinafter simply referred to as "frequency").

[0013] Furthermore, the gNB200 can also connect to the EPC (Evolved Packet Core), which is the core network of LTE. LTE base stations (eNB: evolved Node B) can also connect to the 5GC20. LTE base stations and the gNB200 can also be connected via an inter-base station interface.

[0014] The 5GC20 includes the AMF (Access and Mobility Management Function) and the UPF (User Plane Function) 300. The AMF performs various mobility controls for the UE100. The AMF manages the mobility of the UE100 by communicating with it using NAS (Non-Access Stratum) signaling. The UPF controls data transfer. The AMF and UPF are connected to the gNB200 via the NG interface, which is the base station-core network interface.

[0015] Figure 2 shows an example configuration of UE100 (user device) according to the first embodiment. UE100 comprises 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 that performs wireless communication with gNB200.

[0016] 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.

[0017] 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.

[0018] The control unit 130 performs various types of control and processing in the UE 100. Such processing includes processing of each layer described later. 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 / decoding and the like on baseband signals. The CPU executes programs stored in the memory to perform various types of processing. Note that the control unit 130 may perform each process or each operation in the UE 100 in each embodiment described below.

[0019] Figure 3 is a diagram showing the configuration of the gNB 200 (base station) according to the first embodiment. The gNB 200 includes a transmission unit 210, a reception unit 220, a control unit 230, and a backhaul communication unit 250. The transmission unit 210 and the reception unit 220 constitute a wireless communication unit that performs wireless communication with the UE 100. The backhaul communication unit 250 constitutes a network communication unit that performs communication with the CN 20.

[0020] The transmission unit 210 performs various types of transmission under the control of the control unit 230. The transmission unit 210 includes an antenna and a transmitter. The transmitter converts a baseband signal (transmission signal) output from the control unit 230 into a wireless signal and transmits the wireless signal from the antenna.

[0021] The reception unit 220 performs various types of reception under the control of the control unit 230. The reception unit 220 includes an antenna and a receiver. The receiver converts a wireless signal received by the antenna into a baseband signal (reception signal) and outputs the baseband signal to the control unit 230.

[0022] The control unit 230 performs various control and processing in the gNB200. Such processing includes processing in each layer described later. 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 for 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. In each of the embodiments shown below, the control unit 230 may perform each processing or operation in the gNB200.

[0023] The backhaul communication unit 250 is connected to an adjacent base station via the Xn interface, which is an inter-base station interface. The backhaul communication unit 240 is connected to the AMF / UPF300 via the NG interface, which is an inter-base station-core network interface. The gNB200 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 fronthaul interface.

[0024] Figure 4 shows the configuration of the protocol stack for the user plane's wireless interface that handles data.

[0025] The user plane radio interface protocol consists of 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.

[0026] The PHY layer performs encoding / decoding, modulation / demodulation, antenna mapping / demapping, and resource mapping / demapping. Data and control information are transmitted between the UE100's PHY layer and the gNB200's PHY layer via a physical channel. The UE100's PHY layer receives downlink control information (DCI) transmitted from the gNB200 over the physical downlink control channel (PDCCH). Specifically, the 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 the gNB200 has a CRC parity bit added, which is scrambled by the RNTI.

[0027] The MAC layer performs data priority control, retransmission processing using Hybrid Automatic Repeat request (HARQ), and random access procedures. Data and control information are transmitted between the MAC layer of the UE100 and the MAC layer of the gNB200 via the transport channel. The MAC layer of the 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 the UE100.

[0028] 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 UE100's RLC layer and the gNB200's RLC layer via a logical channel.

[0029] The PDCP layer performs header compression / decompression, encryption / decryption, etc.

[0030] 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.

[0031] Figure 5 shows the configuration of the protocol stack of the wireless interface of the control plane that handles signaling (control signals).

[0032] The control plane's wireless interface protocol stack includes an RRC (Radio Resource Control) layer and a NAS (Non-Access Stratum) layer, instead of the SDAP layer shown in Figure 4.

[0033] 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.

[0034] The NAS, located above the RRC layer, handles session management and mobility management, among other things. NAS signaling is transmitted between the UE100's NAS and the AMF300's NAS. The UE100 also has application layers in addition to the wireless interface protocol. Layers below the NAS are called AS (Access Stratum).

[0035] (UAV) Here, we will describe the unmanned aerial vehicle (UAV: Unmanned Aerial Vehicle or Uncrewed Aerial Vehicle; hereinafter, "unmanned aerial vehicle" may be referred to as "UAV") according to the first embodiment.

[0036] A UAV generally refers to an unmanned aerial vehicle such as a drone. However, in the first embodiment, a UE located at an altitude above (or exceeding) a predetermined threshold is called a UAV. A UAV may be a UE capable of wireless communication with the gNB200 while flying unmanned in the air like an unmanned aerial vehicle. Alternatively, a UAV may be installed on an unmanned aerial vehicle. Alternatively, a UAV may be installed on a manned aircraft. For example, a UE owned by a user on board an aircraft while the aircraft is flying at an altitude above a predetermined threshold may also be a UAV. A UAV may be a UAV UE. Alternatively, a UAV may be an aerial UE. A UAV may be used to distinguish it from a UE used on the ground. However, if no particular distinction is made, a UAV may be included in UE as an example of a UE. In this case, UAVs and UEs may be collectively referred to as UEs. The example configuration of UE100 shown in Figure 2 may represent an example configuration of a UAV.

[0037] 3GPP has established the following provisions to support aerial UE (Aircraft Unification) functionality:

[0038] Firstly, a flying UE can report its altitude. For example, a flying UE can report its altitude when it is above or below a certain threshold. At this time, the flying UE can also report its position information. This position information may include the horizontal and vertical velocity of the flying UE.

[0039] Secondly, the LTE system network (E-UTRAN) can request the flight UE to report flight path information. Flight path information represents waypoints (how-through point information or point information) along the flight UE's route. The flight path information may include a large number of waypoints. Waypoints are represented as three-dimensional positional information. The flight UE may report time information (timestamps) for each waypoint in the flight path information.

[0040] Thirdly, whether or not a flying UE is supported (or whether or not it is permitted to function as a flying UE) is included in the user's subscription information. In the LTE system, the HSS (Home Subscriber Server) stores subscriber information for each user. Whether or not a flying UE is supported is included in the subscriber information. This subscriber information is transmitted from the HSS to the eNB, which is the base station of the LTE system, under the control of the MME (Mobility Management Entity). The eNB can then determine whether or not the UE is permitted to function as a flying UE.

[0041] Fourth, Event H1 and Event H2 can be used as trigger conditions for the measurement report. Event H1 represents the event condition when the altitude of the flying UE exceeds a threshold. On the other hand, Event H2 represents the event condition when the altitude of the flying UE falls below a threshold. Whether or not these event conditions are met is determined using altitude, hysteresis value, offset value, and threshold.

[0042] The 3GPP regulations in this way assume that flight UEs (i.e., UAVs) will be used with LTE systems.

[0043] Meanwhile, 3GPP has begun discussions on introducing UAVs into NR (New Radio). Regarding UAVs, 3GPP has agreed on the use of the aforementioned Event H1 and Event H2, reporting of the UAV's altitude, position, and speed, and reporting of its flight path plan.

[0044] (Ground cells and aerial cells) For example, let's consider a case where ground-based cells and aerial cells coexist within the network. Figure 6 shows an example of a cell configuration illustrating this case.

[0045] As shown in Figure 6, the mobile communication system 1 includes a ground cell and an air cell. In the example shown in Figure 6, the ground cells are formed by gNB200-T1 and gNB200-T2, and the air cell is formed by gNB200-U. In Figure 6, in the ground cell, UE100-1 to 100-4 communicate wirelessly with gNB200-T1 and 200-T2, and in the air cell, UAV150-1 and 150-2 communicate wirelessly with gNB200-U.

[0046] Here, in order for UE100-1 to 100-4 to properly conduct radio communication in ground cells and UAV150-1 and 150-2 to properly conduct radio communication in air cells, the following two scenarios are assumed.

[0047] The first scenario involves allocating a dedicated frequency to the airborne cell, with different frequencies being used for the ground cell and the airborne cell. In the first scenario, for example, radio communication by UAV150-1 and 150-2 and radio communication by UE100-1 to 100-4 are conducted on different frequencies, thus making it possible to avoid interference between the two radio communications.

[0048] On the other hand, the second scenario is one in which the same frequency (or the same frequency range) is used for both ground-based cells and aerial cells. In the second scenario, since the frequency is shared between ground-based cells and aerial cells, it is not necessary to increase frequency resources. Therefore, the second scenario allows for the efficient use of frequency resources.

[0049] (Communication control method according to the first embodiment) Wireless communication using UAV150s presents a unique problem specific to UAVs: it is more susceptible to interference than wireless communication using ground-based UE100s. For example, consider the case where UAV150-1 and 150-2 (hereinafter referred to as UAV150 when UAV150-1 and UAV150-2 are not distinguished) are performing uplink communication, as shown in Figure 6. In such a case, the wireless signal transmitted from the UAV150 may reach not only the serving cell and its adjacent cells, but also over a wider area. If the ground-based UE100 uses the same frequency as the UAV150, the signal from the UAV150 may interfere with the signal from the ground-based UE100. In future discussions within 3GPP, it is expected that various interference avoidance measures will be taken for UAV150s in an RRC-connected state.

[0050] On the other hand, even when a UAV150 performs a random access procedure, if a ground-based UE simultaneously performs a random access procedure using the same frequency, interference may occur, similar to the case described above.

[0051] However, there is currently no workaround for the interference caused by the UAV150 executing random access procedures.

[0052] Therefore, the objective of the first embodiment is to avoid interference in random access procedures.

[0053] Therefore, in the first embodiment, we will describe an example in which the parameters used in the random access procedure (hereinafter sometimes referred to as "RACH" parameters) are parameters specific to the UAV150. Specifically, the base station (e.g., gNB200) transmits the parameters used in the random access procedure to the user equipment (e.g., UE100 or UAV150). Here, these parameters are specific to user equipment (e.g., UAV150) located at an altitude above a predetermined threshold.

[0054] Thus, in the first embodiment, the gNB200 can set RACH parameters specifically for the UAV150 for the UAV150. Therefore, when the UAV150 executes a random access procedure, it becomes possible to appropriately set, for example, the transmit power of the random access preamble and the number of retransmissions of the random access preamble. Such settings make it possible to avoid interference to the UE100 caused by the UAV150 executing a random access procedure.

[0055] (Examples of parameters used in random access procedures) Here, we will explain some examples of parameters used in random access procedures.

[0056] Random access procedures are performed when an RRC idle UE100 performs initial access to the network, when an RRC inactive UE executes the RRC Connection Resume procedure, or when the UE100 executes the RRC Connection Re-establishment procedure. Through random access procedures, the UE100 can establish upstream synchronization with the gNB200 (or cell).

[0057] Firstly, among the parameters used in random access procedures are those used when transmitting the PRACH preamble. The PRACH preamble is the signal that the UE100 transmits first in a random access procedure. These parameters are used by performing the following transmission control on the PRACH preamble.

[0058] In other words, the UE100 first sets values ​​for predetermined variables (such as the preamble transmit counter, preamble power ramping counter, and preamble power ramping step). Of these predetermined variables, the preamble transmit counter is set using the PRACH transmit maximum count parameter (preambleTransMax). The PRACH transmit maximum count parameter represents the maximum number of PRACH preamble transmissions. Also, of the predetermined variables, the preamble power ramping step is set using the transmit power ramping step parameter (powerRampingStep). The transmit power ramping step parameter is a parameter that is incremented each time the PRACH preamble is retransmitted.

[0059] Next, UE100 sets the preamble receive target power (PREAMBLE_RECEIVED_TARGET_POWER) of the RACH preamble using the predetermined variables and the preamble receive target power parameter (preambleReceivedTargetPower). Since this preamble receive target power is the target receive power on the gNB200 side, UE100 calculates the transmit power of the PRACH preamble by calculating the path loss to the gNB200. UE100 then transmits the PRACH preamble with the calculated transmit power.

[0060] As described above, parameters used when transmitting a PRACH preamble include, for example, the PRACH transmission maximum number parameter (preambleTransMax), the transmit power ramping step parameter (powerRampingStep), and the preamble received target power parameter (preambleReceivedTargetPower).

[0061] Secondly, there are parameters used in random access procedures that are used when resending the PRACH preamble. The parameters used for sending the PRACH preamble, as described above, are also used when resending the PRACH preamble. Furthermore, there is a parameter called the backoff time that is used when resending the PRACH preamble. The backoff time represents, for example, the time until the PRACH preamble is resent. The backoff time parameter is set as follows: That is, if UE100 receives a Random Access Response (RAR) (Msg2) containing a MAC sub PDU with a backoff instruction after sending the PRACH preamble, UE100 sets the preamble backoff variable (PREAMBLE_BACKOFF). UE100 sets the value of the value contained in the BI field of the MAC sub PDU multiplied by the scaling factor (SCALING_FACTOR_BI) as the preamble backoff variable. The backoff time parameter is set using a random number between "0" and the preamble backoff variable.

[0062] As described above, parameters used when retransmitting the PRACH preamble include, for example, the PRACH transmission maximum number parameter (preambleTransMax), the transmit power ramping step parameter (powerRampingStep), the preamble received target power parameter (preambleReceivedTargetPower), and the backoff time parameter (backoff time).

[0063] Thirdly, there are parameters used in the random access procedure that are used when UE100 receives a random access response (Msg2). One example of a parameter used when receiving a random access response is the RAR receive window parameter (ra-ResponseWindow). The RAR receive window parameter is a parameter that represents, for example, the time window in which the random access response is monitored. If UE100 does not receive a random access response within the time window indicated by the RAR receive window parameter, it retransmits the PRACH preamble until the backoff time has elapsed. On the other hand, if UE100 receives a random access response within the time window indicated by the RAR receive window parameter, it stops the RAR receive window parameter.

[0064] The PRACH transmission maximum count parameter (preambleTransMax), the transmit power ramping step parameter (powerRampingStep), the preamble received target power parameter (preambleReceivedTargetPower), and the RAR receive window parameter (ra-ResponseWindow) are included in the information element (RACH-ConfigGeneric). RACH-ConfigGeneric is an information element included in the system information (SIB1) broadcast from the gNB200. RACH-ConfigGeneric is used to identify the parameters used in random access procedures.

[0065] (Example of operation according to the first embodiment) Next, an example of operation according to the first embodiment will be described.

[0066] Figure 7 is a diagram illustrating an example of operation according to the first embodiment.

[0067] As shown in Figure 7, in step S10, the gNB200 sends RACH parameters specific to the UAV150.

[0068] Firstly, the RACH parameter specific to the UAV150 is linked to information representing the airspace. This information may be a predetermined threshold for identifying the airspace. This predetermined threshold is used to identify whether the UE100 is in the air or on the ground, and is, for example, an altitude threshold. If there is only one predetermined threshold, two layers, "airspace" and "ground," can be constructed depending on whether the UE100 is higher or lower than that threshold. There may be two or more predetermined thresholds; for example, if there are two, three layers can be constructed: "high altitude," "low altitude," and "ground." Alternatively, the information representing the airspace may be information representing the state in which the UE100 is located in the "airspace" (for example, "airspace"). This linkage indicates that the RACH parameter is used when the UE100 (i.e., the UAV150) is located in the airspace.

[0069] Secondly, the RACH parameter specific to the UAV150 may be at least one parameter included in the information element (RACH-ConfigGeneric) described above. Specifically, it may be any of the following:

[0070] (A1) PRACH transmission maximum number parameter (preambleTransMax)

[0071] (A2) Transmit power ramping step parameter (powerRampingStep)

[0072] (A3) Preamble Received Target Power Parameter

[0073] (A4) RAR Receive Window Parameters (ra-ResponseWindow) For example, the gNB200 can set the preambleReceivedTargetPower parameter, which is specific to the UAV150, to a lower value than the preambleReceivedTargetPower parameter for the ground UE100. This makes it possible to lower the transmission power of the PRACH preamble transmitted from the UAV150 to a lower value than the transmission power of the PRACH preamble transmitted from the ground UE100. This also makes it possible to avoid interference when random access procedures are executed on the UAV150. Other parameters can also be set to lower (or smaller) values ​​than the parameters for the ground UE100 to avoid interference when random access procedures are executed on the UAV150.

[0074] Furthermore, the RACH parameter specific to the UAV150 may also be a backoff time parameter. Alternatively, the RACH parameter specific to the UAV150 may be a parameter representing the upper limit of the backoff time. As mentioned above, the backoff time itself uses a random number ranging from "0" to the preamble backoff variable (PREAMBLE_BACKOFF), but by setting an upper limit on the random number, it is possible to prevent the backoff time from being set to be longer than necessary. This prevents, for example, the backoff time when the PRACH preamble is retransmitted from the UAV150 from being set to be longer than necessary, thus preventing the PRACH preamble from being retransmitted from the UAV150 for an unnecessarily long time, and thus avoiding interference when random access procedures are executed on the UAV150. Alternatively, the RACH parameter specific to the UAV150 may be a parameter representing the maximum value of the backoff time. The maximum value of the backoff time indicates that the backoff time will be set to a specified maximum value rather than using a random number. Alternatively, the RACH parameter specific to the UAV150 could be a parameter representing a lower limit of the backoff time (e.g., "0"). This lower limit ensures that the randomly generated backoff time is always "0". This allows, for example, the gNB200 to control the UAV150 so that it must wait a certain amount of time before retransmitting the PRACH preamble, thereby avoiding interference with the ground UE100's random access procedure.

[0075] Thus, the parameter values ​​included in the RACH parameters specific to the UAV150 will be different from the parameter values ​​for the ground-based UE100. This allows them to be RACH parameters specific to the UAV150.

[0076] Furthermore, the above-mentioned (A1) to (A4), and the backoff time parameter may be transmitted by broadcast using system information (SIB).

[0077] In step S11, the UE100 executes a random access procedure using RACH parameters specific to the UAV150 at an altitude above a predetermined threshold. The altitude of the UE100 may be measured by an altitude sensor installed on the UE100. The altitude of the UE100 may be measured by a distance sensor (such as radar or lidar) installed on the UE100. The altitude may be expressed as sea level. The altitude may be expressed as elevation. The altitude may be expressed as height from the ground.

[0078] Furthermore, gNB200 may transmit some of the RACH parameters specifically for the UAV150 as described above. In this case, UE100 may apply some of the RACH parameters specifically for the UAV150, and for other RACH parameters that have not been transmitted, apply the ground (or conventional) RACH parameters, and then execute the random access procedure.

[0079] [Other embodiments] Each of 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.

[0080] 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.

[0081] 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).

[0082] 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 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).

[0083] The phrases “based on” and “depending on / in response to” used in this disclosure do not mean “based solely on” or “depending solely on” unless otherwise specified. “Based on” means both “based solely on” and “at least partially on.” Similarly, “depending on” means both “at least partially on” and “at least partially on.” The terms “include,” “comprise,” and variations thereof do not mean that only the listed items are included; they mean that only the listed items may be included, or that additional items may be included in addition to the listed items. Furthermore, the term “or” used in this disclosure is not intended to mean exclusive OR. Additionally, any reference to elements using designations such as “first,” “second,” etc., 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 by the context that they are not.

[0084] Although one embodiment has been described in detail above with reference to the drawings, the specific configuration is not limited to that described above, and various design changes can be made without departing from the gist of the work. Furthermore, it is possible to combine all or part of each embodiment, each operation, each process, and each step, as long as they do not contradict each other.

[0085] This application claims priority to Japanese Patent Application No. 2022-161585 (filed on October 6, 2022), and all of its contents are incorporated into the specification of this application.

[0086] (Note) (Note 1) A communication control method in a mobile communication system, The network node has a step of sending parameters used in a random access procedure to the user device, The aforementioned parameter is a parameter exclusive to user devices located at a height above a predetermined threshold. Communication control method.

[0087] (Note 2) The aforementioned parameters are parameters used by the user device when it transmits the PRACH preamble. The communication control method described in Appendix 1.

[0088] (Note 3) The aforementioned parameters are those used by the user device when retransmitting the PRACH preamble. The communication control method described in Appendix 1 or Appendix 2.

[0089] (Note 4) The aforementioned parameters are parameters used by the user device when receiving a random access response. A communication control method as described in any of Appendix 1 to Appendix 3. [Explanation of Symbols]

[0090] 1: Mobile communication systems 20:5GC 100:UE 110: Receiving unit 130: Control unit 150: UAV 200:gNB 210: Transmitter 230: Control Unit

Claims

1. A communication control method in a mobile communication system, The user device receives parameters related to the event conditions of the measurement report from the network node, The user device determines whether the event condition is met based on the altitude threshold and altitude hysteresis value included in the parameters, The user device transmits the measurement report when the event conditions are met. Communication control method.

2. A user device in a mobile communication system, A receiving unit that receives parameters related to the event conditions of the measurement report from a network node, A control unit that determines whether the event condition is met based on the altitude threshold and altitude hysteresis value included in the parameters, The system includes a transmission unit that transmits the measurement report when the aforementioned event conditions are met. User device.

3. A mobile communication system having user equipment and network nodes, The user device receives parameters related to the event conditions of the measurement report from the network node. The user device determines whether the event condition is met based on the altitude threshold and altitude hysteresis value included in the parameters. The user device transmits the measurement report when the event conditions are met. Mobile communication system.

4. A chipset for a user device in a mobile communication system, Receiving parameters related to the event conditions of the measurement report from the network node, Based on the altitude threshold and altitude hysteresis value included in the aforementioned parameters, it is determined whether or not the event condition is met. The system includes sending the measurement report when the aforementioned event conditions are met. Chipset.

5. In user equipment in a mobile communication system, The process involves receiving parameters related to the event conditions of the measurement report from the network node, A process to determine whether the event condition is met based on the altitude threshold and altitude hysteresis value included in the aforementioned parameters, If the aforementioned event conditions are met, the process of sending the measurement report is executed. program.

Images