Wireless communication system, terminal device, base station, and control method

Abstract

A wireless communication system comprises a base station and a terminal device. The terminal device transmits, to the base station, a first message indicating the characteristics of the terminal device and a second message including a scheduled transmission data amount. The base station receives data in the scheduled transmission data amount from the terminal device that is the sender of the second message and, when the first message satisfies a given condition, disconnects a connection to the terminal device without waiting for reception of a third message that requests disconnection of the connection from the terminal device. The terminal device transmits the data in the scheduled transmission data amount to the base station and, when the first message satisfies a given condition, disconnects a connection to the base station without transmitting the third message to the base station.

Description

Wireless Communication System, Terminal Device, Base Station, and Control Method

[0001] The present invention relates to a wireless communication system, a terminal device, a base station, a control method, and the like. This application claims priority based on Japanese Patent Application No. 2024-169748 filed in Japan on September 30, 2024, the content of which is incorporated herein by reference.

[0002] Conventionally, a wireless communication system including a communication terminal such as a smartphone has been known. For example, Patent Document 1 discloses a wireless communication system in which a communication device notifies a first wireless communication network to which the communication device has been connected that the communication device has been connected to a second wireless communication network due to priority communication.

[0003] International Publication No. 2022 / 208915

[0004] In the method of Patent Document 1, although notification to the first wireless communication network is performed, even when such notification is performed, a process for disconnecting the connection (detach process) is required.

[0005] According to some aspects of the present disclosure, it is possible to provide a wireless communication system, a terminal device, a base station, a control method, and the like that suppress the load at the end of communication.

[0006] One aspect of the present disclosure is a wireless communication system including a base station and a terminal device, wherein the terminal device transmits a first message indicating the characteristics of the terminal device to the base station, transmits a second message including a planned transmission data amount to the base station, the base station receives data of the planned transmission data amount from the terminal device that is the transmission source of the second message, and when the first message satisfies a given condition, disconnects the connection with the terminal device without waiting to receive a third message that is a connection disconnection request from the terminal device, the terminal device transmits data of the planned transmission data amount to the base station, and when the first message satisfies the given condition, disconnects the connection with the base station without transmitting the third message to the base station.

[0007] Other aspects of this disclosure relate to a terminal device, comprising: a wireless communication unit for performing wireless communication with a base station; a transmission data amount determination unit for acquiring a transmission data amount which is the amount of data to be transmitted to the base station; and a transmission data amount determination unit for acquiring the amount of data transmitted to the base station, wherein the wireless communication unit transmits a first message indicating the characteristics of the terminal device to the base station, transmits a second message including the transmission data amount to the base station, and if the transmission data amount determination unit determines that the data of the transmission data amount has been transmitted to the base station and the first message satisfies given conditions, the wireless communication unit disconnects the connection with the base station without transmitting a third message which is a request to disconnect the connection with the base station.

[0008] Further aspects of this disclosure relate to a base station, which includes a wireless communication unit that performs wireless communication with a terminal device, a receiving data amount determination unit that acquires a receiving data amount which is the amount of data to be received from the terminal device, and a received data amount determination unit that acquires the amount of data received from the terminal device, wherein the wireless communication unit receives a first message from the terminal device indicating the characteristics of the terminal device, receives a second message from the terminal device including the receiving data amount, and if the received data amount determination unit determines that it has received the receiving data of the receiving data amount from the terminal device which is the source of the second message, and the first message satisfies given conditions, it disconnects the connection with the terminal device without waiting for the reception of a third message which is a request to disconnect the connection from the terminal device.

[0009] Further aspects of the present disclosure relate to a control method for a wireless communication system including a base station and a terminal device, the method comprising: transmitting a first message from the terminal device to the base station indicating the characteristics of the terminal device; transmitting a second message from the terminal device to the base station including the amount of data to be transmitted; obtaining the amount of data transmitted by the terminal device to the base station after the transmission of the second message; and, if the data of the amount of data to be transmitted has been transmitted from the terminal device to the base station and the first message satisfies a given condition, disconnecting the connection between the base station and the terminal device without transmitting a third message, which is a request to disconnect the connection, from the terminal device to the base station.

[0010] This figure shows an example configuration of a wireless communication system according to this embodiment. This figure shows an example configuration of a base station according to this embodiment. This figure shows an example configuration of a terminal device according to this embodiment. This is a sequence diagram illustrating the communication process when the first message does not satisfy the conditions. This is a sequence diagram illustrating the communication process when the first message satisfies the conditions. This is a sequence diagram illustrating the communication process when the first message satisfies the conditions.

[0011] This embodiment will be described below with reference to the drawings. In the drawings, the same or equivalent elements are denoted by the same reference numerals, and redundant descriptions are omitted. This embodiment described below is not intended to unduly limit the content described in the claims. Furthermore, not all of the configurations described in this embodiment are essential components of this disclosure.

[0012] 1. System Configuration Example Figure 1 shows an example of the wireless communication system 10 of this embodiment. The wireless communication system 10 includes a base station 100 and a terminal device 200. However, the configuration of the wireless communication system 10 is not limited to the example in Figure 1, and various modifications can be made, such as adding configurations not shown or omitting some configurations. For example, the number of base stations 100 included in the wireless communication system 10 is not limited to one, but may be multiple. Also, the number of terminal devices 200 included in the wireless communication system 10 is not limited to one, but may be multiple.

[0013] Base station 100 provides a communication network using a predetermined wireless communication method. The predetermined wireless communication method is, for example, a communication method using a fifth-generation mobile communication system (5G system). Specifically, base station 100 is a base station that applies the NR (New Radio) standard, which is a Radio Access Technology (RAT) for 5G cellular mobile communication systems. Base station 100 is connected to a 5G core network (not shown) in a way that enables information communication. In this embodiment, base station 100 may also perform communication in accordance with communication standards such as LTE (Long Term Evolution) and 4G standards.

[0014] The terminal device 200 is a terminal that performs communication in accordance with communication standards such as 5G, LTE, and 4G. The terminal device 200 is also called UE (User Equipment).

[0015] The terminal device 200 in this embodiment may be a RedCap (Reduced Capability) compatible terminal. RedCap is a standard with some communication functions restricted, intended for use in devices such as wearable devices and IoT (Internet of Things) devices. The restricted communication functions are, for example, some communication functions of NR functions such as band width and MIMO (multiple-input and multiple-output).

[0016] For example, the terminal device 200 in this embodiment is a device capable of communication with reduced functionality compared to a normal terminal (e.g., a smartphone, tablet, laptop computer, etc.). Specifically, the terminal device 200 may be a small sensor configured as an IoT device. In Figure 1, a sensor device such as a surveillance camera is shown as an example of the terminal device 200. However, the terminal device 200 may be a normal terminal that is not a RedCap-compatible terminal, such as a smartphone or tablet.

[0017] Base station 100 is, for example, a wireless base station that supports communication with RedCap-compatible terminals. Base station 100 may be a base station device that only communicates with RedCap-compatible terminals, or it may be a base station device that can communicate with both RedCap-compatible and non-RedCap-compatible terminals. Non-RedCap-compatible terminals are terminals that support communication intended for use with smartphones, tablet devices, etc., and are not subject to the communication function restrictions imposed on RedCap-compatible terminals. For example, if base station 100 supports communication with non-RedCap-compatible terminals, base station 100 may be a wireless base station operated by a telecommunications carrier such as a mobile network operator or a virtual mobile network operator. Hereinafter, RedCap-compatible terminals will also be simply referred to as RedCap terminals. Similarly, non-RedCap-compatible terminals will also be referred to as non-RedCap terminals.

[0018] Figure 2 shows an example configuration of a base station 100. The base station 100 includes a control unit 110 and a wireless communication unit 120. The control unit 110 includes a received data volume determination unit 111, a planned received data volume determination unit 112, and a terminal determination unit 113. However, the configuration of the base station 100 is not limited to the example in Figure 2, and various modifications can be made, such as adding components not shown or omitting some components.

[0019] The control unit 110 of this embodiment can be implemented by predetermined hardware. The hardware may include at least one of a circuit that processes digital signals and a circuit that processes analog signals. For example, the hardware may consist of one or more circuit devices or one or more circuit elements mounted on a circuit board. As the circuit device, an IC (Integrated Circuit) or an FPGA (Field-Programmable Gate Array) may be used. One or more circuit elements may be, for example, a resistor or a capacitor.

[0020] The control unit 110 may be implemented by one or more processors. The base station 100 in this embodiment includes, for example, a memory for storing information and a processor that operates based on the information stored in the memory. The information includes, for example, a program and various types of data. The processor includes hardware. Various types of processors can be applied, such as a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), or a DSP (Digital Signal Processor). The memory may be a semiconductor memory such as SRAM (Static Random Access Memory), DRAM (Dynamic Random Access Memory), or flash memory, or it may be a register. The memory may be a magnetic storage device such as a hard disk drive (HDD), or an optical storage device such as an optical disk drive. For example, the memory stores instructions that can be read by a computer, and the functions of the control unit 110 are realized as processing when the processor executes these instructions. The instructions may be instructions from an instruction set that constitutes a program, or they may be instructions that instruct the hardware circuit of the processor to operate.

[0021] The received data amount determination unit 111 determines the amount of data (hereinafter referred to as received data amount) received by the base station 100 from the terminal device 200 via the wireless communication unit 120. If multiple terminal devices 200 are connected to the base station 100, the received data amount determination unit 111 determines the received data amount for each of the multiple terminal devices 200. The received data amount determination unit 111 may determine the amount of the data (packets) themselves received by the wireless communication unit 120, or it may determine the amount of data from the data received by the wireless communication unit 120 excluding control signals, headers, etc.

[0022] The data amount to be received determination unit 112 determines the amount of data that the base station 100 is expected to receive from the terminal device 200 via the wireless communication unit 120 (hereinafter referred to as the "data amount to be received"). If multiple terminal devices 200 are connected to the base station 100, the data amount to be received determination unit 112 determines the data amount to be received for each of the multiple terminal devices 200. For example, as will be described later, the terminal device 200 may notify the base station 100 of the amount of data it is expected to transmit to the base station 100 before actually starting to transmit the data. The data amount to be received determination unit 112 may acquire the data amount notified by the terminal device 200 as the data amount to be received.

[0023] The terminal determination unit 113 performs a process to determine the characteristics of the terminal device 200. For example, the terminal determination unit 113 determines whether or not the terminal device 200 is a RedCap terminal. Alternatively, the terminal determination unit 113 may determine whether or not the terminal device 200 is a terminal that performs one-way communication from the terminal device 200 to the base station 100 (hereinafter referred to as a one-way communication terminal). Note that a one-way communication terminal here is not limited to a terminal in which all communication is one-way. For example, a one-way communication terminal may perform bidirectional communication of transmission and reception for messages (control data) used at the start of communication, etc., and perform one-way communication of transmission only for actual data (for example, measurement results of sensors described later).

[0024] Details of the processing performed by each part included in the control unit 110 will be described later.

[0025] The wireless communication unit 120 is an interface for communication over a network. The wireless communication unit 120 includes, for example, an antenna, an RF (radiofrequency) circuit, and a baseband circuit. The wireless communication unit 120 may operate according to the control of the control unit 110, or it may include a communication control processor different from the control unit 110. The wireless communication unit 120 performs wireless communication in accordance with communication standards such as 5G and LTE, as described above.

[0026] Figure 3 shows an example configuration of the terminal device 200. The terminal device 200 includes a control unit 210 and a wireless communication unit 220. The control unit 210 includes a data transmission volume determination unit 211 and a data transmission planned volume determination unit 212. However, the configuration of the terminal device 200 is not limited to the example in Figure 3, and various modifications can be made, such as adding components not shown or omitting some components.

[0027] The control unit 210 of this embodiment can be implemented by predetermined hardware. The hardware may include at least one of a circuit for processing digital signals and a circuit for processing analog signals.

[0028] The control unit 210 may be implemented by one or more processors. The terminal device 200 of this embodiment includes, for example, a memory for storing information and a processor that operates based on the information stored in the memory. The information is, for example, a program and various types of data. The processor includes hardware. Various types of processors can be applied, such as a CPU, GPU, DSP, etc. The memory may be a semiconductor memory such as SRAM, DRAM, or flash memory, or it may be a register, a magnetic storage device, or an optical storage device. For example, the memory stores instructions that can be read by a computer, and the functions of the control unit 210 are realized as processing when the processor executes these instructions.

[0029] The transmitted data amount determination unit 211 determines the amount of data (hereinafter referred to as transmitted data amount) transmitted by the terminal device 200 to the base station 100 via the wireless communication unit 220. For example, the transmitted data amount determination unit 211 may determine the transmitted data amount using functions such as buffer status reports.

[0030] The planned data transmission amount determination unit 212 determines the amount of data that the terminal device 200 plans to transmit to the base station 100 via the wireless communication unit 220 (hereinafter referred to as the planned data transmission amount). For example, if the terminal device 200 is a sensor device, the terminal device 200 stores measurement results from the sensor and transmits the measurement results to the base station 100 when certain conditions (such as the passage of a predetermined time or the detection of an anomaly) are met. In this case, the planned data transmission amount determination unit 212 may determine the amount of data stored as the measurement results as the planned data transmission amount.

[0031] Details of the processing performed by each part included in the control unit 210 will be described later.

[0032] The wireless communication unit 220 is an interface for communication over a network. The wireless communication unit 220 includes, for example, an antenna, an RF circuit, and a baseband circuit. The wireless communication unit 220 may operate according to the control of the control unit 210, or it may include a communication control processor different from the control unit 210. The wireless communication unit 220 performs wireless communication in accordance with communication standards such as 5G and LTE, as described above.

[0033] As described above, the wireless communication system 10 according to this embodiment may include a base station 100 and a terminal device 200. The terminal device 200 according to this embodiment transmits a first message to the base station 100 indicating the characteristics of the terminal device 200, and transmits a second message to the base station 100 including the amount of data to be transmitted. The base station 100 receives the data of the amount of data to be transmitted (amount of data to be received) from the terminal device 200, which is the source of the second message, and if the first message satisfies the given conditions, it disconnects the connection with the terminal device 200 without transmitting or receiving a third message, which is a request to disconnect the connection, to the terminal device 200. The terminal device 200 also transmits the data of the amount of data to be transmitted to the base station 100, and if the first message satisfies the given conditions, it disconnects the connection with the base station 100 without transmitting or receiving a third message to the base station 100.

[0034] For example, if the third message is a message sent from the terminal device 200 to the base station 100, the base station 100 will disconnect from the terminal device 200 without waiting to receive the third message, which is a request to disconnect the connection from the terminal device 200. Alternatively, the terminal device 200 may disconnect from the base station 100 without sending the third message to the base station 100.

[0035] Alternatively, if the third message is a message to be sent from base station 100 to terminal device 200, base station 100 will disconnect from terminal device 200 without sending the third message to terminal device 200. Also, terminal device 200 will disconnect from base station 100 without waiting to receive the third message from base station 100.

[0036] According to the method of this embodiment, if the first message satisfies predetermined conditions, at least a portion of the processing related to the termination of communication between the base station 100 and the terminal device 200 can be omitted. Since the first message here is information representing the characteristics of the terminal device 200, the statement that the first message satisfies predetermined conditions can be rephrased as the statement that the terminal device 200 has predetermined characteristics. For example, if the first message includes information indicating that the terminal device 200 is a RedCap terminal, or information indicating that the terminal device 200 is a terminal that performs one-way communication from the terminal device 200 to the base station 100, it is determined that the first message satisfies the given conditions. In this way, it is possible to reduce the processing load on the base station 100 and the terminal device 200 related to the termination of communication by using appropriate conditions.

[0037] The third message here may be, for example, a Deregistration Request Message. In this case, at least the process of sending a Deregistration Request Message from the terminal device 200 to the base station 100 and the process of sending a Deregistration Accept Message from the base station 100 to the terminal device 200 can be omitted in the Deregistration Procedure. When IoT devices are used as terminal devices 200, the number of terminal devices 200 connected to a single base station 100 can be enormous. Therefore, even if the load of a single Deregistration Procedure is not that large, if a large number of Deregistration Procedures are required with many terminal devices 200, the processing load and communication load of the base station 100 can become large. According to the method of this embodiment, the communication load and processing load of the base station 100 can be reduced. Furthermore, the communication load and processing load related to communication with the base station 100 can also be reduced for the terminal device 200. Since the terminal device 200 is small and lightweight, and its processor processing power and battery capacity may be inferior to those of a normal terminal (e.g., a non-RedCap terminal), there is a significant benefit in reducing the burden associated with the deregistration procedure.

[0038] Furthermore, 5G standards and similar standards specify processes other than sending and receiving deregistration request messages and deregistration acceptance messages as part of the deregistration procedure (for example, processes between the base station 100 and the core network). In this embodiment, these processes may or may not be omitted. If they can be omitted, the load on the base station 100 can be further reduced.

[0039] Furthermore, the method of this embodiment is not limited to being applied to the wireless communication system 10, but may also be applied to a base station 100 or a terminal device 200 that constitutes the wireless communication system 10. For example, the terminal device 200 is a terminal device 200 that performs wireless communication with the base station 100, and includes a wireless communication unit 220 that performs wireless communication, a transmission data amount determination unit 212 that acquires the transmission data amount which is the amount of data to be transmitted to the base station 100, and a transmission data amount determination unit 211 that acquires the amount of data transmitted to the base station 100. The wireless communication unit 220 transmits a first message indicating the characteristics of the terminal device 200 to the base station 100, and transmits a second message including the transmission data amount to the base station 100. If the wireless communication unit 220 determines that the transmission data amount determination unit 211 has transmitted the data of the transmission data amount to the base station 100, and the first message satisfies a given condition, it disconnects the connection with the base station 100 without transmitting or receiving a third message which is a connection disconnection request to the base station 100. For example, the wireless communication unit 220 disconnects from the base station 100 without transmitting the third message to the base station 100. Alternatively, the wireless communication unit 220 disconnects from the base station 100 without waiting for the reception of the third message from the base station 100.

[0040] Furthermore, the method of this embodiment may be applied to the following base station 100. The base station 100 includes a wireless communication unit 120 that performs wireless communication with a terminal device 200, a received data amount determination unit 112 that acquires the amount of data to be received from the terminal device 200, and a received data amount determination unit 111 that acquires the amount of data received from the terminal device 200. The wireless communication unit 120 receives a first message from the terminal device 200 that indicates the characteristics of the terminal device 200, and receives a second message from the terminal device 200 that includes the amount of data to be received. If the received data amount determination unit 111 determines that the wireless communication unit 120 has received the data of the amount of data to be received from the terminal device 200, which is the source of the second message, and the first message satisfies a given condition, the wireless communication unit 120 disconnects the connection with the terminal device 200 without sending or receiving a third message, which is a request to disconnect the connection, to the terminal device 200. For example, the wireless communication unit 120 disconnects the connection with the terminal device 200 without waiting to receive the third message from the terminal device 200. Alternatively, the wireless communication unit 120 disconnects from the terminal device 200 without sending a third message to the terminal device 200.

[0041] Furthermore, some or all of the processing performed by the wireless communication system 10, base station 100, and terminal device 200 in this embodiment may be implemented by a program. For example, the program may be a program that implements the processing performed by the control unit 110 of the base station 100 and / or the control unit 210 of the terminal device 200. The processing performed by the control unit 110 and the processing performed by the control unit 210 will be described later with reference to Figures 4-6.

[0042] The program according to this embodiment can be stored in a non-temporary information storage medium (information storage device), which is a medium readable by a computer. The information storage medium can be implemented as, for example, an optical disc, a memory card, an HDD, or a semiconductor memory. The semiconductor memory is, for example, ROM. The control unit 110 and the like perform various processing according to this embodiment based on the program stored in the information storage medium. That is, the information storage medium stores a program that causes the computer to function as the control unit 110 and the like. The computer is a device that includes an input device, a processing unit, a storage unit, and an output unit. Specifically, the program according to this embodiment is a program that causes the computer to execute each of the steps described later using Figures 4 to 6.

[0043] Furthermore, the method of this embodiment may be applied to a control method for a wireless communication system 10 including a base station 100 and a terminal device 200, which includes the following steps: The control method for the wireless communication system 10 includes: transmitting a first message indicating the characteristics of the terminal device 200 from the terminal device 200 to the base station 100; transmitting a second message including the amount of data to be transmitted from the terminal device 200 to the base station 100; obtaining the amount of data (amount of transmitted data, amount of received data) transmitted by the terminal device 200 to the base station 100 after the transmission of the second message; and, if the data of the amount of data to be transmitted has been transmitted from the terminal device 200 to the base station 100 and the first message satisfies given conditions, disconnecting the connection between the base station 100 and the terminal device 200 without transmitting or receiving a third message which is a request to disconnect the connection between the base station 100 and the terminal device 200. Not transmitting or receiving the third message between the base station 100 and the terminal device 200 means that the terminal device 200 does not transmit the third message to the base station 100, or that the base station 100 does not transmit the third message to the terminal device 200.

[0044] 2. Processing flow Next, the processing of the base station 100 and the terminal device 200 in this embodiment will be described. In the following, when the transmission and reception of the third message are not omitted, an example in which the third message is a message transmitted from the terminal device 200 to the base station 100 will be described. However, as described above, the third message may be transmitted from the base station 100 to the terminal device 200.

[0045] 2.1 Example of executing communication termination sequence (detach process) FIG. 4 is a sequence diagram for explaining communication processing executed when a first message satisfying a predetermined condition is not transmitted from the terminal device 200 to the base station 100. The communication processing here includes the period from the start to the end of communication between the terminal device 200 and the base station 100.

[0046] When this process is started, first, in step S101, the terminal device 200 transmits a message (Msg1) to the base station 100 using the RACH (Random Access Channel).

[0047] For example, before the processing in step S101, the base station 100 may periodically transmit notification information. The notification information here is, for example, a synchronization signal block (SSB), and may include information about the base station 100. The terminal device 200 may execute a process of scanning the SSB (cell search) and acquire base station information based on the PSS (Primary SS), SSS (Secondary SS), PBCH, etc. included in the notification information. In step S101, the terminal device 200 transmits the first message based on the acquired base station information. The first message may be a RACH - preamble.

[0048] In step S102, the terminal device 200 transmits a registration request message (Registration Request Message) to the base station 100. In step S103, the base station 100 transmits a registration acceptance message (Registration Accept Message) to the terminal device 200 as a response to the registration request message. Note that the registration procedure including the transmission and reception of the registration request message and the registration acceptance message is defined in standards such as the 5G standard and is widely known, so detailed description is omitted.

[0049] When the registration procedure is completed, communication between the base station 100 and the terminal device 200 becomes possible. Although omitted in FIG. 4, after the completion of the registration procedure, a PDU session establishment procedure may be executed.

[0050] In step S104, the transmission scheduled data amount determination unit 212 of the terminal device 200 determines the transmission scheduled data amount that the terminal device 200 plans to transmit to the base station 100. The transmission scheduled data amount determination unit 212 may determine the transmission scheduled data amount based on the data amount that is the sensor output, or may determine the transmission scheduled data amount based on the data amount accumulated in the buffer for transmission. Then, the wireless communication unit 220 of the terminal device 200 transmits a message (second message) including the determined transmission scheduled data amount to the base station 100 in advance. The reception scheduled data amount determination unit 112 of the base station 100 performs a process of acquiring the transmission scheduled data amount received via the wireless communication unit 120 as the reception scheduled data amount.

[0051] In step S105, the wireless communication unit 220 of the terminal device 200 starts transmitting data based on the control of the control unit 210. Specifically, when the terminal device 200 is a sensor device, the wireless communication unit 220 transmits data representing the measurement result by the sensor to the base station 100.

[0052] If the transmission of data representing the measurement results is completed, in step S106, the terminal device 200 sends a Deregistration Request Message to the base station 100. In step S107, the base station 100 sends a Deregistration Accept Message to the terminal device 200 as a response to the Deregistration Request Message. The deregistration procedure, including the sending and receiving of the Deregistration Request Message and the Deregistration Accept Message, is defined in standards such as the 5G standard and is widely known, so a detailed explanation is omitted.

[0053] As described above, in this embodiment, if the base station 100 and terminal device 200 have not transmitted or received a first message that satisfies a given condition, specifically if the terminal device 200 does not have a given characteristic, communication may be possible in a manner that does not omit the unregistration procedure, similar to the conventional method. In this process, after the transmission and reception of the necessary data is completed, a process for disconnecting communication (in a narrow sense, an unregistration procedure) is executed in both the base station 100 and the terminal device 200 (steps S106 and S107).

[0054] 2.2 RedCap Terminal In the method of this embodiment, if the first message is a message notifying that the terminal device 200 is a RedCap terminal, the base station 100 (wireless communication unit 120) may disconnect the connection with the RedCap terminal without waiting for the reception of the third message. That is, the first message that satisfies the given conditions may be a message that includes information indicating that the terminal device 200 is a RedCap terminal. In this way, when the terminal device 200 is a RedCap terminal, it is possible to reduce the processing load on the base station 100 and the terminal device 200 by omitting at least a part of the communication termination sequence. This will be explained in detail below.

[0055] Figure 5 is a sequence diagram illustrating an example of communication processing performed between a base station 100 and a terminal device 200, which is executed when a first message satisfies a given condition.

[0056] When this process begins, in step S201, the terminal device first sends a message (Msg1) to the base station 100 using RACH. For example, terminal device 200 may use the message sent here as the first message to notify that terminal device 200 is a RedCap terminal. For example, in 5G, the Early Indication function is known in RACH's Msg1 to notify that the UE is a RedCap terminal. Terminal device 200 may use this Early Indication function to send a first message to terminal device 200 that includes information indicating that terminal device 200 is a RedCap terminal.

[0057] In this case, as described above, the first message satisfies the given conditions. For example, when the message in step S201 is received, the terminal determination unit 113 of the base station 100 may determine whether the terminal device 200 is a RedCap terminal based on the first message, and if the terminal device 200 is a RedCap terminal, it may determine that the given conditions are satisfied.

[0058] The processing in steps S202-S205 is the same as the processing described above using Figure 4. Specifically, in step S202, the terminal device 200 sends a Registration Request Message to the base station 100. In step S203, the base station 100 sends a Registration Accept Message to the terminal device 200 as a response to the Registration Request Message.

[0059] In step S204, the planned transmission data amount determination unit 212 of the terminal device 200 determines the amount of data that the terminal device 200 is scheduled to transmit to the base station 100. The wireless communication unit 220 of the terminal device 200 then pre-transmits a second message containing the determined amount of data to transmit to the base station 100. The planned reception data amount determination unit 112 of the base station 100 processes the data to transmit that it has received via the wireless communication unit 120 to obtain the amount of data to receive. In step S205, the wireless communication unit 220 of the terminal device 200 starts transmitting data based on the control unit 210. Specifically, if the terminal device 200 is a sensor device, the wireless communication unit 220 transmits data representing the measurement results of the sensor to the base station 100.

[0060] When the transmission and reception of an amount of data equivalent to the planned transmission amount (or planned reception amount) is completed, as shown in Figure 5, the base station 100 and the terminal device 200 disconnect the connection between the base station 100 and the terminal device 200 without sending or receiving a message regarding the termination of communication.

[0061] Specifically, the transmitted data volume determination unit 211 of the terminal device 200 determines the amount of data transmitted to the base station 100 via the wireless communication unit 220. For example, 5G provides functions for understanding the status of data transmission and reception, such as buffer status reports. The transmitted data volume determination unit 211 may use these functions to determine the amount of data that has been transmitted. When the amount of data transmitted reaches the amount of data to be transmitted, the transmitted data volume determination unit 211 determines that the reporting of the measurement results by the sensor is complete. If the terminal device 200 has sent a message indicating that it is a RedCap terminal as the first message, it disconnects communication with the base station 100 without sending the deregistration request message shown in step S106 of Figure 4.

[0062] Meanwhile, the received data amount determination unit 111 of the base station 100 determines the amount of data received from the terminal device 200 via the wireless communication unit 120. In the process shown in Figure 5, as described above, the terminal determination unit 113 of the base station 100 determines, based on the message received in step S201, that the terminal device 200 is a RedCap terminal, that is, that the first message satisfies the given conditions. Therefore, the received data amount determination unit 111 determines that the terminal device 200 has completed reporting the measurement results from the sensor when the amount of received data reaches the amount of data to be received. In this case, the base station 100 executes a process to disconnect communication with the terminal device 200 without waiting for a deregistration request message from the terminal device 200.

[0063] Thus, in this embodiment, if the first message satisfies the conditions, at least a portion of the communication termination process can be omitted. The base station 100 and the terminal device 200 branch whether to execute the process shown in Figure 4 or the process shown in Figure 5 based on whether the first message satisfies the conditions (step S101 or S102) (branching whether to execute steps S106-S107).

[0064] For example, if the terminal device 200 is a RedCap terminal, as shown in the measurement results of the sensor described above, the terminal device 200 only needs to be able to unilaterally transmit predetermined data to the base station 100, and the frequency of data transmission from the base station 100 to the terminal device 200 is considered to be low. Therefore, when the data transmission amount determination unit 211 determines that the data amount to be transmitted has been transmitted, the wireless communication unit 220 of the terminal device 200 disconnects the connection with the base station 100 without sending a third message. In this way, with a RedCap terminal, the probability of problems occurring even if the terminal device 200 unilaterally disconnects communication is low.

[0065] Similarly, the wireless communication unit 120 of the base station 100 may disconnect from the terminal device 200 without waiting for the reception of the third message if the data reception amount determination unit 112 determines that it has received data equal to the amount of data to be transmitted (or received) from the terminal device 200. As described above, in a RedCap terminal, once the transmission of predetermined data to the base station 100, such as the transmission of sensor measurement results, is complete, there is a low probability that data transmission from the terminal device 200 to the base station 100 will be immediately required. Therefore, even if the base station 100 unilaterally disconnects communication without waiting for the reception of the third message, there is a low probability that problems will arise.

[0066] As described above, the method of this embodiment makes it possible to determine the characteristics of the terminal device 200 based on the first message and then simplify the sequence related to communication termination if it is not necessary.

[0067] As shown in Figure 5, the terminal device 200 may send a fourth message to the base station 100 requesting a connection to the base station 100 after sending the first message (step S201) and before sending the second message (step S204). The base station 100 may send a fifth message to the base station 100 in response to the fourth message, accepting the connection of the terminal device 200. In this way, it becomes possible to establish a connection between the base station 100 and the terminal device 200 using the fourth and fifth messages, and then disconnect the connection without sending or receiving a third message (communication termination request).

[0068] Specifically, the fourth message may be a Registration Request message, and the fifth message may be a Registration Accept message. In this way, it becomes possible to establish a connection between the base station 100 and the terminal device 200 through the registration procedure (transition to the registered state), and to disconnect the connection (transition to the unregistered state) without sending or receiving the third message.

[0069] 2.3 One-Way Communication Terminal In the method of this embodiment, if the first message is a message notifying that one-way communication will be performed from the terminal device 200 to the base station 100, the base station 100 (wireless communication unit 120) may disconnect the connection with the terminal device 200 without waiting for the reception of the third message. That is, the first message that satisfies the given conditions may be a message that includes information indicating that the terminal device 200 is a one-way communication terminal. In this way, when the terminal device 200 is a one-way communication terminal, it is possible to reduce the processing load on the base station 100 and the terminal device 200 by omitting at least a part of the communication termination sequence. This will be explained in detail below.

[0070] Figure 6 is a sequence diagram illustrating an example of communication processing performed between a base station 100 and a terminal device 200, which is executed when a first message satisfies a given condition.

[0071] When this process begins, in step S301, the terminal device first sends a message (Msg1) to the base station 100 using RACH (Random Access Channel). As described above, the process in step S301 corresponds to the RACH procedure specified for 5G, etc.

[0072] In step S302, the terminal device 200 transmits a message (first message) notifying the base station 100 that it will perform one-way communication from the terminal device 200 to the base station 100. In this case, as described above, the first message satisfies the given conditions. For example, upon receiving the message in step S302, the terminal determination unit 113 of the base station 100 may determine whether the terminal device 200 is a one-way communication terminal based on the first message, and if the terminal device 200 is a one-way communication terminal, it may determine that the given conditions are satisfied.

[0073] Figure 6 shows an example of notifying that one-way communication will be performed using a message different from Msg1 using RACH, but the method of this embodiment is not limited to this. For example, the message notifying one-way communication may be Msg1 as shown in step S301. Alternatively, the message notifying one-way communication may be sent from the terminal device 200 to the base station 100 after the registration procedure (steps S303-S304 described later) is completed.

[0074] The processing in steps S303-S306 is the same as the processing described above using Figure 4. Specifically, in step S303, the terminal device 200 sends a Registration Request Message to the base station 100. In step S304, the base station 100 sends a Registration Accept Message to the terminal device 200 as a response to the Registration Request Message.

[0075] In step S305, the planned transmission data amount determination unit 212 of the terminal device 200 determines the planned transmission data amount that the terminal device 200 plans to send to the base station 100. The wireless communication unit 220 of the terminal device 200 then sends a second message containing the determined planned transmission data amount to the base station 100. The planned reception data amount determination unit 112 of the base station 100 processes the planned transmission data amount received via the wireless communication unit 120 to be acquired as the planned reception data amount. In step S306, the wireless communication unit 220 of the terminal device 200 starts transmitting data based on the control unit 210. Here, as described above, one-way communication from the terminal device 200 to the base station 100 is performed.

[0076] Once the transmission of the necessary data is complete, as shown in Figure 6, the base station 100 and the terminal device 200 disconnect the connection between the base station 100 and the terminal device 200 without sending or receiving any messages regarding the termination of communication.

[0077] Specifically, the data transmission volume determination unit 211 of the terminal device 200 determines the amount of data transmitted to the base station 100 via the wireless communication unit 220. The data transmission volume determination unit 211 determines that one-way communication by the terminal device 200 is complete when the amount of data transmitted reaches the planned data transmission volume. If the terminal device 200 has transmitted a message indicating that it is a one-way communication terminal as the first message, it disconnects communication with the base station 100 without sending the deregistration request message shown in step S106 of Figure 4.

[0078] Meanwhile, the received data amount determination unit 111 of the base station 100 determines the amount of data received from the terminal device 200 via the wireless communication unit 120. In the process shown in Figure 6, as described above, the terminal determination unit 113 of the base station 100 determines, based on the message received in step S302, that the terminal device 200 is a one-way communication terminal, that is, that the first message satisfies the given conditions. Therefore, the received data amount determination unit 111 determines that the terminal device 200 has completed one-way communication to the base station 100 when the amount of received data reaches the amount of data to be received. In this case, the base station 100 executes a process to disconnect communication with the terminal device 200 without waiting for the reception of a deregistration request message from the terminal device 200.

[0079] Thus, in this embodiment, if the first message satisfies the conditions, at least a portion of the communication termination process can be omitted.

[0080] If the terminal device 200 is a one-way communication terminal, it is sufficient for the terminal device 200 to unilaterally transmit predetermined data to the base station 100, and it is considered that no data transmission from the base station 100 to the terminal device 200 occurs, except for control signals, etc. Therefore, when the wireless communication unit 220 of the terminal device 200 determines that the data amount to be transmitted has been transmitted by the data transmission amount determination unit 211, it disconnects the connection with the base station 100 without sending a third message. In this way, with a one-way communication terminal, the probability of problems occurring even if the terminal device 200 unilaterally disconnects the communication is low.

[0081] Similarly, the wireless communication unit 120 of the base station 100 may disconnect the connection with the terminal device 200 without waiting for the reception of the third message if the data amount determination unit 112 determines that it has received data equal to the amount of data to be transmitted (data amount to be received) from the terminal device 200. As described above, in a one-way communication terminal, once the transmission of predetermined data to the base station 100 is complete, there is a low probability that data transmission from the terminal device 200 to the base station 100 will be immediately required. Therefore, even if the communication is unilaterally disconnected from the base station 100 without waiting for the reception of the third message, there is a low probability that problems will arise.

[0082] As described above, the method of this embodiment makes it possible to determine the characteristics of the terminal device 200 based on the first message and then simplify the sequence related to communication termination if it is not necessary.

[0083] 2.4 The above processing combinations describe the processing when the first message does not satisfy the given conditions (Figure 4), the processing when the first message satisfies the given conditions and the terminal device 200 is a RedCap terminal (Figure 5), and the processing when the first message satisfies the given conditions and the terminal device 200 is a one-way communication terminal (Figure 6).

[0084] The base station 100 according to this embodiment may be capable of performing all the processes shown in Figures 4-6, for example. For example, when the base station 100 is connected to a terminal device 200 which is a RedCap terminal, it performs the above-described process with the terminal device 200 using Figure 5; when it is connected to a terminal device 200 which is a one-way communication terminal, it performs the above-described process with the terminal device 200 using Figure 6; and when it is connected to a terminal device 200 which is neither of the above, it performs the above-described process with the terminal device 200 using Figure 4.

[0085] However, the base station 100 may perform only a portion of the processes shown in Figures 4-6. For example, the base station 100 is a base station dedicated to RedCap terminals and may perform the processes shown in Figure 5 but not the processes shown in Figures 4 and 6. Alternatively, the base station 100 is a base station that does not support RedCap and may perform the processes shown in Figures 4 and 6 but not the processes shown in Figure 5.

[0086] Furthermore, the terminal device 200 may be a terminal that can switch between functioning as a RedCap terminal, a one-way communication terminal, or a terminal that is neither a RedCap terminal nor a one-way communication terminal, depending on the situation. In this case, the terminal device 200 may switch which of the processes shown in Figures 4-6 it executes, depending on which terminal it is functioning as.

[0087] Alternatively, terminal device 200 may always function as a RedCap terminal, performing the process shown in Figure 5, but not having to perform the processes shown in Figures 4 and 6. Furthermore, terminal device 200 may always function as a one-way communication terminal, performing the process shown in Figure 6, but not having to perform the processes shown in Figures 4 and 5.

[0088] Furthermore, various modifications can be made to the operation of the base station 100 and terminal device 200 according to this embodiment.

[0089] Although this embodiment has been described in detail above, it will be readily apparent to those skilled in the art that many modifications are possible without substantially departing from the novel aspects and effects of this embodiment. Therefore, all such modifications are included within the scope of this disclosure. For example, any term that appears at least once in the specification or drawings together with a broader or synonymous term may be replaced with that different term anywhere in the specification or drawings. Furthermore, all combinations of this embodiment and its modifications are also included within the scope of this disclosure. In addition, the configuration and operation of wireless communication systems, base stations, terminal devices, etc., are not limited to those described in this embodiment, and various modifications are possible.

Claims

1. A wireless communication system comprising a base station and a terminal device, wherein the terminal device transmits a first message indicating the characteristics of the terminal device to the base station, and transmits a second message to the base station including the amount of data to be transmitted, the base station receives the data of the amount of data to be transmitted from the terminal device which is the source of the second message, and if the first message satisfies a given condition, disconnects the connection with the terminal device without waiting to receive a third message from the terminal device which is a request to disconnect the connection, and the terminal device transmits the data of the amount of data to be transmitted to the base station, and if the first message satisfies the given condition, disconnects the connection with the base station without transmitting the third message to the base station.

2. A wireless communication system according to claim 1, wherein the terminal device includes a wireless communication unit that performs wireless communication with the base station, and a transmitted data amount determination unit that acquires the amount of data transmitted to the base station after the transmission of the second message, wherein the wireless communication unit disconnects the connection with the base station without transmitting the third message when the transmitted data amount determination unit determines that the data of the planned transmission amount has been transmitted.

3. A wireless communication system according to claim 1, wherein the base station includes a wireless communication unit that performs wireless communication with the terminal device, and a received data amount determination unit that acquires the amount of data received from the terminal device after receiving the second message, and the wireless communication unit disconnects the connection with the terminal device without waiting for the reception of the third message when the received data amount determination unit determines that it has received the data of the planned transmission amount from the terminal device.

4. A wireless communication system according to any one of claims 1 to 3, wherein the base station disconnects the connection with the RedCap terminal without waiting for the reception of the third message if the first message is a message notifying that the terminal device is a RedCap (Reduced Capability) terminal.

5. A wireless communication system according to any one of claims 1 to 3, wherein the base station disconnects the connection with the terminal device without waiting for the reception of the third message if the first message is a message notifying the terminal device to perform one-way communication from the terminal device to the base station.

6. A wireless communication system according to any one of claims 1 to 3, wherein the third message is a Deregistration Request message.

7. A wireless communication system according to any one of claims 1 to 3, wherein the terminal device transmits a fourth message to the base station requesting connection to the base station after transmitting the first message and before transmitting the second message, and the base station transmits a fifth message to the terminal device in response to the fourth message, accepting the connection of the terminal device.

8. A wireless communication system according to claim 7, wherein the fourth message is a Registration Request message and the fifth message is a Registration Accept message.

9. A terminal device comprising: a wireless communication unit for performing wireless communication with a base station; a planned transmission data amount determination unit for acquiring a planned transmission data amount which is the amount of data to be transmitted to the base station; and a transmitted data amount determination unit for acquiring the amount of data transmitted to the base station, wherein the wireless communication unit transmits a first message indicating the characteristics of the terminal device to the base station, transmits a second message including the planned transmission data amount to the base station, and if the transmitted data amount determination unit determines that the data of the planned transmission data amount has been transmitted to the base station, and the first message satisfies a given condition, the terminal device disconnects the connection with the base station without transmitting a third message which is a request to disconnect the connection with the base station.

10. A base station comprising: a wireless communication unit for performing wireless communication with a terminal device; a planned data amount determination unit for acquiring a planned data amount which is the amount of data to be received from the terminal device; and a received data amount determination unit for acquiring the amount of data received from the terminal device, wherein the wireless communication unit receives a first message from the terminal device indicating the characteristics of the terminal device, receives a second message from the terminal device including the planned data amount, and if the received data amount determination unit determines that it has received the data of the planned data amount from the terminal device which is the source of the second message, and the first message satisfies given conditions, it disconnects the connection with the terminal device without waiting for the reception of a third message which is a request to disconnect the connection from the terminal device.

11. A control method for a wireless communication system including a base station and a terminal device, comprising: transmitting a first message from the terminal device to the base station indicating the characteristics of the terminal device; transmitting a second message from the terminal device to the base station including the amount of data to be transmitted; obtaining the amount of data transmitted by the terminal device to the base station after the transmission of the second message; and, if the data of the amount of data to be transmitted has been transmitted from the terminal device to the base station and the first message satisfies a given condition, disconnecting the connection between the base station and the terminal device without transmitting a third message, which is a request to disconnect the connection, from the terminal device to the base station.

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