Terminal device, base station device, control method and computer-readable recording medium for performing random access procedure

Abstract

A terminal device of a mobile communication network that sends a first message containing user data to a base station device during a random access process, when a predetermined condition for transitioning from an inactive state to a connected state is met, sends a first message containing predetermined information to notify the base station device that the terminal device should transition to a connected state; when the predetermined condition is not met, sends a first message that does not contain the predetermined information.

Description

Technical Field

[0001] The present invention relates to a terminal device, a base station device, a control method and a computer-readable recording medium for performing a random access process, and more particularly to an improvement technology for the random access process. Background Art

[0002] In the 3rd Generation Partnership Project (3GPP), standards for wireless communication systems such as Long Term Evolution (LTE) and Fifth Generation (5G) New Radio (NR) are established. In LTE and NR, a random access procedure for the initial connection between a terminal device and a base station device is specified. Regarding the random access procedure, a four-step or two-step communication process is proposed. It should be noted that, hereinafter, the two-step random access procedure is sometimes referred to as "two-step RACH", and the four-step random access procedure is sometimes referred to as "four-step RACH".

[0003] Four-step RACH processing Figure 1A As shown. In the four-step RACH, first, the terminal device (User Equipment, UE) sends a random access (RA) preamble as the first message (Message 1) to the base station device. Here, the base station device is expressed as gNB in ​​the case of NR and as eNB in ​​the case of LTE in one example. It should be noted that the RA preamble is sent using predetermined wireless resources (frequency-time resources). When the base station device detects the RA preamble, it sends the RA response as the second message (Message 2) to the terminal device. Message 2 contains information on the wireless resources to be used in the transmission of the third message (Message 3) that the terminal device should send after receiving Message 2, and the parameters used for signal transmission. In addition, Message 2 contains various information such as the timing advance (TA) for synchronizing the timing of the signal. The terminal device uses the wireless resources and various information specified by the information to send the predetermined information for establishing initial access from the terminal device to the base station device as Message 3. For example, when the terminal device is in the inactive (RRC_Inactive) state, an RRC recovery request (RRCResumeRequest) requesting an instruction to transition to the connected (RRC_Connected) state is included in message 3. In addition, as a response, when the base station device instructs to transition to the connected state, the fourth message (message 4) includes RRCResume indicating the transition to the connected state. Then, the base station device sends message 4 to the terminal device in response to message 3. By performing these processes, an initial connection between the terminal device and the base station device is established.

[0004] then, Figure 1BAn example of processing of a two-step random access procedure. In the two-step RACH, first, the UE sends the above-mentioned RA preamble and predetermined information for establishing initial access as a first message (message A). Then, when the base station device detects the RA preamble, it sends an RA response and a response to the predetermined information for establishing initial access as a second message (message B). For example, when the terminal device is in an inactive state, message A includes RRCResumeRequest requesting an indication of transition to a connected state. In addition, as a response, when the base station device indicates a transition to a connected state, message B includes RRCResume indicating a transition to a connected state. Summary of the invention

[0005] Problems to be solved by the invention

[0006] In 3GPP, a study is being conducted on the transmission and reception of less user data between a base station device and a terminal device in an inactive state without switching to a connected state. 3GPP, RP-190838 states the following: In two-step RACH and four-step RACH, user data is transmitted and received between a terminal device and a base station device while the terminal device is maintained in an inactive state. On the other hand, the base station device cannot determine whether user data should be transmitted and received while the terminal device is maintained in an inactive state or after switching to a connected state. As a result, for example, the base station device causes the terminal device to unnecessarily switch to a connected state through RACH processing with the terminal device, thereby causing an increase in unnecessary signaling messages.

[0007] Means used to solve problems

[0008] The present invention provides a technology for appropriately managing the state of a terminal device when user data is transmitted and received between the terminal device and a base station device during a random access procedure.

[0009] A terminal device according to one embodiment of the present invention comprises a sending unit, which sends a first message containing user data to a base station device during a random access process of a mobile communication network, wherein the terminal device comprises a control unit, which controls the sending unit so that: when a predetermined condition for transitioning from an inactive state to a connected state is met, the first message containing predetermined information is sent, the predetermined information being used to notify the base station device that the terminal device should transition to the connected state; and when the predetermined condition is not met, the first message not containing the predetermined information is sent.

[0010] A base station device according to one embodiment of the present invention is a base station device of a mobile communication network, comprising: a receiving unit, which receives a first message containing user data from a terminal device in an inactive state during a random access process; a first sending unit, which sends a second message as a response to the first message; and a control unit, which controls the first sending unit so that: when the first message contains predetermined information, the second message containing an instruction to transition the terminal device to a connected state is sent, and when the first message does not contain the predetermined information, the second message not containing the instruction is sent.

[0011] A control method according to one embodiment of the present invention is a control method executed by a terminal device of a mobile communication network, wherein:

[0012] The control method comprises a sending step, in which a first message including user data is sent to a base station device during a random access process;

[0013] In the sending step,

[0014] When a predetermined condition for transitioning from the inactive state to the connected state is satisfied, sending the first message including predetermined information for notifying the base station device that the terminal device should transition to the connected state,

[0015] When the predetermined condition is not satisfied, the first message not including the predetermined information is sent.

[0016] A computer-readable recording medium according to one embodiment of the present invention stores a program for causing a computer included in a terminal device of a mobile communication network to send a first message including user data to a base station device during a random access procedure, wherein:

[0017] The program is used to control the terminal device so that:

[0018] When a predetermined condition for transitioning from the inactive state to the connected state is satisfied, sending the first message including predetermined information for notifying the base station device that the terminal device should transition to the connected state,

[0019] When the predetermined condition is not satisfied, the first message not including the predetermined information is sent.

[0020] A control method according to one embodiment of the present invention is a control method executed by a base station device of a mobile communication network, wherein:

[0021] The control method comprises the following steps:

[0022] a receiving step, in which a first message including user data is received from a terminal device in an inactive state during a random access procedure; and

[0023] a sending step, in which a second message is sent as a response to the first message;

[0024] In the sending step,

[0025] When the first message satisfies a predetermined condition, sending the second message including an instruction to make the terminal device transition to a connected state to the terminal device,

[0026] When the first message does not satisfy the predetermined condition, the second message that does not include the instruction is sent to the terminal device.

[0027] A computer-readable recording medium according to one embodiment of the present invention stores a program for controlling a terminal device so that a computer included in a base station device of a mobile communication network executes the following steps:

[0028] In a random access procedure, receiving a first message including user data from the terminal device in an inactive state,

[0029] sending a second message as a response to the first message,

[0030] in,

[0031] When the first message satisfies a predetermined condition, sending the second message including an instruction to make the terminal device transition to a connected state,

[0032] In a case where the first message does not satisfy the predetermined condition, the second message that does not include the indication is sent.

[0033] Effects of the Invention

[0034] According to the present invention, when user data is transmitted and received between a terminal device and a base station device in a random access procedure, the state of the terminal device can be appropriately managed.

[0035] Other features and advantages of the present invention will become apparent from the following description with reference to the accompanying drawings. In the accompanying drawings, the same or similar structures are denoted by the same reference numerals. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings are incorporated in and constitute a part of the specification, illustrate embodiments of the present invention, and together with the description, serve to explain the principles of the present invention.

[0037] Figure 1AThis is a diagram schematically showing the flow of a conventional four-step random access procedure.

[0038] Figure 1B This is a diagram schematically showing the flow of a two-step random access procedure.

[0039] Figure 2 It is a diagram showing a configuration example of a wireless communication system.

[0040] Figure 3 This is a diagram showing an example of the hardware configuration of a terminal device.

[0041] Figure 4 This is a diagram showing an example of a functional structure of a terminal device.

[0042] Figure 5 It is a diagram showing a hardware configuration example of a base station device.

[0043] Figure 6 It is a diagram showing a functional configuration example of a base station apparatus.

[0044] Fig. 7A It is a diagram showing an example of messages transmitted and received in the wireless communication system according to the first embodiment.

[0045] Figure 7B It is a diagram showing an example of messages transmitted and received in the wireless communication system according to the first embodiment.

[0046] Fig. 8A This is a diagram showing an example of a flow of processing executed in the wireless communication system according to the first embodiment.

[0047] Figure 8B This is a diagram showing an example of a process flow executed in the wireless communication system according to the first embodiment.

[0048] Fig.9A It is a diagram showing an example of messages transmitted and received in the wireless communication system according to the second embodiment.

[0049] Fig. 9B It is a diagram showing an example of messages transmitted and received in the wireless communication system according to the second embodiment.

[0050] Fig. 10A This is a diagram showing an example of a process flow executed in the wireless communication system according to the second embodiment.

[0051] Fig. 10B This is a diagram showing an example of a process flow executed in the wireless communication system according to the second embodiment.

[0052] Fig.11AIt is a diagram showing an example of messages transmitted and received in the wireless communication system according to the third embodiment.

[0053] Fig. 11B It is a diagram showing an example of messages transmitted and received in the wireless communication system according to the third embodiment.

[0054] Fig.12 This is a diagram showing an example of a process flow executed by the base station apparatus according to the third embodiment.

[0055] Fig.13A It is a diagram showing an example of messages transmitted and received in the wireless communication system according to the fourth embodiment.

[0056] Fig. 13B It is a diagram showing an example of messages transmitted and received in the wireless communication system according to the fourth embodiment.

[0057] Fig.14A This is a diagram showing an example of a flow of processing executed in the wireless communication system according to the fourth embodiment.

[0058] Fig. 14B This is a diagram showing an example of a flow of processing executed in the wireless communication system according to the fourth embodiment. DETAILED DESCRIPTION

[0059] Hereinafter, the embodiments are described in detail with reference to the accompanying drawings. It should be noted that the following embodiments do not limit the invention involved in the claims, and all combinations of features described in the embodiments are not limited to the content necessary for the invention. Two or more of the multiple features described in the embodiments may also be combined arbitrarily. In addition, the same or similar structures are marked with the same figure numerals, and repeated descriptions are omitted.

[0060] (System Structure)

[0061] Figure 2 The structure example of the wireless communication system involved in this embodiment is shown. In one example, this system is a 5G cellular communication system (mobile communication network). However, this is not limited to this, and this system can be, for example, a subsequent cellular communication system after 5G, or a wireless communication system other than cellular. This system is configured to include a base station device 101 and a terminal device 102. It should be noted that in Figure 2 In order to simplify the description, only one base station device and one terminal device are shown, but the number of these devices is not limited, and of course there may be more base station devices and terminal devices.

[0062] The terminal device 102 according to this embodiment executes Figure 1A or Figure 1B The four-step RACH or two-step RACH shown in the figure establishes a connection with the base station apparatus 101. It should be noted that according to the two-step RACH, the terminal apparatus and the base station apparatus each establish a connection by sending a message only once, so compared with the four-step RACH, the connection between the terminal apparatus and the base station apparatus can be established in a short time.

[0063] In this embodiment, in the RACH process, the base station apparatus and the terminal apparatus perform transmission and reception of a small amount of user data. At this time, for example, if the transmission and reception of user data is completed in the RACH phase, or is completed by a small number of transmissions and receptions, it is not necessary to resume the terminal apparatus from the inactive state to the connected state. On the other hand, for example, in the case of transmitting and receiving a large amount of user data, the terminal apparatus should be resumed from the inactive state to the connected state.

[0064] However, the base station apparatus does not have a mechanism for determining whether it is necessary to transition the terminal apparatus from the inactive state to the connected state. Therefore, the base station apparatus does not instruct the terminal apparatus to restore to the connected state, or instructs the terminal apparatus to restore to the connected state. As a result, the frequency utilization efficiency may be reduced due to unnecessary transmission and reception of signaling messages and unnecessary repetition of RACH processing.

[0065] Therefore, in the wireless communication system according to the present embodiment, in the RACH phase, the terminal device determines whether to transmit and receive user data while maintaining the inactive state or to switch to the connected state in order to transmit and receive user data, and notifies the base station device. Based on the notification, the base station device determines whether to switch the terminal device to the connected state or to maintain the inactive state, and sends a signaling message corresponding to the determined content to the terminal device. Thus, the base station device can appropriately determine whether to switch the terminal device in the inactive state to the connected state, thereby preventing a decrease in frequency utilization efficiency.

[0066] Several embodiments of the structure of an apparatus for performing such processing and the flow of processing are described below. In addition, in the following embodiments, a process of sending a message including predetermined information indicating whether a predetermined condition for transitioning to a connected state is satisfied when a terminal apparatus in an inactive state sends user data to a base station apparatus is described.

[0067] <First Embodiment>

[0068] (Structure of terminal device)

[0069] Figure 3The following is a hardware configuration example of the terminal device 102 according to the present embodiment. In one example, the terminal device 102 includes a processor 301, a ROM 302, a RAM 303, a storage device 304, a communication circuit 305, and a battery 306. In the terminal device 102, for example, the processor 301 executes a program recorded in any one of the ROM 302, the RAM 303, and the storage device 304 to implement each function of the terminal device 102 in the four-step RACH or the two-step RACH. It should be noted that the processor 301 may be one or more processors such as a CPU (central processing unit), an ASIC (application specific integrated circuit), an FPGA (field programmable gate array), and a DSP (digital signal processor).

[0070] The terminal device 102 controls the communication circuit 305 through the processor 301, for example, to communicate with the other party device (for example, the base station device). Figure 3 102 is a schematic diagram showing that the terminal device has one communication circuit 305, but the present invention is not limited thereto. For example, the terminal device 102 may also have a communication circuit for communicating with the base station device 101 and a communication circuit for communicating with a wireless LAN, etc. In addition, the terminal device 102 is provided with a battery 306 such as a rechargeable battery that can be charged and discharged, and the battery 306 is used to transmit data to the terminal device 102. Figure 3 The components of the terminal device 102 shown are supplied with power.

[0071] It should be noted that the terminal device 102 may include dedicated hardware for executing each function, or may execute a part of the functions by hardware and execute the other parts by a computer running a program. Alternatively, all functions may be executed by a computer and a program.

[0072] Next, we will refer to Figure 4 The functional configuration example of the terminal device 102 involved in this embodiment is described. The terminal device 102 has a communication control unit 401, a connection processing unit 402, a user data management unit 403, a state control unit 404, a threshold acquisition unit 405, and a battery control unit 406 as its functions. It should be noted that the terminal device can of course have other functions as a general terminal device, but they are omitted here for the sake of simplicity of description.

[0073] The communication control unit 401 controls the communication performed between the terminal device 102 and the base station device 101 (for example, wireless communication in accordance with the communication standard of 5G). The communication control unit 401, for example, performs various controls for performing communication with the base station device 101. In one example, the communication control unit 401 performs various controls for wireless communication in accordance with the 5G standard. The connection processing unit 402 performs two-step RACH or four-step RACH via the communication control unit 401, thereby establishing a connection with the base station device 101.

[0074] The user data management unit 403 temporarily holds the user data transmitted and received with the base station device 101. The state control unit 404 manages the connection state with the base station device 101, including the idle (RRC_Idle) state, the inactive state, and the connected state. The idle state is a kind of waiting state, in which a connection is not established between the base station device 101 and the terminal device 102, and the context information of the terminal device 102 is not maintained in the base station device 101. The inactive state is also a kind of standby state, in which a connection is not established between the base station device 101 (or a network node that can communicate with the base station device 101) and the terminal device 102, and the base station device 101 and the network node maintain the context information of the terminal device 102. In one example, the terminal device 102 supplies power to the control unit in the inactive state, but does not supply power to the wireless communication unit. In this way, the power consumption of the terminal device 102 can be suppressed. The so-called connected state refers to a state in which the base station device 101 allocates resources to the terminal device 102 and can perform unicast communication.

[0075] The threshold acquisition unit 405 acquires a threshold value for determining whether the state managed by the state control unit 404 should be changed to the connected state. In one example, the threshold acquisition unit 405 may also acquire information about the threshold value from a broadcast signal transmitted by the base station device 101. It should be noted that the threshold acquisition unit 405 may also acquire information about the threshold value through an individual message when the connection with the base station device 101 is cut off and the state managed by the state control unit 404 is changed to the inactive state. The battery control unit 406 controls operations including charging and discharging of the battery 306 possessed by the terminal device 102. In addition, the battery control unit 406 can acquire the remaining power of the battery 306.

[0076] The state control unit 404 controls the state of the terminal device 102 based on information from at least one of the connection processing unit 402 , the user data management unit 403 , the threshold acquisition unit 405 , and the battery control unit 406 .

[0077] For example, when there is user data stored in the user data management unit 403, and when the state managed by the state control unit 404 is an inactive state or an idle state, the connection processing unit 402 performs four-step RACH or two-step RACH. At this time, when the state managed by the state control unit 404 is an idle state, the state is changed to a connected state, and the communication control unit 401 communicates the user data after the state is changed. On the other hand, when the state managed by the state control unit is an inactive state, user data smaller than a predetermined size among the user data stored in the user data management unit 403 can be included in a message and the message is sent. In addition, when the terminal device 102 is in a connected state, the communication control unit 401 transmits and receives the user data stored in the user data management unit 403 in the resources allocated by the base station device 101.

[0078] In addition, the state control unit 404 determines whether to attempt to transition from the inactive state or the idle state to the connected state based on the amount of user data stored in the user data management unit 403. Then, when the state control unit 404 determines that the state should transition to the connected state, it executes four-step RACH or two-step RACH. For example, in the inactive state, when the amount of user data is small to the extent that the user data can be transmitted by message 3 and message A in the RACH stage, the state control unit 404 can determine not to transition to the connected state.

[0079] In one example, the terminal device 102 may determine that the condition for transitioning to the connected state is satisfied when it is determined that the amount of user data held by the user data management unit 403 cannot be transmitted by only a predetermined number of messages 3. For example, when the terminal device 102 has user data to be transmitted, if the amount of user data is small, it does not transition to the connected state to transmit the user data, but determines to transmit the user data by one or more messages 3.

[0080] In another example, the terminal device 102 can predict the traffic pattern based on the history of user data sent to the base station device 101. For example, when the terminal device 102 periodically executes a program that requires sending and receiving user data, the user data management unit 403 can determine the generation pattern of the communication volume, and when the generation cycle or the time until the next generation timing is shorter than the predetermined time interval, it is determined that the condition for transitioning to the connected state is satisfied. In another example, the amount of user data to be sent can also be predicted based on the history of the amount of user data held by the user data management unit 403, and when it is determined that the predicted amount of user data cannot be sent only through message 3, it is determined that the state should be transitioned to the connected state.

[0081] In one example, the state control unit 404 may determine whether to attempt to transition from the inactive state to the connected state based on the remaining battery level of the terminal device 102 acquired by the battery control unit 406. For example, when the remaining battery level is low, compared to when the remaining battery level is high, even if the amount of data held by the user data management unit 403 is large, the transition to the connected state may not be attempted. Thus, when the remaining battery level is low, the probability of maintaining the inactive state increases, and battery consumption can be suppressed.

[0082] (Structure of Base Station Device)

[0083] Figure 5 1 shows an example of a hardware configuration of the base station device 101 involved in this embodiment. In one example, the base station device 101 includes a processor 501, a ROM 502, a RAM 503, a storage device 504, and a communication circuit 505. These components are the same as the processor 301, ROM 302, RAM 303, storage device 304, and communication circuit 305 of the terminal device 102, and thus description thereof is omitted. It should be noted that the base station device 101 may also include, for example, a communication circuit for communicating with the terminal device 102 and a communication circuit for communicating with a network node.

[0084] Figure 6 : shows an example of a functional configuration of the base station apparatus 101 involved in this embodiment. As its functions, the base station apparatus 101 includes a communication control unit 601, a connection processing unit 602, a state control unit 603, a user data management unit 604, a threshold determination unit 605, and a threshold notification unit 606. It should be noted that the base station apparatus 101 can of course have other functions as a general base station apparatus, but they are omitted here for simplicity of description.

[0085] The communication control unit 601 controls the communication performed between the terminal device 102 and the base station device 101 (for example, wireless communication in accordance with the communication standard of 5G). The communication control unit 601, for example, performs various controls for performing communication with the terminal device 102. In one example, the communication control unit 601 performs various controls for wireless communication in accordance with the 5G standard. The connection processing unit 602 performs message processing of two-step RACH or four-step RACH initiated by the terminal device 102 via the communication control unit 601, thereby establishing a connection with the terminal device 102.

[0086] The state control unit 603 determines whether to instruct a transition to a connected state based on the message 3 of the four-step RACH and the message A of the two-step RACH from the terminal apparatus 102 in the inactive state, as described later.

[0087] The user data management unit 604 temporarily stores the user data received from the terminal device 102 and the user data transmitted to the terminal device 102 .

[0088] The threshold determination unit 605 determines a threshold for determining whether to instruct the terminal device 102 to transition to the connected state. The threshold notification unit 606 generates a signal for notifying the terminal device 102 of the threshold determined by the threshold determination unit 605 (e.g., a broadcast signal (RACH Config), a signal including a message for causing the terminal device 102 to transition to the inactive state (RRCRelease with suspendConfig), the RRCRelease signal being an RRC release signal). The signal generated by the threshold notification unit 606 is notified to the terminal device 102 by the communication control unit 601.

[0089] (Processing flow)

[0090] Next, use Fig. 7A , Figure 7B , Fig. 8A as well as Figure 8B An example of the flow of processing according to this embodiment will be described. Fig. 7A This shows an example in which user data is transmitted and received between the base station apparatus 101 and the terminal apparatus 102 in the inactive state in the four-step RACH, and the terminal apparatus 102 notifies the base station apparatus 101 of a message in which a condition for transitioning to the connected state is not satisfied. Figure 7B This shows an example of a message in which user data is transmitted and received between the base station apparatus 101 and a terminal apparatus in an inactive state in a four-step RACH, and the terminal apparatus 102 notifies the base station apparatus 101 that a condition for transitioning to a connected state is satisfied. Fig. 8A as well as Figure 8B Indicated in Fig. 7A as well as Figure 7B This is an example of a process performed by the terminal device 102 and the base station device 101 in the message process shown.

[0091] exist Fig. 7A as well as Figure 7B In the present invention, first, the terminal device 102 sends a message 1 (message 701) to the base station device 101. Message 701 is the same as the random access preamble of the existing four-step RACH. Then, the base station device 101 sends a message 2 (message 702) as a response to message 701. Message 702 is the same as the random access response of the existing four-step RACH.

[0092] Next, the terminal device 102 that has received the message 702 from the base station device 101 sends a message 3 (messages 703, 713) containing user data to the base station device 101. Here, when the conditions for transitioning to the connected state are met, the terminal device 102 sends a message 713 containing the user data and the RRCResumeRequest. On the other hand, when the conditions for transitioning to the connected state are not met, a message 703 containing the user data but not the RRCResumeRequest is sent. The RRCResumeRequest is a message for requesting a transition to the connected state, and here, it is a message requesting the base station device 101 to send a message 4 containing the RRCResume for instructing the terminal device 102 to transition to the connected state. Thus, the base station device 101 that has received the message 3 can determine whether the terminal device 102 should transition to the connected state by determining whether the RRCResumeRequest is included in the message 3. It should be noted that at least one of the user data and the RRCResumeRequest is transmitted via the PUSCH (Physical Uplink Shared CHannel).

[0093] When the received message 3 is the message 703 that does not include the RRCResumeRequest, the base station apparatus 101 sends the message 4 (message 704) that does not include the RRCResume indicating the transition to the connected state to the terminal apparatus 102. The terminal apparatus 102 that has received the message 704 maintains the inactive state. On the other hand, when the received message 3 is the message 713 that includes the RRCResumeRequest, the base station apparatus 101 sends the message 4 (message 714) that includes the RRCResume indicating the transition to the connected state in the ContentionResolution to the terminal apparatus 102. The terminal apparatus 102 that has received the message 714 sends the RRCResumeComplete (message 715) that transitions from the inactive state to the connected state to the base station apparatus 101, and performs the transmission and reception of the remaining user data. It should be noted that the terminal apparatus 102 may also include the user data in the message 715.

[0094] Next, refer to Fig. 8A An example of processing performed by the terminal apparatus 102 in the four-step RACH according to the present embodiment will be described. Fig. 8A The processing is started by the processor 301 executing a predetermined program when it is determined that there is data to be transmitted to the user data management unit 403 of the terminal device 102.

[0095] First, in S801, the terminal device 102 sends a message 1 of the four-step RACH to the base station device 101. Next, the process proceeds to S802, and waits until a message 2 as a response to the message 1 is received. In the case where it is determined that the message 2 is received ("Yes" in S802), the terminal device 102 proceeds to S803 to determine whether a predetermined condition for transitioning to a connected state is satisfied. In one example, the user data management unit 403 may also determine that a predetermined condition for transitioning to a connected state is satisfied when there is user data exceeding a predetermined amount that has not yet been sent, and determine that the transition to a connected state is not satisfied when the amount of user data that has not yet been sent is less than a predetermined amount. As another example, as described above, the terminal device 102 may determine whether a predetermined condition is satisfied based on the remaining battery power or the business mode.

[0096] When it is determined that the predetermined condition for transitioning to the connected state is satisfied (S803: Yes), the terminal device 102 causes the process to proceed to S804, sends the message 3 including the user data and the RRCResumeRequest to the base station device 101, and causes the process to proceed to S806. On the other hand, when it is determined that the predetermined condition for transitioning to the connected state is not satisfied (S803: No), the terminal device 102 causes the process to proceed to S805, sends the message 3 including the user data but not including the RRCResumeRequest to the base station device 101, and causes the process to proceed to S806.

[0097] In S806 , the terminal device 102 waits until receiving the message 4 which is a response to the message 3 .

[0098] If it is determined that message 4 is received ("Yes" in S806), the terminal device 102 proceeds to S807 to determine whether the received message 4 includes RRCResume. If it is determined that the received message 4 does not include RRCResume (S807: No), the terminal device 102 ends Fig. 8A On the other hand, if it is determined that the received message 4 contains RRCResume ("Yes" in S807), the terminal device 102 advances the processing to S808, changes to the connected state, and sends RRCResumeComplete to the base station device 101. Subsequently, the processing enters S809 to send and receive user data. Fig. 8A The processing is finished.

[0099] Next, refer to Figure 8B An example of processing performed by the base station apparatus 101 in the four-step RACH according to the present embodiment will be described. Figure 8BThe processing is started when the base station apparatus 101 is started, for example, by the processor 501 of the base station apparatus 101 executing a predetermined program.

[0100] First, the base station apparatus 101 waits for message 1 from the terminal apparatus 102 in S851. When it is determined that message 1 is received ("Yes" in S851), the base station apparatus 101 advances the process to S852, and transmits message 2 as a response to message 1. Next, the base station apparatus 101 advances the process to S853, and waits until message 3 is received. When it is determined that message 3 is received ("Yes" in S853), the base station apparatus 101 advances the process to S854, and determines whether RRCResumeRequest is included in the received message 3.

[0101] When it is determined that the received message 3 does not include RRCResumeRequest ("No" in S854), the base station device 101 advances the processing to S855, and the terminal device 102 only needs to send a small amount of user data. It is determined that the terminal device 102 should not transition to the connected state, and a message 4 that does not include RRCResume is sent, and the processing returns to S851. On the other hand, when it is determined that the received message 3 includes RRCResumeRequest ("Yes" in S854), the base station device 101 advances the processing to S856, and determines that the terminal device 102 should transition to the connected state, and sends a message 4 that includes RRCResume. Next, the base station device 101 advances the processing to S857 and waits for RRCResumeComplete. When a message including RRCResumeComplete is received ("Yes" in S857), the base station device 101 advances the processing to S858, communicates with the terminal device 102, and when the communication is completed and the terminal device 102 returns to the inactive state, the processing returns to S851.

[0102] It should be noted that the base station apparatus 101 may include an acknowledgement (ACK) to the user data included in the message 3 received in S854 in the message 4 and transmit it in S855 or S856.

[0103] As described above, during the random access process, the terminal device involved in this embodiment, when the predetermined conditions for transitioning from the inactive state to the connected state are met, sends a message including predetermined information notifying the base station device that the state should be transitioned to the connected state. The predetermined conditions may also be based on the amount of user data to be sent, the remaining battery level, and the traffic pattern. The predetermined information notifying the base station device that the state should be transitioned to the connected state includes RRCResumeRequest. It should be noted that the base station device may also send information related to the predetermined conditions to the terminal device.

[0104] In addition, when the base station device according to the present embodiment receives a first message including user data from a terminal device in an inactive state, the base station device transmits a message including an instruction to transition the terminal device to a connected state when the first message includes predetermined information. The transition instruction includes RRCResume.

[0105] As a result, the base station apparatus can appropriately instruct the terminal apparatus to transition to the connected state, thereby preventing a decrease in frequency utilization efficiency.

[0106] <Second Embodiment>

[0107] In the first embodiment, when the terminal device should transition to a connected state, the terminal device sends a message including an RRCResumeRequest during a random access process. In the second embodiment, an example of a wireless communication system including a terminal device is described, and when the terminal device should transition to a connected state, the terminal device sends a message including information about the amount of user data that the terminal device should send during a random access process. It should be noted that the same figure mark is marked for the same structure or process as the first embodiment, and repeated descriptions are omitted.

[0108] use Fig.9A , Fig. 9B , Fig. 10A as well as Fig. 10B An example of the flow of processing according to this embodiment will be described. Fig.9A This shows an example in which user data is transmitted and received between the base station apparatus and the terminal apparatus in the inactive state in the four-step RACH, and the terminal apparatus 102 notifies the base station apparatus 101 of a message when the condition for transitioning to the connected state is not satisfied. Fig. 9B An example of a message showing the case where user data is sent and received between base station apparatus 101 and terminal apparatus 102 in an inactive state in a four-step RACH, and when a condition is met for terminal apparatus 102 to transition to a connected state, information related to the amount of user data that terminal apparatus 102 should send is notified to base station apparatus 101.

[0109] In message 3, if the terminal device 102 should transition to the connected state, Fig. 9B As shown, the terminal device 102 sends a message 913 including a buffer status report. On the other hand, if the connection state should not be changed, such as Fig.9A As shown, a message 903 is sent that does not include a Buffer Status Report.

[0110] When the received message 3 is the message 913 including the Buffer Status Report, the base station apparatus 101 determines that the terminal apparatus 102 should transition to the connected state, and sends the message 914 including the RRCResume to the terminal apparatus 102. On the other hand, when the received message 3 is the message 903 not including the Buffer Status Report, the base station apparatus 101 determines that the terminal apparatus 102 should not transition to the connected state, and sends the message 904 not including the RRCResume to the terminal apparatus 102.

[0111] Next, refer to Fig. 10A An example of processing performed by the terminal apparatus 102 in the four-step RACH according to the present embodiment will be described. Fig. 10A The processing is started by the processor 301 executing a predetermined program when it is determined that there is data to be transmitted to the user data management unit 403 of the terminal device 102.

[0112] S801 to S803 are the same processes as those in the first embodiment, and therefore the description thereof is omitted. When it is determined that the connection state is to be changed ("Yes" in S803), the terminal device 102 causes the process to proceed to S1001, and the terminal device 102 transmits a message 3 including user data and a Buffer Status Report to the base station device 101, and causes the process to proceed to S806. On the other hand, when it is determined that the connection state is not to be changed ("No" in S803), the terminal device 102 causes the process to proceed to S1002, and transmits a message 3 including user data but not including a Buffer Status Report to the base station device 101, and causes the process to proceed to S806. The subsequent process of the terminal device 102 is the same as that in the first embodiment, and therefore the description thereof is omitted.

[0113] It should be noted that, in one example, the terminal device 102 may transmit information indicating whether the amount of user data held by the user data management unit 403 is greater than a predetermined threshold.

[0114] Next, refer to Fig. 10B An example of processing performed by the base station apparatus 101 in the four-step RACH according to the present embodiment will be described. Fig. 10B The processing is started when the base station apparatus 101 is started, for example, by the processor 501 of the base station apparatus 101 executing a predetermined program.

[0115] The processing in steps S851 to S853 is the same as that in the first embodiment, so the description thereof will be omitted. If it is determined that message 3 is received ("Yes" in S853), the base station apparatus 101 advances the processing to S1051 to determine whether the received message 3 includes a Buffer Status Report.

[0116] When it is determined that the received message 3 does not include the Buffer Status Report ("No" in S1051), the base station device 101 advances the processing to S855, and the terminal device 102 determines that the predetermined condition for transitioning to the connected state is not satisfied, and sends a message 4 that does not include RRCResume, and returns the processing to S851. On the other hand, when it is determined that the received message 3 includes the Buffer Status Report ("Yes" in S1051), the base station device 101 advances the processing to S856, determines that the terminal device 102 satisfies the predetermined condition for transitioning to the connected state, and sends a message 4 including RRCResume. The subsequent processing of the base station device 101 is the same as that of the first embodiment, and therefore the description is omitted.

[0117] As described above, the terminal apparatus according to this embodiment transmits a message including a Buffer Status Report as predetermined information notifying the base station apparatus of the transition to the connected state when a predetermined condition for transitioning from the inactive state to the connected state is satisfied during the random access procedure.

[0118] <Third Embodiment>

[0119] In the third embodiment, when a message received from a terminal device includes information indicating that a transition to a connected state should be made, a base station device is described that further determines whether to instruct the terminal device to transition to a connected state based on the information. It should be noted that the same figure marks are given to the same structures or processes as those in the first embodiment or the second embodiment, and repeated descriptions are omitted.

[0120] use Fig.11A , Fig. 11B as well as Fig.12 An example of the flow of processing according to this embodiment will be described. Fig.11A This example shows a message in which, in four-step RACH, when terminal apparatus 102 satisfies the conditions for transitioning to the connected state, information on the amount of user data that the terminal apparatus should transmit is notified to base station apparatus 101, but base station apparatus 101 does not instruct transition to the connected state. Fig. 11BThis is an example of a message in which, in a four-step RACH, when a condition for terminal apparatus 102 to transition to a connected state is satisfied, information on the amount of user data that terminal apparatus 102 should transmit is notified to base station apparatus 101, and base station apparatus 101 instructs transition to a connected state.

[0121] exist Fig.11A and Fig. 11B In message 3, when the terminal device 102 should transition to the connected state, the terminal device 102 sends a message 1103 including a Buffer Status Report, and when the terminal device 102 should not transition to the connected state, it sends a message 3 not including a Buffer Status Report.

[0122] When the received message 3 (message 1103) includes a Buffer Status Report, the base station device 101 determines whether to make the terminal device 102 transition to the connected state based on the Buffer Status Report. For example, the base station device 101 may also receive the amount of data that the terminal device 102 should send, and when the amount of data to be sent is less than a predetermined amount, send a message 1104 including RRCReject so that the terminal device 102 does not transition to the connected state. On the other hand, when the amount of data to be sent is greater than a predetermined amount, send a message 1114 including RRCResume to instruct the terminal device 102 to transition to the connected state.

[0123] It should be noted that when the received message 3 does not include a Buffer Status Report, similar to the second embodiment, the base station device 101 determines that the terminal device 102 should not transition to the connected state and sends a message 4 that does not include RRCResume to the terminal device 102.

[0124] Next, refer to Fig.12 An example of processing performed by the base station apparatus 101 in the four-step RACH according to the present embodiment will be described. Fig.12 The processing is started by the processor 501 of the base station apparatus 101 executing a predetermined program when the base station apparatus 101 is activated, etc. In addition, the processing performed by the terminal apparatus 102 in the four-step RACH according to the present embodiment is the same as that in the second embodiment, and therefore the description thereof is omitted.

[0125] The processing in steps S851 to S853 is the same as that in the first embodiment, so the description thereof will be omitted. If it is determined that message 3 is received ("Yes" in S853), the base station apparatus 101 advances the processing to S1251 to determine whether the received message 3 includes a Buffer Status Report.

[0126] When it is determined that the received message 3 does not include a Buffer Status Report ("No" in S1251), the base station apparatus 101 advances the processing to S1253, and the terminal apparatus 102 only needs to send a small amount of user data, and it is determined that the transition to the connected state should not be made, and a message 4 including RRCReject is sent and the processing is terminated. On the other hand, when it is determined that the received message 3 includes a Buffer Status Report ("Yes" in S1251), the base station apparatus 101 advances the processing to S1252, and determines whether the amount of user data to be sent by the terminal apparatus 102 included in the Buffer Status Report received from the terminal apparatus 102 is greater than a threshold. In one example, the threshold is a threshold determined by the threshold determination unit 605. When the amount of user data to be sent included in the Buffer Status Report is greater than the threshold ("Yes" in S1252), the processing advances to S1254, and the base station apparatus 101 sends a message 4 including RRCResume to the terminal apparatus 102, indicating the transition to the connected state. On the other hand, when the amount of user data to be sent is below the threshold ("No" in S1252), the base station apparatus 101 causes the process to enter S1253, and sends a message 4 including RRCReject to the terminal apparatus 102, rejecting the transition to the connected state. In one example, when the base station apparatus 101 determines that the terminal apparatus 102 does not meet the predetermined conditions for transitioning to the connected state, it may also send a message including RRCRelease with suspend Config. The subsequent processing of the base station apparatus 101 is the same as that of the first embodiment, so the description is omitted.

[0127] As described above, when the base station device according to the present embodiment receives the first message including user data from the terminal device in the inactive state, the terminal device instructs the terminal device to transition to the connected state based on whether the buffer status report indicating the amount of user data exceeding the predetermined amount included in the first message is included. Thus, the transition to the connected state can be appropriately instructed to the terminal device, and the reduction of the frequency utilization efficiency can be prevented.

[0128] <Fourth Embodiment>

[0129] In the fourth embodiment, an example of processing of a wireless communication system that determines to send a message to instruct a terminal device to transition to a connected state when a message received from a terminal device contains information indicating that a transition to a connected state is to be made in a two-step random access process is described. It should be noted that the same reference numerals are given to the same structure or process as any one of the first to third embodiments, and repeated descriptions are omitted.

[0130] Will refer to Fig.13A , Fig. 13B , Fig.14A and Fig. 14B An example of the flow of processing involved according to the present embodiment is described. Fig.13A This shows an example in which user data is transmitted and received between base station apparatus 101 and terminal apparatus 102 in an inactive state in a two-step RACH, and terminal apparatus 102 notifies base station apparatus 101 of a message indicating that a condition for transitioning to a connected state is not satisfied. Fig. 13B This shows an example in which user data is transmitted and received between base station apparatus 101 and terminal apparatus 102 in an inactive state in a two-step RACH, and terminal apparatus 102 notifies base station apparatus 101 of a message when a condition for transitioning to a connected state is satisfied.

[0131] exist Fig.13A In the example, first, the terminal device 102 sends a message A to the base station device 101. The message A includes a random access preamble (RA preamble) and user data. The user data is sent via the PUSCH. If the terminal device 102 does not meet the predetermined conditions for transitioning to the connected state, such as Fig.13A As shown, the terminal device 102 sends a message 1301 which is a message A that does not include RRCResumeRequest. On the other hand, when the terminal device 102 satisfies a predetermined condition to transition to the connected state, such as Fig. 13B As shown, the terminal device 102 sends message 1311 which is message A including RRCResumeRequest.

[0132] like Fig.13A As shown in FIG. 1 , when the base station device 101 receives the message 1301 that does not include the RRCResumeRequest, it sends a message B (message 1302) including a random access response (RA response), a Content Resolution, and user data in response. In one example, the user data included in the message 1302 includes an ACK for the user data included in the message 1301. On the other hand, Fig. 13BAs shown, when the base station device 101 receives the message 1311 including the RRCResumeRequest, in response, in addition to the RA response, Contentin Resolution and user data, it also sends a message 1312 as a message B including the RRCResume. When the terminal device 102 receives the message 1302, it determines that there is no instruction to transition to the connected state, maintains the inactive state and ends the two-step RACH. On the other hand, the terminal device 102 that receives the message 1312 sends a message 1313 including the RRCResumeComplete, transitions to the connected state, and transmits and receives user data.

[0133] Next, refer to Fig.14A An example of processing performed by the terminal apparatus 102 in the two-step RACH according to the present embodiment will be described. Fig.14A The processing is started by the processor 301 executing a predetermined program when it is determined that there is data to be transmitted to the user data management unit 403 of the terminal device 102.

[0134] First, in step S1401, the terminal device 102 determines whether to transition to the connected state. As described above, when the terminal device 102 determines that the user data management unit 403 has a predetermined amount of user data or more, it may determine that the terminal device 102 should transition to the connected state.

[0135] If it is determined that the connection state should be changed ("Yes" in S1401), the terminal device 102 advances the process to S1402 and sends a message A including RRCResumeRequest. On the other hand, if it is determined that the connection state should not be changed ("No" in S1401), the terminal device 102 advances the process to S1403 and sends a message A not including RRCResumeRequest. This message A may include user data regardless of whether the packet does not include RRCResumeRequest.

[0136] Next, the terminal device 102 causes the process to enter S1404, and the terminal device 102 waits until the message B is received from the base station device 101. When it is determined that the message B is received ("Yes" in step S1404), the terminal device 102 causes the process to enter step S1405, and determines whether the received message B includes RRCResume. When the received message B does not include RRCResume ("No" in S1405), the terminal device 102 ends. Fig.14AOn the other hand, if the received message B includes RRCResume ("Yes" in S1045), the terminal device 102 advances the process to S1406. The processes in steps S1406 and S1407 are the same as those in step S1408. Fig. 8A The processing in steps S808 and S809 is the same, so their description is omitted.

[0137] Next, refer to Fig. 14B An example of processing performed by the base station apparatus 101 in the two-step RACH according to the present embodiment will be described. Fig. 14B The processing is started when the base station apparatus 101 is started, for example, by the processor 501 of the base station apparatus 101 executing a predetermined program.

[0138] First, in S1451, the base station apparatus 101 waits for message A of the two-step RACH. When it is determined that message A is received ("Yes" in S1451), the terminal apparatus 102 causes the processing to proceed to S1452 to determine whether the received message A includes RRCResumeRequest. If it is determined that message A includes RRCResumeRequest, the base station apparatus 101 causes the processing to proceed to S1454 to send message B including RRCResume to the terminal apparatus 102. On the other hand, if it is determined that message A does not include RRCResumeRequest, the base station apparatus 101 causes the processing to proceed to S1453 to send message B that does not include RRCResume. It should be noted that message B may also include user data, and in one example, may also include an ACK for the user data included in the received message A. The subsequent processing in steps S1455 and S1456 is the same as Figure 8B The processing in steps S857 and S858 is the same, so their description is omitted.

[0139] As described above, when the terminal device according to the present embodiment transmits and receives user data with the base station device in the two-step random access process, a message including information related to the amount of user data to be transmitted by the terminal device is transmitted as information indicating that the state should be changed to the connected state. Thus, the base station device can determine whether to instruct the terminal device to change to the connected state, can perform appropriate message processing, and can prevent a decrease in frequency utilization efficiency.

[0140] <Other Implementation Methods>

[0141] The present invention is not limited to the above-described embodiments, and various modifications and changes can be made within the scope of the gist of the invention.

[0142] For example, in the two-step RACH message processing described in the fourth embodiment, when the terminal apparatus determines that it is necessary to transition to the connected state, the message A including the Buffer Status Report may be transmitted as described in the third embodiment.

[0143] The present invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the present invention. Therefore, claims are added to disclose the scope of the present invention.

[0144] This application claims priority based on Japanese patent application No. 2019-176948 filed on September 27, 2019, the entire contents of which are incorporated herein by reference.

Claims

1. A terminal device, the terminal device having a sending unit, the sending unit sending a first message containing user data to a base station device during a random access process of a mobile communication network, wherein: The terminal device includes a control unit, which controls the sending unit so that: When a predetermined condition for transitioning from the inactive state to the connected state is satisfied, sending the first message including predetermined information for notifying the base station device that the terminal device should transition to the connected state, If the predetermined condition is not met, sending the first message without the predetermined information, The predetermined information includes an RRC resumption request for requesting an instruction to transition to the connected state, and the predetermined condition is based on a traffic pattern of user data to be transmitted to the base station device.

2. The terminal device according to claim 1, wherein: The terminal device further includes a first receiving unit configured to receive a second message from the base station device as a response to the first message. The control unit controls the terminal device so that: In a case where the second message includes an instruction to transition to the connected state, transition to the connected state, When the second message does not include the indication, the inactive state is maintained.

3. The terminal device according to claim 1 or 2, wherein: The predetermined information includes a buffer status report indicating the amount of user data to be transmitted to the base station apparatus.

4. The terminal device according to claim 1, wherein: Among the predetermined conditions, a traffic pattern of user data to be transmitted to the base station apparatus is shorter than a predetermined time interval.

5. The terminal device according to claim 1, wherein: The terminal device further includes a second receiving unit that receives information corresponding to the predetermined condition from the base station device.

6. The terminal device according to claim 1, wherein: The random access procedure is a four-step random access procedure. The first message is a message sent after a random access response.

7. The terminal device according to claim 1, wherein: The random access procedure is a two-step random access procedure. The first message also includes a random access preamble.

8. A base station device, which is a base station device of a mobile communication network, wherein: The base station device comprises: a receiving unit, wherein during a random access process, the receiving unit receives a first message including user data from a terminal device in an inactive state; a first sending unit, which sends a second message as a response to the first message; as well as A control unit controls the first sending unit so that: When the first message includes predetermined information, sending the second message including an instruction to make the terminal device transition to a connected state, In the case where the first message does not include the predetermined information, sending the second message that does not include the indication, The predetermined information includes an RRC recovery request for requesting an indication of transition to the connected state, and the predetermined information is included in the first message when a predetermined condition based on a traffic pattern of user data that the terminal device should send to the base station device is satisfied.

9. The base station device according to claim 8, wherein: The predetermined information includes a buffer status report indicating an amount of user data equal to or larger than a predetermined amount to be transmitted to the base station apparatus.

10. The base station device according to claim 9, wherein: The base station device further includes a second transmission unit configured to transmit, to the terminal device, a predetermined condition for transmitting the first message including the predetermined information.

11. The base station device according to claim 10, wherein: The second sending unit sends information corresponding to the predetermined amount to the terminal device through a broadcast signal or an RRC release signal.

12. A control method, the control method being executed by a terminal device of a mobile communication network, wherein: The control method comprises a sending step, in which a first message including user data is sent to a base station device during a random access process; In the sending step, When a predetermined condition for transitioning from the inactive state to the connected state is satisfied, sending the first message including predetermined information for notifying the base station device that the terminal device should transition to the connected state, If the predetermined condition is not met, sending the first message without the predetermined information, The predetermined information includes an RRC recovery request indicating a request for transition to the connected state, The predetermined condition is based on a traffic pattern of user data to be transmitted to the base station apparatus.

13. A computer-readable recording medium storing a program for causing a computer of a terminal device of a mobile communication network to send a first message including user data to a base station device during a random access procedure, wherein: The program is used to control the terminal device so that: When a predetermined condition for transitioning from the inactive state to the connected state is satisfied, sending the first message including predetermined information for notifying the base station device that the terminal device should transition to the connected state, If the predetermined condition is not met, sending the first message without the predetermined information, The predetermined information includes an RRC resumption request for requesting an instruction to transition to the connected state, and the predetermined condition is based on a traffic pattern of user data to be transmitted to the base station device.

14. A control method, the control method being executed by a base station device of a mobile communication network, wherein: The control method comprises the following steps: A receiving step, in which a first message including user data is received from a terminal device in an inactive state during a random access procedure; as well as a sending step, in which a second message is sent as a response to the first message; In the sending step, When the first message includes predetermined information, the second message including an instruction to change the terminal device to a connected state is sent to the terminal device, When the first message does not include the predetermined information, sending the second message that does not include the instruction to the terminal device, The predetermined information includes an RRC recovery request indicating a request for transition to the connected state, When a predetermined condition based on a traffic pattern of user data that the terminal device should transmit to the base station device is satisfied, the predetermined information is included in the first message.

15. A computer-readable recording medium storing a program for controlling a terminal device so that a computer included in a base station device of a mobile communication network executes the following steps: In a random access procedure, receiving a first message including user data from the terminal device in an inactive state, sending a second message as a response to the first message, in, When the first message includes predetermined information, sending the second message including an instruction to make the terminal device transition to a connected state, In the case where the first message does not include the predetermined information, sending the second message that does not include the indication, The predetermined information includes an RRC recovery request indicating a request for transition to the connected state, When a predetermined condition based on a traffic pattern of user data that the terminal device should transmit to the base station device is satisfied, the predetermined information is included in the first message.

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